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From: Dave Chinner <david@fromorbit.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>,
	linux-kernel@vger.kernel.org, xfs@oss.sgi.com,
	Alasdair G Kergon <agk@redhat.com>,
	Andi Kleen <andi-suse@firstfloor.org>,
	Milan Broz <mbroz@redhat.com>
Subject: Re: Device loses barrier support (was: Fixed patch for simple barriers.)
Date: Sun, 7 Dec 2008 15:17:11 +1100	[thread overview]
Message-ID: <20081207041711.GA22525@disturbed> (raw)
In-Reply-To: <Pine.LNX.4.64.0812041139200.2434@hs20-bc2-1.build.redhat.com>

On Thu, Dec 04, 2008 at 11:45:44AM -0500, Mikulas Patocka wrote:
> > The write block with barrier bit varies, jbd/gfs2 do it synchronously
> > too and xfs does it asynchronously (with io done callbacks), but
> 
> And how does xfs preserve write ordering, if the barrier asynchronously 
> fails with -EOPNOTSUPP and there are other writes submitted after the 
> barrier?

Doesn't matter. XFS executes journal state changes during the I/O
completion callbacks a layer above this resubmit code. Hence,
if the I/O is resubmitted before the completion callbacks are
run, it just appears that the I/O has taken longer than expected
and the state change is delayed....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  parent reply	other threads:[~2008-12-07  4:17 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Pine.LNX.4.64.0812040009340.15169@hs20-bc2-1.build.redhat.com>
     [not found] ` <20081204100050.GN6703@one.firstfloor.org>
2008-12-04 14:00   ` Device loses barrier support (was: Fixed patch for simple barriers.) Mikulas Patocka
2008-12-04 14:20     ` Andi Kleen
2008-12-04 14:17       ` Mikulas Patocka
2008-12-04 14:58         ` Andi Kleen
2008-12-04 16:45           ` Mikulas Patocka
2008-12-04 17:48             ` Andi Kleen
2008-12-04 17:53               ` Christoph Hellwig
2008-12-04 19:37               ` Mikulas Patocka
2008-12-04 22:15                 ` Andi Kleen
2008-12-04 23:08                   ` Mikulas Patocka
2008-12-05  0:48                     ` Andi Kleen
2008-12-05  1:16                       ` Mikulas Patocka
2008-12-05  1:37                         ` Andi Kleen
2008-12-05  2:21                           ` Mikulas Patocka
2008-12-05  3:09                             ` Andi Kleen
2008-12-05 11:52                           ` Alan Cox
2008-12-05 12:29                             ` Andi Kleen
2008-12-05  3:26                 ` Device loses barrier support Eric Sandeen
2008-12-07  4:17             ` Dave Chinner [this message]
2008-12-05  5:44           ` Timothy Shimmin
     [not found] <bFnGM-7mA-5@gated-at.bofh.it>
     [not found] ` <bFpyX-1jh-15@gated-at.bofh.it>
     [not found]   ` <bFquY-2x2-5@gated-at.bofh.it>
     [not found]     ` <bFsnc-51o-37@gated-at.bofh.it>
     [not found]       ` <bFuyC-7Zt-11@gated-at.bofh.it>
     [not found]         ` <bFvuI-L8-29@gated-at.bofh.it>
     [not found]           ` <bFwTJ-2oc-13@gated-at.bofh.it>
     [not found]             ` <bFxwq-3g7-1@gated-at.bofh.it>
     [not found]               ` <bFxGa-3pz-1@gated-at.bofh.it>
     [not found]                 ` <bFHvW-7up-5@gated-at.bofh.it>
     [not found]                   ` <bFHPd-84I-13@gated-at.bofh.it>
2008-12-05 18:21                     ` Device loses barrier support (was: Fixed patch for simple barriers.) Bodo Eggert
2008-12-05 18:41                       ` Andi Kleen

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