[Qemu-devel] [PATCH for-2.5] call bdrv_drain_all() even if the vm is stopped

[Qemu-devel] [PATCH for-2.5] call bdrv_drain_all() even if the vm is stopped

[Wen Congyang]

There are still I/O operations when the vm is stopped. For example, stop the vm, and do block
migration. In this case, we don't drain all I/O operation, and may meet the following problem:
qemu-system-x86_64: migration/block.c:731: block_save_complete: Assertion `block_mig_state.submitted == 0' failed.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 cpus.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/cpus.c b/cpus.c
index 877bd70..43676fa 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1415,6 +1415,8 @@ int vm_stop_force_state(RunState state)
         return vm_stop(state);
     } else {
         runstate_set(state);
+
+        bdrv_drain_all();
         /* Make sure to return an error if the flush in a previous vm_stop()
          * failed. */
         return bdrv_flush_all();
-- 
2.5.0

Re: [Qemu-devel] [PATCH for-2.5] call bdrv_drain_all() even if the vm is stopped

[Paolo Bonzini]

On 20/11/2015 10:34, Wen Congyang wrote:
> There are still I/O operations when the vm is stopped. For example, stop the vm, and do block
> migration. In this case, we don't drain all I/O operation, and may meet the following problem:
> qemu-system-x86_64: migration/block.c:731: block_save_complete: Assertion `block_mig_state.submitted == 0' failed.
> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>  cpus.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/cpus.c b/cpus.c
> index 877bd70..43676fa 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -1415,6 +1415,8 @@ int vm_stop_force_state(RunState state)
>          return vm_stop(state);
>      } else {
>          runstate_set(state);
> +
> +        bdrv_drain_all();
>          /* Make sure to return an error if the flush in a previous vm_stop()
>           * failed. */
>          return bdrv_flush_all();
> 

Queued for 2.5-rc2, thanks!