Re: [pve-devel] [PATCH v2 storage] api: fix get content call for volumes

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

On March 7, 2023 9:31 am, Fiona Ebner wrote:
> Am 06.03.23 um 14:07 schrieb Christian Ebner:
>> `pvesh get /nodes/{node}/storage/{storage}/content/{volume}` failed for
>> several storage types, because the respective storage plugins returned
>> only the volumes `size` on `volume_size_info` calls, while also the format
>> is required.
>> 
>> This patch fixes the issue by returning also `format` and where possible `used`.
>> 
>> The issue was reported in the forum:
>> https://forum.proxmox.com/threads/pvesh-get-nodes-node-storage-storage-content-volume-returns-error.123747/
>> 
>> Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
>> ---
>> 
>> Changes since v1:
>>  * Remove errous check for $used being set, rely on fallback to 0 if undef
>>  * Return `parent` for RBD and ZFS
>>  * Return `used` for ZFS
>> 

[..]

>> diff --git a/PVE/Storage/ZFSPoolPlugin.pm b/PVE/Storage/ZFSPoolPlugin.pm
>> index 9fbd149..acc50d9 100644
>> --- a/PVE/Storage/ZFSPoolPlugin.pm
>> +++ b/PVE/Storage/ZFSPoolPlugin.pm
>> @@ -446,13 +446,17 @@ sub status {
>>  sub volume_size_info {
>>      my ($class, $scfg, $storeid, $volname, $timeout) = @_;
>>  
>> -    my (undef, $vname, undef, undef, undef, undef, $format) =
>> +    my (undef, $vname, undef, $parent, undef, undef, $format) =
>>          $class->parse_volname($volname);
>>  
>>      my $attr = $format eq 'subvol' ? 'refquota' : 'volsize';
>>      my $value = $class->zfs_get_properties($scfg, $attr, "$scfg->{pool}/$vname");
>> +    my $used = $class->zfs_get_properties($scfg, 'used', "$scfg->{pool}/$vname");
> 
> used also includes usage of snapshots and children. I think
> usedbydataset is better. Like that used <= size should be guaranteed.
> See man zfsprops for more information.
> 
> Also, one call to zfs_get_properties should be enough by passing both
> "$attr,used".
> 
> While you're at it, I'd also rename $value to $size then.

unfortunately not the case - a zvol can take up (significantly) more space than
volsize:

$ zpool get ashift testpool
NAME      PROPERTY  VALUE   SOURCE
testpool  ashift    12      local
$ zfs get volsize,volblocksize,space testpool/test
NAME           PROPERTY              VALUE          SOURCE
testpool/test  volsize               5G             local
testpool/test  volblocksize          8K             default
testpool/test  name                  testpool/test  -
testpool/test  available             11.2G          -
testpool/test  used                  7.43G          -
testpool/test  usedbysnapshots       0B             -
testpool/test  usedbydataset         7.32G          -
testpool/test  usedbyrefreservation  111M           -
testpool/test  usedbychildren        0B             -

this is the common "ashift=12 / volblocksize=8 / raidz2" pitfall..