From: Christoph Hellwig <hch@infradead.org>
To: Jens Axboe <jaxboe@fusionio.com>
Cc: Christoph Hellwig <hch@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: merging discard request in the block layer
Date: Tue, 22 Mar 2011 17:00:34 -0400 [thread overview]
Message-ID: <20110322210034.GA9349@infradead.org> (raw)
In-Reply-To: <4D88FE5E.1010204@fusionio.com>
On Tue, Mar 22, 2011 at 08:54:06PM +0100, Jens Axboe wrote:
> > Index: xfs/block/blk-merge.c
> > ===================================================================
> > --- xfs.orig/block/blk-merge.c 2011-03-22 13:07:24.733857580 +0100
> > +++ xfs/block/blk-merge.c 2011-03-22 13:08:17.448856577 +0100
> > @@ -373,7 +373,7 @@ static int attempt_merge(struct request_
> > /*
> > * Don't merge file system requests and discard requests
> > */
> > - if ((req->cmd_flags & REQ_DISCARD) != (next->cmd_flags & REQ_DISCARD))
> > + if ((req->cmd_flags & REQ_DISCARD) || (next->cmd_flags & REQ_DISCARD))
> > return 0;
> >
> > /*
>
> That's not going to be enough, you want to disable the bio to request
> merging of discards as well in elevator.c:elv_rq_merge_ok(). Does
> that then fix it?
Applying the same fix in elv_rq_merge_ok seems to fix the issue, at
least the xfstests testcase that usually hits it is completes ok.
next prev parent reply other threads:[~2011-03-22 21:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-22 19:47 Christoph Hellwig
2011-03-22 19:54 ` Jens Axboe
2011-03-22 21:00 ` Christoph Hellwig [this message]
2011-03-22 21:03 ` Jens Axboe
2011-03-23 13:01 ` Christoph Hellwig
2011-03-23 15:26 ` Jens Axboe
2011-03-30 14:16 ` Christoph Hellwig
2011-05-03 18:05 ` Christoph Hellwig
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