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[Qemu-devel] [PULL 1/1] block: mirror - fix full sync mode when target d
From: |
Jeff Cody |
Subject: |
[Qemu-devel] [PULL 1/1] block: mirror - fix full sync mode when target does not support zero init |
Date: |
Thu, 1 Oct 2015 15:05:28 -0400 |
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 <address@hidden>
Message-id: address@hidden
Signed-off-by: Jeff Cody <address@hidden>
---
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