Btrfs: get right arguments for btrfs_wait_ordered_range

btrfs_wait_ordered_range expects for 'len' instead of 'end'.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 9ab1bed..d2df981 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1562,7 +1562,7 @@
 	 * range being left.
 	 */
 	atomic_inc(&root->log_batch);
-	btrfs_wait_ordered_range(inode, start, end);
+	btrfs_wait_ordered_range(inode, start, end - start + 1);
 	atomic_inc(&root->log_batch);
 
 	/*