1 files changed, 30 insertions, 27 deletions

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 4e8445a4757c..7b2f0c3e7929 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -76,15 +76,15 @@ struct extent_io_ops {
 				    struct extent_state *state);
 	int (*writepage_end_io_hook)(struct page *page, u64 start, u64 end,
 				      struct extent_state *state, int uptodate);
-	int (*set_bit_hook)(struct inode *inode, struct extent_state *state,
-			    int *bits);
-	int (*clear_bit_hook)(struct inode *inode, struct extent_state *state,
-			      int *bits);
-	int (*merge_extent_hook)(struct inode *inode,
-				 struct extent_state *new,
-				 struct extent_state *other);
-	int (*split_extent_hook)(struct inode *inode,
-				 struct extent_state *orig, u64 split);
+	void (*set_bit_hook)(struct inode *inode, struct extent_state *state,
+			     int *bits);
+	void (*clear_bit_hook)(struct inode *inode, struct extent_state *state,
+			       int *bits);
+	void (*merge_extent_hook)(struct inode *inode,
+				  struct extent_state *new,
+				  struct extent_state *other);
+	void (*split_extent_hook)(struct inode *inode,
+				  struct extent_state *orig, u64 split);
 	int (*write_cache_pages_lock_hook)(struct page *page);
 };
 
@@ -108,8 +108,6 @@ struct extent_state {
 	wait_queue_head_t wq;
 	atomic_t refs;
 	unsigned long state;
-	u64 split_start;
-	u64 split_end;
 
 	/* for use by the FS */
 	u64 private;
@@ -120,24 +118,34 @@ struct extent_state {
 struct extent_buffer {
 	u64 start;
 	unsigned long len;
-	char *map_token;
-	char *kaddr;
 	unsigned long map_start;
 	unsigned long map_len;
 	struct page *first_page;
 	unsigned long bflags;
-	atomic_t refs;
 	struct list_head leak_list;
 	struct rcu_head rcu_head;
+	atomic_t refs;
 
-	/* the spinlock is used to protect most operations */
-	spinlock_t lock;
+	/* count of read lock holders on the extent buffer */
+	atomic_t write_locks;
+	atomic_t read_locks;
+	atomic_t blocking_writers;
+	atomic_t blocking_readers;
+	atomic_t spinning_readers;
+	atomic_t spinning_writers;
+
+	/* protects write locks */
+	rwlock_t lock;
 
-	/*
-	 * when we keep the lock held while blocking, waiters go onto
-	 * the wq
+	/* readers use lock_wq while they wait for the write
+	 * lock holders to unlock
 	 */
-	wait_queue_head_t lock_wq;
+	wait_queue_head_t write_lock_wq;
+
+	/* writers use read_lock_wq while they wait for readers
+	 * to unlock
+	 */
+	wait_queue_head_t read_lock_wq;
 };
 
 static inline void extent_set_compress_type(unsigned long *bio_flags,
@@ -279,15 +287,10 @@ int clear_extent_buffer_uptodate(struct extent_io_tree *tree,
 int extent_buffer_uptodate(struct extent_io_tree *tree,
 			   struct extent_buffer *eb,
 			   struct extent_state *cached_state);
-int map_extent_buffer(struct extent_buffer *eb, unsigned long offset,
-		      unsigned long min_len, char **token, char **map,
-		      unsigned long *map_start,
-		      unsigned long *map_len, int km);
 int map_private_extent_buffer(struct extent_buffer *eb, unsigned long offset,
-		      unsigned long min_len, char **token, char **map,
+		      unsigned long min_len, char **map,
 		      unsigned long *map_start,
-		      unsigned long *map_len, int km);
-void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km);
+		      unsigned long *map_len);
 int extent_range_uptodate(struct extent_io_tree *tree,
 			  u64 start, u64 end);
 int extent_clear_unlock_delalloc(struct inode *inode,