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Re: [Qemu-block] [RFC PATCH 6/7] virtio-blk: Don't handle output when th
From: |
Fam Zheng |
Subject: |
Re: [Qemu-block] [RFC PATCH 6/7] virtio-blk: Don't handle output when there is "device IO" op blocker |
Date: |
Wed, 6 May 2015 20:20:23 +0800 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Wed, 05/06 14:07, Paolo Bonzini wrote:
>
>
> On 06/05/2015 13:23, Fam Zheng wrote:
> > virtio-blk now listens to op blocker change of the associated block
> > backend.
> >
> > Up on setting op blocker on BLOCK_OP_TYPE_DEVICE_IO:
> >
> > non-dataplane:
> > 1) Set VirtIOBlock.paused
> > 2) In virtio_blk_handle_output, do nothing if VirtIOBlock.paused
> >
> > dataplane:
> > 1) Clear the host event notifier
> > 2) In handle_notify, do nothing if VirtIOBlock.paused
> >
> > Up on removing the op blocker:
> >
> > non-dataplane:
> > 1) Clear VirtIOBlock.paused
> > 2) Schedule a BH on the AioContext of the backend, which calls
> > virtio_blk_handle_output, so that the previous unhandled kicks can
> > make progress
> >
> > dataplane:
> > 1) Set the host event notifier
> > 2) Notify the host event notifier so that unhandled events are
> > processed
> >
> > Signed-off-by: Fam Zheng <address@hidden>
>
> Does non-dataplane need to do anything, since it uses iohandlers rather
> than aio_set_event_notifier_handler?
I guess it's not for this specific bug. See this as an attempt on a general
purpose "pause" mechanism to the device in investment for the future, for
example, bdrv_aio_drain. ;-)
I can drop it in v2 if you think the idea is not very helpful.
Fam
- [Qemu-block] [RFC PATCH 1/7] block: Add op blocker type "device IO", (continued)
- [Qemu-block] [RFC PATCH 1/7] block: Add op blocker type "device IO", Fam Zheng, 2015/05/06
- [Qemu-block] [RFC PATCH 2/7] block: Block "device IO" during bdrv_drain and bdrv_drain_all, Fam Zheng, 2015/05/06
- [Qemu-block] [RFC PATCH 3/7] block: Add op blocker notifier list, Fam Zheng, 2015/05/06
- [Qemu-block] [RFC PATCH 4/7] block-backend: Add blk_op_blocker_add_notifier, Fam Zheng, 2015/05/06
- [Qemu-block] [RFC PATCH 5/7] virtio-blk: Move complete_request to 'ops' structure, Fam Zheng, 2015/05/06
- [Qemu-block] [RFC PATCH 7/7] blockdev: Add "device IO" op blocker during snapshot transaction, Fam Zheng, 2015/05/06
- [Qemu-block] [RFC PATCH 6/7] virtio-blk: Don't handle output when there is "device IO" op blocker, Fam Zheng, 2015/05/06
- Re: [Qemu-block] [RFC PATCH 0/7] Fix transactional snapshot with virtio-blk dataplane, Stefan Hajnoczi, 2015/05/07