From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Kent Overstreet <kmo@daterainc.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
Hannes Reinecke <hare@suse.de>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: Fix a regression where MS_SNAP_STABLE (stable pages snapshotting) was ignored
Date: Fri, 20 Sep 2013 09:54:07 -0700 [thread overview]
Message-ID: <20130920165407.GA10392@birch.djwong.org> (raw)
In-Reply-To: <20130920082807.GW22421@suse.de>
On Fri, Sep 20, 2013 at 09:28:07AM +0100, Mel Gorman wrote:
> On Fri, Sep 20, 2013 at 09:06:37AM +0100, Mel Gorman wrote:
> > On Thu, Sep 19, 2013 at 08:06:02PM -0700, Darrick J. Wong wrote:
> > > The "force" parameter in __blk_queue_bounce was being ignored, which means that
> > > stable page snapshots are not always happening (on ext3). This of course
> > > leads to DIF disks reporting checksum errors, so fix this regression.
> > >
> > > The regression was introduced in commit 6bc454d1 (bounce: Refactor
> > > __blk_queue_bounce to not use bi_io_vec)
> > >
> > > Reported-by: Mel Gorman <mgorman@suse.de>
> > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> >
> > I have no means of testing it but it looks right and thanks for checking
> > DIF disks.
> >
> > Acked-by: Mel Gorman <mgorman@suse.de>
> >
>
> That said the two checks are now redundant. They could just be deleted
> and depend entirely on the following check within the loop
>
> if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
> continue;
>
> with an update to the comment explaining that the check is for pages
> below the bounce pfn or for bios that require stable writes
I'm under the impression that the point of the first looping-check is to avoid
the bio_clone_bioset() if we're not going to bounce anything. But I could be
wrong. Maybe Kent can shed some light on this?
--D
>
> --
> Mel Gorman
> SUSE Labs
next prev parent reply other threads:[~2013-09-20 16:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-20 3:06 [PATCH] mm: Fix a regression where MS_SNAP_STABLE (stable pages snapshotting) was ignored Darrick J. Wong
2013-09-20 3:28 ` Mike Snitzer
2013-09-20 8:06 ` Mel Gorman
2013-09-20 8:28 ` Mel Gorman
2013-09-20 16:54 ` Darrick J. Wong [this message]
2013-09-24 8:33 ` Mel Gorman
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