debian/patches/old/mirror-fix-zero-init.patch

   1 From patchwork Thu Oct  1 19:05:28 2015
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   3 MIME-Version: 1.0
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   5 Subject: [PULL,
   6  1/1] block: mirror - fix full sync mode when target does not support
   7  zero init
   8 From: Jeff Cody <jcody@redhat.com>
   9 X-Patchwork-Id: 525278
  10 Message-Id: <1443726328-29484-2-git-send-email-jcody@redhat.com>
  11 To: qemu-block@nongnu.org
  12 Cc: peter.maydell@linaro.org, jcody@redhat.com, qemu-devel@nongnu.org
  13 Date: Thu,  1 Oct 2015 15:05:28 -0400
  14
  15 During mirror, if the target device does not support zero init, a
  16 mirror may result in a corrupted image for sync="full" mode.
  17
  18 This is due to how the initial dirty bitmap is set up prior to copying
  19 data - we did not mark sectors as dirty that are unallocated.  This
  20 means those unallocated sectors are skipped over on the target, and for
  21 a device without zero init, invalid data may reside in those holes.
  22
  23 If both of the following conditions are true, then we will explicitly
  24 mark all sectors as dirty:
  25
  26     1.) sync = "full"
  27     2.) bdrv_has_zero_init(target) == false
  28
  29 If the target does support zero init, but a target image is passed in
  30 with data already present (i.e. an "existing" image), it is assumed the
  31 data present in the existing image is valid data for those sectors.
  32
  33 Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
  34 Message-id: 91ed4bc5bda7e2b09eb508b07c83f4071fe0b3c9.1443705220.git.jcody@redhat.com
  35 Signed-off-by: Jeff Cody <jcody@redhat.com>
  36 ---
  37  block/mirror.c | 4 +++-
  38  1 file changed, 3 insertions(+), 1 deletion(-)
  39
  40 diff --git a/block/mirror.c b/block/mirror.c
  41 index a258926..87928ab 100644
  42 --- a/block/mirror.c
  43 +++ b/block/mirror.c
  44 @@ -455,6 +455,8 @@ static void coroutine_fn mirror_run(void *opaque)
  45      if (!s->is_none_mode) {
  46          /* First part, loop on the sectors and initialize the dirty bitmap.  */
  47          BlockDriverState *base = s->base;
  48 +        bool mark_all_dirty = s->base == NULL && !bdrv_has_zero_init(s->target);
  49 +
  50          for (sector_num = 0; sector_num < end; ) {
  51              /* Just to make sure we are not exceeding int limit. */
  52              int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS,
  53 @@ -477,7 +479,7 @@ static void coroutine_fn mirror_run(void *opaque)
  54              }
  55
  56              assert(n > 0);
  57 -            if (ret == 1) {
  58 +            if (ret == 1 || mark_all_dirty) {
  59                  bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n);
  60              }
  61              sector_num += n;