During mirror, if the target device does not support zero init, a
mirror may result in a corrupted image for sync="full" mode.
This is due to how the initial dirty bitmap is set up prior to copying
data - we did not mark sectors as dirty that are unallocated. This
means those unallocated sectors are skipped over on the target, and for
a device without zero init, invalid data may reside in those holes.
If both of the following conditions are true, then we will explicitly
mark all sectors as dirty:
1.) sync = "full"
2.) bdrv_has_zero_init(target) == false
If the target does support zero init, but a target image is passed in
with data already present (i.e. an "existing" image), it is assumed the
data present in the existing image is valid data for those sectors.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id:
91ed4bc5bda7e2b09eb508b07c83f4071fe0b3c9.
1443705220.git.jcody@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
if (!s->is_none_mode) {
/* First part, loop on the sectors and initialize the dirty bitmap. */
BlockDriverState *base = s->base;
+ bool mark_all_dirty = s->base == NULL && !bdrv_has_zero_init(s->target);
+
for (sector_num = 0; sector_num < end; ) {
/* Just to make sure we are not exceeding int limit. */
int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS,
}
assert(n > 0);
- if (ret == 1) {
+ if (ret == 1 || mark_all_dirty) {
bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n);
}
sector_num += n;