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From: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
To: Mikulas Patocka <mpatocka@redhat.com>,
	Alasdair G Kergon <agk@redhat.com>
Cc: device-mapper development <dm-devel@redhat.com>
Subject: Re: possible regression by the barrier patch in 2.6.30-rc2
Date: Mon, 20 Apr 2009 13:27:00 +0900	[thread overview]
Message-ID: <49EBF994.90801@ct.jp.nec.com> (raw)
In-Reply-To: <20090417132252.GA7843@agk.fab.redhat.com>

Hi Alasdair, Mikulas,

On 2009/04/17 22:22 +0900, Alasdair G Kergon wrote:
> On Fri, Apr 17, 2009 at 01:57:02PM +0900, Kiyoshi Ueda wrote:
>> 1. The semantics of flush suspend has been changed.
> 
> We absolutely must complete any I/O issued as a result of the lock_fs()
> call in dm_suspend().

I think that lock_fs() waits for I/O to complete, so no semantics change
in case of LOCKFS && FLUSH. (All I/O issued from lock_fs() are flushed.)

But in case of NO_LOCKFS && FLUSH, the semantics is changed:
  from: I/Os submitted before the suspend invocation are flushed
  to:   I/Os submitted even before the suspend invocation may not be flushed

I have no idea whether someone gets real damage by this semantics change.

> Alasdair

Thanks,
Kiyoshi Ueda

  reply	other threads:[~2009-04-20  4:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-17  4:57 possible regression by the barrier patch in 2.6.30-rc2 Kiyoshi Ueda
2009-04-17 13:22 ` Alasdair G Kergon
2009-04-20  4:27   ` Kiyoshi Ueda [this message]
2009-04-20  6:20     ` Mikulas Patocka
2009-10-28 15:21       ` Alasdair G Kergon
2009-11-05  1:53         ` Mikulas Patocka
2009-11-05  2:02           ` Mikulas Patocka
2009-11-06  2:42             ` snapshot of mirror (was: possible regression by the barrier patch in 2.6.30-rc2) Mikulas Patocka
2009-11-05  2:04           ` Re: possible regression by the barrier patch in 2.6.30-rc2 Alasdair G Kergon
2009-11-06  7:34         ` Kiyoshi Ueda

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