Whamcloud - gitweb
LU-2282 obdclass: Slightly increase the size of lu_keys[]
[fs/lustre-release.git] / lustre / obdclass / lu_object.c
index 72ae1cc..74c1cc9 100644 (file)
@@ -1,6 +1,4 @@
-/* -*- 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.
@@ -28,6 +26,8 @@
 /*
  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
+ *
+ * Copyright (c) 2011, 2012, Whamcloud, Inc.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -43,9 +43,6 @@
  */
 
 #define DEBUG_SUBSYSTEM S_CLASS
-#ifndef EXPORT_SYMTAB
-# define EXPORT_SYMTAB
-#endif
 
 #include <libcfs/libcfs.h>
 
@@ -73,64 +70,104 @@ static void lu_object_free(const struct lu_env *env, struct lu_object *o);
  */
 void lu_object_put(const struct lu_env *env, struct lu_object *o)
 {
+        struct lu_site_bkt_data *bkt;
         struct lu_object_header *top;
         struct lu_site          *site;
         struct lu_object        *orig;
-        int                      kill_it;
+        cfs_hash_bd_t            bd;
+       const struct lu_fid     *fid;
 
-        top = o->lo_header;
+        top  = o->lo_header;
         site = o->lo_dev->ld_site;
         orig = o;
-        kill_it = 0;
-        cfs_write_lock(&site->ls_guard);
-        if (cfs_atomic_dec_and_test(&top->loh_ref)) {
-                /*
-                 * When last reference is released, iterate over object
-                 * layers, and notify them that object is no longer busy.
-                 */
-                cfs_list_for_each_entry_reverse(o, &top->loh_layers,
-                                                lo_linkage) {
-                        if (o->lo_ops->loo_object_release != NULL)
-                                o->lo_ops->loo_object_release(env, o);
-                }
-                -- site->ls_busy;
+
+       /*
+        * till we have full fids-on-OST implemented anonymous objects
+        * are possible in OSP. such an object isn't listed in the site
+        * so we should not remove it from the site.
+        */
+       fid = lu_object_fid(o);
+       if (fid_is_zero(fid)) {
+               LASSERT(top->loh_hash.next == NULL
+                       && top->loh_hash.pprev == NULL);
+               LASSERT(cfs_list_empty(&top->loh_lru));
+               if (!cfs_atomic_dec_and_test(&top->loh_ref))
+                       return;
+               cfs_list_for_each_entry_reverse(o, &top->loh_layers, lo_linkage) {
+                       if (o->lo_ops->loo_object_release != NULL)
+                               o->lo_ops->loo_object_release(env, o);
+               }
+               lu_object_free(env, orig);
+               return;
+       }
+
+        cfs_hash_bd_get(site->ls_obj_hash, &top->loh_fid, &bd);
+        bkt = cfs_hash_bd_extra_get(site->ls_obj_hash, &bd);
+
+        if (!cfs_hash_bd_dec_and_lock(site->ls_obj_hash, &bd, &top->loh_ref)) {
                 if (lu_object_is_dying(top)) {
+
                         /*
-                         * If object is dying (will not be cached), removed it
-                         * from hash table and LRU.
-                         *
-                         * This is done with hash table and LRU lists
-                         * locked. As the only way to acquire first reference
-                         * to previously unreferenced object is through
-                         * hash-table lookup (lu_object_find()), or LRU
-                         * scanning (lu_site_purge()), that are done under
-                         * hash-table and LRU lock, no race with concurrent
-                         * object lookup is possible and we can safely destroy
-                         * object below.
+                         * somebody may be waiting for this, currently only
+                         * used for cl_object, see cl_object_put_last().
                          */
-                        cfs_hlist_del_init(&top->loh_hash);
-                        cfs_list_del_init(&top->loh_lru);
-                        -- site->ls_total;
-                        kill_it = 1;
+                        cfs_waitq_broadcast(&bkt->lsb_marche_funebre);
                 }
-        } else if (lu_object_is_dying(top)) {
-                /*
-                 * somebody may be waiting for this, currently only used
-                 * for cl_object, see cl_object_put_last().
-                 */
-                cfs_waitq_broadcast(&site->ls_marche_funebre);
+                return;
         }
-        cfs_write_unlock(&site->ls_guard);
-        if (kill_it)
-                /*
-                 * Object was already removed from hash and lru above, can
-                 * kill it.
-                 */
-                lu_object_free(env, orig);
+
+        LASSERT(bkt->lsb_busy > 0);
+        bkt->lsb_busy--;
+        /*
+         * When last reference is released, iterate over object
+         * layers, and notify them that object is no longer busy.
+         */
+        cfs_list_for_each_entry_reverse(o, &top->loh_layers, lo_linkage) {
+                if (o->lo_ops->loo_object_release != NULL)
+                        o->lo_ops->loo_object_release(env, o);
+        }
+
+        if (!lu_object_is_dying(top)) {
+                LASSERT(cfs_list_empty(&top->loh_lru));
+                cfs_list_add_tail(&top->loh_lru, &bkt->lsb_lru);
+                cfs_hash_bd_unlock(site->ls_obj_hash, &bd, 1);
+                return;
+        }
+
+        /*
+         * If object is dying (will not be cached), removed it
+         * from hash table and LRU.
+         *
+         * This is done with hash table and LRU lists locked. As the only
+         * way to acquire first reference to previously unreferenced
+         * object is through hash-table lookup (lu_object_find()),
+         * or LRU scanning (lu_site_purge()), that are done under hash-table
+         * and LRU lock, no race with concurrent object lookup is possible
+         * and we can safely destroy object below.
+         */
+        cfs_hash_bd_del_locked(site->ls_obj_hash, &bd, &top->loh_hash);
+        cfs_hash_bd_unlock(site->ls_obj_hash, &bd, 1);
+        /*
+         * Object was already removed from hash and lru above, can
+         * kill it.
+         */
+        lu_object_free(env, orig);
 }
 EXPORT_SYMBOL(lu_object_put);
 
 /**
+ * Put object and don't keep in cache. This is temporary solution for
+ * multi-site objects when its layering is not constant.
+ */
+void lu_object_put_nocache(const struct lu_env *env, struct lu_object *o)
+{
+       cfs_set_bit(LU_OBJECT_HEARD_BANSHEE,
+                   &o->lo_header->loh_flags);
+       return lu_object_put(env, o);
+}
+EXPORT_SYMBOL(lu_object_put_nocache);
+
+/**
  * Allocate new object.
  *
  * This follows object creation protocol, described in the comment within
@@ -160,7 +197,7 @@ static struct lu_object *lu_object_alloc(const struct lu_env *env,
          * after this point.
          */
         LASSERT(fid_is_igif(f) || fid_ver(f) == 0);
-        top->lo_header->loh_fid  = *f;
+        top->lo_header->loh_fid = *f;
         layers = &top->lo_header->loh_layers;
         do {
                 /*
@@ -192,7 +229,7 @@ static struct lu_object *lu_object_alloc(const struct lu_env *env,
                 }
         }
 
-        dev->ld_site->ls_stats.s_created ++;
+        lprocfs_counter_incr(dev->ld_site->ls_stats, LU_SS_CREATED);
         RETURN(top);
 }
 
@@ -201,13 +238,15 @@ static struct lu_object *lu_object_alloc(const struct lu_env *env,
  */
 static void lu_object_free(const struct lu_env *env, struct lu_object *o)
 {
-        cfs_list_t            splice;
-        struct lu_object     *scan;
-        struct lu_site       *site;
-        cfs_list_t           *layers;
+        struct lu_site_bkt_data *bkt;
+        struct lu_site          *site;
+        struct lu_object        *scan;
+        cfs_list_t              *layers;
+        cfs_list_t               splice;
 
         site   = o->lo_dev->ld_site;
         layers = &o->lo_header->loh_layers;
+        bkt    = lu_site_bkt_from_fid(site, &o->lo_header->loh_fid);
         /*
          * First call ->loo_object_delete() method to release all resources.
          */
@@ -235,7 +274,9 @@ static void lu_object_free(const struct lu_env *env, struct lu_object *o)
                 LASSERT(o->lo_ops->loo_object_free != NULL);
                 o->lo_ops->loo_object_free(env, o);
         }
-        cfs_waitq_broadcast(&site->ls_marche_funebre);
+
+        if (cfs_waitq_active(&bkt->lsb_marche_funebre))
+                cfs_waitq_broadcast(&bkt->lsb_marche_funebre);
 }
 
 /**
@@ -243,47 +284,78 @@ static void lu_object_free(const struct lu_env *env, struct lu_object *o)
  */
 int lu_site_purge(const struct lu_env *env, struct lu_site *s, int nr)
 {
-        cfs_list_t               dispose;
         struct lu_object_header *h;
         struct lu_object_header *temp;
+        struct lu_site_bkt_data *bkt;
+        cfs_hash_bd_t            bd;
+        cfs_hash_bd_t            bd2;
+        cfs_list_t               dispose;
+        int                      did_sth;
+        int                      start;
+        int                      count;
+        int                      bnr;
+        int                      i;
 
         CFS_INIT_LIST_HEAD(&dispose);
         /*
          * Under LRU list lock, scan LRU list and move unreferenced objects to
          * the dispose list, removing them from LRU and hash table.
          */
-        cfs_write_lock(&s->ls_guard);
-        cfs_list_for_each_entry_safe(h, temp, &s->ls_lru, loh_lru) {
+        start = s->ls_purge_start;
+        bnr = (nr == ~0) ? -1 : nr / CFS_HASH_NBKT(s->ls_obj_hash) + 1;
+ again:
+        did_sth = 0;
+        cfs_hash_for_each_bucket(s->ls_obj_hash, &bd, i) {
+                if (i < start)
+                        continue;
+                count = bnr;
+                cfs_hash_bd_lock(s->ls_obj_hash, &bd, 1);
+                bkt = cfs_hash_bd_extra_get(s->ls_obj_hash, &bd);
+
+                cfs_list_for_each_entry_safe(h, temp, &bkt->lsb_lru, loh_lru) {
+                        LASSERT(cfs_atomic_read(&h->loh_ref) == 0);
+
+                        cfs_hash_bd_get(s->ls_obj_hash, &h->loh_fid, &bd2);
+                        LASSERT(bd.bd_bucket == bd2.bd_bucket);
+
+                        cfs_hash_bd_del_locked(s->ls_obj_hash,
+                                               &bd2, &h->loh_hash);
+                        cfs_list_move(&h->loh_lru, &dispose);
+                        if (did_sth == 0)
+                                did_sth = 1;
+
+                        if (nr != ~0 && --nr == 0)
+                                break;
+
+                        if (count > 0 && --count == 0)
+                                break;
+
+                }
+                cfs_hash_bd_unlock(s->ls_obj_hash, &bd, 1);
+                cfs_cond_resched();
                 /*
-                 * Objects are sorted in lru order, and "busy" objects (ones
-                 * with h->loh_ref > 0) naturally tend to live near hot end
-                 * that we scan last. Unfortunately, sites usually have small
-                 * (less then ten) number of busy yet rarely accessed objects
-                 * (some global objects, accessed directly through pointers,
-                 * bypassing hash table). Currently algorithm scans them over
-                 * and over again. Probably we should move busy objects out of
-                 * LRU, or we can live with that.
+                 * Free everything on the dispose list. This is safe against
+                 * races due to the reasons described in lu_object_put().
                  */
-                if (nr-- == 0)
+                while (!cfs_list_empty(&dispose)) {
+                        h = container_of0(dispose.next,
+                                          struct lu_object_header, loh_lru);
+                        cfs_list_del_init(&h->loh_lru);
+                        lu_object_free(env, lu_object_top(h));
+                        lprocfs_counter_incr(s->ls_stats, LU_SS_LRU_PURGED);
+                }
+
+                if (nr == 0)
                         break;
-                if (cfs_atomic_read(&h->loh_ref) > 0)
-                        continue;
-                cfs_hlist_del_init(&h->loh_hash);
-                cfs_list_move(&h->loh_lru, &dispose);
-                s->ls_total --;
         }
-        cfs_write_unlock(&s->ls_guard);
-        /*
-         * Free everything on the dispose list. This is safe against races due
-         * to the reasons described in lu_object_put().
-         */
-        while (!cfs_list_empty(&dispose)) {
-                h = container_of0(dispose.next,
-                                 struct lu_object_header, loh_lru);
-                cfs_list_del_init(&h->loh_lru);
-                lu_object_free(env, lu_object_top(h));
-                s->ls_stats.s_lru_purged ++;
+
+        if (nr != 0 && did_sth && start != 0) {
+                start = 0; /* restart from the first bucket */
+                goto again;
         }
+        /* race on s->ls_purge_start, but nobody cares */
+        s->ls_purge_start = i % CFS_HASH_NBKT(s->ls_obj_hash);
+
         return nr;
 }
 EXPORT_SYMBOL(lu_site_purge);
@@ -310,7 +382,7 @@ enum {
          *
          * XXX overflow is not handled correctly.
          */
-        LU_CDEBUG_LINE = 256
+        LU_CDEBUG_LINE = 512
 };
 
 struct lu_cdebug_data {
@@ -328,7 +400,8 @@ LU_KEY_INIT_FINI(lu_global, struct lu_cdebug_data);
  * lu_global_init().
  */
 struct lu_context_key lu_global_key = {
-        .lct_tags = LCT_MD_THREAD|LCT_DT_THREAD|LCT_CL_THREAD,
+        .lct_tags = LCT_MD_THREAD | LCT_DT_THREAD |
+                    LCT_MG_THREAD | LCT_CL_THREAD,
         .lct_init = lu_global_key_init,
         .lct_fini = lu_global_key_fini
 };
@@ -339,8 +412,8 @@ struct lu_context_key lu_global_key = {
 int lu_cdebug_printer(const struct lu_env *env,
                       void *cookie, const char *format, ...)
 {
-        struct lu_cdebug_print_info *info = cookie;
-        struct lu_cdebug_data       *key;
+        struct libcfs_debug_msg_data *msgdata = cookie;
+        struct lu_cdebug_data        *key;
         int used;
         int complete;
         va_list args;
@@ -358,10 +431,8 @@ int lu_cdebug_printer(const struct lu_env *env,
         vsnprintf(key->lck_area + used,
                   ARRAY_SIZE(key->lck_area) - used, format, args);
         if (complete) {
-                if (cfs_cdebug_show(info->lpi_mask, info->lpi_subsys))
-                        libcfs_debug_msg(NULL, info->lpi_subsys, info->lpi_mask,
-                                         (char *)info->lpi_file, info->lpi_fn,
-                                         info->lpi_line, "%s", key->lck_area);
+                if (cfs_cdebug_show(msgdata->msg_mask, msgdata->msg_subsys))
+                        libcfs_debug_msg(msgdata, "%s", key->lck_area);
                 key->lck_area[0] = 0;
         }
         va_end(args);
@@ -433,52 +504,48 @@ int lu_object_invariant(const struct lu_object *o)
 EXPORT_SYMBOL(lu_object_invariant);
 
 static struct lu_object *htable_lookup(struct lu_site *s,
-                                       const cfs_hlist_head_t *bucket,
+                                       cfs_hash_bd_t *bd,
                                        const struct lu_fid *f,
-                                       cfs_waitlink_t *waiter)
+                                       cfs_waitlink_t *waiter,
+                                       __u64 *version)
 {
+        struct lu_site_bkt_data *bkt;
         struct lu_object_header *h;
-        cfs_hlist_node_t *scan;
-
-        cfs_hlist_for_each_entry(h, scan, bucket, loh_hash) {
-                s->ls_stats.s_cache_check ++;
-                if (likely(lu_fid_eq(&h->loh_fid, f))) {
-                        if (unlikely(lu_object_is_dying(h))) {
-                                /*
-                                 * Lookup found an object being destroyed;
-                                 * this object cannot be returned (to assure
-                                 * that references to dying objects are
-                                 * eventually drained), and moreover, lookup
-                                 * has to wait until object is freed.
-                                 */
-                                cfs_waitlink_init(waiter);
-                                cfs_waitq_add(&s->ls_marche_funebre, waiter);
-                                cfs_set_current_state(CFS_TASK_UNINT);
-                                s->ls_stats.s_cache_death_race ++;
-                                return ERR_PTR(-EAGAIN);
-                        }
-                        /* bump reference count... */
-                        if (cfs_atomic_add_return(1, &h->loh_ref) == 1)
-                                ++ s->ls_busy;
-                        /* and move to the head of the LRU */
-                        /*
-                         * XXX temporary disable this to measure effects of
-                         * read-write locking.
-                         */
-                        /* list_move_tail(&h->loh_lru, &s->ls_lru); */
-                        s->ls_stats.s_cache_hit ++;
-                        return lu_object_top(h);
-                }
+        cfs_hlist_node_t        *hnode;
+        __u64  ver = cfs_hash_bd_version_get(bd);
+
+        if (*version == ver)
+                return NULL;
+
+        *version = ver;
+        bkt = cfs_hash_bd_extra_get(s->ls_obj_hash, bd);
+        /* cfs_hash_bd_lookup_intent is a somehow "internal" function
+         * of cfs_hash, but we don't want refcount on object right now */
+        hnode = cfs_hash_bd_lookup_locked(s->ls_obj_hash, bd, (void *)f);
+        if (hnode == NULL) {
+                lprocfs_counter_incr(s->ls_stats, LU_SS_CACHE_MISS);
+                return NULL;
         }
-        s->ls_stats.s_cache_miss ++;
-        return NULL;
-}
 
-static __u32 fid_hash(const struct lu_fid *f, int bits)
-{
-        /* all objects with same id and different versions will belong to same
-         * collisions list. */
-        return cfs_hash_long(fid_flatten(f), bits);
+        h = container_of0(hnode, struct lu_object_header, loh_hash);
+        if (likely(!lu_object_is_dying(h))) {
+                lprocfs_counter_incr(s->ls_stats, LU_SS_CACHE_HIT);
+                cfs_list_del_init(&h->loh_lru);
+                return lu_object_top(h);
+        }
+
+        /*
+         * Lookup found an object being destroyed this object cannot be
+         * returned (to assure that references to dying objects are eventually
+         * drained), and moreover, lookup has to wait until object is freed.
+         */
+        cfs_atomic_dec(&h->loh_ref);
+
+        cfs_waitlink_init(waiter);
+        cfs_waitq_add(&bkt->lsb_marche_funebre, waiter);
+        cfs_set_current_state(CFS_TASK_UNINT);
+        lprocfs_counter_incr(s->ls_stats, LU_SS_CACHE_DEATH_RACE);
+        return ERR_PTR(-EAGAIN);
 }
 
 /**
@@ -494,6 +561,29 @@ struct lu_object *lu_object_find(const struct lu_env *env,
 }
 EXPORT_SYMBOL(lu_object_find);
 
+static struct lu_object *lu_object_new(const struct lu_env *env,
+                                       struct lu_device *dev,
+                                       const struct lu_fid *f,
+                                       const struct lu_object_conf *conf)
+{
+        struct lu_object        *o;
+        cfs_hash_t              *hs;
+        cfs_hash_bd_t            bd;
+        struct lu_site_bkt_data *bkt;
+
+        o = lu_object_alloc(env, dev, f, conf);
+        if (unlikely(IS_ERR(o)))
+                return o;
+
+        hs = dev->ld_site->ls_obj_hash;
+        cfs_hash_bd_get_and_lock(hs, (void *)f, &bd, 1);
+        bkt = cfs_hash_bd_extra_get(hs, &bd);
+        cfs_hash_bd_add_locked(hs, &bd, &o->lo_header->loh_hash);
+        bkt->lsb_busy++;
+        cfs_hash_bd_unlock(hs, &bd, 1);
+        return o;
+}
+
 /**
  * Core logic of lu_object_find*() functions.
  */
@@ -503,10 +593,12 @@ static struct lu_object *lu_object_find_try(const struct lu_env *env,
                                             const struct lu_object_conf *conf,
                                             cfs_waitlink_t *waiter)
 {
-        struct lu_site        *s;
         struct lu_object      *o;
         struct lu_object      *shadow;
-        cfs_hlist_head_t      *bucket;
+        struct lu_site        *s;
+        cfs_hash_t            *hs;
+        cfs_hash_bd_t          bd;
+        __u64                  version = 0;
 
         /*
          * This uses standard index maintenance protocol:
@@ -521,17 +613,21 @@ static struct lu_object *lu_object_find_try(const struct lu_env *env,
          *     - unlock index;
          *     - return object.
          *
+         * For "LOC_F_NEW" case, we are sure the object is new established.
+         * It is unnecessary to perform lookup-alloc-lookup-insert, instead,
+         * just alloc and insert directly.
+         *
          * If dying object is found during index search, add @waiter to the
          * site wait-queue and return ERR_PTR(-EAGAIN).
          */
-
-        s = dev->ld_site;
-        bucket = s->ls_hash + fid_hash(f, s->ls_hash_bits);
-
-        cfs_read_lock(&s->ls_guard);
-        o = htable_lookup(s, bucket, f, waiter);
-        cfs_read_unlock(&s->ls_guard);
-
+        if (conf != NULL && conf->loc_flags & LOC_F_NEW)
+                return lu_object_new(env, dev, f, conf);
+
+        s  = dev->ld_site;
+        hs = s->ls_obj_hash;
+        cfs_hash_bd_get_and_lock(hs, (void *)f, &bd, 1);
+        o = htable_lookup(s, &bd, f, waiter, &version);
+        cfs_hash_bd_unlock(hs, &bd, 1);
         if (o != NULL)
                 return o;
 
@@ -545,20 +641,22 @@ static struct lu_object *lu_object_find_try(const struct lu_env *env,
 
         LASSERT(lu_fid_eq(lu_object_fid(o), f));
 
-        cfs_write_lock(&s->ls_guard);
-        shadow = htable_lookup(s, bucket, f, waiter);
+        cfs_hash_bd_lock(hs, &bd, 1);
+
+        shadow = htable_lookup(s, &bd, f, waiter, &version);
         if (likely(shadow == NULL)) {
-                cfs_hlist_add_head(&o->lo_header->loh_hash, bucket);
-                cfs_list_add_tail(&o->lo_header->loh_lru, &s->ls_lru);
-                ++ s->ls_busy;
-                ++ s->ls_total;
-                shadow = o;
-                o = NULL;
-        } else
-                s->ls_stats.s_cache_race ++;
-        cfs_write_unlock(&s->ls_guard);
-        if (o != NULL)
-                lu_object_free(env, o);
+                struct lu_site_bkt_data *bkt;
+
+                bkt = cfs_hash_bd_extra_get(hs, &bd);
+                cfs_hash_bd_add_locked(hs, &bd, &o->lo_header->loh_hash);
+                bkt->lsb_busy++;
+                cfs_hash_bd_unlock(hs, &bd, 1);
+                return o;
+        }
+
+        lprocfs_counter_incr(s->ls_stats, LU_SS_CACHE_RACE);
+        cfs_hash_bd_unlock(hs, &bd, 1);
+        lu_object_free(env, o);
         return shadow;
 }
 
@@ -572,22 +670,22 @@ struct lu_object *lu_object_find_at(const struct lu_env *env,
                                     const struct lu_fid *f,
                                     const struct lu_object_conf *conf)
 {
-        struct lu_object *obj;
-        cfs_waitlink_t    wait;
+        struct lu_site_bkt_data *bkt;
+        struct lu_object        *obj;
+        cfs_waitlink_t           wait;
 
         while (1) {
                 obj = lu_object_find_try(env, dev, f, conf, &wait);
-                if (obj == ERR_PTR(-EAGAIN)) {
-                        /*
-                         * lu_object_find_try() already added waiter into the
-                         * wait queue.
-                         */
-                        cfs_waitq_wait(&wait, CFS_TASK_UNINT);
-                        cfs_waitq_del(&dev->ld_site->ls_marche_funebre, &wait);
-                } else
-                        break;
+                if (obj != ERR_PTR(-EAGAIN))
+                        return obj;
+                /*
+                 * lu_object_find_try() already added waiter into the
+                 * wait queue.
+                 */
+                cfs_waitq_wait(&wait, CFS_TASK_UNINT);
+                bkt = lu_site_bkt_from_fid(dev->ld_site, (void *)f);
+                cfs_waitq_del(&bkt->lsb_marche_funebre, &wait);
         }
-        return obj;
 }
 EXPORT_SYMBOL(lu_object_find_at);
 
@@ -652,45 +750,65 @@ EXPORT_SYMBOL(lu_types_stop);
  * Global list of all sites on this node
  */
 static CFS_LIST_HEAD(lu_sites);
-static CFS_DECLARE_MUTEX(lu_sites_guard);
+static CFS_DEFINE_MUTEX(lu_sites_guard);
 
 /**
  * Global environment used by site shrinker.
  */
 static struct lu_env lu_shrink_env;
 
+struct lu_site_print_arg {
+        struct lu_env   *lsp_env;
+        void            *lsp_cookie;
+        lu_printer_t     lsp_printer;
+};
+
+static int
+lu_site_obj_print(cfs_hash_t *hs, cfs_hash_bd_t *bd,
+                  cfs_hlist_node_t *hnode, void *data)
+{
+        struct lu_site_print_arg *arg = (struct lu_site_print_arg *)data;
+        struct lu_object_header  *h;
+
+        h = cfs_hlist_entry(hnode, struct lu_object_header, loh_hash);
+        if (!cfs_list_empty(&h->loh_layers)) {
+                const struct lu_object *o;
+
+                o = lu_object_top(h);
+                lu_object_print(arg->lsp_env, arg->lsp_cookie,
+                                arg->lsp_printer, o);
+        } else {
+                lu_object_header_print(arg->lsp_env, arg->lsp_cookie,
+                                       arg->lsp_printer, h);
+        }
+        return 0;
+}
+
 /**
  * Print all objects in \a s.
  */
 void lu_site_print(const struct lu_env *env, struct lu_site *s, void *cookie,
                    lu_printer_t printer)
 {
-        int i;
-
-        for (i = 0; i < s->ls_hash_size; ++i) {
-                struct lu_object_header *h;
-                cfs_hlist_node_t        *scan;
-
-                cfs_read_lock(&s->ls_guard);
-                cfs_hlist_for_each_entry(h, scan, &s->ls_hash[i], loh_hash) {
-
-                        if (!cfs_list_empty(&h->loh_layers)) {
-                                const struct lu_object *obj;
+        struct lu_site_print_arg arg = {
+                .lsp_env     = (struct lu_env *)env,
+                .lsp_cookie  = cookie,
+                .lsp_printer = printer,
+        };
 
-                                obj = lu_object_top(h);
-                                lu_object_print(env, cookie, printer, obj);
-                        } else
-                                lu_object_header_print(env, cookie, printer, h);
-                }
-                cfs_read_unlock(&s->ls_guard);
-        }
+        cfs_hash_for_each(s->ls_obj_hash, lu_site_obj_print, &arg);
 }
 EXPORT_SYMBOL(lu_site_print);
 
 enum {
-        LU_CACHE_PERCENT   = 20,
+        LU_CACHE_PERCENT_MAX     = 50,
+        LU_CACHE_PERCENT_DEFAULT = 20
 };
 
+static unsigned int lu_cache_percent = LU_CACHE_PERCENT_DEFAULT;
+CFS_MODULE_PARM(lu_cache_percent, "i", int, 0644,
+                "Percentage of memory to be used as lu_object cache");
+
 /**
  * Return desired hash table order.
  */
@@ -714,7 +832,16 @@ static int lu_htable_order(void)
                 cache_size = 1 << (30 - CFS_PAGE_SHIFT) * 3 / 4;
 #endif
 
-        cache_size = cache_size / 100 * LU_CACHE_PERCENT *
+        /* clear off unreasonable cache setting. */
+        if (lu_cache_percent == 0 || lu_cache_percent > LU_CACHE_PERCENT_MAX) {
+                CWARN("obdclass: invalid lu_cache_percent: %u, it must be in"
+                      " the range of (0, %u]. Will use default value: %u.\n",
+                      lu_cache_percent, LU_CACHE_PERCENT_MAX,
+                      LU_CACHE_PERCENT_DEFAULT);
+
+                lu_cache_percent = LU_CACHE_PERCENT_DEFAULT;
+        }
+        cache_size = cache_size / 100 * lu_cache_percent *
                 (CFS_PAGE_SIZE / 1024);
 
         for (bits = 1; (1 << bits) < cache_size; ++bits) {
@@ -723,45 +850,171 @@ static int lu_htable_order(void)
         return bits;
 }
 
-static cfs_lock_class_key_t lu_site_guard_class;
+static unsigned lu_obj_hop_hash(cfs_hash_t *hs,
+                                const void *key, unsigned mask)
+{
+        struct lu_fid  *fid = (struct lu_fid *)key;
+        __u32           hash;
+
+        hash = fid_flatten32(fid);
+        hash += (hash >> 4) + (hash << 12); /* mixing oid and seq */
+        hash = cfs_hash_long(hash, hs->hs_bkt_bits);
+
+        /* give me another random factor */
+        hash -= cfs_hash_long((unsigned long)hs, fid_oid(fid) % 11 + 3);
+
+        hash <<= hs->hs_cur_bits - hs->hs_bkt_bits;
+        hash |= (fid_seq(fid) + fid_oid(fid)) & (CFS_HASH_NBKT(hs) - 1);
+
+        return hash & mask;
+}
+
+static void *lu_obj_hop_object(cfs_hlist_node_t *hnode)
+{
+        return cfs_hlist_entry(hnode, struct lu_object_header, loh_hash);
+}
+
+static void *lu_obj_hop_key(cfs_hlist_node_t *hnode)
+{
+        struct lu_object_header *h;
+
+        h = cfs_hlist_entry(hnode, struct lu_object_header, loh_hash);
+        return &h->loh_fid;
+}
+
+static int lu_obj_hop_keycmp(const void *key, cfs_hlist_node_t *hnode)
+{
+        struct lu_object_header *h;
+
+        h = cfs_hlist_entry(hnode, struct lu_object_header, loh_hash);
+        return lu_fid_eq(&h->loh_fid, (struct lu_fid *)key);
+}
+
+static void lu_obj_hop_get(cfs_hash_t *hs, cfs_hlist_node_t *hnode)
+{
+        struct lu_object_header *h;
+
+        h = cfs_hlist_entry(hnode, struct lu_object_header, loh_hash);
+        if (cfs_atomic_add_return(1, &h->loh_ref) == 1) {
+                struct lu_site_bkt_data *bkt;
+                cfs_hash_bd_t            bd;
+
+                cfs_hash_bd_get(hs, &h->loh_fid, &bd);
+                bkt = cfs_hash_bd_extra_get(hs, &bd);
+                bkt->lsb_busy++;
+        }
+}
+
+static void lu_obj_hop_put_locked(cfs_hash_t *hs, cfs_hlist_node_t *hnode)
+{
+        LBUG(); /* we should never called it */
+}
+
+cfs_hash_ops_t lu_site_hash_ops = {
+        .hs_hash        = lu_obj_hop_hash,
+        .hs_key         = lu_obj_hop_key,
+        .hs_keycmp      = lu_obj_hop_keycmp,
+        .hs_object      = lu_obj_hop_object,
+        .hs_get         = lu_obj_hop_get,
+        .hs_put_locked  = lu_obj_hop_put_locked,
+};
+
+void lu_dev_add_linkage(struct lu_site *s, struct lu_device *d)
+{
+       cfs_spin_lock(&s->ls_ld_lock);
+       if (cfs_list_empty(&d->ld_linkage))
+               cfs_list_add(&d->ld_linkage, &s->ls_ld_linkage);
+       cfs_spin_unlock(&s->ls_ld_lock);
+}
+EXPORT_SYMBOL(lu_dev_add_linkage);
+
+void lu_dev_del_linkage(struct lu_site *s, struct lu_device *d)
+{
+       cfs_spin_lock(&s->ls_ld_lock);
+       cfs_list_del_init(&d->ld_linkage);
+       cfs_spin_unlock(&s->ls_ld_lock);
+}
+EXPORT_SYMBOL(lu_dev_del_linkage);
 
 /**
  * Initialize site \a s, with \a d as the top level device.
  */
+#define LU_SITE_BITS_MIN    12
+#define LU_SITE_BITS_MAX    24
+/**
+ * total 256 buckets, we don't want too many buckets because:
+ * - consume too much memory
+ * - avoid unbalanced LRU list
+ */
+#define LU_SITE_BKT_BITS    8
+
 int lu_site_init(struct lu_site *s, struct lu_device *top)
 {
+        struct lu_site_bkt_data *bkt;
+        cfs_hash_bd_t bd;
+        char name[16];
         int bits;
-        int size;
         int i;
         ENTRY;
 
         memset(s, 0, sizeof *s);
-        cfs_rwlock_init(&s->ls_guard);
-        cfs_lockdep_set_class(&s->ls_guard, &lu_site_guard_class);
-        CFS_INIT_LIST_HEAD(&s->ls_lru);
+        bits = lu_htable_order();
+        snprintf(name, 16, "lu_site_%s", top->ld_type->ldt_name);
+        for (bits = min(max(LU_SITE_BITS_MIN, bits), LU_SITE_BITS_MAX);
+             bits >= LU_SITE_BITS_MIN; bits--) {
+                s->ls_obj_hash = cfs_hash_create(name, bits, bits,
+                                                 bits - LU_SITE_BKT_BITS,
+                                                 sizeof(*bkt), 0, 0,
+                                                 &lu_site_hash_ops,
+                                                 CFS_HASH_SPIN_BKTLOCK |
+                                                 CFS_HASH_NO_ITEMREF |
+                                                 CFS_HASH_DEPTH |
+                                                 CFS_HASH_ASSERT_EMPTY);
+                if (s->ls_obj_hash != NULL)
+                        break;
+        }
+
+        if (s->ls_obj_hash == NULL) {
+                CERROR("failed to create lu_site hash with bits: %d\n", bits);
+                return -ENOMEM;
+        }
+
+        cfs_hash_for_each_bucket(s->ls_obj_hash, &bd, i) {
+                bkt = cfs_hash_bd_extra_get(s->ls_obj_hash, &bd);
+                CFS_INIT_LIST_HEAD(&bkt->lsb_lru);
+                cfs_waitq_init(&bkt->lsb_marche_funebre);
+        }
+
+        s->ls_stats = lprocfs_alloc_stats(LU_SS_LAST_STAT, 0);
+        if (s->ls_stats == NULL) {
+                cfs_hash_putref(s->ls_obj_hash);
+                s->ls_obj_hash = NULL;
+                return -ENOMEM;
+        }
+
+        lprocfs_counter_init(s->ls_stats, LU_SS_CREATED,
+                             0, "created", "created");
+        lprocfs_counter_init(s->ls_stats, LU_SS_CACHE_HIT,
+                             0, "cache_hit", "cache_hit");
+        lprocfs_counter_init(s->ls_stats, LU_SS_CACHE_MISS,
+                             0, "cache_miss", "cache_miss");
+        lprocfs_counter_init(s->ls_stats, LU_SS_CACHE_RACE,
+                             0, "cache_race", "cache_race");
+        lprocfs_counter_init(s->ls_stats, LU_SS_CACHE_DEATH_RACE,
+                             0, "cache_death_race", "cache_death_race");
+        lprocfs_counter_init(s->ls_stats, LU_SS_LRU_PURGED,
+                             0, "lru_purged", "lru_purged");
+
         CFS_INIT_LIST_HEAD(&s->ls_linkage);
-        cfs_waitq_init(&s->ls_marche_funebre);
         s->ls_top_dev = top;
         top->ld_site = s;
         lu_device_get(top);
         lu_ref_add(&top->ld_reference, "site-top", s);
 
-        for (bits = lu_htable_order(), size = 1 << bits;
-             (s->ls_hash =
-              cfs_alloc_large(size * sizeof s->ls_hash[0])) == NULL;
-             --bits, size >>= 1) {
-                /*
-                 * Scale hash table down, until allocation succeeds.
-                 */
-                ;
-        }
-
-        s->ls_hash_size = size;
-        s->ls_hash_bits = bits;
-        s->ls_hash_mask = size - 1;
+        CFS_INIT_LIST_HEAD(&s->ls_ld_linkage);
+        cfs_spin_lock_init(&s->ls_ld_lock);
 
-        for (i = 0; i < size; i++)
-                CFS_INIT_HLIST_HEAD(&s->ls_hash[i]);
+       lu_dev_add_linkage(s, top);
 
         RETURN(0);
 }
@@ -772,26 +1025,24 @@ EXPORT_SYMBOL(lu_site_init);
  */
 void lu_site_fini(struct lu_site *s)
 {
-        LASSERT(cfs_list_empty(&s->ls_lru));
-        LASSERT(s->ls_total == 0);
-
-        cfs_down(&lu_sites_guard);
+        cfs_mutex_lock(&lu_sites_guard);
         cfs_list_del_init(&s->ls_linkage);
-        cfs_up(&lu_sites_guard);
-
-        if (s->ls_hash != NULL) {
-                int i;
-                for (i = 0; i < s->ls_hash_size; i++)
-                        LASSERT(cfs_hlist_empty(&s->ls_hash[i]));
-                cfs_free_large(s->ls_hash);
-                s->ls_hash = NULL;
+        cfs_mutex_unlock(&lu_sites_guard);
+
+        if (s->ls_obj_hash != NULL) {
+                cfs_hash_putref(s->ls_obj_hash);
+                s->ls_obj_hash = NULL;
         }
+
         if (s->ls_top_dev != NULL) {
                 s->ls_top_dev->ld_site = NULL;
                 lu_ref_del(&s->ls_top_dev->ld_reference, "site-top", s);
                 lu_device_put(s->ls_top_dev);
                 s->ls_top_dev = NULL;
         }
+
+        if (s->ls_stats != NULL)
+                lprocfs_free_stats(&s->ls_stats);
 }
 EXPORT_SYMBOL(lu_site_fini);
 
@@ -801,11 +1052,11 @@ EXPORT_SYMBOL(lu_site_fini);
 int lu_site_init_finish(struct lu_site *s)
 {
         int result;
-        cfs_down(&lu_sites_guard);
+        cfs_mutex_lock(&lu_sites_guard);
         result = lu_context_refill(&lu_shrink_env.le_ctx);
         if (result == 0)
                 cfs_list_add(&s->ls_linkage, &lu_sites);
-        cfs_up(&lu_sites_guard);
+        cfs_mutex_unlock(&lu_sites_guard);
         return result;
 }
 EXPORT_SYMBOL(lu_site_init_finish);
@@ -840,6 +1091,7 @@ int lu_device_init(struct lu_device *d, struct lu_device_type *t)
         cfs_atomic_set(&d->ld_ref, 0);
         d->ld_type = t;
         lu_ref_init(&d->ld_reference);
+        CFS_INIT_LIST_HEAD(&d->ld_linkage);
         return 0;
 }
 EXPORT_SYMBOL(lu_device_init);
@@ -994,15 +1246,6 @@ void lu_stack_fini(const struct lu_env *env, struct lu_device *top)
         /* purge again. */
         lu_site_purge(env, site, ~0);
 
-        if (!cfs_list_empty(&site->ls_lru) || site->ls_total != 0) {
-                /*
-                 * Uh-oh, objects still exist.
-                 */
-                static DECLARE_LU_CDEBUG_PRINT_INFO(cookie, D_ERROR);
-
-                lu_site_print(env, site, &cookie, lu_cdebug_printer);
-        }
-
         for (scan = top; scan != NULL; scan = next) {
                 const struct lu_device_type *ldt = scan->ld_type;
                 struct obd_type             *type;
@@ -1021,12 +1264,12 @@ enum {
         /**
          * Maximal number of tld slots.
          */
-        LU_CONTEXT_KEY_NR = 32
+        LU_CONTEXT_KEY_NR = 40
 };
 
 static struct lu_context_key *lu_keys[LU_CONTEXT_KEY_NR] = { NULL, };
 
-static cfs_spinlock_t lu_keys_guard = CFS_SPIN_LOCK_UNLOCKED;
+static DEFINE_SPINLOCK(lu_keys_guard);
 
 /**
  * Global counter incremented whenever key is registered, unregistered,
@@ -1080,13 +1323,14 @@ static void key_fini(struct lu_context *ctx, int index)
                 key->lct_fini(ctx, key, ctx->lc_value[index]);
                 lu_ref_del(&key->lct_reference, "ctx", ctx);
                 cfs_atomic_dec(&key->lct_used);
-                LASSERT(key->lct_owner != NULL);
-                if (!(ctx->lc_tags & LCT_NOREF)) {
-                        LASSERT(cfs_module_refcount(key->lct_owner) > 0);
-                        cfs_module_put(key->lct_owner);
-                }
-                ctx->lc_value[index] = NULL;
-        }
+
+               LASSERT(key->lct_owner != NULL);
+               if ((ctx->lc_tags & LCT_NOREF) == 0) {
+                       LINVRNT(cfs_module_refcount(key->lct_owner) > 0);
+                       cfs_module_put(key->lct_owner);
+               }
+               ctx->lc_value[index] = NULL;
+       }
 }
 
 /**
@@ -1251,23 +1495,23 @@ EXPORT_SYMBOL(lu_context_key_revive);
 
 static void keys_fini(struct lu_context *ctx)
 {
-        int i;
+       int     i;
 
-        cfs_spin_lock(&lu_keys_guard);
-        if (ctx->lc_value != NULL) {
-                for (i = 0; i < ARRAY_SIZE(lu_keys); ++i)
-                        key_fini(ctx, i);
-                OBD_FREE(ctx->lc_value,
-                         ARRAY_SIZE(lu_keys) * sizeof ctx->lc_value[0]);
-                ctx->lc_value = NULL;
-        }
-        cfs_spin_unlock(&lu_keys_guard);
+       if (ctx->lc_value == NULL)
+               return;
+
+       for (i = 0; i < ARRAY_SIZE(lu_keys); ++i)
+               key_fini(ctx, i);
+
+       OBD_FREE(ctx->lc_value, ARRAY_SIZE(lu_keys) * sizeof ctx->lc_value[0]);
+       ctx->lc_value = NULL;
 }
 
 static int keys_fill(struct lu_context *ctx)
 {
         int i;
 
+        LINVRNT(ctx->lc_value != NULL);
         for (i = 0; i < ARRAY_SIZE(lu_keys); ++i) {
                 struct lu_context_key *key;
 
@@ -1309,17 +1553,11 @@ static int keys_fill(struct lu_context *ctx)
 
 static int keys_init(struct lu_context *ctx)
 {
-        int result;
-
-        OBD_ALLOC(ctx->lc_value, ARRAY_SIZE(lu_keys) * sizeof ctx->lc_value[0]);
-        if (likely(ctx->lc_value != NULL))
-                result = keys_fill(ctx);
-        else
-                result = -ENOMEM;
+       OBD_ALLOC(ctx->lc_value, ARRAY_SIZE(lu_keys) * sizeof ctx->lc_value[0]);
+       if (likely(ctx->lc_value != NULL))
+               return keys_fill(ctx);
 
-        if (result != 0)
-                keys_fini(ctx);
-        return result;
+       return -ENOMEM;
 }
 
 /**
@@ -1327,6 +1565,8 @@ static int keys_init(struct lu_context *ctx)
  */
 int lu_context_init(struct lu_context *ctx, __u32 tags)
 {
+       int     rc;
+
         memset(ctx, 0, sizeof *ctx);
         ctx->lc_state = LCS_INITIALIZED;
         ctx->lc_tags = tags;
@@ -1334,9 +1574,15 @@ int lu_context_init(struct lu_context *ctx, __u32 tags)
                 cfs_spin_lock(&lu_keys_guard);
                 cfs_list_add(&ctx->lc_remember, &lu_context_remembered);
                 cfs_spin_unlock(&lu_keys_guard);
-        } else
-                CFS_INIT_LIST_HEAD(&ctx->lc_remember);
-        return keys_init(ctx);
+       } else {
+               CFS_INIT_LIST_HEAD(&ctx->lc_remember);
+       }
+
+       rc = keys_init(ctx);
+       if (rc != 0)
+               lu_context_fini(ctx);
+
+       return rc;
 }
 EXPORT_SYMBOL(lu_context_init);
 
@@ -1345,12 +1591,19 @@ EXPORT_SYMBOL(lu_context_init);
  */
 void lu_context_fini(struct lu_context *ctx)
 {
-        LINVRNT(ctx->lc_state == LCS_INITIALIZED || ctx->lc_state == LCS_LEFT);
-        ctx->lc_state = LCS_FINALIZED;
-        keys_fini(ctx);
-        cfs_spin_lock(&lu_keys_guard);
-        cfs_list_del_init(&ctx->lc_remember);
-        cfs_spin_unlock(&lu_keys_guard);
+       LINVRNT(ctx->lc_state == LCS_INITIALIZED || ctx->lc_state == LCS_LEFT);
+       ctx->lc_state = LCS_FINALIZED;
+
+       if ((ctx->lc_tags & LCT_REMEMBER) == 0) {
+               LASSERT(cfs_list_empty(&ctx->lc_remember));
+               keys_fini(ctx);
+
+       } else { /* could race with key degister */
+               cfs_spin_lock(&lu_keys_guard);
+               keys_fini(ctx);
+               cfs_list_del_init(&ctx->lc_remember);
+               cfs_spin_unlock(&lu_keys_guard);
+       }
 }
 EXPORT_SYMBOL(lu_context_fini);
 
@@ -1391,15 +1644,61 @@ EXPORT_SYMBOL(lu_context_exit);
 
 /**
  * Allocate for context all missing keys that were registered after context
- * creation.
+ * creation. key_set_version is only changed in rare cases when modules
+ * are loaded and removed.
  */
 int lu_context_refill(struct lu_context *ctx)
 {
-        LINVRNT(ctx->lc_value != NULL);
-        return ctx->lc_version == key_set_version ? 0 : keys_fill(ctx);
+        return likely(ctx->lc_version == key_set_version) ? 0 : keys_fill(ctx);
 }
 EXPORT_SYMBOL(lu_context_refill);
 
+/**
+ * lu_ctx_tags/lu_ses_tags will be updated if there are new types of
+ * obd being added. Currently, this is only used on client side, specifically
+ * for echo device client, for other stack (like ptlrpc threads), context are
+ * predefined when the lu_device type are registered, during the module probe
+ * phase.
+ */
+__u32 lu_context_tags_default = 0;
+__u32 lu_session_tags_default = 0;
+
+void lu_context_tags_update(__u32 tags)
+{
+        cfs_spin_lock(&lu_keys_guard);
+        lu_context_tags_default |= tags;
+        key_set_version ++;
+        cfs_spin_unlock(&lu_keys_guard);
+}
+EXPORT_SYMBOL(lu_context_tags_update);
+
+void lu_context_tags_clear(__u32 tags)
+{
+        cfs_spin_lock(&lu_keys_guard);
+        lu_context_tags_default &= ~tags;
+        key_set_version ++;
+        cfs_spin_unlock(&lu_keys_guard);
+}
+EXPORT_SYMBOL(lu_context_tags_clear);
+
+void lu_session_tags_update(__u32 tags)
+{
+        cfs_spin_lock(&lu_keys_guard);
+        lu_session_tags_default |= tags;
+        key_set_version ++;
+        cfs_spin_unlock(&lu_keys_guard);
+}
+EXPORT_SYMBOL(lu_session_tags_update);
+
+void lu_session_tags_clear(__u32 tags)
+{
+        cfs_spin_lock(&lu_keys_guard);
+        lu_session_tags_default &= ~tags;
+        key_set_version ++;
+        cfs_spin_unlock(&lu_keys_guard);
+}
+EXPORT_SYMBOL(lu_session_tags_clear);
+
 int lu_env_init(struct lu_env *env, __u32 tags)
 {
         int result;
@@ -1431,26 +1730,123 @@ int lu_env_refill(struct lu_env *env)
 }
 EXPORT_SYMBOL(lu_env_refill);
 
+/**
+ * Currently, this API will only be used by echo client.
+ * Because echo client and normal lustre client will share
+ * same cl_env cache. So echo client needs to refresh
+ * the env context after it get one from the cache, especially
+ * when normal client and echo client co-exist in the same client.
+ */
+int lu_env_refill_by_tags(struct lu_env *env, __u32 ctags,
+                          __u32 stags)
+{
+        int    result;
+
+        if ((env->le_ctx.lc_tags & ctags) != ctags) {
+                env->le_ctx.lc_version = 0;
+                env->le_ctx.lc_tags |= ctags;
+        }
+
+        if (env->le_ses && (env->le_ses->lc_tags & stags) != stags) {
+                env->le_ses->lc_version = 0;
+                env->le_ses->lc_tags |= stags;
+        }
+
+        result = lu_env_refill(env);
+
+        return result;
+}
+EXPORT_SYMBOL(lu_env_refill_by_tags);
+
 static struct cfs_shrinker *lu_site_shrinker = NULL;
 
+typedef struct lu_site_stats{
+        unsigned        lss_populated;
+        unsigned        lss_max_search;
+        unsigned        lss_total;
+        unsigned        lss_busy;
+} lu_site_stats_t;
+
+static void lu_site_stats_get(cfs_hash_t *hs,
+                              lu_site_stats_t *stats, int populated)
+{
+        cfs_hash_bd_t bd;
+        int           i;
+
+        cfs_hash_for_each_bucket(hs, &bd, i) {
+                struct lu_site_bkt_data *bkt = cfs_hash_bd_extra_get(hs, &bd);
+                cfs_hlist_head_t        *hhead;
+
+                cfs_hash_bd_lock(hs, &bd, 1);
+                stats->lss_busy  += bkt->lsb_busy;
+                stats->lss_total += cfs_hash_bd_count_get(&bd);
+                stats->lss_max_search = max((int)stats->lss_max_search,
+                                            cfs_hash_bd_depmax_get(&bd));
+                if (!populated) {
+                        cfs_hash_bd_unlock(hs, &bd, 1);
+                        continue;
+                }
+
+                cfs_hash_bd_for_each_hlist(hs, &bd, hhead) {
+                        if (!cfs_hlist_empty(hhead))
+                                stats->lss_populated++;
+                }
+                cfs_hash_bd_unlock(hs, &bd, 1);
+        }
+}
+
 #ifdef __KERNEL__
-static int lu_cache_shrink(int nr, unsigned int gfp_mask)
+
+/*
+ * There exists a potential lock inversion deadlock scenario when using
+ * Lustre on top of ZFS. This occurs between one of ZFS's
+ * buf_hash_table.ht_lock's, and Lustre's lu_sites_guard lock. Essentially,
+ * thread A will take the lu_sites_guard lock and sleep on the ht_lock,
+ * while thread B will take the ht_lock and sleep on the lu_sites_guard
+ * lock. Obviously neither thread will wake and drop their respective hold
+ * on their lock.
+ *
+ * To prevent this from happening we must ensure the lu_sites_guard lock is
+ * not taken while down this code path. ZFS reliably does not set the
+ * __GFP_FS bit in its code paths, so this can be used to determine if it
+ * is safe to take the lu_sites_guard lock.
+ *
+ * Ideally we should accurately return the remaining number of cached
+ * objects without taking the  lu_sites_guard lock, but this is not
+ * possible in the current implementation.
+ */
+static int lu_cache_shrink(SHRINKER_ARGS(sc, nr_to_scan, gfp_mask))
 {
+        lu_site_stats_t stats;
         struct lu_site *s;
         struct lu_site *tmp;
         int cached = 0;
-        int remain = nr;
+        int remain = shrink_param(sc, nr_to_scan);
         CFS_LIST_HEAD(splice);
 
-        if (nr != 0) {
-                if (!(gfp_mask & __GFP_FS))
+       if (!(shrink_param(sc, gfp_mask) & __GFP_FS)) {
+               if (remain != 0)
                         return -1;
-                CDEBUG(D_INODE, "Shrink %d objects\n", nr);
+               else
+                       /* We must not take the lu_sites_guard lock when
+                        * __GFP_FS is *not* set because of the deadlock
+                        * possibility detailed above. Additionally,
+                        * since we cannot determine the number of
+                        * objects in the cache without taking this
+                        * lock, we're in a particularly tough spot. As
+                        * a result, we'll just lie and say our cache is
+                        * empty. This _should_ be ok, as we can't
+                        * reclaim objects when __GFP_FS is *not* set
+                        * anyways.
+                        */
+                       return 0;
         }
 
-        cfs_down(&lu_sites_guard);
+       CDEBUG(D_INODE, "Shrink %d objects\n", remain);
+
+        cfs_mutex_lock(&lu_sites_guard);
         cfs_list_for_each_entry_safe(s, tmp, &lu_sites, ls_linkage) {
-                if (nr != 0) {
+                if (shrink_param(sc, nr_to_scan) != 0) {
                         remain = lu_site_purge(&lu_shrink_env, s, remain);
                         /*
                          * Move just shrunk site to the tail of site list to
@@ -1458,17 +1854,18 @@ static int lu_cache_shrink(int nr, unsigned int gfp_mask)
                          */
                         cfs_list_move_tail(&s->ls_linkage, &splice);
                 }
-                cfs_read_lock(&s->ls_guard);
-                cached += s->ls_total - s->ls_busy;
-                cfs_read_unlock(&s->ls_guard);
-                if (nr && remain <= 0)
+
+                memset(&stats, 0, sizeof(stats));
+                lu_site_stats_get(s->ls_obj_hash, &stats, 0);
+                cached += stats.lss_total - stats.lss_busy;
+                if (shrink_param(sc, nr_to_scan) && remain <= 0)
                         break;
         }
         cfs_list_splice(&splice, lu_sites.prev);
-        cfs_up(&lu_sites_guard);
+        cfs_mutex_unlock(&lu_sites_guard);
 
         cached = (cached / 100) * sysctl_vfs_cache_pressure;
-        if (nr == 0)
+        if (shrink_param(sc, nr_to_scan) == 0)
                 CDEBUG(D_INODE, "%d objects cached\n", cached);
         return cached;
 }
@@ -1546,7 +1943,7 @@ int lu_global_init(void)
 {
         int result;
 
-        CDEBUG(D_CONSOLE, "Lustre LU module (%p).\n", &lu_keys);
+        CDEBUG(D_INFO, "Lustre LU module (%p).\n", &lu_keys);
 
         result = lu_ref_global_init();
         if (result != 0)
@@ -1561,9 +1958,9 @@ int lu_global_init(void)
          * conservatively. This should not be too bad, because this
          * environment is global.
          */
-        cfs_down(&lu_sites_guard);
+        cfs_mutex_lock(&lu_sites_guard);
         result = lu_env_init(&lu_shrink_env, LCT_SHRINKER);
-        cfs_up(&lu_sites_guard);
+        cfs_mutex_unlock(&lu_sites_guard);
         if (result != 0)
                 return result;
 
@@ -1617,9 +2014,9 @@ void lu_global_fini(void)
          * Tear shrinker environment down _after_ de-registering
          * lu_global_key, because the latter has a value in the former.
          */
-        cfs_down(&lu_sites_guard);
+        cfs_mutex_lock(&lu_sites_guard);
         lu_env_fini(&lu_shrink_env);
-        cfs_up(&lu_sites_guard);
+        cfs_mutex_unlock(&lu_sites_guard);
 
         lu_ref_global_fini();
 }
@@ -1630,34 +2027,41 @@ struct lu_buf LU_BUF_NULL = {
 };
 EXPORT_SYMBOL(LU_BUF_NULL);
 
+static __u32 ls_stats_read(struct lprocfs_stats *stats, int idx)
+{
+#ifdef LPROCFS
+        struct lprocfs_counter ret;
+
+        lprocfs_stats_collect(stats, idx, &ret);
+        return (__u32)ret.lc_count;
+#else
+        return 0;
+#endif
+}
+
 /**
  * Output site statistical counters into a buffer. Suitable for
  * lprocfs_rd_*()-style functions.
  */
 int lu_site_stats_print(const struct lu_site *s, char *page, int count)
 {
-        int i;
-        int populated;
+        lu_site_stats_t stats;
 
-        /*
-         * How many hash buckets are not-empty? Don't bother with locks: it's
-         * an estimation anyway.
-         */
-        for (i = 0, populated = 0; i < s->ls_hash_size; i++)
-                populated += !cfs_hlist_empty(&s->ls_hash[i]);
-
-        return snprintf(page, count, "%d %d %d/%d %d %d %d %d %d %d %d\n",
-                        s->ls_total,
-                        s->ls_busy,
-                        populated,
-                        s->ls_hash_size,
-                        s->ls_stats.s_created,
-                        s->ls_stats.s_cache_hit,
-                        s->ls_stats.s_cache_miss,
-                        s->ls_stats.s_cache_check,
-                        s->ls_stats.s_cache_race,
-                        s->ls_stats.s_cache_death_race,
-                        s->ls_stats.s_lru_purged);
+        memset(&stats, 0, sizeof(stats));
+        lu_site_stats_get(s->ls_obj_hash, &stats, 1);
+
+        return snprintf(page, count, "%d/%d %d/%d %d %d %d %d %d %d %d\n",
+                        stats.lss_busy,
+                        stats.lss_total,
+                        stats.lss_populated,
+                        CFS_HASH_NHLIST(s->ls_obj_hash),
+                        stats.lss_max_search,
+                        ls_stats_read(s->ls_stats, LU_SS_CREATED),
+                        ls_stats_read(s->ls_stats, LU_SS_CACHE_HIT),
+                        ls_stats_read(s->ls_stats, LU_SS_CACHE_MISS),
+                        ls_stats_read(s->ls_stats, LU_SS_CACHE_RACE),
+                        ls_stats_read(s->ls_stats, LU_SS_CACHE_DEATH_RACE),
+                        ls_stats_read(s->ls_stats, LU_SS_LRU_PURGED));
 }
 EXPORT_SYMBOL(lu_site_stats_print);
 
@@ -1674,13 +2078,16 @@ EXPORT_SYMBOL(lu_time_names);
 int lu_kmem_init(struct lu_kmem_descr *caches)
 {
         int result;
+        struct lu_kmem_descr *iter = caches;
 
-        for (result = 0; caches->ckd_cache != NULL; ++caches) {
-                *caches->ckd_cache = cfs_mem_cache_create(caches->ckd_name,
-                                                          caches->ckd_size,
-                                                          0, 0);
-                if (*caches->ckd_cache == NULL) {
+        for (result = 0; iter->ckd_cache != NULL; ++iter) {
+                *iter->ckd_cache = cfs_mem_cache_create(iter->ckd_name,
+                                                        iter->ckd_size,
+                                                        0, 0);
+                if (*iter->ckd_cache == NULL) {
                         result = -ENOMEM;
+                        /* free all previously allocated caches */
+                        lu_kmem_fini(caches);
                         break;
                 }
         }
@@ -1706,3 +2113,53 @@ void lu_kmem_fini(struct lu_kmem_descr *caches)
         }
 }
 EXPORT_SYMBOL(lu_kmem_fini);
+
+/**
+ * Temporary solution to be able to assign fid in ->do_create()
+ * till we have fully-functional OST fids
+ */
+void lu_object_assign_fid(const struct lu_env *env, struct lu_object *o,
+                         const struct lu_fid *fid)
+{
+       struct lu_site          *s = o->lo_dev->ld_site;
+       struct lu_fid           *old = &o->lo_header->loh_fid;
+       struct lu_site_bkt_data *bkt;
+       struct lu_object        *shadow;
+       cfs_waitlink_t           waiter;
+       cfs_hash_t              *hs;
+       cfs_hash_bd_t            bd;
+       __u64                    version = 0;
+
+       LASSERT(fid_is_zero(old));
+
+       hs = s->ls_obj_hash;
+       cfs_hash_bd_get_and_lock(hs, (void *)fid, &bd, 1);
+       shadow = htable_lookup(s, &bd, fid, &waiter, &version);
+       /* supposed to be unique */
+       LASSERT(shadow == NULL);
+       *old = *fid;
+       bkt = cfs_hash_bd_extra_get(hs, &bd);
+       cfs_hash_bd_add_locked(hs, &bd, &o->lo_header->loh_hash);
+       bkt->lsb_busy++;
+       cfs_hash_bd_unlock(hs, &bd, 1);
+}
+EXPORT_SYMBOL(lu_object_assign_fid);
+
+/**
+ * allocates object with 0 (non-assiged) fid
+ * XXX: temporary solution to be able to assign fid in ->do_create()
+ *      till we have fully-functional OST fids
+ */
+struct lu_object *lu_object_anon(const struct lu_env *env,
+                                struct lu_device *dev,
+                                const struct lu_object_conf *conf)
+{
+       struct lu_fid     fid;
+       struct lu_object *o;
+
+       fid_zero(&fid);
+       o = lu_object_alloc(env, dev, &fid, conf);
+
+       return o;
+}
+EXPORT_SYMBOL(lu_object_anon);