/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
 * vim:expandtab:shiftwidth=8:tabstop=8:
 *
 * 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 LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011 Whamcloud, Inc.
 *
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */

#define DEBUG_SUBSYSTEM S_ECHO
#ifdef __KERNEL__
#include <libcfs/libcfs.h>
#else
#include <liblustre.h>
#endif

#include <obd.h>
#include <obd_support.h>
#include <obd_class.h>
#include <lustre_debug.h>
#include <lprocfs_status.h>
#include <cl_object.h>

#include "echo_internal.h"

/** \defgroup echo_client Echo Client
 * @{
 */

struct echo_device {
        struct cl_device        ed_cl;
        struct echo_client_obd *ed_ec;

        struct cl_site          ed_site_myself;
        struct cl_site         *ed_site;
        struct lu_device       *ed_next;
        int                     ed_next_islov;
};

struct echo_object {
        struct cl_object        eo_cl;
        struct cl_object_header eo_hdr;

        struct echo_device     *eo_dev;
        cfs_list_t              eo_obj_chain;
        struct lov_stripe_md   *eo_lsm;
        cfs_atomic_t            eo_npages;
        int                     eo_deleted;
};

struct echo_object_conf {
        struct cl_object_conf  eoc_cl;
        struct lov_stripe_md **eoc_md;
};

struct echo_page {
        struct cl_page_slice   ep_cl;
        cfs_mutex_t            ep_lock;
        cfs_page_t            *ep_vmpage;
};

struct echo_lock {
        struct cl_lock_slice   el_cl;
        cfs_list_t             el_chain;
        struct echo_object    *el_object;
        __u64                  el_cookie;
        cfs_atomic_t           el_refcount;
};

struct echo_io {
        struct cl_io_slice     ei_cl;
};

#if 0
struct echo_req {
        struct cl_req_slice er_cl;
};
#endif

static int echo_client_setup(struct obd_device *obddev,
                             struct lustre_cfg *lcfg);
static int echo_client_cleanup(struct obd_device *obddev);


/** \defgroup echo_helpers Helper functions
 * @{
 */
static inline struct echo_device *cl2echo_dev(const struct cl_device *dev)
{
        return container_of0(dev, struct echo_device, ed_cl);
}

static inline struct cl_device *echo_dev2cl(struct echo_device *d)
{
        return &d->ed_cl;
}

static inline struct echo_device *obd2echo_dev(const struct obd_device *obd)
{
        return cl2echo_dev(lu2cl_dev(obd->obd_lu_dev));
}

static inline struct cl_object *echo_obj2cl(struct echo_object *eco)
{
        return &eco->eo_cl;
}

static inline struct echo_object *cl2echo_obj(const struct cl_object *o)
{
        return container_of(o, struct echo_object, eo_cl);
}

static inline struct echo_page *cl2echo_page(const struct cl_page_slice *s)
{
        return container_of(s, struct echo_page, ep_cl);
}

static inline struct echo_lock *cl2echo_lock(const struct cl_lock_slice *s)
{
        return container_of(s, struct echo_lock, el_cl);
}

static inline struct cl_lock *echo_lock2cl(const struct echo_lock *ecl)
{
        return ecl->el_cl.cls_lock;
}

static struct lu_context_key echo_thread_key;
static inline struct echo_thread_info *echo_env_info(const struct lu_env *env)
{
        struct echo_thread_info *info;
        info = lu_context_key_get(&env->le_ctx, &echo_thread_key);
        LASSERT(info != NULL);
        return info;
}

static inline
struct echo_object_conf *cl2echo_conf(const struct cl_object_conf *c)
{
        return container_of(c, struct echo_object_conf, eoc_cl);
}

static inline void lsm2fid(struct lov_stripe_md *lsm, struct lu_fid *fid)
{
        fid_zero(fid);
        fid->f_seq = FID_SEQ_ECHO;
        /* truncated to 32 bits by assignment */
        fid->f_oid = lsm->lsm_object_id;
        fid->f_ver = lsm->lsm_object_id >> 32;
}
/** @} echo_helpers */

static struct echo_object *cl_echo_object_find(struct echo_device *d,
                                               struct lov_stripe_md **lsm);
static int cl_echo_object_put(struct echo_object *eco);
static int cl_echo_enqueue   (struct echo_object *eco, obd_off start,
                              obd_off end, int mode, __u64 *cookie);
static int cl_echo_cancel    (struct echo_device *d, __u64 cookie);
static int cl_echo_object_brw(struct echo_object *eco, int rw, obd_off offset,
                              cfs_page_t **pages, int npages, int async);

static struct echo_thread_info *echo_env_info(const struct lu_env *env);

struct echo_thread_info {
        struct echo_object_conf eti_conf;
        struct lustre_md        eti_md;

        struct cl_2queue        eti_queue;
        struct cl_io            eti_io;
        struct cl_lock_descr    eti_descr;
        struct lu_fid           eti_fid;
};

/* No session used right now */
struct echo_session_info {
        unsigned long dummy;
};

static cfs_mem_cache_t *echo_page_kmem;
static cfs_mem_cache_t *echo_lock_kmem;
static cfs_mem_cache_t *echo_object_kmem;
static cfs_mem_cache_t *echo_thread_kmem;
static cfs_mem_cache_t *echo_session_kmem;
//static cfs_mem_cache_t *echo_req_kmem;

static struct lu_kmem_descr echo_caches[] = {
        {
                .ckd_cache = &echo_page_kmem,
                .ckd_name  = "echo_page_kmem",
                .ckd_size  = sizeof (struct echo_page)
        },
        {
                .ckd_cache = &echo_lock_kmem,
                .ckd_name  = "echo_lock_kmem",
                .ckd_size  = sizeof (struct echo_lock)
        },
        {
                .ckd_cache = &echo_object_kmem,
                .ckd_name  = "echo_object_kmem",
                .ckd_size  = sizeof (struct echo_object)
        },
        {
                .ckd_cache = &echo_thread_kmem,
                .ckd_name  = "echo_thread_kmem",
                .ckd_size  = sizeof (struct echo_thread_info)
        },
        {
                .ckd_cache = &echo_session_kmem,
                .ckd_name  = "echo_session_kmem",
                .ckd_size  = sizeof (struct echo_session_info)
        },
#if 0
        {
                .ckd_cache = &echo_req_kmem,
                .ckd_name  = "echo_req_kmem",
                .ckd_size  = sizeof (struct echo_req)
        },
#endif
        {
                .ckd_cache = NULL
        }
};

/** \defgroup echo_page Page operations
 *
 * Echo page operations.
 *
 * @{
 */
cfs_page_t *echo_page_vmpage(const struct lu_env *env,
                             const struct cl_page_slice *slice)
{
        return cl2echo_page(slice)->ep_vmpage;
}

static int echo_page_own(const struct lu_env *env,
                         const struct cl_page_slice *slice,
                         struct cl_io *io, int nonblock)
{
        struct echo_page *ep = cl2echo_page(slice);

        if (!nonblock)
                cfs_mutex_lock(&ep->ep_lock);
        else if (!cfs_mutex_trylock(&ep->ep_lock))
                return -EAGAIN;
        return 0;
}

static void echo_page_disown(const struct lu_env *env,
                             const struct cl_page_slice *slice,
                             struct cl_io *io)
{
        struct echo_page *ep = cl2echo_page(slice);

        LASSERT(cfs_mutex_is_locked(&ep->ep_lock));
        cfs_mutex_unlock(&ep->ep_lock);
}

static void echo_page_discard(const struct lu_env *env,
                              const struct cl_page_slice *slice,
                              struct cl_io *unused)
{
        cl_page_delete(env, slice->cpl_page);
}

static int echo_page_is_vmlocked(const struct lu_env *env,
                                 const struct cl_page_slice *slice)
{
        return cfs_mutex_is_locked(&cl2echo_page(slice)->ep_lock);
}

static void echo_page_completion(const struct lu_env *env,
                                 const struct cl_page_slice *slice,
                                 int ioret)
{
        LASSERT(slice->cpl_page->cp_sync_io != NULL);
}

static void echo_page_fini(const struct lu_env *env,
                           struct cl_page_slice *slice)
{
        struct echo_page *ep    = cl2echo_page(slice);
        struct echo_object *eco = cl2echo_obj(slice->cpl_obj);
        cfs_page_t *vmpage      = ep->ep_vmpage;
        ENTRY;

        cfs_atomic_dec(&eco->eo_npages);
        page_cache_release(vmpage);
        OBD_SLAB_FREE_PTR(ep, echo_page_kmem);
        EXIT;
}

static int echo_page_prep(const struct lu_env *env,
                          const struct cl_page_slice *slice,
                          struct cl_io *unused)
{
        return 0;
}

static int echo_page_print(const struct lu_env *env,
                           const struct cl_page_slice *slice,
                           void *cookie, lu_printer_t printer)
{
        struct echo_page *ep = cl2echo_page(slice);

        (*printer)(env, cookie, LUSTRE_ECHO_CLIENT_NAME"-page@%p %d vm@%p\n",
                   ep, cfs_mutex_is_locked(&ep->ep_lock), ep->ep_vmpage);
        return 0;
}

static const struct cl_page_operations echo_page_ops = {
        .cpo_own           = echo_page_own,
        .cpo_disown        = echo_page_disown,
        .cpo_discard       = echo_page_discard,
        .cpo_vmpage        = echo_page_vmpage,
        .cpo_fini          = echo_page_fini,
        .cpo_print         = echo_page_print,
        .cpo_is_vmlocked   = echo_page_is_vmlocked,
        .io = {
                [CRT_READ] = {
                        .cpo_prep        = echo_page_prep,
                        .cpo_completion  = echo_page_completion,
                },
                [CRT_WRITE] = {
                        .cpo_prep        = echo_page_prep,
                        .cpo_completion  = echo_page_completion,
                }
        }
};
/** @} echo_page */

/** \defgroup echo_lock Locking
 *
 * echo lock operations
 *
 * @{
 */
static void echo_lock_fini(const struct lu_env *env,
                           struct cl_lock_slice *slice)
{
        struct echo_lock *ecl = cl2echo_lock(slice);

        LASSERT(cfs_list_empty(&ecl->el_chain));
        OBD_SLAB_FREE_PTR(ecl, echo_lock_kmem);
}

static void echo_lock_delete(const struct lu_env *env,
                             const struct cl_lock_slice *slice)
{
        struct echo_lock *ecl      = cl2echo_lock(slice);

        LASSERT(cfs_list_empty(&ecl->el_chain));
}

static int echo_lock_fits_into(const struct lu_env *env,
                               const struct cl_lock_slice *slice,
                               const struct cl_lock_descr *need,
                               const struct cl_io *unused)
{
        return 1;
}

static struct cl_lock_operations echo_lock_ops = {
        .clo_fini      = echo_lock_fini,
        .clo_delete    = echo_lock_delete,
        .clo_fits_into = echo_lock_fits_into
};

/** @} echo_lock */

/** \defgroup echo_cl_ops cl_object operations
 *
 * operations for cl_object
 *
 * @{
 */
static struct cl_page *echo_page_init(const struct lu_env *env,
                                      struct cl_object *obj,
                                      struct cl_page *page, cfs_page_t *vmpage)
{
        struct echo_page *ep;
        ENTRY;

        OBD_SLAB_ALLOC_PTR_GFP(ep, echo_page_kmem, CFS_ALLOC_IO);
        if (ep != NULL) {
                struct echo_object *eco = cl2echo_obj(obj);
                ep->ep_vmpage = vmpage;
                page_cache_get(vmpage);
                cfs_mutex_init(&ep->ep_lock);
                cl_page_slice_add(page, &ep->ep_cl, obj, &echo_page_ops);
                cfs_atomic_inc(&eco->eo_npages);
        }
        RETURN(ERR_PTR(ep ? 0 : -ENOMEM));
}

static int echo_io_init(const struct lu_env *env, struct cl_object *obj,
                        struct cl_io *io)
{
        return 0;
}

static int echo_lock_init(const struct lu_env *env,
                          struct cl_object *obj, struct cl_lock *lock,
                          const struct cl_io *unused)
{
        struct echo_lock *el;
        ENTRY;

        OBD_SLAB_ALLOC_PTR_GFP(el, echo_lock_kmem, CFS_ALLOC_IO);
        if (el != NULL) {
                cl_lock_slice_add(lock, &el->el_cl, obj, &echo_lock_ops);
                el->el_object = cl2echo_obj(obj);
                CFS_INIT_LIST_HEAD(&el->el_chain);
                cfs_atomic_set(&el->el_refcount, 0);
        }
        RETURN(el == NULL ? -ENOMEM : 0);
}

static int echo_conf_set(const struct lu_env *env, struct cl_object *obj,
                         const struct cl_object_conf *conf)
{
        return 0;
}

static const struct cl_object_operations echo_cl_obj_ops = {
        .coo_page_init = echo_page_init,
        .coo_lock_init = echo_lock_init,
        .coo_io_init   = echo_io_init,
        .coo_conf_set  = echo_conf_set
};
/** @} echo_cl_ops */

/** \defgroup echo_lu_ops lu_object operations
 *
 * operations for echo lu object.
 *
 * @{
 */
static int echo_object_init(const struct lu_env *env, struct lu_object *obj,
                            const struct lu_object_conf *conf)
{
        const struct cl_object_conf *cconf = lu2cl_conf(conf);
        struct echo_object_conf *econf = cl2echo_conf(cconf);
        struct echo_device *ed         = cl2echo_dev(lu2cl_dev(obj->lo_dev));
        struct echo_client_obd *ec     = ed->ed_ec;
        struct echo_object *eco        = cl2echo_obj(lu2cl(obj));
        ENTRY;

        if (ed->ed_next) {
                struct lu_object  *below;
                struct lu_device  *under;

                under = ed->ed_next;
                below = under->ld_ops->ldo_object_alloc(env, obj->lo_header,
                                                        under);
                if (below == NULL)
                        RETURN(-ENOMEM);
                lu_object_add(obj, below);
        }

        LASSERT(econf->eoc_md);
        eco->eo_lsm = *econf->eoc_md;
        eco->eo_dev = ed;
        cfs_atomic_set(&eco->eo_npages, 0);

        /* clear the lsm pointer so that it won't get freed. */
        *econf->eoc_md = NULL;

        cfs_spin_lock(&ec->ec_lock);
        cfs_list_add_tail(&eco->eo_obj_chain, &ec->ec_objects);
        cfs_spin_unlock(&ec->ec_lock);

        RETURN(0);
}

static void echo_object_free(const struct lu_env *env, struct lu_object *obj)
{
        struct echo_object *eco    = cl2echo_obj(lu2cl(obj));
        struct echo_client_obd *ec = eco->eo_dev->ed_ec;
        struct lov_stripe_md *lsm  = eco->eo_lsm;
        ENTRY;

        LASSERT(cfs_atomic_read(&eco->eo_npages) == 0);

        cfs_spin_lock(&ec->ec_lock);
        cfs_list_del_init(&eco->eo_obj_chain);
        cfs_spin_unlock(&ec->ec_lock);

        lu_object_fini(obj);
        lu_object_header_fini(obj->lo_header);

        if (lsm)
                obd_free_memmd(ec->ec_exp, &lsm);
        OBD_SLAB_FREE_PTR(eco, echo_object_kmem);
        EXIT;
}

static int echo_object_print(const struct lu_env *env, void *cookie,
                            lu_printer_t p, const struct lu_object *o)
{
        struct echo_object *obj = cl2echo_obj(lu2cl(o));

        return (*p)(env, cookie, "echoclient-object@%p", obj);
}


static const struct lu_object_operations echo_lu_obj_ops = {
        .loo_object_init      = echo_object_init,
        .loo_object_delete    = NULL,
        .loo_object_release   = NULL,
        .loo_object_free      = echo_object_free,
        .loo_object_print     = echo_object_print,
        .loo_object_invariant = NULL
};
/** @} echo_lu_ops */

/** \defgroup echo_lu_dev_ops  lu_device operations
 *
 * Operations for echo lu device.
 *
 * @{
 */
static struct lu_object *echo_object_alloc(const struct lu_env *env,
                                           const struct lu_object_header *hdr,
                                           struct lu_device *dev)
{
        struct echo_object *eco;
        struct lu_object *obj = NULL;
        ENTRY;

        /* we're the top dev. */
        LASSERT(hdr == NULL);
        OBD_SLAB_ALLOC_PTR_GFP(eco, echo_object_kmem, CFS_ALLOC_IO);
        if (eco != NULL) {
                struct cl_object_header *hdr = &eco->eo_hdr;

                obj = &echo_obj2cl(eco)->co_lu;
                cl_object_header_init(hdr);
                lu_object_init(obj, &hdr->coh_lu, dev);
                lu_object_add_top(&hdr->coh_lu, obj);

                eco->eo_cl.co_ops = &echo_cl_obj_ops;
                obj->lo_ops       = &echo_lu_obj_ops;
        }
        RETURN(obj);
}

static struct lu_device_operations echo_device_lu_ops = {
        .ldo_object_alloc   = echo_object_alloc,
};
/** @} echo_lu_dev_ops */

static struct cl_device_operations echo_device_cl_ops = {
};

/** \defgroup echo_init Setup and teardown
 *
 * Init and fini functions for echo client.
 *
 * @{
 */
static int echo_site_init(const struct lu_env *env, struct echo_device *ed)
{
        struct cl_site *site = &ed->ed_site_myself;
        int rc;

        /* initialize site */
        rc = cl_site_init(site, &ed->ed_cl);
        if (rc) {
                CERROR("Cannot initilize site for echo client(%d)\n", rc);
                return rc;
        }

        rc = lu_site_init_finish(&site->cs_lu);
        if (rc)
                return rc;

        ed->ed_site = site;
        return 0;
}

static void echo_site_fini(const struct lu_env *env, struct echo_device *ed)
{
        if (ed->ed_site) {
                cl_site_fini(ed->ed_site);
                ed->ed_site = NULL;
        }
}

static void *echo_thread_key_init(const struct lu_context *ctx,
                          struct lu_context_key *key)
{
        struct echo_thread_info *info;

        OBD_SLAB_ALLOC_PTR_GFP(info, echo_thread_kmem, CFS_ALLOC_IO);
        if (info == NULL)
                info = ERR_PTR(-ENOMEM);
        return info;
}

static void echo_thread_key_fini(const struct lu_context *ctx,
                         struct lu_context_key *key, void *data)
{
        struct echo_thread_info *info = data;
        OBD_SLAB_FREE_PTR(info, echo_thread_kmem);
}

static void echo_thread_key_exit(const struct lu_context *ctx,
                         struct lu_context_key *key, void *data)
{
}

static struct lu_context_key echo_thread_key = {
        .lct_tags = LCT_CL_THREAD,
        .lct_init = echo_thread_key_init,
        .lct_fini = echo_thread_key_fini,
        .lct_exit = echo_thread_key_exit
};

static void *echo_session_key_init(const struct lu_context *ctx,
                                  struct lu_context_key *key)
{
        struct echo_session_info *session;

        OBD_SLAB_ALLOC_PTR_GFP(session, echo_session_kmem, CFS_ALLOC_IO);
        if (session == NULL)
                session = ERR_PTR(-ENOMEM);
        return session;
}

static void echo_session_key_fini(const struct lu_context *ctx,
                                 struct lu_context_key *key, void *data)
{
        struct echo_session_info *session = data;
        OBD_SLAB_FREE_PTR(session, echo_session_kmem);
}

static void echo_session_key_exit(const struct lu_context *ctx,
                                 struct lu_context_key *key, void *data)
{
}

static struct lu_context_key echo_session_key = {
        .lct_tags = LCT_SESSION,
        .lct_init = echo_session_key_init,
        .lct_fini = echo_session_key_fini,
        .lct_exit = echo_session_key_exit
};

LU_TYPE_INIT_FINI(echo, &echo_thread_key, &echo_session_key);

static struct lu_device *echo_device_alloc(const struct lu_env *env,
                                           struct lu_device_type *t,
                                           struct lustre_cfg *cfg)
{
        struct lu_device   *next;
        struct echo_device *ed;
        struct cl_device   *cd;
        struct obd_device  *obd = NULL; /* to keep compiler happy */
        struct obd_device  *tgt;
        const char *tgt_type_name;
        int rc;
        int cleanup = 0;
        ENTRY;

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

        cleanup = 1;
        cd = &ed->ed_cl;
        rc = cl_device_init(cd, t);
        if (rc)
                GOTO(out, rc);

        cd->cd_lu_dev.ld_ops = &echo_device_lu_ops;
        cd->cd_ops = &echo_device_cl_ops;

        cleanup = 2;
        rc = echo_site_init(env, ed);
        if (rc)
                GOTO(out, rc);

        cleanup = 3;
        obd = class_name2obd(lustre_cfg_string(cfg, 0));
        LASSERT(obd != NULL);
        rc = echo_client_setup(obd, cfg);
        if (rc)
                GOTO(out, rc);
        ed->ed_ec = &obd->u.echo_client;

        cleanup = 4;
        tgt = class_name2obd(lustre_cfg_string(cfg, 1));
        LASSERT(tgt != NULL);
        next = tgt->obd_lu_dev;
        if (next != NULL && !lu_device_is_cl(next))
                next = NULL;

        /*
         * if echo client is to be stacked upon ost device, the next is NULL
         * since ost is not a clio device so far
         */
        tgt_type_name = tgt->obd_type->typ_name;
        if (next != NULL) {
                LASSERT(next != NULL);
                if (next->ld_site != NULL)
                        GOTO(out, rc = -EBUSY);

                next->ld_site = &ed->ed_site->cs_lu;
                rc = next->ld_type->ldt_ops->ldto_device_init(env, next,
                                             next->ld_type->ldt_name, NULL);
                if (rc)
                        GOTO(out, rc);

                /* Trikcy case, I have to determine the obd type since clio
                 * uses the different parameters to initialize objects for
                 * lov & osc.
                 */
                if (strcmp(tgt_type_name, LUSTRE_LOV_NAME) == 0)
                        ed->ed_next_islov = 1;
                else
                        LASSERT(strcmp(tgt_type_name, LUSTRE_OSC_NAME) == 0);
        } else
                LASSERT(strcmp(tgt_type_name, LUSTRE_OST_NAME) == 0);

        ed->ed_next = next;
        RETURN(&cd->cd_lu_dev);

out:
        switch(cleanup) {
        case 4: {
                int rc2;
                rc2 = echo_client_cleanup(obd);
                if (rc2)
                        CERROR("Cleanup obd device %s error(%d)\n",
                               obd->obd_name, rc2);
        }

        case 3:
                echo_site_fini(env, ed);
        case 2:
                cl_device_fini(&ed->ed_cl);
        case 1:
                OBD_FREE_PTR(ed);
        case 0:
        default:
                break;
        }
        return(ERR_PTR(rc));
}

static int echo_device_init(const struct lu_env *env, struct lu_device *d,
                          const char *name, struct lu_device *next)
{
        LBUG();
        return 0;
}

static struct lu_device *echo_device_fini(const struct lu_env *env,
                                          struct lu_device *d)
{
        struct echo_device *ed = cl2echo_dev(lu2cl_dev(d));
        struct lu_device *next = ed->ed_next;

        while (next)
                next = next->ld_type->ldt_ops->ldto_device_fini(env, next);
        return NULL;
}

static void echo_lock_release(const struct lu_env *env,
                              struct echo_lock *ecl,
                              int still_used)
{
        struct cl_lock *clk = echo_lock2cl(ecl);

        cl_lock_get(clk);
        cl_unuse(env, clk);
        cl_lock_release(env, clk, "ec enqueue", ecl->el_object);
        if (!still_used) {
                cl_lock_mutex_get(env, clk);
                cl_lock_cancel(env, clk);
                cl_lock_delete(env, clk);
                cl_lock_mutex_put(env, clk);
        }
        cl_lock_put(env, clk);
}

static struct lu_device *echo_device_free(const struct lu_env *env,
                                          struct lu_device *d)
{
        struct echo_device     *ed   = cl2echo_dev(lu2cl_dev(d));
        struct echo_client_obd *ec   = ed->ed_ec;
        struct echo_object     *eco;
        struct lu_device       *next = ed->ed_next;

        CDEBUG(D_INFO, "echo device:%p is going to be freed, next = %p\n",
               ed, next);

        LASSERT(ed->ed_site);
        lu_site_purge(env, &ed->ed_site->cs_lu, -1);

        /* check if there are objects still alive.
         * It shouldn't have any object because lu_site_purge would cleanup
         * all of cached objects. Anyway, probably the echo device is being
         * parallelly accessed.
         */
        cfs_spin_lock(&ec->ec_lock);
        cfs_list_for_each_entry(eco, &ec->ec_objects, eo_obj_chain)
                eco->eo_deleted = 1;
        cfs_spin_unlock(&ec->ec_lock);

        /* purge again */
        lu_site_purge(env, &ed->ed_site->cs_lu, -1);

        CDEBUG(D_INFO,
               "Waiting for the reference of echo object to be dropped\n");

        /* Wait for the last reference to be dropped. */
        cfs_spin_lock(&ec->ec_lock);
        while (!cfs_list_empty(&ec->ec_objects)) {
                cfs_spin_unlock(&ec->ec_lock);
                CERROR("echo_client still has objects at cleanup time, "
                       "wait for 1 second\n");
                cfs_schedule_timeout_and_set_state(CFS_TASK_UNINT,
                                                   cfs_time_seconds(1));
                cfs_spin_lock(&ec->ec_lock);
        }
        cfs_spin_unlock(&ec->ec_lock);

        LASSERT(cfs_list_empty(&ec->ec_locks));

        CDEBUG(D_INFO, "No object exists, exiting...\n");

        echo_client_cleanup(d->ld_obd);

        while (next)
                next = next->ld_type->ldt_ops->ldto_device_free(env, next);

        LASSERT(ed->ed_site == lu2cl_site(d->ld_site));
        echo_site_fini(env, ed);
        cl_device_fini(&ed->ed_cl);
        OBD_FREE_PTR(ed);

        return NULL;
}

static const struct lu_device_type_operations echo_device_type_ops = {
        .ldto_init = echo_type_init,
        .ldto_fini = echo_type_fini,

        .ldto_start = echo_type_start,
        .ldto_stop  = echo_type_stop,

        .ldto_device_alloc = echo_device_alloc,
        .ldto_device_free  = echo_device_free,
        .ldto_device_init  = echo_device_init,
        .ldto_device_fini  = echo_device_fini
};

static struct lu_device_type echo_device_type = {
        .ldt_tags     = LU_DEVICE_CL,
        .ldt_name     = LUSTRE_ECHO_CLIENT_NAME,
        .ldt_ops      = &echo_device_type_ops,
        .ldt_ctx_tags = LCT_CL_THREAD
};
/** @} echo_init */

/** \defgroup echo_exports Exported operations
 *
 * exporting functions to echo client
 *
 * @{
 */

/* Interfaces to echo client obd device */
static struct echo_object *cl_echo_object_find(struct echo_device *d,
                                               struct lov_stripe_md **lsmp)
{
        struct lu_env *env;
        struct echo_thread_info *info;
        struct echo_object_conf *conf;
        struct lov_stripe_md    *lsm;
        struct echo_object *eco;
        struct cl_object   *obj;
        struct lu_fid *fid;
        int refcheck;
        ENTRY;

        LASSERT(lsmp);
        lsm = *lsmp;
        LASSERT(lsm);
        LASSERT(lsm->lsm_object_id);

        /* Never return an object if the obd is to be freed. */
        if (echo_dev2cl(d)->cd_lu_dev.ld_obd->obd_stopping)
                RETURN(ERR_PTR(-ENODEV));

        env = cl_env_get(&refcheck);
        if (IS_ERR(env))
                RETURN((void *)env);

        info = echo_env_info(env);
        conf = &info->eti_conf;
        if (d->ed_next) {
                if (!d->ed_next_islov) {
                        struct lov_oinfo *oinfo = lsm->lsm_oinfo[0];
                        LASSERT(oinfo != NULL);
                        oinfo->loi_id = lsm->lsm_object_id;
                        oinfo->loi_seq = lsm->lsm_object_seq;
                        conf->eoc_cl.u.coc_oinfo = oinfo;
                } else {
                        struct lustre_md *md;
                        md = &info->eti_md;
                        memset(md, 0, sizeof *md);
                        md->lsm = lsm;
                        conf->eoc_cl.u.coc_md = md;
                }
        }
        conf->eoc_md = lsmp;

        fid  = &info->eti_fid;
        lsm2fid(lsm, fid);

        obj = cl_object_find(env, echo_dev2cl(d), fid, &conf->eoc_cl);
        if (IS_ERR(obj))
                GOTO(out, eco = (void*)obj);

        eco = cl2echo_obj(obj);
        if (eco->eo_deleted) {
                cl_object_put(env, obj);
                eco = ERR_PTR(-EAGAIN);
        }

out:
        cl_env_put(env, &refcheck);
        RETURN(eco);
}

static int cl_echo_object_put(struct echo_object *eco)
{
        struct lu_env *env;
        struct cl_object *obj = echo_obj2cl(eco);
        int refcheck;
        ENTRY;

        env = cl_env_get(&refcheck);
        if (IS_ERR(env))
                RETURN(PTR_ERR(env));

        /* an external function to kill an object? */
        if (eco->eo_deleted) {
                struct lu_object_header *loh = obj->co_lu.lo_header;
                LASSERT(&eco->eo_hdr == luh2coh(loh));
                cfs_set_bit(LU_OBJECT_HEARD_BANSHEE, &loh->loh_flags);
        }

        cl_object_put(env, obj);
        cl_env_put(env, &refcheck);
        RETURN(0);
}

static int cl_echo_enqueue0(struct lu_env *env, struct echo_object *eco,
                            obd_off start, obd_off end, int mode,
                            __u64 *cookie , __u32 enqflags)
{
        struct cl_io *io;
        struct cl_lock *lck;
        struct cl_object *obj;
        struct cl_lock_descr *descr;
        struct echo_thread_info *info;
        int rc = -ENOMEM;
        ENTRY;

        info = echo_env_info(env);
        io = &info->eti_io;
        descr = &info->eti_descr;
        obj = echo_obj2cl(eco);

        descr->cld_obj   = obj;
        descr->cld_start = cl_index(obj, start);
        descr->cld_end   = cl_index(obj, end);
        descr->cld_mode  = mode == LCK_PW ? CLM_WRITE : CLM_READ;
        descr->cld_enq_flags = enqflags;
        io->ci_obj = obj;

        lck = cl_lock_request(env, io, descr, "ec enqueue", eco);
        if (lck) {
                struct echo_client_obd *ec = eco->eo_dev->ed_ec;
                struct echo_lock *el;

                rc = cl_wait(env, lck);
                if (rc == 0) {
                        el = cl2echo_lock(cl_lock_at(lck, &echo_device_type));
                        cfs_spin_lock(&ec->ec_lock);
                        if (cfs_list_empty(&el->el_chain)) {
                                cfs_list_add(&el->el_chain, &ec->ec_locks);
                                el->el_cookie = ++ec->ec_unique;
                        }
                        cfs_atomic_inc(&el->el_refcount);
                        *cookie = el->el_cookie;
                        cfs_spin_unlock(&ec->ec_lock);
                } else
                        cl_lock_release(env, lck, "ec enqueue", cfs_current());
        }
        RETURN(rc);
}

static int cl_echo_enqueue(struct echo_object *eco, obd_off start, obd_off end,
                           int mode, __u64 *cookie)
{
        struct echo_thread_info *info;
        struct lu_env *env;
        struct cl_io *io;
        int refcheck;
        int result;
        ENTRY;

        env = cl_env_get(&refcheck);
        if (IS_ERR(env))
                RETURN(PTR_ERR(env));

        info = echo_env_info(env);
        io = &info->eti_io;

        result = cl_io_init(env, io, CIT_MISC, echo_obj2cl(eco));
        if (result < 0)
                GOTO(out, result);
        LASSERT(result == 0);

        result = cl_echo_enqueue0(env, eco, start, end, mode, cookie, 0);
        cl_io_fini(env, io);

        EXIT;
out:
        cl_env_put(env, &refcheck);
        return result;
}

static int cl_echo_cancel0(struct lu_env *env, struct echo_device *ed,
                           __u64 cookie)
{
        struct echo_client_obd *ec = ed->ed_ec;
        struct echo_lock       *ecl = NULL;
        cfs_list_t             *el;
        int found = 0, still_used = 0;
        ENTRY;

        LASSERT(ec != NULL);
        cfs_spin_lock (&ec->ec_lock);
        cfs_list_for_each (el, &ec->ec_locks) {
                ecl = cfs_list_entry (el, struct echo_lock, el_chain);
                CDEBUG(D_INFO, "ecl: %p, cookie: "LPX64"\n", ecl, ecl->el_cookie);
                found = (ecl->el_cookie == cookie);
                if (found) {
                        if (cfs_atomic_dec_and_test(&ecl->el_refcount))
                                cfs_list_del_init(&ecl->el_chain);
                        else
                                still_used = 1;
                        break;
                }
        }
        cfs_spin_unlock (&ec->ec_lock);

        if (!found)
                RETURN(-ENOENT);

        echo_lock_release(env, ecl, still_used);
        RETURN(0);
}

static int cl_echo_cancel(struct echo_device *ed, __u64 cookie)
{
        struct lu_env *env;
        int refcheck;
        int rc;
        ENTRY;

        env = cl_env_get(&refcheck);
        if (IS_ERR(env))
                RETURN(PTR_ERR(env));

        rc = cl_echo_cancel0(env, ed, cookie);

        cl_env_put(env, &refcheck);
        RETURN(rc);
}

static int cl_echo_async_brw(const struct lu_env *env, struct cl_io *io,
                             enum cl_req_type unused, struct cl_2queue *queue)
{
        struct cl_page *clp;
        struct cl_page *temp;
        int result = 0;
        ENTRY;

        cl_page_list_for_each_safe(clp, temp, &queue->c2_qin) {
                int rc;
                rc = cl_page_cache_add(env, io, clp, CRT_WRITE);
                if (rc == 0)
                        continue;
                result = result ?: rc;
        }
        RETURN(result);
}

static int cl_echo_object_brw(struct echo_object *eco, int rw, obd_off offset,
                              cfs_page_t **pages, int npages, int async)
{
        struct lu_env           *env;
        struct echo_thread_info *info;
        struct cl_object        *obj = echo_obj2cl(eco);
        struct echo_device      *ed  = eco->eo_dev;
        struct cl_2queue        *queue;
        struct cl_io            *io;
        struct cl_page          *clp;
        struct lustre_handle    lh = { 0 };
        int page_size = cl_page_size(obj);
        int refcheck;
        int rc;
        int i;
        ENTRY;

        LASSERT((offset & ~CFS_PAGE_MASK) == 0);
        LASSERT(ed->ed_next != NULL);
        env = cl_env_get(&refcheck);
        if (IS_ERR(env))
                RETURN(PTR_ERR(env));

        info    = echo_env_info(env);
        io      = &info->eti_io;
        queue   = &info->eti_queue;

        cl_2queue_init(queue);
        rc = cl_io_init(env, io, CIT_MISC, obj);
        if (rc < 0)
                GOTO(out, rc);
        LASSERT(rc == 0);


        rc = cl_echo_enqueue0(env, eco, offset,
                              offset + npages * CFS_PAGE_SIZE - 1,
                              rw == READ ? LCK_PR : LCK_PW, &lh.cookie,
                              CEF_NEVER);
        if (rc < 0)
                GOTO(error_lock, rc);

        for (i = 0; i < npages; i++) {
                LASSERT(pages[i]);
                clp = cl_page_find(env, obj, cl_index(obj, offset),
                                   pages[i], CPT_TRANSIENT);
                if (IS_ERR(clp)) {
                        rc = PTR_ERR(clp);
                        break;
                }
                LASSERT(clp->cp_type == CPT_TRANSIENT);

                rc = cl_page_own(env, io, clp);
                if (rc) {
                        LASSERT(clp->cp_state == CPS_FREEING);
                        cl_page_put(env, clp);
                        break;
                }

                cl_2queue_add(queue, clp);

                /* drop the reference count for cl_page_find, so that the page
                 * will be freed in cl_2queue_fini. */
                cl_page_put(env, clp);
                cl_page_clip(env, clp, 0, page_size);

                offset += page_size;
        }

        if (rc == 0) {
                enum cl_req_type typ = rw == READ ? CRT_READ : CRT_WRITE;

                async = async && (typ == CRT_WRITE);
                if (async)
                        rc = cl_echo_async_brw(env, io, typ, queue);
                else
                        rc = cl_io_submit_sync(env, io, typ, queue,
                                               CRP_NORMAL, 0);
                CDEBUG(D_INFO, "echo_client %s write returns %d\n",
                       async ? "async" : "sync", rc);
        }

        cl_echo_cancel0(env, ed, lh.cookie);
        EXIT;
error_lock:
        cl_2queue_discard(env, io, queue);
        cl_2queue_disown(env, io, queue);
        cl_2queue_fini(env, queue);
        cl_io_fini(env, io);
out:
        cl_env_put(env, &refcheck);
        return rc;
}
/** @} echo_exports */


static obd_id last_object_id;

static int
echo_copyout_lsm (struct lov_stripe_md *lsm, void *_ulsm, int ulsm_nob)
{
        struct lov_stripe_md *ulsm = _ulsm;
        int nob, i;

        nob = offsetof (struct lov_stripe_md, lsm_oinfo[lsm->lsm_stripe_count]);
        if (nob > ulsm_nob)
                return (-EINVAL);

        if (cfs_copy_to_user (ulsm, lsm, sizeof(ulsm)))
                return (-EFAULT);

        for (i = 0; i < lsm->lsm_stripe_count; i++) {
                if (cfs_copy_to_user (ulsm->lsm_oinfo[i], lsm->lsm_oinfo[i],
                                      sizeof(lsm->lsm_oinfo[0])))
                        return (-EFAULT);
        }
        return 0;
}

static int
echo_copyin_lsm (struct echo_device *ed, struct lov_stripe_md *lsm,
                 void *ulsm, int ulsm_nob)
{
        struct echo_client_obd *ec = ed->ed_ec;
        int                     i;

        if (ulsm_nob < sizeof (*lsm))
                return (-EINVAL);

        if (cfs_copy_from_user (lsm, ulsm, sizeof (*lsm)))
                return (-EFAULT);

        if (lsm->lsm_stripe_count > ec->ec_nstripes ||
            lsm->lsm_magic != LOV_MAGIC ||
            (lsm->lsm_stripe_size & (~CFS_PAGE_MASK)) != 0 ||
            ((__u64)lsm->lsm_stripe_size * lsm->lsm_stripe_count > ~0UL))
                return (-EINVAL);


        for (i = 0; i < lsm->lsm_stripe_count; i++) {
                if (cfs_copy_from_user(lsm->lsm_oinfo[i],
                                       ((struct lov_stripe_md *)ulsm)-> \
                                       lsm_oinfo[i],
                                       sizeof(lsm->lsm_oinfo[0])))
                        return (-EFAULT);
        }
        return (0);
}

static int echo_create_object(struct echo_device *ed, int on_target,
                              struct obdo *oa, void *ulsm, int ulsm_nob,
                              struct obd_trans_info *oti)
{
        struct echo_object     *eco;
        struct echo_client_obd *ec = ed->ed_ec;
        struct lov_stripe_md   *lsm = NULL;
        int                     rc;
        int                     created = 0;
        ENTRY;

        if ((oa->o_valid & OBD_MD_FLID) == 0 && /* no obj id */
            (on_target ||                       /* set_stripe */
             ec->ec_nstripes != 0)) {           /* LOV */
                CERROR ("No valid oid\n");
                RETURN(-EINVAL);
        }

        rc = obd_alloc_memmd(ec->ec_exp, &lsm);
        if (rc < 0) {
                CERROR("Cannot allocate md, rc = %d\n", rc);
                GOTO(failed, rc);
        }

        if (ulsm != NULL) {
                int i, idx;

                rc = echo_copyin_lsm (ed, lsm, ulsm, ulsm_nob);
                if (rc != 0)
                        GOTO(failed, rc);

                if (lsm->lsm_stripe_count == 0)
                        lsm->lsm_stripe_count = ec->ec_nstripes;

                if (lsm->lsm_stripe_size == 0)
                        lsm->lsm_stripe_size = CFS_PAGE_SIZE;

                idx = cfs_rand();

                /* setup stripes: indices + default ids if required */
                for (i = 0; i < lsm->lsm_stripe_count; i++) {
                        if (lsm->lsm_oinfo[i]->loi_id == 0)
                                lsm->lsm_oinfo[i]->loi_id = lsm->lsm_object_id;

                        lsm->lsm_oinfo[i]->loi_ost_idx =
                                (idx + i) % ec->ec_nstripes;
                }
        }

        /* setup object ID here for !on_target and LOV hint */
        if (oa->o_valid & OBD_MD_FLID)
                lsm->lsm_object_id = oa->o_id;

        if (lsm->lsm_object_id == 0)
                lsm->lsm_object_id = ++last_object_id;

        rc = 0;
        if (on_target) {
                /* Only echo objects are allowed to be created */
                LASSERT((oa->o_valid & OBD_MD_FLGROUP) &&
                        (oa->o_seq == FID_SEQ_ECHO));
                rc = obd_create(ec->ec_exp, oa, &lsm, oti);
                if (rc != 0) {
                        CERROR("Cannot create objects, rc = %d\n", rc);
                        GOTO(failed, rc);
                }
                created = 1;
        }

        /* See what object ID we were given */
        oa->o_id = lsm->lsm_object_id;
        oa->o_valid |= OBD_MD_FLID;

        eco = cl_echo_object_find(ed, &lsm);
        if (IS_ERR(eco))
                GOTO(failed, rc = PTR_ERR(eco));
        cl_echo_object_put(eco);

        CDEBUG(D_INFO, "oa->o_id = %lx\n", (long)oa->o_id);
        EXIT;

 failed:
        if (created && rc)
                obd_destroy(ec->ec_exp, oa, lsm, oti, NULL, NULL);
        if (lsm)
                obd_free_memmd(ec->ec_exp, &lsm);
        if (rc)
                CERROR("create object failed with rc = %d\n", rc);
        return (rc);
}

static int echo_get_object(struct echo_object **ecop, struct echo_device *ed,
                           struct obdo *oa)
{
        struct echo_client_obd *ec  = ed->ed_ec;
        struct lov_stripe_md   *lsm = NULL;
        struct echo_object     *eco;
        int                     rc;
        ENTRY;

        if ((oa->o_valid & OBD_MD_FLID) == 0 ||
            oa->o_id == 0)  /* disallow use of object id 0 */
        {
                CERROR ("No valid oid\n");
                RETURN(-EINVAL);
        }

        rc = obd_alloc_memmd(ec->ec_exp, &lsm);
        if (rc < 0)
                RETURN(rc);

        lsm->lsm_object_id = oa->o_id;
        if (oa->o_valid & OBD_MD_FLGROUP)
                lsm->lsm_object_seq = oa->o_seq;
        else
                lsm->lsm_object_seq = FID_SEQ_ECHO;

        rc = 0;
        eco = cl_echo_object_find(ed, &lsm);
        if (!IS_ERR(eco))
                *ecop = eco;
        else
                rc = PTR_ERR(eco);
        if (lsm)
                obd_free_memmd(ec->ec_exp, &lsm);
        RETURN(rc);
}

static void echo_put_object(struct echo_object *eco)
{
        if (cl_echo_object_put(eco))
                CERROR("echo client: drop an object failed");
}

static void
echo_get_stripe_off_id (struct lov_stripe_md *lsm, obd_off *offp, obd_id *idp)
{
        unsigned long stripe_count;
        unsigned long stripe_size;
        unsigned long width;
        unsigned long woffset;
        int           stripe_index;
        obd_off       offset;

        if (lsm->lsm_stripe_count <= 1)
                return;

        offset       = *offp;
        stripe_size  = lsm->lsm_stripe_size;
        stripe_count = lsm->lsm_stripe_count;

        /* width = # bytes in all stripes */
        width = stripe_size * stripe_count;

        /* woffset = offset within a width; offset = whole number of widths */
        woffset = do_div (offset, width);

        stripe_index = woffset / stripe_size;

        *idp = lsm->lsm_oinfo[stripe_index]->loi_id;
        *offp = offset * stripe_size + woffset % stripe_size;
}

static void
echo_client_page_debug_setup(struct lov_stripe_md *lsm,
                             cfs_page_t *page, int rw, obd_id id,
                             obd_off offset, obd_off count)
{
        char    *addr;
        obd_off  stripe_off;
        obd_id   stripe_id;
        int      delta;

        /* no partial pages on the client */
        LASSERT(count == CFS_PAGE_SIZE);

        addr = cfs_kmap(page);

        for (delta = 0; delta < CFS_PAGE_SIZE; delta += OBD_ECHO_BLOCK_SIZE) {
                if (rw == OBD_BRW_WRITE) {
                        stripe_off = offset + delta;
                        stripe_id = id;
                        echo_get_stripe_off_id(lsm, &stripe_off, &stripe_id);
                } else {
                        stripe_off = 0xdeadbeef00c0ffeeULL;
                        stripe_id = 0xdeadbeef00c0ffeeULL;
                }
                block_debug_setup(addr + delta, OBD_ECHO_BLOCK_SIZE,
                                  stripe_off, stripe_id);
        }

        cfs_kunmap(page);
}

static int echo_client_page_debug_check(struct lov_stripe_md *lsm,
                                        cfs_page_t *page, obd_id id,
                                        obd_off offset, obd_off count)
{
        obd_off stripe_off;
        obd_id  stripe_id;
        char   *addr;
        int     delta;
        int     rc;
        int     rc2;

        /* no partial pages on the client */
        LASSERT(count == CFS_PAGE_SIZE);

        addr = cfs_kmap(page);

        for (rc = delta = 0; delta < CFS_PAGE_SIZE; delta += OBD_ECHO_BLOCK_SIZE) {
                stripe_off = offset + delta;
                stripe_id = id;
                echo_get_stripe_off_id (lsm, &stripe_off, &stripe_id);

                rc2 = block_debug_check("test_brw",
                                        addr + delta, OBD_ECHO_BLOCK_SIZE,
                                        stripe_off, stripe_id);
                if (rc2 != 0) {
                        CERROR ("Error in echo object "LPX64"\n", id);
                        rc = rc2;
                }
        }

        cfs_kunmap(page);
        return rc;
}

static int echo_client_kbrw(struct echo_device *ed, int rw, struct obdo *oa,
                            struct echo_object *eco, obd_off offset,
                            obd_size count, int async,
                            struct obd_trans_info *oti)
{
        struct echo_client_obd *ec  = ed->ed_ec;
        struct lov_stripe_md   *lsm = eco->eo_lsm;
        obd_count               npages;
        struct brw_page        *pga;
        struct brw_page        *pgp;
        cfs_page_t            **pages;
        obd_off                 off;
        int                     i;
        int                     rc;
        int                     verify;
        int                     gfp_mask;
        int                     brw_flags = 0;
        ENTRY;

        verify = ((oa->o_id) != ECHO_PERSISTENT_OBJID &&
                  (oa->o_valid & OBD_MD_FLFLAGS) != 0 &&
                  (oa->o_flags & OBD_FL_DEBUG_CHECK) != 0);

        gfp_mask = ((oa->o_id & 2) == 0) ? CFS_ALLOC_STD : CFS_ALLOC_HIGHUSER;

        LASSERT(rw == OBD_BRW_WRITE || rw == OBD_BRW_READ);
        LASSERT(lsm != NULL);
        LASSERT(lsm->lsm_object_id == oa->o_id);

        if (count <= 0 ||
            (count & (~CFS_PAGE_MASK)) != 0)
                RETURN(-EINVAL);

        /* XXX think again with misaligned I/O */
        npages = count >> CFS_PAGE_SHIFT;

        if (rw == OBD_BRW_WRITE)
                brw_flags = OBD_BRW_ASYNC;

        OBD_ALLOC(pga, npages * sizeof(*pga));
        if (pga == NULL)
                RETURN(-ENOMEM);

        OBD_ALLOC(pages, npages * sizeof(*pages));
        if (pages == NULL) {
                OBD_FREE(pga, npages * sizeof(*pga));
                RETURN(-ENOMEM);
        }

        for (i = 0, pgp = pga, off = offset;
             i < npages;
             i++, pgp++, off += CFS_PAGE_SIZE) {

                LASSERT (pgp->pg == NULL);      /* for cleanup */

                rc = -ENOMEM;
                OBD_PAGE_ALLOC(pgp->pg, gfp_mask);
                if (pgp->pg == NULL)
                        goto out;

                pages[i] = pgp->pg;
                pgp->count = CFS_PAGE_SIZE;
                pgp->off = off;
                pgp->flag = brw_flags;

                if (verify)
                        echo_client_page_debug_setup(lsm, pgp->pg, rw,
                                                     oa->o_id, off, pgp->count);
        }

        if (ed->ed_next == NULL) {
                struct obd_info oinfo = { { { 0 } } };
                oinfo.oi_oa = oa;
                oinfo.oi_md = lsm;
                rc = obd_brw(rw, ec->ec_exp, &oinfo, npages, pga, oti);
        } else
                rc = cl_echo_object_brw(eco, rw, offset, pages, npages, async);

 out:
        if (rc != 0 || rw != OBD_BRW_READ)
                verify = 0;

        for (i = 0, pgp = pga; i < npages; i++, pgp++) {
                if (pgp->pg == NULL)
                        continue;

                if (verify) {
                        int vrc;
                        vrc = echo_client_page_debug_check(lsm, pgp->pg, oa->o_id,
                                                           pgp->off, pgp->count);
                        if (vrc != 0 && rc == 0)
                                rc = vrc;
                }
                OBD_PAGE_FREE(pgp->pg);
        }
        OBD_FREE(pga, npages * sizeof(*pga));
        OBD_FREE(pages, npages * sizeof(*pages));
        RETURN(rc);
}

static int echo_client_prep_commit(struct obd_export *exp, int rw,
                                   struct obdo *oa, struct echo_object *eco,
                                   obd_off offset, obd_size count,
                                   obd_size batch, struct obd_trans_info *oti)
{
        struct lov_stripe_md *lsm = eco->eo_lsm;
        struct obd_ioobj ioo;
        struct niobuf_local *lnb;
        struct niobuf_remote *rnb;
        obd_off off;
        obd_size npages, tot_pages;
        int i, ret = 0;
        ENTRY;

        if (count <= 0 || (count & (~CFS_PAGE_MASK)) != 0 ||
            (lsm != NULL && lsm->lsm_object_id != oa->o_id))
                RETURN(-EINVAL);

        npages = batch >> CFS_PAGE_SHIFT;
        tot_pages = count >> CFS_PAGE_SHIFT;

        OBD_ALLOC(lnb, npages * sizeof(struct niobuf_local));
        OBD_ALLOC(rnb, npages * sizeof(struct niobuf_remote));

        if (lnb == NULL || rnb == NULL)
                GOTO(out, ret = -ENOMEM);

        obdo_to_ioobj(oa, &ioo);

        off = offset;

        for(; tot_pages; tot_pages -= npages) {
                int lpages;

                if (tot_pages < npages)
                        npages = tot_pages;

                for (i = 0; i < npages; i++, off += CFS_PAGE_SIZE) {
                        rnb[i].offset = off;
                        rnb[i].len = CFS_PAGE_SIZE;
                }

                ioo.ioo_bufcnt = npages;
                oti->oti_transno = 0;

                lpages = npages;
                ret = obd_preprw(rw, exp, oa, 1, &ioo, rnb, &lpages, lnb, oti,
                                 NULL);
                if (ret != 0)
                        GOTO(out, ret);
                LASSERT(lpages == npages);

                for (i = 0; i < lpages; i++) {
                        cfs_page_t *page = lnb[i].page;

                        /* read past eof? */
                        if (page == NULL && lnb[i].rc == 0)
                                continue;

                        if (oa->o_id == ECHO_PERSISTENT_OBJID ||
                            (oa->o_valid & OBD_MD_FLFLAGS) == 0 ||
                            (oa->o_flags & OBD_FL_DEBUG_CHECK) == 0)
                                continue;

                        if (rw == OBD_BRW_WRITE)
                                echo_client_page_debug_setup(lsm, page, rw,
                                                             oa->o_id,
                                                             rnb[i].offset,
                                                             rnb[i].len);
                        else
                                echo_client_page_debug_check(lsm, page,
                                                             oa->o_id,
                                                             rnb[i].offset,
                                                             rnb[i].len);
                }

                ret = obd_commitrw(rw, exp, oa, 1,&ioo,rnb,npages,lnb,oti,ret);
                if (ret != 0)
                        GOTO(out, ret);

                /* Reset oti otherwise it would confuse ldiskfs. */
                memset(oti, 0, sizeof(*oti));
        }

out:
        if (lnb)
                OBD_FREE(lnb, npages * sizeof(struct niobuf_local));
        if (rnb)
                OBD_FREE(rnb, npages * sizeof(struct niobuf_remote));
        RETURN(ret);
}

static int echo_client_brw_ioctl(int rw, struct obd_export *exp,
                                 struct obd_ioctl_data *data)
{
        struct obd_device *obd = class_exp2obd(exp);
        struct echo_device *ed = obd2echo_dev(obd);
        struct echo_client_obd *ec = ed->ed_ec;
        struct obd_trans_info dummy_oti = { 0 };
        struct obdo *oa = &data->ioc_obdo1;
        struct echo_object *eco;
        int rc;
        int async = 1;
        ENTRY;

        LASSERT(oa->o_valid & OBD_MD_FLGROUP);

        rc = echo_get_object(&eco, ed, oa);
        if (rc)
                RETURN(rc);

        oa->o_valid &= ~OBD_MD_FLHANDLE;

        switch((long)data->ioc_pbuf1) {
        case 1:
                async = 0;
                /* fall through */
        case 2:
                rc = echo_client_kbrw(ed, rw, oa,
                                      eco, data->ioc_offset,
                                      data->ioc_count, async, &dummy_oti);
                break;
        case 3:
                rc = echo_client_prep_commit(ec->ec_exp, rw, oa,
                                            eco, data->ioc_offset,
                                            data->ioc_count, data->ioc_plen1,
                                            &dummy_oti);
                break;
        default:
                rc = -EINVAL;
        }
        echo_put_object(eco);
        RETURN(rc);
}

static int
echo_client_enqueue(struct obd_export *exp, struct obdo *oa,
                    int mode, obd_off offset, obd_size nob)
{
        struct echo_device     *ed = obd2echo_dev(exp->exp_obd);
        struct lustre_handle   *ulh = &oa->o_handle;
        struct echo_object     *eco;
        obd_off                 end;
        int                     rc;
        ENTRY;

        if (ed->ed_next == NULL)
                RETURN(-EOPNOTSUPP);

        if (!(mode == LCK_PR || mode == LCK_PW))
                RETURN(-EINVAL);

        if ((offset & (~CFS_PAGE_MASK)) != 0 ||
            (nob & (~CFS_PAGE_MASK)) != 0)
                RETURN(-EINVAL);

        rc = echo_get_object (&eco, ed, oa);
        if (rc != 0)
                RETURN(rc);

        end = (nob == 0) ? ((obd_off) -1) : (offset + nob - 1);
        rc = cl_echo_enqueue(eco, offset, end, mode, &ulh->cookie);
        if (rc == 0) {
                oa->o_valid |= OBD_MD_FLHANDLE;
                CDEBUG(D_INFO, "Cookie is "LPX64"\n", ulh->cookie);
        }
        echo_put_object(eco);
        RETURN(rc);
}

static int
echo_client_cancel(struct obd_export *exp, struct obdo *oa)
{
        struct echo_device *ed     = obd2echo_dev(exp->exp_obd);
        __u64               cookie = oa->o_handle.cookie;

        if ((oa->o_valid & OBD_MD_FLHANDLE) == 0)
                return -EINVAL;

        CDEBUG(D_INFO, "Cookie is "LPX64"\n", cookie);
        return cl_echo_cancel(ed, cookie);
}

static int
echo_client_iocontrol(unsigned int cmd, struct obd_export *exp,
                      int len, void *karg, void *uarg)
{
        struct obd_device      *obd = exp->exp_obd;
        struct echo_device     *ed = obd2echo_dev(obd);
        struct echo_client_obd *ec = ed->ed_ec;
        struct echo_object     *eco;
        struct obd_ioctl_data  *data = karg;
        struct obd_trans_info   dummy_oti;
        struct oti_req_ack_lock *ack_lock;
        struct obdo            *oa;
        struct lu_fid           fid;
        int                     rw = OBD_BRW_READ;
        int                     rc = 0;
        int                     i;
        ENTRY;

#ifndef HAVE_UNLOCKED_IOCTL
        cfs_unlock_kernel();
#endif

        memset(&dummy_oti, 0, sizeof(dummy_oti));

        oa = &data->ioc_obdo1;
        if (!(oa->o_valid & OBD_MD_FLGROUP)) {
                oa->o_valid |= OBD_MD_FLGROUP;
                oa->o_seq = FID_SEQ_ECHO;
        }

        /* This FID is unpacked just for validation at this point */
        rc = fid_ostid_unpack(&fid, &oa->o_oi, 0);
        if (rc < 0)
                RETURN(rc);

        switch (cmd) {
        case OBD_IOC_CREATE:                    /* may create echo object */
                if (!cfs_capable(CFS_CAP_SYS_ADMIN))
                        GOTO (out, rc = -EPERM);

                rc = echo_create_object (ed, 1, oa,
                                         data->ioc_pbuf1, data->ioc_plen1,
                                         &dummy_oti);
                GOTO(out, rc);

        case OBD_IOC_DESTROY:
                if (!cfs_capable(CFS_CAP_SYS_ADMIN))
                        GOTO (out, rc = -EPERM);

                rc = echo_get_object (&eco, ed, oa);
                if (rc == 0) {
                        rc = obd_destroy(ec->ec_exp, oa, eco->eo_lsm,
                                         &dummy_oti, NULL, NULL);
                        if (rc == 0)
                                eco->eo_deleted = 1;
                        echo_put_object(eco);
                }
                GOTO(out, rc);

        case OBD_IOC_GETATTR:
                rc = echo_get_object (&eco, ed, oa);
                if (rc == 0) {
                        struct obd_info oinfo = { { { 0 } } };
                        oinfo.oi_md = eco->eo_lsm;
                        oinfo.oi_oa = oa;
                        rc = obd_getattr(ec->ec_exp, &oinfo);
                        echo_put_object(eco);
                }
                GOTO(out, rc);

        case OBD_IOC_SETATTR:
                if (!cfs_capable(CFS_CAP_SYS_ADMIN))
                        GOTO (out, rc = -EPERM);

                rc = echo_get_object (&eco, ed, oa);
                if (rc == 0) {
                        struct obd_info oinfo = { { { 0 } } };
                        oinfo.oi_oa = oa;
                        oinfo.oi_md = eco->eo_lsm;

                        rc = obd_setattr(ec->ec_exp, &oinfo, NULL);
                        echo_put_object(eco);
                }
                GOTO(out, rc);

        case OBD_IOC_BRW_WRITE:
                if (!cfs_capable(CFS_CAP_SYS_ADMIN))
                        GOTO (out, rc = -EPERM);

                rw = OBD_BRW_WRITE;
                /* fall through */
        case OBD_IOC_BRW_READ:
                rc = echo_client_brw_ioctl(rw, exp, data);
                GOTO(out, rc);

        case ECHO_IOC_GET_STRIPE:
                rc = echo_get_object(&eco, ed, oa);
                if (rc == 0) {
                        rc = echo_copyout_lsm(eco->eo_lsm, data->ioc_pbuf1,
                                              data->ioc_plen1);
                        echo_put_object(eco);
                }
                GOTO(out, rc);

        case ECHO_IOC_SET_STRIPE:
                if (!cfs_capable(CFS_CAP_SYS_ADMIN))
                        GOTO (out, rc = -EPERM);

                if (data->ioc_pbuf1 == NULL) {  /* unset */
                        rc = echo_get_object(&eco, ed, oa);
                        if (rc == 0) {
                                eco->eo_deleted = 1;
                                echo_put_object(eco);
                        }
                } else {
                        rc = echo_create_object(ed, 0, oa,
                                                data->ioc_pbuf1,
                                                data->ioc_plen1, &dummy_oti);
                }
                GOTO (out, rc);

        case ECHO_IOC_ENQUEUE:
                if (!cfs_capable(CFS_CAP_SYS_ADMIN))
                        GOTO (out, rc = -EPERM);

                rc = echo_client_enqueue(exp, oa,
                                         data->ioc_conn1, /* lock mode */
                                         data->ioc_offset,
                                         data->ioc_count);/*extent*/
                GOTO (out, rc);

        case ECHO_IOC_CANCEL:
                rc = echo_client_cancel(exp, oa);
                GOTO (out, rc);

        default:
                CERROR ("echo_ioctl(): unrecognised ioctl %#x\n", cmd);
                GOTO (out, rc = -ENOTTY);
        }

        EXIT;
 out:

        /* XXX this should be in a helper also called by target_send_reply */
        for (ack_lock = dummy_oti.oti_ack_locks, i = 0; i < 4;
             i++, ack_lock++) {
                if (!ack_lock->mode)
                        break;
                ldlm_lock_decref(&ack_lock->lock, ack_lock->mode);
        }

#ifndef HAVE_UNLOCKED_IOCTL
        cfs_lock_kernel();
#endif

        return rc;
}

static int echo_client_setup(struct obd_device *obddev, struct lustre_cfg *lcfg)
{
        struct echo_client_obd *ec = &obddev->u.echo_client;
        struct obd_device *tgt;
        struct obd_uuid echo_uuid = { "ECHO_UUID" };
        struct obd_connect_data *ocd = NULL;
        int rc;
        ENTRY;

        if (lcfg->lcfg_bufcount < 2 || LUSTRE_CFG_BUFLEN(lcfg, 1) < 1) {
                CERROR("requires a TARGET OBD name\n");
                RETURN(-EINVAL);
        }

        tgt = class_name2obd(lustre_cfg_string(lcfg, 1));
        if (!tgt || !tgt->obd_attached || !tgt->obd_set_up) {
                CERROR("device not attached or not set up (%s)\n",
                       lustre_cfg_string(lcfg, 1));
                RETURN(-EINVAL);
        }

        cfs_spin_lock_init (&ec->ec_lock);
        CFS_INIT_LIST_HEAD (&ec->ec_objects);
        CFS_INIT_LIST_HEAD (&ec->ec_locks);
        ec->ec_unique = 0;
        ec->ec_nstripes = 0;

        OBD_ALLOC(ocd, sizeof(*ocd));
        if (ocd == NULL) {
                CERROR("Can't alloc ocd connecting to %s\n",
                       lustre_cfg_string(lcfg, 1));
                return -ENOMEM;
        }

        ocd->ocd_connect_flags = OBD_CONNECT_VERSION | OBD_CONNECT_REQPORTAL |
                                 OBD_CONNECT_GRANT | OBD_CONNECT_FULL20 |
                                 OBD_CONNECT_64BITHASH;
        ocd->ocd_version = LUSTRE_VERSION_CODE;
        ocd->ocd_group = FID_SEQ_ECHO;

        rc = obd_connect(NULL, &ec->ec_exp, tgt, &echo_uuid, ocd, NULL);
        if (rc == 0) {
                /* Turn off pinger because it connects to tgt obd directly. */
                cfs_spin_lock(&tgt->obd_dev_lock);
                cfs_list_del_init(&ec->ec_exp->exp_obd_chain_timed);
                cfs_spin_unlock(&tgt->obd_dev_lock);
        }

        OBD_FREE(ocd, sizeof(*ocd));

        if (rc != 0) {
                CERROR("fail to connect to device %s\n",
                       lustre_cfg_string(lcfg, 1));
                return (rc);
        }

        RETURN(rc);
}

static int echo_client_cleanup(struct obd_device *obddev)
{
        struct echo_client_obd *ec = &obddev->u.echo_client;
        int rc;
        ENTRY;

        if (!cfs_list_empty(&obddev->obd_exports)) {
                CERROR("still has clients!\n");
                RETURN(-EBUSY);
        }

        LASSERT(cfs_atomic_read(&ec->ec_exp->exp_refcount) > 0);
        rc = obd_disconnect(ec->ec_exp);
        if (rc != 0)
                CERROR("fail to disconnect device: %d\n", rc);

        RETURN(rc);
}

static int echo_client_connect(const struct lu_env *env,
                               struct obd_export **exp,
                               struct obd_device *src, struct obd_uuid *cluuid,
                               struct obd_connect_data *data, void *localdata)
{
        int                rc;
        struct lustre_handle conn = { 0 };

        ENTRY;
        rc = class_connect(&conn, src, cluuid);
        if (rc == 0) {
                *exp = class_conn2export(&conn);
        }

        RETURN (rc);
}

static int echo_client_disconnect(struct obd_export *exp)
{
#if 0
        struct obd_device      *obd;
        struct echo_client_obd *ec;
        struct ec_lock         *ecl;
#endif
        int                     rc;
        ENTRY;

        if (exp == NULL)
                GOTO(out, rc = -EINVAL);

#if 0
        obd = exp->exp_obd;
        ec = &obd->u.echo_client;

        /* no more contention on export's lock list */
        while (!cfs_list_empty (&exp->exp_ec_data.eced_locks)) {
                ecl = cfs_list_entry (exp->exp_ec_data.eced_locks.next,
                                      struct ec_lock, ecl_exp_chain);
                cfs_list_del (&ecl->ecl_exp_chain);

                rc = obd_cancel(ec->ec_exp, ecl->ecl_object->eco_lsm,
                                 ecl->ecl_mode, &ecl->ecl_lock_handle);

                CDEBUG (D_INFO, "Cancel lock on object "LPX64" on disconnect "
                        "(%d)\n", ecl->ecl_object->eco_id, rc);

                echo_put_object (ecl->ecl_object);
                OBD_FREE (ecl, sizeof (*ecl));
        }
#endif

        rc = class_disconnect(exp);
        GOTO(out, rc);
 out:
        return rc;
}

static struct obd_ops echo_obd_ops = {
        .o_owner       = THIS_MODULE,

#if 0
        .o_setup       = echo_client_setup,
        .o_cleanup     = echo_client_cleanup,
#endif

        .o_iocontrol   = echo_client_iocontrol,
        .o_connect     = echo_client_connect,
        .o_disconnect  = echo_client_disconnect
};

int echo_client_init(void)
{
        struct lprocfs_static_vars lvars = { 0 };
        int rc;

        lprocfs_echo_init_vars(&lvars);
        rc = class_register_type(&echo_obd_ops, NULL, lvars.module_vars,
                                 LUSTRE_ECHO_CLIENT_NAME, &echo_device_type);
        if (rc == 0)
                lu_kmem_init(echo_caches);
        return rc;
}

void echo_client_exit(void)
{
        class_unregister_type(LUSTRE_ECHO_CLIENT_NAME);
        lu_kmem_fini(echo_caches);
}

/** @} echo_client */