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[Qemu-block] [PATCH 1/2] vl: Drain before (block) job cancel when quitti
From: |
Max Reitz |
Subject: |
[Qemu-block] [PATCH 1/2] vl: Drain before (block) job cancel when quitting |
Date: |
Thu, 13 Jun 2019 00:08:38 +0200 |
If the main loop cancels all block jobs while the block layer is not
drained, this cancelling may not happen instantaneously. We can start a
drained section before vm_shutdown(), which entails another
bdrv_drain_all(); this nested bdrv_drain_all() will thus be a no-op,
basically.
We do not have to end the drained section, because we actually do not
want any requests to happen from this point on.
Signed-off-by: Max Reitz <address@hidden>
---
I don't know whether it actually makes sense to never end this drained
section. It makes sense to me. Please correct me if I'm wrong.
---
vl.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/vl.c b/vl.c
index cd1fbc4cdc..3f8b3f74f5 100644
--- a/vl.c
+++ b/vl.c
@@ -4538,6 +4538,17 @@ int main(int argc, char **argv, char **envp)
*/
migration_shutdown();
+ /*
+ * We must cancel all block jobs while the block layer is drained,
+ * or cancelling will be affected by throttling and thus may block
+ * for an extended period of time.
+ * vm_shutdown() will bdrv_drain_all(), so we may as well include
+ * it in the drained section.
+ * We do not need to end this section, because we do not want any
+ * requests happening from here on anyway.
+ */
+ bdrv_drain_all_begin();
+
/* No more vcpu or device emulation activity beyond this point */
vm_shutdown();
--
2.21.0
[Qemu-block] [PATCH 2/2] iotests: Test quitting with job on throttled node, Max Reitz, 2019/06/12
Re: [Qemu-block] [PATCH 0/2] vl: Drain before (block) job cancel when quitting, Max Reitz, 2019/06/12