Re: [Qemu-devel] [PATCH v2 01/12] block: add error parameter to bdrv_snapshot_create() and related functions

[Eric Blake <eblake@redhat.com>]

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On 03/22/2013 07:16 AM, Pavel Hrdina wrote:
> Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
> ---
>  block.c                   | 22 ++++++++++++++++------
>  block/qcow2-snapshot.c    |  9 ++++++++-
>  block/qcow2.h             |  4 +++-
>  block/rbd.c               |  8 ++++++--
>  block/sheepdog.c          | 17 +++++++++--------
>  include/block/block.h     |  3 ++-
>  include/block/block_int.h |  3 ++-
>  qemu-img.c                |  2 +-
>  savevm.c                  |  2 +-
>  9 files changed, 48 insertions(+), 22 deletions(-)
> 

>  int bdrv_snapshot_create(BlockDriverState *bs,
> -                         QEMUSnapshotInfo *sn_info)
> +                         QEMUSnapshotInfo *sn_info,
> +                         Error **errp)
>  {
>      BlockDriver *drv = bs->drv;
> -    if (!drv)
> +
> +    if (!drv) {
> +        error_setg(errp, "Device '%s' has no medium.",

In general, error_setg() should not print a trailing '.' (only two
offenders to git grep 'error_setg.*\."').  I think we also tend to start
messages with lower case, although that's not as obvious (49 cases of
'error_setg[^"*"[A-Z]' vs. 121 of error_setg[^"]*"[a-z]').

> +
> +    error_setg(errp, "Snapshot is not supported for '%s'.",

And again, and probably throughout your series (although I'll quit
pointing it out).

> @@ -830,16 +832,18 @@ static int qemu_rbd_snap_create(BlockDriverState *bs,
>       */
>      if (sn_info->id_str[0] != '\0' &&
>          strcmp(sn_info->id_str, sn_info->name) != 0) {
> +        error_setg(errp, "ID and name have to be equal.");
>          return -EINVAL;
>      }
>  
>      if (strlen(sn_info->name) >= sizeof(sn_info->id_str)) {
> +        error_setg(errp, "Parameter 'name' has to be shorter that 127 chars.");

s/that/than/

>          return -ERANGE;
>      }
>  
>      r = rbd_snap_create(s->image, sn_info->name);
>      if (r < 0) {
> -        error_report("failed to create snap: %s", strerror(-r));
> +        error_setg(errp, "Failed to create snapshot: '%s'.", strerror(-r));

Use error_setg_errno(errp, -r, "failed to create snapshot").


> @@ -1779,9 +1781,8 @@ static int sd_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
>              s->name, sn_info->vm_state_size, s->is_snapshot);
>  
>      if (s->is_snapshot) {
> -        error_report("You can't create a snapshot of a snapshot VDI, "
> -                     "%s (%" PRIu32 ").", s->name, s->inode.vdi_id);
> -
> +        error_setg(errp, "You can't create a snapshot '%s' of a VDI snapshot.",
> +                   sn_info->name);

Why are you losing information from the previous version of this error
message?


>      if (ret < 0) {
> -        error_report("failed to create inode for snapshot. %s",
> -                     strerror(errno));
> +        error_setg(errp, "Failed to create inode for snapshot.");

Another case of losing information; error_setg_errno would be better
here, and anywhere else the old message included a strerror() call.

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


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