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authorMax Reitz <mreitz@redhat.com>2019-08-05 17:33:08 +0200
committerMax Reitz <mreitz@redhat.com>2019-08-06 13:17:25 +0200
commit9adc1cb49af8d4e54f57980b1eed5c0a4b2dafa6 (patch)
treee29390ef616214a461ab982c319dbce173e6a332 /block/mirror.c
parent8a9cb864086269af14bbd13f395472703cf99f8c (diff)
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mirror: Only mirror granularity-aligned chunks
In write-blocking mode, all writes to the top node directly go to the target. We must only mirror chunks of data that are aligned to the job's granularity, because that is how the dirty bitmap works. Therefore, the request alignment for writes must be the job's granularity (in write-blocking mode). Unfortunately, this forces all reads and writes to have the same granularity (we only need this alignment for writes to the target, not the source), but that is something to be fixed another time. Cc: qemu-stable@nongnu.org Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20190805153308.2657-1-mreitz@redhat.com Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Fixes: d06107ade0ce74dc39739bac80de84b51ec18546 Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block/mirror.c')
-rw-r--r--block/mirror.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/block/mirror.c b/block/mirror.c
index 8cb75fb..9f5c59e 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1481,6 +1481,15 @@ static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c,
*nshared = BLK_PERM_ALL;
}
+static void bdrv_mirror_top_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+ MirrorBDSOpaque *s = bs->opaque;
+
+ if (s && s->job && s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING) {
+ bs->bl.request_alignment = s->job->granularity;
+ }
+}
+
/* Dummy node that provides consistent read to its users without requiring it
* from its backing file and that allows writes on the backing file chain. */
static BlockDriver bdrv_mirror_top = {
@@ -1493,6 +1502,7 @@ static BlockDriver bdrv_mirror_top = {
.bdrv_co_block_status = bdrv_co_block_status_from_backing,
.bdrv_refresh_filename = bdrv_mirror_top_refresh_filename,
.bdrv_child_perm = bdrv_mirror_top_child_perm,
+ .bdrv_refresh_limits = bdrv_mirror_top_refresh_limits,
};
static BlockJob *mirror_start_job(
@@ -1637,6 +1647,25 @@ static BlockJob *mirror_start_job(
s->should_complete = true;
}
+ /*
+ * Must be called before we start tracking writes, but after
+ *
+ * ((MirrorBlockJob *)
+ * ((MirrorBDSOpaque *)
+ * mirror_top_bs->opaque
+ * )->job
+ * )->copy_mode
+ *
+ * has the correct value.
+ * (We start tracking writes as of the following
+ * bdrv_create_dirty_bitmap() call.)
+ */
+ bdrv_refresh_limits(mirror_top_bs, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ goto fail;
+ }
+
s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
if (!s->dirty_bitmap) {
goto fail;