Am 31.08.2012 08:26, schrieb Markus Armbruster:
> Luiz Capitulino <lcapitul...@redhat.com> writes:
>
>> On Wed, 15 Aug 2012 09:41:43 +0200
>> Pavel Hrdina <phrd...@redhat.com> wrote:
>>
>>> Signed-off-by: Pavel Hrdina <phrd...@redhat.com>
>>> ---
>>> block.c | 25 +++++++++++++++++--------
>>> block.h | 3 ++-
>>> block/qcow2-snapshot.c | 9 ++++++++-
>>> block/qcow2.h | 4 +++-
>>> block/rbd.c | 20 ++++++++++++++------
>>> block/sheepdog.c | 17 +++++++++--------
>>> block_int.h | 3 ++-
>>> qemu-img.c | 2 +-
>>> savevm.c | 2 +-
>>> 9 files changed, 57 insertions(+), 28 deletions(-)
>>>
>>> diff --git a/block.c b/block.c
>>> index 016858b..8bc49b7 100644
>>> --- a/block.c
>>> +++ b/block.c
>>> @@ -2661,16 +2661,25 @@ BlockDriverState *bdrv_snapshots(void)
>>> }
>>>
>>> int bdrv_snapshot_create(BlockDriverState *bs,
>>> - QEMUSnapshotInfo *sn_info)
>>> + QEMUSnapshotInfo *sn_info,
>>> + Error **errp)
>>> {
>>> BlockDriver *drv = bs->drv;
>>> - if (!drv)
>>> - return -ENOMEDIUM;
>>> - if (drv->bdrv_snapshot_create)
>>> - return drv->bdrv_snapshot_create(bs, sn_info);
>>> - if (bs->file)
>>> - return bdrv_snapshot_create(bs->file, sn_info);
>>> - return -ENOTSUP;
>>> + int ret;
>>> +
>>> + if (!drv) {
>>> + error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM,
>>> bdrv_get_device_name(bs));
>>
>> We should only use QERR_ macros for the errors listed in the ErrorClass enum
>> (except GenericError), all other errors should generally use error_setg(),
>> like
>> this:
>>
>> error_setg(errp, "device '%s' has no medium);
>>
>>> + ret = -ENOMEDIUM;
>>
>> And, usually, we should get rid of errno propagation. There are two cases
>> here:
>
> The block layer consistently[*] uses -errno return values. Its
> consistency is valuable, and I'm a bit reluctant to break it. Maybe a
> new rule "returns -errno, except when it has an Error ** argument" could
> work. I'd like to hear Kevin's advice on this.
I'd rather not remove existing -errno returns if there's not good reason
why we can't provide them (or can't do so easily at least).
Kevin
