From: Paolo Bonzini <pbonzini@redhat.com>
To: John Snow <jsnow@redhat.com>, Kevin Wolf <kwolf@redhat.com>
Cc: qemu-block@nongnu.org, vsementsov@virtuozzo.com, famz@redhat.com,
jcody@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH v2 10/11] blockjob: refactor backup_start as backup_job_create
Date: Tue, 11 Oct 2016 10:56:28 +0200 [thread overview]
Message-ID: <c5f813d6-f2fb-87c2-a3c7-b884d5c393a8@redhat.com> (raw)
In-Reply-To: <a1c818de-5ba8-825e-b7e6-f25e98befa13@redhat.com>
On 11/10/2016 00:51, John Snow wrote:
>> Clearing the bitmap is a bug because the caller could expect that the
>> bitmap is in its original state if the transaction fails. I doubt this
>> is a problem in practice, but we should fix it anyway.
>
> We make a backup to undo the process if it fails. I only mention it to
> emphasize that the atomic point appears to be during prepare. In
> practice we hold the locks for the whole process, but... I think Paolo
> may be actively trying to change that.
Even now, atomicity must be ensured with bdrv_drained_begin/end. The
AioContext lock does not promise atomicity.
Paolo
next prev parent reply other threads:[~2016-10-11 8:56 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-30 22:00 [Qemu-devel] [PATCH v2 00/11] blockjobs: Fix transactional race condition John Snow
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 01/11] blockjob: fix dead pointer in txn list John Snow
2016-10-05 13:43 ` Kevin Wolf
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 02/11] blockjob: centralize QMP event emissions John Snow
2016-10-05 13:43 ` Kevin Wolf
2016-10-05 18:49 ` John Snow
2016-10-05 19:24 ` Eric Blake
2016-10-05 21:00 ` John Snow
2016-10-10 16:45 ` Kashyap Chamarthy
2016-10-10 18:36 ` John Snow
2016-10-10 19:28 ` Eric Blake
2016-10-11 13:32 ` Kashyap Chamarthy
2016-10-06 7:44 ` Kevin Wolf
2016-10-06 16:57 ` John Snow
2016-10-06 18:16 ` Eric Blake
2016-10-06 18:19 ` John Snow
2016-10-11 9:50 ` Markus Armbruster
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 03/11] Blockjobs: Internalize user_pause logic John Snow
2016-10-04 0:57 ` Jeff Cody
2016-10-04 2:46 ` John Snow
2016-10-04 18:35 ` John Snow
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 04/11] blockjobs: Always use block_job_get_aio_context John Snow
2016-10-05 14:02 ` Kevin Wolf
2016-10-06 20:22 ` John Snow
2016-10-07 7:49 ` Paolo Bonzini
2016-10-13 0:49 ` John Snow
2016-10-13 9:03 ` Paolo Bonzini
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 05/11] blockjobs: split interface into public/private John Snow
2016-10-05 14:17 ` Kevin Wolf
2016-10-05 16:20 ` John Snow
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 06/11] blockjobs: fix documentation John Snow
2016-10-05 15:03 ` Kevin Wolf
2016-10-05 16:22 ` John Snow
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 07/11] blockjob: add .clean property John Snow
2016-10-12 11:11 ` Vladimir Sementsov-Ogievskiy
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 08/11] blockjob: add .start field John Snow
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 09/11] blockjob: add block_job_start John Snow
2016-10-05 15:17 ` Kevin Wolf
2016-10-06 22:44 ` John Snow
2016-10-17 18:00 ` John Snow
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 10/11] blockjob: refactor backup_start as backup_job_create John Snow
2016-10-07 18:39 ` John Snow
2016-10-10 8:57 ` Kevin Wolf
2016-10-10 22:51 ` John Snow
2016-10-11 8:56 ` Paolo Bonzini [this message]
2016-10-11 9:35 ` Kevin Wolf
2016-10-17 8:59 ` Fam Zheng
2016-09-30 22:00 ` [Qemu-devel] [PATCH v2 11/11] iotests: add transactional failure race test John Snow
2016-10-12 11:26 ` Vladimir Sementsov-Ogievskiy
2016-10-12 16:09 ` John Snow
2016-09-30 22:22 ` [Qemu-devel] [PATCH v2 00/11] blockjobs: Fix transactional race condition no-reply
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