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Re: [Qemu-block] [PATCH v4 13/13] block/mirror: Block "device IO" during
From: |
Fam Zheng |
Subject: |
Re: [Qemu-block] [PATCH v4 13/13] block/mirror: Block "device IO" during mirror exit |
Date: |
Tue, 19 May 2015 16:48:16 +0000 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, 05/19 10:04, Paolo Bonzini wrote:
> On 19/05/2015 13:49, Fam Zheng wrote:
> > When block job mirror is finished, the source and target is synced. But
> > we call bdrv_swap() later in main loop bh. If the guest write before
> > that, target will not get the new data.
>
> 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?
Fam
>
> Paolo
>
> > Reported-by: Wen Congyang <address@hidden>
> > Signed-off-by: Fam Zheng <address@hidden>
> > ---
> > block/mirror.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/block/mirror.c b/block/mirror.c
> > index 58f391a..d96403b 100644
> > --- a/block/mirror.c
> > +++ b/block/mirror.c
> > @@ -320,6 +320,8 @@ static void mirror_drain(MirrorBlockJob *s)
> >
> > typedef struct {
> > int ret;
> > + /* Use to pause device IO during mirror exit */
> > + Error *blocker;
> > } MirrorExitData;
> >
> > static void mirror_exit(BlockJob *job, void *opaque)
> > @@ -328,6 +330,8 @@ static void mirror_exit(BlockJob *job, void *opaque)
> > MirrorExitData *data = opaque;
> > AioContext *replace_aio_context = NULL;
> >
> > + bdrv_op_unblock(s->common.bs, BLOCK_OP_TYPE_DEVICE_IO, data->blocker);
> > + error_free(data->blocker);
> > if (s->to_replace) {
> > replace_aio_context = bdrv_get_aio_context(s->to_replace);
> > aio_context_acquire(replace_aio_context);
> > @@ -563,8 +567,10 @@ immediate_exit:
> > bdrv_release_dirty_bitmap(bs, s->dirty_bitmap);
> > bdrv_iostatus_disable(s->target);
> >
> > - data = g_malloc(sizeof(*data));
> > + data = g_malloc0(sizeof(*data));
> > data->ret = ret;
> > + error_setg(&data->blocker, "mirror job exiting");
> > + bdrv_op_block(bs, BLOCK_OP_TYPE_DEVICE_IO, data->blocker);
> > block_job_defer_to_main_loop(&s->common, mirror_exit, data);
> > }
> >
> >
- [Qemu-block] [PATCH v4 07/13] nbd-server: Clear "can_read" when "device io" blocker is set, (continued)
- [Qemu-block] [PATCH v4 07/13] nbd-server: Clear "can_read" when "device io" blocker is set, Fam Zheng, 2015/05/18
- [Qemu-block] [PATCH v4 08/13] blockdev: Block device IO during internal snapshot transaction, Fam Zheng, 2015/05/18
- [Qemu-block] [PATCH v4 03/13] block-backend: Add blk_op_blocker_add_notifier, Fam Zheng, 2015/05/18
- [Qemu-block] [PATCH v4 09/13] blockdev: Block device IO during external snapshot transaction, Fam Zheng, 2015/05/18
- [Qemu-block] [PATCH v4 06/13] virtio-scsi-dataplane: Add "device IO" op blocker listener, Fam Zheng, 2015/05/18
- [Qemu-block] [PATCH v4 12/13] block: Block "device IO" during bdrv_drain and bdrv_drain_all, Fam Zheng, 2015/05/18
- [Qemu-block] [PATCH v4 01/13] block: Add op blocker type "device IO", Fam Zheng, 2015/05/18
- [Qemu-block] [PATCH v4 11/13] blockdev: Block device IO during blockdev-backup transaction, Fam Zheng, 2015/05/18
- [Qemu-block] [PATCH v4 13/13] block/mirror: Block "device IO" during mirror exit, Fam Zheng, 2015/05/18
[Qemu-block] [PATCH v4 10/13] blockdev: Block device IO during drive-backup transaction, Fam Zheng, 2015/05/18