mbcache: make mbcache naming more generic

Make names more generic so that mbcache usage is not limited to
block sharing. In a subsequent patch in the series
("ext4: xattr inode deduplication"), we start using the mbcache code
for sharing xattr inodes. With that patch, old mb_cache_entry.e_block
field could be holding either a block number or an inode number.

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

4 files changed, 40 insertions, 42 deletions

diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index fbdb8f171893..1e5f76070580 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -493,8 +493,8 @@ bad_block:		ext2_error(sb, "ext2_xattr_set",
                          * This must happen under buffer lock for
                          * ext2_xattr_set2() to reliably detect modified block
                          */
-                        mb_cache_entry_delete_block(EXT2_SB(sb)->s_mb_cache,
-                                                    hash, bh->b_blocknr);
+                        mb_cache_entry_delete(EXT2_SB(sb)->s_mb_cache, hash,
+                                              bh->b_blocknr);
 
                         /* keep the buffer locked while modifying it. */
                 } else {
@@ -721,8 +721,8 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
                          * This must happen under buffer lock for
                          * ext2_xattr_set2() to reliably detect freed block
                          */
-                        mb_cache_entry_delete_block(ext2_mb_cache,
-                                                    hash, old_bh->b_blocknr);
+                        mb_cache_entry_delete(ext2_mb_cache, hash,
+                                              old_bh->b_blocknr);
                         /* Free the old block. */
                         ea_bdebug(old_bh, "freeing");
                         ext2_free_blocks(inode, old_bh->b_blocknr, 1);
@@ -795,8 +795,8 @@ ext2_xattr_delete_inode(struct inode *inode)
                  * This must happen under buffer lock for ext2_xattr_set2() to
                  * reliably detect freed block
                  */
-                mb_cache_entry_delete_block(EXT2_SB(inode->i_sb)->s_mb_cache,
-                                            hash, bh->b_blocknr);
+                mb_cache_entry_delete(EXT2_SB(inode->i_sb)->s_mb_cache, hash,
+                                      bh->b_blocknr);
                 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1);
                 get_bh(bh);
                 bforget(bh);
@@ -907,11 +907,11 @@ again:
         while (ce) {
                 struct buffer_head *bh;
 
-                bh = sb_bread(inode->i_sb, ce->e_block);
+                bh = sb_bread(inode->i_sb, ce->e_value);
                 if (!bh) {
                         ext2_error(inode->i_sb, "ext2_xattr_cache_find",
                                 "inode %ld: block %ld read error",
-                                inode->i_ino, (unsigned long) ce->e_block);
+                                inode->i_ino, (unsigned long) ce->e_value);
                 } else {
                         lock_buffer(bh);
                         /*
@@ -931,7 +931,7 @@ again:
                         } else if (le32_to_cpu(HDR(bh)->h_refcount) >
                                    EXT2_XATTR_REFCOUNT_MAX) {
                                 ea_idebug(inode, "block %ld refcount %d>%d",
-                                          (unsigned long) ce->e_block,
+                                          (unsigned long) ce->e_value,
                                           le32_to_cpu(HDR(bh)->h_refcount),
                                           EXT2_XATTR_REFCOUNT_MAX);
                         } else if (!ext2_xattr_cmp(header, HDR(bh))) {
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index fed54001c9e6..85da7792afd0 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -678,7 +678,7 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode,
                  * This must happen under buffer lock for
                  * ext4_xattr_block_set() to reliably detect freed block
                  */
-                mb_cache_entry_delete_block(ext4_mb_cache, hash, bh->b_blocknr);
+                mb_cache_entry_delete(ext4_mb_cache, hash, bh->b_blocknr);
                 get_bh(bh);
                 unlock_buffer(bh);
                 ext4_free_blocks(handle, inode, bh, 0, 1,
@@ -1113,8 +1113,8 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
                          * ext4_xattr_block_set() to reliably detect modified
                          * block
                          */
-                        mb_cache_entry_delete_block(ext4_mb_cache, hash,
-                                                    bs->bh->b_blocknr);
+                        mb_cache_entry_delete(ext4_mb_cache, hash,
+                                              bs->bh->b_blocknr);
                         ea_bdebug(bs->bh, "modifying in-place");
                         error = ext4_xattr_set_entry(i, s, handle, inode);
                         if (!error) {
@@ -2236,10 +2236,10 @@ ext4_xattr_cache_find(struct inode *inode, struct ext4_xattr_header *header,
         while (ce) {
                 struct buffer_head *bh;
 
-                bh = sb_bread(inode->i_sb, ce->e_block);
+                bh = sb_bread(inode->i_sb, ce->e_value);
                 if (!bh) {
                         EXT4_ERROR_INODE(inode, "block %lu read error",
-                                         (unsigned long) ce->e_block);
+                                         (unsigned long)ce->e_value);
                 } else if (ext4_xattr_cmp(header, BHDR(bh)) == 0) {
                         *pce = ce;
                         return bh;
diff --git a/fs/mbcache.c b/fs/mbcache.c
index b19be429d655..45a8d52dc991 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -10,7 +10,7 @@
 /*
  * Mbcache is a simple key-value store. Keys need not be unique, however
  * key-value pairs are expected to be unique (we use this fact in
- * mb_cache_entry_delete_block()).
+ * mb_cache_entry_delete()).
  *
  * Ext2 and ext4 use this cache for deduplication of extended attribute blocks.
  * They use hash of a block contents as a key and block number as a value.
@@ -62,15 +62,15 @@ static inline struct hlist_bl_head *mb_cache_entry_head(struct mb_cache *cache,
  * @cache - cache where the entry should be created
  * @mask - gfp mask with which the entry should be allocated
  * @key - key of the entry
- * @block - block that contains data
- * @reusable - is the block reusable by other inodes?
+ * @value - value of the entry
+ * @reusable - is the entry reusable by others?
  *
- * Creates entry in @cache with key @key and records that data is stored in
- * block @block. The function returns -EBUSY if entry with the same key
- * and for the same block already exists in cache. Otherwise 0 is returned.
+ * Creates entry in @cache with key @key and value @value. The function returns
+ * -EBUSY if entry with the same key and value already exists in cache.
+ * Otherwise 0 is returned.
  */
 int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
-                          sector_t block, bool reusable)
+                          u64 value, bool reusable)
 {
         struct mb_cache_entry *entry, *dup;
         struct hlist_bl_node *dup_node;
@@ -91,12 +91,12 @@ int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
         /* One ref for hash, one ref returned */
         atomic_set(&entry->e_refcnt, 1);
         entry->e_key = key;
-        entry->e_block = block;
+        entry->e_value = value;
         entry->e_reusable = reusable;
         head = mb_cache_entry_head(cache, key);
         hlist_bl_lock(head);
         hlist_bl_for_each_entry(dup, dup_node, head, e_hash_list) {
-                if (dup->e_key == key && dup->e_block == block) {
+                if (dup->e_key == key && dup->e_value == value) {
                         hlist_bl_unlock(head);
                         kmem_cache_free(mb_entry_cache, entry);
                         return -EBUSY;
@@ -187,13 +187,13 @@ struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,
 EXPORT_SYMBOL(mb_cache_entry_find_next);
 
 /*
- * mb_cache_entry_get - get a cache entry by block number (and key)
+ * mb_cache_entry_get - get a cache entry by value (and key)
  * @cache - cache we work with
- * @key - key of block number @block
- * @block - block number
+ * @key - key
+ * @value - value
  */
 struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
-                                          sector_t block)
+                                          u64 value)
 {
         struct hlist_bl_node *node;
         struct hlist_bl_head *head;
@@ -202,7 +202,7 @@ struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
         head = mb_cache_entry_head(cache, key);
         hlist_bl_lock(head);
         hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
-                if (entry->e_key == key && entry->e_block == block) {
+                if (entry->e_key == key && entry->e_value == value) {
                         atomic_inc(&entry->e_refcnt);
                         goto out;
                 }
@@ -214,15 +214,14 @@ out:
 }
 EXPORT_SYMBOL(mb_cache_entry_get);
 
-/* mb_cache_entry_delete_block - remove information about block from cache
+/* mb_cache_entry_delete - remove a cache entry
  * @cache - cache we work with
- * @key - key of block @block
- * @block - block number
+ * @key - key
+ * @value - value
  *
- * Remove entry from cache @cache with key @key with data stored in @block.
+ * Remove entry from cache @cache with key @key and value @value.
  */
-void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key,
-                                 sector_t block)
+void mb_cache_entry_delete(struct mb_cache *cache, u32 key, u64 value)
 {
         struct hlist_bl_node *node;
         struct hlist_bl_head *head;
@@ -231,7 +230,7 @@ void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key,
         head = mb_cache_entry_head(cache, key);
         hlist_bl_lock(head);
         hlist_bl_for_each_entry(entry, node, head, e_hash_list) {
-                if (entry->e_key == key && entry->e_block == block) {
+                if (entry->e_key == key && entry->e_value == value) {
                         /* We keep hash list reference to keep entry alive */
                         hlist_bl_del_init(&entry->e_hash_list);
                         hlist_bl_unlock(head);
@@ -248,7 +247,7 @@ void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key,
         }
         hlist_bl_unlock(head);
 }
-EXPORT_SYMBOL(mb_cache_entry_delete_block);
+EXPORT_SYMBOL(mb_cache_entry_delete);
 
 /* mb_cache_entry_touch - cache entry got used
  * @cache - cache the entry belongs to
diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h
index 86c9a8b480c5..e1bc73414983 100644
--- a/include/linux/mbcache.h
+++ b/include/linux/mbcache.h
@@ -19,15 +19,15 @@ struct mb_cache_entry {
         u32                     e_key;
         u32                     e_referenced:1;
         u32                     e_reusable:1;
-        /* Block number of hashed block - stable during lifetime of the entry */
-        sector_t                e_block;
+        /* User provided value - stable during lifetime of the entry */
+        u64                     e_value;
 };
 
 struct mb_cache *mb_cache_create(int bucket_bits);
 void mb_cache_destroy(struct mb_cache *cache);
 
 int mb_cache_entry_create(struct mb_cache *cache, gfp_t mask, u32 key,
-                          sector_t block, bool reusable);
+                          u64 value, bool reusable);
 void __mb_cache_entry_free(struct mb_cache_entry *entry);
 static inline int mb_cache_entry_put(struct mb_cache *cache,
                                      struct mb_cache_entry *entry)
@@ -38,10 +38,9 @@ static inline int mb_cache_entry_put(struct mb_cache *cache,
         return 1;
 }
 
-void mb_cache_entry_delete_block(struct mb_cache *cache, u32 key,
-                                  sector_t block);
+void mb_cache_entry_delete(struct mb_cache *cache, u32 key, u64 value);
 struct mb_cache_entry *mb_cache_entry_get(struct mb_cache *cache, u32 key,
-                                          sector_t block);
+                                          u64 value);
 struct mb_cache_entry *mb_cache_entry_find_first(struct mb_cache *cache,
                                                  u32 key);
 struct mb_cache_entry *mb_cache_entry_find_next(struct mb_cache *cache,