mirror: finish earlier on error

Stop to produce new async copy requests from mirror_iteration if
critical error (error action = BLOCK_ERROR_ACTION_REPORT) detected.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/mirror.c

@@ -419,6 +419,10 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
             mirror_wait_for_io(s);
         }
 
+        if (s->ret < 0) {
+            return 0;
+        }
+
         mirror_clip_sectors(s, sector_num, &io_sectors);
         switch (mirror_method) {
         case MIRROR_METHOD_COPY: