btrfs: do not delete mismatched root refs

btrfs_del_root_ref() will simply WARN_ON() if the ref doesn't match in
any way, and then continue to delete the reference.  This shouldn't
happen, we have these values because there's more to the reference than
the original root and the sub root.  If any of these checks fail, return
-ENOENT.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 3b17b647d002f2c5cb747ade373500a0921f08b4..612411c74550f5d1776c318269249abb0b7953fc 100644 (file)
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -376,11 +376,13 @@ again:
                leaf = path->nodes[0];
                ref = btrfs_item_ptr(leaf, path->slots[0],
                                     struct btrfs_root_ref);
-
-               WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
-               WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
                ptr = (unsigned long)(ref + 1);
-               WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
+               if ((btrfs_root_ref_dirid(leaf, ref) != dirid) ||
+                   (btrfs_root_ref_name_len(leaf, ref) != name_len) ||
+                   memcmp_extent_buffer(leaf, name, ptr, name_len)) {
+                       err = -ENOENT;
+                       goto out;
+               }
                *sequence = btrfs_root_ref_sequence(leaf, ref);
 
                ret = btrfs_del_item(trans, tree_root, path);