Merge tag 'iio-for-4.13b' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23...

[mirror_ubuntu-artful-kernel.git] / drivers / staging / lustre / lustre / obdecho / echo_client.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 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.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */

#define DEBUG_SUBSYSTEM S_ECHO
#include "../../include/linux/libcfs/libcfs.h"

#include "../include/obd.h"
#include "../include/obd_support.h"
#include "../include/obd_class.h"
#include "../include/lustre_debug.h"
#include "../include/lprocfs_status.h"
#include "../include/cl_object.h"
#include "../include/lustre_fid.h"
#include "../include/lustre_acl.h"
#include "../include/lustre/lustre_ioctl.h"
#include "../include/lustre_net.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 lu_site          *ed_site;
        struct lu_device       *ed_next;
};

struct echo_object {
        struct cl_object        eo_cl;
        struct cl_object_header eo_hdr;

        struct echo_device     *eo_dev;
        struct list_head              eo_obj_chain;
        struct lov_oinfo       *eo_oinfo;
        atomic_t            eo_npages;
        int                  eo_deleted;
};

struct echo_object_conf {
        struct cl_object_conf  eoc_cl;
        struct lov_oinfo      **eoc_oinfo;
};

struct echo_page {
        struct cl_page_slice   ep_cl;
        struct mutex            ep_lock;
};

struct echo_lock {
        struct cl_lock_slice   el_cl;
        struct list_head             el_chain;
        struct echo_object    *el_object;
        __u64             el_cookie;
        atomic_t           el_refcount;
};

static int echo_client_setup(const struct lu_env *env,
                             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);
        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);
}

/** @} echo_helpers */
static int cl_echo_object_put(struct echo_object *eco);
static int cl_echo_object_brw(struct echo_object *eco, int rw, u64 offset,
                              struct page **pages, int npages, int async);

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          eti_lock;
        struct lu_fid      eti_fid;
        struct lu_fid           eti_fid2;
};

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

static struct kmem_cache *echo_lock_kmem;
static struct kmem_cache *echo_object_kmem;
static struct kmem_cache *echo_thread_kmem;
static struct kmem_cache *echo_session_kmem;

static struct lu_kmem_descr echo_caches[] = {
        {
                .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)
        },
        {
                .ckd_cache = NULL
        }
};

/** \defgroup echo_page Page operations
 *
 * Echo page operations.
 *
 * @{
 */
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)
                mutex_lock(&ep->ep_lock);
        else if (!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(mutex_is_locked(&ep->ep_lock));
        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)
{
        if (mutex_is_locked(&cl2echo_page(slice)->ep_lock))
                return -EBUSY;
        return -ENODATA;
}

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);
}

static void echo_page_fini(const struct lu_env *env,
                           struct cl_page_slice *slice)
{
        struct echo_object *eco = cl2echo_obj(slice->cpl_obj);

        atomic_dec(&eco->eo_npages);
        put_page(slice->cpl_page->cp_vmpage);
}

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, mutex_is_locked(&ep->ep_lock),
                   slice->cpl_page->cp_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_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(list_empty(&ecl->el_chain));
        kmem_cache_free(echo_lock_kmem, ecl);
}

static struct cl_lock_operations echo_lock_ops = {
        .clo_fini      = echo_lock_fini,
};

/** @} echo_lock */

/** \defgroup echo_cl_ops cl_object operations
 *
 * operations for cl_object
 *
 * @{
 */
static int echo_page_init(const struct lu_env *env, struct cl_object *obj,
                          struct cl_page *page, pgoff_t index)
{
        struct echo_page *ep = cl_object_page_slice(obj, page);
        struct echo_object *eco = cl2echo_obj(obj);

        get_page(page->cp_vmpage);
        mutex_init(&ep->ep_lock);
        cl_page_slice_add(page, &ep->ep_cl, obj, index, &echo_page_ops);
        atomic_inc(&eco->eo_npages);
        return 0;
}

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;

        el = kmem_cache_zalloc(echo_lock_kmem, GFP_NOFS);
        if (el) {
                cl_lock_slice_add(lock, &el->el_cl, obj, &echo_lock_ops);
                el->el_object = cl2echo_obj(obj);
                INIT_LIST_HEAD(&el->el_chain);
                atomic_set(&el->el_refcount, 0);
        }
        return !el ? -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)
{
        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));
        const struct cl_object_conf *cconf;
        struct echo_object_conf *econf;

        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)
                        return -ENOMEM;
                lu_object_add(obj, below);
        }

        cconf = lu2cl_conf(conf);
        econf = cl2echo_conf(cconf);

        LASSERT(econf->eoc_oinfo);
        /*
         * Transfer the oinfo pointer to eco that it won't be
         * freed.
         */
        eco->eo_oinfo = *econf->eoc_oinfo;
        *econf->eoc_oinfo = NULL;

        eco->eo_dev = ed;
        atomic_set(&eco->eo_npages, 0);
        cl_object_page_init(lu2cl(obj), sizeof(struct echo_page));

        spin_lock(&ec->ec_lock);
        list_add_tail(&eco->eo_obj_chain, &ec->ec_objects);
        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;

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

        spin_lock(&ec->ec_lock);
        list_del_init(&eco->eo_obj_chain);
        spin_unlock(&ec->ec_lock);

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

        kfree(eco->eo_oinfo);
        kmem_cache_free(echo_object_kmem, eco);
}

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;

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

                obj = &echo_obj2cl(eco)->co_lu;
                cl_object_header_init(hdr);
                hdr->coh_page_bufsize = cfs_size_round(sizeof(struct cl_page));

                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 const struct lu_device_operations echo_device_lu_ops = {
        .ldo_object_alloc   = echo_object_alloc,
};

/** @} echo_lu_dev_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 initialize site for echo client(%d)\n", rc);
                return rc;
        }

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

        ed->ed_site = &site->cs_lu;
        return 0;
}

static void echo_site_fini(const struct lu_env *env, struct echo_device *ed)
{
        if (ed->ed_site) {
                lu_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;

        info = kmem_cache_zalloc(echo_thread_kmem, GFP_NOFS);
        if (!info)
                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;

        kmem_cache_free(echo_thread_kmem, info);
}

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,
};

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

        session = kmem_cache_zalloc(echo_session_kmem, GFP_NOFS);
        if (!session)
                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;

        kmem_cache_free(echo_session_kmem, session);
}

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

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, err;

        ed = kzalloc(sizeof(*ed), GFP_NOFS);
        if (!ed) {
                rc = -ENOMEM;
                goto out;
        }

        cd = &ed->ed_cl;
        rc = cl_device_init(cd, t);
        if (rc)
                goto out_free;

        cd->cd_lu_dev.ld_ops = &echo_device_lu_ops;

        obd = class_name2obd(lustre_cfg_string(cfg, 0));
        LASSERT(obd);
        LASSERT(env);

        tgt = class_name2obd(lustre_cfg_string(cfg, 1));
        if (!tgt) {
                CERROR("Can not find tgt device %s\n",
                       lustre_cfg_string(cfg, 1));
                rc = -ENODEV;
                goto out_device_fini;
        }

        next = tgt->obd_lu_dev;
        if (!strcmp(tgt->obd_type->typ_name, LUSTRE_MDT_NAME)) {
                CERROR("echo MDT client must be run on server\n");
                rc = -EOPNOTSUPP;
                goto out_device_fini;
        }

        rc = echo_site_init(env, ed);
        if (rc)
                goto out_device_fini;

        rc = echo_client_setup(env, obd, cfg);
        if (rc)
                goto out_site_fini;

        ed->ed_ec = &obd->u.echo_client;

        /* if echo client is to be stacked upon ost device, the next is
         * NULL since ost is not a clio device so far
         */
        if (next && !lu_device_is_cl(next))
                next = NULL;

        tgt_type_name = tgt->obd_type->typ_name;
        if (next) {
                if (next->ld_site) {
                        rc = -EBUSY;
                        goto out_cleanup;
                }

                next->ld_site = ed->ed_site;
                rc = next->ld_type->ldt_ops->ldto_device_init(env, next,
                                                next->ld_type->ldt_name,
                                                              NULL);
                if (rc)
                        goto out_cleanup;

        } else {
                LASSERT(strcmp(tgt_type_name, LUSTRE_OST_NAME) == 0);
        }

        ed->ed_next = next;
        return &cd->cd_lu_dev;

out_cleanup:
        err = echo_client_cleanup(obd);
        if (err)
                CERROR("Cleanup obd device %s error(%d)\n",
                       obd->obd_name, err);
out_site_fini:
        echo_site_fini(env, ed);
out_device_fini:
        cl_device_fini(&ed->ed_cl);
out_free:
        kfree(ed);
out:
        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_release(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);

        lu_site_purge(env, ed->ed_site, -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.
         */
        spin_lock(&ec->ec_lock);
        list_for_each_entry(eco, &ec->ec_objects, eo_obj_chain)
                eco->eo_deleted = 1;
        spin_unlock(&ec->ec_lock);

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

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

        /* Wait for the last reference to be dropped. */
        spin_lock(&ec->ec_lock);
        while (!list_empty(&ec->ec_objects)) {
                spin_unlock(&ec->ec_lock);
                CERROR("echo_client still has objects at cleanup time, wait for 1 second\n");
                set_current_state(TASK_UNINTERRUPTIBLE);
                schedule_timeout(cfs_time_seconds(1));
                lu_site_purge(env, ed->ed_site, -1);
                spin_lock(&ec->ec_lock);
        }
        spin_unlock(&ec->ec_lock);

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

        cl_env_cache_purge(~0);

        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, const struct ost_id *oi)
{
        struct lu_env *env;
        struct echo_thread_info *info;
        struct echo_object_conf *conf;
        struct lov_oinfo *oinfo = NULL;
        struct echo_object *eco;
        struct cl_object   *obj;
        struct lu_fid *fid;
        u16 refcheck;
        int rc;

        LASSERTF(ostid_id(oi), DOSTID "\n", POSTID(oi));
        LASSERTF(ostid_seq(oi) == FID_SEQ_ECHO, DOSTID "\n", POSTID(oi));

        /* 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) {
                oinfo = kzalloc(sizeof(*oinfo), GFP_NOFS);
                if (!oinfo) {
                        eco = ERR_PTR(-ENOMEM);
                        goto out;
                }

                oinfo->loi_oi = *oi;
                conf->eoc_cl.u.coc_oinfo = oinfo;
        }

        /*
         * If echo_object_init() is successful then ownership of oinfo
         * is transferred to the object.
         */
        conf->eoc_oinfo = &oinfo;

        fid  = &info->eti_fid;
        rc = ostid_to_fid(fid, (struct ost_id *)oi, 0);
        if (rc != 0) {
                eco = ERR_PTR(rc);
                goto out;
        }

        /* In the function below, .hs_keycmp resolves to
         * lu_obj_hop_keycmp()
         */
        /* coverity[overrun-buffer-val] */
        obj = cl_object_find(env, echo_dev2cl(d), fid, &conf->eoc_cl);
        if (IS_ERR(obj)) {
                eco = (void *)obj;
                goto out;
        }

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

out:
        kfree(oinfo);
        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);
        u16 refcheck;

        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));
                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,
                            u64 start, u64 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;

        info = echo_env_info(env);
        io = &info->eti_io;
        lck = &info->eti_lock;
        obj = echo_obj2cl(eco);

        memset(lck, 0, sizeof(*lck));
        descr = &lck->cll_descr;
        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;

        rc = cl_lock_request(env, io, lck);
        if (rc == 0) {
                struct echo_client_obd *ec = eco->eo_dev->ed_ec;
                struct echo_lock *el;

                el = cl2echo_lock(cl_lock_at(lck, &echo_device_type));
                spin_lock(&ec->ec_lock);
                if (list_empty(&el->el_chain)) {
                        list_add(&el->el_chain, &ec->ec_locks);
                        el->el_cookie = ++ec->ec_unique;
                }
                atomic_inc(&el->el_refcount);
                *cookie = el->el_cookie;
                spin_unlock(&ec->ec_lock);
        }
        return rc;
}

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;
        struct list_head             *el;
        int found = 0, still_used = 0;

        spin_lock(&ec->ec_lock);
        list_for_each(el, &ec->ec_locks) {
                ecl = list_entry(el, struct echo_lock, el_chain);
                CDEBUG(D_INFO, "ecl: %p, cookie: %#llx\n", ecl, ecl->el_cookie);
                found = (ecl->el_cookie == cookie);
                if (found) {
                        if (atomic_dec_and_test(&ecl->el_refcount))
                                list_del_init(&ecl->el_chain);
                        else
                                still_used = 1;
                        break;
                }
        }
        spin_unlock(&ec->ec_lock);

        if (!found)
                return -ENOENT;

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

static void echo_commit_callback(const struct lu_env *env, struct cl_io *io,
                                 struct cl_page *page)
{
        struct echo_thread_info *info;
        struct cl_2queue *queue;

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

        queue = &info->eti_queue;
        cl_page_list_add(&queue->c2_qout, page);
}

static int cl_echo_object_brw(struct echo_object *eco, int rw, u64 offset,
                              struct page **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 };
        size_t page_size = cl_page_size(obj);
        u16 refcheck;
        int rc;
        int i;

        LASSERT((offset & ~PAGE_MASK) == 0);
        LASSERT(ed->ed_next);
        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);

        io->ci_ignore_layout = 1;
        rc = cl_io_init(env, io, CIT_MISC, obj);
        if (rc < 0)
                goto out;
        LASSERT(rc == 0);

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

        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;
                }
                /*
                 * Add a page to the incoming page list of 2-queue.
                 */
                cl_page_list_add(&queue->c2_qin, 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_io_commit_async(env, io, &queue->c2_qin,
                                                0, PAGE_SIZE,
                                                echo_commit_callback);
                else
                        rc = cl_io_submit_sync(env, io, typ, queue, 0);
                CDEBUG(D_INFO, "echo_client %s write returns %d\n",
                       async ? "async" : "sync", rc);
        }

        cl_echo_cancel0(env, ed, lh.cookie);
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 u64 last_object_id;

static int echo_create_object(const struct lu_env *env, struct echo_device *ed,
                              struct obdo *oa)
{
        struct echo_object     *eco;
        struct echo_client_obd *ec = ed->ed_ec;
        int                  rc;
        int                  created = 0;

        if (!(oa->o_valid & OBD_MD_FLID) ||
            !(oa->o_valid & OBD_MD_FLGROUP) ||
            !fid_seq_is_echo(ostid_seq(&oa->o_oi))) {
                CERROR("invalid oid " DOSTID "\n", POSTID(&oa->o_oi));
                return -EINVAL;
        }

        if (!ostid_id(&oa->o_oi))
                ostid_set_id(&oa->o_oi, ++last_object_id);

        rc = obd_create(env, ec->ec_exp, oa);
        if (rc != 0) {
                CERROR("Cannot create objects: rc = %d\n", rc);
                goto failed;
        }
        created = 1;

        oa->o_valid |= OBD_MD_FLID;

        eco = cl_echo_object_find(ed, &oa->o_oi);
        if (IS_ERR(eco)) {
                rc = PTR_ERR(eco);
                goto failed;
        }
        cl_echo_object_put(eco);

        CDEBUG(D_INFO, "oa oid " DOSTID "\n", POSTID(&oa->o_oi));

 failed:
        if (created && rc)
                obd_destroy(env, ec->ec_exp, oa);
        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_object     *eco;
        int                  rc;

        if (!(oa->o_valid & OBD_MD_FLID) || !(oa->o_valid & OBD_MD_FLGROUP) ||
            !ostid_id(&oa->o_oi)) {
                CERROR("invalid oid " DOSTID "\n", POSTID(&oa->o_oi));
                return -EINVAL;
        }

        rc = 0;
        eco = cl_echo_object_find(ed, &oa->o_oi);
        if (!IS_ERR(eco))
                *ecop = eco;
        else
                rc = PTR_ERR(eco);
        return rc;
}

static void echo_put_object(struct echo_object *eco)
{
        int rc;

        rc = cl_echo_object_put(eco);
        if (rc)
                CERROR("%s: echo client drop an object failed: rc = %d\n",
                       eco->eo_dev->ed_ec->ec_exp->exp_obd->obd_name, rc);
}

static void
echo_client_page_debug_setup(struct page *page, int rw, u64 id,
                             u64 offset, u64 count)
{
        char    *addr;
        u64      stripe_off;
        u64      stripe_id;
        int      delta;

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

        addr = kmap(page);

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

        kunmap(page);
}

static int echo_client_page_debug_check(struct page *page, u64 id,
                                        u64 offset, u64 count)
{
        u64     stripe_off;
        u64     stripe_id;
        char   *addr;
        int     delta;
        int     rc;
        int     rc2;

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

        addr = kmap(page);

        for (rc = delta = 0; delta < PAGE_SIZE; delta += OBD_ECHO_BLOCK_SIZE) {
                stripe_off = offset + delta;
                stripe_id = 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 %#llx\n", id);
                        rc = rc2;
                }
        }

        kunmap(page);
        return rc;
}

static int echo_client_kbrw(struct echo_device *ed, int rw, struct obdo *oa,
                            struct echo_object *eco, u64 offset,
                            u64 count, int async)
{
        u32            npages;
        struct brw_page *pga;
        struct brw_page *pgp;
        struct page         **pages;
        u64              off;
        int                  i;
        int                  rc;
        int                  verify;
        gfp_t                gfp_mask;
        int                  brw_flags = 0;

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

        gfp_mask = ((ostid_id(&oa->o_oi) & 2) == 0) ? GFP_KERNEL : GFP_HIGHUSER;

        LASSERT(rw == OBD_BRW_WRITE || rw == OBD_BRW_READ);

        if (count <= 0 ||
            (count & (~PAGE_MASK)) != 0)
                return -EINVAL;

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

        if (rw == OBD_BRW_WRITE)
                brw_flags = OBD_BRW_ASYNC;

        pga = kcalloc(npages, sizeof(*pga), GFP_NOFS);
        if (!pga)
                return -ENOMEM;

        pages = kcalloc(npages, sizeof(*pages), GFP_NOFS);
        if (!pages) {
                kfree(pga);
                return -ENOMEM;
        }

        for (i = 0, pgp = pga, off = offset;
             i < npages;
             i++, pgp++, off += PAGE_SIZE) {
                LASSERT(!pgp->pg);      /* for cleanup */

                rc = -ENOMEM;
                pgp->pg = alloc_page(gfp_mask);
                if (!pgp->pg)
                        goto out;

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

                if (verify)
                        echo_client_page_debug_setup(pgp->pg, rw,
                                                     ostid_id(&oa->o_oi), off,
                                                     pgp->count);
        }

        /* brw mode can only be used at client */
        LASSERT(ed->ed_next);
        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)
                        continue;

                if (verify) {
                        int vrc;

                        vrc = echo_client_page_debug_check(pgp->pg,
                                                           ostid_id(&oa->o_oi),
                                                           pgp->off, pgp->count);
                        if (vrc != 0 && rc == 0)
                                rc = vrc;
                }
                __free_page(pgp->pg);
        }
        kfree(pga);
        kfree(pages);
        return rc;
}

static int echo_client_prep_commit(const struct lu_env *env,
                                   struct obd_export *exp, int rw,
                                   struct obdo *oa, struct echo_object *eco,
                                   u64 offset, u64 count,
                                   u64 batch, int async)
{
        struct obd_ioobj ioo;
        struct niobuf_local *lnb;
        struct niobuf_remote rnb;
        u64 off;
        u64 npages, tot_pages;
        int i, ret = 0, brw_flags = 0;

        if (count <= 0 || (count & (~PAGE_MASK)) != 0)
                return -EINVAL;

        npages = batch >> PAGE_SHIFT;
        tot_pages = count >> PAGE_SHIFT;

        lnb = kcalloc(npages, sizeof(struct niobuf_local), GFP_NOFS);
        if (!lnb) {
                ret = -ENOMEM;
                goto out;
        }

        if (rw == OBD_BRW_WRITE && async)
                brw_flags |= OBD_BRW_ASYNC;

        obdo_to_ioobj(oa, &ioo);

        off = offset;

        for (; tot_pages > 0; tot_pages -= npages) {
                int lpages;

                if (tot_pages < npages)
                        npages = tot_pages;

                rnb.rnb_offset = off;
                rnb.rnb_len = npages * PAGE_SIZE;
                rnb.rnb_flags = brw_flags;
                ioo.ioo_bufcnt = 1;
                off += npages * PAGE_SIZE;

                lpages = npages;
                ret = obd_preprw(env, rw, exp, oa, 1, &ioo, &rnb, &lpages, lnb);
                if (ret != 0)
                        goto out;

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

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

                        if (async)
                                lnb[i].lnb_flags |= OBD_BRW_ASYNC;

                        if (ostid_id(&oa->o_oi) == 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(page, rw,
                                                             ostid_id(&oa->o_oi),
                                                             lnb[i].lnb_file_offset,
                                                             lnb[i].lnb_len);
                        else
                                echo_client_page_debug_check(page,
                                                             ostid_id(&oa->o_oi),
                                                             lnb[i].lnb_file_offset,
                                                             lnb[i].lnb_len);
                }

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

                /* Reuse env context. */
                lu_context_exit((struct lu_context *)&env->le_ctx);
                lu_context_enter((struct lu_context *)&env->le_ctx);
        }

out:
        kfree(lnb);
        return ret;
}

static int echo_client_brw_ioctl(const struct lu_env *env, 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 obdo *oa = &data->ioc_obdo1;
        struct echo_object *eco;
        int rc;
        int async = 1;
        long test_mode;

        LASSERT(oa->o_valid & OBD_MD_FLGROUP);

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

        oa->o_valid &= ~OBD_MD_FLHANDLE;

        /* OFD/obdfilter works only via prep/commit */
        test_mode = (long)data->ioc_pbuf1;
        if (test_mode == 1)
                async = 0;

        if (!ed->ed_next && test_mode != 3) {
                test_mode = 3;
                data->ioc_plen1 = data->ioc_count;
        }

        /* Truncate batch size to maximum */
        if (data->ioc_plen1 > PTLRPC_MAX_BRW_SIZE)
                data->ioc_plen1 = PTLRPC_MAX_BRW_SIZE;

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

static int
echo_client_iocontrol(unsigned int cmd, struct obd_export *exp, int len,
                      void *karg, void __user *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 lu_env     *env;
        struct obdo         *oa;
        struct lu_fid      fid;
        int                  rw = OBD_BRW_READ;
        int                  rc = 0;

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

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

        env = kzalloc(sizeof(*env), GFP_NOFS);
        if (!env)
                return -ENOMEM;

        rc = lu_env_init(env, LCT_DT_THREAD);
        if (rc) {
                rc = -ENOMEM;
                goto out;
        }

        switch (cmd) {
        case OBD_IOC_CREATE:                /* may create echo object */
                if (!capable(CFS_CAP_SYS_ADMIN)) {
                        rc = -EPERM;
                        goto out;
                }

                rc = echo_create_object(env, ed, oa);
                goto out;

        case OBD_IOC_DESTROY:
                if (!capable(CFS_CAP_SYS_ADMIN)) {
                        rc = -EPERM;
                        goto out;
                }

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

        case OBD_IOC_GETATTR:
                rc = echo_get_object(&eco, ed, oa);
                if (rc == 0) {
                        rc = obd_getattr(env, ec->ec_exp, oa);
                        echo_put_object(eco);
                }
                goto out;

        case OBD_IOC_SETATTR:
                if (!capable(CFS_CAP_SYS_ADMIN)) {
                        rc = -EPERM;
                        goto out;
                }

                rc = echo_get_object(&eco, ed, oa);
                if (rc == 0) {
                        rc = obd_setattr(env, ec->ec_exp, oa);
                        echo_put_object(eco);
                }
                goto out;

        case OBD_IOC_BRW_WRITE:
                if (!capable(CFS_CAP_SYS_ADMIN)) {
                        rc = -EPERM;
                        goto out;
                }

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

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

out:
        lu_env_fini(env);
        kfree(env);

        return rc;
}

static int echo_client_setup(const struct lu_env *env,
                             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;

        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;
        }

        spin_lock_init(&ec->ec_lock);
        INIT_LIST_HEAD(&ec->ec_objects);
        INIT_LIST_HEAD(&ec->ec_locks);
        ec->ec_unique = 0;

        ocd = kzalloc(sizeof(*ocd), GFP_NOFS);
        if (!ocd)
                return -ENOMEM;

        ocd->ocd_connect_flags = OBD_CONNECT_VERSION | OBD_CONNECT_REQPORTAL |
                                 OBD_CONNECT_BRW_SIZE |
                                 OBD_CONNECT_GRANT | OBD_CONNECT_FULL20 |
                                 OBD_CONNECT_64BITHASH | OBD_CONNECT_LVB_TYPE |
                                 OBD_CONNECT_FID;
        ocd->ocd_brw_size = DT_MAX_BRW_SIZE;
        ocd->ocd_version = LUSTRE_VERSION_CODE;
        ocd->ocd_group = FID_SEQ_ECHO;

        rc = obd_connect(env, &ec->ec_exp, tgt, &echo_uuid, ocd, NULL);

        kfree(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;

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

        LASSERT(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 };

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

        return rc;
}

static int echo_client_disconnect(struct obd_export *exp)
{
        int                  rc;

        if (!exp) {
                rc = -EINVAL;
                goto out;
        }

        rc = class_disconnect(exp);
        goto out;
 out:
        return rc;
}

static struct obd_ops echo_client_obd_ops = {
        .owner          = THIS_MODULE,
        .iocontrol      = echo_client_iocontrol,
        .connect        = echo_client_connect,
        .disconnect     = echo_client_disconnect
};

static int echo_client_init(void)
{
        int rc;

        rc = lu_kmem_init(echo_caches);
        if (rc == 0) {
                rc = class_register_type(&echo_client_obd_ops, NULL,
                                         LUSTRE_ECHO_CLIENT_NAME,
                                         &echo_device_type);
                if (rc)
                        lu_kmem_fini(echo_caches);
        }
        return rc;
}

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

static int __init obdecho_init(void)
{
        LCONSOLE_INFO("Echo OBD driver; http://www.lustre.org/\n");

        LASSERT(PAGE_SIZE % OBD_ECHO_BLOCK_SIZE == 0);

        return echo_client_init();
}

static void /*__exit*/ obdecho_exit(void)
{
        echo_client_exit();
}

MODULE_AUTHOR("OpenSFS, Inc. <http://www.lustre.org/>");
MODULE_DESCRIPTION("Lustre Echo Client test driver");
MODULE_VERSION(LUSTRE_VERSION_STRING);
MODULE_LICENSE("GPL");

module_init(obdecho_init);
module_exit(obdecho_exit);

/** @} echo_client */