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Date: Fri, 30 Oct 2015 12:01:59 -0400
From: Jeff Cody <jcody@redhat.com>
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Subject: Re: [Qemu-devel] [Qemu-block] [PATCH] blockdev: acquire AioContext
	in hmp_commit()
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To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, "Denis V. Lunev" <den@openvz.org>, qemu-devel@nongnu.org, qemu-block@nongnu.org, Markus Armbruster <armbru@redhat.com>

On Fri, Oct 30, 2015 at 03:57:41PM +0000, Stefan Hajnoczi wrote:
> This one slipped through.  Although we acquire AioContext when
> committing all devices we don't for just a single device.
> 
> AioContext must be acquired before calling bdrv_*() functions to
> synchronize access with other threads that may be using the AioContext.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  blockdev.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/blockdev.c b/blockdev.c
> index 18712d2..d611779 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1120,6 +1120,9 @@ void hmp_commit(Monitor *mon, const QDict *qdict)
>      if (!strcmp(device, "all")) {
>          ret = bdrv_commit_all();
>      } else {
> +        BlockDriverState *bs;
> +        AioContext *aio_context;
> +
>          blk = blk_by_name(device);
>          if (!blk) {
>              monitor_printf(mon, "Device '%s' not found\n", device);
> @@ -1129,7 +1132,14 @@ void hmp_commit(Monitor *mon, const QDict *qdict)
>              monitor_printf(mon, "Device '%s' has no medium\n", device);
>              return;
>          }
> -        ret = bdrv_commit(blk_bs(blk));
> +
> +        bs = blk_bs(blk);
> +        aio_context = bdrv_get_aio_context(bs);
> +        aio_context_acquire(aio_context);
> +
> +        ret = bdrv_commit(bs);
> +
> +        aio_context_release(aio_context);
>      }
>      if (ret < 0) {
>          monitor_printf(mon, "'commit' error for '%s': %s\n", device,
> -- 
> 2.4.3
> 
> 

Reviewed-by: Jeff Cody <jcody@redhat.com>