Whamcloud - gitweb
LU-2282 obdclass: Slightly increase the size of lu_keys[]
[fs/lustre-release.git] / lustre / obdclass / lu_object.c
index f0e9535..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.
@@ -28,9 +26,8 @@
 /*
  * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  * Use is subject to license terms.
- */
-/*
- * Copyright (c) 2011 Whamcloud, Inc.
+ *
+ * Copyright (c) 2011, 2012, Whamcloud, Inc.
  */
 /*
  * This file is part of Lustre, http://www.lustre.org/
@@ -46,9 +43,6 @@
  */
 
 #define DEBUG_SUBSYSTEM S_CLASS
-#ifndef EXPORT_SYMTAB
-# define EXPORT_SYMTAB
-#endif
 
 #include <libcfs/libcfs.h>
 
@@ -81,11 +75,32 @@ void lu_object_put(const struct lu_env *env, struct lu_object *o)
         struct lu_site          *site;
         struct lu_object        *orig;
         cfs_hash_bd_t            bd;
+       const struct lu_fid     *fid;
 
         top  = o->lo_header;
         site = o->lo_dev->ld_site;
         orig = o;
 
+       /*
+        * 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);
 
@@ -113,6 +128,8 @@ void lu_object_put(const struct lu_env *env, struct lu_object *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;
         }
@@ -129,7 +146,6 @@ void lu_object_put(const struct lu_env *env, struct lu_object *o)
          * and we can safely destroy object below.
          */
         cfs_hash_bd_del_locked(site->ls_obj_hash, &bd, &top->loh_hash);
-        cfs_list_del_init(&top->loh_lru);
         cfs_hash_bd_unlock(site->ls_obj_hash, &bd, 1);
         /*
          * Object was already removed from hash and lru above, can
@@ -140,6 +156,18 @@ void lu_object_put(const struct lu_env *env, struct lu_object *o)
 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
@@ -285,20 +313,7 @@ int lu_site_purge(const struct lu_env *env, struct lu_site *s, int nr)
                 bkt = cfs_hash_bd_extra_get(s->ls_obj_hash, &bd);
 
                 cfs_list_for_each_entry_safe(h, temp, &bkt->lsb_lru, loh_lru) {
-                        /*
-                         * 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.
-                         */
-                        if (cfs_atomic_read(&h->loh_ref) > 0)
-                                continue;
+                        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);
@@ -367,7 +382,7 @@ enum {
          *
          * XXX overflow is not handled correctly.
          */
-        LU_CDEBUG_LINE = 256
+        LU_CDEBUG_LINE = 512
 };
 
 struct lu_cdebug_data {
@@ -385,7 +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
 };
@@ -396,8 +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;
@@ -415,10 +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);
@@ -516,6 +530,7 @@ static struct lu_object *htable_lookup(struct lu_site *s,
         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);
         }
 
@@ -564,7 +579,6 @@ static struct lu_object *lu_object_new(const struct lu_env *env,
         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);
-        cfs_list_add_tail(&o->lo_header->loh_lru, &bkt->lsb_lru);
         bkt->lsb_busy++;
         cfs_hash_bd_unlock(hs, &bd, 1);
         return o;
@@ -635,7 +649,6 @@ static struct lu_object *lu_object_find_try(const struct lu_env *env,
 
                 bkt = cfs_hash_bd_extra_get(hs, &bd);
                 cfs_hash_bd_add_locked(hs, &bd, &o->lo_header->loh_hash);
-                cfs_list_add_tail(&o->lo_header->loh_lru, &bkt->lsb_lru);
                 bkt->lsb_busy++;
                 cfs_hash_bd_unlock(hs, &bd, 1);
                 return o;
@@ -737,7 +750,7 @@ 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.
@@ -841,10 +854,18 @@ static unsigned lu_obj_hop_hash(cfs_hash_t *hs,
                                 const void *key, unsigned mask)
 {
         struct lu_fid  *fid = (struct lu_fid *)key;
-        unsigned        hash;
+        __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);
 
-        hash = (fid_seq(fid) + fid_oid(fid)) & (CFS_HASH_NBKT(hs) - 1);
-        hash += fid_hash(fid, hs->hs_bkt_bits) << hs->hs_bkt_bits;
         return hash & mask;
 }
 
@@ -898,31 +919,50 @@ cfs_hash_ops_t lu_site_hash_ops = {
         .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    23
+#define LU_SITE_BITS_MAX    24
 /**
- * total 128 buckets, we don't want too many buckets because:
+ * total 256 buckets, we don't want too many buckets because:
  * - consume too much memory
  * - avoid unbalanced LRU list
  */
-#define LU_SITE_BKT_BITS    7
+#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 i;
         ENTRY;
 
         memset(s, 0, sizeof *s);
         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("lu_site", bits, bits,
+                s->ls_obj_hash = cfs_hash_create(name, bits, bits,
                                                  bits - LU_SITE_BKT_BITS,
                                                  sizeof(*bkt), 0, 0,
                                                  &lu_site_hash_ops,
@@ -971,6 +1011,11 @@ int lu_site_init(struct lu_site *s, struct lu_device *top)
         lu_device_get(top);
         lu_ref_add(&top->ld_reference, "site-top", s);
 
+        CFS_INIT_LIST_HEAD(&s->ls_ld_linkage);
+        cfs_spin_lock_init(&s->ls_ld_lock);
+
+       lu_dev_add_linkage(s, top);
+
         RETURN(0);
 }
 EXPORT_SYMBOL(lu_site_init);
@@ -980,9 +1025,9 @@ EXPORT_SYMBOL(lu_site_init);
  */
 void lu_site_fini(struct lu_site *s)
 {
-        cfs_down(&lu_sites_guard);
+        cfs_mutex_lock(&lu_sites_guard);
         cfs_list_del_init(&s->ls_linkage);
-        cfs_up(&lu_sites_guard);
+        cfs_mutex_unlock(&lu_sites_guard);
 
         if (s->ls_obj_hash != NULL) {
                 cfs_hash_putref(s->ls_obj_hash);
@@ -1007,11 +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);
@@ -1046,6 +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);
@@ -1200,15 +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_hash_is_empty(site->ls_obj_hash)) {
-                /*
-                 * 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;
@@ -1227,12 +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,
@@ -1286,13 +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;
+       }
 }
 
 /**
@@ -1457,23 +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;
 
@@ -1515,17 +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))
+               return keys_fill(ctx);
 
-        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;
-
-        if (result != 0)
-                keys_fini(ctx);
-        return result;
+       return -ENOMEM;
 }
 
 /**
@@ -1533,6 +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;
@@ -1540,9 +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);
 
@@ -1551,12 +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);
 
@@ -1597,15 +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;
@@ -1637,6 +1730,34 @@ 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{
@@ -1675,25 +1796,57 @@ static void lu_site_stats_get(cfs_hash_t *hs,
 }
 
 #ifdef __KERNEL__
-static int lu_cache_shrink(SHRINKER_FIRST_ARG int nr_to_scan,
-                           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_to_scan;
+        int remain = shrink_param(sc, nr_to_scan);
         CFS_LIST_HEAD(splice);
 
-        if (nr_to_scan != 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_to_scan);
+               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_to_scan != 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
@@ -1705,14 +1858,14 @@ static int lu_cache_shrink(SHRINKER_FIRST_ARG int nr_to_scan,
                 memset(&stats, 0, sizeof(stats));
                 lu_site_stats_get(s->ls_obj_hash, &stats, 0);
                 cached += stats.lss_total - stats.lss_busy;
-                if (nr_to_scan && remain <= 0)
+                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_to_scan == 0)
+        if (shrink_param(sc, nr_to_scan) == 0)
                 CDEBUG(D_INODE, "%d objects cached\n", cached);
         return cached;
 }
@@ -1805,9 +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;
 
@@ -1861,9 +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();
 }
@@ -1960,3 +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);