That doesn't seem good to stop handling io when guest is still running.
For example it leads to the following:
After bdrv_drain_all_begin(), during vm_shutdown() scsi_dma_writev()
calls blk_aio_pwritev(). As we are in drained section the request waits
in blk_wait_while_drained().
Next, during bdrv_close_all() bs is removed from blk, and blk drain
finishes. So, the request is resumed, and fails with -ENOMEDIUM.
Corresponding BLOCK_IO_ERROR event is sent and takes place in libvirt
log. That doesn't seem good.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
Hi all!
In our product (v5.2 based) we faced -ENOMEDIUM BLOCK_IO_ERROR events
during qemu termination (by SIGTERM). I don't have a reproducer for
master. Still the problem seems possible.
Ideas of how to reproduce it are welcome.
Also, I thought that issuing blk_ requests from SCSI is not possible
during drained section, and logic with blk_wait_while_drained() was
introduced for IDE.. Which code is responsible for not issuing SCSI
requests during drained sections? May be it is racy.. Or it may be our
downstream problem, I don't know :(
softmmu/runstate.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/softmmu/runstate.c b/softmmu/runstate.c
index 10d9b7365a..1966d773f3 100644
--- a/softmmu/runstate.c
+++ b/softmmu/runstate.c
@@ -797,21 +797,18 @@ void qemu_cleanup(void)
*/
blk_exp_close_all();
+ /* No more vcpu or device emulation activity beyond this point */
+ vm_shutdown();
+ replay_finish();
+
/*
* 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();
- replay_finish();
-
job_cancel_sync_all();
bdrv_close_all();