Merge tag 'hsi-for-3.16-fixes1' of git://git.kernel.org/pub/scm/linux/kernel/git...

[mirror_ubuntu-zesty-kernel.git] / drivers / staging / lustre / lustre / obdclass / cl_object.c

/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the 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) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * Client Lustre Object.
 *
 *   Author: Nikita Danilov <nikita.danilov@sun.com>
 */

/*
 * Locking.
 *
 *  i_mutex
 *      PG_locked
 *        ->coh_page_guard
 *        ->coh_lock_guard
 *        ->coh_attr_guard
 *        ->ls_guard
 */

#define DEBUG_SUBSYSTEM S_CLASS

#include <linux/libcfs/libcfs.h>
/* class_put_type() */
#include <obd_class.h>
#include <obd_support.h>
#include <lustre_fid.h>
#include <linux/list.h>
#include <linux/libcfs/libcfs_hash.h> /* for cfs_hash stuff */
#include <cl_object.h>
#include "cl_internal.h"

static struct kmem_cache *cl_env_kmem;

/** Lock class of cl_object_header::coh_page_guard */
static struct lock_class_key cl_page_guard_class;
/** Lock class of cl_object_header::coh_lock_guard */
static struct lock_class_key cl_lock_guard_class;
/** Lock class of cl_object_header::coh_attr_guard */
static struct lock_class_key cl_attr_guard_class;

extern __u32 lu_context_tags_default;
extern __u32 lu_session_tags_default;
/**
 * Initialize cl_object_header.
 */
int cl_object_header_init(struct cl_object_header *h)
{
        int result;

        result = lu_object_header_init(&h->coh_lu);
        if (result == 0) {
                spin_lock_init(&h->coh_page_guard);
                spin_lock_init(&h->coh_lock_guard);
                spin_lock_init(&h->coh_attr_guard);
                lockdep_set_class(&h->coh_page_guard, &cl_page_guard_class);
                lockdep_set_class(&h->coh_lock_guard, &cl_lock_guard_class);
                lockdep_set_class(&h->coh_attr_guard, &cl_attr_guard_class);
                h->coh_pages = 0;
                /* XXX hard coded GFP_* mask. */
                INIT_RADIX_TREE(&h->coh_tree, GFP_ATOMIC);
                INIT_LIST_HEAD(&h->coh_locks);
                h->coh_page_bufsize = ALIGN(sizeof(struct cl_page), 8);
        }
        return result;
}
EXPORT_SYMBOL(cl_object_header_init);

/**
 * Finalize cl_object_header.
 */
void cl_object_header_fini(struct cl_object_header *h)
{
        LASSERT(list_empty(&h->coh_locks));
        lu_object_header_fini(&h->coh_lu);
}
EXPORT_SYMBOL(cl_object_header_fini);

/**
 * Returns a cl_object with a given \a fid.
 *
 * Returns either cached or newly created object. Additional reference on the
 * returned object is acquired.
 *
 * \see lu_object_find(), cl_page_find(), cl_lock_find()
 */
struct cl_object *cl_object_find(const struct lu_env *env,
                                 struct cl_device *cd, const struct lu_fid *fid,
                                 const struct cl_object_conf *c)
{
        might_sleep();
        return lu2cl(lu_object_find_slice(env, cl2lu_dev(cd), fid, &c->coc_lu));
}
EXPORT_SYMBOL(cl_object_find);

/**
 * Releases a reference on \a o.
 *
 * When last reference is released object is returned to the cache, unless
 * lu_object_header_flags::LU_OBJECT_HEARD_BANSHEE bit is set in its header.
 *
 * \see cl_page_put(), cl_lock_put().
 */
void cl_object_put(const struct lu_env *env, struct cl_object *o)
{
        lu_object_put(env, &o->co_lu);
}
EXPORT_SYMBOL(cl_object_put);

/**
 * Acquire an additional reference to the object \a o.
 *
 * This can only be used to acquire _additional_ reference, i.e., caller
 * already has to possess at least one reference to \a o before calling this.
 *
 * \see cl_page_get(), cl_lock_get().
 */
void cl_object_get(struct cl_object *o)
{
        lu_object_get(&o->co_lu);
}
EXPORT_SYMBOL(cl_object_get);

/**
 * Returns the top-object for a given \a o.
 *
 * \see cl_page_top(), cl_io_top()
 */
struct cl_object *cl_object_top(struct cl_object *o)
{
        struct cl_object_header *hdr = cl_object_header(o);
        struct cl_object *top;

        while (hdr->coh_parent != NULL)
                hdr = hdr->coh_parent;

        top = lu2cl(lu_object_top(&hdr->coh_lu));
        CDEBUG(D_TRACE, "%p -> %p\n", o, top);
        return top;
}
EXPORT_SYMBOL(cl_object_top);

/**
 * Returns pointer to the lock protecting data-attributes for the given object
 * \a o.
 *
 * Data-attributes are protected by the cl_object_header::coh_attr_guard
 * spin-lock in the top-object.
 *
 * \see cl_attr, cl_object_attr_lock(), cl_object_operations::coo_attr_get().
 */
static spinlock_t *cl_object_attr_guard(struct cl_object *o)
{
        return &cl_object_header(cl_object_top(o))->coh_attr_guard;
}

/**
 * Locks data-attributes.
 *
 * Prevents data-attributes from changing, until lock is released by
 * cl_object_attr_unlock(). This has to be called before calls to
 * cl_object_attr_get(), cl_object_attr_set().
 */
void cl_object_attr_lock(struct cl_object *o)
{
        spin_lock(cl_object_attr_guard(o));
}
EXPORT_SYMBOL(cl_object_attr_lock);

/**
 * Releases data-attributes lock, acquired by cl_object_attr_lock().
 */
void cl_object_attr_unlock(struct cl_object *o)
{
        spin_unlock(cl_object_attr_guard(o));
}
EXPORT_SYMBOL(cl_object_attr_unlock);

/**
 * Returns data-attributes of an object \a obj.
 *
 * Every layer is asked (by calling cl_object_operations::coo_attr_get())
 * top-to-bottom to fill in parts of \a attr that this layer is responsible
 * for.
 */
int cl_object_attr_get(const struct lu_env *env, struct cl_object *obj,
                       struct cl_attr *attr)
{
        struct lu_object_header *top;
        int result;

        assert_spin_locked(cl_object_attr_guard(obj));

        top = obj->co_lu.lo_header;
        result = 0;
        list_for_each_entry(obj, &top->loh_layers, co_lu.lo_linkage) {
                if (obj->co_ops->coo_attr_get != NULL) {
                        result = obj->co_ops->coo_attr_get(env, obj, attr);
                        if (result != 0) {
                                if (result > 0)
                                        result = 0;
                                break;
                        }
                }
        }
        return result;
}
EXPORT_SYMBOL(cl_object_attr_get);

/**
 * Updates data-attributes of an object \a obj.
 *
 * Only attributes, mentioned in a validness bit-mask \a v are
 * updated. Calls cl_object_operations::coo_attr_set() on every layer, bottom
 * to top.
 */
int cl_object_attr_set(const struct lu_env *env, struct cl_object *obj,
                       const struct cl_attr *attr, unsigned v)
{
        struct lu_object_header *top;
        int result;

        assert_spin_locked(cl_object_attr_guard(obj));

        top = obj->co_lu.lo_header;
        result = 0;
        list_for_each_entry_reverse(obj, &top->loh_layers,
                                        co_lu.lo_linkage) {
                if (obj->co_ops->coo_attr_set != NULL) {
                        result = obj->co_ops->coo_attr_set(env, obj, attr, v);
                        if (result != 0) {
                                if (result > 0)
                                        result = 0;
                                break;
                        }
                }
        }
        return result;
}
EXPORT_SYMBOL(cl_object_attr_set);

/**
 * Notifies layers (bottom-to-top) that glimpse AST was received.
 *
 * Layers have to fill \a lvb fields with information that will be shipped
 * back to glimpse issuer.
 *
 * \see cl_lock_operations::clo_glimpse()
 */
int cl_object_glimpse(const struct lu_env *env, struct cl_object *obj,
                      struct ost_lvb *lvb)
{
        struct lu_object_header *top;
        int result;

        top = obj->co_lu.lo_header;
        result = 0;
        list_for_each_entry_reverse(obj, &top->loh_layers,
                                        co_lu.lo_linkage) {
                if (obj->co_ops->coo_glimpse != NULL) {
                        result = obj->co_ops->coo_glimpse(env, obj, lvb);
                        if (result != 0)
                                break;
                }
        }
        LU_OBJECT_HEADER(D_DLMTRACE, env, lu_object_top(top),
                         "size: "LPU64" mtime: "LPU64" atime: "LPU64" "
                         "ctime: "LPU64" blocks: "LPU64"\n",
                         lvb->lvb_size, lvb->lvb_mtime, lvb->lvb_atime,
                         lvb->lvb_ctime, lvb->lvb_blocks);
        return result;
}
EXPORT_SYMBOL(cl_object_glimpse);

/**
 * Updates a configuration of an object \a obj.
 */
int cl_conf_set(const struct lu_env *env, struct cl_object *obj,
                const struct cl_object_conf *conf)
{
        struct lu_object_header *top;
        int result;

        top = obj->co_lu.lo_header;
        result = 0;
        list_for_each_entry(obj, &top->loh_layers, co_lu.lo_linkage) {
                if (obj->co_ops->coo_conf_set != NULL) {
                        result = obj->co_ops->coo_conf_set(env, obj, conf);
                        if (result != 0)
                                break;
                }
        }
        return result;
}
EXPORT_SYMBOL(cl_conf_set);

/**
 * Helper function removing all object locks, and marking object for
 * deletion. All object pages must have been deleted at this point.
 *
 * This is called by cl_inode_fini() and lov_object_delete() to destroy top-
 * and sub- objects respectively.
 */
void cl_object_kill(const struct lu_env *env, struct cl_object *obj)
{
        struct cl_object_header *hdr;

        hdr = cl_object_header(obj);
        LASSERT(hdr->coh_tree.rnode == NULL);
        LASSERT(hdr->coh_pages == 0);

        set_bit(LU_OBJECT_HEARD_BANSHEE, &hdr->coh_lu.loh_flags);
        /*
         * Destroy all locks. Object destruction (including cl_inode_fini())
         * cannot cancel the locks, because in the case of a local client,
         * where client and server share the same thread running
         * prune_icache(), this can dead-lock with ldlm_cancel_handler()
         * waiting on __wait_on_freeing_inode().
         */
        cl_locks_prune(env, obj, 0);
}
EXPORT_SYMBOL(cl_object_kill);

/**
 * Prunes caches of pages and locks for this object.
 */
void cl_object_prune(const struct lu_env *env, struct cl_object *obj)
{
        cl_pages_prune(env, obj);
        cl_locks_prune(env, obj, 1);
}
EXPORT_SYMBOL(cl_object_prune);

/**
 * Check if the object has locks.
 */
int cl_object_has_locks(struct cl_object *obj)
{
        struct cl_object_header *head = cl_object_header(obj);
        int has;

        spin_lock(&head->coh_lock_guard);
        has = list_empty(&head->coh_locks);
        spin_unlock(&head->coh_lock_guard);

        return (has == 0);
}
EXPORT_SYMBOL(cl_object_has_locks);

void cache_stats_init(struct cache_stats *cs, const char *name)
{
        int i;

        cs->cs_name = name;
        for (i = 0; i < CS_NR; i++)
                atomic_set(&cs->cs_stats[i], 0);
}

int cache_stats_print(const struct cache_stats *cs, struct seq_file *m, int h)
{
        int i;
        /*
         *   lookup    hit    total  cached create
         * env: ...... ...... ...... ...... ......
         */
        if (h) {
                const char *names[CS_NR] = CS_NAMES;

                seq_printf(m, "%6s", " ");
                for (i = 0; i < CS_NR; i++)
                        seq_printf(m, "%8s", names[i]);
                seq_printf(m, "\n");
        }

        seq_printf(m, "%5.5s:", cs->cs_name);
        for (i = 0; i < CS_NR; i++)
                seq_printf(m, "%8u", atomic_read(&cs->cs_stats[i]));
        return 0;
}

/**
 * Initialize client site.
 *
 * Perform common initialization (lu_site_init()), and initialize statistical
 * counters. Also perform global initializations on the first call.
 */
int cl_site_init(struct cl_site *s, struct cl_device *d)
{
        int i;
        int result;

        result = lu_site_init(&s->cs_lu, &d->cd_lu_dev);
        if (result == 0) {
                cache_stats_init(&s->cs_pages, "pages");
                cache_stats_init(&s->cs_locks, "locks");
                for (i = 0; i < ARRAY_SIZE(s->cs_pages_state); ++i)
                        atomic_set(&s->cs_pages_state[0], 0);
                for (i = 0; i < ARRAY_SIZE(s->cs_locks_state); ++i)
                        atomic_set(&s->cs_locks_state[i], 0);
        }
        return result;
}
EXPORT_SYMBOL(cl_site_init);

/**
 * Finalize client site. Dual to cl_site_init().
 */
void cl_site_fini(struct cl_site *s)
{
        lu_site_fini(&s->cs_lu);
}
EXPORT_SYMBOL(cl_site_fini);

static struct cache_stats cl_env_stats = {
        .cs_name    = "envs",
        .cs_stats = { ATOMIC_INIT(0), }
};

/**
 * Outputs client site statistical counters into a buffer. Suitable for
 * ll_rd_*()-style functions.
 */
int cl_site_stats_print(const struct cl_site *site, struct seq_file *m)
{
        int i;
        static const char *pstate[] = {
                [CPS_CACHED]  = "c",
                [CPS_OWNED]   = "o",
                [CPS_PAGEOUT] = "w",
                [CPS_PAGEIN]  = "r",
                [CPS_FREEING] = "f"
        };
        static const char *lstate[] = {
                [CLS_NEW]       = "n",
                [CLS_QUEUING]   = "q",
                [CLS_ENQUEUED]  = "e",
                [CLS_HELD]      = "h",
                [CLS_INTRANSIT] = "t",
                [CLS_CACHED]    = "c",
                [CLS_FREEING]   = "f"
        };
/*
       lookup    hit  total   busy create
pages: ...... ...... ...... ...... ...... [...... ...... ...... ......]
locks: ...... ...... ...... ...... ...... [...... ...... ...... ...... ......]
  env: ...... ...... ...... ...... ......
 */
        lu_site_stats_print(&site->cs_lu, m);
        cache_stats_print(&site->cs_pages, m, 1);
        seq_printf(m, " [");
        for (i = 0; i < ARRAY_SIZE(site->cs_pages_state); ++i)
                seq_printf(m, "%s: %u ", pstate[i],
                                atomic_read(&site->cs_pages_state[i]));
        seq_printf(m, "]\n");
        cache_stats_print(&site->cs_locks, m, 0);
        seq_printf(m, " [");
        for (i = 0; i < ARRAY_SIZE(site->cs_locks_state); ++i)
                seq_printf(m, "%s: %u ", lstate[i],
                                atomic_read(&site->cs_locks_state[i]));
        seq_printf(m, "]\n");
        cache_stats_print(&cl_env_stats, m, 0);
        seq_printf(m, "\n");
        return 0;
}
EXPORT_SYMBOL(cl_site_stats_print);

/*****************************************************************************
 *
 * lu_env handling on client.
 *
 */

/**
 * The most efficient way is to store cl_env pointer in task specific
 * structures. On Linux, it wont' be easy to use task_struct->journal_info
 * because Lustre code may call into other fs which has certain assumptions
 * about journal_info. Currently following fields in task_struct are identified
 * can be used for this purpose:
 *  - cl_env: for liblustre.
 *  - tux_info: only on RedHat kernel.
 *  - ...
 * \note As long as we use task_struct to store cl_env, we assume that once
 * called into Lustre, we'll never call into the other part of the kernel
 * which will use those fields in task_struct without explicitly exiting
 * Lustre.
 *
 * If there's no space in task_struct is available, hash will be used.
 * bz20044, bz22683.
 */

struct cl_env {
        void         *ce_magic;
        struct lu_env     ce_lu;
        struct lu_context ce_ses;

        /**
         * This allows cl_env to be entered into cl_env_hash which implements
         * the current thread -> client environment lookup.
         */
        struct hlist_node  ce_node;
        /**
         * Owner for the current cl_env.
         *
         * If LL_TASK_CL_ENV is defined, this point to the owning current,
         * only for debugging purpose ;
         * Otherwise hash is used, and this is the key for cfs_hash.
         * Now current thread pid is stored. Note using thread pointer would
         * lead to unbalanced hash because of its specific allocation locality
         * and could be varied for different platforms and OSes, even different
         * OS versions.
         */
        void         *ce_owner;

        /*
         * Linkage into global list of all client environments. Used for
         * garbage collection.
         */
        struct list_head        ce_linkage;
        /*
         *
         */
        int            ce_ref;
        /*
         * Debugging field: address of the caller who made original
         * allocation.
         */
        void         *ce_debug;
};

#define CL_ENV_INC(counter)
#define CL_ENV_DEC(counter)

static void cl_env_init0(struct cl_env *cle, void *debug)
{
        LASSERT(cle->ce_ref == 0);
        LASSERT(cle->ce_magic == &cl_env_init0);
        LASSERT(cle->ce_debug == NULL && cle->ce_owner == NULL);

        cle->ce_ref = 1;
        cle->ce_debug = debug;
        CL_ENV_INC(busy);
}


/*
 * The implementation of using hash table to connect cl_env and thread
 */

static struct cfs_hash *cl_env_hash;

static unsigned cl_env_hops_hash(struct cfs_hash *lh,
                                 const void *key, unsigned mask)
{
#if BITS_PER_LONG == 64
        return cfs_hash_u64_hash((__u64)key, mask);
#else
        return cfs_hash_u32_hash((__u32)key, mask);
#endif
}

static void *cl_env_hops_obj(struct hlist_node *hn)
{
        struct cl_env *cle = hlist_entry(hn, struct cl_env, ce_node);
        LASSERT(cle->ce_magic == &cl_env_init0);
        return (void *)cle;
}

static int cl_env_hops_keycmp(const void *key, struct hlist_node *hn)
{
        struct cl_env *cle = cl_env_hops_obj(hn);

        LASSERT(cle->ce_owner != NULL);
        return (key == cle->ce_owner);
}

static void cl_env_hops_noop(struct cfs_hash *hs, struct hlist_node *hn)
{
        struct cl_env *cle = hlist_entry(hn, struct cl_env, ce_node);
        LASSERT(cle->ce_magic == &cl_env_init0);
}

static cfs_hash_ops_t cl_env_hops = {
        .hs_hash        = cl_env_hops_hash,
        .hs_key  = cl_env_hops_obj,
        .hs_keycmp      = cl_env_hops_keycmp,
        .hs_object      = cl_env_hops_obj,
        .hs_get  = cl_env_hops_noop,
        .hs_put_locked  = cl_env_hops_noop,
};

static inline struct cl_env *cl_env_fetch(void)
{
        struct cl_env *cle;

        cle = cfs_hash_lookup(cl_env_hash, (void *) (long) current->pid);
        LASSERT(ergo(cle, cle->ce_magic == &cl_env_init0));
        return cle;
}

static inline void cl_env_attach(struct cl_env *cle)
{
        if (cle) {
                int rc;

                LASSERT(cle->ce_owner == NULL);
                cle->ce_owner = (void *) (long) current->pid;
                rc = cfs_hash_add_unique(cl_env_hash, cle->ce_owner,
                                         &cle->ce_node);
                LASSERT(rc == 0);
        }
}

static inline void cl_env_do_detach(struct cl_env *cle)
{
        void *cookie;

        LASSERT(cle->ce_owner == (void *) (long) current->pid);
        cookie = cfs_hash_del(cl_env_hash, cle->ce_owner,
                              &cle->ce_node);
        LASSERT(cookie == cle);
        cle->ce_owner = NULL;
}

static int cl_env_store_init(void) {
        cl_env_hash = cfs_hash_create("cl_env",
                                      HASH_CL_ENV_BITS, HASH_CL_ENV_BITS,
                                      HASH_CL_ENV_BKT_BITS, 0,
                                      CFS_HASH_MIN_THETA,
                                      CFS_HASH_MAX_THETA,
                                      &cl_env_hops,
                                      CFS_HASH_RW_BKTLOCK);
        return cl_env_hash != NULL ? 0 :-ENOMEM;
}

static void cl_env_store_fini(void) {
        cfs_hash_putref(cl_env_hash);
}


static inline struct cl_env *cl_env_detach(struct cl_env *cle)
{
        if (cle == NULL)
                cle = cl_env_fetch();

        if (cle && cle->ce_owner)
                cl_env_do_detach(cle);

        return cle;
}

static struct lu_env *cl_env_new(__u32 ctx_tags, __u32 ses_tags, void *debug)
{
        struct lu_env *env;
        struct cl_env *cle;

        OBD_SLAB_ALLOC_PTR_GFP(cle, cl_env_kmem, GFP_NOFS);
        if (cle != NULL) {
                int rc;

                INIT_LIST_HEAD(&cle->ce_linkage);
                cle->ce_magic = &cl_env_init0;
                env = &cle->ce_lu;
                rc = lu_env_init(env, LCT_CL_THREAD|ctx_tags);
                if (rc == 0) {
                        rc = lu_context_init(&cle->ce_ses,
                                             LCT_SESSION | ses_tags);
                        if (rc == 0) {
                                lu_context_enter(&cle->ce_ses);
                                env->le_ses = &cle->ce_ses;
                                cl_env_init0(cle, debug);
                        } else
                                lu_env_fini(env);
                }
                if (rc != 0) {
                        OBD_SLAB_FREE_PTR(cle, cl_env_kmem);
                        env = ERR_PTR(rc);
                } else {
                        CL_ENV_INC(create);
                        CL_ENV_INC(total);
                }
        } else
                env = ERR_PTR(-ENOMEM);
        return env;
}

static void cl_env_fini(struct cl_env *cle)
{
        CL_ENV_DEC(total);
        lu_context_fini(&cle->ce_lu.le_ctx);
        lu_context_fini(&cle->ce_ses);
        OBD_SLAB_FREE_PTR(cle, cl_env_kmem);
}

static inline struct cl_env *cl_env_container(struct lu_env *env)
{
        return container_of(env, struct cl_env, ce_lu);
}

struct lu_env *cl_env_peek(int *refcheck)
{
        struct lu_env *env;
        struct cl_env *cle;

        CL_ENV_INC(lookup);

        /* check that we don't go far from untrusted pointer */
        CLASSERT(offsetof(struct cl_env, ce_magic) == 0);

        env = NULL;
        cle = cl_env_fetch();
        if (cle != NULL) {
                CL_ENV_INC(hit);
                env = &cle->ce_lu;
                *refcheck = ++cle->ce_ref;
        }
        CDEBUG(D_OTHER, "%d@%p\n", cle ? cle->ce_ref : 0, cle);
        return env;
}
EXPORT_SYMBOL(cl_env_peek);

/**
 * Returns lu_env: if there already is an environment associated with the
 * current thread, it is returned, otherwise, new environment is allocated.
 *
 * \param refcheck pointer to a counter used to detect environment leaks. In
 * the usual case cl_env_get() and cl_env_put() are called in the same lexical
 * scope and pointer to the same integer is passed as \a refcheck. This is
 * used to detect missed cl_env_put().
 *
 * \see cl_env_put()
 */
struct lu_env *cl_env_get(int *refcheck)
{
        struct lu_env *env;

        env = cl_env_peek(refcheck);
        if (env == NULL) {
                env = cl_env_new(lu_context_tags_default,
                                 lu_session_tags_default,
                                 __builtin_return_address(0));

                if (!IS_ERR(env)) {
                        struct cl_env *cle;

                        cle = cl_env_container(env);
                        cl_env_attach(cle);
                        *refcheck = cle->ce_ref;
                        CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
                }
        }
        return env;
}
EXPORT_SYMBOL(cl_env_get);

/**
 * Forces an allocation of a fresh environment with given tags.
 *
 * \see cl_env_get()
 */
struct lu_env *cl_env_alloc(int *refcheck, __u32 tags)
{
        struct lu_env *env;

        LASSERT(cl_env_peek(refcheck) == NULL);
        env = cl_env_new(tags, tags, __builtin_return_address(0));
        if (!IS_ERR(env)) {
                struct cl_env *cle;

                cle = cl_env_container(env);
                *refcheck = cle->ce_ref;
                CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
        }
        return env;
}
EXPORT_SYMBOL(cl_env_alloc);

static void cl_env_exit(struct cl_env *cle)
{
        LASSERT(cle->ce_owner == NULL);
        lu_context_exit(&cle->ce_lu.le_ctx);
        lu_context_exit(&cle->ce_ses);
}

/**
 * Release an environment.
 *
 * Decrement \a env reference counter. When counter drops to 0, nothing in
 * this thread is using environment and it is returned to the allocation
 * cache, or freed straight away, if cache is large enough.
 */
void cl_env_put(struct lu_env *env, int *refcheck)
{
        struct cl_env *cle;

        cle = cl_env_container(env);

        LASSERT(cle->ce_ref > 0);
        LASSERT(ergo(refcheck != NULL, cle->ce_ref == *refcheck));

        CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
        if (--cle->ce_ref == 0) {
                CL_ENV_DEC(busy);
                cl_env_detach(cle);
                cle->ce_debug = NULL;
                cl_env_exit(cle);
                cl_env_fini(cle);
        }
}
EXPORT_SYMBOL(cl_env_put);

/**
 * Declares a point of re-entrancy.
 *
 * \see cl_env_reexit()
 */
void *cl_env_reenter(void)
{
        return cl_env_detach(NULL);
}
EXPORT_SYMBOL(cl_env_reenter);

/**
 * Exits re-entrancy.
 */
void cl_env_reexit(void *cookie)
{
        cl_env_detach(NULL);
        cl_env_attach(cookie);
}
EXPORT_SYMBOL(cl_env_reexit);

/**
 * Setup user-supplied \a env as a current environment. This is to be used to
 * guaranteed that environment exists even when cl_env_get() fails. It is up
 * to user to ensure proper concurrency control.
 *
 * \see cl_env_unplant()
 */
void cl_env_implant(struct lu_env *env, int *refcheck)
{
        struct cl_env *cle = cl_env_container(env);

        LASSERT(cle->ce_ref > 0);

        cl_env_attach(cle);
        cl_env_get(refcheck);
        CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);
}
EXPORT_SYMBOL(cl_env_implant);

/**
 * Detach environment installed earlier by cl_env_implant().
 */
void cl_env_unplant(struct lu_env *env, int *refcheck)
{
        struct cl_env *cle = cl_env_container(env);

        LASSERT(cle->ce_ref > 1);

        CDEBUG(D_OTHER, "%d@%p\n", cle->ce_ref, cle);

        cl_env_detach(cle);
        cl_env_put(env, refcheck);
}
EXPORT_SYMBOL(cl_env_unplant);

struct lu_env *cl_env_nested_get(struct cl_env_nest *nest)
{
        struct lu_env *env;

        nest->cen_cookie = NULL;
        env = cl_env_peek(&nest->cen_refcheck);
        if (env != NULL) {
                if (!cl_io_is_going(env))
                        return env;
                else {
                        cl_env_put(env, &nest->cen_refcheck);
                        nest->cen_cookie = cl_env_reenter();
                }
        }
        env = cl_env_get(&nest->cen_refcheck);
        if (IS_ERR(env)) {
                cl_env_reexit(nest->cen_cookie);
                return env;
        }

        LASSERT(!cl_io_is_going(env));
        return env;
}
EXPORT_SYMBOL(cl_env_nested_get);

void cl_env_nested_put(struct cl_env_nest *nest, struct lu_env *env)
{
        cl_env_put(env, &nest->cen_refcheck);
        cl_env_reexit(nest->cen_cookie);
}
EXPORT_SYMBOL(cl_env_nested_put);

/**
 * Converts struct cl_attr to struct ost_lvb.
 *
 * \see cl_lvb2attr
 */
void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr)
{
        lvb->lvb_size   = attr->cat_size;
        lvb->lvb_mtime  = attr->cat_mtime;
        lvb->lvb_atime  = attr->cat_atime;
        lvb->lvb_ctime  = attr->cat_ctime;
        lvb->lvb_blocks = attr->cat_blocks;
}
EXPORT_SYMBOL(cl_attr2lvb);

/**
 * Converts struct ost_lvb to struct cl_attr.
 *
 * \see cl_attr2lvb
 */
void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb)
{
        attr->cat_size   = lvb->lvb_size;
        attr->cat_mtime  = lvb->lvb_mtime;
        attr->cat_atime  = lvb->lvb_atime;
        attr->cat_ctime  = lvb->lvb_ctime;
        attr->cat_blocks = lvb->lvb_blocks;
}
EXPORT_SYMBOL(cl_lvb2attr);

/*****************************************************************************
 *
 * Temporary prototype thing: mirror obd-devices into cl devices.
 *
 */

struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
                                struct lu_device_type *ldt,
                                struct lu_device *next)
{
        const char       *typename;
        struct lu_device *d;

        LASSERT(ldt != NULL);

        typename = ldt->ldt_name;
        d = ldt->ldt_ops->ldto_device_alloc(env, ldt, NULL);
        if (!IS_ERR(d)) {
                int rc;

                if (site != NULL)
                        d->ld_site = site;
                rc = ldt->ldt_ops->ldto_device_init(env, d, typename, next);
                if (rc == 0) {
                        lu_device_get(d);
                        lu_ref_add(&d->ld_reference,
                                   "lu-stack", &lu_site_init);
                } else {
                        ldt->ldt_ops->ldto_device_free(env, d);
                        CERROR("can't init device '%s', %d\n", typename, rc);
                        d = ERR_PTR(rc);
                }
        } else
                CERROR("Cannot allocate device: '%s'\n", typename);
        return lu2cl_dev(d);
}
EXPORT_SYMBOL(cl_type_setup);

/**
 * Finalize device stack by calling lu_stack_fini().
 */
void cl_stack_fini(const struct lu_env *env, struct cl_device *cl)
{
        lu_stack_fini(env, cl2lu_dev(cl));
}
EXPORT_SYMBOL(cl_stack_fini);

int  cl_lock_init(void);
void cl_lock_fini(void);

int  cl_page_init(void);
void cl_page_fini(void);

static struct lu_context_key cl_key;

struct cl_thread_info *cl_env_info(const struct lu_env *env)
{
        return lu_context_key_get(&env->le_ctx, &cl_key);
}

/* defines cl0_key_{init,fini}() */
LU_KEY_INIT_FINI(cl0, struct cl_thread_info);

static void *cl_key_init(const struct lu_context *ctx,
                         struct lu_context_key *key)
{
        struct cl_thread_info *info;

        info = cl0_key_init(ctx, key);
        if (!IS_ERR(info)) {
                int i;

                for (i = 0; i < ARRAY_SIZE(info->clt_counters); ++i)
                        lu_ref_init(&info->clt_counters[i].ctc_locks_locked);
        }
        return info;
}

static void cl_key_fini(const struct lu_context *ctx,
                        struct lu_context_key *key, void *data)
{
        struct cl_thread_info *info;
        int i;

        info = data;
        for (i = 0; i < ARRAY_SIZE(info->clt_counters); ++i)
                lu_ref_fini(&info->clt_counters[i].ctc_locks_locked);
        cl0_key_fini(ctx, key, data);
}

static void cl_key_exit(const struct lu_context *ctx,
                        struct lu_context_key *key, void *data)
{
        struct cl_thread_info *info = data;
        int i;

        for (i = 0; i < ARRAY_SIZE(info->clt_counters); ++i) {
                LASSERT(info->clt_counters[i].ctc_nr_held == 0);
                LASSERT(info->clt_counters[i].ctc_nr_used == 0);
                LASSERT(info->clt_counters[i].ctc_nr_locks_acquired == 0);
                LASSERT(info->clt_counters[i].ctc_nr_locks_locked == 0);
                lu_ref_fini(&info->clt_counters[i].ctc_locks_locked);
                lu_ref_init(&info->clt_counters[i].ctc_locks_locked);
        }
}

static struct lu_context_key cl_key = {
        .lct_tags = LCT_CL_THREAD,
        .lct_init = cl_key_init,
        .lct_fini = cl_key_fini,
        .lct_exit = cl_key_exit
};

static struct lu_kmem_descr cl_object_caches[] = {
        {
                .ckd_cache = &cl_env_kmem,
                .ckd_name  = "cl_env_kmem",
                .ckd_size  = sizeof (struct cl_env)
        },
        {
                .ckd_cache = NULL
        }
};

/**
 * Global initialization of cl-data. Create kmem caches, register
 * lu_context_key's, etc.
 *
 * \see cl_global_fini()
 */
int cl_global_init(void)
{
        int result;

        result = cl_env_store_init();
        if (result)
                return result;

        result = lu_kmem_init(cl_object_caches);
        if (result)
                goto out_store;

        LU_CONTEXT_KEY_INIT(&cl_key);
        result = lu_context_key_register(&cl_key);
        if (result)
                goto out_kmem;

        result = cl_lock_init();
        if (result)
                goto out_context;

        result = cl_page_init();
        if (result)
                goto out_lock;

        return 0;
out_lock:
        cl_lock_fini();
out_context:
        lu_context_key_degister(&cl_key);
out_kmem:
        lu_kmem_fini(cl_object_caches);
out_store:
        cl_env_store_fini();
        return result;
}

/**
 * Finalization of global cl-data. Dual to cl_global_init().
 */
void cl_global_fini(void)
{
        cl_lock_fini();
        cl_page_fini();
        lu_context_key_degister(&cl_key);
        lu_kmem_fini(cl_object_caches);
        cl_env_store_fini();
}