Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 updates from Ted Ts'o:
 "Major changes for 3.14 include support for the newly added ZERO_RANGE
  and COLLAPSE_RANGE fallocate operations, and scalability improvements
  in the jbd2 layer and in xattr handling when the extended attributes
  spill over into an external block.

  Other than that, the usual clean ups and minor bug fixes"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (42 commits)
  ext4: fix premature freeing of partial clusters split across leaf blocks
  ext4: remove unneeded test of ret variable
  ext4: fix comment typo
  ext4: make ext4_block_zero_page_range static
  ext4: atomically set inode->i_flags in ext4_set_inode_flags()
  ext4: optimize Hurd tests when reading/writing inodes
  ext4: kill i_version support for Hurd-castrated file systems
  ext4: each filesystem creates and uses its own mb_cache
  fs/mbcache.c: doucple the locking of local from global data
  fs/mbcache.c: change block and index hash chain to hlist_bl_node
  ext4: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate
  ext4: refactor ext4_fallocate code
  ext4: Update inode i_size after the preallocation
  ext4: fix partial cluster handling for bigalloc file systems
  ext4: delete path dealloc code in ext4_ext_handle_uninitialized_extents
  ext4: only call sync_filesystm() when remounting read-only
  fs: push sync_filesystem() down to the file system's remount_fs()
  jbd2: improve error messages for inconsistent journal heads
  jbd2: minimize region locked by j_list_lock in jbd2_journal_forget()
  jbd2: minimize region locked by j_list_lock in journal_get_create_access()
  ...

1 files changed, 386 insertions, 154 deletions

diff --git a/fs/mbcache.c b/fs/mbcache.c
index e519e45..bf166e3 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -26,6 +26,41 @@
  * back on the lru list.
  */
 
+/*
+ * Lock descriptions and usage:
+ *
+ * Each hash chain of both the block and index hash tables now contains
+ * a built-in lock used to serialize accesses to the hash chain.
+ *
+ * Accesses to global data structures mb_cache_list and mb_cache_lru_list
+ * are serialized via the global spinlock mb_cache_spinlock.
+ *
+ * Each mb_cache_entry contains a spinlock, e_entry_lock, to serialize
+ * accesses to its local data, such as e_used and e_queued.
+ *
+ * Lock ordering:
+ *
+ * Each block hash chain's lock has the highest lock order, followed by an
+ * index hash chain's lock, mb_cache_bg_lock (used to implement mb_cache_entry's
+ * lock), and mb_cach_spinlock, with the lowest order.  While holding
+ * either a block or index hash chain lock, a thread can acquire an
+ * mc_cache_bg_lock, which in turn can also acquire mb_cache_spinlock.
+ *
+ * Synchronization:
+ *
+ * Since both mb_cache_entry_get and mb_cache_entry_find scan the block and
+ * index hash chian, it needs to lock the corresponding hash chain.  For each
+ * mb_cache_entry within the chain, it needs to lock the mb_cache_entry to
+ * prevent either any simultaneous release or free on the entry and also
+ * to serialize accesses to either the e_used or e_queued member of the entry.
+ *
+ * To avoid having a dangling reference to an already freed
+ * mb_cache_entry, an mb_cache_entry is only freed when it is not on a
+ * block hash chain and also no longer being referenced, both e_used,
+ * and e_queued are 0's.  When an mb_cache_entry is explicitly freed it is
+ * first removed from a block hash chain.
+ */
+
 #include <linux/kernel.h>
 #include <linux/module.h>
 
@@ -34,9 +69,10 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
-#include <linux/init.h>
+#include <linux/list_bl.h>
 #include <linux/mbcache.h>
-
+#include <linux/init.h>
+#include <linux/blockgroup_lock.h>
 
 #ifdef MB_CACHE_DEBUG
 # define mb_debug(f...) do { \
@@ -57,8 +93,14 @@
 
 #define MB_CACHE_WRITER ((unsigned short)~0U >> 1)
 
+#define MB_CACHE_ENTRY_LOCK_BITS	__builtin_log2(NR_BG_LOCKS)
+#define	MB_CACHE_ENTRY_LOCK_INDEX(ce)			\
+	(hash_long((unsigned long)ce, MB_CACHE_ENTRY_LOCK_BITS))
+
 static DECLARE_WAIT_QUEUE_HEAD(mb_cache_queue);
-		
+static struct blockgroup_lock *mb_cache_bg_lock;
+static struct kmem_cache *mb_cache_kmem_cache;
+
 MODULE_AUTHOR("Andreas Gruenbacher <a.gruenbacher@computer.org>");
 MODULE_DESCRIPTION("Meta block cache (for extended attributes)");
 MODULE_LICENSE("GPL");
@@ -86,58 +128,110 @@ static LIST_HEAD(mb_cache_list);
 static LIST_HEAD(mb_cache_lru_list);
 static DEFINE_SPINLOCK(mb_cache_spinlock);
 
+static inline void
+__spin_lock_mb_cache_entry(struct mb_cache_entry *ce)
+{
+	spin_lock(bgl_lock_ptr(mb_cache_bg_lock,
+		MB_CACHE_ENTRY_LOCK_INDEX(ce)));
+}
+
+static inline void
+__spin_unlock_mb_cache_entry(struct mb_cache_entry *ce)
+{
+	spin_unlock(bgl_lock_ptr(mb_cache_bg_lock,
+		MB_CACHE_ENTRY_LOCK_INDEX(ce)));
+}
+
 static inline int
-__mb_cache_entry_is_hashed(struct mb_cache_entry *ce)
+__mb_cache_entry_is_block_hashed(struct mb_cache_entry *ce)
 {
-	return !list_empty(&ce->e_block_list);
+	return !hlist_bl_unhashed(&ce->e_block_list);
 }
 
 
-static void
-__mb_cache_entry_unhash(struct mb_cache_entry *ce)
+static inline void
+__mb_cache_entry_unhash_block(struct mb_cache_entry *ce)
 {
-	if (__mb_cache_entry_is_hashed(ce)) {
-		list_del_init(&ce->e_block_list);
-		list_del(&ce->e_index.o_list);
-	}
+	if (__mb_cache_entry_is_block_hashed(ce))
+		hlist_bl_del_init(&ce->e_block_list);
 }
 
+static inline int
+__mb_cache_entry_is_index_hashed(struct mb_cache_entry *ce)
+{
+	return !hlist_bl_unhashed(&ce->e_index.o_list);
+}
+
+static inline void
+__mb_cache_entry_unhash_index(struct mb_cache_entry *ce)
+{
+	if (__mb_cache_entry_is_index_hashed(ce))
+		hlist_bl_del_init(&ce->e_index.o_list);
+}
+
+/*
+ * __mb_cache_entry_unhash_unlock()
+ *
+ * This function is called to unhash both the block and index hash
+ * chain.
+ * It assumes both the block and index hash chain is locked upon entry.
+ * It also unlock both hash chains both exit
+ */
+static inline void
+__mb_cache_entry_unhash_unlock(struct mb_cache_entry *ce)
+{
+	__mb_cache_entry_unhash_index(ce);
+	hlist_bl_unlock(ce->e_index_hash_p);
+	__mb_cache_entry_unhash_block(ce);
+	hlist_bl_unlock(ce->e_block_hash_p);
+}
 
 static void
 __mb_cache_entry_forget(struct mb_cache_entry *ce, gfp_t gfp_mask)
 {
 	struct mb_cache *cache = ce->e_cache;
 
-	mb_assert(!(ce->e_used || ce->e_queued));
+	mb_assert(!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt)));
 	kmem_cache_free(cache->c_entry_cache, ce);
 	atomic_dec(&cache->c_entry_count);
 }
 
-
 static void
-__mb_cache_entry_release_unlock(struct mb_cache_entry *ce)
-	__releases(mb_cache_spinlock)
+__mb_cache_entry_release(struct mb_cache_entry *ce)
 {
+	/* First lock the entry to serialize access to its local data. */
+	__spin_lock_mb_cache_entry(ce);
 	/* Wake up all processes queuing for this cache entry. */
 	if (ce->e_queued)
 		wake_up_all(&mb_cache_queue);
 	if (ce->e_used >= MB_CACHE_WRITER)
 		ce->e_used -= MB_CACHE_WRITER;
+	/*
+	 * Make sure that all cache entries on lru_list have
+	 * both e_used and e_qued of 0s.
+	 */
 	ce->e_used--;
-	if (!(ce->e_used || ce->e_queued)) {
-		if (!__mb_cache_entry_is_hashed(ce))
+	if (!(ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))) {
+		if (!__mb_cache_entry_is_block_hashed(ce)) {
+			__spin_unlock_mb_cache_entry(ce);
 			goto forget;
-		mb_assert(list_empty(&ce->e_lru_list));
-		list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
+		}
+		/*
+		 * Need access to lru list, first drop entry lock,
+		 * then reacquire the lock in the proper order.
+		 */
+		spin_lock(&mb_cache_spinlock);
+		if (list_empty(&ce->e_lru_list))
+			list_add_tail(&ce->e_lru_list, &mb_cache_lru_list);
+		spin_unlock(&mb_cache_spinlock);
 	}
-	spin_unlock(&mb_cache_spinlock);
+	__spin_unlock_mb_cache_entry(ce);
 	return;
 forget:
-	spin_unlock(&mb_cache_spinlock);
+	mb_assert(list_empty(&ce->e_lru_list));
 	__mb_cache_entry_forget(ce, GFP_KERNEL);
 }
 
-
 /*
  * mb_cache_shrink_scan()  memory pressure callback
  *
@@ -160,17 +254,34 @@ mb_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 
 	mb_debug("trying to free %d entries", nr_to_scan);
 	spin_lock(&mb_cache_spinlock);
-	while (nr_to_scan-- && !list_empty(&mb_cache_lru_list)) {
+	while ((nr_to_scan-- > 0) && !list_empty(&mb_cache_lru_list)) {
 		struct mb_cache_entry *ce =
 			list_entry(mb_cache_lru_list.next,
-				   struct mb_cache_entry, e_lru_list);
-		list_move_tail(&ce->e_lru_list, &free_list);
-		__mb_cache_entry_unhash(ce);
-		freed++;
+				struct mb_cache_entry, e_lru_list);
+		list_del_init(&ce->e_lru_list);
+		if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt))
+			continue;
+		spin_unlock(&mb_cache_spinlock);
+		/* Prevent any find or get operation on the entry */
+		hlist_bl_lock(ce->e_block_hash_p);
+		hlist_bl_lock(ce->e_index_hash_p);
+		/* Ignore if it is touched by a find/get */
+		if (ce->e_used || ce->e_queued || atomic_read(&ce->e_refcnt) ||
+			!list_empty(&ce->e_lru_list)) {
+			hlist_bl_unlock(ce->e_index_hash_p);
+			hlist_bl_unlock(ce->e_block_hash_p);
+			spin_lock(&mb_cache_spinlock);
+			continue;
+		}
+		__mb_cache_entry_unhash_unlock(ce);
+		list_add_tail(&ce->e_lru_list, &free_list);
+		spin_lock(&mb_cache_spinlock);
 	}
 	spin_unlock(&mb_cache_spinlock);
+
 	list_for_each_entry_safe(entry, tmp, &free_list, e_lru_list) {
 		__mb_cache_entry_forget(entry, gfp_mask);
+		freed++;
 	}
 	return freed;
 }
@@ -215,29 +326,40 @@ mb_cache_create(const char *name, int bucket_bits)
 	int n, bucket_count = 1 << bucket_bits;
 	struct mb_cache *cache = NULL;
 
+	if (!mb_cache_bg_lock) {
+		mb_cache_bg_lock = kmalloc(sizeof(struct blockgroup_lock),
+			GFP_KERNEL);
+		if (!mb_cache_bg_lock)
+			return NULL;
+		bgl_lock_init(mb_cache_bg_lock);
+	}
+
 	cache = kmalloc(sizeof(struct mb_cache), GFP_KERNEL);
 	if (!cache)
 		return NULL;
 	cache->c_name = name;
 	atomic_set(&cache->c_entry_count, 0);
 	cache->c_bucket_bits = bucket_bits;
-	cache->c_block_hash = kmalloc(bucket_count * sizeof(struct list_head),
-	                              GFP_KERNEL);
+	cache->c_block_hash = kmalloc(bucket_count *
+		sizeof(struct hlist_bl_head), GFP_KERNEL);
 	if (!cache->c_block_hash)
 		goto fail;
 	for (n=0; n<bucket_count; n++)
-		INIT_LIST_HEAD(&cache->c_block_hash[n]);
-	cache->c_index_hash = kmalloc(bucket_count * sizeof(struct list_head),
-				      GFP_KERNEL);
+		INIT_HLIST_BL_HEAD(&cache->c_block_hash[n]);
+	cache->c_index_hash = kmalloc(bucket_count *
+		sizeof(struct hlist_bl_head), GFP_KERNEL);
 	if (!cache->c_index_hash)
 		goto fail;
 	for (n=0; n<bucket_count; n++)
-		INIT_LIST_HEAD(&cache->c_index_hash[n]);
-	cache->c_entry_cache = kmem_cache_create(name,
-		sizeof(struct mb_cache_entry), 0,
-		SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
-	if (!cache->c_entry_cache)
-		goto fail2;
+		INIT_HLIST_BL_HEAD(&cache->c_index_hash[n]);
+	if (!mb_cache_kmem_cache) {
+		mb_cache_kmem_cache = kmem_cache_create(name,
+			sizeof(struct mb_cache_entry), 0,
+			SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD, NULL);
+		if (!mb_cache_kmem_cache)
+			goto fail2;
+	}
+	cache->c_entry_cache = mb_cache_kmem_cache;
 
 	/*
 	 * Set an upper limit on the number of cache entries so that the hash
@@ -273,21 +395,47 @@ void
 mb_cache_shrink(struct block_device *bdev)
 {
 	LIST_HEAD(free_list);
-	struct list_head *l, *ltmp;
+	struct list_head *l;
+	struct mb_cache_entry *ce, *tmp;
 
+	l = &mb_cache_lru_list;
 	spin_lock(&mb_cache_spinlock);
-	list_for_each_safe(l, ltmp, &mb_cache_lru_list) {
-		struct mb_cache_entry *ce =
-			list_entry(l, struct mb_cache_entry, e_lru_list);
+	while (!list_is_last(l, &mb_cache_lru_list)) {
+		l = l->next;
+		ce = list_entry(l, struct mb_cache_entry, e_lru_list);
 		if (ce->e_bdev == bdev) {
-			list_move_tail(&ce->e_lru_list, &free_list);
-			__mb_cache_entry_unhash(ce);
+			list_del_init(&ce->e_lru_list);
+			if (ce->e_used || ce->e_queued ||
+				atomic_read(&ce->e_refcnt))
+				continue;
+			spin_unlock(&mb_cache_spinlock);
+			/*
+			 * Prevent any find or get operation on the entry.
+			 */
+			hlist_bl_lock(ce->e_block_hash_p);
+			hlist_bl_lock(ce->e_index_hash_p);
+			/* Ignore if it is touched by a find/get */
+			if (ce->e_used || ce->e_queued ||
+				atomic_read(&ce->e_refcnt) ||
+				!list_empty(&ce->e_lru_list)) {
+				hlist_bl_unlock(ce->e_index_hash_p);
+				hlist_bl_unlock(ce->e_block_hash_p);
+				l = &mb_cache_lru_list;
+				spin_lock(&mb_cache_spinlock);
+				continue;
+			}
+			__mb_cache_entry_unhash_unlock(ce);
+			mb_assert(!(ce->e_used || ce->e_queued ||
+				atomic_read(&ce->e_refcnt)));
+			list_add_tail(&ce->e_lru_list, &free_list);
+			l = &mb_cache_lru_list;
+			spin_lock(&mb_cache_spinlock);
 		}
 	}
 	spin_unlock(&mb_cache_spinlock);
-	list_for_each_safe(l, ltmp, &free_list) {
-		__mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
-						   e_lru_list), GFP_KERNEL);
+
+	list_for_each_entry_safe(ce, tmp, &free_list, e_lru_list) {
+		__mb_cache_entry_forget(ce, GFP_KERNEL);
 	}
 }
 
@@ -303,23 +451,27 @@ void
 mb_cache_destroy(struct mb_cache *cache)
 {
 	LIST_HEAD(free_list);
-	struct list_head *l, *ltmp;
+	struct mb_cache_entry *ce, *tmp;
 
 	spin_lock(&mb_cache_spinlock);
-	list_for_each_safe(l, ltmp, &mb_cache_lru_list) {
-		struct mb_cache_entry *ce =
-			list_entry(l, struct mb_cache_entry, e_lru_list);
-		if (ce->e_cache == cache) {
+	list_for_each_entry_safe(ce, tmp, &mb_cache_lru_list, e_lru_list) {
+		if (ce->e_cache == cache)
 			list_move_tail(&ce->e_lru_list, &free_list);
-			__mb_cache_entry_unhash(ce);
-		}
 	}
 	list_del(&cache->c_cache_list);
 	spin_unlock(&mb_cache_spinlock);
 
-	list_for_each_safe(l, ltmp, &free_list) {
-		__mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
-						   e_lru_list), GFP_KERNEL);
+	list_for_each_entry_safe(ce, tmp, &free_list, e_lru_list) {
+		list_del_init(&ce->e_lru_list);
+		/*
+		 * Prevent any find or get operation on the entry.
+		 */
+		hlist_bl_lock(ce->e_block_hash_p);
+		hlist_bl_lock(ce->e_index_hash_p);
+		mb_assert(!(ce->e_used || ce->e_queued ||
+			atomic_read(&ce->e_refcnt)));
+		__mb_cache_entry_unhash_unlock(ce);
+		__mb_cache_entry_forget(ce, GFP_KERNEL);
 	}
 
 	if (atomic_read(&cache->c_entry_count) > 0) {
@@ -328,8 +480,10 @@ mb_cache_destroy(struct mb_cache *cache)
 			  atomic_read(&cache->c_entry_count));
 	}
 
-	kmem_cache_destroy(cache->c_entry_cache);
-
+	if (list_empty(&mb_cache_list)) {
+		kmem_cache_destroy(mb_cache_kmem_cache);
+		mb_cache_kmem_cache = NULL;
+	}
 	kfree(cache->c_index_hash);
 	kfree(cache->c_block_hash);
 	kfree(cache);
@@ -346,28 +500,61 @@ mb_cache_destroy(struct mb_cache *cache)
 struct mb_cache_entry *
 mb_cache_entry_alloc(struct mb_cache *cache, gfp_t gfp_flags)
 {
-	struct mb_cache_entry *ce = NULL;
+	struct mb_cache_entry *ce;
 
 	if (atomic_read(&cache->c_entry_count) >= cache->c_max_entries) {
+		struct list_head *l;
+
+		l = &mb_cache_lru_list;
 		spin_lock(&mb_cache_spinlock);
-		if (!list_empty(&mb_cache_lru_list)) {
-			ce = list_entry(mb_cache_lru_list.next,
-					struct mb_cache_entry, e_lru_list);
-			list_del_init(&ce->e_lru_list);
-			__mb_cache_entry_unhash(ce);
+		while (!list_is_last(l, &mb_cache_lru_list)) {
+			l = l->next;
+			ce = list_entry(l, struct mb_cache_entry, e_lru_list);
+			if (ce->e_cache == cache) {
+				list_del_init(&ce->e_lru_list);
+				if (ce->e_used || ce->e_queued ||
+					atomic_read(&ce->e_refcnt))
+					continue;
+				spin_unlock(&mb_cache_spinlock);
+				/*
+				 * Prevent any find or get operation on the
+				 * entry.
+				 */
+				hlist_bl_lock(ce->e_block_hash_p);
+				hlist_bl_lock(ce->e_index_hash_p);
+				/* Ignore if it is touched by a find/get */
+				if (ce->e_used || ce->e_queued ||
+					atomic_read(&ce->e_refcnt) ||
+					!list_empty(&ce->e_lru_list)) {
+					hlist_bl_unlock(ce->e_index_hash_p);
+					hlist_bl_unlock(ce->e_block_hash_p);
+					l = &mb_cache_lru_list;
+					spin_lock(&mb_cache_spinlock);
+					continue;
+				}
+				mb_assert(list_empty(&ce->e_lru_list));
+				mb_assert(!(ce->e_used || ce->e_queued ||
+					atomic_read(&ce->e_refcnt)));
+				__mb_cache_entry_unhash_unlock(ce);
+				goto found;
+			}
 		}
 		spin_unlock(&mb_cache_spinlock);
 	}
-	if (!ce) {
-		ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
-		if (!ce)
-			return NULL;
-		atomic_inc(&cache->c_entry_count);
-		INIT_LIST_HEAD(&ce->e_lru_list);
-		INIT_LIST_HEAD(&ce->e_block_list);
-		ce->e_cache = cache;
-		ce->e_queued = 0;
-	}
+
+	ce = kmem_cache_alloc(cache->c_entry_cache, gfp_flags);
+	if (!ce)
+		return NULL;
+	atomic_inc(&cache->c_entry_count);
+	INIT_LIST_HEAD(&ce->e_lru_list);
+	INIT_HLIST_BL_NODE(&ce->e_block_list);
+	INIT_HLIST_BL_NODE(&ce->e_index.o_list);
+	ce->e_cache = cache;
+	ce->e_queued = 0;
+	atomic_set(&ce->e_refcnt, 0);
+found:
+	ce->e_block_hash_p = &cache->c_block_hash[0];
+	ce->e_index_hash_p = &cache->c_index_hash[0];
 	ce->e_used = 1 + MB_CACHE_WRITER;
 	return ce;
 }
@@ -393,29 +580,38 @@ mb_cache_entry_insert(struct mb_cache_entry *ce, struct block_device *bdev,
 {
 	struct mb_cache *cache = ce->e_cache;
 	unsigned int bucket;
-	struct list_head *l;
-	int error = -EBUSY;
+	struct hlist_bl_node *l;
+	struct hlist_bl_head *block_hash_p;
+	struct hlist_bl_head *index_hash_p;
+	struct mb_cache_entry *lce;
 
+	mb_assert(ce);
 	bucket = hash_long((unsigned long)bdev + (block & 0xffffffff), 
 			   cache->c_bucket_bits);
-	spin_lock(&mb_cache_spinlock);
-	list_for_each_prev(l, &cache->c_block_hash[bucket]) {
-		struct mb_cache_entry *ce =
-			list_entry(l, struct mb_cache_entry, e_block_list);
-		if (ce->e_bdev == bdev && ce->e_block == block)
-			goto out;
+	block_hash_p = &cache->c_block_hash[bucket];
+	hlist_bl_lock(block_hash_p);
+	hlist_bl_for_each_entry(lce, l, block_hash_p, e_block_list) {
+		if (lce->e_bdev == bdev && lce->e_block == block) {
+			hlist_bl_unlock(block_hash_p);
+			return -EBUSY;
+		}
 	}
-	__mb_cache_entry_unhash(ce);
+	mb_assert(!__mb_cache_entry_is_block_hashed(ce));
+	__mb_cache_entry_unhash_block(ce);
+	__mb_cache_entry_unhash_index(ce);
 	ce->e_bdev = bdev;
 	ce->e_block = block;
-	list_add(&ce->e_block_list, &cache->c_block_hash[bucket]);
+	ce->e_block_hash_p = block_hash_p;
 	ce->e_index.o_key = key;
+	hlist_bl_add_head(&ce->e_block_list, block_hash_p);
+	hlist_bl_unlock(block_hash_p);
 	bucket = hash_long(key, cache->c_bucket_bits);
-	list_add(&ce->e_index.o_list, &cache->c_index_hash[bucket]);
-	error = 0;
-out:
-	spin_unlock(&mb_cache_spinlock);
-	return error;
+	index_hash_p = &cache->c_index_hash[bucket];
+	hlist_bl_lock(index_hash_p);
+	ce->e_index_hash_p = index_hash_p;
+	hlist_bl_add_head(&ce->e_index.o_list, index_hash_p);
+	hlist_bl_unlock(index_hash_p);
+	return 0;
 }
 
 
@@ -429,24 +625,26 @@ out:
 void
 mb_cache_entry_release(struct mb_cache_entry *ce)
 {
-	spin_lock(&mb_cache_spinlock);
-	__mb_cache_entry_release_unlock(ce);
+	__mb_cache_entry_release(ce);
 }
 
 
 /*
  * mb_cache_entry_free()
  *
- * This is equivalent to the sequence mb_cache_entry_takeout() --
- * mb_cache_entry_release().
  */
 void
 mb_cache_entry_free(struct mb_cache_entry *ce)
 {
-	spin_lock(&mb_cache_spinlock);
+	mb_assert(ce);
 	mb_assert(list_empty(&ce->e_lru_list));
-	__mb_cache_entry_unhash(ce);
-	__mb_cache_entry_release_unlock(ce);
+	hlist_bl_lock(ce->e_index_hash_p);
+	__mb_cache_entry_unhash_index(ce);
+	hlist_bl_unlock(ce->e_index_hash_p);
+	hlist_bl_lock(ce->e_block_hash_p);
+	__mb_cache_entry_unhash_block(ce);
+	hlist_bl_unlock(ce->e_block_hash_p);
+	__mb_cache_entry_release(ce);
 }
 
 
@@ -463,84 +661,110 @@ mb_cache_entry_get(struct mb_cache *cache, struct block_device *bdev,
 		   sector_t block)
 {
 	unsigned int bucket;
-	struct list_head *l;
+	struct hlist_bl_node *l;
 	struct mb_cache_entry *ce;
+	struct hlist_bl_head *block_hash_p;
 
 	bucket = hash_long((unsigned long)bdev + (block & 0xffffffff),
 			   cache->c_bucket_bits);
-	spin_lock(&mb_cache_spinlock);
-	list_for_each(l, &cache->c_block_hash[bucket]) {
-		ce = list_entry(l, struct mb_cache_entry, e_block_list);
+	block_hash_p = &cache->c_block_hash[bucket];
+	/* First serialize access to the block corresponding hash chain. */
+	hlist_bl_lock(block_hash_p);
+	hlist_bl_for_each_entry(ce, l, block_hash_p, e_block_list) {
+		mb_assert(ce->e_block_hash_p == block_hash_p);
 		if (ce->e_bdev == bdev && ce->e_block == block) {
-			DEFINE_WAIT(wait);
+			/*
+			 * Prevent a free from removing the entry.
+			 */
+			atomic_inc(&ce->e_refcnt);
+			hlist_bl_unlock(block_hash_p);
+			__spin_lock_mb_cache_entry(ce);
+			atomic_dec(&ce->e_refcnt);
+			if (ce->e_used > 0) {
+				DEFINE_WAIT(wait);
+				while (ce->e_used > 0) {
+					ce->e_queued++;
+					prepare_to_wait(&mb_cache_queue, &wait,
+							TASK_UNINTERRUPTIBLE);
+					__spin_unlock_mb_cache_entry(ce);
+					schedule();
+					__spin_lock_mb_cache_entry(ce);
+					ce->e_queued--;
+				}
+				finish_wait(&mb_cache_queue, &wait);
+			}
+			ce->e_used += 1 + MB_CACHE_WRITER;
+			__spin_unlock_mb_cache_entry(ce);
 
-			if (!list_empty(&ce->e_lru_list))
+			if (!list_empty(&ce->e_lru_list)) {
+				spin_lock(&mb_cache_spinlock);
 				list_del_init(&ce->e_lru_list);
-
-			while (ce->e_used > 0) {
-				ce->e_queued++;
-				prepare_to_wait(&mb_cache_queue, &wait,
-						TASK_UNINTERRUPTIBLE);
 				spin_unlock(&mb_cache_spinlock);
-				schedule();
-				spin_lock(&mb_cache_spinlock);
-				ce->e_queued--;
 			}
-			finish_wait(&mb_cache_queue, &wait);
-			ce->e_used += 1 + MB_CACHE_WRITER;
-
-			if (!__mb_cache_entry_is_hashed(ce)) {
-				__mb_cache_entry_release_unlock(ce);
+			if (!__mb_cache_entry_is_block_hashed(ce)) {
+				__mb_cache_entry_release(ce);
 				return NULL;
 			}
-			goto cleanup;
+			return ce;
 		}
 	}
-	ce = NULL;
-
-cleanup:
-	spin_unlock(&mb_cache_spinlock);
-	return ce;
+	hlist_bl_unlock(block_hash_p);
+	return NULL;
 }
 
 #if !defined(MB_CACHE_INDEXES_COUNT) || (MB_CACHE_INDEXES_COUNT > 0)
 
 static struct mb_cache_entry *
-__mb_cache_entry_find(struct list_head *l, struct list_head *head,
+__mb_cache_entry_find(struct hlist_bl_node *l, struct hlist_bl_head *head,
 		      struct block_device *bdev, unsigned int key)
 {
-	while (l != head) {
+
+	/* The index hash chain is alredy acquire by caller. */
+	while (l != NULL) {
 		struct mb_cache_entry *ce =
-			list_entry(l, struct mb_cache_entry, e_index.o_list);
+			hlist_bl_entry(l, struct mb_cache_entry,
+				e_index.o_list);
+		mb_assert(ce->e_index_hash_p == head);
 		if (ce->e_bdev == bdev && ce->e_index.o_key == key) {
-			DEFINE_WAIT(wait);
-
-			if (!list_empty(&ce->e_lru_list))
-				list_del_init(&ce->e_lru_list);
-
+			/*
+			 * Prevent a free from removing the entry.
+			 */
+			atomic_inc(&ce->e_refcnt);
+			hlist_bl_unlock(head);
+			__spin_lock_mb_cache_entry(ce);
+			atomic_dec(&ce->e_refcnt);
+			ce->e_used++;
 			/* Incrementing before holding the lock gives readers
 			   priority over writers. */
-			ce->e_used++;
-			while (ce->e_used >= MB_CACHE_WRITER) {
-				ce->e_queued++;
-				prepare_to_wait(&mb_cache_queue, &wait,
-						TASK_UNINTERRUPTIBLE);
-				spin_unlock(&mb_cache_spinlock);
-				schedule();
-				spin_lock(&mb_cache_spinlock);
-				ce->e_queued--;
+			if (ce->e_used >= MB_CACHE_WRITER) {
+				DEFINE_WAIT(wait);
+
+				while (ce->e_used >= MB_CACHE_WRITER) {
+					ce->e_queued++;
+					prepare_to_wait(&mb_cache_queue, &wait,
+							TASK_UNINTERRUPTIBLE);
+					__spin_unlock_mb_cache_entry(ce);
+					schedule();
+					__spin_lock_mb_cache_entry(ce);
+					ce->e_queued--;
+				}
+				finish_wait(&mb_cache_queue, &wait);
 			}
-			finish_wait(&mb_cache_queue, &wait);
-
-			if (!__mb_cache_entry_is_hashed(ce)) {
-				__mb_cache_entry_release_unlock(ce);
+			__spin_unlock_mb_cache_entry(ce);
+			if (!list_empty(&ce->e_lru_list)) {
 				spin_lock(&mb_cache_spinlock);
+				list_del_init(&ce->e_lru_list);
+				spin_unlock(&mb_cache_spinlock);
+			}
+			if (!__mb_cache_entry_is_block_hashed(ce)) {
+				__mb_cache_entry_release(ce);
 				return ERR_PTR(-EAGAIN);
 			}
 			return ce;
 		}
 		l = l->next;
 	}
+	hlist_bl_unlock(head);
 	return NULL;
 }
 
@@ -562,13 +786,17 @@ mb_cache_entry_find_first(struct mb_cache *cache, struct block_device *bdev,
 			  unsigned int key)
 {
 	unsigned int bucket = hash_long(key, cache->c_bucket_bits);
-	struct list_head *l;
-	struct mb_cache_entry *ce;
-
-	spin_lock(&mb_cache_spinlock);
-	l = cache->c_index_hash[bucket].next;
-	ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key);
-	spin_unlock(&mb_cache_spinlock);
+	struct hlist_bl_node *l;
+	struct mb_cache_entry *ce = NULL;
+	struct hlist_bl_head *index_hash_p;
+
+	index_hash_p = &cache->c_index_hash[bucket];
+	hlist_bl_lock(index_hash_p);
+	if (!hlist_bl_empty(index_hash_p)) {
+		l = hlist_bl_first(index_hash_p);
+		ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
+	} else
+		hlist_bl_unlock(index_hash_p);
 	return ce;
 }
 
@@ -597,13 +825,17 @@ mb_cache_entry_find_next(struct mb_cache_entry *prev,
 {
 	struct mb_cache *cache = prev->e_cache;
 	unsigned int bucket = hash_long(key, cache->c_bucket_bits);
-	struct list_head *l;
+	struct hlist_bl_node *l;
 	struct mb_cache_entry *ce;
+	struct hlist_bl_head *index_hash_p;
 
-	spin_lock(&mb_cache_spinlock);
+	index_hash_p = &cache->c_index_hash[bucket];
+	mb_assert(prev->e_index_hash_p == index_hash_p);
+	hlist_bl_lock(index_hash_p);
+	mb_assert(!hlist_bl_empty(index_hash_p));
 	l = prev->e_index.o_list.next;
-	ce = __mb_cache_entry_find(l, &cache->c_index_hash[bucket], bdev, key);
-	__mb_cache_entry_release_unlock(prev);
+	ce = __mb_cache_entry_find(l, index_hash_p, bdev, key);
+	__mb_cache_entry_release(prev);
 	return ce;
 }