Re: [Qemu-devel] [PATCH 2/2] block: fix libvirt snapshot with existing bitmaps

[Eric Blake <eblake@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 1689 bytes --]

On 06/14/2016 11:08 AM, Vladimir Sementsov-Ogievskiy wrote:
> Fix the following bug:
> 
>  # virsh start test
>  Domain test started
> 
>  #  virsh qemu-monitor-command test \
>      '{"execute":"block-dirty-bitmap-add",\
>       "arguments":{"node":"drive0","name":"ab"}}'
>  {"return":{},"id":"libvirt-36"}'}'
> 
>  # virsh snapshot-create test
>  error: Unable to read from monitor: Connection reset by peer
> 
> Actually, assert "assert(pos < hb->size)" in hbitmap_iter_init fires,
> because qcow2_save_vmstate just writes to bs (not to bs->file->bs) after
> the end of the drive.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block/dirty-bitmap.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
> index 4902ca5..d28b49c 100644
> --- a/block/dirty-bitmap.c
> +++ b/block/dirty-bitmap.c
> @@ -364,6 +364,20 @@ void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
>                      int nr_sectors)
>  {
>      BdrvDirtyBitmap *bitmap;
> +    int64_t bitmap_size;
> +
> +    if (QLIST_EMPTY(&bs->dirty_bitmaps)) {
> +        return;
> +    }
> +
> +    bitmap_size = QLIST_FIRST(&bs->dirty_bitmaps)->size;
> +
> +    if (cur_sector >= bitmap_size) {
> +        /* this may come from qcow2_save_vmstate */
> +        return;
> +    }

Do we still need this patch after Kevin's work to fix vmstate to no
longer go through the block layer?

https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg02832.html

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


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 604 bytes --]