[Qemu-devel] [PATCH v2] block: mirror - use local_err to avoid NULL errp

[Qemu-devel] [PATCH v2] block: mirror - use local_err to avoid NULL errp

[Jeff Cody]

When starting a block job, commit_active_start() relies on whether *errp
is set by mirror_start_job.  This allows it to determine if the mirror
job start failed, so that it can clean up any changes to open flags from
the bdrv_reopen().  If errp is NULL, then it will not be able to
determine if mirror_start_job failed or not.

To avoid this, use a local Error variable, and then propagate the error
(if any) to errp.

Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 block/mirror.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index 2a43334..ddb5765 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -633,6 +633,8 @@ void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
 {
     int64_t length, base_length;
     int orig_base_flags;
+    Error *local_err = NULL;
+
 
     orig_base_flags = bdrv_get_flags(base);
 
@@ -663,9 +665,10 @@ void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
 
     bdrv_ref(base);
     mirror_start_job(bs, base, speed, 0, 0,
-                     on_error, on_error, cb, opaque, errp,
+                     on_error, on_error, cb, opaque, &local_err,
                      &commit_active_job_driver, false, base);
-    if (error_is_set(errp)) {
+    if (error_is_set(&local_err)) {
+        error_propagate(errp, local_err);
         goto error_restore_flags;
     }
 
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH v2] block: mirror - use local_err to avoid NULL errp

[Kevin Wolf]

Am 13.02.2014 um 15:23 hat Jeff Cody geschrieben:
> When starting a block job, commit_active_start() relies on whether *errp
> is set by mirror_start_job.  This allows it to determine if the mirror
> job start failed, so that it can clean up any changes to open flags from
> the bdrv_reopen().  If errp is NULL, then it will not be able to
> determine if mirror_start_job failed or not.
> 
> To avoid this, use a local Error variable, and then propagate the error
> (if any) to errp.
> 
> Reported-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Jeff Cody <jcody@redhat.com>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Re: [Qemu-devel] [PATCH v2] block: mirror - use local_err to avoid NULL errp

[Eric Blake]

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On 02/13/2014 07:23 AM, Jeff Cody wrote:
> When starting a block job, commit_active_start() relies on whether *errp
> is set by mirror_start_job.  This allows it to determine if the mirror
> job start failed, so that it can clean up any changes to open flags from
> the bdrv_reopen().  If errp is NULL, then it will not be able to
> determine if mirror_start_job failed or not.
> 
> To avoid this, use a local Error variable, and then propagate the error
> (if any) to errp.
> 
> Reported-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Jeff Cody <jcody@redhat.com>
> ---
>  block/mirror.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/block/mirror.c b/block/mirror.c
> index 2a43334..ddb5765 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -633,6 +633,8 @@ void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
>  {
>      int64_t length, base_length;
>      int orig_base_flags;
> +    Error *local_err = NULL;
> +
>  
>      orig_base_flags = bdrv_get_flags(base);

Why the double blank line?

Besides that,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v2] block: mirror - use local_err to avoid NULL errp

[Stefan Hajnoczi]

On Thu, Feb 13, 2014 at 09:23:38AM -0500, Jeff Cody wrote:
> When starting a block job, commit_active_start() relies on whether *errp
> is set by mirror_start_job.  This allows it to determine if the mirror
> job start failed, so that it can clean up any changes to open flags from
> the bdrv_reopen().  If errp is NULL, then it will not be able to
> determine if mirror_start_job failed or not.
> 
> To avoid this, use a local Error variable, and then propagate the error
> (if any) to errp.
> 
> Reported-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Jeff Cody <jcody@redhat.com>
> ---
>  block/mirror.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan