Ensure that there are no changes between the last check to
bdrv_get_dirty_count and the switch to the target.
There is already a bdrv_drained_end call, we only need to ensure
that bdrv_drained_begin is not called twice.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
block/mirror.c | 35 +++++++++++++++++++++++------------
1 file changed, 23 insertions(+), 12 deletions(-)
diff --git a/block/mirror.c b/block/mirror.c
index 52f879a..3a0788e 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -622,6 +622,7 @@ static void coroutine_fn mirror_run(void *opaque)
MirrorExitData *data;
BlockDriverState *bs = blk_bs(s->common.blk);
BlockDriverState *target_bs = blk_bs(s->target);
+ bool need_drain = true;
int64_t length;
BlockDriverInfo bdi;
char backing_filename[2]; /* we only need 2 characters because we are only
@@ -757,11 +758,26 @@ static void coroutine_fn mirror_run(void *opaque)
* source has dirty data to copy!
*
* Note that I/O can be submitted by the guest while
- * mirror_populate runs.
+ * mirror_populate runs, so pause it now. Before deciding
+ * whether to switch to target check one last time if I/O has
+ * come in the meanwhile, and if not flush the data to disk.
*/
trace_mirror_before_drain(s, cnt);
- bdrv_co_drain(bs);
+
+ bdrv_drained_begin(bs);
cnt = bdrv_get_dirty_count(s->dirty_bitmap);
+ if (cnt > 0) {
+ bdrv_drained_end(bs);
+ continue;
+ }
+
+ /* The two disks are in sync. Exit and report successful
+ * completion.
+ */
+ assert(QLIST_EMPTY(&bs->tracked_requests));
+ s->common.cancelled = false;
+ need_drain = false;
+ break;
}
ret = 0;
@@ -774,13 +790,6 @@ static void coroutine_fn mirror_run(void *opaque)
} else if (!should_complete) {
delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0);
block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
- } else if (cnt == 0) {
- /* The two disks are in sync. Exit and report successful
- * completion.
- */
- assert(QLIST_EMPTY(&bs->tracked_requests));
- s->common.cancelled = false;
- break;
}
s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
}
@@ -792,6 +801,7 @@ immediate_exit:
* the target is a copy of the source.
*/
assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common)));
+ assert(need_drain);
mirror_wait_for_all_io(s);
}
@@ -804,9 +814,10 @@ immediate_exit:
data = g_malloc(sizeof(*data));
data->ret = ret;
- /* Before we switch to target in mirror_exit, make sure data doesn't
- * change. */
- bdrv_drained_begin(bs);
+
+ if (need_drain) {
+ bdrv_drained_begin(bs);
+ }
block_job_defer_to_main_loop(&s->common, mirror_exit, data);
}
--
2.7.4
