From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46105) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhjAm-0000oV-1y for qemu-devel@nongnu.org; Thu, 01 Oct 2015 15:05:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZhjAk-0008GC-VE for qemu-devel@nongnu.org; Thu, 01 Oct 2015 15:05:43 -0400 From: Jeff Cody Date: Thu, 1 Oct 2015 15:05:28 -0400 Message-Id: <1443726328-29484-2-git-send-email-jcody@redhat.com> In-Reply-To: <1443726328-29484-1-git-send-email-jcody@redhat.com> References: <1443726328-29484-1-git-send-email-jcody@redhat.com> Subject: [Qemu-devel] [PULL 1/1] block: mirror - fix full sync mode when target does not support zero init List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: peter.maydell@linaro.org, jcody@redhat.com, qemu-devel@nongnu.org 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 Message-id: 91ed4bc5bda7e2b09eb508b07c83f4071fe0b3c9.1443705220.git.jcody@redhat.com Signed-off-by: Jeff Cody --- block/mirror.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block/mirror.c b/block/mirror.c index a258926..87928ab 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -455,6 +455,8 @@ static void coroutine_fn mirror_run(void *opaque) 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, @@ -477,7 +479,7 @@ static void coroutine_fn mirror_run(void *opaque) } 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; -- 1.9.3