Btrfs: read lock extent buffer while walking backrefs

Before processing the extent buffer, acquire a read lock on it, so that we're safe against concurrent updates on the extent buffer. Signed-off-by: Filipe Manana <[email protected]> Signed-off-by: Chris Mason <[email protected]>
mrcsosa · Aug 15, 2014 · 6f7ff6d · 6f7ff6d
1 parent e339a6b
commit 6f7ff6d
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
@@ -1001,8 +1001,11 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
 					ret = -EIO;
 					goto out;
 				}
+				btrfs_tree_read_lock(eb);
+				btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
 				ret = find_extent_in_eb(eb, bytenr,
 							*extent_item_pos, &eie);
+				btrfs_tree_read_unlock_blocking(eb);
 				free_extent_buffer(eb);
 				if (ret < 0)
 					goto out;