From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail07.adl2.internode.on.net ([150.101.137.131]:25172 "EHLO ipmail07.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726894AbeK1Qkr (ORCPT ); Wed, 28 Nov 2018 11:40:47 -0500 Date: Wed, 28 Nov 2018 16:40:19 +1100 From: Dave Chinner To: "Darrick J. Wong" Cc: Allison Henderson , linux-block@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, martin.petersen@oracle.com, shirley.ma@oracle.com, bob.liu@oracle.com Subject: Re: [PATCH v1 6/7] xfs: Rewrite retried read Message-ID: <20181128054019.GN6311@dastard> References: <1543376991-5764-1-git-send-email-allison.henderson@oracle.com> <1543376991-5764-7-git-send-email-allison.henderson@oracle.com> <20181128051719.GK6311@dastard> <20181128052604.GE8125@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181128052604.GE8125@magnolia> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Nov 27, 2018 at 09:26:04PM -0800, Darrick J. Wong wrote: > On Wed, Nov 28, 2018 at 04:17:19PM +1100, Dave Chinner wrote: > > On Tue, Nov 27, 2018 at 08:49:50PM -0700, Allison Henderson wrote: > > > If we had to try more than one mirror to get a successful > > > read, then write that buffer back to correct the bad mirro > > > > > > Signed-off-by: Allison Henderson > > > --- > > > fs/xfs/xfs_buf.c | 8 ++++++++ > > > 1 file changed, 8 insertions(+) > > > > > > diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c > > > index f102d01..81f6491 100644 > > > --- a/fs/xfs/xfs_buf.c > > > +++ b/fs/xfs/xfs_buf.c > > > @@ -847,6 +847,14 @@ xfs_buf_read_map( > > > > > > } > > > retry_done: > > > + > > > + /* > > > + * if we had to try more than one mirror to sucessfully read > > > + * the buffer, write the buffer back > > > + */ > > > + if (!bp->b_error && i > 0) > > > + xfs_bwrite(bp); > > > + > > > > This can go in the case statement on retry and then you don't need > > to check for i > 0 or, well, bp->b_error. i.e. > > > > swtich (bp->b_error) { > > case -EBADCRC: > > case -EIO: > > case -EFSCORRUPTED: > > /* try again from different copy */ > > continue; > > 0: > > /* good copy, rewrite it to repair bad copy */ > > xfs_bwrite(bp); > > Some day we might want to provide some controls for how long we'll retry > these reads and whether or not we automatically rewrite buffers, since > some administrators might prefer fast fail to get failover started. Sure, but if the recovery code is trewn all through the read code, it becomes a mess to untangle. isolate the recovery code as much as possible, that way we can factor it out as it becomes more complex. > (Not now though) Which is exactly my point about future recovery complexity.... :P Cheers, Dave. -- Dave Chinner david@fromorbit.com