1 files changed, 29 insertions, 26 deletions

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index a11a92ee2d3..7b2f0c3e792 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;
@@ -120,8 +118,6 @@ 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;
@@ -130,14 +126,26 @@ struct extent_buffer {
         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,