On Wed, 04/20 00:59, Max Reitz wrote:
> If the drive's dirty bitmap is dirtied while the mirror operation is
> running, the cache of the iterator used by the mirror code may become
> stale and not contain all dirty bits.
>
> This only becomes an issue if we are looking for contiguously dirty
> chunks on the drive. In that case, we can easily detect the discrepancy
> and just refresh the iterator if one occurs.
>
> Signed-off-by: Max Reitz <mre...@redhat.com>
> ---
> block/mirror.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/block/mirror.c b/block/mirror.c
> index 2714a77..9df1fae 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -334,6 +334,11 @@ static uint64_t coroutine_fn
> mirror_iteration(MirrorBlockJob *s)
> }
>
> hbitmap_next = hbitmap_iter_next(&s->hbi);
> + if (hbitmap_next > next_sector || hbitmap_next < 0) {
> + /* The bitmap iterator's cache is stale, refresh it */
> + bdrv_set_dirty_iter(&s->hbi, next_sector);
> + hbitmap_next = hbitmap_iter_next(&s->hbi);
> + }
> assert(hbitmap_next == next_sector);
> nb_chunks++;
> }
> --
> 2.8.0
>
Reviewed-by: Fam Zheng <f...@redhat.com>
