btrfs: abort unlink trans in missed error case

__btrfs_unlink_inode() aborts its transaction when it sees errors after
it removes the directory item.  But it missed the case where
btrfs_del_dir_entries_in_log() returns an error.  If this happens then
the unlink appears to fail but the items have been removed without
updating the directory size.  The directory then has leaked bytes in
i_size and can never be removed.

Adding the missing transaction abort at least makes this failure
consistent with the other failure cases.

I noticed this while reading the code after someone on irc reported
having a directory with i_size but no entries.  I tested it by forcing
btrfs_del_dir_entries_in_log() to return -ENOMEM.

Signed-off-by: Zach Brown <zab@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/inode.c

@@ -3616,6 +3616,8 @@ static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
 					   dir, index);
 	if (ret == -ENOENT)
 		ret = 0;
+	else if (ret)
+		btrfs_abort_transaction(trans, root, ret);
 err:
 	btrfs_free_path(path);
 	if (ret)