On 09.01.19 15:48, Kevin Wolf wrote: > Am 09.01.2019 um 15:27 hat Max Reitz geschrieben: >> On 09.01.19 15:21, Kevin Wolf wrote: >>> Am 09.01.2019 um 15:10 hat Max Reitz geschrieben: >>>> On 06.09.18 13:11, Daniel Henrique Barboza wrote: >>>>> changes in v2: >>>>> - removed the "RFC" marker; >>>>> - added a new patch (patch 2) that removes >>>>> bdrv_snapshot_delete_by_id_or_name from the code; >>>>> - made changes in patch 1 as suggested by Murilo; >>>>> - previous patch set link: >>>>> https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg04658.html >>>>> >>>>> >>>>> It is not uncommon to see bugs being opened by testers that attempt to >>>>> create VM snapshots using HMP. It turns out that "0" and "1" are quite >>>>> common snapshot names and they trigger a lot of bugs. I gave an example >>>>> in the commit message of patch 1, but to sum up here: QEMU treats the >>>>> input of savevm/loadvm/delvm sometimes as 'ID', sometimes as 'name'. It >>>>> is documented as such, but this can lead to strange situations. >>>>> >>>>> Given that it is strange for an API to consider a parameter to be 2 fields >>>>> at the same time, and inadvently treating them as one or the other, and >>>>> that removing the ID field is too drastic, my idea here is to keep the >>>>> ID field for internal control, but do not let the user set it. >>>>> >>>>> I guess there's room for discussion about considering this change an API >>>>> change or not. It doesn't affect users of HMP and it doesn't affect >>>>> Libvirt, >>>>> but simplifying the meaning of the parameters of savevm/loadvm/delvm. >>>> >>>> (Yes, very late reply, I'm sorry...) >>>> >>>> I do think it affects users of HMP, because right now you can delete >>>> snapshots with their ID, and after this series you cannot. >>> >>> Can there be snapshots that can't be identified by a snapshot name, but >>> only by their ID? >> >> I don't know, but what I meant is that if you have scripts to do all >> this, you might have to adjust them with this change. > > That's what the H in HMP means. > >>>> I think we had a short discussion about just disallowing numeric >>>> snapshot names. How bad would that be? >>> >>> It would be incompatible with existing images and result in a more >>> complex snapshot identifier resolution. Why would it be any better? >> >> It wouldn't be incompatible with existing images if we'd just disallow >> creating such snapshots. I don't see how the identifier resolution >> would be more complex. >> >> I don't know if it'd be better. I'd just find it simpler (for us, that >> is -- for users, I'm not sure). > > Identifier resolution A: > - Find a snapshot that has the given identifier as a name > - If no such snapshot exists, it is an error > > Identifier resolution B: > - If the identifier is a number, find a snapshot that has the given > identifier as its ID > - If the identifier is not a number, find a snapshot that has the given > identifier as a name > - If no such snapshot exists, it is an error
No, my idea was to keep the resolution the same as it is; just to forbid creating new snapshots with numeric names. This would prevent users from getting into the whole situation. Max
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