Re: [Qemu-devel] [PATCH] block: bdrv_invalidate_cache: invalidate children first

[Stefan Hajnoczi <stefanha@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 1048 bytes --]

On Tue, Jan 31, 2017 at 02:23:08PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Current implementation invalidates firstly parent bds and then its
> children. This leads to the following bug:
> 
> after incoming migration, in bdrv_invalidate_cache_all:
> 1. invalidate parent bds - reopen it with BDRV_O_INACTIVE cleared
> 2. child is not yet invalidated
> 3. parent check that its BDRV_O_INACTIVE is cleared
> 4. parent writes to child
> 5. assert in bdrv_co_pwritev, as BDRV_O_INACTIVE is set for child
> 
> This patch fixes it by just changing invalidate sequence: invalidate
> children first.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
> 
> v2: I've missed that bdrv_invalidate_cache is already recursive, so we
> can change sequence here. Also v1 doesn't cover the case when
> bdrv_invalidate_cache is called not from bdrv_invalidate_cache_all.
> 
>  block.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 455 bytes --]