LU-9771 flr: instantiate component for truncate

[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, 2016, 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 <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, int ign)
{
        return lod_sub_insert(env, dt_object_child(dt), rec, key, th, ign);
}

/**
 * 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;
        ENTRY;

        LASSERT(lo->ldo_dir_stripe_count > 0);
        next = lo->ldo_stripe[0];
        LASSERT(next != NULL);
        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 = 0;
        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];
                LASSERT(next != NULL);
                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;
        ENTRY;

        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.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;

        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;
        int                     rc;
        ENTRY;

        LOD_CHECK_STRIPED_IT(env, it, lo);

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

        /* go to next stripe */
        if (it->lit_stripe_index + 1 >= lo->ldo_dir_stripe_count)
                RETURN(1);

        it->lit_stripe_index++;

        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;

        next = lo->ldo_stripe[it->lit_stripe_index];
        LASSERT(next != NULL);
        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)) {
                it->lit_it = it_next;
                goto again;
        } else {
                rc = PTR_ERR(it_next);
        }

        RETURN(rc);
}

/**
 * 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 it is not a striped directory, then load nothing. */
        if (magic != LMV_MAGIC_V1)
                RETURN(0);

        /* If it is in migration (or failure), then load nothing. */
        if (le32_to_cpu(lmv1->lmv_hash_type) & LMV_HASH_FLAG_MIGRATION)
                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_load_striping_locked(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 (dt_object_exists(lo->ldo_stripe[i]) == 0)
                                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);
}

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;

                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_load_striping(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;
                        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_load_striping_locked(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) {
                        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)
                        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;
                int                      rc1 = 0;

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

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

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

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

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

        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;
        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);
        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;

        if (le32_to_cpu(lmv1->lmv_hash_type) & LMV_HASH_FLAG_MIGRATION)
                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))
                        GOTO(out, rc = -ESTALE);

                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_object_free_striping(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;

                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_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;
        ENTRY;

        /* The lum has been verifed in lod_verify_md_striping */
        LASSERT(le32_to_cpu(lum->lum_magic) == LMV_USER_MAGIC);
        LASSERT(le32_to_cpu(lum->lum_stripe_count) > 0);

        stripe_count = le32_to_cpu(lum->lum_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;
        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(!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, 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 (i < stripe_count - 1)
                        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));
                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_stripe_loaded = 1;
        lo->ldo_dir_striped = 1;
        lo->ldo_stripe = stripe;
        lo->ldo_dir_stripe_count = i;
        lo->ldo_dir_stripes_allocated = stripe_count;

        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);
}

/**
 * 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 lod_device       *lod = lu2lod_dev(dt->do_lu.lo_dev);
        struct lmv_user_md_v1   *lum;
        int                     rc;
        ENTRY;

        lum = lum_buf->lb_buf;
        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 (le32_to_cpu(lum->lum_stripe_count) == 0)
                GOTO(out, rc = 0);

        rc = lod_verify_md_striping(lod, lum);
        if (rc != 0)
                GOTO(out, rc);

        /* 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_object_free_striping(env, lo);
                GOTO(out, rc);
        }
out:
        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_load_striping(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++) {
                LASSERT(lo->ldo_stripe[i]);

                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 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 == -ENODATA)
                return 0;

        if (rc < 0)
                return rc;

        ff->ff_parent = *lu_object_fid(&lo->ldo_obj.do_lu);
        ff->ff_parent.f_ver = stripe_idx;
        fid_cpu_to_le(&ff->ff_parent, &ff->ff_parent);
        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,
                                  struct thandle *th, bool declare)
{
        struct lod_object *lo = lod_dt_obj(dt);
        struct lod_thread_info  *info = lod_env_info(env);
        struct lu_buf *buf = &info->lti_buf;
        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_load_striping(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);
        }

        buf->lb_buf = info->lti_ea_store;
        buf->lb_len = info->lti_ea_store_size;

        data.locd_declare = declare;
        data.locd_stripe_cb = lod_obj_stripe_replace_parent_fid_cb;
        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);
}

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;

        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;
        }


        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_NOT_FLR)
                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;
                if (!lod_comp->llc_stripe_count ||
                    lod_comp->llc_stripe_count == (__u16)-1)
                        lod_comp->llc_stripe_count =
                                desc->ld_default_stripe_count;
                lod_comp->llc_stripe_size = v1->lmm_stripe_size;
                if (!lod_comp->llc_stripe_size)
                        lod_comp->llc_stripe_size =
                                desc->ld_default_stripe_size;

                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, id;
        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++) {
                id = comp_v1->lcm_entries[i].lcme_id;

                for (j = 0; j < lo->ldo_comp_cnt; j++) {
                        lod_comp = &lo->ldo_comp_entries[j];
                        if (id == lod_comp->llc_id || id == LCME_ID_ALL) {
                                lod_comp->llc_flags =
                                        comp_v1->lcm_entries[i].lcme_flags;
                                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, &info->lti_buf,
                                       XATTR_NAME_LOV, 0, 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_NOT_FLR)
                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 (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);
        struct dt_object *next = dt_object_child(&lo->ldo_obj);
        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++;

        dt_write_lock(env, next, 0);
        rc = lod_load_striping_locked(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_object_free_striping(env, lo);
        dt_write_unlock(env, next);

        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;
        if (le32_to_cpu(cur_lcm->lcm_magic) != LOV_MAGIC_COMP_V1)
                RETURN(-EINVAL);

        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) {
                        /* new mirrored file, create new mirror ID */
                        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_NOT_FLR)
                lcm->lcm_flags = cpu_to_le32(LCM_FL_RDONLY);

        LASSERT(dt_write_locked(env, dt_object_child(dt)));
        lod_object_free_striping(env, lo);
        rc = lod_parse_striping(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);
}

/**
 * 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)) &&
            (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 (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 (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, 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++) {
                LASSERT(lo->ldo_stripe[i]);

                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_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:
                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_OTHER, "set default stripe_count # %u stripe_offset %d\n",
              le32_to_cpu(lum->lum_stripe_count),
              (int)le32_to_cpu(lum->lum_stripe_offset));

        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) {
                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)
                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;
                char             *stripe_name = info->lti_key;
                struct lu_name          *sname;
                struct linkea_data       ldata          = { NULL };
                struct lu_buf            linkea_buf;

                dto = lo->ldo_stripe[i];

                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, 0);
                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, 0);
                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_ke