From: Paolo Bonzini <pbonzini@redhat.com>
To: Fam Zheng <famz@redhat.com>
Cc: qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
Juan Quintela <quintela@redhat.com>,
qemu-devel@nongnu.org, mreitz@redhat.com,
Stefan Hajnoczi <stefanha@redhat.com>,
Amit Shah <amit.shah@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v4 13/13] block/mirror: Block "device IO" during mirror exit
Date: Tue, 19 May 2015 10:49:41 +0200 [thread overview]
Message-ID: <555AF925.6050809@redhat.com> (raw)
In-Reply-To: <20150519164816.GA5375@cpc-pc.redhat.com>
On 19/05/2015 18:48, Fam Zheng wrote:
>> >
>> > This is too late. As a rule, the blocker must be established before
>> > calling bdrv_drain, and removed on the next yield (in this case, before
>> > the assignment to last_pause_ns).
> I don't understand. If the blocker is removed before mirror_run returns,
> wouldn't more device IO already hit source image by the time mirror_exit runs?
If you go to mirror_exit, you won't reach the assignment (so you have to
remove the blocker in mirror_exit too).
But if you don't go to mirror_exit because cnt != 0, you must remove the
blocker before the next I/O.
Paolo
next prev parent reply other threads:[~2015-05-19 8:49 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-19 11:49 [Qemu-devel] [PATCH v4 00/13] Fix transactional snapshot with dataplane and NBD export Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 01/13] block: Add op blocker type "device IO" Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 02/13] block: Add op blocker notifier list Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 03/13] block-backend: Add blk_op_blocker_add_notifier Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 04/13] virtio-blk: Move complete_request to 'ops' structure Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 05/13] virtio-blk: Don't handle output when there is "device IO" op blocker Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 06/13] virtio-scsi-dataplane: Add "device IO" op blocker listener Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 07/13] nbd-server: Clear "can_read" when "device io" blocker is set Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 08/13] blockdev: Block device IO during internal snapshot transaction Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 09/13] blockdev: Block device IO during external " Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 10/13] blockdev: Block device IO during drive-backup transaction Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 11/13] blockdev: Block device IO during blockdev-backup transaction Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 12/13] block: Block "device IO" during bdrv_drain and bdrv_drain_all Fam Zheng
2015-05-19 11:49 ` [Qemu-devel] [PATCH v4 13/13] block/mirror: Block "device IO" during mirror exit Fam Zheng
2015-05-19 8:04 ` Paolo Bonzini
2015-05-19 16:48 ` Fam Zheng
2015-05-19 8:49 ` Paolo Bonzini [this message]
2015-05-19 18:37 ` Fam Zheng
2015-05-19 10:57 ` Paolo Bonzini
2015-05-20 2:23 ` Fam Zheng
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