Re: [PATCH 1/4] migration/savevm: respect qemu_fclose() error code in save_snapshot()

[Dr. David Alan Gilbert]

* Denis V. Lunev (d...@openvz.org) wrote:
> qemu_fclose() could return error, f.e. if bdrv_co_flush() will return
> the error.
> 
> This validation will become more important once we will start waiting of
> asynchronous IO operations, started from bdrv_write_vmstate(), which are
> coming soon.
> 
> Signed-off-by: Denis V. Lunev 
> CC: Kevin Wolf 
> CC: Max Reitz 
> CC: Stefan Hajnoczi 
> CC: Fam Zheng 
> CC: Juan Quintela 
> CC: "Dr. David Alan Gilbert" 
> CC: Vladimir Sementsov-Ogievskiy 
> CC: Denis Plotnikov 

We check the return value in very few other places; I think in the
migration case we do flushes and assume that if the flushes work we
were OK; then most of the closes happen on error paths or after points
we think we're done.

Reviewed-by: Dr. David Alan Gilbert 

> ---
>  migration/savevm.c | 8 ++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/savevm.c b/migration/savevm.c
> index c00a6807d9..0ff5bb40ed 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -2628,7 +2628,7 @@ int save_snapshot(const char *name, Error **errp)
>  {
>  BlockDriverState *bs, *bs1;
>  QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
> -int ret = -1;
> +int ret = -1, ret2;
>  QEMUFile *f;
>  int saved_vm_running;
>  uint64_t vm_state_size;
> @@ -2712,10 +2712,14 @@ int save_snapshot(const char *name, Error **errp)
>  }
>  ret = qemu_savevm_state(f, errp);
>  vm_state_size = qemu_ftell(f);
> -qemu_fclose(f);
> +ret2 = qemu_fclose(f);
>  if (ret < 0) {
>  goto the_end;
>  }
> +if (ret2 < 0) {
> +ret = ret2;
> +goto the_end;
> +}
>  
>  /* The bdrv_all_create_snapshot() call that follows acquires the 
> AioContext
>   * for itself.  BDRV_POLL_WHILE() does not support nested locking because
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK

Re: [PATCH 1/4] migration/savevm: respect qemu_fclose() error code in save_snapshot()

[Vladimir Sementsov-Ogievskiy]

11.06.2020 20:11, Denis V. Lunev wrote:

qemu_fclose() could return error, f.e. if bdrv_co_flush() will return
the error.

This validation will become more important once we will start waiting of
asynchronous IO operations, started from bdrv_write_vmstate(), which are
coming soon.

Signed-off-by: Denis V. Lunev
CC: Kevin Wolf
CC: Max Reitz
CC: Stefan Hajnoczi
CC: Fam Zheng
CC: Juan Quintela
CC: "Dr. David Alan Gilbert"
CC: Vladimir Sementsov-Ogievskiy
CC: Denis Plotnikov


Reviewed-by: Vladimir Sementsov-Ogievskiy 

--
Best regards,
Vladimir

[PATCH 1/4] migration/savevm: respect qemu_fclose() error code in save_snapshot()

[Denis V. Lunev]

qemu_fclose() could return error, f.e. if bdrv_co_flush() will return
the error.

This validation will become more important once we will start waiting of
asynchronous IO operations, started from bdrv_write_vmstate(), which are
coming soon.

Signed-off-by: Denis V. Lunev 
CC: Kevin Wolf 
CC: Max Reitz 
CC: Stefan Hajnoczi 
CC: Fam Zheng 
CC: Juan Quintela 
CC: "Dr. David Alan Gilbert" 
CC: Vladimir Sementsov-Ogievskiy 
CC: Denis Plotnikov 
---
 migration/savevm.c | 8 ++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index c00a6807d9..0ff5bb40ed 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2628,7 +2628,7 @@ int save_snapshot(const char *name, Error **errp)
 {
 BlockDriverState *bs, *bs1;
 QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
-int ret = -1;
+int ret = -1, ret2;
 QEMUFile *f;
 int saved_vm_running;
 uint64_t vm_state_size;
@@ -2712,10 +2712,14 @@ int save_snapshot(const char *name, Error **errp)
 }
 ret = qemu_savevm_state(f, errp);
 vm_state_size = qemu_ftell(f);
-qemu_fclose(f);
+ret2 = qemu_fclose(f);
 if (ret < 0) {
 goto the_end;
 }
+if (ret2 < 0) {
+ret = ret2;
+goto the_end;
+}
 
 /* The bdrv_all_create_snapshot() call that follows acquires the AioContext
  * for itself.  BDRV_POLL_WHILE() does not support nested locking because
-- 
2.17.1