The mirror blockjob coroutine rate-limits itself by sleeping. The
coroutine also performs I/O asynchronously so it's important that the
aio callback doesn't wake the coroutine early as that breaks
rate-limiting.
Reported-by: Joaquim Barrera <jbarr...@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
block/mirror.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/block/mirror.c b/block/mirror.c
index adb09cf..0ef41f9 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -98,7 +98,14 @@ static void mirror_iteration_done(MirrorOp *op, int ret)
qemu_iovec_destroy(&op->qiov);
g_slice_free(MirrorOp, op);
- qemu_coroutine_enter(s->common.co, NULL);
+
+ /* Enter coroutine when it is not sleeping. The coroutine sleeps to
+ * rate-limit itself. The coroutine will eventually resume since there is
+ * a sleep timeout so don't wake it early.
+ */
+ if (s->common.busy) {
+ qemu_coroutine_enter(s->common.co, NULL);
+ }
}
static void mirror_write_complete(void *opaque, int ret)
--
1.8.5.3
