From patchwork Mon Feb 24 15:45:32 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "J. Bruce Fields" X-Patchwork-Id: 323683 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 38DFA2C00CC for ; Tue, 25 Feb 2014 02:45:39 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752832AbaBXPpg (ORCPT ); Mon, 24 Feb 2014 10:45:36 -0500 Received: from fieldses.org ([174.143.236.118]:59228 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752446AbaBXPpf (ORCPT ); Mon, 24 Feb 2014 10:45:35 -0500 Received: from bfields by fieldses.org with local (Exim 4.76) (envelope-from ) id 1WHxim-0005K2-Dp; Mon, 24 Feb 2014 10:45:32 -0500 Date: Mon, 24 Feb 2014 10:45:32 -0500 From: "J. Bruce Fields" To: Jan Kara Cc: Matthew Rahtz , linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org Subject: Re: warning in ext4_journal_start_sb on filesystem freeze Message-ID: <20140224154532.GB11992@fieldses.org> References: <217983071.143460.1385453196946.JavaMail.zimbra@rapitasystems.com> <1697998867.143517.1385454051031.JavaMail.zimbra@rapitasystems.com> <20131126125826.GA4503@quack.suse.cz> <622177618.727.1393062606061.JavaMail.zimbra@rapitasystems.com> <20140224095525.GA20532@quack.suse.cz> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20140224095525.GA20532@quack.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Mon, Feb 24, 2014 at 10:55:25AM +0100, Jan Kara wrote: > On Sat 22-02-14 09:50:06, Matthew Rahtz wrote: > > Thanks for your help Jan, > > > > A few months later, we've noticed the issue is actually still there. > > Using 3.11.0-17-generic on Ubuntu 12.04, we’re seeing this in the kernel > > logs: > > > > [29243.606215] WARNING: CPU: 0 PID: 1785 at > > /build/buildd/linux-lts-saucy-3.11.0/fs/ext4/ext4_jbd2.c:48 > > ext4_journal_check_start+0x83/0x90() > > > > Having a look at the Ubuntu source package for that version, it > > definitely does include commit 03d95eb2f2578083a3f6286262e1cb5d88a00c02, > > and the line generating the warning is still: > > > > WARN_ON(sb->s_writers.frozen == SB_FREEZE_COMPLETE); > > > > Are there any other obvious possibilities for what may be causing this? > > There seem to be some users of Oracle Linux experiencing similar problems > > at https://community.oracle.com/thread/2617418, which was apparently > > fixed in Oracle's kernel version '3.8.13-26.el6uek'. Any word on when > > this might be integrated into the official kernel? > > > > Full call trace included below. > Looking at the trace below, now the problem seems to be in the NFS server > code. NFS should get protection against the filesystem being frozen (or > remounted read-only for that matter) via mnt_want_write() before calling > into notify_change() (actually before calling fh_lock() because of lock > ordering). Similarly to what we do e.g. in fchownat(). Bruce? Like this? But I wonder why this is just popping up now--as far as I can tell we've had the bug since those write counts were introduced. --b. --- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 6d7be3f..d573b61 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -445,12 +445,16 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap, err = nfserr_notsync; goto out_put_write_access; } + host_err = fh_want_write(fhp); + if (host_err) + goto out_nfserr; fh_lock(fhp); host_err = notify_change(dentry, iap, NULL); fh_unlock(fhp); + fh_drop_write(fhp); +out_nfserr: err = nfserrno(host_err); - out_put_write_access: if (size_change) put_write_access(inode);