Re: [Qemu-devel] [RFC PATCH 02/16] block: Set dirty before doing write

From: Eric Blake <eblake@redhat.com>
To: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
	qemu-block@nongnu.org, Markus Armbruster <armbru@redhat.com>,
	mreitz@redhat.com, vsementsov@parallels.com,
	Stefan Hajnoczi <stefanha@redhat.com>,
	jsnow@redhat.com
Subject: Re: [Qemu-devel] [RFC PATCH 02/16] block: Set dirty before doing write
Date: Tue, 26 Jan 2016 10:52:51 -0700	[thread overview]
Message-ID: <56A7B273.4030208@redhat.com> (raw)
In-Reply-To: <1453804705-7205-3-git-send-email-famz@redhat.com>

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On 01/26/2016 03:38 AM, Fam Zheng wrote:
> So that driver can write the dirty bits into persistent dirty bitmaps in
> the write callback.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block/io.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

> 
> diff --git a/block/io.c b/block/io.c
> index 343ff1f..b964e7e 100644
> --- a/block/io.c
> +++ b/block/io.c
> @@ -1164,6 +1164,8 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs,
>          }
>      }
>  
> +    bdrv_set_dirty(bs, sector_num, nb_sectors);
> +
>      if (ret < 0) {
>          /* Do nothing, write notifier decided to fail this request */

This sets the dirty bit even on failure, but I guess that doesn't hurt
(it's better to mark too much dirty than it is to not mark enough).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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