From: Jan Kara Subject: Re: [ext3] Changes to block device after an ext3 mount point has been remounted readonly Date: Wed, 24 Feb 2010 17:59:41 +0100 Message-ID: <20100224165940.GM3687@quack.suse.cz> References: <9F53CAF8-B6B4-40EB-89FA-CD6779D17DBE@sun.com> <20100222223252.GA13882@atrey.karlin.mff.cuni.cz> <20100222230552.GB13882@atrey.karlin.mff.cuni.cz> <16F918FB-F45D-478E-9358-550BB39E277E@sun.com> <20100223135531.GA7699@atrey.karlin.mff.cuni.cz> <877hq2tyg8.fsf@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "linux-fsdevel@vger.kernel.org" , ext4 development , Jan Kara To: Camille Moncelier Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Wed 24-02-10 17:26:37, Camille Moncelier wrote: > > Theoretically some pages may exist after rw=>ro remount > > because of generic race between write/sync, And they will be written > > in by writepage if page already has buffers. This not happen in ext4 > > because. Each time it try to perform writepages it try to start_journal > > and this result in EROFS. > > The race bug will be closed some day but new one may appear again. > > > > Let's be honest and change ext3 writepage like follows: > > - check ROFS flag inside write page > > - dump writepage's errors. > > > > > I think I don't understand correctly your patch. For me it seems that > when an ext3 filesystem is remounted ro, some data may not have been > written to disk right ? I think that Dmitry was concerned about the fact that a process could open a file and write to it after we synced the filesystem in do_remount_sb(). Honza -- Jan Kara SUSE Labs, CR