From: "Darrick J. Wong" Subject: Re: [PATCHSET v3.1 0/7] data integrity: Stabilize pages during writeback for various fses Date: Mon, 16 May 2011 11:49:27 -0700 Message-ID: <20110516184927.GM20579@tux1.beaverton.ibm.com> References: <20110509230318.19566.66202.stgit@elm3c44.beaverton.ibm.com> <20110510125124.GD4402@quack.suse.cz> <20110511181901.GK20579@tux1.beaverton.ibm.com> <20110512094255.GA4690@quack.suse.cz> Reply-To: djwong@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Theodore Tso , Alexander Viro , OGAWA Hirofumi , Jens Axboe , "Martin K. Petersen" , Jeff Layton , Dave Chinner , linux-kernel , Dave Hansen , Christoph Hellwig , linux-mm@kvack.org, Chris Mason , Joel Becker , linux-scsi , linux-fsdevel , linux-ext4@vger.kernel.org, Mingming Cao To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20110512094255.GA4690@quack.suse.cz> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org On Thu, May 12, 2011 at 11:42:55AM +0200, Jan Kara wrote: > On Wed 11-05-11 11:19:01, Darrick J. Wong wrote: > > On Tue, May 10, 2011 at 02:51:24PM +0200, Jan Kara wrote: > > > On Mon 09-05-11 16:03:18, Darrick J. Wong wrote: > > > > I am still chasing down what exactly is broken in ext3. data=writeback mode > > > > passes with no failures. data=ordered, however, does not pass; my current > > > > suspicion is that jbd is calling submit_bh on data buffers but doesn't call > > > > page_mkclean to kick the userspace programs off the page before writing it. > > > Yes, ext3 in data=ordered mode writes pages from > > > journal_commit_transaction() via submit_bh() without clearing page dirty > > > bits thus page_mkclean() is not called for these pages. Frankly, do you > > > really want to bother with adding support for ext2 and ext3? People can use > > > ext4 as a fs driver when they want to start using blk-integrity support. > > > Especially ext2 patch looks really painful and just from a quick look I can > > > see code e.g. in fs/ext2/namei.c which isn't handled by your patch yet. > > > > Yeah, I agree that ext2 is ugly and ext3/jbd might be more painful. Are there > > any other code that wants stable pages that's already running with ext3? In > > this months-long discussion I've heard that encryption and raid also like > > stable pages during writes. Have those users been broken this whole time, or > > have they been stabilizing pages themselves? > I believe part of them has been broken (e.g. raid) and part of them do > copy-out so they were OK. A future step might be to undo all these homegrown copy-outs? > > I suppose we can cross the "ext3 fails horribly on DIF" bridge when someone > > complains about it. Possibly we could try to steer them to btrfs. > Well, btrfs might be a bit too advantageous for production servers but > ext4 would be definitely viable for them. Are there any distros that are going straight from ext3 to btrfs? --D -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org