btrfs: switch extent_buffer write_locks from atomic to int

The write_locks is either 0 or 1 and always updated under the lock,
so we don't need the atomic_t semantics.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -4879,7 +4879,7 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
 	eb->spinning_writers = 0;
 	atomic_set(&eb->spinning_readers, 0);
 	atomic_set(&eb->read_locks, 0);
-	atomic_set(&eb->write_locks, 0);
+	eb->write_locks = 0;
 #endif
 
 	return eb;

fs/btrfs/extent_io.h

@@ -190,7 +190,7 @@ struct extent_buffer {
 	int spinning_writers;
 	atomic_t spinning_readers;
 	atomic_t read_locks;
-	atomic_t write_locks;
+	int write_locks;
 	struct list_head leak_list;
 #endif
 };

fs/btrfs/locking.c

@@ -58,17 +58,17 @@ static void btrfs_assert_tree_read_locked(struct extent_buffer *eb)
 
 static void btrfs_assert_tree_write_locks_get(struct extent_buffer *eb)
 {
-	atomic_inc(&eb->write_locks);
+	eb->write_locks++;
 }
 
 static void btrfs_assert_tree_write_locks_put(struct extent_buffer *eb)
 {
-	atomic_dec(&eb->write_locks);
+	eb->write_locks--;
 }
 
 void btrfs_assert_tree_locked(struct extent_buffer *eb)
 {
-	BUG_ON(!atomic_read(&eb->write_locks));
+	BUG_ON(!eb->write_locks);
 }
 
 #else

fs/btrfs/print-tree.c

@@ -153,7 +153,7 @@ static void print_eb_refs_lock(struct extent_buffer *eb)
 #ifdef CONFIG_BTRFS_DEBUG
 	btrfs_info(eb->fs_info,
 "refs %u lock (w:%d r:%d bw:%d br:%d sw:%d sr:%d) lock_owner %u current %u",
-		   atomic_read(&eb->refs), atomic_read(&eb->write_locks),
+		   atomic_read(&eb->refs), eb->write_locks,
 		   atomic_read(&eb->read_locks),
 		   eb->blocking_writers,
 		   atomic_read(&eb->blocking_readers),