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 <den@openvz.org>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Fam Zheng <fam@euphon.net>
CC: Juan Quintela <quintela@redhat.com>
CC: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
CC: Denis Plotnikov <dplotnikov@virtuozzo.com>
---
 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

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<den@openvz.org>
> CC: Kevin Wolf<kwolf@redhat.com>
> CC: Max Reitz<mreitz@redhat.com>
> CC: Stefan Hajnoczi<stefanha@redhat.com>
> CC: Fam Zheng<fam@euphon.net>
> CC: Juan Quintela<quintela@redhat.com>
> CC: "Dr. David Alan Gilbert"<dgilbert@redhat.com>
> CC: Vladimir Sementsov-Ogievskiy<vsementsov@virtuozzo.com>
> CC: Denis Plotnikov<dplotnikov@virtuozzo.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

-- 
Best regards,
Vladimir

* Denis V. Lunev (den@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 <den@openvz.org>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Max Reitz <mreitz@redhat.com>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Fam Zheng <fam@euphon.net>
> CC: Juan Quintela <quintela@redhat.com>
> CC: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> CC: Denis Plotnikov <dplotnikov@virtuozzo.com>

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 <dgilbert@redhat.com>

> ---
>  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 / dgilbert@redhat.com / Manchester, UK