From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Jan Kara Subject: [ 21/37] jbd: Fix lock ordering bug in journal_unmap_buffer() Date: Fri, 30 Nov 2012 10:46:08 -0800 Message-Id: <20121130183859.533026283@linuxfoundation.org> In-Reply-To: <20121130183857.166228045@linuxfoundation.org> References: <20121130183857.166228045@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Kara commit 25389bb207987b5774182f763b9fb65ff08761c8 upstream. Commit 09e05d48 introduced a wait for transaction commit into journal_unmap_buffer() in the case we are truncating a buffer undergoing commit in the page stradding i_size on a filesystem with blocksize < pagesize. Sadly we forgot to drop buffer lock before waiting for transaction commit and thus deadlock is possible when kjournald wants to lock the buffer. Fix the problem by dropping the buffer lock before waiting for transaction commit. Since we are still holding page lock (and that is OK), buffer cannot disappear under us. Signed-off-by: Jan Kara Signed-off-by: Greg Kroah-Hartman --- fs/jbd/transaction.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/jbd/transaction.c +++ b/fs/jbd/transaction.c @@ -1955,7 +1955,9 @@ retry: spin_unlock(&journal->j_list_lock); jbd_unlock_bh_state(bh); spin_unlock(&journal->j_state_lock); + unlock_buffer(bh); log_wait_commit(journal, tid); + lock_buffer(bh); goto retry; } /*