[PATCH 3.16 121/245] btrfs: do not delete mismatched root refs

Ben Hutchings
2020-04-23T23:16:45Z

From: Josef Bacik <josef@toxicpanda.com>

commit 423a716cd7be16fb08690760691befe3be97d3fc upstream.

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.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/root-tree.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -373,11 +373,13 @@ 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);