btrfs: record all roots for rename exchange on a subvol

commit 3e1740993e43116b3bc71b0aad1e6872f6ccf341 upstream.

Testing with the new fsstress support for subvolumes uncovered a pretty
bad problem with rename exchange on subvolumes.  We're modifying two
different subvolumes, but we only start the transaction on one of them,
so the other one is not added to the dirty root list.  This is caught by
btrfs_cow_block() with a warning because the root has not been updated,
however if we do not modify this root again we'll end up pointing at an
invalid root because the root item is never updated.

Fix this by making sure we add the destination root to the trans list,
the same as we do with normal renames.  This fixes the corruption.

Fixes: cdd1fedf8261 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC: stable@vger.kernel.org # 4.9+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2d23df72e091bc76ca7c555069ee5f4737ee3ec0..10a01dd0c4e6047514de868d95c8e17140cda942 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9554,6 +9554,9 @@ static int btrfs_rename_exchange(struct inode *old_dir,
                goto out_notrans;
        }
 
+       if (dest != root)
+               btrfs_record_root_in_trans(trans, dest);
+
        /*
         * We need to find a free sequence number both in the source and
         * in the destination directory for the exchange.