btrfs: fix fscrypt name leak after failure to join log transaction

When logging a new name, we don't expect to fail joining a log transaction
since we know at least one of the inodes was logged before in the current
transaction. However if we fail for some unexpected reason, we end up not
freeing the fscrypt name we previously allocated. So fix that by freeing
the name in case we failed to join a log transaction.

Fixes: ab3c5c18 ("btrfs: setup qstr from dentrys using fscrypt helper")
Reviewed-by: NSweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/tree-log.c

@@ -7459,8 +7459,11 @@ void btrfs_log_new_name(struct btrfs_trans_handle *trans,
 		 * not fail, but if it does, it's not serious, just bail out and
 		 * mark the log for a full commit.
 		 */
-		if (WARN_ON_ONCE(ret < 0))
+		if (WARN_ON_ONCE(ret < 0)) {
+			fscrypt_free_filename(&fname);
 			goto out;
+		}
+
 		log_pinned = true;
 
 		path = btrfs_alloc_path();