LU-10070 lod: SEL: interoperability support

[fs/lustre-release.git] / lustre / lod / lod_object.c

/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License version 2 for more details.  A copy is
 * included in the COPYING file that accompanied this code.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * GPL HEADER END
 */
/*
 * Copyright  2009 Sun Microsystems, Inc. All rights reserved
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, 2017, Intel Corporation.
 */
/*
 * lustre/lod/lod_object.c
 *
 * This file contains implementations of methods for the OSD API
 * for the Logical Object Device (LOD) layer, which provides a virtual
 * local OSD object interface to the MDD layer, and abstracts the
 * addressing of local (OSD) and remote (OSP) objects. The API is
 * described in the file lustre/include/dt_object.h and in
 * Documentation/osd-api.txt.
 *
 * Author: Alex Zhuravlev <alexey.zhuravlev@intel.com>
 */

#define DEBUG_SUBSYSTEM S_MDS

#include <linux/random.h>

#include <obd.h>
#include <obd_class.h>
#include <obd_support.h>

#include <lustre_fid.h>
#include <lustre_linkea.h>
#include <lustre_lmv.h>
#include <uapi/linux/lustre/lustre_param.h>
#include <lustre_swab.h>
#include <uapi/linux/lustre/lustre_ver.h>
#include <lprocfs_status.h>
#include <md_object.h>

#include "lod_internal.h"

static const char dot[] = ".";
static const char dotdot[] = "..";

/**
 * Implementation of dt_index_operations::dio_lookup
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_index_operations::dio_lookup() in the API description for details.
 */
static int lod_lookup(const struct lu_env *env, struct dt_object *dt,
                      struct dt_rec *rec, const struct dt_key *key)
{
        struct dt_object *next = dt_object_child(dt);
        return next->do_index_ops->dio_lookup(env, next, rec, key);
}

/**
 * Implementation of dt_index_operations::dio_declare_insert.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_index_operations::dio_declare_insert() in the API description
 * for details.
 */
static int lod_declare_insert(const struct lu_env *env, struct dt_object *dt,
                              const struct dt_rec *rec,
                              const struct dt_key *key, struct thandle *th)
{
        return lod_sub_declare_insert(env, dt_object_child(dt), rec, key, th);
}

/**
 * Implementation of dt_index_operations::dio_insert.
 *
 * Used with regular (non-striped) objects
 *
 * \see dt_index_operations::dio_insert() in the API description for details.
 */
static int lod_insert(const struct lu_env *env, struct dt_object *dt,
                      const struct dt_rec *rec, const struct dt_key *key,
                      struct thandle *th)
{
        return lod_sub_insert(env, dt_object_child(dt), rec, key, th);
}

/**
 * Implementation of dt_index_operations::dio_declare_delete.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_index_operations::dio_declare_delete() in the API description
 * for details.
 */
static int lod_declare_delete(const struct lu_env *env, struct dt_object *dt,
                              const struct dt_key *key, struct thandle *th)
{
        return lod_sub_declare_delete(env, dt_object_child(dt), key, th);
}

/**
 * Implementation of dt_index_operations::dio_delete.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_index_operations::dio_delete() in the API description for details.
 */
static int lod_delete(const struct lu_env *env, struct dt_object *dt,
                      const struct dt_key *key, struct thandle *th)
{
        return lod_sub_delete(env, dt_object_child(dt), key, th);
}

/**
 * Implementation of dt_it_ops::init.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::init() in the API description for details.
 */
static struct dt_it *lod_it_init(const struct lu_env *env,
                                 struct dt_object *dt, __u32 attr)
{
        struct dt_object        *next = dt_object_child(dt);
        struct lod_it           *it = &lod_env_info(env)->lti_it;
        struct dt_it            *it_next;

        it_next = next->do_index_ops->dio_it.init(env, next, attr);
        if (IS_ERR(it_next))
                return it_next;

        /* currently we do not use more than one iterator per thread
         * so we store it in thread info. if at some point we need
         * more active iterators in a single thread, we can allocate
         * additional ones */
        LASSERT(it->lit_obj == NULL);

        it->lit_it = it_next;
        it->lit_obj = next;

        return (struct dt_it *)it;
}

#define LOD_CHECK_IT(env, it)                                   \
do {                                                            \
        LASSERT((it)->lit_obj != NULL);                         \
        LASSERT((it)->lit_it != NULL);                          \
} while (0)

/**
 * Implementation of dt_index_operations::dio_it.fini.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_index_operations::dio_it.fini() in the API description for details.
 */
static void lod_it_fini(const struct lu_env *env, struct dt_it *di)
{
        struct lod_it *it = (struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        it->lit_obj->do_index_ops->dio_it.fini(env, it->lit_it);

        /* the iterator not in use any more */
        it->lit_obj = NULL;
        it->lit_it = NULL;
}

/**
 * Implementation of dt_it_ops::get.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::get() in the API description for details.
 */
static int lod_it_get(const struct lu_env *env, struct dt_it *di,
                      const struct dt_key *key)
{
        const struct lod_it *it = (const struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.get(env, it->lit_it, key);
}

/**
 * Implementation of dt_it_ops::put.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::put() in the API description for details.
 */
static void lod_it_put(const struct lu_env *env, struct dt_it *di)
{
        struct lod_it *it = (struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.put(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::next.
 *
 * Used with regular (non-striped) objects
 *
 * \see dt_it_ops::next() in the API description for details.
 */
static int lod_it_next(const struct lu_env *env, struct dt_it *di)
{
        struct lod_it *it = (struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.next(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::key.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::key() in the API description for details.
 */
static struct dt_key *lod_it_key(const struct lu_env *env,
                                 const struct dt_it *di)
{
        const struct lod_it *it = (const struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.key(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::key_size.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::key_size() in the API description for details.
 */
static int lod_it_key_size(const struct lu_env *env, const struct dt_it *di)
{
        struct lod_it *it = (struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.key_size(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::rec.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::rec() in the API description for details.
 */
static int lod_it_rec(const struct lu_env *env, const struct dt_it *di,
                      struct dt_rec *rec, __u32 attr)
{
        const struct lod_it *it = (const struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.rec(env, it->lit_it, rec,
                                                     attr);
}

/**
 * Implementation of dt_it_ops::rec_size.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::rec_size() in the API description for details.
 */
static int lod_it_rec_size(const struct lu_env *env, const struct dt_it *di,
                           __u32 attr)
{
        const struct lod_it *it = (const struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.rec_size(env, it->lit_it,
                                                          attr);
}

/**
 * Implementation of dt_it_ops::store.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::store() in the API description for details.
 */
static __u64 lod_it_store(const struct lu_env *env, const struct dt_it *di)
{
        const struct lod_it *it = (const struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.store(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::load.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::load() in the API description for details.
 */
static int lod_it_load(const struct lu_env *env, const struct dt_it *di,
                       __u64 hash)
{
        const struct lod_it *it = (const struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.load(env, it->lit_it, hash);
}

/**
 * Implementation of dt_it_ops::key_rec.
 *
 * Used with regular (non-striped) objects.
 *
 * \see dt_it_ops::rec() in the API description for details.
 */
static int lod_it_key_rec(const struct lu_env *env, const struct dt_it *di,
                          void *key_rec)
{
        const struct lod_it *it = (const struct lod_it *)di;

        LOD_CHECK_IT(env, it);
        return it->lit_obj->do_index_ops->dio_it.key_rec(env, it->lit_it,
                                                         key_rec);
}

static struct dt_index_operations lod_index_ops = {
        .dio_lookup             = lod_lookup,
        .dio_declare_insert     = lod_declare_insert,
        .dio_insert             = lod_insert,
        .dio_declare_delete     = lod_declare_delete,
        .dio_delete             = lod_delete,
        .dio_it = {
                .init           = lod_it_init,
                .fini           = lod_it_fini,
                .get            = lod_it_get,
                .put            = lod_it_put,
                .next           = lod_it_next,
                .key            = lod_it_key,
                .key_size       = lod_it_key_size,
                .rec            = lod_it_rec,
                .rec_size       = lod_it_rec_size,
                .store          = lod_it_store,
                .load           = lod_it_load,
                .key_rec        = lod_it_key_rec,
        }
};

/**
 * Implementation of dt_it_ops::init.
 *
 * Used with striped objects. Internally just initializes the iterator
 * on the first stripe.
 *
 * \see dt_it_ops::init() in the API description for details.
 */
static struct dt_it *lod_striped_it_init(const struct lu_env *env,
                                         struct dt_object *dt, __u32 attr)
{
        struct lod_object *lo = lod_dt_obj(dt);
        struct dt_object *next;
        struct lod_it *it = &lod_env_info(env)->lti_it;
        struct dt_it *it_next;
        __u16 index = 0;

        LASSERT(lo->ldo_dir_stripe_count > 0);

        do {
                next = lo->ldo_stripe[index];
                if (next && dt_object_exists(next))
                        break;
        } while (++index < lo->ldo_dir_stripe_count);

        /* no valid stripe */
        if (!next || !dt_object_exists(next))
                return ERR_PTR(-ENODEV);

        LASSERT(next->do_index_ops != NULL);

        it_next = next->do_index_ops->dio_it.init(env, next, attr);
        if (IS_ERR(it_next))
                return it_next;

        /* currently we do not use more than one iterator per thread
         * so we store it in thread info. if at some point we need
         * more active iterators in a single thread, we can allocate
         * additional ones */
        LASSERT(it->lit_obj == NULL);

        it->lit_stripe_index = index;
        it->lit_attr = attr;
        it->lit_it = it_next;
        it->lit_obj = dt;

        return (struct dt_it *)it;
}

#define LOD_CHECK_STRIPED_IT(env, it, lo)                               \
do {                                                                    \
        LASSERT((it)->lit_obj != NULL);                                 \
        LASSERT((it)->lit_it != NULL);                                  \
        LASSERT((lo)->ldo_dir_stripe_count > 0);                        \
        LASSERT((it)->lit_stripe_index < (lo)->ldo_dir_stripe_count);   \
} while (0)

/**
 * Implementation of dt_it_ops::fini.
 *
 * Used with striped objects.
 *
 * \see dt_it_ops::fini() in the API description for details.
 */
static void lod_striped_it_fini(const struct lu_env *env, struct dt_it *di)
{
        struct lod_it           *it = (struct lod_it *)di;
        struct lod_object       *lo = lod_dt_obj(it->lit_obj);
        struct dt_object        *next;

        /* If lit_it == NULL, then it means the sub_it has been finished,
         * which only happens in failure cases, see lod_striped_it_next() */
        if (it->lit_it != NULL) {
                LOD_CHECK_STRIPED_IT(env, it, lo);

                next = lo->ldo_stripe[it->lit_stripe_index];
                if (next) {
                        LASSERT(next->do_index_ops != NULL);
                        next->do_index_ops->dio_it.fini(env, it->lit_it);
                }
        }

        /* the iterator not in use any more */
        it->lit_obj = NULL;
        it->lit_it = NULL;
        it->lit_stripe_index = 0;
}

/**
 * Implementation of dt_it_ops::get.
 *
 * Right now it's not used widely, only to reset the iterator to the
 * initial position. It should be possible to implement a full version
 * which chooses a correct stripe to be able to position with any key.
 *
 * \see dt_it_ops::get() in the API description for details.
 */
static int lod_striped_it_get(const struct lu_env *env, struct dt_it *di,
                              const struct dt_key *key)
{
        const struct lod_it *it = (const struct lod_it *)di;
        struct lod_object *lo = lod_dt_obj(it->lit_obj);
        struct dt_object *next;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(dt_object_exists(next));
        LASSERT(next->do_index_ops != NULL);

        return next->do_index_ops->dio_it.get(env, it->lit_it, key);
}

/**
 * Implementation of dt_it_ops::put.
 *
 * Used with striped objects.
 *
 * \see dt_it_ops::put() in the API description for details.
 */
static void lod_striped_it_put(const struct lu_env *env, struct dt_it *di)
{
        struct lod_it *it = (struct lod_it *)di;
        struct lod_object *lo = lod_dt_obj(it->lit_obj);
        struct dt_object *next;

        /*
         * If lit_it == NULL, then it means the sub_it has been finished,
         * which only happens in failure cases, see lod_striped_it_next()
         */
        if (!it->lit_it)
                return;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);

        return next->do_index_ops->dio_it.put(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::next.
 *
 * Used with striped objects. When the end of the current stripe is
 * reached, the method takes the next stripe's iterator.
 *
 * \see dt_it_ops::next() in the API description for details.
 */
static int lod_striped_it_next(const struct lu_env *env, struct dt_it *di)
{
        struct lod_it *it = (struct lod_it *)di;
        struct lod_object *lo = lod_dt_obj(it->lit_obj);
        struct dt_object *next;
        struct dt_it *it_next;
        __u32 index;
        int rc;

        ENTRY;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(dt_object_exists(next));
        LASSERT(next->do_index_ops != NULL);
again:
        rc = next->do_index_ops->dio_it.next(env, it->lit_it);
        if (rc < 0)
                RETURN(rc);

        if (rc == 0 && it->lit_stripe_index == 0)
                RETURN(rc);

        if (rc == 0 && it->lit_stripe_index > 0) {
                struct lu_dirent *ent;

                ent = (struct lu_dirent *)lod_env_info(env)->lti_key;

                rc = next->do_index_ops->dio_it.rec(env, it->lit_it,
                                                    (struct dt_rec *)ent,
                                                    it->lit_attr);
                if (rc != 0)
                        RETURN(rc);

                /* skip . and .. for slave stripe */
                if ((strncmp(ent->lde_name, ".",
                             le16_to_cpu(ent->lde_namelen)) == 0 &&
                     le16_to_cpu(ent->lde_namelen) == 1) ||
                    (strncmp(ent->lde_name, "..",
                             le16_to_cpu(ent->lde_namelen)) == 0 &&
                     le16_to_cpu(ent->lde_namelen) == 2))
                        goto again;

                RETURN(rc);
        }

        next->do_index_ops->dio_it.put(env, it->lit_it);
        next->do_index_ops->dio_it.fini(env, it->lit_it);
        it->lit_it = NULL;

        /* go to next stripe */
        index = it->lit_stripe_index;
        while (++index < lo->ldo_dir_stripe_count) {
                next = lo->ldo_stripe[index];
                if (!next)
                        continue;

                if (!dt_object_exists(next))
                        continue;

                rc = next->do_ops->do_index_try(env, next,
                                                &dt_directory_features);
                if (rc != 0)
                        RETURN(rc);

                LASSERT(next->do_index_ops != NULL);

                it_next = next->do_index_ops->dio_it.init(env, next,
                                                          it->lit_attr);
                if (IS_ERR(it_next))
                        RETURN(PTR_ERR(it_next));

                rc = next->do_index_ops->dio_it.get(env, it_next,
                                                    (const struct dt_key *)"");
                if (rc <= 0)
                        RETURN(rc == 0 ? -EIO : rc);

                it->lit_it = it_next;
                it->lit_stripe_index = index;
                goto again;

        }

        RETURN(1);
}

/**
 * Implementation of dt_it_ops::key.
 *
 * Used with striped objects.
 *
 * \see dt_it_ops::key() in the API description for details.
 */
static struct dt_key *lod_striped_it_key(const struct lu_env *env,
                                         const struct dt_it *di)
{
        const struct lod_it     *it = (const struct lod_it *)di;
        struct lod_object       *lo = lod_dt_obj(it->lit_obj);
        struct dt_object        *next;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);

        return next->do_index_ops->dio_it.key(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::key_size.
 *
 * Used with striped objects.
 *
 * \see dt_it_ops::size() in the API description for details.
 */
static int lod_striped_it_key_size(const struct lu_env *env,
                                   const struct dt_it *di)
{
        struct lod_it           *it = (struct lod_it *)di;
        struct lod_object       *lo = lod_dt_obj(it->lit_obj);
        struct dt_object        *next;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);

        return next->do_index_ops->dio_it.key_size(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::rec.
 *
 * Used with striped objects.
 *
 * \see dt_it_ops::rec() in the API description for details.
 */
static int lod_striped_it_rec(const struct lu_env *env, const struct dt_it *di,
                              struct dt_rec *rec, __u32 attr)
{
        const struct lod_it     *it = (const struct lod_it *)di;
        struct lod_object       *lo = lod_dt_obj(it->lit_obj);
        struct dt_object        *next;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);

        return next->do_index_ops->dio_it.rec(env, it->lit_it, rec, attr);
}

/**
 * Implementation of dt_it_ops::rec_size.
 *
 * Used with striped objects.
 *
 * \see dt_it_ops::rec_size() in the API description for details.
 */
static int lod_striped_it_rec_size(const struct lu_env *env,
                                   const struct dt_it *di, __u32 attr)
{
        struct lod_it           *it = (struct lod_it *)di;
        struct lod_object       *lo = lod_dt_obj(it->lit_obj);
        struct dt_object        *next;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);

        return next->do_index_ops->dio_it.rec_size(env, it->lit_it, attr);
}

/**
 * Implementation of dt_it_ops::store.
 *
 * Used with striped objects.
 *
 * \see dt_it_ops::store() in the API description for details.
 */
static __u64 lod_striped_it_store(const struct lu_env *env,
                                  const struct dt_it *di)
{
        const struct lod_it     *it = (const struct lod_it *)di;
        struct lod_object       *lo = lod_dt_obj(it->lit_obj);
        struct dt_object        *next;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);

        return next->do_index_ops->dio_it.store(env, it->lit_it);
}

/**
 * Implementation of dt_it_ops::load.
 *
 * Used with striped objects.
 *
 * \see dt_it_ops::load() in the API description for details.
 */
static int lod_striped_it_load(const struct lu_env *env,
                               const struct dt_it *di, __u64 hash)
{
        const struct lod_it     *it = (const struct lod_it *)di;
        struct lod_object       *lo = lod_dt_obj(it->lit_obj);
        struct dt_object        *next;

        LOD_CHECK_STRIPED_IT(env, it, lo);

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        LASSERT(next->do_index_ops != NULL);

        return next->do_index_ops->dio_it.load(env, it->lit_it, hash);
}

static struct dt_index_operations lod_striped_index_ops = {
        .dio_lookup             = lod_lookup,
        .dio_declare_insert     = lod_declare_insert,
        .dio_insert             = lod_insert,
        .dio_declare_delete     = lod_declare_delete,
        .dio_delete             = lod_delete,
        .dio_it = {
                .init           = lod_striped_it_init,
                .fini           = lod_striped_it_fini,
                .get            = lod_striped_it_get,
                .put            = lod_striped_it_put,
                .next           = lod_striped_it_next,
                .key            = lod_striped_it_key,
                .key_size       = lod_striped_it_key_size,
                .rec            = lod_striped_it_rec,
                .rec_size       = lod_striped_it_rec_size,
                .store          = lod_striped_it_store,
                .load           = lod_striped_it_load,
        }
};

/**
 * Append the FID for each shard of the striped directory after the
 * given LMV EA header.
 *
 * To simplify striped directory and the consistency verification,
 * we only store the LMV EA header on disk, for both master object
 * and slave objects. When someone wants to know the whole LMV EA,
 * such as client readdir(), we can build the entrie LMV EA on the
 * MDT side (in RAM) via iterating the sub-directory entries that
 * are contained in the master object of the stripe directory.
 *
 * For the master object of the striped directroy, the valid name
 * for each shard is composed of the ${shard_FID}:${shard_idx}.
 *
 * There may be holes in the LMV EA if some shards' name entries
 * are corrupted or lost.
 *
 * \param[in] env       pointer to the thread context
 * \param[in] lo        pointer to the master object of the striped directory
 * \param[in] buf       pointer to the lu_buf which will hold the LMV EA
 * \param[in] resize    whether re-allocate the buffer if it is not big enough
 *
 * \retval              positive size of the LMV EA
 * \retval              0 for nothing to be loaded
 * \retval              negative error number on failure
 */
int lod_load_lmv_shards(const struct lu_env *env, struct lod_object *lo,
                        struct lu_buf *buf, bool resize)
{
        struct lu_dirent        *ent    =
                        (struct lu_dirent *)lod_env_info(env)->lti_key;
        struct lod_device       *lod    = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        struct dt_object        *obj    = dt_object_child(&lo->ldo_obj);
        struct lmv_mds_md_v1    *lmv1   = buf->lb_buf;
        struct dt_it            *it;
        const struct dt_it_ops  *iops;
        __u32                    stripes;
        __u32                    magic  = le32_to_cpu(lmv1->lmv_magic);
        size_t                   lmv1_size;
        int                      rc;
        ENTRY;

        if (magic != LMV_MAGIC_V1)
                RETURN(0);

        stripes = le32_to_cpu(lmv1->lmv_stripe_count);
        if (stripes < 1)
                RETURN(0);

        rc = lmv_mds_md_size(stripes, magic);
        if (rc < 0)
                RETURN(rc);
        lmv1_size = rc;
        if (buf->lb_len < lmv1_size) {
                struct lu_buf tbuf;

                if (!resize)
                        RETURN(-ERANGE);

                tbuf = *buf;
                buf->lb_buf = NULL;
                buf->lb_len = 0;
                lu_buf_alloc(buf, lmv1_size);
                lmv1 = buf->lb_buf;
                if (lmv1 == NULL)
                        RETURN(-ENOMEM);

                memcpy(buf->lb_buf, tbuf.lb_buf, tbuf.lb_len);
        }

        if (unlikely(!dt_try_as_dir(env, obj)))
                RETURN(-ENOTDIR);

        memset(&lmv1->lmv_stripe_fids[0], 0, stripes * sizeof(struct lu_fid));
        iops = &obj->do_index_ops->dio_it;
        it = iops->init(env, obj, LUDA_64BITHASH);
        if (IS_ERR(it))
                RETURN(PTR_ERR(it));

        rc = iops->load(env, it, 0);
        if (rc == 0)
                rc = iops->next(env, it);
        else if (rc > 0)
                rc = 0;

        while (rc == 0) {
                char             name[FID_LEN + 2] = "";
                struct lu_fid    fid;
                __u32            index;
                int              len;

                rc = iops->rec(env, it, (struct dt_rec *)ent, LUDA_64BITHASH);
                if (rc != 0)
                        break;

                rc = -EIO;

                fid_le_to_cpu(&fid, &ent->lde_fid);
                ent->lde_namelen = le16_to_cpu(ent->lde_namelen);
                if (ent->lde_name[0] == '.') {
                        if (ent->lde_namelen == 1)
                                goto next;

                        if (ent->lde_namelen == 2 && ent->lde_name[1] == '.')
                                goto next;
                }

                len = snprintf(name, sizeof(name),
                               DFID":", PFID(&ent->lde_fid));
                /* The ent->lde_name is composed of ${FID}:${index} */
                if (ent->lde_namelen < len + 1 ||
                    memcmp(ent->lde_name, name, len) != 0) {
                        CDEBUG(lod->lod_lmv_failout ? D_ERROR : D_INFO,
                               "%s: invalid shard name %.*s with the FID "DFID
                               " for the striped directory "DFID", %s\n",
                               lod2obd(lod)->obd_name, ent->lde_namelen,
                               ent->lde_name, PFID(&fid),
                               PFID(lu_object_fid(&obj->do_lu)),
                               lod->lod_lmv_failout ? "failout" : "skip");

                        if (lod->lod_lmv_failout)
                                break;

                        goto next;
                }

                index = 0;
                do {
                        if (ent->lde_name[len] < '0' ||
                            ent->lde_name[len] > '9') {
                                CDEBUG(lod->lod_lmv_failout ? D_ERROR : D_INFO,
                                       "%s: invalid shard name %.*s with the "
                                       "FID "DFID" for the striped directory "
                                       DFID", %s\n",
                                       lod2obd(lod)->obd_name, ent->lde_namelen,
                                       ent->lde_name, PFID(&fid),
                                       PFID(lu_object_fid(&obj->do_lu)),
                                       lod->lod_lmv_failout ?
                                       "failout" : "skip");

                                if (lod->lod_lmv_failout)
                                        break;

                                goto next;
                        }

                        index = index * 10 + ent->lde_name[len++] - '0';
                } while (len < ent->lde_namelen);

                if (len == ent->lde_namelen) {
                        /* Out of LMV EA range. */
                        if (index >= stripes) {
                                CERROR("%s: the shard %.*s for the striped "
                                       "directory "DFID" is out of the known "
                                       "LMV EA range [0 - %u], failout\n",
                                       lod2obd(lod)->obd_name, ent->lde_namelen,
                                       ent->lde_name,
                                       PFID(lu_object_fid(&obj->do_lu)),
                                       stripes - 1);

                                break;
                        }

                        /* The slot has been occupied. */
                        if (!fid_is_zero(&lmv1->lmv_stripe_fids[index])) {
                                struct lu_fid fid0;

                                fid_le_to_cpu(&fid0,
                                        &lmv1->lmv_stripe_fids[index]);
                                CERROR("%s: both the shard "DFID" and "DFID
                                       " for the striped directory "DFID
                                       " claim the same LMV EA slot at the "
                                       "index %d, failout\n",
                                       lod2obd(lod)->obd_name,
                                       PFID(&fid0), PFID(&fid),
                                       PFID(lu_object_fid(&obj->do_lu)), index);

                                break;
                        }

                        /* stored as LE mode */
                        lmv1->lmv_stripe_fids[index] = ent->lde_fid;

next:
                        rc = iops->next(env, it);
                }
        }

        iops->put(env, it);
        iops->fini(env, it);

        RETURN(rc > 0 ? lmv_mds_md_size(stripes, magic) : rc);
}

/**
 * Implementation of dt_object_operations::do_index_try.
 *
 * \see dt_object_operations::do_index_try() in the API description for details.
 */
static int lod_index_try(const struct lu_env *env, struct dt_object *dt,
                         const struct dt_index_features *feat)
{
        struct lod_object       *lo = lod_dt_obj(dt);
        struct dt_object        *next = dt_object_child(dt);
        int                     rc;
        ENTRY;

        LASSERT(next->do_ops);
        LASSERT(next->do_ops->do_index_try);

        rc = lod_striping_load(env, lo);
        if (rc != 0)
                RETURN(rc);

        rc = next->do_ops->do_index_try(env, next, feat);
        if (rc != 0)
                RETURN(rc);

        if (lo->ldo_dir_stripe_count > 0) {
                int i;

                for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                        if (!lo->ldo_stripe[i])
                                continue;
                        if (!dt_object_exists(lo->ldo_stripe[i]))
                                continue;
                        rc = lo->ldo_stripe[i]->do_ops->do_index_try(env,
                                                lo->ldo_stripe[i], feat);
                        if (rc != 0)
                                RETURN(rc);
                }
                dt->do_index_ops = &lod_striped_index_ops;
        } else {
                dt->do_index_ops = &lod_index_ops;
        }

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_read_lock.
 *
 * \see dt_object_operations::do_read_lock() in the API description for details.
 */
static void lod_read_lock(const struct lu_env *env, struct dt_object *dt,
                          unsigned role)
{
        dt_read_lock(env, dt_object_child(dt), role);
}

/**
 * Implementation of dt_object_operations::do_write_lock.
 *
 * \see dt_object_operations::do_write_lock() in the API description for
 * details.
 */
static void lod_write_lock(const struct lu_env *env, struct dt_object *dt,
                           unsigned role)
{
        dt_write_lock(env, dt_object_child(dt), role);
}

/**
 * Implementation of dt_object_operations::do_read_unlock.
 *
 * \see dt_object_operations::do_read_unlock() in the API description for
 * details.
 */
static void lod_read_unlock(const struct lu_env *env, struct dt_object *dt)
{
        dt_read_unlock(env, dt_object_child(dt));
}

/**
 * Implementation of dt_object_operations::do_write_unlock.
 *
 * \see dt_object_operations::do_write_unlock() in the API description for
 * details.
 */
static void lod_write_unlock(const struct lu_env *env, struct dt_object *dt)
{
        dt_write_unlock(env, dt_object_child(dt));
}

/**
 * Implementation of dt_object_operations::do_write_locked.
 *
 * \see dt_object_operations::do_write_locked() in the API description for
 * details.
 */
static int lod_write_locked(const struct lu_env *env, struct dt_object *dt)
{
        return dt_write_locked(env, dt_object_child(dt));
}

/**
 * Implementation of dt_object_operations::do_attr_get.
 *
 * \see dt_object_operations::do_attr_get() in the API description for details.
 */
static int lod_attr_get(const struct lu_env *env,
                        struct dt_object *dt,
                        struct lu_attr *attr)
{
        /* Note: for striped directory, client will merge attributes
         * from all of the sub-stripes see lmv_merge_attr(), and there
         * no MDD logic depend on directory nlink/size/time, so we can
         * always use master inode nlink and size for now. */
        return dt_attr_get(env, dt_object_child(dt), attr);
}

static inline void lod_adjust_stripe_info(struct lod_layout_component *comp,
                                          struct lov_desc *desc)
{
        if (comp->llc_pattern != LOV_PATTERN_MDT) {
                if (!comp->llc_stripe_count)
                        comp->llc_stripe_count =
                                desc->ld_default_stripe_count;
        }
        if (comp->llc_stripe_size <= 0)
                comp->llc_stripe_size = desc->ld_default_stripe_size;
}

int lod_obj_for_each_stripe(const struct lu_env *env, struct lod_object *lo,
                            struct thandle *th,
                            struct lod_obj_stripe_cb_data *data)
{
        struct lod_layout_component *lod_comp;
        int i, j, rc;
        ENTRY;

        LASSERT(lo->ldo_comp_cnt != 0 && lo->ldo_comp_entries != NULL);
        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                lod_comp = &lo->ldo_comp_entries[i];

                if (lod_comp->llc_stripe == NULL)
                        continue;

                /* has stripe but not inited yet, this component has been
                 * declared to be created, but hasn't created yet.
                 */
                if (!lod_comp_inited(lod_comp))
                        continue;

                if (data->locd_comp_skip_cb &&
                    data->locd_comp_skip_cb(env, lo, i, data))
                        continue;

                if (data->locd_comp_cb) {
                        rc = data->locd_comp_cb(env, lo, i, data);
                        if (rc)
                                RETURN(rc);
                }

                /* could used just to do sth about component, not each
                 * stripes
                 */
                if (!data->locd_stripe_cb)
                        continue;

                LASSERT(lod_comp->llc_stripe_count > 0);
                for (j = 0; j < lod_comp->llc_stripe_count; j++) {
                        struct dt_object *dt = lod_comp->llc_stripe[j];

                        if (dt == NULL)
                                continue;
                        rc = data->locd_stripe_cb(env, lo, dt, th, i, j, data);
                        if (rc != 0)
                                RETURN(rc);
                }
        }
        RETURN(0);
}

static bool lod_obj_attr_set_comp_skip_cb(const struct lu_env *env,
                struct lod_object *lo, int comp_idx,
                struct lod_obj_stripe_cb_data *data)
{
        struct lod_layout_component *lod_comp = &lo->ldo_comp_entries[comp_idx];
        bool skipped = false;

        if (!(data->locd_attr->la_valid & LA_LAYOUT_VERSION))
                return skipped;

        switch (lo->ldo_flr_state) {
        case LCM_FL_WRITE_PENDING: {
                int i;

                /* skip stale components */
                if (lod_comp->llc_flags & LCME_FL_STALE) {
                        skipped = true;
                        break;
                }

                /* skip valid and overlapping components, therefore any
                 * attempts to write overlapped components will never succeed
                 * because client will get EINPROGRESS. */
                for (i = 0; i < lo->ldo_comp_cnt; i++) {
                        if (i == comp_idx)
                                continue;

                        if (lo->ldo_comp_entries[i].llc_flags & LCME_FL_STALE)
                                continue;

                        if (lu_extent_is_overlapped(&lod_comp->llc_extent,
                                        &lo->ldo_comp_entries[i].llc_extent)) {
                                skipped = true;
                                break;
                        }
                }
                break;
        }
        default:
                LASSERTF(0, "impossible: %d\n", lo->ldo_flr_state);
        case LCM_FL_SYNC_PENDING:
                break;
        }

        CDEBUG(D_LAYOUT, DFID": %s to set component %x to version: %u\n",
               PFID(lu_object_fid(&lo->ldo_obj.do_lu)),
               skipped ? "skipped" : "chose", lod_comp->llc_id,
               data->locd_attr->la_layout_version);

        return skipped;
}

static inline int
lod_obj_stripe_attr_set_cb(const struct lu_env *env, struct lod_object *lo,
                           struct dt_object *dt, struct thandle *th,
                           int comp_idx, int stripe_idx,
                           struct lod_obj_stripe_cb_data *data)
{
        if (data->locd_declare)
                return lod_sub_declare_attr_set(env, dt, data->locd_attr, th);

        if (data->locd_attr->la_valid & LA_LAYOUT_VERSION) {
                CDEBUG(D_LAYOUT, DFID": set layout version: %u, comp_idx: %d\n",
                       PFID(lu_object_fid(&dt->do_lu)),
                       data->locd_attr->la_layout_version, comp_idx);
        }

        return lod_sub_attr_set(env, dt, data->locd_attr, th);
}

/**
 * Implementation of dt_object_operations::do_declare_attr_set.
 *
 * If the object is striped, then apply the changes to all the stripes.
 *
 * \see dt_object_operations::do_declare_attr_set() in the API description
 * for details.
 */
static int lod_declare_attr_set(const struct lu_env *env,
                                struct dt_object *dt,
                                const struct lu_attr *attr,
                                struct thandle *th)
{
        struct dt_object  *next = dt_object_child(dt);
        struct lod_object *lo = lod_dt_obj(dt);
        int                rc, i;
        ENTRY;

        /*
         * declare setattr on the local object
         */
        rc = lod_sub_declare_attr_set(env, next, attr, th);
        if (rc)
                RETURN(rc);

        /* osp_declare_attr_set() ignores all attributes other than
         * UID, GID, PROJID, and size, and osp_attr_set() ignores all
         * but UID, GID and PROJID. Declaration of size attr setting
         * happens through lod_declare_init_size(), and not through
         * this function. Therefore we need not load striping unless
         * ownership is changing.  This should save memory and (we hope)
         * speed up rename().
         */
        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
                if (!(attr->la_valid & LA_REMOTE_ATTR_SET))
                        RETURN(rc);

                if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_OWNER))
                        RETURN(0);
        } else {
                if (!(attr->la_valid & (LA_UID | LA_GID | LA_PROJID | LA_MODE |
                                        LA_ATIME | LA_MTIME | LA_CTIME |
                                        LA_FLAGS)))
                        RETURN(rc);
        }
        /*
         * load striping information, notice we don't do this when object
         * is being initialized as we don't need this information till
         * few specific cases like destroy, chown
         */
        rc = lod_striping_load(env, lo);
        if (rc)
                RETURN(rc);

        if (!lod_obj_is_striped(dt))
                RETURN(0);

        /*
         * if object is striped declare changes on the stripes
         */
        if (S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
                LASSERT(lo->ldo_stripe);
                for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                        if (lo->ldo_stripe[i] == NULL)
                                continue;
                        if (!dt_object_exists(lo->ldo_stripe[i]))
                                continue;
                        rc = lod_sub_declare_attr_set(env, lo->ldo_stripe[i],
                                                      attr, th);
                        if (rc != 0)
                                RETURN(rc);
                }
        } else {
                struct lod_obj_stripe_cb_data data = { { 0 } };

                data.locd_attr = attr;
                data.locd_declare = true;
                data.locd_stripe_cb = lod_obj_stripe_attr_set_cb;
                rc = lod_obj_for_each_stripe(env, lo, th, &data);
        }

        if (rc)
                RETURN(rc);

        if (!dt_object_exists(next) || dt_object_remote(next) ||
            !S_ISREG(attr->la_mode))
                RETURN(0);

        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_STRIPE)) {
                rc = lod_sub_declare_xattr_del(env, next, XATTR_NAME_LOV, th);
                RETURN(rc);
        }

        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_CHANGE_STRIPE) ||
            OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_PFL_RANGE)) {
                struct lod_thread_info *info = lod_env_info(env);
                struct lu_buf *buf = &info->lti_buf;

                buf->lb_buf = info->lti_ea_store;
                buf->lb_len = info->lti_ea_store_size;
                rc = lod_sub_declare_xattr_set(env, next, buf, XATTR_NAME_LOV,
                                               LU_XATTR_REPLACE, th);
        }

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_attr_set.
 *
 * If the object is striped, then apply the changes to all or subset of
 * the stripes depending on the object type and specific attributes.
 *
 * \see dt_object_operations::do_attr_set() in the API description for details.
 */
static int lod_attr_set(const struct lu_env *env,
                        struct dt_object *dt,
                        const struct lu_attr *attr,
                        struct thandle *th)
{
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
        int                     rc, i;
        ENTRY;

        /*
         * apply changes to the local object
         */
        rc = lod_sub_attr_set(env, next, attr, th);
        if (rc)
                RETURN(rc);

        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
                if (!(attr->la_valid & LA_REMOTE_ATTR_SET))
                        RETURN(rc);

                if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_OWNER))
                        RETURN(0);
        } else {
                if (!(attr->la_valid & (LA_UID | LA_GID | LA_MODE | LA_PROJID |
                                        LA_ATIME | LA_MTIME | LA_CTIME |
                                        LA_FLAGS)))
                        RETURN(rc);
        }

        /* FIXME: a tricky case in the code path of mdd_layout_change():
         * the in-memory striping information has been freed in lod_xattr_set()
         * due to layout change. It has to load stripe here again. It only
         * changes flags of layout so declare_attr_set() is still accurate */
        rc = lod_striping_load(env, lo);
        if (rc)
                RETURN(rc);

        if (!lod_obj_is_striped(dt))
                RETURN(0);

        /*
         * if object is striped, apply changes to all the stripes
         */
        if (S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
                LASSERT(lo->ldo_stripe);
                for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                        if (unlikely(lo->ldo_stripe[i] == NULL))
                                continue;

                        if ((dt_object_exists(lo->ldo_stripe[i]) == 0))
                                continue;

                        rc = lod_sub_attr_set(env, lo->ldo_stripe[i], attr, th);
                        if (rc != 0)
                                break;
                }
        } else {
                struct lod_obj_stripe_cb_data data = { { 0 } };

                data.locd_attr = attr;
                data.locd_declare = false;
                data.locd_comp_skip_cb = lod_obj_attr_set_comp_skip_cb;
                data.locd_stripe_cb = lod_obj_stripe_attr_set_cb;
                rc = lod_obj_for_each_stripe(env, lo, th, &data);
        }

        if (rc)
                RETURN(rc);

        if (!dt_object_exists(next) || dt_object_remote(next) ||
            !S_ISREG(attr->la_mode))
                RETURN(0);

        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_STRIPE)) {
                rc = lod_sub_xattr_del(env, next, XATTR_NAME_LOV, th);
                RETURN(rc);
        }

        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_CHANGE_STRIPE)) {
                struct lod_thread_info *info = lod_env_info(env);
                struct lu_buf *buf = &info->lti_buf;
                struct ost_id *oi = &info->lti_ostid;
                struct lu_fid *fid = &info->lti_fid;
                struct lov_mds_md_v1 *lmm;
                struct lov_ost_data_v1 *objs;
                __u32 magic;

                rc = lod_get_lov_ea(env, lo);
                if (rc <= 0)
                        RETURN(rc);

                buf->lb_buf = info->lti_ea_store;
                buf->lb_len = info->lti_ea_store_size;
                lmm = info->lti_ea_store;
                magic = le32_to_cpu(lmm->lmm_magic);
                if (magic == LOV_MAGIC_COMP_V1 || magic == LOV_MAGIC_SEL) {
                        struct lov_comp_md_v1 *lcm = buf->lb_buf;
                        struct lov_comp_md_entry_v1 *lcme =
                                                &lcm->lcm_entries[0];

                        lmm = buf->lb_buf + le32_to_cpu(lcme->lcme_offset);
                        magic = le32_to_cpu(lmm->lmm_magic);
                }

                if (magic == LOV_MAGIC_V1)
                        objs = &(lmm->lmm_objects[0]);
                else
                        objs = &((struct lov_mds_md_v3 *)lmm)->lmm_objects[0];
                ostid_le_to_cpu(&objs->l_ost_oi, oi);
                ostid_to_fid(fid, oi, le32_to_cpu(objs->l_ost_idx));
                fid->f_oid--;
                fid_to_ostid(fid, oi);
                ostid_cpu_to_le(oi, &objs->l_ost_oi);

                rc = lod_sub_xattr_set(env, next, buf, XATTR_NAME_LOV,
                                       LU_XATTR_REPLACE, th);
        } else if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_PFL_RANGE)) {
                struct lod_thread_info *info = lod_env_info(env);
                struct lu_buf *buf = &info->lti_buf;
                struct lov_comp_md_v1 *lcm;
                struct lov_comp_md_entry_v1 *lcme;

                rc = lod_get_lov_ea(env, lo);
                if (rc <= 0)
                        RETURN(rc);

                buf->lb_buf = info->lti_ea_store;
                buf->lb_len = info->lti_ea_store_size;
                lcm = buf->lb_buf;
                if (le32_to_cpu(lcm->lcm_magic) != LOV_MAGIC_COMP_V1 &&
                    le32_to_cpu(lcm->lcm_magic) != LOV_MAGIC_SEL)
                        RETURN(-EINVAL);

                le32_add_cpu(&lcm->lcm_layout_gen, 1);
                lcme = &lcm->lcm_entries[0];
                le64_add_cpu(&lcme->lcme_extent.e_start, 1);
                le64_add_cpu(&lcme->lcme_extent.e_end, -1);

                rc = lod_sub_xattr_set(env, next, buf, XATTR_NAME_LOV,
                                       LU_XATTR_REPLACE, th);
        }

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_xattr_get.
 *
 * If LOV EA is requested from the root object and it's not
 * found, then return default striping for the filesystem.
 *
 * \see dt_object_operations::do_xattr_get() in the API description for details.
 */
static int lod_xattr_get(const struct lu_env *env, struct dt_object *dt,
                         struct lu_buf *buf, const char *name)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_device *dev = lu2lod_dev(dt->do_lu.lo_dev);
        int is_root;
        int rc;
        ENTRY;

        rc = dt_xattr_get(env, dt_object_child(dt), buf, name);
        if (strcmp(name, XATTR_NAME_LMV) == 0) {
                struct lmv_mds_md_v1    *lmv1;
                struct lmv_foreign_md   *lfm;
                int                      rc1 = 0;

                if (rc > (typeof(rc))sizeof(*lmv1))
                        RETURN(rc);

                /* short (<= sizeof(struct lmv_mds_md_v1)) foreign LMV case */
                /* XXX empty foreign LMV is not allowed */
                if (rc <= offsetof(typeof(*lfm), lfm_value))
                        RETURN(rc = rc > 0 ? -EINVAL : rc);

                if (buf->lb_buf == NULL || buf->lb_len == 0) {
                        CLASSERT(sizeof(*lmv1) <= sizeof(info->lti_key));

                        /* lti_buf is large enough for *lmv1 or a short
                         * (<= sizeof(struct lmv_mds_md_v1)) foreign LMV
                         */
                        info->lti_buf.lb_buf = info->lti_key;
                        info->lti_buf.lb_len = sizeof(*lmv1);
                        rc = dt_xattr_get(env, dt_object_child(dt),
                                          &info->lti_buf, name);
                        if (unlikely(rc <= offsetof(typeof(*lfm),
                                                    lfm_value)))
                                RETURN(rc = rc > 0 ? -EINVAL : rc);

                        lfm = info->lti_buf.lb_buf;
                        if (le32_to_cpu(lfm->lfm_magic) == LMV_MAGIC_FOREIGN)
                                RETURN(rc);

                        if (unlikely(rc != sizeof(*lmv1)))
                                RETURN(rc = rc > 0 ? -EINVAL : rc);

                        lmv1 = info->lti_buf.lb_buf;
                        /* The on-disk LMV EA only contains header, but the
                         * returned LMV EA size should contain the space for
                         * the FIDs of all shards of the striped directory. */
                        if (le32_to_cpu(lmv1->lmv_magic) == LMV_MAGIC_V1)
                                rc = lmv_mds_md_size(
                                        le32_to_cpu(lmv1->lmv_stripe_count),
                                        LMV_MAGIC_V1);
                } else {
                        lfm = buf->lb_buf;
                        if (le32_to_cpu(lfm->lfm_magic) == LMV_MAGIC_FOREIGN)
                                RETURN(rc);

                        if (rc != sizeof(*lmv1))
                                RETURN(rc = rc > 0 ? -EINVAL : rc);

                        rc1 = lod_load_lmv_shards(env, lod_dt_obj(dt),
                                                  buf, false);
                }

                RETURN(rc = rc1 != 0 ? rc1 : rc);
        }

        if ((rc > 0) && buf->lb_buf && strcmp(name, XATTR_NAME_LOV) == 0) {
                struct lov_comp_md_v1 *lcm = buf->lb_buf;

                if (lcm->lcm_magic == cpu_to_le32(LOV_MAGIC_SEL))
                        lcm->lcm_magic = cpu_to_le32(LOV_MAGIC_COMP_V1);
        }

        if (rc != -ENODATA || !S_ISDIR(dt->do_lu.lo_header->loh_attr & S_IFMT))
                RETURN(rc);

        /*
         * XXX: Only used by lfsck
         *
         * lod returns default striping on the real root of the device
         * this is like the root stores default striping for the whole
         * filesystem. historically we've been using a different approach
         * and store it in the config.
         */
        dt_root_get(env, dev->lod_child, &info->lti_fid);
        is_root = lu_fid_eq(&info->lti_fid, lu_object_fid(&dt->do_lu));

        if (is_root && strcmp(XATTR_NAME_LOV, name) == 0) {
                struct lov_user_md *lum = buf->lb_buf;
                struct lov_desc    *desc = &dev->lod_desc;

                if (buf->lb_buf == NULL) {
                        rc = sizeof(*lum);
                } else if (buf->lb_len >= sizeof(*lum)) {
                        lum->lmm_magic = cpu_to_le32(LOV_USER_MAGIC_V1);
                        lmm_oi_set_seq(&lum->lmm_oi, FID_SEQ_LOV_DEFAULT);
                        lmm_oi_set_id(&lum->lmm_oi, 0);
                        lmm_oi_cpu_to_le(&lum->lmm_oi, &lum->lmm_oi);
                        lum->lmm_pattern = cpu_to_le32(desc->ld_pattern);
                        lum->lmm_stripe_size = cpu_to_le32(
                                                desc->ld_default_stripe_size);
                        lum->lmm_stripe_count = cpu_to_le16(
                                                desc->ld_default_stripe_count);
                        lum->lmm_stripe_offset = cpu_to_le16(
                                                desc->ld_default_stripe_offset);
                        rc = sizeof(*lum);
                } else {
                        rc = -ERANGE;
                }
        }

        RETURN(rc);
}

/**
 * Verify LVM EA.
 *
 * Checks that the magic of the stripe is sane.
 *
 * \param[in] lod       lod device
 * \param[in] lum       a buffer storing LMV EA to verify
 *
 * \retval              0 if the EA is sane
 * \retval              negative otherwise
 */
static int lod_verify_md_striping(struct lod_device *lod,
                                  const struct lmv_user_md_v1 *lum)
{
        if (unlikely(le32_to_cpu(lum->lum_magic) != LMV_USER_MAGIC)) {
                CERROR("%s: invalid lmv_user_md: magic = %x, "
                       "stripe_offset = %d, stripe_count = %u: rc = %d\n",
                       lod2obd(lod)->obd_name, le32_to_cpu(lum->lum_magic),
                       (int)le32_to_cpu(lum->lum_stripe_offset),
                       le32_to_cpu(lum->lum_stripe_count), -EINVAL);
                return -EINVAL;
        }

        return 0;
}

/**
 * Initialize LMV EA for a slave.
 *
 * Initialize slave's LMV EA from the master's LMV EA.
 *
 * \param[in] master_lmv        a buffer containing master's EA
 * \param[out] slave_lmv        a buffer where slave's EA will be stored
 *
 */
static void lod_prep_slave_lmv_md(struct lmv_mds_md_v1 *slave_lmv,
                                  const struct lmv_mds_md_v1 *master_lmv)
{
        *slave_lmv = *master_lmv;
        slave_lmv->lmv_magic = cpu_to_le32(LMV_MAGIC_STRIPE);
}

/**
 * Generate LMV EA.
 *
 * Generate LMV EA from the object passed as \a dt. The object must have
 * the stripes created and initialized.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[out] lmv_buf  buffer storing generated LMV EA
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_prep_lmv_md(const struct lu_env *env, struct dt_object *dt,
                           struct lu_buf *lmv_buf)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_device       *lod = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_object       *lo = lod_dt_obj(dt);
        struct lmv_mds_md_v1    *lmm1;
        int                     stripe_count;
        int                     type = LU_SEQ_RANGE_ANY;
        int                     rc;
        __u32                   mdtidx;
        ENTRY;

        LASSERT(lo->ldo_dir_striped != 0);
        LASSERT(lo->ldo_dir_stripe_count > 0);
        stripe_count = lo->ldo_dir_stripe_count;
        /* Only store the LMV EA heahder on the disk. */
        if (info->lti_ea_store_size < sizeof(*lmm1)) {
                rc = lod_ea_store_resize(info, sizeof(*lmm1));
                if (rc != 0)
                        RETURN(rc);
        } else {
                memset(info->lti_ea_store, 0, sizeof(*lmm1));
        }

        lmm1 = (struct lmv_mds_md_v1 *)info->lti_ea_store;
        memset(lmm1, 0, sizeof(*lmm1));
        lmm1->lmv_magic = cpu_to_le32(LMV_MAGIC);
        lmm1->lmv_stripe_count = cpu_to_le32(stripe_count);
        lmm1->lmv_hash_type = cpu_to_le32(lo->ldo_dir_hash_type);
        if (lo->ldo_dir_hash_type & LMV_HASH_FLAG_MIGRATION) {
                lmm1->lmv_migrate_hash = cpu_to_le32(lo->ldo_dir_migrate_hash);
                lmm1->lmv_migrate_offset =
                        cpu_to_le32(lo->ldo_dir_migrate_offset);
        }
        rc = lod_fld_lookup(env, lod, lu_object_fid(&dt->do_lu),
                            &mdtidx, &type);
        if (rc != 0)
                RETURN(rc);

        lmm1->lmv_master_mdt_index = cpu_to_le32(mdtidx);
        lmv_buf->lb_buf = info->lti_ea_store;
        lmv_buf->lb_len = sizeof(*lmm1);

        RETURN(rc);
}

/**
 * Create in-core represenation for a striped directory.
 *
 * Parse the buffer containing LMV EA and instantiate LU objects
 * representing the stripe objects. The pointers to the objects are
 * stored in ldo_stripe field of \a lo. This function is used when
 * we need to access an already created object (i.e. load from a disk).
 *
 * \param[in] env       execution environment
 * \param[in] lo        lod object
 * \param[in] buf       buffer containing LMV EA
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
int lod_parse_dir_striping(const struct lu_env *env, struct lod_object *lo,
                           const struct lu_buf *buf)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_device       *lod = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        struct lod_tgt_descs    *ltd = &lod->lod_mdt_descs;
        struct dt_object        **stripe;
        union lmv_mds_md        *lmm = buf->lb_buf;
        struct lmv_mds_md_v1    *lmv1 = &lmm->lmv_md_v1;
        struct lu_fid           *fid = &info->lti_fid;
        unsigned int            i;
        int                     rc = 0;
        ENTRY;

        LASSERT(mutex_is_locked(&lo->ldo_layout_mutex));

        /* XXX may be useless as not called for foreign LMV ?? */
        if (le32_to_cpu(lmv1->lmv_magic) == LMV_MAGIC_FOREIGN)
                RETURN(0);

        if (le32_to_cpu(lmv1->lmv_magic) == LMV_MAGIC_STRIPE) {
                lo->ldo_dir_slave_stripe = 1;
                RETURN(0);
        }

        if (le32_to_cpu(lmv1->lmv_magic) != LMV_MAGIC_V1)
                RETURN(-EINVAL);

        if (le32_to_cpu(lmv1->lmv_stripe_count) < 1)
                RETURN(0);

        LASSERT(lo->ldo_stripe == NULL);
        OBD_ALLOC(stripe, sizeof(stripe[0]) *
                  (le32_to_cpu(lmv1->lmv_stripe_count)));
        if (stripe == NULL)
                RETURN(-ENOMEM);

        for (i = 0; i < le32_to_cpu(lmv1->lmv_stripe_count); i++) {
                struct dt_device        *tgt_dt;
                struct dt_object        *dto;
                int                     type = LU_SEQ_RANGE_ANY;
                __u32                   idx;

                fid_le_to_cpu(fid, &lmv1->lmv_stripe_fids[i]);
                if (!fid_is_sane(fid)) {
                        stripe[i] = NULL;
                        continue;
                }

                rc = lod_fld_lookup(env, lod, fid, &idx, &type);
                if (rc != 0)
                        GOTO(out, rc);

                if (idx == lod2lu_dev(lod)->ld_site->ld_seq_site->ss_node_id) {
                        tgt_dt = lod->lod_child;
                } else {
                        struct lod_tgt_desc     *tgt;

                        tgt = LTD_TGT(ltd, idx);
                        if (tgt == NULL)
                                GOTO(out, rc = -ESTALE);
                        tgt_dt = tgt->ltd_tgt;
                }

                dto = dt_locate_at(env, tgt_dt, fid,
                                  lo->ldo_obj.do_lu.lo_dev->ld_site->ls_top_dev,
                                  NULL);
                if (IS_ERR(dto))
                        GOTO(out, rc = PTR_ERR(dto));

                stripe[i] = dto;
        }
out:
        lo->ldo_stripe = stripe;
        lo->ldo_dir_stripe_count = le32_to_cpu(lmv1->lmv_stripe_count);
        lo->ldo_dir_stripes_allocated = le32_to_cpu(lmv1->lmv_stripe_count);
        if (rc != 0)
                lod_striping_free_nolock(env, lo);

        RETURN(rc);
}

/**
 * Declare create a striped directory.
 *
 * Declare creating a striped directory with a given stripe pattern on the
 * specified MDTs. A striped directory is represented as a regular directory
 * - an index listing all the stripes. The stripes point back to the master
 * object with ".." and LinkEA. The master object gets LMV EA which
 * identifies it as a striped directory. The function allocates FIDs
 * for all stripes.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] attr      attributes to initialize the objects with
 * \param[in] dof       type of objects to be created
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_dir_declare_create_stripes(const struct lu_env *env,
                                          struct dt_object *dt,
                                          struct lu_attr *attr,
                                          struct dt_object_format *dof,
                                          struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct lu_buf           lmv_buf;
        struct lu_buf           slave_lmv_buf;
        struct lmv_mds_md_v1    *lmm;
        struct lmv_mds_md_v1    *slave_lmm = NULL;
        struct dt_insert_rec    *rec = &info->lti_dt_rec;
        struct lod_object       *lo = lod_dt_obj(dt);
        int                     rc;
        __u32                   i;
        ENTRY;

        rc = lod_prep_lmv_md(env, dt, &lmv_buf);
        if (rc != 0)
                GOTO(out, rc);
        lmm = lmv_buf.lb_buf;

        OBD_ALLOC_PTR(slave_lmm);
        if (slave_lmm == NULL)
                GOTO(out, rc = -ENOMEM);

        lod_prep_slave_lmv_md(slave_lmm, lmm);
        slave_lmv_buf.lb_buf = slave_lmm;
        slave_lmv_buf.lb_len = sizeof(*slave_lmm);

        if (!dt_try_as_dir(env, dt_object_child(dt)))
                GOTO(out, rc = -EINVAL);

        rec->rec_type = S_IFDIR;
        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                struct dt_object        *dto = lo->ldo_stripe[i];
                char                    *stripe_name = info->lti_key;
                struct lu_name          *sname;
                struct linkea_data       ldata          = { NULL };
                struct lu_buf           linkea_buf;

                /* OBD_FAIL_MDS_STRIPE_FID may leave stripe uninitialized */
                if (!dto)
                        continue;

                rc = lod_sub_declare_create(env, dto, attr, NULL, dof, th);
                if (rc != 0)
                        GOTO(out, rc);

                if (!dt_try_as_dir(env, dto))
                        GOTO(out, rc = -EINVAL);

                rc = lod_sub_declare_ref_add(env, dto, th);
                if (rc != 0)
                        GOTO(out, rc);

                rec->rec_fid = lu_object_fid(&dto->do_lu);
                rc = lod_sub_declare_insert(env, dto,
                                            (const struct dt_rec *)rec,
                                            (const struct dt_key *)dot, th);
                if (rc != 0)
                        GOTO(out, rc);

                /* master stripe FID will be put to .. */
                rec->rec_fid = lu_object_fid(&dt->do_lu);
                rc = lod_sub_declare_insert(env, dto,
                                            (const struct dt_rec *)rec,
                                            (const struct dt_key *)dotdot, th);
                if (rc != 0)
                        GOTO(out, rc);

                if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_SLAVE_LMV) ||
                    cfs_fail_val != i) {
                        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_SLAVE_LMV) &&
                            cfs_fail_val == i)
                                slave_lmm->lmv_master_mdt_index =
                                                        cpu_to_le32(i + 1);
                        else
                                slave_lmm->lmv_master_mdt_index =
                                                        cpu_to_le32(i);
                        rc = lod_sub_declare_xattr_set(env, dto, &slave_lmv_buf,
                                                       XATTR_NAME_LMV, 0, th);
                        if (rc != 0)
                                GOTO(out, rc);
                }

                if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_SLAVE_NAME) &&
                    cfs_fail_val == i)
                        snprintf(stripe_name, sizeof(info->lti_key), DFID":%u",
                                PFID(lu_object_fid(&dto->do_lu)), i + 1);
                else
                        snprintf(stripe_name, sizeof(info->lti_key), DFID":%u",
                                PFID(lu_object_fid(&dto->do_lu)), i);

                sname = lod_name_get(env, stripe_name, strlen(stripe_name));
                rc = linkea_links_new(&ldata, &info->lti_linkea_buf,
                                      sname, lu_object_fid(&dt->do_lu));
                if (rc != 0)
                        GOTO(out, rc);

                linkea_buf.lb_buf = ldata.ld_buf->lb_buf;
                linkea_buf.lb_len = ldata.ld_leh->leh_len;
                rc = lod_sub_declare_xattr_set(env, dto, &linkea_buf,
                                               XATTR_NAME_LINK, 0, th);
                if (rc != 0)
                        GOTO(out, rc);

                rec->rec_fid = lu_object_fid(&dto->do_lu);
                rc = lod_sub_declare_insert(env, dt_object_child(dt),
                                            (const struct dt_rec *)rec,
                                            (const struct dt_key *)stripe_name,
                                            th);
                if (rc != 0)
                        GOTO(out, rc);

                rc = lod_sub_declare_ref_add(env, dt_object_child(dt), th);
                if (rc != 0)
                        GOTO(out, rc);
        }

        rc = lod_sub_declare_xattr_set(env, dt_object_child(dt),
                                       &lmv_buf, XATTR_NAME_LMV, 0, th);
        if (rc != 0)
                GOTO(out, rc);
out:
        if (slave_lmm != NULL)
                OBD_FREE_PTR(slave_lmm);

        RETURN(rc);
}

static int lod_prep_md_striped_create(const struct lu_env *env,
                                      struct dt_object *dt,
                                      struct lu_attr *attr,
                                      const struct lmv_user_md_v1 *lum,
                                      struct dt_object_format *dof,
                                      struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_device       *lod = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_tgt_descs    *ltd = &lod->lod_mdt_descs;
        struct lod_object       *lo = lod_dt_obj(dt);
        struct dt_object        **stripe;
        __u32                   stripe_count;
        int                     *idx_array;
        __u32                   master_index;
        int                     rc = 0;
        __u32                   i;
        __u32                   j;
        bool                    is_specific = false;
        ENTRY;

        /* The lum has been verifed in lod_verify_md_striping */
        LASSERT(le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC ||
                le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC_SPECIFIC);

        stripe_count = lo->ldo_dir_stripe_count;

        OBD_ALLOC(idx_array, sizeof(idx_array[0]) * stripe_count);
        if (idx_array == NULL)
                RETURN(-ENOMEM);

        OBD_ALLOC(stripe, sizeof(stripe[0]) * stripe_count);
        if (stripe == NULL)
                GOTO(out_free, rc = -ENOMEM);

        /* Start index must be the master MDT */
        master_index = lu_site2seq(lod2lu_dev(lod)->ld_site)->ss_node_id;
        idx_array[0] = master_index;
        if (le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC_SPECIFIC) {
                is_specific = true;
                for (i = 1; i < stripe_count; i++)
                        idx_array[i] = le32_to_cpu(lum->lum_objects[i].lum_mds);
        }

        for (i = 0; i < stripe_count; i++) {
                struct lod_tgt_desc     *tgt = NULL;
                struct dt_object        *dto;
                struct lu_fid           fid = { 0 };
                int                     idx;
                struct lu_object_conf   conf = { 0 };
                struct dt_device        *tgt_dt = NULL;

                /* Try to find next avaible target */
                idx = idx_array[i];
                for (j = 0; j < lod->lod_remote_mdt_count;
                     j++, idx = (idx + 1) % (lod->lod_remote_mdt_count + 1)) {
                        bool already_allocated = false;
                        __u32 k;

                        CDEBUG(D_INFO, "try idx %d, mdt cnt %u, allocated %u\n",
                               idx, lod->lod_remote_mdt_count + 1, i);

                        if (likely(!is_specific &&
                                   !OBD_FAIL_CHECK(OBD_FAIL_LARGE_STRIPE))) {
                                /* check whether the idx already exists
                                 * in current allocated array */
                                for (k = 0; k < i; k++) {
                                        if (idx_array[k] == idx) {
                                                already_allocated = true;
                                                break;
                                        }
                                }

                                if (already_allocated)
                                        continue;
                        }

                        /* Sigh, this index is not in the bitmap, let's check
                         * next available target */
                        if (!cfs_bitmap_check(ltd->ltd_tgt_bitmap, idx) &&
                            idx != master_index)
                                continue;

                        if (idx == master_index) {
                                /* Allocate the FID locally */
                                rc = obd_fid_alloc(env, lod->lod_child_exp,
                                                   &fid, NULL);
                                if (rc < 0)
                                        GOTO(out_put, rc);
                                tgt_dt = lod->lod_child;
                                break;
                        }

                        /* check the status of the OSP */
                        tgt = LTD_TGT(ltd, idx);
                        if (tgt == NULL)
                                continue;

                        tgt_dt = tgt->ltd_tgt;
                        rc = dt_statfs(env, tgt_dt, &info->lti_osfs, NULL);
                        if (rc) {
                                /* this OSP doesn't feel well */
                                rc = 0;
                                continue;
                        }

                        rc = obd_fid_alloc(env, tgt->ltd_exp, &fid, NULL);
                        if (rc < 0) {
                                rc = 0;
                                continue;
                        }

                        break;
                }

                /* Can not allocate more stripes */
                if (j == lod->lod_remote_mdt_count) {
                        CDEBUG(D_INFO, "%s: require stripes %u only get %d\n",
                               lod2obd(lod)->obd_name, stripe_count, i);
                        break;
                }

                CDEBUG(D_INFO, "Get idx %d, for stripe %d "DFID"\n",
                       idx, i, PFID(&fid));
                idx_array[i] = idx;
                /* Set the start index for next stripe allocation */
                if (!is_specific && i < stripe_count - 1) {
                        /*
                         * for large dir test, put all other slaves on one
                         * remote MDT, otherwise we may save too many local
                         * slave locks which will exceed RS_MAX_LOCKS.
                         */
                        if (unlikely(OBD_FAIL_CHECK(OBD_FAIL_LARGE_STRIPE)))
                                idx = master_index;
                        idx_array[i + 1] = (idx + 1) %
                                           (lod->lod_remote_mdt_count + 1);
                }
                /* tgt_dt and fid must be ready after search avaible OSP
                 * in the above loop */
                LASSERT(tgt_dt != NULL);
                LASSERT(fid_is_sane(&fid));

                /* fail a remote stripe FID allocation */
                if (i && OBD_FAIL_CHECK(OBD_FAIL_MDS_STRIPE_FID))
                        continue;

                conf.loc_flags = LOC_F_NEW;
                dto = dt_locate_at(env, tgt_dt, &fid,
                                   dt->do_lu.lo_dev->ld_site->ls_top_dev,
                                   &conf);
                if (IS_ERR(dto))
                        GOTO(out_put, rc = PTR_ERR(dto));
                stripe[i] = dto;
        }

        lo->ldo_dir_striped = 1;
        lo->ldo_stripe = stripe;
        lo->ldo_dir_stripe_count = i;
        lo->ldo_dir_stripes_allocated = stripe_count;
        smp_mb();
        lo->ldo_dir_stripe_loaded = 1;

        if (lo->ldo_dir_stripe_count == 0)
                GOTO(out_put, rc = -ENOSPC);

        rc = lod_dir_declare_create_stripes(env, dt, attr, dof, th);
        if (rc != 0)
                GOTO(out_put, rc);

out_put:
        if (rc < 0) {
                for (i = 0; i < stripe_count; i++)
                        if (stripe[i] != NULL)
                                dt_object_put(env, stripe[i]);
                OBD_FREE(stripe, sizeof(stripe[0]) * stripe_count);
                lo->ldo_dir_stripe_count = 0;
                lo->ldo_dir_stripes_allocated = 0;
                lo->ldo_stripe = NULL;
        }

out_free:
        OBD_FREE(idx_array, sizeof(idx_array[0]) * stripe_count);

        RETURN(rc);
}

/**
 *
 * Alloc cached foreign LMV
 *
 * \param[in] lo        object
 * \param[in] size      size of foreign LMV
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
int lod_alloc_foreign_lmv(struct lod_object *lo, size_t size)
{
        OBD_ALLOC_LARGE(lo->ldo_foreign_lmv, size);
        if (lo->ldo_foreign_lmv == NULL)
                return -ENOMEM;
        lo->ldo_foreign_lmv_size = size;
        lo->ldo_dir_is_foreign = 1;

        return 0;
}

/**
 * Declare create striped md object.
 *
 * The function declares intention to create a striped directory. This is a
 * wrapper for lod_prep_md_striped_create(). The only additional functionality
 * is to verify pattern \a lum_buf is good. Check that function for the details.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] attr      attributes to initialize the objects with
 * \param[in] lum_buf   a pattern specifying the number of stripes and
 *                      MDT to start from
 * \param[in] dof       type of objects to be created
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 *
 */
static int lod_declare_xattr_set_lmv(const struct lu_env *env,
                                     struct dt_object *dt,
                                     struct lu_attr *attr,
                                     const struct lu_buf *lum_buf,
                                     struct dt_object_format *dof,
                                     struct thandle *th)
{
        struct lod_object       *lo = lod_dt_obj(dt);
        struct lmv_user_md_v1   *lum = lum_buf->lb_buf;
        int                     rc;
        ENTRY;

        LASSERT(lum != NULL);

        CDEBUG(D_INFO, "lum magic = %x count = %u offset = %d\n",
               le32_to_cpu(lum->lum_magic), le32_to_cpu(lum->lum_stripe_count),
               (int)le32_to_cpu(lum->lum_stripe_offset));

        if (lo->ldo_dir_stripe_count == 0) {
                if (lo->ldo_dir_is_foreign) {
                        rc = lod_alloc_foreign_lmv(lo, lum_buf->lb_len);
                        if (rc != 0)
                                GOTO(out, rc);
                        memcpy(lo->ldo_foreign_lmv, lum, lum_buf->lb_len);
                        lo->ldo_dir_stripe_loaded = 1;
                }
                GOTO(out, rc = 0);
        }

        /* prepare dir striped objects */
        rc = lod_prep_md_striped_create(env, dt, attr, lum, dof, th);
        if (rc != 0) {
                /* failed to create striping, let's reset
                 * config so that others don't get confused */
                lod_striping_free(env, lo);
                GOTO(out, rc);
        }
out:
        RETURN(rc);
}

/**
 * Append source stripes after target stripes for migrating directory. NB, we
 * only need to declare this, the append is done inside lod_xattr_set_lmv().
 *
 * \param[in] env       execution environment
 * \param[in] dt        target object
 * \param[in] buf       LMV buf which contains source stripe fids
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_dir_declare_layout_add(const struct lu_env *env,
                                      struct dt_object *dt,
                                      const struct lu_buf *buf,
                                      struct thandle *th)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_device *lod = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_tgt_descs *ltd = &lod->lod_mdt_descs;
        struct lod_object *lo = lod_dt_obj(dt);
        struct dt_object *next = dt_object_child(dt);
        struct dt_object_format *dof = &info->lti_format;
        struct lmv_mds_md_v1 *lmv = buf->lb_buf;
        struct dt_object **stripe;
        __u32 stripe_count = le32_to_cpu(lmv->lmv_stripe_count);
        struct lu_fid *fid = &info->lti_fid;
        struct lod_tgt_desc *tgt;
        struct dt_object *dto;
        struct dt_device *tgt_dt;
        int type = LU_SEQ_RANGE_ANY;
        struct dt_insert_rec *rec = &info->lti_dt_rec;
        char *stripe_name = info->lti_key;
        struct lu_name *sname;
        struct linkea_data ldata = { NULL };
        struct lu_buf linkea_buf;
        __u32 idx;
        int i;
        int rc;

        ENTRY;

        if (le32_to_cpu(lmv->lmv_magic) != LMV_MAGIC_V1)
                RETURN(-EINVAL);

        if (stripe_count == 0)
                RETURN(-EINVAL);

        dof->dof_type = DFT_DIR;

        OBD_ALLOC(stripe,
                  sizeof(*stripe) * (lo->ldo_dir_stripe_count + stripe_count));
        if (stripe == NULL)
                RETURN(-ENOMEM);

        for (i = 0; i < lo->ldo_dir_stripe_count; i++)
                stripe[i] = lo->ldo_stripe[i];

        for (i = 0; i < stripe_count; i++) {
                fid_le_to_cpu(fid,
                        &lmv->lmv_stripe_fids[i]);
                if (!fid_is_sane(fid))
                        continue;

                rc = lod_fld_lookup(env, lod, fid, &idx, &type);
                if (rc)
                        GOTO(out, rc);

                if (idx == lod2lu_dev(lod)->ld_site->ld_seq_site->ss_node_id) {
                        tgt_dt = lod->lod_child;
                } else {
                        tgt = LTD_TGT(ltd, idx);
                        if (tgt == NULL)
                                GOTO(out, rc = -ESTALE);
                        tgt_dt = tgt->ltd_tgt;
                }

                dto = dt_locate_at(env, tgt_dt, fid,
                                  lo->ldo_obj.do_lu.lo_dev->ld_site->ls_top_dev,
                                  NULL);
                if (IS_ERR(dto))
                        GOTO(out, rc = PTR_ERR(dto));

                stripe[i + lo->ldo_dir_stripe_count] = dto;

                if (!dt_try_as_dir(env, dto))
                        GOTO(out, rc = -ENOTDIR);

                rc = lod_sub_declare_ref_add(env, dto, th);
                if (rc)
                        GOTO(out, rc);

                rc = lod_sub_declare_insert(env, dto,
                                            (const struct dt_rec *)rec,
                                            (const struct dt_key *)dot, th);
                if (rc)
                        GOTO(out, rc);

                rc = lod_sub_declare_insert(env, dto,
                                            (const struct dt_rec *)rec,
                                            (const struct dt_key *)dotdot, th);
                if (rc)
                        GOTO(out, rc);

                rc = lod_sub_declare_xattr_set(env, dto, buf,
                                                XATTR_NAME_LMV, 0, th);
                if (rc)
                        GOTO(out, rc);

                snprintf(stripe_name, sizeof(info->lti_key), DFID":%u",
                         PFID(lu_object_fid(&dto->do_lu)),
                         i + lo->ldo_dir_stripe_count);

                sname = lod_name_get(env, stripe_name, strlen(stripe_name));
                rc = linkea_links_new(&ldata, &info->lti_linkea_buf,
                                      sname, lu_object_fid(&dt->do_lu));
                if (rc)
                        GOTO(out, rc);

                linkea_buf.lb_buf = ldata.ld_buf->lb_buf;
                linkea_buf.lb_len = ldata.ld_leh->leh_len;
                rc = lod_sub_declare_xattr_set(env, dto, &linkea_buf,
                                               XATTR_NAME_LINK, 0, th);
                if (rc)
                        GOTO(out, rc);

                rc = lod_sub_declare_insert(env, next,
                                            (const struct dt_rec *)rec,
                                            (const struct dt_key *)stripe_name,
                                            th);
                if (rc)
                        GOTO(out, rc);

                rc = lod_sub_declare_ref_add(env, next, th);
                if (rc)
                        GOTO(out, rc);
        }

        if (lo->ldo_stripe)
                OBD_FREE(lo->ldo_stripe,
                         sizeof(*stripe) * lo->ldo_dir_stripes_allocated);
        lo->ldo_stripe = stripe;
        lo->ldo_dir_migrate_offset = lo->ldo_dir_stripe_count;
        lo->ldo_dir_migrate_hash = le32_to_cpu(lmv->lmv_hash_type);
        lo->ldo_dir_stripe_count += stripe_count;
        lo->ldo_dir_stripes_allocated += stripe_count;
        lo->ldo_dir_hash_type |= LMV_HASH_FLAG_MIGRATION;

        RETURN(0);
out:
        i = lo->ldo_dir_stripe_count;
        while (i < lo->ldo_dir_stripe_count + stripe_count && stripe[i])
                dt_object_put(env, stripe[i++]);

        OBD_FREE(stripe,
                 sizeof(*stripe) * (stripe_count + lo->ldo_dir_stripe_count));
        RETURN(rc);
}

static int lod_dir_declare_layout_delete(const struct lu_env *env,
                                         struct dt_object *dt,
                                         const struct lu_buf *buf,
                                         struct thandle *th)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_object *lo = lod_dt_obj(dt);
        struct dt_object *next = dt_object_child(dt);
        struct lmv_user_md *lmu = buf->lb_buf;
        __u32 final_stripe_count;
        char *stripe_name = info->lti_key;
        struct dt_object *dto;
        int i;
        int rc = 0;

        if (!lmu)
                return -EINVAL;

        final_stripe_count = le32_to_cpu(lmu->lum_stripe_count);
        if (final_stripe_count >= lo->ldo_dir_stripe_count)
                return -EINVAL;

        for (i = final_stripe_count; i < lo->ldo_dir_stripe_count; i++) {
                dto = lo->ldo_stripe[i];
                if (!dto)
                        continue;

                if (!dt_try_as_dir(env, dto))
                        return -ENOTDIR;

                rc = lod_sub_declare_delete(env, dto,
                                            (const struct dt_key *)dot, th);
                if (rc)
                        return rc;

                rc = lod_sub_declare_ref_del(env, dto, th);
                if (rc)
                        return rc;

                rc = lod_sub_declare_delete(env, dto,
                                        (const struct dt_key *)dotdot, th);
                if (rc)
                        return rc;

                snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
                         PFID(lu_object_fid(&dto->do_lu)), i);

                rc = lod_sub_declare_delete(env, next,
                                        (const struct dt_key *)stripe_name, th);
                if (rc)
                        return rc;

                rc = lod_sub_declare_ref_del(env, next, th);
                if (rc)
                        return rc;
        }

        return 0;
}

/*
 * delete stripes from dir master object, the lum_stripe_count in argument is
 * the final stripe count, the stripes after that will be deleted, NB, they
 * are not destroyed, but deleted from it's parent namespace, this function
 * will be called in two places:
 * 1. mdd_migrate_create() delete stripes from source, and append them to
 *    target.
 * 2. mdd_dir_layout_shrink() delete stripes from source, and destroy them.
 */
static int lod_dir_layout_delete(const struct lu_env *env,
                                 struct dt_object *dt,
                                 const struct lu_buf *buf,
                                 struct thandle *th)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_object *lo = lod_dt_obj(dt);
        struct dt_object *next = dt_object_child(dt);
        struct lmv_user_md *lmu = buf->lb_buf;
        __u32 final_stripe_count;
        char *stripe_name = info->lti_key;
        struct dt_object *dto;
        int i;
        int rc = 0;

        ENTRY;

        if (!lmu)
                RETURN(-EINVAL);

        final_stripe_count = le32_to_cpu(lmu->lum_stripe_count);
        if (final_stripe_count >= lo->ldo_dir_stripe_count)
                RETURN(-EINVAL);

        for (i = final_stripe_count; i < lo->ldo_dir_stripe_count; i++) {
                dto = lo->ldo_stripe[i];
                if (!dto)
                        continue;

                rc = lod_sub_delete(env, dto,
                                    (const struct dt_key *)dotdot, th);
                if (rc)
                        break;

                snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
                         PFID(lu_object_fid(&dto->do_lu)), i);

                rc = lod_sub_delete(env, next,
                                    (const struct dt_key *)stripe_name, th);
                if (rc)
                        break;

                rc = lod_sub_ref_del(env, next, th);
                if (rc)
                        break;
        }

        lod_striping_free(env, lod_dt_obj(dt));

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_declare_xattr_set.
 *
 * Used with regular (non-striped) objects. Basically it
 * initializes the striping information and applies the
 * change to all the stripes.
 *
 * \see dt_object_operations::do_declare_xattr_set() in the API description
 * for details.
 */
static int lod_dir_declare_xattr_set(const struct lu_env *env,
                                     struct dt_object *dt,
                                     const struct lu_buf *buf,
                                     const char *name, int fl,
                                     struct thandle *th)
{
        struct dt_object        *next = dt_object_child(dt);
        struct lod_device       *d = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_object       *lo = lod_dt_obj(dt);
        int                     i;
        int                     rc;
        ENTRY;

        if (strcmp(name, XATTR_NAME_DEFAULT_LMV) == 0) {
                struct lmv_user_md_v1 *lum;

                LASSERT(buf != NULL && buf->lb_buf != NULL);
                lum = buf->lb_buf;
                rc = lod_verify_md_striping(d, lum);
                if (rc != 0)
                        RETURN(rc);
        } else if (strcmp(name, XATTR_NAME_LOV) == 0) {
                rc = lod_verify_striping(d, lo, buf, false);
                if (rc != 0)
                        RETURN(rc);
        }

        rc = lod_sub_declare_xattr_set(env, next, buf, name, fl, th);
        if (rc != 0)
                RETURN(rc);

        /* Note: Do not set LinkEA on sub-stripes, otherwise
         * it will confuse the fid2path process(see mdt_path_current()).
         * The linkEA between master and sub-stripes is set in
         * lod_xattr_set_lmv(). */
        if (strcmp(name, XATTR_NAME_LINK) == 0)
                RETURN(0);

        /* set xattr to each stripes, if needed */
        rc = lod_striping_load(env, lo);
        if (rc != 0)
                RETURN(rc);

        if (lo->ldo_dir_stripe_count == 0)
                RETURN(0);

        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                if (!lo->ldo_stripe[i])
                        continue;

                if (!dt_object_exists(lo->ldo_stripe[i]))
                        continue;

                rc = lod_sub_declare_xattr_set(env, lo->ldo_stripe[i],
                                               buf, name, fl, th);
                if (rc != 0)
                        break;
        }

        RETURN(rc);
}

static int
lod_obj_stripe_replace_parent_fid_cb(const struct lu_env *env,
                                     struct lod_object *lo,
                                     struct dt_object *dt, struct thandle *th,
                                     int comp_idx, int stripe_idx,
                                     struct lod_obj_stripe_cb_data *data)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_layout_component *comp = &lo->ldo_comp_entries[comp_idx];
        struct filter_fid *ff = &info->lti_ff;
        struct lu_buf *buf = &info->lti_buf;
        int rc;

        buf->lb_buf = ff;
        buf->lb_len = sizeof(*ff);
        rc = dt_xattr_get(env, dt, buf, XATTR_NAME_FID);
        if (rc < 0) {
                if (rc == -ENODATA)
                        return 0;
                return rc;
        }

        /*
         * locd_buf is set if it's called by dir migration, which doesn't check
         * pfid and comp id.
         */
        if (data->locd_buf) {
                memset(ff, 0, sizeof(*ff));
                ff->ff_parent = *(struct lu_fid *)data->locd_buf->lb_buf;
        } else {
                filter_fid_le_to_cpu(ff, ff, sizeof(*ff));

                if (lu_fid_eq(lod_object_fid(lo), &ff->ff_parent) &&
                    ff->ff_layout.ol_comp_id == comp->llc_id)
                        return 0;

                memset(ff, 0, sizeof(*ff));
                ff->ff_parent = *lu_object_fid(&lo->ldo_obj.do_lu);
        }

        /* rewrite filter_fid */
        ff->ff_parent.f_ver = stripe_idx;
        ff->ff_layout.ol_stripe_size = comp->llc_stripe_size;
        ff->ff_layout.ol_stripe_count = comp->llc_stripe_count;
        ff->ff_layout.ol_comp_id = comp->llc_id;
        ff->ff_layout.ol_comp_start = comp->llc_extent.e_start;
        ff->ff_layout.ol_comp_end = comp->llc_extent.e_end;
        filter_fid_cpu_to_le(ff, ff, sizeof(*ff));

        if (data->locd_declare)
                rc = lod_sub_declare_xattr_set(env, dt, buf, XATTR_NAME_FID,
                                               LU_XATTR_REPLACE, th);
        else
                rc = lod_sub_xattr_set(env, dt, buf, XATTR_NAME_FID,
                                       LU_XATTR_REPLACE, th);

        return rc;
}

/**
 * Reset parent FID on OST object
 *
 * Replace parent FID with @dt object FID, which is only called during migration
 * to reset the parent FID after the MDT object is migrated to the new MDT, i.e.
 * the FID is changed.
 *
 * \param[in] env execution environment
 * \param[in] dt dt_object whose stripes's parent FID will be reset
 * \parem[in] th thandle
 * \param[in] declare if it is declare
 *
 * \retval      0 if reset succeeds
 * \retval      negative errno if reset fails
 */
static int lod_replace_parent_fid(const struct lu_env *env,
                                  struct dt_object *dt,
                                  const struct lu_buf *buf,
                                  struct thandle *th, bool declare)
{
        struct lod_object *lo = lod_dt_obj(dt);
        struct lod_thread_info  *info = lod_env_info(env);
        struct filter_fid *ff;
        struct lod_obj_stripe_cb_data data = { { 0 } };
        int rc;
        ENTRY;

        LASSERT(S_ISREG(dt->do_lu.lo_header->loh_attr));

        /* set xattr to each stripes, if needed */
        rc = lod_striping_load(env, lo);
        if (rc != 0)
                RETURN(rc);

        if (!lod_obj_is_striped(dt))
                RETURN(0);

        if (info->lti_ea_store_size < sizeof(*ff)) {
                rc = lod_ea_store_resize(info, sizeof(*ff));
                if (rc != 0)
                        RETURN(rc);
        }

        data.locd_declare = declare;
        data.locd_stripe_cb = lod_obj_stripe_replace_parent_fid_cb;
        data.locd_buf = buf;
        rc = lod_obj_for_each_stripe(env, lo, th, &data);

        RETURN(rc);
}

inline __u16 lod_comp_entry_stripe_count(struct lod_object *lo,
                                         struct lod_layout_component *entry,
                                         bool is_dir)
{
        struct lod_device *lod = lu2lod_dev(lod2lu_obj(lo)->lo_dev);

        if (is_dir)
                return  0;
        else if (lod_comp_inited(entry))
                return entry->llc_stripe_count;
        else if ((__u16)-1 == entry->llc_stripe_count)
                return lod->lod_desc.ld_tgt_count;
        else
                return lod_get_stripe_count(lod, lo,
                                            entry->llc_stripe_count, false);
}

static int lod_comp_md_size(struct lod_object *lo, bool is_dir)
{
        int magic, size = 0, i;
        struct lod_layout_component *comp_entries;
        __u16 comp_cnt;
        bool is_composite, is_foreign = false;

        if (is_dir) {
                comp_cnt = lo->ldo_def_striping->lds_def_comp_cnt;
                comp_entries = lo->ldo_def_striping->lds_def_comp_entries;
                is_composite =
                        lo->ldo_def_striping->lds_def_striping_is_composite;
        } else {
                comp_cnt = lo->ldo_comp_cnt;
                comp_entries = lo->ldo_comp_entries;
                is_composite = lo->ldo_is_composite;
                is_foreign = lo->ldo_is_foreign;
        }

        if (is_foreign)
                return lo->ldo_foreign_lov_size;

        LASSERT(comp_cnt != 0 && comp_entries != NULL);
        if (is_composite) {
                size = sizeof(struct lov_comp_md_v1) +
                       sizeof(struct lov_comp_md_entry_v1) * comp_cnt;
                LASSERT(size % sizeof(__u64) == 0);
        }

        for (i = 0; i < comp_cnt; i++) {
                __u16 stripe_count;

                magic = comp_entries[i].llc_pool ? LOV_MAGIC_V3 : LOV_MAGIC_V1;
                stripe_count = lod_comp_entry_stripe_count(lo, &comp_entries[i],
                                                           is_dir);
                if (!is_dir && is_composite)
                        lod_comp_shrink_stripe_count(&comp_entries[i],
                                                     &stripe_count);

                size += lov_user_md_size(stripe_count, magic);
                LASSERT(size % sizeof(__u64) == 0);
        }
        return size;
}

/**
 * Declare component add. The xattr name is XATTR_LUSTRE_LOV.add, and
 * the xattr value is binary lov_comp_md_v1 which contains component(s)
 * to be added.
  *
 * \param[in] env       execution environment
 * \param[in] dt        dt_object to add components on
 * \param[in] buf       buffer contains components to be added
 * \parem[in] th        thandle
 *
 * \retval      0 on success
 * \retval      negative errno on failure
 */
static int lod_declare_layout_add(const struct lu_env *env,
                                  struct dt_object *dt,
                                  const struct lu_buf *buf,
                                  struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_layout_component *comp_array, *lod_comp, *old_array;
        struct lod_device       *d = lu2lod_dev(dt->do_lu.lo_dev);
        struct dt_object *next = dt_object_child(dt);
        struct lov_desc         *desc = &d->lod_desc;
        struct lod_object       *lo = lod_dt_obj(dt);
        struct lov_user_md_v3   *v3;
        struct lov_comp_md_v1   *comp_v1 = buf->lb_buf;
        __u32   magic;
        int     i, rc, array_cnt, old_array_cnt;
        ENTRY;

        LASSERT(lo->ldo_is_composite);

        if (lo->ldo_flr_state != LCM_FL_NONE)
                RETURN(-EBUSY);

        rc = lod_verify_striping(d, lo, buf, false);
        if (rc != 0)
                RETURN(rc);

        magic = comp_v1->lcm_magic;
        if (magic == __swab32(LOV_USER_MAGIC_COMP_V1)) {
                lustre_swab_lov_comp_md_v1(comp_v1);
                magic = comp_v1->lcm_magic;
        }

        if (magic != LOV_USER_MAGIC_COMP_V1)
                RETURN(-EINVAL);

        array_cnt = lo->ldo_comp_cnt + comp_v1->lcm_entry_count;
        OBD_ALLOC(comp_array, sizeof(*comp_array) * array_cnt);
        if (comp_array == NULL)
                RETURN(-ENOMEM);

        memcpy(comp_array, lo->ldo_comp_entries,
               sizeof(*comp_array) * lo->ldo_comp_cnt);

        for (i = 0; i < comp_v1->lcm_entry_count; i++) {
                struct lov_user_md_v1 *v1;
                struct lu_extent *ext;

                v1 = (struct lov_user_md *)((char *)comp_v1 +
                                comp_v1->lcm_entries[i].lcme_offset);
                ext = &comp_v1->lcm_entries[i].lcme_extent;

                lod_comp = &comp_array[lo->ldo_comp_cnt + i];
                lod_comp->llc_extent.e_start = ext->e_start;
                lod_comp->llc_extent.e_end = ext->e_end;
                lod_comp->llc_stripe_offset = v1->lmm_stripe_offset;
                lod_comp->llc_flags = comp_v1->lcm_entries[i].lcme_flags;

                lod_comp->llc_stripe_count = v1->lmm_stripe_count;
                lod_comp->llc_stripe_size = v1->lmm_stripe_size;
                lod_adjust_stripe_info(lod_comp, desc);

                if (v1->lmm_magic == LOV_USER_MAGIC_V3) {
                        v3 = (struct lov_user_md_v3 *) v1;
                        if (v3->lmm_pool_name[0] != '\0') {
                                rc = lod_set_pool(&lod_comp->llc_pool,
                                                  v3->lmm_pool_name);
                                if (rc)
                                        GOTO(error, rc);
                        }
                }
        }

        old_array = lo->ldo_comp_entries;
        old_array_cnt = lo->ldo_comp_cnt;

        lo->ldo_comp_entries = comp_array;
        lo->ldo_comp_cnt = array_cnt;

        /* No need to increase layout generation here, it will be increased
         * later when generating component ID for the new components */

        info->lti_buf.lb_len = lod_comp_md_size(lo, false);
        rc = lod_sub_declare_xattr_set(env, next, &info->lti_buf,
                                              XATTR_NAME_LOV, 0, th);
        if (rc) {
                lo->ldo_comp_entries = old_array;
                lo->ldo_comp_cnt = old_array_cnt;
                GOTO(error, rc);
        }

        OBD_FREE(old_array, sizeof(*lod_comp) * old_array_cnt);

        LASSERT(lo->ldo_mirror_count == 1);
        lo->ldo_mirrors[0].lme_end = array_cnt - 1;

        RETURN(0);

error:
        for (i = lo->ldo_comp_cnt; i < array_cnt; i++) {
                lod_comp = &comp_array[i];
                if (lod_comp->llc_pool != NULL) {
                        OBD_FREE(lod_comp->llc_pool,
                                 strlen(lod_comp->llc_pool) + 1);
                        lod_comp->llc_pool = NULL;
                }
        }
        OBD_FREE(comp_array, sizeof(*comp_array) * array_cnt);
        RETURN(rc);
}

/**
 * Declare component set. The xattr is name XATTR_LUSTRE_LOV.set.$field,
 * the '$field' can only be 'flags' now. The xattr value is binary
 * lov_comp_md_v1 which contains the component ID(s) and the value of
 * the field to be modified.
 *
 * \param[in] env       execution environment
 * \param[in] dt        dt_object to be modified
 * \param[in] op        operation string, like "set.flags"
 * \param[in] buf       buffer contains components to be set
 * \parem[in] th        thandle
 *
 * \retval      0 on success
 * \retval      negative errno on failure
 */
static int lod_declare_layout_set(const struct lu_env *env,
                                  struct dt_object *dt,
                                  char *op, const struct lu_buf *buf,
                                  struct thandle *th)
{
        struct lod_layout_component     *lod_comp;
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_device       *d = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_object       *lo = lod_dt_obj(dt);
        struct lov_comp_md_v1   *comp_v1 = buf->lb_buf;
        __u32   magic;
        int     i, j, rc;
        bool    changed = false;
        ENTRY;

        if (strcmp(op, "set.flags") != 0) {
                CDEBUG(D_LAYOUT, "%s: operation (%s) not supported.\n",
                       lod2obd(d)->obd_name, op);
                RETURN(-ENOTSUPP);
        }

        magic = comp_v1->lcm_magic;
        if (magic == __swab32(LOV_USER_MAGIC_COMP_V1)) {
                lustre_swab_lov_comp_md_v1(comp_v1);
                magic = comp_v1->lcm_magic;
        }

        if (magic != LOV_USER_MAGIC_COMP_V1)
                RETURN(-EINVAL);

        if (comp_v1->lcm_entry_count == 0) {
                CDEBUG(D_LAYOUT, "%s: entry count is zero.\n",
                       lod2obd(d)->obd_name);
                RETURN(-EINVAL);
        }

        for (i = 0; i < comp_v1->lcm_entry_count; i++) {
                __u32 id = comp_v1->lcm_entries[i].lcme_id;
                __u32 flags = comp_v1->lcm_entries[i].lcme_flags;
                __u32 mirror_flag = flags & LCME_MIRROR_FLAGS;
                bool neg = flags & LCME_FL_NEG;

                if (flags & LCME_FL_INIT) {
                        if (changed)
                                lod_striping_free(env, lo);
                        RETURN(-EINVAL);
                }

                flags &= ~(LCME_MIRROR_FLAGS | LCME_FL_NEG);
                for (j = 0; j < lo->ldo_comp_cnt; j++) {
                        lod_comp = &lo->ldo_comp_entries[j];

                        /* lfs only put one flag in each entry */
                        if ((flags && id != lod_comp->llc_id) ||
                            (mirror_flag && mirror_id_of(id) !=
                                            mirror_id_of(lod_comp->llc_id)))
                                continue;

                        if (neg) {
                                if (flags)
                                        lod_comp->llc_flags &= ~flags;
                                if (mirror_flag)
                                        lod_comp->llc_flags &= ~mirror_flag;
                        } else {
                                if (flags)
                                        lod_comp->llc_flags |= flags;
                                if (mirror_flag) {
                                        lod_comp->llc_flags |= mirror_flag;
                                        if (mirror_flag & LCME_FL_NOSYNC)
                                                lod_comp->llc_timestamp =
                                                       ktime_get_real_seconds();
                                }
                        }
                        changed = true;
                }
        }

        if (!changed) {
                CDEBUG(D_LAYOUT, "%s: requested component(s) not found.\n",
                       lod2obd(d)->obd_name);
                RETURN(-EINVAL);
        }

        lod_obj_inc_layout_gen(lo);

        info->lti_buf.lb_len = lod_comp_md_size(lo, false);
        rc = lod_sub_declare_xattr_set(env, dt_object_child(dt), &info->lti_buf,
                                       XATTR_NAME_LOV, LU_XATTR_REPLACE, th);
        RETURN(rc);
}

/**
 * Declare component deletion. The xattr name is XATTR_LUSTRE_LOV.del,
 * and the xattr value is a unique component ID or a special lcme_id.
 *
 * \param[in] env       execution environment
 * \param[in] dt        dt_object to be operated on
 * \param[in] buf       buffer contains component ID or lcme_id
 * \parem[in] th        thandle
 *
 * \retval      0 on success
 * \retval      negative errno on failure
 */
static int lod_declare_layout_del(const struct lu_env *env,
                                  struct dt_object *dt,
                                  const struct lu_buf *buf,
                                  struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct dt_object *next = dt_object_child(dt);
        struct lod_device *d = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_object *lo = lod_dt_obj(dt);
        struct lu_attr *attr = &lod_env_info(env)->lti_attr;
        struct lov_comp_md_v1 *comp_v1 = buf->lb_buf;
        __u32 magic, id, flags, neg_flags = 0;
        int rc, i, j, left;
        ENTRY;

        LASSERT(lo->ldo_is_composite);

        if (lo->ldo_flr_state != LCM_FL_NONE)
                RETURN(-EBUSY);

        magic = comp_v1->lcm_magic;
        if (magic == __swab32(LOV_USER_MAGIC_COMP_V1)) {
                lustre_swab_lov_comp_md_v1(comp_v1);
                magic = comp_v1->lcm_magic;
        }

        if (magic != LOV_USER_MAGIC_COMP_V1)
                RETURN(-EINVAL);

        id = comp_v1->lcm_entries[0].lcme_id;
        flags = comp_v1->lcm_entries[0].lcme_flags;

        if (id > LCME_ID_MAX || (flags & ~LCME_KNOWN_FLAGS)) {
                CDEBUG(D_LAYOUT, "%s: invalid component id %#x, flags %#x\n",
                       lod2obd(d)->obd_name, id, flags);
                RETURN(-EINVAL);
        }

        if (id != LCME_ID_INVAL && flags != 0) {
                CDEBUG(D_LAYOUT, "%s: specified both id and flags.\n",
                       lod2obd(d)->obd_name);
                RETURN(-EINVAL);
        }

        if (id == LCME_ID_INVAL && !flags) {
                CDEBUG(D_LAYOUT, "%s: no id or flags specified.\n",
                       lod2obd(d)->obd_name);
                RETURN(-EINVAL);
        }

        if (flags & LCME_FL_NEG) {
                neg_flags = flags & ~LCME_FL_NEG;
                flags = 0;
        }

        left = lo->ldo_comp_cnt;
        if (left <= 0)
                RETURN(-EINVAL);

        for (i = (lo->ldo_comp_cnt - 1); i >= 0; i--) {
                struct lod_layout_component *lod_comp;

                lod_comp = &lo->ldo_comp_entries[i];

                if (id != LCME_ID_INVAL && id != lod_comp->llc_id)
                        continue;
                else if (flags && !(flags & lod_comp->llc_flags))
                        continue;
                else if (neg_flags && (neg_flags & lod_comp->llc_flags))
                        continue;

                if (left != (i + 1)) {
                        CDEBUG(D_LAYOUT, "%s: this deletion will create "
                               "a hole.\n", lod2obd(d)->obd_name);
                        RETURN(-EINVAL);
                }
                left--;

                /* Mark the component as deleted */
                lod_comp->llc_id = LCME_ID_INVAL;

                /* Not instantiated component */
                if (lod_comp->llc_stripe == NULL)
                        continue;

                LASSERT(lod_comp->llc_stripe_count > 0);
                for (j = 0; j < lod_comp->llc_stripe_count; j++) {
                        struct dt_object *obj = lod_comp->llc_stripe[j];

                        if (obj == NULL)
                                continue;
                        rc = lod_sub_declare_destroy(env, obj, th);
                        if (rc)
                                RETURN(rc);
                }
        }

        LASSERTF(left >= 0, "left = %d\n", left);
        if (left == lo->ldo_comp_cnt) {
                CDEBUG(D_LAYOUT, "%s: requested component id:%#x not found\n",
                       lod2obd(d)->obd_name, id);
                RETURN(-EINVAL);
        }

        memset(attr, 0, sizeof(*attr));
        attr->la_valid = LA_SIZE;
        rc = lod_sub_declare_attr_set(env, next, attr, th);
        if (rc)
                RETURN(rc);

        if (left > 0) {
                info->lti_buf.lb_len = lod_comp_md_size(lo, false);
                rc = lod_sub_declare_xattr_set(env, next, &info->lti_buf,
                                               XATTR_NAME_LOV, 0, th);
        } else {
                rc = lod_sub_declare_xattr_del(env, next, XATTR_NAME_LOV, th);
        }

        RETURN(rc);
}

/**
 * Declare layout add/set/del operations issued by special xattr names:
 *
 * XATTR_LUSTRE_LOV.add         add component(s) to existing file
 * XATTR_LUSTRE_LOV.del         delete component(s) from existing file
 * XATTR_LUSTRE_LOV.set.$field  set specified field of certain component(s)
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] name      name of xattr
 * \param[in] buf       lu_buf contains xattr value
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_declare_modify_layout(const struct lu_env *env,
                                     struct dt_object *dt,
                                     const char *name,
                                     const struct lu_buf *buf,
                                     struct thandle *th)
{
        struct lod_device *d = lu2lod_dev(dt->do_lu.lo_dev);
        struct lod_object *lo = lod_dt_obj(dt);
        char *op;
        int rc, len = strlen(XATTR_LUSTRE_LOV);
        ENTRY;

        LASSERT(dt_object_exists(dt));

        if (strlen(name) <= len || name[len] != '.') {
                CDEBUG(D_LAYOUT, "%s: invalid xattr name: %s\n",
                       lod2obd(d)->obd_name, name);
                RETURN(-EINVAL);
        }
        len++;

        rc = lod_striping_load(env, lo);
        if (rc)
                GOTO(unlock, rc);

        /* the layout to be modified must be a composite layout */
        if (!lo->ldo_is_composite) {
                CDEBUG(D_LAYOUT, "%s: object "DFID" isn't a composite file.\n",
                       lod2obd(d)->obd_name, PFID(lu_object_fid(&dt->do_lu)));
                GOTO(unlock, rc = -EINVAL);
        }

        op = (char *)name + len;
        if (strcmp(op, "add") == 0) {
                rc = lod_declare_layout_add(env, dt, buf, th);
        } else if (strcmp(op, "del") == 0) {
                rc = lod_declare_layout_del(env, dt, buf, th);
        } else if (strncmp(op, "set", strlen("set")) == 0) {
                rc = lod_declare_layout_set(env, dt, op, buf, th);
        } else  {
                CDEBUG(D_LAYOUT, "%s: unsupported xattr name:%s\n",
                       lod2obd(d)->obd_name, name);
                GOTO(unlock, rc = -ENOTSUPP);
        }
unlock:
        if (rc)
                lod_striping_free(env, lo);

        RETURN(rc);
}

/**
 * Convert a plain file lov_mds_md to a composite layout.
 *
 * \param[in,out] info  the thread info::lti_ea_store buffer contains little
 *                      endian plain file layout
 *
 * \retval              0 on success, <0 on failure
 */
static int lod_layout_convert(struct lod_thread_info *info)
{
        struct lov_mds_md *lmm = info->lti_ea_store;
        struct lov_mds_md *lmm_save;
        struct lov_comp_md_v1 *lcm;
        struct lov_comp_md_entry_v1 *lcme;
        size_t size;
        __u32 blob_size;
        int rc = 0;
        ENTRY;

        /* realloc buffer to a composite layout which contains one component */
        blob_size = lov_mds_md_size(le16_to_cpu(lmm->lmm_stripe_count),
                                    le32_to_cpu(lmm->lmm_magic));
        size = sizeof(*lcm) + sizeof(*lcme) + blob_size;

        OBD_ALLOC_LARGE(lmm_save, blob_size);
        if (!lmm_save)
                GOTO(out, rc = -ENOMEM);

        memcpy(lmm_save, lmm, blob_size);

        if (info->lti_ea_store_size < size) {
                rc = lod_ea_store_resize(info, size);
                if (rc)
                        GOTO(out, rc);
        }

        lcm = info->lti_ea_store;
        lcm->lcm_magic = cpu_to_le32(LOV_MAGIC_COMP_V1);
        lcm->lcm_size = cpu_to_le32(size);
        lcm->lcm_layout_gen = cpu_to_le32(le16_to_cpu(
                                                lmm_save->lmm_layout_gen));
        lcm->lcm_flags = cpu_to_le16(LCM_FL_NONE);
        lcm->lcm_entry_count = cpu_to_le16(1);
        lcm->lcm_mirror_count = 0;

        lcme = &lcm->lcm_entries[0];
        lcme->lcme_flags = cpu_to_le32(LCME_FL_INIT);
        lcme->lcme_extent.e_start = 0;
        lcme->lcme_extent.e_end = cpu_to_le64(OBD_OBJECT_EOF);
        lcme->lcme_offset = cpu_to_le32(sizeof(*lcm) + sizeof(*lcme));
        lcme->lcme_size = cpu_to_le32(blob_size);

        memcpy((char *)lcm + lcme->lcme_offset, (char *)lmm_save, blob_size);

        EXIT;
out:
        if (lmm_save)
                OBD_FREE_LARGE(lmm_save, blob_size);
        return rc;
}

/**
 * Merge layouts to form a mirrored file.
 */
static int lod_declare_layout_merge(const struct lu_env *env,
                struct dt_object *dt, const struct lu_buf *mbuf,
                struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct lu_buf           *buf = &info->lti_buf;
        struct lod_object       *lo = lod_dt_obj(dt);
        struct lov_comp_md_v1   *lcm;
        struct lov_comp_md_v1   *cur_lcm;
        struct lov_comp_md_v1   *merge_lcm;
        struct lov_comp_md_entry_v1     *lcme;
        size_t size = 0;
        size_t offset;
        __u16 cur_entry_count;
        __u16 merge_entry_count;
        __u32 id = 0;
        __u16 mirror_id = 0;
        __u32 mirror_count;
        int     rc, i;
        ENTRY;

        merge_lcm = mbuf->lb_buf;
        if (mbuf->lb_len < sizeof(*merge_lcm))
                RETURN(-EINVAL);

        /* must be an existing layout from disk */
        if (le32_to_cpu(merge_lcm->lcm_magic) != LOV_MAGIC_COMP_V1)
                RETURN(-EINVAL);

        merge_entry_count = le16_to_cpu(merge_lcm->lcm_entry_count);

        /* do not allow to merge two mirrored files */
        if (le16_to_cpu(merge_lcm->lcm_mirror_count))
                RETURN(-EBUSY);

        /* verify the target buffer */
        rc = lod_get_lov_ea(env, lo);
        if (rc <= 0)
                RETURN(rc ? : -ENODATA);

        cur_lcm = info->lti_ea_store;
        switch (le32_to_cpu(cur_lcm->lcm_magic)) {
        case LOV_MAGIC_V1:
        case LOV_MAGIC_V3:
                rc = lod_layout_convert(info);
                break;
        case LOV_MAGIC_COMP_V1:
        case LOV_MAGIC_SEL:
                rc = 0;
                break;
        default:
                rc = -EINVAL;
        }
        if (rc)
                RETURN(rc);

        /* info->lti_ea_store could be reallocated in lod_layout_convert() */
        cur_lcm = info->lti_ea_store;
        cur_entry_count = le16_to_cpu(cur_lcm->lcm_entry_count);

        /* 'lcm_mirror_count + 1' is the current # of mirrors the file has */
        mirror_count = le16_to_cpu(cur_lcm->lcm_mirror_count) + 1;
        if (mirror_count + 1 > LUSTRE_MIRROR_COUNT_MAX)
                RETURN(-ERANGE);

        /* size of new layout */
        size = le32_to_cpu(cur_lcm->lcm_size) +
               le32_to_cpu(merge_lcm->lcm_size) - sizeof(*cur_lcm);

        memset(buf, 0, sizeof(*buf));
        lu_buf_alloc(buf, size);
        if (buf->lb_buf == NULL)
                RETURN(-ENOMEM);

        lcm = buf->lb_buf;
        memcpy(lcm, cur_lcm, sizeof(*lcm) + cur_entry_count * sizeof(*lcme));

        offset = sizeof(*lcm) +
                 sizeof(*lcme) * (cur_entry_count + merge_entry_count);
        for (i = 0; i < cur_entry_count; i++) {
                struct lov_comp_md_entry_v1 *cur_lcme;

                lcme = &lcm->lcm_entries[i];
                cur_lcme = &cur_lcm->lcm_entries[i];

                lcme->lcme_offset = cpu_to_le32(offset);
                memcpy((char *)lcm + offset,
                       (char *)cur_lcm + le32_to_cpu(cur_lcme->lcme_offset),
                       le32_to_cpu(lcme->lcme_size));

                offset += le32_to_cpu(lcme->lcme_size);

                if (mirror_count == 1 &&
                    mirror_id_of(le32_to_cpu(lcme->lcme_id)) == 0) {
                        /* Add mirror from a non-flr file, create new mirror ID.
                         * Otherwise, keep existing mirror's component ID, used
                         * for mirror extension.
                         */
                        id = pflr_id(1, i + 1);
                        lcme->lcme_id = cpu_to_le32(id);
                }

                id = MAX(le32_to_cpu(lcme->lcme_id), id);
        }

        mirror_id = mirror_id_of(id) + 1;
        for (i = 0; i < merge_entry_count; i++) {
                struct lov_comp_md_entry_v1 *merge_lcme;

                merge_lcme = &merge_lcm->lcm_entries[i];
                lcme = &lcm->lcm_entries[cur_entry_count + i];

                *lcme = *merge_lcme;
                lcme->lcme_offset = cpu_to_le32(offset);

                id = pflr_id(mirror_id, i + 1);
                lcme->lcme_id = cpu_to_le32(id);

                memcpy((char *)lcm + offset,
                       (char *)merge_lcm + le32_to_cpu(merge_lcme->lcme_offset),
                       le32_to_cpu(lcme->lcme_size));

                offset += le32_to_cpu(lcme->lcme_size);
        }

        /* fixup layout information */
        lod_obj_inc_layout_gen(lo);
        lcm->lcm_layout_gen = cpu_to_le32(lo->ldo_layout_gen);
        lcm->lcm_size = cpu_to_le32(size);
        lcm->lcm_entry_count = cpu_to_le16(cur_entry_count + merge_entry_count);
        lcm->lcm_mirror_count = cpu_to_le16(mirror_count);
        if ((le16_to_cpu(lcm->lcm_flags) & LCM_FL_FLR_MASK) == LCM_FL_NONE)
                lcm->lcm_flags = cpu_to_le32(LCM_FL_RDONLY);

        rc = lod_striping_reload(env, lo, buf);
        if (rc)
                GOTO(out, rc);

        rc = lod_sub_declare_xattr_set(env, dt_object_child(dt), buf,
                                        XATTR_NAME_LOV, LU_XATTR_REPLACE, th);

out:
        lu_buf_free(buf);
        RETURN(rc);
}

/**
 * Split layouts, just set the LOVEA with the layout from mbuf.
 */
static int lod_declare_layout_split(const struct lu_env *env,
                struct dt_object *dt, const struct lu_buf *mbuf,
                struct thandle *th)
{
        struct lod_object *lo = lod_dt_obj(dt);
        struct lov_comp_md_v1 *lcm = mbuf->lb_buf;
        int rc;
        ENTRY;

        lod_obj_inc_layout_gen(lo);
        lcm->lcm_layout_gen = cpu_to_le32(lo->ldo_layout_gen);

        rc = lod_striping_reload(env, lo, mbuf);
        if (rc)
                RETURN(rc);

        rc = lod_sub_declare_xattr_set(env, dt_object_child(dt), mbuf,
                                       XATTR_NAME_LOV, LU_XATTR_REPLACE, th);
        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_declare_xattr_set.
 *
 * \see dt_object_operations::do_declare_xattr_set() in the API description
 * for details.
 *
 * the extension to the API:
 *   - declaring LOVEA requests striping creation
 *   - LU_XATTR_REPLACE means layout swap
 */
static int lod_declare_xattr_set(const struct lu_env *env,
                                 struct dt_object *dt,
                                 const struct lu_buf *buf,
                                 const char *name, int fl,
                                 struct thandle *th)
{
        struct dt_object *next = dt_object_child(dt);
        struct lu_attr   *attr = &lod_env_info(env)->lti_attr;
        __u32             mode;
        int               rc;
        ENTRY;

        mode = dt->do_lu.lo_header->loh_attr & S_IFMT;
        if ((S_ISREG(mode) || mode == 0) &&
            !(fl & (LU_XATTR_REPLACE | LU_XATTR_MERGE | LU_XATTR_SPLIT)) &&
            (strcmp(name, XATTR_NAME_LOV) == 0 ||
             strcmp(name, XATTR_LUSTRE_LOV) == 0)) {
                /*
                 * this is a request to create object's striping.
                 *
                 * allow to declare predefined striping on a new (!mode) object
                 * which is supposed to be replay of regular file creation
                 * (when LOV setting is declared)
                 *
                 * LU_XATTR_REPLACE is set to indicate a layout swap
                 */
                if (dt_object_exists(dt)) {
                        rc = dt_attr_get(env, next, attr);
                        if (rc)
                                RETURN(rc);
                } else {
                        memset(attr, 0, sizeof(*attr));
                        attr->la_valid = LA_TYPE | LA_MODE;
                        attr->la_mode = S_IFREG;
                }
                rc = lod_declare_striped_create(env, dt, attr, buf, th);
        } else if (fl & LU_XATTR_MERGE) {
                LASSERT(strcmp(name, XATTR_NAME_LOV) == 0 ||
                        strcmp(name, XATTR_LUSTRE_LOV) == 0);
                rc = lod_declare_layout_merge(env, dt, buf, th);
        } else if (fl & LU_XATTR_SPLIT) {
                LASSERT(strcmp(name, XATTR_NAME_LOV) == 0 ||
                        strcmp(name, XATTR_LUSTRE_LOV) == 0);
                rc = lod_declare_layout_split(env, dt, buf, th);
        } else if (S_ISREG(mode) &&
                   strlen(name) > strlen(XATTR_LUSTRE_LOV) + 1 &&
                   strncmp(name, XATTR_LUSTRE_LOV,
                           strlen(XATTR_LUSTRE_LOV)) == 0) {
                /*
                 * this is a request to modify object's striping.
                 * add/set/del component(s).
                 */
                if (!dt_object_exists(dt))
                        RETURN(-ENOENT);

                rc = lod_declare_modify_layout(env, dt, name, buf, th);
        } else if (strncmp(name, XATTR_NAME_LMV, strlen(XATTR_NAME_LMV)) == 0 &&
                   strlen(name) > strlen(XATTR_NAME_LMV) + 1) {
                const char *op = name + strlen(XATTR_NAME_LMV) + 1;

                rc = -ENOTSUPP;
                if (strcmp(op, "add") == 0)
                        rc = lod_dir_declare_layout_add(env, dt, buf, th);
                else if (strcmp(op, "del") == 0)
                        rc = lod_dir_declare_layout_delete(env, dt, buf, th);
                else if (strcmp(op, "set") == 0)
                        rc = lod_sub_declare_xattr_set(env, next, buf,
                                                       XATTR_NAME_LMV, fl, th);

                RETURN(rc);
        } else if (S_ISDIR(mode)) {
                rc = lod_dir_declare_xattr_set(env, dt, buf, name, fl, th);
        } else if (strcmp(name, XATTR_NAME_FID) == 0) {
                rc = lod_replace_parent_fid(env, dt, buf, th, true);
        } else {
                rc = lod_sub_declare_xattr_set(env, next, buf, name, fl, th);
        }

        RETURN(rc);
}

/**
 * Apply xattr changes to the object.
 *
 * Applies xattr changes to the object and the stripes if the latter exist.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] buf       buffer pointing to the new value of xattr
 * \param[in] name      name of xattr
 * \param[in] fl        flags
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_xattr_set_internal(const struct lu_env *env,
                                  struct dt_object *dt,
                                  const struct lu_buf *buf,
                                  const char *name, int fl,
                                  struct thandle *th)
{
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
        int                     rc;
        int                     i;
        ENTRY;

        rc = lod_sub_xattr_set(env, next, buf, name, fl, th);
        if (rc != 0 || !S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(rc);

        /* Note: Do not set LinkEA on sub-stripes, otherwise
         * it will confuse the fid2path process(see mdt_path_current()).
         * The linkEA between master and sub-stripes is set in
         * lod_xattr_set_lmv(). */
        if (lo->ldo_dir_stripe_count == 0 || strcmp(name, XATTR_NAME_LINK) == 0)
                RETURN(0);

        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                if (!lo->ldo_stripe[i])
                        continue;

                if (!dt_object_exists(lo->ldo_stripe[i]))
                        continue;

                rc = lod_sub_xattr_set(env, lo->ldo_stripe[i], buf, name,
                                       fl, th);
                if (rc != 0)
                        break;
        }

        RETURN(rc);
}

/**
 * Delete an extended attribute.
 *
 * Deletes specified xattr from the object and the stripes if the latter exist.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] name      name of xattr
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_xattr_del_internal(const struct lu_env *env,
                                  struct dt_object *dt,
                                  const char *name, struct thandle *th)
{
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
        int                     rc;
        int                     i;
        ENTRY;

        rc = lod_sub_xattr_del(env, next, name, th);
        if (rc != 0 || !S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(rc);

        if (lo->ldo_dir_stripe_count == 0)
                RETURN(rc);

        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                LASSERT(lo->ldo_stripe[i]);

                rc = lod_sub_xattr_del(env, lo->ldo_stripe[i], name, th);
                if (rc != 0)
                        break;
        }

        RETURN(rc);
}

/**
 * Set default striping on a directory.
 *
 * Sets specified striping on a directory object unless it matches the default
 * striping (LOVEA_DELETE_VALUES() macro). In the latter case remove existing
 * EA. This striping will be used when regular file is being created in this
 * directory.
 *
 * \param[in] env       execution environment
 * \param[in] dt        the striped object
 * \param[in] buf       buffer with the striping
 * \param[in] name      name of EA
 * \param[in] fl        xattr flag (see OSD API description)
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_xattr_set_lov_on_dir(const struct lu_env *env,
                                    struct dt_object *dt,
                                    const struct lu_buf *buf,
                                    const char *name, int fl,
                                    struct thandle *th)
{
        struct lov_user_md_v1   *lum;
        struct lov_user_md_v3   *v3 = NULL;
        const char              *pool_name = NULL;
        int                      rc;
        bool                     is_del;
        ENTRY;

        LASSERT(buf != NULL && buf->lb_buf != NULL);
        lum = buf->lb_buf;

        switch (lum->lmm_magic) {
        case LOV_USER_MAGIC_SPECIFIC:
        case LOV_USER_MAGIC_V3:
                v3 = buf->lb_buf;
                if (v3->lmm_pool_name[0] != '\0')
                        pool_name = v3->lmm_pool_name;
                /* fall through */
        case LOV_USER_MAGIC_V1:
                /* if { size, offset, count } = { 0, -1, 0 } and no pool
                 * (i.e. all default values specified) then delete default
                 * striping from dir. */
                CDEBUG(D_LAYOUT,
                       "set default striping: sz %u # %u offset %d %s %s\n",
                       (unsigned)lum->lmm_stripe_size,
                       (unsigned)lum->lmm_stripe_count,
                       (int)lum->lmm_stripe_offset,
                       v3 ? "from" : "", v3 ? v3->lmm_pool_name : "");

                is_del = LOVEA_DELETE_VALUES(lum->lmm_stripe_size,
                                             lum->lmm_stripe_count,
                                             lum->lmm_stripe_offset,
                                             pool_name);
                break;
        case LOV_USER_MAGIC_COMP_V1:
        {
                struct lov_comp_md_v1 *lcm = (struct lov_comp_md_v1 *)lum;
                struct lov_comp_md_entry_v1 *lcme;
                int i, comp_cnt;

                comp_cnt = le16_to_cpu(lcm->lcm_entry_count);
                for (i = 0; i < comp_cnt; i++) {
                        lcme = &lcm->lcm_entries[i];
                        if (lcme->lcme_flags & cpu_to_le32(LCME_FL_EXTENSION)) {
                                lcm->lcm_magic = cpu_to_le32(LOV_MAGIC_SEL);
                                break;
                        }
                }

                is_del = false;
                break;
        }
        default:
                CERROR("Invalid magic %x\n", lum->lmm_magic);
                RETURN(-EINVAL);
        }

        if (is_del) {
                rc = lod_xattr_del_internal(env, dt, name, th);
                if (rc == -ENODATA)
                        rc = 0;
        } else {
                rc = lod_xattr_set_internal(env, dt, buf, name, fl, th);
        }

        RETURN(rc);
}

/**
 * Set default striping on a directory object.
 *
 * Sets specified striping on a directory object unless it matches the default
 * striping (LOVEA_DELETE_VALUES() macro). In the latter case remove existing
 * EA. This striping will be used when a new directory is being created in the
 * directory.
 *
 * \param[in] env       execution environment
 * \param[in] dt        the striped object
 * \param[in] buf       buffer with the striping
 * \param[in] name      name of EA
 * \param[in] fl        xattr flag (see OSD API description)
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_xattr_set_default_lmv_on_dir(const struct lu_env *env,
                                            struct dt_object *dt,
                                            const struct lu_buf *buf,
                                            const char *name, int fl,
                                            struct thandle *th)
{
        struct lmv_user_md_v1 *lum;
        int rc;

        ENTRY;

        LASSERT(buf != NULL && buf->lb_buf != NULL);
        lum = buf->lb_buf;

        CDEBUG(D_INFO,
               "set default stripe_count # %u stripe_offset %d hash %u\n",
              le32_to_cpu(lum->lum_stripe_count),
              (int)le32_to_cpu(lum->lum_stripe_offset),
              le32_to_cpu(lum->lum_hash_type));

        if (LMVEA_DELETE_VALUES((le32_to_cpu(lum->lum_stripe_count)),
                                 le32_to_cpu(lum->lum_stripe_offset)) &&
            le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC &&
            !(le32_to_cpu(lum->lum_hash_type) & LMV_HASH_FLAG_SPACE)) {
                rc = lod_xattr_del_internal(env, dt, name, th);
                if (rc == -ENODATA)
                        rc = 0;
        } else {
                rc = lod_xattr_set_internal(env, dt, buf, name, fl, th);
                if (rc != 0)
                        RETURN(rc);
        }

        RETURN(rc);
}

/**
 * Turn directory into a striped directory.
 *
 * During replay the client sends the striping created before MDT
 * failure, then the layer above LOD sends this defined striping
 * using ->do_xattr_set(), so LOD uses this method to replay creation
 * of the stripes. Notice the original information for the striping
 * (#stripes, FIDs, etc) was transferred in declare path.
 *
 * \param[in] env       execution environment
 * \param[in] dt        the striped object
 * \param[in] buf       not used currently
 * \param[in] name      not used currently
 * \param[in] fl        xattr flag (see OSD API description)
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_xattr_set_lmv(const struct lu_env *env, struct dt_object *dt,
                             const struct lu_buf *buf, const char *name,
                             int fl, struct thandle *th)
{
        struct lod_object       *lo = lod_dt_obj(dt);
        struct lod_thread_info  *info = lod_env_info(env);
        struct lu_attr          *attr = &info->lti_attr;
        struct dt_object_format *dof = &info->lti_format;
        struct lu_buf           lmv_buf;
        struct lu_buf           slave_lmv_buf;
        struct lmv_mds_md_v1    *lmm;
        struct lmv_mds_md_v1    *slave_lmm = NULL;
        struct dt_insert_rec    *rec = &info->lti_dt_rec;
        int                     i;
        int                     rc;
        ENTRY;

        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(-ENOTDIR);

        /* The stripes are supposed to be allocated in declare phase,
         * if there are no stripes being allocated, it will skip */
        if (lo->ldo_dir_stripe_count == 0) {
                if (lo->ldo_dir_is_foreign) {
                        rc = lod_sub_xattr_set(env, dt_object_child(dt), buf,
                                               XATTR_NAME_LMV, fl, th);
                        if (rc != 0)
                                RETURN(rc);
                }
                RETURN(0);
        }

        rc = dt_attr_get(env, dt_object_child(dt), attr);
        if (rc != 0)
                RETURN(rc);

        attr->la_valid = LA_ATIME | LA_MTIME | LA_CTIME |
                         LA_MODE | LA_UID | LA_GID | LA_TYPE | LA_PROJID;
        dof->dof_type = DFT_DIR;

        rc = lod_prep_lmv_md(env, dt, &lmv_buf);
        if (rc != 0)
                RETURN(rc);
        lmm = lmv_buf.lb_buf;

        OBD_ALLOC_PTR(slave_lmm);
        if (slave_lmm == NULL)
                RETURN(-ENOMEM);

        lod_prep_slave_lmv_md(slave_lmm, lmm);
        slave_lmv_buf.lb_buf = slave_lmm;
        slave_lmv_buf.lb_len = sizeof(*slave_lmm);

        rec->rec_type = S_IFDIR;
        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                struct dt_object *dto = lo->ldo_stripe[i];
                char *stripe_name = info->lti_key;
                struct lu_name *sname;
                struct linkea_data ldata = { NULL };
                struct lu_buf linkea_buf;

                /* OBD_FAIL_MDS_STRIPE_FID may leave stripe uninitialized */
                if (!dto)
                        continue;

                /* fail a remote stripe creation */
                if (i && OBD_FAIL_CHECK(OBD_FAIL_MDS_STRIPE_CREATE))
                        continue;

                /* if it's source stripe of migrating directory, don't create */
                if (!((lo->ldo_dir_hash_type & LMV_HASH_FLAG_MIGRATION) &&
                      i >= lo->ldo_dir_migrate_offset)) {
                        dt_write_lock(env, dto, MOR_TGT_CHILD);
                        rc = lod_sub_create(env, dto, attr, NULL, dof, th);
                        if (rc != 0) {
                                dt_write_unlock(env, dto);
                                GOTO(out, rc);
                        }

                        rc = lod_sub_ref_add(env, dto, th);
                        dt_write_unlock(env, dto);
                        if (rc != 0)
                                GOTO(out, rc);

                        rec->rec_fid = lu_object_fid(&dto->do_lu);
                        rc = lod_sub_insert(env, dto,
                                            (const struct dt_rec *)rec,
                                            (const struct dt_key *)dot, th);
                        if (rc != 0)
                                GOTO(out, rc);
                }

                rec->rec_fid = lu_object_fid(&dt->do_lu);
                rc = lod_sub_insert(env, dto, (struct dt_rec *)rec,
                                    (const struct dt_key *)dotdot, th);
                if (rc != 0)
                        GOTO(out, rc);

                if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_SLAVE_LMV) ||
                    cfs_fail_val != i) {
                        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_SLAVE_LMV) &&
                            cfs_fail_val == i)
                                slave_lmm->lmv_master_mdt_index =
                                                        cpu_to_le32(i + 1);
                        else
                                slave_lmm->lmv_master_mdt_index =
                                                        cpu_to_le32(i);

                        rc = lod_sub_xattr_set(env, dto, &slave_lmv_buf,
                                               XATTR_NAME_LMV, fl, th);
                        if (rc != 0)
                                GOTO(out, rc);
                }

                if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_BAD_SLAVE_NAME) &&
                    cfs_fail_val == i)
                        snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
                                 PFID(lu_object_fid(&dto->do_lu)), i + 1);
                else
                        snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
                                 PFID(lu_object_fid(&dto->do_lu)), i);

                sname = lod_name_get(env, stripe_name, strlen(stripe_name));
                rc = linkea_links_new(&ldata, &info->lti_linkea_buf,
                                      sname, lu_object_fid(&dt->do_lu));
                if (rc != 0)
                        GOTO(out, rc);

                linkea_buf.lb_buf = ldata.ld_buf->lb_buf;
                linkea_buf.lb_len = ldata.ld_leh->leh_len;
                rc = lod_sub_xattr_set(env, dto, &linkea_buf,
                                       XATTR_NAME_LINK, 0, th);
                if (rc != 0)
                        GOTO(out, rc);

                rec->rec_fid = lu_object_fid(&dto->do_lu);
                rc = lod_sub_insert(env, dt_object_child(dt),
                                    (const struct dt_rec *)rec,
                                    (const struct dt_key *)stripe_name, th);
                if (rc != 0)
                        GOTO(out, rc);

                rc = lod_sub_ref_add(env, dt_object_child(dt), th);
                if (rc != 0)
                        GOTO(out, rc);
        }

        if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_MASTER_LMV))
                rc = lod_sub_xattr_set(env, dt_object_child(dt),
                                       &lmv_buf, XATTR_NAME_LMV, fl, th);
out:
        if (slave_lmm != NULL)
                OBD_FREE_PTR(slave_lmm);

        RETURN(rc);
}

/**
 * Helper function to declare/execute creation of a striped directory
 *
 * Called in declare/create object path, prepare striping for a directory
 * and prepare defaults data striping for the objects to be created in
 * that directory. Notice the function calls "declaration" or "execution"
 * methods depending on \a declare param. This is a consequence of the
 * current approach while we don't have natural distributed transactions:
 * we basically execute non-local updates in the declare phase. So, the
 * arguments for the both phases are the same and this is the reason for
 * this function to exist.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] attr      attributes the stripes will be created with
 * \param[in] lmu       lmv_user_md if MDT indices are specified
 * \param[in] dof       format of stripes (see OSD API description)
 * \param[in] th        transaction handle
 * \param[in] declare   where to call "declare" or "execute" methods
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_dir_striping_create_internal(const struct lu_env *env,
                                            struct dt_object *dt,
                                            struct lu_attr *attr,
                                            const struct lu_buf *lmu,
                                            struct dt_object_format *dof,
                                            struct thandle *th,
                                            bool declare)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_object *lo = lod_dt_obj(dt);
        const struct lod_default_striping *lds = lo->ldo_def_striping;
        int rc;
        ENTRY;

        LASSERT(ergo(lds != NULL,
                     lds->lds_def_striping_set ||
                     lds->lds_dir_def_striping_set));

        if (!LMVEA_DELETE_VALUES(lo->ldo_dir_stripe_count,
                                 lo->ldo_dir_stripe_offset)) {
                if (!lmu) {
                        struct lmv_user_md_v1 *v1 = info->lti_ea_store;
                        int stripe_count = lo->ldo_dir_stripe_count;

                        if (info->lti_ea_store_size < sizeof(*v1)) {
                                rc = lod_ea_store_resize(info, sizeof(*v1));
                                if (rc != 0)
                                        RETURN(rc);
                                v1 = info->lti_ea_store;
                        }

                        memset(v1, 0, sizeof(*v1));
                        v1->lum_magic = cpu_to_le32(LMV_USER_MAGIC);
                        v1->lum_stripe_count = cpu_to_le32(stripe_count);
                        v1->lum_stripe_offset =
                                        cpu_to_le32(lo->ldo_dir_stripe_offset);

                        info->lti_buf.lb_buf = v1;
                        info->lti_buf.lb_len = sizeof(*v1);
                        lmu = &info->lti_buf;
                }

                if (declare)
                        rc = lod_declare_xattr_set_lmv(env, dt, attr, lmu, dof,
                                                       th);
                else
                        rc = lod_xattr_set_lmv(env, dt, lmu, XATTR_NAME_LMV, 0,
                                               th);
                if (rc != 0)
                        RETURN(rc);
        } else {
                /* foreign LMV EA case */
                if (lmu) {
                        struct lmv_foreign_md *lfm = lmu->lb_buf;

                        if (lfm->lfm_magic == LMV_MAGIC_FOREIGN) {
                                rc = lod_declare_xattr_set_lmv(env, dt, attr,
                                                               lmu, dof, th);
                        }
                } else {
                        if (lo->ldo_dir_is_foreign) {
                                LASSERT(lo->ldo_foreign_lmv != NULL &&
                                        lo->ldo_foreign_lmv_size > 0);
                                info->lti_buf.lb_buf = lo->ldo_foreign_lmv;
                                info->lti_buf.lb_len = lo->ldo_foreign_lmv_size;
                                lmu = &info->lti_buf;
                                rc = lod_xattr_set_lmv(env, dt, lmu,
                                                       XATTR_NAME_LMV, 0, th);
                        }
                }
        }

        /* Transfer default LMV striping from the parent */
        if (lds != NULL && lds->lds_dir_def_striping_set &&
            !(LMVEA_DELETE_VALUES(lds->lds_dir_def_stripe_count,
                                 lds->lds_dir_def_stripe_offset) &&
              le32_to_cpu(lds->lds_dir_def_hash_type) !=
              LMV_HASH_TYPE_UNKNOWN)) {
                struct lmv_user_md_v1 *v1 = info->lti_ea_store;

                if (info->lti_ea_store_size < sizeof(*v1)) {
                        rc = lod_ea_store_resize(info, sizeof(*v1));
                        if (rc != 0)
                                RETURN(rc);
                        v1 = info->lti_ea_store;
                }

                memset(v1, 0, sizeof(*v1));
                v1->lum_magic = cpu_to_le32(LMV_USER_MAGIC);
                v1->lum_stripe_count =
                        cpu_to_le32(lds->lds_dir_def_stripe_count);
                v1->lum_stripe_offset =
                        cpu_to_le32(lds->lds_dir_def_stripe_offset);
                v1->lum_hash_type =
                        cpu_to_le32(lds->lds_dir_def_hash_type);

                info->lti_buf.lb_buf = v1;
                info->lti_buf.lb_len = sizeof(*v1);
                if (declare)
                        rc = lod_dir_declare_xattr_set(env, dt, &info->lti_buf,
                                                       XATTR_NAME_DEFAULT_LMV,
                                                       0, th);
                else
                        rc = lod_xattr_set_default_lmv_on_dir(env, dt,
                                                  &info->lti_buf,
                                                  XATTR_NAME_DEFAULT_LMV, 0,
                                                  th);
                if (rc != 0)
                        RETURN(rc);
        }

        /* Transfer default LOV striping from the parent */
        if (lds != NULL && lds->lds_def_striping_set &&
            lds->lds_def_comp_cnt != 0) {
                struct lov_mds_md *lmm;
                int lmm_size = lod_comp_md_size(lo, true);

                if (info->lti_ea_store_size < lmm_size) {
                        rc = lod_ea_store_resize(info, lmm_size);
                        if (rc != 0)
                                RETURN(rc);
                }
                lmm = info->lti_ea_store;

                rc = lod_generate_lovea(env, lo, lmm, &lmm_size, true);
                if (rc != 0)
                        RETURN(rc);

                info->lti_buf.lb_buf = lmm;
                info->lti_buf.lb_len = lmm_size;

                if (declare)
                        rc = lod_dir_declare_xattr_set(env, dt, &info->lti_buf,
                                                       XATTR_NAME_LOV, 0, th);
                else
                        rc = lod_xattr_set_lov_on_dir(env, dt, &info->lti_buf,
                                                      XATTR_NAME_LOV, 0, th);
                if (rc != 0)
                        RETURN(rc);
        }

        RETURN(0);
}

static int lod_declare_dir_striping_create(const struct lu_env *env,
                                           struct dt_object *dt,
                                           struct lu_attr *attr,
                                           struct lu_buf *lmu,
                                           struct dt_object_format *dof,
                                           struct thandle *th)
{
        return lod_dir_striping_create_internal(env, dt, attr, lmu, dof, th,
                                                true);
}

static int lod_dir_striping_create(const struct lu_env *env,
                                   struct dt_object *dt,
                                   struct lu_attr *attr,
                                   struct dt_object_format *dof,
                                   struct thandle *th)
{
        return lod_dir_striping_create_internal(env, dt, attr, NULL, dof, th,
                                                false);
}

/**
 * Make LOV EA for striped object.
 *
 * Generate striping information and store it in the LOV EA of the given
 * object. The caller must ensure nobody else is calling the function
 * against the object concurrently. The transaction must be started.
 * FLDB service must be running as well; it's used to map FID to the target,
 * which is stored in LOV EA.
 *
 * \param[in] env               execution environment for this thread
 * \param[in] lo                LOD object
 * \param[in] th                transaction handle
 *
 * \retval                      0 if LOV EA is stored successfully
 * \retval                      negative error number on failure
 */
static int lod_generate_and_set_lovea(const struct lu_env *env,
                                      struct lod_object *lo,
                                      struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct dt_object        *next = dt_object_child(&lo->ldo_obj);
        struct lov_mds_md_v1    *lmm;
        int                      rc, lmm_size;
        ENTRY;

        LASSERT(lo);

        if (lo->ldo_comp_cnt == 0 && !lo->ldo_is_foreign) {
                lod_striping_free(env, lo);
                rc = lod_sub_xattr_del(env, next, XATTR_NAME_LOV, th);
                RETURN(rc);
        }

        lmm_size = lod_comp_md_size(lo, false);
        if (info->lti_ea_store_size < lmm_size) {
                rc = lod_ea_store_resize(info, lmm_size);
                if (rc)
                        RETURN(rc);
        }
        lmm = info->lti_ea_store;

        rc = lod_generate_lovea(env, lo, lmm, &lmm_size, false);
        if (rc)
                RETURN(rc);

        info->lti_buf.lb_buf = lmm;
        info->lti_buf.lb_len = lmm_size;
        rc = lod_sub_xattr_set(env, next, &info->lti_buf,
                               XATTR_NAME_LOV, 0, th);
        RETURN(rc);
}

static __u32 lod_gen_component_id(struct lod_object *lo,
                                  int mirror_id, int comp_idx);

/**
 * Repeat an existing component
 *
 * Creates a new layout by replicating an existing component.  Uses striping
 * policy from previous component as a template for the striping for the new
 * new component.
 *
 * New component starts with zero length, will be extended (or removed) before
 * returning layout to client.
 *
 * NB: Reallocates layout components array (lo->ldo_comp_entries), invalidating
 * any pre-existing pointers to components.  Handle with care.
 *
 * \param[in] env       execution environment for this thread
 * \param[in,out] lo    object to update the layout of
 * \param[in] index     index of component to copy
 *
 * \retval      0 on success
 * \retval      negative errno on error
 */
static int lod_layout_repeat_comp(const struct lu_env *env,
                                  struct lod_object *lo, int index)
{
        struct lod_layout_component *lod_comp;
        struct lod_layout_component *new_comp = NULL;
        struct lod_layout_component *comp_array;
        int rc = 0, i, new_cnt = lo->ldo_comp_cnt + 1;
        __u16 mirror_id;
        int offset = 0;
        ENTRY;

        lod_comp = &lo->ldo_comp_entries[index];
        LASSERT(lod_comp_inited(lod_comp) && lod_comp->llc_id != LCME_ID_INVAL);

        CDEBUG(D_LAYOUT, "repeating component %d\n", index);

        OBD_ALLOC(comp_array, sizeof(*comp_array) * new_cnt);
        if (comp_array == NULL)
                GOTO(out, rc = -ENOMEM);

        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                memcpy(&comp_array[i + offset], &lo->ldo_comp_entries[i],
                       sizeof(*comp_array));

                /* Duplicate this component in to the next slot */
                if (i == index) {
                        new_comp = &comp_array[i + 1];
                        memcpy(&comp_array[i + 1], &lo->ldo_comp_entries[i],
                               sizeof(*comp_array));
                        /* We must now skip this new component when copying */
                        offset = 1;
                }
        }

        /* Set up copied component */
        new_comp->llc_flags &= ~LCME_FL_INIT;
        new_comp->llc_stripe = NULL;
        new_comp->llc_stripes_allocated = 0;
        new_comp->llc_stripe_offset = LOV_OFFSET_DEFAULT;
        /* for uninstantiated components, layout gen stores default stripe
         * offset */
        new_comp->llc_layout_gen = lod_comp->llc_stripe_offset;
        /* This makes the repeated component zero-length, placed at the end of
         * the preceding component */
        new_comp->llc_extent.e_start = new_comp->llc_extent.e_end;
        new_comp->llc_timestamp = lod_comp->llc_timestamp;
        new_comp->llc_pool = NULL;

        rc = lod_set_pool(&new_comp->llc_pool, lod_comp->llc_pool);
        if (rc)
                GOTO(out, rc);

        if (new_comp->llc_ostlist.op_array) {
                __u32 *op_array = NULL;

                OBD_ALLOC(op_array, new_comp->llc_ostlist.op_size);
                if (!op_array)
                        GOTO(out, rc = -ENOMEM);
                memcpy(op_array, &new_comp->llc_ostlist.op_array,
                       new_comp->llc_ostlist.op_size);
                new_comp->llc_ostlist.op_array = op_array;
        }

        OBD_FREE(lo->ldo_comp_entries,
                 sizeof(*comp_array) * lo->ldo_comp_cnt);
        lo->ldo_comp_entries = comp_array;
        lo->ldo_comp_cnt = new_cnt;

        /* Generate an id for the new component */
        mirror_id = mirror_id_of(new_comp->llc_id);
        new_comp->llc_id = LCME_ID_INVAL;
        new_comp->llc_id = lod_gen_component_id(lo, mirror_id, index + 1);
        if (new_comp->llc_id == LCME_ID_INVAL)
                GOTO(out, rc = -ERANGE);

        EXIT;
out:
        if (rc)
                OBD_FREE(comp_array, sizeof(*comp_array) * new_cnt);

        return rc;
}

static int lod_layout_data_init(struct lod_thread_info *info, __u32 comp_cnt)
{
        ENTRY;

        /* clear memory region that will be used for layout change */
        memset(&info->lti_layout_attr, 0, sizeof(struct lu_attr));
        info->lti_count = 0;

        if (info->lti_comp_size >= comp_cnt)
                RETURN(0);

        if (info->lti_comp_size > 0) {
                OBD_FREE(info->lti_comp_idx,
                         info->lti_comp_size * sizeof(__u32));
                info->lti_comp_size = 0;
        }

        OBD_ALLOC(info->lti_comp_idx, comp_cnt * sizeof(__u32));
        if (!info->lti_comp_idx)
                RETURN(-ENOMEM);

        info->lti_comp_size = comp_cnt;
        RETURN(0);
}

/**
 * Prepare new layout minus deleted components
 *
 * Removes components marked for deletion (LCME_ID_INVAL) by copying to a new
 * layout and skipping those components.  Removes stripe objects if any exist.
 *
 * NB:
 * Reallocates layout components array (lo->ldo_comp_entries), invalidating
 * any pre-existing pointers to components.
 *
 * Caller is responsible for updating mirror end (ldo_mirror[].lme_end).
 *
 * \param[in] env       execution environment for this thread
 * \param[in,out] lo    object to update the layout of
 * \param[in] th        transaction handle for this operation
 *
 * \retval      # of components deleted
 * \retval      negative errno on error
 */
static int lod_layout_del_prep_layout(const struct lu_env *env,
                                      struct lod_object *lo,
                                      struct thandle *th)
{
        struct lod_layout_component     *lod_comp;
        struct lod_thread_info  *info = lod_env_info(env);
        int rc = 0, i, j, deleted = 0;

        ENTRY;

        rc = lod_layout_data_init(info, lo->ldo_comp_cnt);
        if (rc)
                RETURN(rc);

        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                lod_comp = &lo->ldo_comp_entries[i];

                if (lod_comp->llc_id != LCME_ID_INVAL) {
                        /* Build array of things to keep */
                        info->lti_comp_idx[info->lti_count++] = i;
                        continue;
                }

                lod_obj_set_pool(lo, i, NULL);
                if (lod_comp->llc_ostlist.op_array) {
                        OBD_FREE(lod_comp->llc_ostlist.op_array,
                                 lod_comp->llc_ostlist.op_size);
                        lod_comp->llc_ostlist.op_array = NULL;
                        lod_comp->llc_ostlist.op_size = 0;
                }

                deleted++;
                CDEBUG(D_LAYOUT, "deleting comp %d, left %d\n", i,
                       lo->ldo_comp_cnt - deleted);

                /* No striping info for this component */
                if (lod_comp->llc_stripe == NULL)
                        continue;

                LASSERT(lod_comp->llc_stripe_count > 0);
                for (j = 0; j < lod_comp->llc_stripe_count; j++) {
                        struct dt_object *obj = lod_comp->llc_stripe[j];

                        if (obj == NULL)
                                continue;

                        /* components which are not init have no sub objects
                         * to destroy */
                        if (lod_comp_inited(lod_comp)) {
                                rc = lod_sub_destroy(env, obj, th);
                                if (rc)
                                        GOTO(out, rc);
                        }

                        lu_object_put(env, &obj->do_lu);
                        lod_comp->llc_stripe[j] = NULL;
                }
                OBD_FREE(lod_comp->llc_stripe, sizeof(struct dt_object *) *
                                        lod_comp->llc_stripes_allocated);
                lod_comp->llc_stripe = NULL;
                OBD_FREE(lod_comp->llc_ost_indices,
                         sizeof(__u32) * lod_comp->llc_stripes_allocated);
                lod_comp->llc_ost_indices = NULL;
                lod_comp->llc_stripes_allocated = 0;
        }

        /* info->lti_count has the amount of left components */
        LASSERTF(info->lti_count >= 0 && info->lti_count < lo->ldo_comp_cnt,
                 "left = %d, lo->ldo_comp_cnt %d\n", (int)info->lti_count,
                 (int)lo->ldo_comp_cnt);

        if (info->lti_count > 0) {
                struct lod_layout_component *comp_array;

                OBD_ALLOC(comp_array, sizeof(*comp_array) * info->lti_count);
                if (comp_array == NULL)
                        GOTO(out, rc = -ENOMEM);

                for (i = 0; i < info->lti_count; i++) {
                        memcpy(&comp_array[i],
                               &lo->ldo_comp_entries[info->lti_comp_idx[i]],
                               sizeof(*comp_array));
                }

                OBD_FREE(lo->ldo_comp_entries,
                         sizeof(*comp_array) * lo->ldo_comp_cnt);
                lo->ldo_comp_entries = comp_array;
                lo->ldo_comp_cnt = info->lti_count;
        } else {
                lod_free_comp_entries(lo);
        }

        EXIT;
out:
        return rc ? rc : deleted;
}

/**
 * Delete layout component(s)
 *
 * This function sets up the layout data in the env and does the setattrs
 * required to write out the new layout.  The layout itself is modified in
 * lod_layout_del_prep_layout.
 *
 * \param[in] env       execution environment for this thread
 * \param[in] dt        object
 * \param[in] th        transaction handle
 *
 * \retval      0 on success
 * \retval      negative error number on failure
 */
static int lod_layout_del(const struct lu_env *env, struct dt_object *dt,
                          struct thandle *th)
{
        struct lod_object *lo = lod_dt_obj(dt);
        struct dt_object *next = dt_object_child(dt);
        struct lu_attr *attr = &lod_env_info(env)->lti_attr;
        int rc;

        LASSERT(lo->ldo_is_composite);
        LASSERT(lo->ldo_mirror_count == 1);
        LASSERT(lo->ldo_comp_cnt > 0 && lo->ldo_comp_entries != NULL);

        rc = lod_layout_del_prep_layout(env, lo, th);
        if (rc < 0)
                GOTO(out, rc);

        /* Only do this if we didn't delete all components */
        if (lo->ldo_comp_cnt > 0) {
                lo->ldo_mirrors[0].lme_end = lo->ldo_comp_cnt - 1;
                lod_obj_inc_layout_gen(lo);
        }

        LASSERT(dt_object_exists(dt));
        rc = dt_attr_get(env, next, attr);
        if (rc)
                GOTO(out, rc);

        if (attr->la_size > 0) {
                attr->la_size = 0;
                attr->la_valid = LA_SIZE;
                rc = lod_sub_attr_set(env, next, attr, th);
                if (rc)
                        GOTO(out, rc);
        }

        rc = lod_generate_and_set_lovea(env, lo, th);
        EXIT;
out:
        if (rc)
                lod_striping_free(env, lo);
        return rc;
}


static int lod_get_default_lov_striping(const struct lu_env *env,
                                        struct lod_object *lo,
                                        struct lod_default_striping *lds);
/**
 * Implementation of dt_object_operations::do_xattr_set.
 *
 * Sets specified extended attribute on the object. Three types of EAs are
 * special:
 *   LOV EA - stores striping for a regular file or default striping (when set
 *            on a directory)
 *   LMV EA - stores a marker for the striped directories
 *   DMV EA - stores default directory striping
 *
 * When striping is applied to a non-striped existing object (this is called
 * late striping), then LOD notices the caller wants to turn the object into a
 * striped one. The stripe objects are created and appropriate EA is set:
 * LOV EA storing all the stripes directly or LMV EA storing just a small header
 * with striping configuration.
 *
 * \see dt_object_operations::do_xattr_set() in the API description for details.
 */
static int lod_xattr_set(const struct lu_env *env,
                         struct dt_object *dt, const struct lu_buf *buf,
                         const char *name, int fl, struct thandle *th)
{
        struct dt_object        *next = dt_object_child(dt);
        int                      rc;
        ENTRY;

        if (S_ISDIR(dt->do_lu.lo_header->loh_attr) &&
            strcmp(name, XATTR_NAME_LMV) == 0) {
                rc = lod_dir_striping_create(env, dt, NULL, NULL, th);
                RETURN(rc);
        } else if (S_ISDIR(dt->do_lu.lo_header->loh_attr) &&
                   strncmp(name, XATTR_NAME_LMV, strlen(XATTR_NAME_LMV)) == 0 &&
                   strlen(name) > strlen(XATTR_NAME_LMV) + 1) {
                const char *op = name + strlen(XATTR_NAME_LMV) + 1;

                rc = -ENOTSUPP;
                /*
                 * XATTR_NAME_LMV".add" is never called, but only declared,
                 * because lod_xattr_set_lmv() will do the addition.
                 */
                if (strcmp(op, "del") == 0)
                        rc = lod_dir_layout_delete(env, dt, buf, th);
                else if (strcmp(op, "set") == 0)
                        rc = lod_sub_xattr_set(env, next, buf, XATTR_NAME_LMV,
                                               fl, th);

                RETURN(rc);
        } else if (S_ISDIR(dt->do_lu.lo_header->loh_attr) &&
            strcmp(name, XATTR_NAME_LOV) == 0) {
                struct lod_default_striping *lds = lod_lds_buf_get(env);
                struct lov_user_md_v1 *v1 = buf->lb_buf;
                char pool[LOV_MAXPOOLNAME + 1];
                bool is_del;

                /* get existing striping config */
                rc = lod_get_default_lov_striping(env, lod_dt_obj(dt), lds);
                if (rc)
                        RETURN(rc);

                memset(pool, 0, sizeof(pool));
                if (lds->lds_def_striping_set == 1)
                        lod_layout_get_pool(lds->lds_def_comp_entries,
                                            lds->lds_def_comp_cnt, pool,
                                            sizeof(pool));

                is_del = LOVEA_DELETE_VALUES(v1->lmm_stripe_size,
                                             v1->lmm_stripe_count,
                                             v1->lmm_stripe_offset,
                                             NULL);

                /* Retain the pool name if it is not given */
                if (v1->lmm_magic == LOV_USER_MAGIC_V1 && pool[0] != '\0' &&
                        !is_del) {
                        struct lod_thread_info *info = lod_env_info(env);
                        struct lov_user_md_v3 *v3  = info->lti_ea_store;

                        memset(v3, 0, sizeof(*v3));
                        v3->lmm_magic = cpu_to_le32(LOV_USER_MAGIC_V3);
                        v3->lmm_pattern = cpu_to_le32(v1->lmm_pattern);
                        v3->lmm_stripe_count =
                                        cpu_to_le32(v1->lmm_stripe_count);
                        v3->lmm_stripe_offset =
                                        cpu_to_le32(v1->lmm_stripe_offset);
                        v3->lmm_stripe_size = cpu_to_le32(v1->lmm_stripe_size);

                        strlcpy(v3->lmm_pool_name, pool,
                                sizeof(v3->lmm_pool_name));

                        info->lti_buf.lb_buf = v3;
                        info->lti_buf.lb_len = sizeof(*v3);
                        rc = lod_xattr_set_lov_on_dir(env, dt, &info->lti_buf,
                                                      name, fl, th);
                } else {
                        rc = lod_xattr_set_lov_on_dir(env, dt, buf, name,
                                                      fl, th);
                }

                if (lds->lds_def_striping_set == 1 &&
                    lds->lds_def_comp_entries != NULL)
                        lod_free_def_comp_entries(lds);

                RETURN(rc);
        } else if (S_ISDIR(dt->do_lu.lo_header->loh_attr) &&
                   strcmp(name, XATTR_NAME_DEFAULT_LMV) == 0) {
                /* default LMVEA */
                rc = lod_xattr_set_default_lmv_on_dir(env, dt, buf, name, fl,
                                                      th);
                RETURN(rc);
        } else if (S_ISREG(dt->do_lu.lo_header->loh_attr) &&
                   (!strcmp(name, XATTR_NAME_LOV) ||
                    !strncmp(name, XATTR_LUSTRE_LOV,
                             strlen(XATTR_LUSTRE_LOV)))) {
                /* in case of lov EA swap, just set it
                 * if not, it is a replay so check striping match what we
                 * already have during req replay, declare_xattr_set()
                 * defines striping, then create() does the work */
                if (fl & LU_XATTR_REPLACE) {
                        /* free stripes, then update disk */
                        lod_striping_free(env, lod_dt_obj(dt));

                        rc = lod_sub_xattr_set(env, next, buf, name, fl, th);
                } else if (dt_object_remote(dt)) {
                        /* This only happens during migration, see
                         * mdd_migrate_create(), in which Master MDT will
                         * create a remote target object, and only set
                         * (migrating) stripe EA on the remote object,
                         * and does not need creating each stripes. */
                        rc = lod_sub_xattr_set(env, next, buf, name,
                                                      fl, th);
                } else if (strcmp(name, XATTR_LUSTRE_LOV".del") == 0) {
                        /* delete component(s) */
                        LASSERT(lod_dt_obj(dt)->ldo_comp_cached);
                        rc = lod_layout_del(env, dt, th);
                } else {
                        /*
                         * When 'name' is XATTR_LUSTRE_LOV or XATTR_NAME_LOV,
                         * it's going to create create file with specified
                         * component(s), the striping must have not being
                         * cached in this case;
                         *
                         * Otherwise, it's going to add/change component(s) to
                         * an existing file, the striping must have been cached
                         * in this case.
                         */
                        LASSERT(equi(!strcmp(name, XATTR_LUSTRE_LOV) ||
                                     !strcmp(name, XATTR_NAME_LOV),
                                !lod_dt_obj(dt)->ldo_comp_cached));

                        rc = lod_striped_create(env, dt, NULL, NULL, th);
                }
                RETURN(rc);
        } else if (strcmp(name, XATTR_NAME_FID) == 0) {
                rc = lod_replace_parent_fid(env, dt, buf, th, false);

                RETURN(rc);
        }

        /* then all other xattr */
        rc = lod_xattr_set_internal(env, dt, buf, name, fl, th);

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_declare_xattr_del.
 *
 * \see dt_object_operations::do_declare_xattr_del() in the API description
 * for details.
 */
static int lod_declare_xattr_del(const struct lu_env *env,
                                 struct dt_object *dt, const char *name,
                                 struct thandle *th)
{
        struct lod_object *lo = lod_dt_obj(dt);
        struct dt_object *next = dt_object_child(dt);
        int i;
        int rc;
        ENTRY;

        rc = lod_sub_declare_xattr_del(env, next, name, th);
        if (rc != 0)
                RETURN(rc);

        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(0);

        /* set xattr to each stripes, if needed */
        rc = lod_striping_load(env, lo);
        if (rc != 0)
                RETURN(rc);

        if (lo->ldo_dir_stripe_count == 0)
                RETURN(0);

        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                struct dt_object *dto = lo->ldo_stripe[i];

                if (!dto)
                        continue;

                rc = lod_sub_declare_xattr_del(env, dto, name, th);
                if (rc != 0)
                        break;
        }

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_xattr_del.
 *
 * If EA storing a regular striping is being deleted, then release
 * all the references to the stripe objects in core.
 *
 * \see dt_object_operations::do_xattr_del() in the API description for details.
 */
static int lod_xattr_del(const struct lu_env *env, struct dt_object *dt,
                         const char *name, struct thandle *th)
{
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
        int                     rc;
        int                     i;
        ENTRY;

        if (!strcmp(name, XATTR_NAME_LOV) || !strcmp(name, XATTR_NAME_LMV))
                lod_striping_free(env, lod_dt_obj(dt));

        rc = lod_sub_xattr_del(env, next, name, th);
        if (rc != 0 || !S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(rc);

        if (lo->ldo_dir_stripe_count == 0)
                RETURN(0);

        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                struct dt_object *dto = lo->ldo_stripe[i];

                if (!dto)
                        continue;

                rc = lod_sub_xattr_del(env, dto, name, th);
                if (rc != 0)
                        break;
        }

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_xattr_list.
 *
 * \see dt_object_operations::do_xattr_list() in the API description
 * for details.
 */
static int lod_xattr_list(const struct lu_env *env,
                          struct dt_object *dt, const struct lu_buf *buf)
{
        return dt_xattr_list(env, dt_object_child(dt), buf);
}

static inline int lod_object_will_be_striped(int is_reg, const struct lu_fid *fid)
{
        return (is_reg && fid_seq(fid) != FID_SEQ_LOCAL_FILE);
}

/**
 * Copy OST list from layout provided by user.
 *
 * \param[in] lod_comp          layout_component to be filled
 * \param[in] v3                LOV EA V3 user data
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
int lod_comp_copy_ost_lists(struct lod_layout_component *lod_comp,
                            struct lov_user_md_v3 *v3)
{
        int j;

        ENTRY;

        if (v3->lmm_stripe_offset == LOV_OFFSET_DEFAULT)
                v3->lmm_stripe_offset = v3->lmm_objects[0].l_ost_idx;

        if (lod_comp->llc_ostlist.op_array) {
                if (lod_comp->llc_ostlist.op_size >=
                    v3->lmm_stripe_count * sizeof(__u32))  {
                        lod_comp->llc_ostlist.op_count =
                                        v3->lmm_stripe_count;
                        goto skip;
                }
                OBD_FREE(lod_comp->llc_ostlist.op_array,
                         lod_comp->llc_ostlist.op_size);
        }

        /* copy ost list from lmm */
        lod_comp->llc_ostlist.op_count = v3->lmm_stripe_count;
        lod_comp->llc_ostlist.op_size = v3->lmm_stripe_count * sizeof(__u32);
        OBD_ALLOC(lod_comp->llc_ostlist.op_array,
                  lod_comp->llc_ostlist.op_size);
        if (!lod_comp->llc_ostlist.op_array)
                RETURN(-ENOMEM);
skip:
        for (j = 0; j < v3->lmm_stripe_count; j++) {
                lod_comp->llc_ostlist.op_array[j] =
                        v3->lmm_objects[j].l_ost_idx;
        }

        RETURN(0);
}


/**
 * Get default striping.
 *
 * \param[in] env               execution environment
 * \param[in] lo                object
 * \param[out] lds              default striping
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_get_default_lov_striping(const struct lu_env *env,
                                        struct lod_object *lo,
                                        struct lod_default_striping *lds)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lov_user_md_v1 *v1 = NULL;
        struct lov_user_md_v3 *v3 = NULL;
        struct lov_comp_md_v1 *comp_v1 = NULL;
        __u16 comp_cnt;
        __u16 mirror_cnt;
        bool composite;
        int rc, i, j;

        ENTRY;

        rc = lod_get_lov_ea(env, lo);
        if (rc < 0)
                RETURN(rc);

        if (rc < (typeof(rc))sizeof(struct lov_user_md))
                RETURN(0);

        v1 = info->lti_ea_store;
        if (v1->lmm_magic == __swab32(LOV_USER_MAGIC_V1)) {
                lustre_swab_lov_user_md_v1(v1);
        } else if (v1->lmm_magic == __swab32(LOV_USER_MAGIC_V3)) {
                v3 = (struct lov_user_md_v3 *)v1;
                lustre_swab_lov_user_md_v3(v3);
        } else if (v1->lmm_magic == __swab32(LOV_USER_MAGIC_SPECIFIC)) {
                v3 = (struct lov_user_md_v3 *)v1;
                lustre_swab_lov_user_md_v3(v3);
                lustre_swab_lov_user_md_objects(v3->lmm_objects,
                                                v3->lmm_stripe_count);
        } else if (v1->lmm_magic == __swab32(LOV_USER_MAGIC_COMP_V1) ||
                   v1->lmm_magic == __swab32(LOV_USER_MAGIC_SEL)) {
                comp_v1 = (struct lov_comp_md_v1 *)v1;
                lustre_swab_lov_comp_md_v1(comp_v1);
        }

        if (v1->lmm_magic != LOV_MAGIC_V3 && v1->lmm_magic != LOV_MAGIC_V1 &&
            v1->lmm_magic != LOV_MAGIC_COMP_V1 &&
            v1->lmm_magic != LOV_MAGIC_SEL &&
            v1->lmm_magic != LOV_USER_MAGIC_SPECIFIC)
                RETURN(-ENOTSUPP);

        if (v1->lmm_magic == LOV_MAGIC_COMP_V1 ||
            v1->lmm_magic == LOV_MAGIC_SEL) {
                comp_v1 = (struct lov_comp_md_v1 *)v1;
                comp_cnt = comp_v1->lcm_entry_count;
                if (comp_cnt == 0)
                        RETURN(-EINVAL);
                mirror_cnt = comp_v1->lcm_mirror_count + 1;
                composite = true;
        } else {
                comp_cnt = 1;
                mirror_cnt = 0;
                composite = false;
        }

        /* realloc default comp entries if necessary */
        rc = lod_def_striping_comp_resize(lds, comp_cnt);
        if (rc < 0)
                RETURN(rc);

        lds->lds_def_comp_cnt = comp_cnt;
        lds->lds_def_striping_is_composite = composite;
        lds->lds_def_mirror_cnt = mirror_cnt;

        for (i = 0; i < comp_cnt; i++) {
                struct lod_layout_component *lod_comp;
                char *pool;

                lod_comp = &lds->lds_def_comp_entries[i];
                /*
                 * reset lod_comp values, llc_stripes is always NULL in
                 * the default striping template, llc_pool will be reset
                 * later below.
                 */
                memset(lod_comp, 0, offsetof(typeof(*lod_comp), llc_pool));

                if (composite) {
                        v1 = (struct lov_user_md *)((char *)comp_v1 +
                                        comp_v1->lcm_entries[i].lcme_offset);
                        lod_comp->llc_extent =
                                        comp_v1->lcm_entries[i].lcme_extent;
                        /* We only inherit certain flags from the layout */
                        lod_comp->llc_flags =
                                        comp_v1->lcm_entries[i].lcme_flags &
                                        LCME_TEMPLATE_FLAGS;
                }

                if (!lov_pattern_supported(v1->lmm_pattern) &&
                    !(v1->lmm_pattern & LOV_PATTERN_F_RELEASED)) {
                        lod_free_def_comp_entries(lds);
                        RETURN(-EINVAL);
                }

                CDEBUG(D_LAYOUT, DFID" stripe_count=%d stripe_size=%d "
                       "stripe_offset=%d\n",
                       PFID(lu_object_fid(&lo->ldo_obj.do_lu)),
                       (int)v1->lmm_stripe_count, (int)v1->lmm_stripe_size,
                       (int)v1->lmm_stripe_offset);

                lod_comp->llc_stripe_count = v1->lmm_stripe_count;
                lod_comp->llc_stripe_size = v1->lmm_stripe_size;
                lod_comp->llc_stripe_offset = v1->lmm_stripe_offset;
                lod_comp->llc_pattern = v1->lmm_pattern;

                pool = NULL;
                if (v1->lmm_magic == LOV_USER_MAGIC_V3) {
                        /* XXX: sanity check here */
                        v3 = (struct lov_user_md_v3 *) v1;
                        if (v3->lmm_pool_name[0] != '\0')
                                pool = v3->lmm_pool_name;
                }
                lod_set_def_pool(lds, i, pool);
                if (v1->lmm_magic == LOV_USER_MAGIC_SPECIFIC) {
                        v3 = (struct lov_user_md_v3 *)v1;
                        rc = lod_comp_copy_ost_lists(lod_comp, v3);
                        if (rc)
                                RETURN(rc);
                } else if (lod_comp->llc_ostlist.op_array &&
                           lod_comp->llc_ostlist.op_count) {
                        for (j = 0; j < lod_comp->llc_ostlist.op_count; j++)
                                lod_comp->llc_ostlist.op_array[j] = -1;
                        lod_comp->llc_ostlist.op_count = 0;
                }
        }

        lds->lds_def_striping_set = 1;
        RETURN(rc);
}

/**
 * Get default directory striping.
 *
 * \param[in] env               execution environment
 * \param[in] lo                object
 * \param[out] lds              default striping
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_get_default_lmv_striping(const struct lu_env *env,
                                        struct lod_object *lo,
                                        struct lod_default_striping *lds)
{
        struct lmv_user_md *lmu;
        int rc;

        lds->lds_dir_def_striping_set = 0;

        rc = lod_get_default_lmv_ea(env, lo);
        if (rc < 0)
                return rc;

        if (rc >= (int)sizeof(*lmu)) {
                struct lod_thread_info *info = lod_env_info(env);

                lmu = info->lti_ea_store;

                lds->lds_dir_def_stripe_count =
                                le32_to_cpu(lmu->lum_stripe_count);
                lds->lds_dir_def_stripe_offset =
                                le32_to_cpu(lmu->lum_stripe_offset);
                lds->lds_dir_def_hash_type =
                                le32_to_cpu(lmu->lum_hash_type);
                lds->lds_dir_def_striping_set = 1;
        }

        return 0;
}

/**
 * Get default striping in the object.
 *
 * Get object default striping and default directory striping.
 *
 * \param[in] env               execution environment
 * \param[in] lo                object
 * \param[out] lds              default striping
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_get_default_striping(const struct lu_env *env,
                                    struct lod_object *lo,
                                    struct lod_default_striping *lds)
{
        int rc, rc1;

        rc = lod_get_default_lov_striping(env, lo, lds);
        rc1 = lod_get_default_lmv_striping(env, lo, lds);
        if (rc == 0 && rc1 < 0)
                rc = rc1;

        return rc;
}

/**
 * Apply default striping on object.
 *
 * If object striping pattern is not set, set to the one in default striping.
 * The default striping is from parent or fs.
 *
 * \param[in] lo                new object
 * \param[in] lds               default striping
 * \param[in] mode              new object's mode
 */
static void lod_striping_from_default(struct lod_object *lo,
                                      const struct lod_default_striping *lds,
                                      umode_t mode)
{
        struct lod_device *d = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        struct lov_desc *desc = &d->lod_desc;
        int i, rc;

        if (lds->lds_def_striping_set && S_ISREG(mode)) {
                rc = lod_alloc_comp_entries(lo, lds->lds_def_mirror_cnt,
                                            lds->lds_def_comp_cnt);
                if (rc != 0)
                        return;

                lo->ldo_is_composite = lds->lds_def_striping_is_composite;
                if (lds->lds_def_mirror_cnt > 1)
                        lo->ldo_flr_state = LCM_FL_RDONLY;

                for (i = 0; i < lo->ldo_comp_cnt; i++) {
                        struct lod_layout_component *obj_comp =
                                                &lo->ldo_comp_entries[i];
                        struct lod_layout_component *def_comp =
                                                &lds->lds_def_comp_entries[i];

                        CDEBUG(D_LAYOUT, "Inherit from default: flags=%#x "
                               "size=%hu nr=%u offset=%u pattern=%#x pool=%s\n",
                               def_comp->llc_flags,
                               def_comp->llc_stripe_size,
                               def_comp->llc_stripe_count,
                               def_comp->llc_stripe_offset,
                               def_comp->llc_pattern,
                               def_comp->llc_pool ?: "");

                        *obj_comp = *def_comp;
                        if (def_comp->llc_pool != NULL) {
                                /* pointer was copied from def_comp */
                                obj_comp->llc_pool = NULL;
                                lod_obj_set_pool(lo, i, def_comp->llc_pool);
                        }

                        /* copy ost list */
                        if (def_comp->llc_ostlist.op_array &&
                            def_comp->llc_ostlist.op_count) {
                                OBD_ALLOC(obj_comp->llc_ostlist.op_array,
                                          obj_comp->llc_ostlist.op_size);
                                if (!obj_comp->llc_ostlist.op_array)
                                        return;
                                memcpy(obj_comp->llc_ostlist.op_array,
                                       def_comp->llc_ostlist.op_array,
                                       obj_comp->llc_ostlist.op_size);
                        } else if (def_comp->llc_ostlist.op_array) {
                                obj_comp->llc_ostlist.op_array = NULL;
                        }

                        /*
                         * Don't initialize these fields for plain layout
                         * (v1/v3) here, they are inherited in the order of
                         * 'parent' -> 'fs default (root)' -> 'global default
                         * values for stripe_count & stripe_size'.
                         *
                         * see lod_ah_init().
                         */
                        if (!lo->ldo_is_composite)
                                continue;

                        lod_adjust_stripe_info(obj_comp, desc);
                }
        } else if (lds->lds_dir_def_striping_set && S_ISDIR(mode)) {
                if (lo->ldo_dir_stripe_count == 0)
                        lo->ldo_dir_stripe_count =
                                lds->lds_dir_def_stripe_count;
                if (lo->ldo_dir_stripe_offset == -1)
                        lo->ldo_dir_stripe_offset =
                                lds->lds_dir_def_stripe_offset;
                if (lo->ldo_dir_hash_type == 0)
                        lo->ldo_dir_hash_type = lds->lds_dir_def_hash_type &
                                                ~LMV_HASH_FLAG_SPACE;

                CDEBUG(D_LAYOUT, "striping from default dir: count:%hu, "
                       "offset:%u, hash_type:%u\n",
                       lo->ldo_dir_stripe_count, lo->ldo_dir_stripe_offset,
                       lo->ldo_dir_hash_type);
        }
}

static inline bool lod_need_inherit_more(struct lod_object *lo, bool from_root)
{
        struct lod_layout_component *lod_comp;

        if (lo->ldo_comp_cnt == 0)
                return true;

        if (lo->ldo_is_composite)
                return false;

        lod_comp = &lo->ldo_comp_entries[0];

        if (lod_comp->llc_stripe_count <= 0 ||
            lod_comp->llc_stripe_size <= 0)
                return true;

        if (from_root && (lod_comp->llc_pool == NULL ||
                          lod_comp->llc_stripe_offset == LOV_OFFSET_DEFAULT))
                return true;

        return false;
}

/**
 * Implementation of dt_object_operations::do_ah_init.
 *
 * This method is used to make a decision on the striping configuration for the
 * object being created. It can be taken from the \a parent object if it exists,
 * or filesystem's default. The resulting configuration (number of stripes,
 * stripe size/offset, pool name, etc) is stored in the object itself and will
 * be used by the methods like ->doo_declare_create().
 *
 * \see dt_object_operations::do_ah_init() in the API description for details.
 */
static void lod_ah_init(const struct lu_env *env,
                        struct dt_allocation_hint *ah,
                        struct dt_object *parent,
                        struct dt_object *child,
                        umode_t child_mode)
{
        struct lod_device *d = lu2lod_dev(child->do_lu.lo_dev);
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_default_striping *lds = lod_lds_buf_get(env);
        struct dt_object *nextp = NULL;
        struct dt_object *nextc;
        struct lod_object *lp = NULL;
        struct lod_object *lc;
        struct lov_desc *desc;
        struct lod_layout_component *lod_comp;
        int rc;
        ENTRY;

        LASSERT(child);

        if (likely(parent)) {
                nextp = dt_object_child(parent);
                lp = lod_dt_obj(parent);
        }

        nextc = dt_object_child(child);
        lc = lod_dt_obj(child);

        LASSERT(!lod_obj_is_striped(child));
        /* default layout template may have been set on the regular file
         * when this is called from mdd_create_data() */
        if (S_ISREG(child_mode))
                lod_free_comp_entries(lc);

        if (!dt_object_exists(nextc))
                nextc->do_ops->do_ah_init(env, ah, nextp, nextc, child_mode);

        if (S_ISDIR(child_mode)) {
                const struct lmv_user_md_v1 *lum1 = ah->dah_eadata;

                /* other default values are 0 */
                lc->ldo_dir_stripe_offset = -1;

                /* no default striping configuration is needed for
                 * foreign dirs
                 */
                if (ah->dah_eadata != NULL && ah->dah_eadata_len != 0 &&
                    le32_to_cpu(lum1->lum_magic) == LMV_MAGIC_FOREIGN) {
                        lc->ldo_dir_is_foreign = true;
                        /* keep stripe_count 0 and stripe_offset -1 */
                        CDEBUG(D_INFO, "no default striping for foreign dir\n");
                        RETURN_EXIT;
                }

                /*
                 * If parent object is not root directory,
                 * then get default striping from parent object.
                 */
                if (likely(lp != NULL) && !fid_is_root(lod_object_fid(lp)))
                        lod_get_default_striping(env, lp, lds);

                /* set child default striping info, default value is NULL */
                if (lds->lds_def_striping_set || lds->lds_dir_def_striping_set)
                        lc->ldo_def_striping = lds;

                /* It should always honour the specified stripes */
                /* Note: old client (< 2.7)might also do lfs mkdir, whose EA
                 * will have old magic. In this case, we should ignore the
                 * stripe count and try to create dir by default stripe.
                 */
                if (ah->dah_eadata != NULL && ah->dah_eadata_len != 0 &&
                    (le32_to_cpu(lum1->lum_magic) == LMV_USER_MAGIC ||
                     le32_to_cpu(lum1->lum_magic) == LMV_USER_MAGIC_SPECIFIC)) {
                        lc->ldo_dir_stripe_count =
                                le32_to_cpu(lum1->lum_stripe_count);
                        lc->ldo_dir_stripe_offset =
                                le32_to_cpu(lum1->lum_stripe_offset);
                        lc->ldo_dir_hash_type =
                                le32_to_cpu(lum1->lum_hash_type);
                        CDEBUG(D_INFO,
                               "set dirstripe: count %hu, offset %d, hash %u\n",
                                lc->ldo_dir_stripe_count,
                                (int)lc->ldo_dir_stripe_offset,
                                lc->ldo_dir_hash_type);
                } else {
                        /* transfer defaults LMV to new directory */
                        lod_striping_from_default(lc, lds, child_mode);

                        /* set count 0 to create normal directory */
                        if (lc->ldo_dir_stripe_count == 1)
                                lc->ldo_dir_stripe_count = 0;
                }

                /* shrink the stripe_count to the avaible MDT count */
                if (lc->ldo_dir_stripe_count > d->lod_remote_mdt_count + 1 &&
                    !OBD_FAIL_CHECK(OBD_FAIL_LARGE_STRIPE)) {
                        lc->ldo_dir_stripe_count = d->lod_remote_mdt_count + 1;
                        if (lc->ldo_dir_stripe_count == 1)
                                lc->ldo_dir_stripe_count = 0;
                }

                CDEBUG(D_INFO, "final dir stripe [%hu %d %u]\n",
                       lc->ldo_dir_stripe_count,
                       (int)lc->ldo_dir_stripe_offset, lc->ldo_dir_hash_type);

                RETURN_EXIT;
        }

        /* child object regular file*/

        if (!lod_object_will_be_striped(S_ISREG(child_mode),
                                        lu_object_fid(&child->do_lu)))
                RETURN_EXIT;

        /* If object is going to be striped over OSTs, transfer default
         * striping information to the child, so that we can use it
         * during declaration and creation.
         *
         * Try from the parent first.
         */
        if (likely(lp != NULL)) {
                rc = lod_get_default_lov_striping(env, lp, lds);
                if (rc == 0)
                        lod_striping_from_default(lc, lds, child_mode);
        }

        /* Initialize lod_device::lod_md_root object reference */
        if (d->lod_md_root == NULL) {
                struct dt_object *root;
                struct lod_object *lroot;

                lu_root_fid(&info->lti_fid);
                root = dt_locate(env, &d->lod_dt_dev, &info->lti_fid);
                if (!IS_ERR(root)) {
                        lroot = lod_dt_obj(root);

                        spin_lock(&d->lod_lock);
                        if (d->lod_md_root != NULL)
                                dt_object_put(env, &d->lod_md_root->ldo_obj);
                        d->lod_md_root = lroot;
                        spin_unlock(&d->lod_lock);
                }
        }

        /* try inherit layout from the root object (fs default) when:
         *  - parent does not have default layout; or
         *  - parent has plain(v1/v3) default layout, and some attributes
         *    are not specified in the default layout;
         */
        if (d->lod_md_root != NULL && lod_need_inherit_more(lc, true)) {
                rc = lod_get_default_lov_striping(env, d->lod_md_root, lds);
                if (rc)
                        goto out;
                if (lc->ldo_comp_cnt == 0) {
                        lod_striping_from_default(lc, lds, child_mode);
                } else if (!lds->lds_def_striping_is_composite) {
                        struct lod_layout_component *def_comp;

                        LASSERT(!lc->ldo_is_composite);
                        lod_comp = &lc->ldo_comp_entries[0];
                        def_comp = &lds->lds_def_comp_entries[0];

                        if (lod_comp->llc_stripe_count <= 0)
                                lod_comp->llc_stripe_count =
                                        def_comp->llc_stripe_count;
                        if (lod_comp->llc_stripe_size <= 0)
                                lod_comp->llc_stripe_size =
                                        def_comp->llc_stripe_size;
                        if (lod_comp->llc_stripe_offset == LOV_OFFSET_DEFAULT &&
                            (!lod_comp->llc_pool || !lod_comp->llc_pool[0]))
                                lod_comp->llc_stripe_offset =
                                        def_comp->llc_stripe_offset;
                        if (lod_comp->llc_pool == NULL)
                                lod_obj_set_pool(lc, 0, def_comp->llc_pool);
                }
        }
out:
        /*
         * fs default striping may not be explicitly set, or historically set
         * in config log, use them.
         */
        if (lod_need_inherit_more(lc, false)) {
                if (lc->ldo_comp_cnt == 0) {
                        rc = lod_alloc_comp_entries(lc, 0, 1);
                        if (rc)
                                /* fail to allocate memory, will create a
                                 * non-striped file. */
                                RETURN_EXIT;
                        lc->ldo_is_composite = 0;
                        lod_comp = &lc->ldo_comp_entries[0];
                        lod_comp->llc_stripe_offset = LOV_OFFSET_DEFAULT;
                }
                LASSERT(!lc->ldo_is_composite);
                lod_comp = &lc->ldo_comp_entries[0];
                desc = &d->lod_desc;
                lod_adjust_stripe_info(lod_comp, desc);
        }

        EXIT;
}

#define ll_do_div64(aaa,bbb)    do_div((aaa), (bbb))
/**
 * Size initialization on late striping.
 *
 * Propagate the size of a truncated object to a deferred striping.
 * This function handles a special case when truncate was done on a
 * non-striped object and now while the striping is being created
 * we can't lose that size, so we have to propagate it to the stripes
 * being created.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
static int lod_declare_init_size(const struct lu_env *env,
                                 struct dt_object *dt, struct thandle *th)
{
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
        struct dt_object        **objects = NULL;
        struct lu_attr  *attr = &lod_env_info(env)->lti_attr;
        uint64_t        size, offs;
        int     i, rc, stripe, stripe_count = 0, stripe_size = 0;
        struct lu_extent size_ext;
        ENTRY;

        if (!lod_obj_is_striped(dt))
                RETURN(0);

        rc = dt_attr_get(env, next, attr);
        LASSERT(attr->la_valid & LA_SIZE);
        if (rc)
                RETURN(rc);

        size = attr->la_size;
        if (size == 0)
                RETURN(0);

        size_ext = (typeof(size_ext)){ .e_start = size - 1, .e_end = size };
        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                struct lod_layout_component *lod_comp;
                struct lu_extent *extent;

                lod_comp = &lo->ldo_comp_entries[i];

                if (lod_comp->llc_stripe == NULL)
                        continue;

                extent = &lod_comp->llc_extent;
                CDEBUG(D_INFO, "%lld "DEXT"\n", size, PEXT(extent));
                if (!lo->ldo_is_composite ||
                    lu_extent_is_overlapped(extent, &size_ext)) {
                        objects = lod_comp->llc_stripe;
                        stripe_count = lod_comp->llc_stripe_count;
                        stripe_size = lod_comp->llc_stripe_size;

                        /* next mirror */
                        if (stripe_count == 0)
                                continue;

                        LASSERT(objects != NULL && stripe_size != 0);
                        /* ll_do_div64(a, b) returns a % b, and a = a / b */
                        ll_do_div64(size, (__u64)stripe_size);
                        stripe = ll_do_div64(size, (__u64)stripe_count);
                        LASSERT(objects[stripe] != NULL);

                        size = size * stripe_size;
                        offs = attr->la_size;
                        size += ll_do_div64(offs, stripe_size);

                        attr->la_valid = LA_SIZE;
                        attr->la_size = size;

                        rc = lod_sub_declare_attr_set(env, objects[stripe],
                                                      attr, th);
                }
        }

        RETURN(rc);
}

/**
 * Declare creation of striped object.
 *
 * The function declares creation stripes for a regular object. The function
 * also declares whether the stripes will be created with non-zero size if
 * previously size was set non-zero on the master object. If object \a dt is
 * not local, then only fully defined striping can be applied in \a lovea.
 * Otherwise \a lovea can be in the form of pattern, see lod_qos_parse_config()
 * for the details.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] attr      attributes the stripes will be created with
 * \param[in] lovea     a buffer containing striping description
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
int lod_declare_striped_create(const struct lu_env *env, struct dt_object *dt,
                               struct lu_attr *attr,
                               const struct lu_buf *lovea, struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct dt_object        *next = dt_object_child(dt);
        struct lod_object       *lo = lod_dt_obj(dt);
        int                      rc;
        ENTRY;

        if (OBD_FAIL_CHECK(OBD_FAIL_MDS_ALLOC_OBDO))
                GOTO(out, rc = -ENOMEM);

        if (!dt_object_remote(next)) {
                /* choose OST and generate appropriate objects */
                rc = lod_prepare_create(env, lo, attr, lovea, th);
                if (rc)
                        GOTO(out, rc);

                /*
                 * declare storage for striping data
                 */
                info->lti_buf.lb_len = lod_comp_md_size(lo, false);
        } else {
                /* LOD can not choose OST objects for remote objects, i.e.
                 * stripes must be ready before that. Right now, it can only
                 * happen during migrate, i.e. migrate process needs to create
                 * remote regular file (mdd_migrate_create), then the migrate
                 * process will provide stripeEA. */
                LASSERT(lovea != NULL);
                info->lti_buf = *lovea;
        }

        rc = lod_sub_declare_xattr_set(env, next, &info->lti_buf,
                                       XATTR_NAME_LOV, 0, th);
        if (rc)
                GOTO(out, rc);

        /*
         * if striping is created with local object's size > 0,
         * we have to propagate this size to specific object
         * the case is possible only when local object was created previously
         */
        if (dt_object_exists(next))
                rc = lod_declare_init_size(env, dt, th);

out:
        /* failed to create striping or to set initial size, let's reset
         * config so that others don't get confused */
        if (rc)
                lod_striping_free(env, lo);

        RETURN(rc);
}

/*
 * Whether subdirectories under \a dt should be created on MDTs by space QoS
 *
 * If LMV_HASH_FLAG_SPACE is set on directory default layout, its subdirectories
 * should be created on MDT by space QoS.
 *
 * \param[in] env       execution environment
 * \param[in] dev       lu device
 * \param[in] dt        object
 *
 * \retval              1 if directory should create subdir by space usage
 * \retval              0 if not
 * \retval              -ev if failed
 */
static inline int dt_object_qos_mkdir(const struct lu_env *env,
                                      struct lu_device *dev,
                                      struct dt_object *dt)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lu_object *obj;
        struct lod_object *lo;
        struct lmv_user_md *lmu;
        int rc;

        obj = lu_object_find_slice(env, dev, lu_object_fid(&dt->do_lu), NULL);
        if (IS_ERR(obj))
                return PTR_ERR(obj);

        lo = lu2lod_obj(obj);

        rc = lod_get_default_lmv_ea(env, lo);
        dt_object_put(env, dt);
        if (rc <= 0)
                return rc;

        if (rc < (int)sizeof(*lmu))
                return -EINVAL;

        lmu = info->lti_ea_store;
        return !!(le32_to_cpu(lmu->lum_hash_type) & LMV_HASH_FLAG_SPACE);
}

/**
 * Implementation of dt_object_operations::do_declare_create.
 *
 * The method declares creation of a new object. If the object will be striped,
 * then helper functions are called to find FIDs for the stripes, declare
 * creation of the stripes and declare initialization of the striping
 * information to be stored in the master object.
 *
 * \see dt_object_operations::do_declare_create() in the API description
 * for details.
 */
static int lod_declare_create(const struct lu_env *env, struct dt_object *dt,
                              struct lu_attr *attr,
                              struct dt_allocation_hint *hint,
                              struct dt_object_format *dof, struct thandle *th)
{
        struct dt_object   *next = dt_object_child(dt);
        struct lod_object  *lo = lod_dt_obj(dt);
        int                 rc;
        ENTRY;

        LASSERT(dof);
        LASSERT(attr);
        LASSERT(th);

        /*
         * first of all, we declare creation of local object
         */
        rc = lod_sub_declare_create(env, next, attr, hint, dof, th);
        if (rc != 0)
                GOTO(out, rc);

        /*
         * it's lod_ah_init() that has decided the object will be striped
         */
        if (dof->dof_type == DFT_REGULAR) {
                /* callers don't want stripes */
                /* XXX: all tricky interactions with ->ah_make_hint() decided
                 * to use striping, then ->declare_create() behaving differently
                 * should be cleaned */
                if (dof->u.dof_reg.striped != 0)
                        rc = lod_declare_striped_create(env, dt, attr,
                                                        NULL, th);
        } else if (dof->dof_type == DFT_DIR) {
                struct seq_server_site *ss;
                struct lu_buf buf = { NULL };
                struct lu_buf *lmu = NULL;

                ss = lu_site2seq(dt->do_lu.lo_dev->ld_site);

                /* If the parent has default stripeEA, and client
                 * did not find it before sending create request,
                 * then MDT will return -EREMOTE, and client will
                 * retrieve the default stripeEA and re-create the
                 * sub directory.
                 *
                 * Note: if dah_eadata != NULL, it means creating the
                 * striped directory with specified stripeEA, then it
                 * should ignore the default stripeEA */
                if (hint != NULL && hint->dah_eadata == NULL) {
                        if (OBD_FAIL_CHECK(OBD_FAIL_MDS_STALE_DIR_LAYOUT))
                                GOTO(out, rc = -EREMOTE);

                        if (lo->ldo_dir_stripe_offset == -1) {
                                /*
                                 * child and parent should be in the same MDT,
                                 * but if parent has plain layout, it's allowed.
                                 */
                                if (hint->dah_parent &&
                                    dt_object_remote(hint->dah_parent)) {
                                        rc = dt_object_qos_mkdir(env,
                                                       lo->ldo_obj.do_lu.lo_dev,
                                                       hint->dah_parent);
                                        if (rc <= 0)
                                                GOTO(out, rc ? rc : -EREMOTE);
                                }
                        } else if (lo->ldo_dir_stripe_offset !=
                                   ss->ss_node_id) {
                                struct lod_device *lod;
                                struct lod_tgt_descs *ltd;
                                struct lod_tgt_desc *tgt = NULL;
                                bool found_mdt = false;
                                int i;

                                lod = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
                                ltd = &lod->lod_mdt_descs;
                                cfs_foreach_bit(ltd->ltd_tgt_bitmap, i) {
                                        tgt = LTD_TGT(ltd, i);
                                        if (tgt->ltd_index ==
                                                lo->ldo_dir_stripe_offset) {
                                                found_mdt = true;
                                                break;
                                        }
                                }

                                /* If the MDT indicated by stripe_offset can be
                                 * found, then tell client to resend the create
                                 * request to the correct MDT, otherwise return
                                 * error to client */
                                if (found_mdt)
                                        GOTO(out, rc = -EREMOTE);
                                else
                                        GOTO(out, rc = -EINVAL);
                        }
                } else if (hint && hint->dah_eadata) {
                        lmu = &buf;
                        lmu->lb_buf = (void *)hint->dah_eadata;
                        lmu->lb_len = hint->dah_eadata_len;
                }

                rc = lod_declare_dir_striping_create(env, dt, attr, lmu, dof,
                                                     th);
        }
out:
        /* failed to create striping or to set initial size, let's reset
         * config so that others don't get confused */
        if (rc)
                lod_striping_free(env, lo);
        RETURN(rc);
}

/**
 * Generate component ID for new created component.
 *
 * \param[in] lo                LOD object
 * \param[in] comp_idx          index of ldo_comp_entries
 *
 * \retval                      component ID on success
 * \retval                      LCME_ID_INVAL on failure
 */
static __u32 lod_gen_component_id(struct lod_object *lo,
                                  int mirror_id, int comp_idx)
{
        struct lod_layout_component *lod_comp;
        __u32   id, start, end;
        int     i;

        LASSERT(lo->ldo_comp_entries[comp_idx].llc_id == LCME_ID_INVAL);

        lod_obj_inc_layout_gen(lo);
        id = lo->ldo_layout_gen;
        if (likely(id <= SEQ_ID_MAX))
                RETURN(pflr_id(mirror_id, id & SEQ_ID_MASK));

        /* Layout generation wraps, need to check collisions. */
        start = id & SEQ_ID_MASK;
        end = SEQ_ID_MAX;
again:
        for (id = start; id <= end; id++) {
                for (i = 0; i < lo->ldo_comp_cnt; i++) {
                        lod_comp = &lo->ldo_comp_entries[i];
                        if (pflr_id(mirror_id, id) == lod_comp->llc_id)
                                break;
                }
                /* Found the ununsed ID */
                if (i == lo->ldo_comp_cnt)
                        RETURN(pflr_id(mirror_id, id));
        }
        if (end == LCME_ID_MAX) {
                start = 1;
                end = min(lo->ldo_layout_gen & LCME_ID_MASK,
                          (__u32)(LCME_ID_MAX - 1));
                goto again;
        }

        RETURN(LCME_ID_INVAL);
}

/**
 * Creation of a striped regular object.
 *
 * The function is called to create the stripe objects for a regular
 * striped file. This can happen at the initial object creation or
 * when the caller asks LOD to do so using ->do_xattr_set() method
 * (so called late striping). Notice all the information are already
 * prepared in the form of the list of objects (ldo_stripe field).
 * This is done during declare phase.
 *
 * \param[in] env       execution environment
 * \param[in] dt        object
 * \param[in] attr      attributes the stripes will be created with
 * \param[in] dof       format of stripes (see OSD API description)
 * \param[in] th        transaction handle
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
int lod_striped_create(const struct lu_env *env, struct dt_object *dt,
                       struct lu_attr *attr, struct dt_object_format *dof,
                       struct thandle *th)
{
        struct lod_layout_component     *lod_comp;
        struct lod_object       *lo = lod_dt_obj(dt);
        __u16   mirror_id;
        int     rc = 0, i, j;
        ENTRY;

        LASSERT((lo->ldo_comp_cnt != 0 && lo->ldo_comp_entries != NULL) ||
                lo->ldo_is_foreign);

        mirror_id = 0; /* non-flr file's mirror_id is 0 */
        if (lo->ldo_mirror_count > 1) {
                for (i = 0; i < lo->ldo_comp_cnt; i++) {
                        lod_comp = &lo->ldo_comp_entries[i];
                        if (lod_comp->llc_id != LCME_ID_INVAL &&
                            mirror_id_of(lod_comp->llc_id) > mirror_id)
                                mirror_id = mirror_id_of(lod_comp->llc_id);
                }
        }

        /* create all underlying objects */
        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                lod_comp = &lo->ldo_comp_entries[i];

                if (lod_comp->llc_id == LCME_ID_INVAL) {
                        /* only the component of FLR layout with more than 1
                         * mirror has mirror ID in its component ID.
                         */
                        if (lod_comp->llc_extent.e_start == 0 &&
                            lo->ldo_mirror_count > 1)
                                ++mirror_id;

                        lod_comp->llc_id = lod_gen_component_id(lo,
                                                                mirror_id, i);
                        if (lod_comp->llc_id == LCME_ID_INVAL)
                                GOTO(out, rc = -ERANGE);
                }

                if (lod_comp_inited(lod_comp))
                        continue;

                if (lod_comp->llc_pattern & LOV_PATTERN_F_RELEASED)
                        lod_comp_set_init(lod_comp);

                if (lov_pattern(lod_comp->llc_pattern) == LOV_PATTERN_MDT)
                        lod_comp_set_init(lod_comp);

                if (lod_comp->llc_stripe == NULL)
                        continue;

                LASSERT(lod_comp->llc_stripe_count);
                for (j = 0; j < lod_comp->llc_stripe_count; j++) {
                        struct dt_object *object = lod_comp->llc_stripe[j];
                        LASSERT(object != NULL);
                        rc = lod_sub_create(env, object, attr, NULL, dof, th);
                        if (rc)
                                GOTO(out, rc);
                }
                lod_comp_set_init(lod_comp);
        }

        rc = lod_fill_mirrors(lo);
        if (rc)
                GOTO(out, rc);

        rc = lod_generate_and_set_lovea(env, lo, th);
        if (rc)
                GOTO(out, rc);

        lo->ldo_comp_cached = 1;
        RETURN(0);

out:
        lod_striping_free(env, lo);
        RETURN(rc);
}

static inline bool lod_obj_is_dom(struct dt_object *dt)
{
        struct lod_object *lo = lod_dt_obj(dt);

        if (!dt_object_exists(dt_object_child(dt)))
                return false;

        if (S_ISDIR(dt->do_lu.lo_header->loh_attr))
                return false;

        if (!lo->ldo_comp_cnt)
                return false;

        return (lov_pattern(lo->ldo_comp_entries[0].llc_pattern) ==
                LOV_PATTERN_MDT);
}

/**
 * Implementation of dt_object_operations::do_create.
 *
 * If any of preceeding methods (like ->do_declare_create(),
 * ->do_ah_init(), etc) chose to create a striped object,
 * then this method will create the master and the stripes.
 *
 * \see dt_object_operations::do_create() in the API description for details.
 */
static int lod_create(const struct lu_env *env, struct dt_object *dt,
                      struct lu_attr *attr, struct dt_allocation_hint *hint,
                      struct dt_object_format *dof, struct thandle *th)
{
        int                 rc;
        ENTRY;

        /* create local object */
        rc = lod_sub_create(env, dt_object_child(dt), attr, hint, dof, th);
        if (rc != 0)
                RETURN(rc);

        if (S_ISREG(dt->do_lu.lo_header->loh_attr) &&
            (lod_obj_is_striped(dt) || lod_obj_is_dom(dt)) &&
            dof->u.dof_reg.striped != 0) {
                LASSERT(lod_dt_obj(dt)->ldo_comp_cached == 0);
                rc = lod_striped_create(env, dt, attr, dof, th);
        }

        RETURN(rc);
}

static inline int
lod_obj_stripe_destroy_cb(const struct lu_env *env, struct lod_object *lo,
                          struct dt_object *dt, struct thandle *th,
                          int comp_idx, int stripe_idx,
                          struct lod_obj_stripe_cb_data *data)
{
        if (data->locd_declare)
                return lod_sub_declare_destroy(env, dt, th);
        else if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_SPEOBJ) ||
                 stripe_idx == cfs_fail_val)
                return lod_sub_destroy(env, dt, th);
        else
                return 0;
}

/**
 * Implementation of dt_object_operations::do_declare_destroy.
 *
 * If the object is a striped directory, then the function declares reference
 * removal from the master object (this is an index) to the stripes and declares
 * destroy of all the stripes. In all the cases, it declares an intention to
 * destroy the object itself.
 *
 * \see dt_object_operations::do_declare_destroy() in the API description
 * for details.
 */
static int lod_declare_destroy(const struct lu_env *env, struct dt_object *dt,
                               struct thandle *th)
{
        struct dt_object *next = dt_object_child(dt);
        struct lod_object *lo = lod_dt_obj(dt);
        struct lod_thread_info *info = lod_env_info(env);
        struct dt_object *stripe;
        char *stripe_name = info->lti_key;
        int rc, i;

        ENTRY;

        /*
         * load striping information, notice we don't do this when object
         * is being initialized as we don't need this information till
         * few specific cases like destroy, chown
         */
        rc = lod_striping_load(env, lo);
        if (rc)
                RETURN(rc);

        /* declare destroy for all underlying objects */
        if (S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
                rc = next->do_ops->do_index_try(env, next,
                                                &dt_directory_features);
                if (rc != 0)
                        RETURN(rc);

                for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                        stripe = lo->ldo_stripe[i];
                        if (!stripe)
                                continue;

                        rc = lod_sub_declare_ref_del(env, next, th);
                        if (rc != 0)
                                RETURN(rc);

                        snprintf(stripe_name, sizeof(info->lti_key),
                                 DFID":%d",
                                 PFID(lu_object_fid(&stripe->do_lu)), i);
                        rc = lod_sub_declare_delete(env, next,
                                        (const struct dt_key *)stripe_name, th);
                        if (rc != 0)
                                RETURN(rc);
                }
        }

        /*
         * we declare destroy for the local object
         */
        rc = lod_sub_declare_destroy(env, next, th);
        if (rc)
                RETURN(rc);

        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_MDTOBJ) ||
            OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_MDTOBJ2))
                RETURN(0);

        if (!lod_obj_is_striped(dt))
                RETURN(0);

        /* declare destroy all striped objects */
        if (S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
                for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                        stripe = lo->ldo_stripe[i];
                        if (!stripe)
                                continue;

                        if (!dt_object_exists(stripe))
                                continue;

                        rc = lod_sub_declare_ref_del(env, stripe, th);
                        if (rc != 0)
                                break;

                        rc = lod_sub_declare_destroy(env, stripe, th);
                        if (rc != 0)
                                break;
                }
        } else {
                struct lod_obj_stripe_cb_data data = { { 0 } };

                data.locd_declare = true;
                data.locd_stripe_cb = lod_obj_stripe_destroy_cb;
                rc = lod_obj_for_each_stripe(env, lo, th, &data);
        }

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_destroy.
 *
 * If the object is a striped directory, then the function removes references
 * from the master object (this is an index) to the stripes and destroys all
 * the stripes. In all the cases, the function destroys the object itself.
 *
 * \see dt_object_operations::do_destroy() in the API description for details.
 */
static int lod_destroy(const struct lu_env *env, struct dt_object *dt,
                       struct thandle *th)
{
        struct dt_object  *next = dt_object_child(dt);
        struct lod_object *lo = lod_dt_obj(dt);
        struct lod_thread_info *info = lod_env_info(env);
        char *stripe_name = info->lti_key;
        struct dt_object *stripe;
        unsigned int i;
        int rc;

        ENTRY;

        /* destroy sub-stripe of master object */
        if (S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
                rc = next->do_ops->do_index_try(env, next,
                                                &dt_directory_features);
                if (rc != 0)
                        RETURN(rc);

                for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                        stripe = lo->ldo_stripe[i];
                        if (!stripe)
                                continue;

                        rc = lod_sub_ref_del(env, next, th);
                        if (rc != 0)
                                RETURN(rc);

                        snprintf(stripe_name, sizeof(info->lti_key), DFID":%d",
                                PFID(lu_object_fid(&stripe->do_lu)), i);

                        CDEBUG(D_INFO, DFID" delete stripe %s "DFID"\n",
                               PFID(lu_object_fid(&dt->do_lu)), stripe_name,
                               PFID(lu_object_fid(&stripe->do_lu)));

                        rc = lod_sub_delete(env, next,
                                       (const struct dt_key *)stripe_name, th);
                        if (rc != 0)
                                RETURN(rc);
                }
        }

        rc = lod_sub_destroy(env, next, th);
        if (rc != 0)
                RETURN(rc);

        if (OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_MDTOBJ) ||
            OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_MDTOBJ2))
                RETURN(0);

        if (!lod_obj_is_striped(dt))
                RETURN(0);

        /* destroy all striped objects */
        if (S_ISDIR(dt->do_lu.lo_header->loh_attr)) {
                for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                        stripe = lo->ldo_stripe[i];
                        if (!stripe)
                                continue;

                        if (!dt_object_exists(stripe))
                                continue;

                        if (!OBD_FAIL_CHECK(OBD_FAIL_LFSCK_LOST_SPEOBJ) ||
                            i == cfs_fail_val) {
                                dt_write_lock(env, stripe, MOR_TGT_CHILD);
                                rc = lod_sub_ref_del(env, stripe, th);
                                dt_write_unlock(env, stripe);
                                if (rc != 0)
                                        break;

                                rc = lod_sub_destroy(env, stripe, th);
                                if (rc != 0)
                                        break;
                        }
                }
        } else {
                struct lod_obj_stripe_cb_data data = { { 0 } };

                data.locd_declare = false;
                data.locd_stripe_cb = lod_obj_stripe_destroy_cb;
                rc = lod_obj_for_each_stripe(env, lo, th, &data);
        }

        RETURN(rc);
}

/**
 * Implementation of dt_object_operations::do_declare_ref_add.
 *
 * \see dt_object_operations::do_declare_ref_add() in the API description
 * for details.
 */
static int lod_declare_ref_add(const struct lu_env *env,
                               struct dt_object *dt, struct thandle *th)
{
        return lod_sub_declare_ref_add(env, dt_object_child(dt), th);
}

/**
 * Implementation of dt_object_operations::do_ref_add.
 *
 * \see dt_object_operations::do_ref_add() in the API description for details.
 */
static int lod_ref_add(const struct lu_env *env,
                       struct dt_object *dt, struct thandle *th)
{
        return lod_sub_ref_add(env, dt_object_child(dt), th);
}

/**
 * Implementation of dt_object_operations::do_declare_ref_del.
 *
 * \see dt_object_operations::do_declare_ref_del() in the API description
 * for details.
 */
static int lod_declare_ref_del(const struct lu_env *env,
                               struct dt_object *dt, struct thandle *th)
{
        return lod_sub_declare_ref_del(env, dt_object_child(dt), th);
}

/**
 * Implementation of dt_object_operations::do_ref_del
 *
 * \see dt_object_operations::do_ref_del() in the API description for details.
 */
static int lod_ref_del(const struct lu_env *env,
                       struct dt_object *dt, struct thandle *th)
{
        return lod_sub_ref_del(env, dt_object_child(dt), th);
}

/**
 * Implementation of dt_object_operations::do_object_sync.
 *
 * \see dt_object_operations::do_object_sync() in the API description
 * for details.
 */
static int lod_object_sync(const struct lu_env *env, struct dt_object *dt,
                           __u64 start, __u64 end)
{
        return dt_object_sync(env, dt_object_child(dt), start, end);
}

/**
 * Implementation of dt_object_operations::do_object_unlock.
 *
 * Used to release LDLM lock(s).
 *
 * \see dt_object_operations::do_object_unlock() in the API description
 * for details.
 */
static int lod_object_unlock(const struct lu_env *env, struct dt_object *dt,
                             struct ldlm_enqueue_info *einfo,
                             union ldlm_policy_data *policy)
{
        struct lod_object *lo = lod_dt_obj(dt);
        struct lustre_handle_array *slave_locks = einfo->ei_cbdata;
        int slave_locks_size;
        int i;
        ENTRY;

        if (slave_locks == NULL)
                RETURN(0);

        LASSERT(S_ISDIR(dt->do_lu.lo_header->loh_attr));
        /* Note: for remote lock for single stripe dir, MDT will cancel
         * the lock by lockh directly */
        LASSERT(!dt_object_remote(dt_object_child(dt)));

        /* locks were unlocked in MDT layer */
        for (i = 0; i < slave_locks->ha_count; i++)
                LASSERT(!lustre_handle_is_used(&slave_locks->ha_handles[i]));

        /*
         * NB, ha_count may not equal to ldo_dir_stripe_count, because dir
         * layout may change, e.g., shrink dir layout after migration.
         */
        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                if (lo->ldo_stripe[i])
                        dt_invalidate(env, lo->ldo_stripe[i]);
        }

        slave_locks_size = offsetof(typeof(*slave_locks),
                                    ha_handles[slave_locks->ha_count]);
        OBD_FREE(slave_locks, slave_locks_size);
        einfo->ei_cbdata = NULL;

        RETURN(0);
}

/**
 * Implementation of dt_object_operations::do_object_lock.
 *
 * Used to get LDLM lock on the non-striped and striped objects.
 *
 * \see dt_object_operations::do_object_lock() in the API description
 * for details.
 */
static int lod_object_lock(const struct lu_env *env,
                           struct dt_object *dt,
                           struct lustre_handle *lh,
                           struct ldlm_enqueue_info *einfo,
                           union ldlm_policy_data *policy)
{
        struct lod_object *lo = lod_dt_obj(dt);
        int slave_locks_size;
        struct lustre_handle_array *slave_locks = NULL;
        int i;
        int rc;
        ENTRY;

        /* remote object lock */
        if (!einfo->ei_enq_slave) {
                LASSERT(dt_object_remote(dt));
                return dt_object_lock(env, dt_object_child(dt), lh, einfo,
                                      policy);
        }

        if (!S_ISDIR(dt->do_lu.lo_header->loh_attr))
                RETURN(-ENOTDIR);

        rc = lod_striping_load(env, lo);
        if (rc != 0)
                RETURN(rc);

        /* No stripes */
        if (lo->ldo_dir_stripe_count <= 1)
                RETURN(0);

        slave_locks_size = offsetof(typeof(*slave_locks),
                                    ha_handles[lo->ldo_dir_stripe_count]);
        /* Freed in lod_object_unlock */
        OBD_ALLOC(slave_locks, slave_locks_size);
        if (!slave_locks)
                RETURN(-ENOMEM);
        slave_locks->ha_count = lo->ldo_dir_stripe_count;

        /* striped directory lock */
        for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                struct lustre_handle lockh;
                struct ldlm_res_id *res_id;
                struct dt_object *stripe;

                stripe = lo->ldo_stripe[i];
                if (!stripe)
                        continue;

                res_id = &lod_env_info(env)->lti_res_id;
                fid_build_reg_res_name(lu_object_fid(&stripe->do_lu), res_id);
                einfo->ei_res_id = res_id;

                if (dt_object_remote(stripe)) {
                        set_bit(i, (void *)slave_locks->ha_map);
                        rc = dt_object_lock(env, stripe, &lockh, einfo, policy);
                } else {
                        struct ldlm_namespace *ns = einfo->ei_namespace;
                        ldlm_blocking_callback blocking = einfo->ei_cb_local_bl;
                        ldlm_completion_callback completion = einfo->ei_cb_cp;
                        __u64 dlmflags = LDLM_FL_ATOMIC_CB;

                        if (einfo->ei_mode == LCK_PW ||
                            einfo->ei_mode == LCK_EX)
                                dlmflags |= LDLM_FL_COS_INCOMPAT;

                        LASSERT(ns != NULL);
                        rc = ldlm_cli_enqueue_local(env, ns, res_id, LDLM_IBITS,
                                                    policy, einfo->ei_mode,
                                                    &dlmflags, blocking,
                                                    completion, NULL,
                                                    NULL, 0, LVB_T_NONE,
                                                    NULL, &lockh);
                }
                if (rc) {
                        while (i--)
                                ldlm_lock_decref_and_cancel(
                                                &slave_locks->ha_handles[i],
                                                einfo->ei_mode);
                        OBD_FREE(slave_locks, slave_locks_size);
                        RETURN(rc);
                }
                slave_locks->ha_handles[i] = lockh;
        }
        einfo->ei_cbdata = slave_locks;

        RETURN(0);
}

/**
 * Implementation of dt_object_operations::do_invalidate.
 *
 * \see dt_object_operations::do_invalidate() in the API description for details
 */
static int lod_invalidate(const struct lu_env *env, struct dt_object *dt)
{
        return dt_invalidate(env, dt_object_child(dt));
}

static int lod_declare_instantiate_components(const struct lu_env *env,
                struct lod_object *lo, struct thandle *th)
{
        struct lod_thread_info *info = lod_env_info(env);
        int i;
        int rc = 0;
        ENTRY;

        LASSERT(info->lti_count < lo->ldo_comp_cnt);

        for (i = 0; i < info->lti_count; i++) {
                rc = lod_qos_prep_create(env, lo, NULL, th,
                                         info->lti_comp_idx[i]);
                if (rc)
                        break;
        }

        if (!rc) {
                info->lti_buf.lb_len = lod_comp_md_size(lo, false);
                rc = lod_sub_declare_xattr_set(env, lod_object_child(lo),
                                &info->lti_buf, XATTR_NAME_LOV, 0, th);
        }

        RETURN(rc);
}

/**
 * Check OSTs for an existing component for further extension
 *
 * Checks if OSTs are still healthy and not out of space.  Gets free space
 * on OSTs (relative to allocation watermark rmb_low) and compares to
 * the proposed new_end for this component.
 *
 * Decides whether or not to extend a component on its current OSTs.
 *
 * \param[in] env               execution environment for this thread
 * \param[in] lo                object we're checking
 * \param[in] index             index of this component
 * \param[in] extension_size    extension size for this component
 * \param[in] extent            layout extent for requested operation
 * \param[in] comp_extent       extension component extent
 * \param[in] write             if this is write operation
 *
 * \retval      true - OK to extend on current OSTs
 * \retval      false - do not extend on current OSTs
 */
static bool lod_sel_osts_allowed(const struct lu_env *env,
                                 struct lod_object *lo,
                                 int index, __u64 extension_size,
                                 struct lu_extent *extent,
                                 struct lu_extent *comp_extent, int write)
{
        struct lod_layout_component *lod_comp = &lo->ldo_comp_entries[index];
        struct lod_device *lod = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        struct obd_statfs *sfs = &lod_env_info(env)->lti_osfs;
        __u64 available = 0;
        __u64 size;
        bool ret = true;
        int i, rc;

        ENTRY;

        LASSERT(lod_comp->llc_stripe_count != 0);

        if (write == 0 ||
            (extent->e_start == 0 && extent->e_end == OBD_OBJECT_EOF)) {
                /* truncate or append */
                size = extension_size;
        } else {
                /* In case of write op, check the real write extent,
                 * it may be larger than the extension_size */
                size = roundup(min(extent->e_end, comp_extent->e_end) -
                               max(extent->e_start, comp_extent->e_start),
                               extension_size);
        }
        /* extension_size is file level, so we must divide by stripe count to
         * compare it to available space on a single OST */
        size /= lod_comp->llc_stripe_count;

        lod_getref(&lod->lod_ost_descs);
        for (i = 0; i < lod_comp->llc_stripe_count; i++) {
                int index = lod_comp->llc_ost_indices[i];
                struct lod_tgt_desc *ost = OST_TGT(lod, index);
                struct obd_statfs_info info = { 0 };
                int j, repeated = 0;

                LASSERT(ost);

                /* Get the number of times this OST repeats in this component.
                 * Note: inter-component repeats are not counted as this is
                 * considered as a rare case: we try to not repeat OST in other
                 * components if possible. */
                for (j = 0; j < lod_comp->llc_stripe_count; j++) {
                        if (index != lod_comp->llc_ost_indices[j])
                                continue;

                        /* already handled */
                        if (j < i)
                                break;

                        repeated++;
                }
                if (j < lod_comp->llc_stripe_count)
                        continue;

                if (!cfs_bitmap_check(lod->lod_ost_bitmap, index)) {
                        CDEBUG(D_LAYOUT, "ost %d no longer present\n", index);
                        ret = false;
                        break;
                }

                rc = dt_statfs(env, ost->ltd_ost, sfs, &info);
                if (rc) {
                        CDEBUG(D_LAYOUT, "statfs failed for ost %d, error %d\n",
                               index, rc);
                        ret = false;
                        break;
                }

                if (sfs->os_state & OS_STATE_ENOSPC ||
                    sfs->os_state & OS_STATE_READONLY ||
                    sfs->os_state & OS_STATE_DEGRADED) {
                        CDEBUG(D_LAYOUT, "ost %d is not availble for SEL "
                               "extension, state %u\n", index, sfs->os_state);
                        ret = false;
                        break;
                }

                /* In bytes */
                available = sfs->os_bavail * sfs->os_bsize;
                /* 'available' is relative to the allocation threshold */
                available -= (__u64) info.os_reserved_mb_low << 20;

                CDEBUG(D_LAYOUT, "ost %d lowwm: %d highwm: %d, "
                       "%llu %% blocks available, %llu %% blocks free\n",
                       index, info.os_reserved_mb_low, info.os_reserved_mb_high,
                       (100ull * sfs->os_bavail) / sfs->os_blocks,
                       (100ull * sfs->os_bfree) / sfs->os_blocks);

                if (size * repeated > available) {
                        ret = false;
                        CDEBUG(D_LAYOUT, "low space on ost %d, available %llu "
                               "< extension size %llu\n", index, available,
                               extension_size);
                        break;
                }
        }
        lod_putref(lod, &lod->lod_ost_descs);

        RETURN(ret);
}

/**
 * Adjust extents after component removal
 *
 * When we remove an extension component, we move the start of the next
 * component to match the start of the extension component, so no space is left
 * without layout.
 *
 * \param[in] env       execution environment for this thread
 * \param[in] lo        object
 * \param[in] max_comp  layout component
 * \param[in] index     index of this component
 *
 * \retval              0 on success
 * \retval              negative errno on error
 */
static void lod_sel_adjust_extents(const struct lu_env *env,
                                   struct lod_object *lo,
                                   int max_comp, int index)
{
        struct lod_layout_component *lod_comp = NULL;
        struct lod_layout_component *next = NULL;
        struct lod_layout_component *prev = NULL;
        __u64 new_start = 0;
        __u64 start;
        int i;

        /* Extension space component */
        lod_comp = &lo->ldo_comp_entries[index];
        next = &lo->ldo_comp_entries[index + 1];
        prev = &lo->ldo_comp_entries[index - 1];

        LASSERT(lod_comp != NULL && prev != NULL && next != NULL);
        LASSERT(lod_comp->llc_flags & LCME_FL_EXTENSION);

        /* Previous is being removed */
        if (prev && prev->llc_id == LCME_ID_INVAL)
                new_start = prev->llc_extent.e_start;
        else
                new_start = lod_comp->llc_extent.e_start;

        for (i = index + 1; i < max_comp; i++) {
                lod_comp = &lo->ldo_comp_entries[i];

                start = lod_comp->llc_extent.e_start;
                lod_comp->llc_extent.e_start = new_start;

                /* We only move zero length extendable components */
                if (!(start == lod_comp->llc_extent.e_end))
                        break;

                LASSERT(!(lod_comp->llc_flags & LCME_FL_INIT));

                lod_comp->llc_extent.e_end = new_start;
        }
}

/* Calculate the proposed 'new end' for a component we're extending */
static __u64 lod_extension_new_end(__u64 extension_size, __u64 extent_end,
                                   __u32 stripe_size, __u64 component_end,
                                   __u64 extension_end)
{
        __u64 new_end;

        LASSERT(extension_size != 0 && stripe_size != 0);

        /* Round up to extension size */
        if (extent_end == OBD_OBJECT_EOF) {
                new_end = OBD_OBJECT_EOF;
        } else {
                /* Add at least extension_size to the previous component_end,
                 * covering the req layout extent */
                new_end = max(extent_end - component_end, extension_size);
                new_end = roundup(new_end, extension_size);
                new_end += component_end;

                /* Component end must be min stripe size aligned */
                if (new_end % stripe_size) {
                        CDEBUG(D_LAYOUT, "new component end is not aligned "
                               "by the stripe size %u: [%llu, %llu) ext size "
                               "%llu new end %llu, aligning\n",
                               stripe_size, component_end, extent_end,
                               extension_size, new_end);
                        new_end = roundup(new_end, stripe_size);
                }

                /* Overflow */
                if (new_end < extent_end)
                        new_end = OBD_OBJECT_EOF;
        }

        /* Don't extend past the end of the extension component */
        if (new_end > extension_end)
                new_end = extension_end;

        return new_end;
}

/* As lod_sel_handler() could be re-entered for the same component several
 * times, this is the data for the next call. Fields could be changed to
 * component indexes when needed, (e.g. if there is no need to instantiate
 * all the previous components up to the current position) to tell the caller
 * where to start over from. */
struct sel_data {
        int sd_force;
        int sd_repeat;
};

/**
 * Process extent updates for a particular layout component
 *
 * Handle layout updates for a particular extension space component touched by
 * a layout update operation.  Core function of self-extending PFL feature.
 *
 * In general, this function processes exactly *one* stage of an extension
 * operation, modifying the layout accordingly, then returns to the caller.
 * The caller is responsible for restarting processing with the new layout,
 * which may repeatedly return to this function until the extension updates
 * are complete.
 *
 * This function does one of a few things to the layout:
 * 1. Extends the component before the current extension space component to
 * allow it to accomodate the requested operation (if space/policy permit that
 * component to continue on its current OSTs)
 *
 * 2. If extension of the existing component fails, we do one of two things:
 *    a. If there is a component after the extension space, we remove the
 *       extension space component, move the start of the next component down
 *       accordingly, then notify the caller to restart processing w/the new
 *       layout.
 *    b. If there is no following component, we try repeating the current
 *       component, creating a new component using the current one as a
 *       template (keeping its stripe properties but not specific striping),
 *       and try assigning striping for this component.  If there is sufficient
 *       free space on the OSTs chosen for this component, it is instantiated
 *       and i/o continues there.
 *
 *       If there is not sufficient space on the new OSTs, we remove this new
 *       component & extend the current component.
 *
 * Note further that uninited components followed by extension space can be zero
 * length meaning that we will try to extend them before initializing them, and
 * if that fails, they will be removed without initialization.
 *
 * 3. If we extend to/beyond the end of an extension space component, that
 * component is exhausted (all of its range has been given to real components),
 * so we remove it and restart processing.
 *
 * \param[in] env               execution environment for this thread
 * \param[in,out] lo            object to update the layout of
 * \param[in] extent            layout extent for requested operation, update
 *                              layout to fit this operation
 * \param[in] th                transaction handle for this operation
 * \param[in,out] max_comp      the highest comp for the portion of the layout
 *                              we are operating on (For FLR, the chosen
 *                              replica).  Updated because we may remove
 *                              components.
 * \param[in] index             index of the extension space component we're
 *                              working on
 * \param[in] write             if this is write op
 * \param[in,out] force         if the extension is to be forced; set here
                                to force it on the 2nd call for the same
                                extension component
 *
 * \retval      0 on success
 * \retval      negative errno on error
 */
static int lod_sel_handler(const struct lu_env *env,
                          struct lod_object *lo,
                          struct lu_extent *extent,
                          struct thandle *th, int *max_comp,
                          int index, int write,
                          struct sel_data *sd)
{
        struct lod_device *d = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_layout_component *lod_comp;
        struct lod_layout_component *prev;
        struct lod_layout_component *next = NULL;
        __u64 extension_size;
        __u64 new_end = 0;
        bool repeated;
        int change = 0;
        int rc = 0;
        ENTRY;

        /* First component cannot be extension space */
        if (index == 0) {
                CERROR("%s: "DFID" first component cannot be extension space\n",
                       lod2obd(d)->obd_name, PFID(lod_object_fid(lo)));
                RETURN(-EINVAL);
        }

        lod_comp = &lo->ldo_comp_entries[index];
        prev = &lo->ldo_comp_entries[index - 1];
        if ((index + 1) < *max_comp)
                next = &lo->ldo_comp_entries[index + 1];

        /* extension size uses the stripe size field as KiB */
        extension_size = lod_comp->llc_stripe_size * SEL_UNIT_SIZE;

        CDEBUG(D_LAYOUT, "prev start %llu, extension start %llu, extension end"
               " %llu, extension size %llu\n", prev->llc_extent.e_start,
               lod_comp->llc_extent.e_start, lod_comp->llc_extent.e_end,
               extension_size);

        /* Two extension space components cannot be adjacent & extension space
         * components cannot be init */
        if ((prev->llc_flags & LCME_FL_EXTENSION) ||
            !(ergo(next, !(next->llc_flags & LCME_FL_EXTENSION))) ||
             lod_comp_inited(lod_comp)) {
                CERROR("%s: "DFID" invalid extension space components\n",
                       lod2obd(d)->obd_name, PFID(lod_object_fid(lo)));
                RETURN(-EINVAL);
        }

        if (!prev->llc_stripe) {
                CDEBUG(D_LAYOUT, "Previous component not inited\n");
                info->lti_count = 1;
                info->lti_comp_idx[0] = index - 1;
                rc = lod_declare_instantiate_components(env, lo, th);
                /* ENOSPC tells us we can't use this component.  If there is
                 * a next or we are repeating, we either spill over (next) or
                 * extend the original comp (repeat).  Otherwise, return the
                 * error to the user. */
                if (rc == -ENOSPC && (next || sd->sd_repeat))
                        rc = 1;
                if (rc < 0)
                        RETURN(rc);
        }

        if (sd->sd_force == 0 && rc == 0)
                rc = !lod_sel_osts_allowed(env, lo, index - 1,
                                           extension_size, extent,
                                           &lod_comp->llc_extent, write);

        repeated = !!(sd->sd_repeat);
        sd->sd_repeat = 0;
        sd->sd_force = 0;

        /* Extend previous component */
        if (rc == 0) {
                new_end = lod_extension_new_end(extension_size, extent->e_end,
                                                prev->llc_stripe_size,
                                                prev->llc_extent.e_end,
                                                lod_comp->llc_extent.e_end);

                CDEBUG(D_LAYOUT, "new end %llu\n", new_end);
                lod_comp->llc_extent.e_start = new_end;
                prev->llc_extent.e_end = new_end;

                if (prev->llc_extent.e_end == lod_comp->llc_extent.e_end) {
                        CDEBUG(D_LAYOUT, "Extension component exhausted\n");
                        lod_comp->llc_id = LCME_ID_INVAL;
                        change--;
                }
        } else {
                /* rc == 1, failed to extend current component */
                LASSERT(rc == 1);
                if (next) {
                        /* Normal 'spillover' case - Remove the extension
                         * space component & bring down the start of the next
                         * component. */
                        lod_comp->llc_id = LCME_ID_INVAL;
                        change--;
                        if (!(prev->llc_flags & LCME_FL_INIT)) {
                                prev->llc_id = LCME_ID_INVAL;
                                change--;
                        }
                        lod_sel_adjust_extents(env, lo, *max_comp, index);
                } else if (lod_comp_inited(prev)) {
                        /* If there is no next, and the previous component is
                         * INIT'ed, try repeating the previous component. */
                        LASSERT(repeated == 0);
                        rc = lod_layout_repeat_comp(env, lo, index - 1);
                        if (rc < 0)
                                RETURN(rc);
                        change++;
                        /* The previous component is a repeated component.
                         * Record this so we don't keep trying to repeat it. */
                        sd->sd_repeat = 1;
                } else {
                        /* If the previous component is not INIT'ed, this may
                         * be a component we have just instantiated but failed
                         * to extend. Or even a repeated component we failed
                         * to prepare a striping for. Do not repeat but instead
                         * remove the repeated component & force the extention
                         * of the original one */
                        sd->sd_force = 1;
                        if (repeated) {
                                prev->llc_id = LCME_ID_INVAL;
                                change--;
                        }
                }
        }

        if (change < 0) {
                rc = lod_layout_del_prep_layout(env, lo, NULL);
                if (rc < 0)
                        RETURN(rc);
                LASSERTF(-rc == change,
                         "number deleted %d != requested %d\n", -rc,
                         change);
        }
        *max_comp = *max_comp + change;

        /* lod_del_prep_layout reallocates ldo_comp_entries, so we must
         * refresh these pointers before using them */
        lod_comp = &lo->ldo_comp_entries[index];
        prev = &lo->ldo_comp_entries[index - 1];
        CDEBUG(D_LAYOUT, "After extent updates: prev start %llu, current start "
               "%llu, current end %llu max_comp %d ldo_comp_cnt %d\n",
               prev->llc_extent.e_start, lod_comp->llc_extent.e_start,
               lod_comp->llc_extent.e_end, *max_comp, lo->ldo_comp_cnt);

        /* Layout changed successfully */
        RETURN(0);
}

/**
 * Declare layout extent updates
 *
 * Handles extensions.  Identifies extension components touched by current
 * operation and passes them to processing function.
 *
 * Restarts with updated layouts from the processing function until the current
 * operation no longer touches an extension space component.
 *
 * \param[in] env       execution environment for this thread
 * \param[in,out] lo    object to update the layout of
 * \param[in] extent    layout extent for requested operation, update layout to
 *                      fit this operation
 * \param[in] th        transaction handle for this operation
 * \param[in] pick      identifies chosen mirror for FLR layouts
 * \param[in] write     if this is write op
 *
 * \retval      1 on layout changed, 0 on no change
 * \retval      negative errno on error
 */
static int lod_declare_update_extents(const struct lu_env *env,
                struct lod_object *lo, struct lu_extent *extent,
                struct thandle *th, int pick, int write)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_layout_component *lod_comp;
        bool layout_changed = false;
        struct sel_data sd = { 0 };
        int start_index;
        int i = 0;
        int max_comp = 0;
        int rc = 0, rc2;
        int change = 0;
        ENTRY;

        /* This makes us work on the components of the chosen mirror */
        start_index = lo->ldo_mirrors[pick].lme_start;
        max_comp = lo->ldo_mirrors[pick].lme_end + 1;
        if (lo->ldo_flr_state == LCM_FL_NONE)
                LASSERT(start_index == 0 && max_comp == lo->ldo_comp_cnt);

        CDEBUG(D_LAYOUT, "extent->e_start %llu, extent->e_end %llu\n",
               extent->e_start, extent->e_end);
        for (i = start_index; i < max_comp; i++) {
                lod_comp = &lo->ldo_comp_entries[i];

                /* We've passed all components of interest */
                if (lod_comp->llc_extent.e_start >= extent->e_end)
                        break;

                if (lod_comp->llc_flags & LCME_FL_EXTENSION) {
                        layout_changed = true;
                        rc = lod_sel_handler(env, lo, extent, th, &max_comp,
                                             i, write, &sd);
                        if (rc < 0)
                                GOTO(out, rc);

                        /* Nothing has changed behind the prev one */
                        i -= 2;
                        continue;
                }
        }

        /* We may have added or removed components.  If so, we must update the
         * start & ends of all the mirrors after the current one, and the end
         * of the current mirror. */
        change = max_comp - 1 - lo->ldo_mirrors[pick].lme_end;
        if (change) {
                lo->ldo_mirrors[pick].lme_end += change;
                for (i = pick + 1; i < lo->ldo_mirror_count; i++) {
                        lo->ldo_mirrors[i].lme_start += change;
                        lo->ldo_mirrors[i].lme_end += change;
                }
        }

        EXIT;
out:
        /* The amount of components has changed, adjust the lti_comp_idx */
        rc2 = lod_layout_data_init(info, lo->ldo_comp_cnt);

        return rc < 0 ? rc : rc2 < 0 ? rc2 : layout_changed;
}

/* If striping is already instantiated or INIT'ed DOM? */
static bool lod_is_instantiation_needed(struct lod_layout_component *comp)
{
        return !(((lov_pattern(comp->llc_pattern) == LOV_PATTERN_MDT) &&
                  lod_comp_inited(comp)) || comp->llc_stripe);
}

/**
 * Declare layout update for a non-FLR layout.
 *
 * \param[in] env       execution environment for this thread
 * \param[in,out] lo    object to update the layout of
 * \param[in] layout    layout intent for requested operation, "update" is
 *                      a process of reacting to this
 * \param[in] buf       buffer containing lov ea (see comment on usage inline)
 * \param[in] th        transaction handle for this operation
 *
 * \retval      0 on success
 * \retval      negative errno on error
 */
static int lod_declare_update_plain(const struct lu_env *env,
                struct lod_object *lo, struct layout_intent *layout,
                const struct lu_buf *buf, struct thandle *th)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_device *d = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        struct lod_layout_component *lod_comp;
        struct lov_comp_md_v1 *comp_v1 = NULL;
        bool layout_changed = false;
        bool replay = false;
        int i, rc;
        ENTRY;

        LASSERT(lo->ldo_flr_state == LCM_FL_NONE);

        /*
         * In case the client is passing lovea, which only happens during
         * the replay of layout intent write RPC for now, we may need to
         * parse the lovea and apply new layout configuration.
         */
        if (buf && buf->lb_len)  {
                struct lov_user_md_v1 *v1 = buf->lb_buf;

                if (v1->lmm_magic != (LOV_MAGIC_DEFINED | LOV_MAGIC_COMP_V1) &&
                    v1->lmm_magic != __swab32(LOV_MAGIC_DEFINED |
                                              LOV_MAGIC_COMP_V1)) {
                        CERROR("%s: the replay buffer of layout extend "
                               "(magic %#x) does not contain expected "
                               "composite layout.\n",
                               lod2obd(d)->obd_name, v1->lmm_magic);
                        GOTO(out, rc = -EINVAL);
                }

                rc = lod_use_defined_striping(env, lo, buf);
                if (rc)
                        GOTO(out, rc);
                lo->ldo_comp_cached = 1;

                rc = lod_get_lov_ea(env, lo);
                if (rc <= 0)
                        GOTO(out, rc);
                /* old on-disk EA is stored in info->lti_buf */
                comp_v1 = (struct lov_comp_md_v1 *)info->lti_buf.lb_buf;
                replay = true;
                layout_changed = true;

                rc = lod_layout_data_init(info, lo->ldo_comp_cnt);
                if (rc)
                        GOTO(out, rc);
        } else {
                /* non replay path */
                rc = lod_striping_load(env, lo);
                if (rc)
                        GOTO(out, rc);
        }

        /* Make sure defined layout covers the requested write range. */
        lod_comp = &lo->ldo_comp_entries[lo->ldo_comp_cnt - 1];
        if (lo->ldo_comp_cnt > 1 &&
            lod_comp->llc_extent.e_end != OBD_OBJECT_EOF &&
            lod_comp->llc_extent.e_end < layout->li_extent.e_end) {
                CDEBUG_LIMIT(replay ? D_ERROR : D_LAYOUT,
                             "%s: the defined layout [0, %#llx) does not "
                             "covers the write range "DEXT"\n",
                             lod2obd(d)->obd_name, lod_comp->llc_extent.e_end,
                             PEXT(&layout->li_extent));
                GOTO(out, rc = -EINVAL);
        }

        CDEBUG(D_LAYOUT, "%s: "DFID": update components "DEXT"\n",
               lod2obd(d)->obd_name, PFID(lod_object_fid(lo)),
               PEXT(&layout->li_extent));

        if (!replay) {
                rc = lod_declare_update_extents(env, lo, &layout->li_extent,
                                th, 0, layout->li_opc == LAYOUT_INTENT_WRITE);
                if (rc < 0)
                        GOTO(out, rc);
                else if (rc)
                        layout_changed = true;
        }

        /*
         * Iterate ld->ldo_comp_entries, find the component whose extent under
         * the write range and not instantianted.
         */
        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                lod_comp = &lo->ldo_comp_entries[i];

                if (lod_comp->llc_extent.e_start >= layout->li_extent.e_end)
                        break;

                if (!replay) {
                        /* If striping is instantiated or INIT'ed DOM skip */
                        if (!lod_is_instantiation_needed(lod_comp))
                                continue;
                } else {
                        /**
                         * In replay path, lod_comp is the EA passed by
                         * client replay buffer,  comp_v1 is the pre-recovery
                         * on-disk EA, we'd sift out those components which
                         * were init-ed in the on-disk EA.
                         */
                        if (le32_to_cpu(comp_v1->lcm_entries[i].lcme_flags) &
                            LCME_FL_INIT)
                                continue;
                }
                /*
                 * this component hasn't instantiated in normal path, or during
                 * replay it needs replay the instantiation.
                 */

                /* A released component is being extended */
                if (lod_comp->llc_pattern & LOV_PATTERN_F_RELEASED)
                        GOTO(out, rc = -EINVAL);

                LASSERT(info->lti_comp_idx != NULL);
                info->lti_comp_idx[info->lti_count++] = i;
                layout_changed = true;
        }

        if (!layout_changed)
                RETURN(-EALREADY);

        lod_obj_inc_layout_gen(lo);
        rc = lod_declare_instantiate_components(env, lo, th);
        EXIT;
out:
        if (rc)
                lod_striping_free(env, lo);
        return rc;
}

static inline int lod_comp_index(struct lod_object *lo,
                                 struct lod_layout_component *lod_comp)
{
        LASSERT(lod_comp >= lo->ldo_comp_entries &&
                lod_comp <= &lo->ldo_comp_entries[lo->ldo_comp_cnt - 1]);

        return lod_comp - lo->ldo_comp_entries;
}

/**
 * Stale other mirrors by writing extent.
 */
static int lod_stale_components(const struct lu_env *env, struct lod_object *lo,
                                int primary, struct lu_extent *extent,
                                struct thandle *th)
{
        struct lod_layout_component *pri_comp, *lod_comp;
        struct lu_extent pri_extent;
        int rc = 0;
        int i;
        ENTRY;

        /* The writing extent decides which components in the primary
         * are affected... */
        CDEBUG(D_LAYOUT, "primary mirror %d, "DEXT"\n", primary, PEXT(extent));

restart:
        lod_foreach_mirror_comp(pri_comp, lo, primary) {
                if (!lu_extent_is_overlapped(extent, &pri_comp->llc_extent))
                        continue;

                CDEBUG(D_LAYOUT, "primary comp %u "DEXT"\n",
                       lod_comp_index(lo, pri_comp),
                       PEXT(&pri_comp->llc_extent));

                pri_extent.e_start = pri_comp->llc_extent.e_start;
                pri_extent.e_end = pri_comp->llc_extent.e_end;

                for (i = 0; i < lo->ldo_mirror_count; i++) {
                        if (i == primary)
                                continue;
                        rc = lod_declare_update_extents(env, lo, &pri_extent,
                                                        th, i, 0);
                        /* if update_extents changed the layout, it may have
                         * reallocated the component array, so start over to
                         * avoid using stale pointers */
                        if (rc == 1)
                                goto restart;
                        if (rc < 0)
                                RETURN(rc);

                        /* ... and then stale other components that are
                         * overlapping with primary components */
                        lod_foreach_mirror_comp(lod_comp, lo, i) {
                                if (!lu_extent_is_overlapped(
                                                        &pri_extent,
                                                        &lod_comp->llc_extent))
                                        continue;

                                CDEBUG(D_LAYOUT, "stale: %u / %u\n",
                                      i, lod_comp_index(lo, lod_comp));

                                lod_comp->llc_flags |= LCME_FL_STALE;
                                lo->ldo_mirrors[i].lme_stale = 1;
                        }
                }
        }

        RETURN(rc);
}

/**
 * check an OST's availability
 * \param[in] env       execution environment
 * \param[in] lo        lod object
 * \param[in] dt        dt object
 * \param[in] index     mirror index
 *
 * \retval      negative if failed
 * \retval      1 if \a dt is available
 * \retval      0 if \a dt is not available
 */
static inline int lod_check_ost_avail(const struct lu_env *env,
                                      struct lod_object *lo,
                                      struct dt_object *dt, int index)
{
        struct lod_device *lod = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        struct lod_tgt_desc *ost;
        __u32 idx;
        int type = LU_SEQ_RANGE_OST;
        int rc;

        rc = lod_fld_lookup(env, lod, lu_object_fid(&dt->do_lu), &idx, &type);
        if (rc < 0) {
                CERROR("%s: can't locate "DFID":rc = %d\n",
                       lod2obd(lod)->obd_name, PFID(lu_object_fid(&dt->do_lu)),
                       rc);
                return rc;
        }

        ost = OST_TGT(lod, idx);
        if (ost->ltd_statfs.os_state &
                (OS_STATE_READONLY | OS_STATE_ENOSPC | OS_STATE_ENOINO |
                 OS_STATE_NOPRECREATE) ||
            ost->ltd_active == 0) {
                CDEBUG(D_LAYOUT, DFID ": mirror %d OST%d unavail, rc = %d\n",
                       PFID(lod_object_fid(lo)), index, idx, rc);
                return 0;
        }

        return 1;
}

/**
 * Pick primary mirror for write
 * \param[in] env       execution environment
 * \param[in] lo        object
 * \param[in] extent    write range
 */
static int lod_primary_pick(const struct lu_env *env, struct lod_object *lo,
                            struct lu_extent *extent)
{
        struct lod_device *lod = lu2lod_dev(lo->ldo_obj.do_lu.lo_dev);
        unsigned int seq = 0;
        struct lod_layout_component *lod_comp;
        int i, j, rc;
        int picked = -1, second_pick = -1, third_pick = -1;
        ENTRY;

        if (OBD_FAIL_CHECK(OBD_FAIL_FLR_RANDOM_PICK_MIRROR)) {
                get_random_bytes(&seq, sizeof(seq));
                seq %= lo->ldo_mirror_count;
        }

        /**
         * Pick a mirror as the primary, and check the availability of OSTs.
         *
         * This algo can be revised later after knowing the topology of
         * cluster.
         */
        lod_qos_statfs_update(env, lod);
        for (i = 0; i < lo->ldo_mirror_count; i++) {
                bool ost_avail = true;
                int index = (i + seq) % lo->ldo_mirror_count;

                if (lo->ldo_mirrors[index].lme_stale) {
                        CDEBUG(D_LAYOUT, DFID": mirror %d stale\n",
                               PFID(lod_object_fid(lo)), index);
                        continue;
                }

                /* 2nd pick is for the primary mirror containing unavail OST */
                if (lo->ldo_mirrors[index].lme_primary && second_pick < 0)
                        second_pick = index;

                /* 3rd pick is for non-primary mirror containing unavail OST */
                if (second_pick < 0 && third_pick < 0)
                        third_pick = index;

                /**
                 * we found a non-primary 1st pick, we'd like to find a
                 * potential pirmary mirror.
                 */
                if (picked >= 0 && !lo->ldo_mirrors[index].lme_primary)
                        continue;

                /* check the availability of OSTs */
                lod_foreach_mirror_comp(lod_comp, lo, index) {
                        if (!lod_comp_inited(lod_comp) || !lod_comp->llc_stripe)
                                continue;

                        for (j = 0; j < lod_comp->llc_stripe_count; j++) {
                                struct dt_object *dt = lod_comp->llc_stripe[j];

                                rc = lod_check_ost_avail(env, lo, dt, index);
                                if (rc < 0)
                                        RETURN(rc);

                                ost_avail = !!rc;
                                if (!ost_avail)
                                        break;
                        } /* for all dt object in one component */
                        if (!ost_avail)
                                break;
                } /* for all components in a mirror */

                /**
                 * the OSTs where allocated objects locates in the components
                 * of the mirror are available.
                 */
                if (!ost_avail)
                        continue;

                /* this mirror has all OSTs available */
                picked = index;

                /**
                 * primary with all OSTs are available, this is the perfect
                 * 1st pick.
                 */
                if (lo->ldo_mirrors[index].lme_primary)
                        break;
        } /* for all mirrors */

        /* failed to pick a sound mirror, lower our expectation */
        if (picked < 0)
                picked = second_pick;
        if (picked < 0)
                picked = third_pick;
        if (picked < 0)
                RETURN(-ENODATA);

        RETURN(picked);
}

static int lod_prepare_resync_mirror(const struct lu_env *env,
                                     struct lod_object *lo,
                                     __u16 mirror_id)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_layout_component *lod_comp;
        bool neg = !!(MIRROR_ID_NEG & mirror_id);
        int i;

        mirror_id &= ~MIRROR_ID_NEG;

        for (i = 0; i < lo->ldo_mirror_count; i++) {
                if ((!neg && lo->ldo_mirrors[i].lme_id != mirror_id) ||
                    (neg && lo->ldo_mirrors[i].lme_id == mirror_id))
                        continue;

                lod_foreach_mirror_comp(lod_comp, lo, i) {
                        if (lod_comp_inited(lod_comp))
                                continue;

                        info->lti_comp_idx[info->lti_count++] =
                                lod_comp_index(lo, lod_comp);
                }
        }

        return 0;
}

/**
 * figure out the components should be instantiated for resync.
 */
static int lod_prepare_resync(const struct lu_env *env, struct lod_object *lo,
                              struct lu_extent *extent)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lod_layout_component *lod_comp;
        unsigned int need_sync = 0;
        int i;

        CDEBUG(D_LAYOUT,
               DFID": instantiate all stale components in "DEXT"\n",
               PFID(lod_object_fid(lo)), PEXT(extent));

        /**
         * instantiate all components within this extent, even non-stale
         * components.
         */
        for (i = 0; i < lo->ldo_mirror_count; i++) {
                if (!lo->ldo_mirrors[i].lme_stale)
                        continue;

                lod_foreach_mirror_comp(lod_comp, lo, i) {
                        if (!lu_extent_is_overlapped(extent,
                                                &lod_comp->llc_extent))
                                break;

                        need_sync++;

                        if (lod_comp_inited(lod_comp))
                                continue;

                        CDEBUG(D_LAYOUT, "resync instantiate %d / %d\n",
                               i, lod_comp_index(lo, lod_comp));
                        info->lti_comp_idx[info->lti_count++] =
                                        lod_comp_index(lo, lod_comp);
                }
        }

        return need_sync ? 0 : -EALREADY;
}

static int lod_declare_update_rdonly(const struct lu_env *env,
                struct lod_object *lo, struct md_layout_change *mlc,
                struct thandle *th)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lu_attr *layout_attr = &info->lti_layout_attr;
        struct lod_layout_component *lod_comp;
        struct lu_extent extent = { 0 };
        int rc;
        ENTRY;

        LASSERT(lo->ldo_flr_state == LCM_FL_RDONLY);
        LASSERT(mlc->mlc_opc == MD_LAYOUT_WRITE ||
                mlc->mlc_opc == MD_LAYOUT_RESYNC);
        LASSERT(lo->ldo_mirror_count > 0);

        if (mlc->mlc_opc == MD_LAYOUT_WRITE) {
                struct layout_intent *layout = mlc->mlc_intent;
                int write = layout->li_opc == LAYOUT_INTENT_WRITE;
                int picked;

                extent = layout->li_extent;
                CDEBUG(D_LAYOUT, DFID": trying to write :"DEXT"\n",
                       PFID(lod_object_fid(lo)), PEXT(&extent));

                picked = lod_primary_pick(env, lo, &extent);
                if (picked < 0)
                        RETURN(picked);

                CDEBUG(D_LAYOUT, DFID": picked mirror id %u as primary\n",
                       PFID(lod_object_fid(lo)),
                       lo->ldo_mirrors[picked].lme_id);

                /* Update extents of primary before staling */
                rc = lod_declare_update_extents(env, lo, &extent, th, picked,
                                                write);
                if (rc < 0)
                        GOTO(out, rc);

                if (layout->li_opc == LAYOUT_INTENT_TRUNC) {
                        /**
                         * trunc transfers [0, size) in the intent extent, we'd
                         * stale components overlapping [size, eof).
                         */
                        extent.e_start = extent.e_end;
                        extent.e_end = OBD_OBJECT_EOF;
                }

                /* stale overlapping components from other mirrors */
                rc = lod_stale_components(env, lo, picked, &extent, th);
                if (rc < 0)
                        GOTO(out, rc);

                /* restore truncate intent extent */
                if (layout->li_opc == LAYOUT_INTENT_TRUNC)
                        extent.e_end = extent.e_start;

                /* instantiate components for the picked mirror, start from 0 */
                extent.e_start = 0;

                lod_foreach_mirror_comp(lod_comp, lo, picked) {
                        if (!lu_extent_is_overlapped(&extent,
                                                     &lod_comp->llc_extent))
                                break;

                        if (!lod_is_instantiation_needed(lod_comp))
                                continue;

                        info->lti_comp_idx[info->lti_count++] =
                                                lod_comp_index(lo, lod_comp);
                }

                lo->ldo_flr_state = LCM_FL_WRITE_PENDING;
        } else { /* MD_LAYOUT_RESYNC */
                int i;

                /**
                 * could contain multiple non-stale mirrors, so we need to
                 * prep uninited all components assuming any non-stale mirror
                 * could be picked as the primary mirror.
                 */
                if (mlc->mlc_mirror_id == 0) {
                        /* normal resync */
                        for (i = 0; i < lo->ldo_mirror_count; i++) {
                                if (lo->ldo_mirrors[i].lme_stale)
                                        continue;

                                lod_foreach_mirror_comp(lod_comp, lo, i) {
                                        if (!lod_comp_inited(lod_comp))
                                                break;

                                        if (extent.e_end <
                                                lod_comp->llc_extent.e_end)
                                                extent.e_end =
                                                     lod_comp->llc_extent.e_end;
                                }
                        }
                        rc = lod_prepare_resync(env, lo, &extent);
                        if (rc)
                                GOTO(out, rc);
                } else {
                        /* mirror write, try to init its all components */
                        rc = lod_prepare_resync_mirror(env, lo,
                                                       mlc->mlc_mirror_id);
                        if (rc)
                                GOTO(out, rc);
                }

                /* change the file state to SYNC_PENDING */
                lo->ldo_flr_state = LCM_FL_SYNC_PENDING;
        }

        /* Reset the layout version once it's becoming too large.
         * This way it can make sure that the layout version is
         * monotonously increased in this writing era. */
        lod_obj_inc_layout_gen(lo);
        if (lo->ldo_layout_gen > (LCME_ID_MAX >> 1)) {
                __u32 layout_version;

                get_random_bytes(&layout_version, sizeof(layout_version));
                lo->ldo_layout_gen = layout_version & 0xffff;
        }

        rc = lod_declare_instantiate_components(env, lo, th);
        if (rc)
                GOTO(out, rc);

        layout_attr->la_valid = LA_LAYOUT_VERSION;
        layout_attr->la_layout_version = 0; /* set current version */
        if (mlc->mlc_opc == MD_LAYOUT_RESYNC)
                layout_attr->la_layout_version = LU_LAYOUT_RESYNC;
        rc = lod_declare_attr_set(env, &lo->ldo_obj, layout_attr, th);
        if (rc)
                GOTO(out, rc);

out:
        if (rc)
                lod_striping_free(env, lo);
        RETURN(rc);
}

static int lod_declare_update_write_pending(const struct lu_env *env,
                struct lod_object *lo, struct md_layout_change *mlc,
                struct thandle *th)
{
        struct lod_thread_info *info = lod_env_info(env);
        struct lu_attr *layout_attr = &info->lti_layout_attr;
        struct lod_layout_component *lod_comp;
        struct lu_extent extent = { 0 };
        int primary = -1;
        int i;
        int rc;
        ENTRY;

        LASSERT(lo->ldo_flr_state == LCM_FL_WRITE_PENDING);
        LASSERT(mlc->mlc_opc == MD_LAYOUT_WRITE ||
                mlc->mlc_opc == MD_LAYOUT_RESYNC);

        /* look for the primary mirror */
        for (i = 0; i < lo->ldo_mirror_count; i++) {
                if (lo->ldo_mirrors[i].lme_stale)
                        continue;

                LASSERTF(primary < 0, DFID " has multiple primary: %u / %u",
                         PFID(lod_object_fid(lo)),
                         lo->ldo_mirrors[i].lme_id,
                         lo->ldo_mirrors[primary].lme_id);

                primary = i;
        }
        if (primary < 0) {
                CERROR(DFID ": doesn't have a primary mirror\n",
                       PFID(lod_object_fid(lo)));
                GOTO(out, rc = -ENODATA);
        }

        CDEBUG(D_LAYOUT, DFID": found primary %u\n",
               PFID(lod_object_fid(lo)), lo->ldo_mirrors[primary].lme_id);

        LASSERT(!lo->ldo_mirrors[primary].lme_stale);

        /* for LAYOUT_WRITE opc, it has to do the following operations:
         * 1. stale overlapping componets from stale mirrors;
         * 2. instantiate components of the primary mirror;
         * 3. transfter layout version to all objects of the primary;
         *
         * for LAYOUT_RESYNC opc, it will do:
         * 1. instantiate components of all stale mirrors;
         * 2. transfer layout version to all objects to close write era. */

        if (mlc->mlc_opc == MD_LAYOUT_WRITE) {
                struct layout_intent *layout = mlc->mlc_intent;
                int write = layout->li_opc == LAYOUT_INTENT_WRITE;

                LASSERT(mlc->mlc_intent != NULL);

                extent = mlc->mlc_intent->li_extent;

                CDEBUG(D_LAYOUT, DFID": intent to write: "DEXT"\n",
                       PFID(lod_object_fid(lo)), PEXT(&extent));

                /* 1. Update extents of primary before staling */
                rc = lod_declare_update_extents(env, lo, &extent, th, primary,
                                                write);
                if (rc < 0)
                        GOTO(out, rc);

                if (mlc->mlc_intent->li_opc == LAYOUT_INTENT_TRUNC) {
                        /**
                         * trunc transfers [0, size) in the intent extent, we'd
                         * stale components overlapping [size, eof).
                         */
                        extent.e_start = extent.e_end;
                        extent.e_end = OBD_OBJECT_EOF;
                }

                /* 2. stale overlapping components */
                rc = lod_stale_components(env, lo, primary, &extent, th);
                if (rc < 0)
                        GOTO(out, rc);

                /* 3. find the components which need instantiating.
                 * instantiate [0, mlc->mlc_intent->e_end) */

                /* restore truncate intent extent */
                if (mlc->mlc_intent->li_opc == LAYOUT_INTENT_TRUNC)
                        extent.e_end = extent.e_start;
                extent.e_start = 0;

                lod_foreach_mirror_comp(lod_comp, lo, primary) {
                        if (!lu_extent_is_overlapped(&extent,
                                                     &lod_comp->llc_extent))
                                break;

                        if (!lod_is_instantiation_needed(lod_comp))
                                continue;

                        CDEBUG(D_LAYOUT, "write instantiate %d / %d\n",
                               primary, lod_comp_index(lo, lod_comp));
                        info->lti_comp_idx[info->lti_count++] =
                                                lod_comp_index(lo, lod_comp);
                }
        } else { /* MD_LAYOUT_RESYNC */
                if (mlc->mlc_mirror_id == 0) {
                        /* normal resync */
                        lod_foreach_mirror_comp(lod_comp, lo, primary) {
                                if (!lod_comp_inited(lod_comp))
                                        break;

                                extent.e_end = lod_comp->llc_extent.e_end;
                        }

                        rc = lod_prepare_resync(env, lo, &extent);
                        if (rc)
                                GOTO(out, rc);
                } else {
                        /* mirror write, try to init its all components */
                        rc = lod_prepare_resync_mirror(env, lo,
                                                       mlc->mlc_mirror_id);
                        if (rc)
                                GOTO(out, rc);
                }

                /* change the file state to SYNC_PENDING */
                lo->ldo_flr_state = LCM_FL_SYNC_PENDING;
        }

        rc = lod_declare_instantiate_components(env, lo, th);
        if (rc)
                GOTO(out, rc);

        /* 3. transfer layout version to OST objects.
         * transfer new layout version to OST objects so that stale writes
         * can be denied. It also ends an era of writing by setting
         * LU_LAYOUT_RESYNC. Normal client can never use this bit to
         * send write RPC; only resync RPCs could do it. */
        layout_attr->la_valid = LA_LAYOUT_VERSION;
        layout_attr->la_layout_version = 0; /* set current version */
        if (mlc->mlc_opc == MD_LAYOUT_RESYNC)
                layout_attr->la_layout_version = LU_LAYOUT_RESYNC;
        rc = lod_declare_attr_set(env, &lo->ldo_obj, layout_attr, th);
        if (rc)
                GOTO(out, rc);

        lod_obj_inc_layout_gen(lo);
out:
        if (rc)
                lod_striping_free(env, lo);
        RETURN(rc);
}

static int lod_declare_update_sync_pending(const struct lu_env *env,
                struct lod_object *lo, struct md_layout_change *mlc,
                struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        unsigned sync_components = 0;
        unsigned resync_components = 0;
        int i;
        int rc;
        ENTRY;

        LASSERT(lo->ldo_flr_state == LCM_FL_SYNC_PENDING);
        LASSERT(mlc->mlc_opc == MD_LAYOUT_RESYNC_DONE ||
                mlc->mlc_opc == MD_LAYOUT_WRITE);

        CDEBUG(D_LAYOUT, DFID ": received op %d in sync pending\n",
               PFID(lod_object_fid(lo)), mlc->mlc_opc);

        if (mlc->mlc_opc == MD_LAYOUT_WRITE) {
                CDEBUG(D_LAYOUT, DFID": cocurrent write to sync pending\n",
                       PFID(lod_object_fid(lo)));

                lo->ldo_flr_state = LCM_FL_WRITE_PENDING;
                return lod_declare_update_write_pending(env, lo, mlc, th);
        }

        /* MD_LAYOUT_RESYNC_DONE */

        for (i = 0; i < lo->ldo_comp_cnt; i++) {
                struct lod_layout_component *lod_comp;
                int j;

                lod_comp = &lo->ldo_comp_entries[i];

                if (!(lod_comp->llc_flags & LCME_FL_STALE)) {
                        sync_components++;
                        continue;
                }

                for (j = 0; j < mlc->mlc_resync_count; j++) {
                        if (lod_comp->llc_id != mlc->mlc_resync_ids[j])
                                continue;

                        mlc->mlc_resync_ids[j] = LCME_ID_INVAL;
                        lod_comp->llc_flags &= ~LCME_FL_STALE;
                        resync_components++;
                        break;
                }
        }

        /* valid check */
        for (i = 0; i < mlc->mlc_resync_count; i++) {
                if (mlc->mlc_resync_ids[i] == LCME_ID_INVAL)
                        continue;

                CDEBUG(D_LAYOUT, DFID": lcme id %u (%d / %zd) not exist "
                       "or already synced\n", PFID(lod_object_fid(lo)),
                       mlc->mlc_resync_ids[i], i, mlc->mlc_resync_count);
                GOTO(out, rc = -EINVAL);
        }

        if (!sync_components || (mlc->mlc_resync_count && !resync_components)) {
                CDEBUG(D_LAYOUT, DFID": no mirror in sync\n",
                       PFID(lod_object_fid(lo)));

                /* tend to return an error code here to prevent
                 * the MDT from setting SoM attribute */
                GOTO(out, rc = -EINVAL);
        }

        CDEBUG(D_LAYOUT, DFID": synced %u resynced %u/%zu components\n",
               PFID(lod_object_fid(lo)),
               sync_components, resync_components, mlc->mlc_resync_count);

        lo->ldo_flr_state = LCM_FL_RDONLY;
        lod_obj_inc_layout_gen(lo);

        info->lti_buf.lb_len = lod_comp_md_size(lo, false);
        rc = lod_sub_declare_xattr_set(env, lod_object_child(lo),
                                       &info->lti_buf, XATTR_NAME_LOV, 0, th);
        EXIT;

out:
        if (rc)
                lod_striping_free(env, lo);
        RETURN(rc);
}

static int lod_declare_layout_change(const struct lu_env *env,
                struct dt_object *dt, struct md_layout_change *mlc,
                struct thandle *th)
{
        struct lod_thread_info  *info = lod_env_info(env);
        struct lod_object *lo = lod_dt_obj(dt);
        int rc;
        ENTRY;

        if (!S_ISREG(dt->do_lu.lo_header->loh_attr) || !dt_object_exists(dt) ||
            dt_object_remote(dt_object_child(dt)))
                RETURN(-EINVAL);

        rc = lod_striping_load(env, lo);
        if (rc)
                GOTO(out, rc);

        LASSERT(lo->ldo_comp_cnt > 0);

        rc = lod_layout_data_init(info, lo->ldo_comp_cnt);
        if (rc)
                GOTO(out, rc);

        switch (lo->ldo_flr_state) {
        case LCM_FL_NONE:
                rc = lod_declare_update_plain(env, lo, mlc->mlc_intent,
                                              &mlc->mlc_buf, th);
                break;
        case LCM_FL_RDONLY:
                rc = lod_declare_update_rdonly(env, lo, mlc, th);
                break;
        case LCM_FL_WRITE_PENDING:
                rc = lod_declare_update_write_pending(env, lo, mlc, th);
                break;
        case LCM_FL_SYNC_PENDING:
                rc = lod_declare_update_sync_pending(env, lo, mlc, th);
                break;
        default:
                rc = -ENOTSUPP;
                break;
        }
out:
        RETURN(rc);
}

/**
 * Instantiate layout component objects which covers the intent write offset.
 */
static int lod_layout_change(const struct lu_env *env, struct dt_object *dt,
                             struct md_layout_change *mlc, struct thandle *th)
{
        struct lu_attr *attr = &lod_env_info(env)->lti_attr;
        struct lu_attr *layout_attr = &lod_env_info(env)->lti_layout_attr;
        struct lod_object *lo = lod_dt_obj(dt);
        int rc;

        rc = lod_striped_create(env, dt, attr, NULL, th);
        if (!rc && layout_attr->la_valid & LA_LAYOUT_VERSION) {
                layout_attr->la_layout_version |= lo->ldo_layout_gen;
                rc = lod_attr_set(env, dt, layout_attr, th);
        }

        return rc;
}

struct dt_object_operations lod_obj_ops = {
        .do_read_lock           = lod_read_lock,
        .do_write_lock          = lod_write_lock,
        .do_read_unlock         = lod_read_unlock,
        .do_write_unlock        = lod_write_unlock,
        .do_write_locked        = lod_write_locked,
        .do_attr_get            = lod_attr_get,
        .do_declare_attr_set    = lod_declare_attr_set,
        .do_attr_set            = lod_attr_set,
        .do_xattr_get           = lod_xattr_get,
        .do_declare_xattr_set   = lod_declare_xattr_set,
        .do_xattr_set           = lod_xattr_set,
        .do_declare_xattr_del   = lod_declare_xattr_del,
        .do_xattr_del           = lod_xattr_del,
        .do_xattr_list          = lod_xattr_list,
        .do_ah_init             = lod_ah_init,
        .do_declare_create      = lod_declare_create,
        .do_create              = lod_create,
        .do_declare_destroy     = lod_declare_destroy,
        .do_destroy             = lod_destroy,
        .do_index_try           = lod_index_try,
        .do_declare_ref_add     = lod_declare_ref_add,
        .do_ref_add             = lod_ref_add,
        .do_declare_ref_del     = lod_declare_ref_del,
        .do_ref_del             = lod_ref_del,
        .do_object_sync         = lod_object_sync,
        .do_object_lock         = lod_object_lock,
        .do_object_unlock       = lod_object_unlock,
        .do_invalidate          = lod_invalidate,
        .do_declare_layout_change = lod_declare_layout_change,
        .do_layout_change       = lod_layout_change,
};

/**
 * Implementation of dt_body_operations::dbo_read.
 *
 * \see dt_body_operations::dbo_read() in the API description for details.
 */
static ssize_t lod_read(const struct lu_env *env, struct dt_object *dt,
                        struct lu_buf *buf, loff_t *pos)
{
        struct dt_object *next = dt_object_child(dt);

        LASSERT(S_ISREG(dt->do_lu.lo_header->loh_attr) ||
                S_ISLNK(dt->do_lu.lo_header->loh_attr));
        return next->do_body_ops->dbo_read(env, next, buf, pos);
}

/**
 * Implementation of dt_body_operations::dbo_declare_write.
 *
 * \see dt_body_operations::dbo_declare_write() in the API description
 * for details.
 */
static ssize_t lod_declare_write(const struct lu_env *env,
                                 struct dt_object *dt,
                                 const struct lu_buf *buf, loff_t pos,
                                 struct thandle *th)
{
        return lod_sub_declare_write(env, dt_object_child(dt), buf, pos, th);
}

/**
 * Implementation of dt_body_operations::dbo_write.
 *
 * \see dt_body_operations::dbo_write() in the API description for details.
 */
static ssize_t lod_write(const struct lu_env *env, struct dt_object *dt,
                         const struct lu_buf *buf, loff_t *pos,
                         struct thandle *th)
{
        LASSERT(S_ISREG(dt->do_lu.lo_header->loh_attr) ||
                S_ISLNK(dt->do_lu.lo_header->loh_attr));
        return lod_sub_write(env, dt_object_child(dt), buf, pos, th);
}

static int lod_declare_punch(const struct lu_env *env, struct dt_object *dt,
                             __u64 start, __u64 end, struct thandle *th)
{
        if (dt_object_remote(dt))
                return -ENOTSUPP;

        return lod_sub_declare_punch(env, dt_object_child(dt), start, end, th);
}

static int lod_punch(const struct lu_env *env, struct dt_object *dt,
                     __u64 start, __u64 end, struct thandle *th)
{
        if (dt_object_remote(dt))
                return -ENOTSUPP;

        LASSERT(S_ISREG(dt->do_lu.lo_header->loh_attr));
        return lod_sub_punch(env, dt_object_child(dt), start, end, th);
}

/*
 * different type of files use the same body_ops because object may be created
 * in OUT, where there is no chance to set correct body_ops for each type, so
 * body_ops themselves will check file type inside, see lod_read/write/punch for
 * details.
 */
const struct dt_body_operations lod_body_ops = {
        .dbo_read               = lod_read,
        .dbo_declare_write      = lod_declare_write,
        .dbo_write              = lod_write,
        .dbo_declare_punch      = lod_declare_punch,
        .dbo_punch              = lod_punch,
};

/**
 * Implementation of lu_object_operations::loo_object_init.
 *
 * The function determines the type and the index of the target device using
 * sequence of the object's FID. Then passes control down to the
 * corresponding device:
 *  OSD for the local objects, OSP for remote
 *
 * \see lu_object_operations::loo_object_init() in the API description
 * for details.
 */
static int lod_object_init(const struct lu_env *env, struct lu_object *lo,
                           const struct lu_object_conf *conf)
{
        struct lod_device       *lod    = lu2lod_dev(lo->lo_dev);
        struct lu_device        *cdev   = NULL;
        struct lu_object        *cobj;
        struct lod_tgt_descs    *ltd    = NULL;
        struct lod_tgt_desc     *tgt;
        u32                      idx    = 0;
        int                      type   = LU_SEQ_RANGE_ANY;
        int                      rc;
        ENTRY;

        rc = lod_fld_lookup(env, lod, lu_object_fid(lo), &idx, &type);
        if (rc != 0) {
                /* Note: Sometimes, it will Return EAGAIN here, see
                 * ptrlpc_import_delay_req(), which might confuse
                 * lu_object_find_at() and make it wait there incorrectly.
                 * so we convert it to EIO here.*/
                if (rc == -EAGAIN)
                        rc = -EIO;

                RETURN(rc);
        }

        if (type == LU_SEQ_RANGE_MDT &&
            idx == lu_site2seq(lo->lo_dev->ld_site)->ss_node_id) {
                cdev = &lod->lod_child->dd_lu_dev;
        } else if (type == LU_SEQ_RANGE_MDT) {
                ltd = &lod->lod_mdt_descs;
                lod_getref(ltd);
        } else if (type == LU_SEQ_RANGE_OST) {
                ltd = &lod->lod_ost_descs;
                lod_getref(ltd);
        } else {
                LBUG();
        }

        if (ltd != NULL) {
                if (ltd->ltd_tgts_size > idx &&
                    cfs_bitmap_check(ltd->ltd_tgt_bitmap, idx)) {
                        tgt = LTD_TGT(ltd, idx);

                        LASSERT(tgt != NULL);
                        LASSERT(tgt->ltd_tgt != NULL);

                        cdev = &(tgt->ltd_tgt->dd_lu_dev);
                }
                lod_putref(lod, ltd);
        }

        if (unlikely(cdev == NULL))
                RETURN(-ENOENT);

        cobj = cdev->ld_ops->ldo_object_alloc(env, lo->lo_header, cdev);
        if (unlikely(cobj == NULL))
                RETURN(-ENOMEM);

        lu2lod_obj(lo)->ldo_obj.do_body_ops = &lod_body_ops;

        lu_object_add(lo, cobj);

        RETURN(0);
}

/**
 *
 * Alloc cached foreign LOV
 *
 * \param[in] lo        object
 * \param[in] size      size of foreign LOV
 *
 * \retval              0 on success
 * \retval              negative if failed
 */
int lod_alloc_foreign_lov(struct lod_object *lo, size_t size)
{
        OBD_ALLOC_LARGE(lo->ldo_foreign_lov, size);
        if (lo->ldo_foreign_lov == NULL)
                return -ENOMEM;
        lo->ldo_foreign_lov_size = size;
        lo->ldo_is_foreign = 1;
        return 0;
}

/**
 *
 * Free cached foreign LOV
 *
 * \param[in] lo        object
 */
void lod_free_foreign_lov(struct lod_object *lo)
{
        if (lo->ldo_foreign_lov != NULL)
                OBD_FREE_LARGE(lo->ldo_foreign_lov, lo->ldo_foreign_lov_size);
        lo->ldo_foreign_lov = NULL;
        lo->ldo_foreign_lov_size = 0;
        lo->ldo_is_foreign = 0;
}

/**
 *
 * Free cached foreign LMV
 *
 * \param[in] lo        object
 */
void lod_free_foreign_lmv(struct lod_object *lo)
{
        if (lo->ldo_foreign_lmv != NULL)
                OBD_FREE_LARGE(lo->ldo_foreign_lmv, lo->ldo_foreign_lmv_size);
        lo->ldo_foreign_lmv = NULL;
        lo->ldo_foreign_lmv_size = 0;
        lo->ldo_dir_is_foreign = 0;
}

/**
 *
 * Release resources associated with striping.
 *
 * If the object is striped (regular or directory), then release
 * the stripe objects references and free the ldo_stripe array.
 *
 * \param[in] env       execution environment
 * \param[in] lo        object
 */
void lod_striping_free_nolock(const struct lu_env *env, struct lod_object *lo)
{
        struct lod_layout_component *lod_comp;
        int i, j;

        if (unlikely(lo->ldo_is_foreign)) {
                lod_free_foreign_lov(lo);
                lo->ldo_comp_cached = 0;
        } else if (unlikely(lo->ldo_dir_is_foreign)) {
                lod_free_foreign_lmv(lo);
                lo->ldo_dir_stripe_loaded = 0;
        } else if (lo->ldo_stripe != NULL) {
                LASSERT(lo->ldo_comp_entries == NULL);
                LASSERT(lo->ldo_dir_stripes_allocated > 0);

                for (i = 0; i < lo->ldo_dir_stripe_count; i++) {
                        if (lo->ldo_stripe[i])
                                dt_object_put(env, lo->ldo_stripe[i]);
                }

                j = sizeof(struct dt_object *) * lo->ldo_dir_stripes_allocated;
                OBD_FREE(lo->ldo_stripe, j);
                lo->ldo_stripe = NULL;
                lo->ldo_dir_stripes_allocated = 0;
                lo->ldo_dir_stripe_loaded = 0;
                lo->ldo_dir_stripe_count = 0;
        } else if (lo->ldo_comp_entries != NULL) {
                for (i = 0; i < lo->ldo_comp_cnt; i++) {
                        /* free lod_layout_component::llc_stripe array */
                        lod_comp = &lo->ldo_comp_entries[i];

                        if (lod_comp->llc_stripe == NULL)
                                continue;
                        LASSERT(lod_comp->llc_stripes_allocated != 0);
                        for (j = 0; j < lod_comp->llc_stripes_allocated; j++) {
                                if (lod_comp->llc_stripe[j] != NULL)
                                        lu_object_put(env,
                                               &lod_comp->llc_stripe[j]->do_lu);
                        }
                        OBD_FREE(lod_comp->llc_stripe,
                                 sizeof(struct dt_object *) *
                                 lod_comp->llc_stripes_allocated);
                        lod_comp->llc_stripe = NULL;
                        OBD_FREE(lod_comp->llc_ost_indices,
                                 sizeof(__u32) *
                                 lod_comp->llc_stripes_allocated);
                        lod_comp->llc_ost_indices = NULL;
                        lod_comp->llc_stripes_allocated = 0;
                }
                lod_free_comp_entries(lo);
                lo->ldo_comp_cached = 0;
        }
}

void lod_striping_free(const struct lu_env *env, struct lod_object *lo)
{
        mutex_lock(&lo->ldo_layout_mutex);
        lod_striping_free_nolock(env, lo);
        mutex_unlock(&lo->ldo_layout_mutex);
}

/**
 * Implementation of lu_object_operations::loo_object_free.
 *
 * \see lu_object_operations::loo_object_free() in the API description
 * for details.
 */
static void lod_object_free(const struct lu_env *env, struct lu_object *o)
{
        struct lod_object *lo = lu2lod_obj(o);

        /* release all underlying object pinned */
        lod_striping_free(env, lo);
        lu_object_fini(o);
        OBD_SLAB_FREE_PTR(lo, lod_object_kmem);
}

/**
 * Implementation of lu_object_operations::loo_object_release.
 *
 * \see lu_object_operations::loo_object_release() in the API description
 * for details.
 */
static void lod_object_release(const struct lu_env *env, struct lu_object *o)
{
        /* XXX: shouldn't we release everything here in case if object
         * creation failed before? */
}

/**
 * Implementation of lu_object_operations::loo_object_print.
 *
 * \see lu_object_operations::loo_object_print() in the API description
 * for details.
 */
static int lod_object_print(const struct lu_env *env, void *cookie,
                            lu_printer_t p, const struct lu_object *l)
{
        struct lod_object *o = lu2lod_obj((struct lu_object *) l);

        return (*p)(env, cookie, LUSTRE_LOD_NAME"-object@%p", o);
}

struct lu_object_operations lod_lu_obj_ops = {
        .loo_object_init        = lod_object_init,
        .loo_object_free        = lod_object_free,
        .loo_object_release     = lod_object_release,
        .loo_object_print       = lod_object_print,
};