Re: [pve-devel] [PATCH storage 1/1] fix #3580: plugins: make preallocation mode selectable for qcow2 and raw images

[Fabian Ebner <f.ebner@proxmox.com>]

Am 09.09.21 um 13:11 schrieb Lorenz Stechauner:
> 
> On 09.09.21 12:25, Fabian Ebner wrote:
>> Am 08.09.21 um 10:11 schrieb alexandre derumier:
>>> Hi,
>>> it can be done too with ceph rbd with "rbd create ... –thick-provision"
>>>
>>
>> Hi,
>> there also is the 'sparse' storage config option (currently only used 
>> for ZFS plugins). If there is only thick or thin, re-using that one is 
>> probably nicer, because the newly proposed preallocation option seems 
>> to be closely tied to qemu-img.
> 
> Sounds like a good idea. I doubt, that anyone would use full 
> prellocation anyway, so simply using 'sparse' for prealloc=off and 
> default remains prealloc=metadata sounds good.
> 

I actually only meant re-using 'sparse' for the RBD use case. But yes, 
it seems like re-using it for the qemu-img use case would be enough to 
fix the bug too. It might be a bit confusing though, because when sparse 
is not set, the images would still be mostly sparse (except for metadata).

>>
>>> Le lundi 06 septembre 2021 à 15:15 +0200, Lorenz Stechauner a écrit :
>>>> the plugins for file based storages
>>>>   * BTRFS
>>>>   * CIFS
>>>>   * Dir
>>>>   * Glusterfs
>>>>   * NFS
>>>> now allow the option 'preallocation'.
>>>>
>>>> 'preallocation' can have four values:
>>>>   * default
>>>>   * off
>>>>   * metadata
>>>>   * falloc
>>>>   * full
>>>> see man pages for `qemu-img` for what these mean exactly. [0]
>>>>
>>>> the defualt value was chosen to be
>>>>   * qcow2: metadata (as previously)
>>>>   * raw: off (I was unable to find any documentation on this, so
>>>>      could only test this and found, that 'off' was the most
>>>>      fitting.)
>>>>
>>>> when using 'metadata' as preallocation mode, for raw images 'off'
>>>> is used.
>>>>
>>>> [0]
>>>> https://qemu.readthedocs.io/en/latest/system/images.html#disk-image-file-formats 
>>>>
>>>>
>>>> Signed-off-by: Lorenz Stechauner <l.stechauner@proxmox.com>
>>>> ---
>>>>   PVE/Storage/BTRFSPlugin.pm     |  1 +
>>>>   PVE/Storage/CIFSPlugin.pm      |  1 +
>>>>   PVE/Storage/DirPlugin.pm       |  1 +
>>>>   PVE/Storage/GlusterfsPlugin.pm |  4 ++-
>>>>   PVE/Storage/NFSPlugin.pm       |  1 +
>>>>   PVE/Storage/Plugin.pm          | 46
>>>> +++++++++++++++++++++++++++++++++-
>>>>   6 files changed, 52 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/PVE/Storage/BTRFSPlugin.pm b/PVE/Storage/BTRFSPlugin.pm
>>>> index fe42082..31a2954 100644
>>>> --- a/PVE/Storage/BTRFSPlugin.pm
>>>> +++ b/PVE/Storage/BTRFSPlugin.pm
>>>> @@ -73,6 +73,7 @@ sub options {
>>>>          is_mountpoint => { optional => 1 },
>>>>          nocow => { optional => 1 },
>>>>          mkdir => { optional => 1 },
>>>> +       preallocation => { optional => 1 },
>>>>          # TODO: The new variant of mkdir with  `populate` vs
>>>> `create`...
>>>>       };
>>>>   }
>>>> diff --git a/PVE/Storage/CIFSPlugin.pm b/PVE/Storage/CIFSPlugin.pm
>>>> index 0221069..2d94413 100644
>>>> --- a/PVE/Storage/CIFSPlugin.pm
>>>> +++ b/PVE/Storage/CIFSPlugin.pm
>>>> @@ -140,6 +140,7 @@ sub options {
>>>>          smbversion => { optional => 1},
>>>>          mkdir => { optional => 1 },
>>>>          bwlimit => { optional => 1 },
>>>> +       preallocation => { optional => 1 },
>>>>       };
>>>>   }
>>>>   diff --git a/PVE/Storage/DirPlugin.pm b/PVE/Storage/DirPlugin.pm
>>>> index 2267f11..3eeec98 100644
>>>> --- a/PVE/Storage/DirPlugin.pm
>>>> +++ b/PVE/Storage/DirPlugin.pm
>>>> @@ -59,6 +59,7 @@ sub options {
>>>>          mkdir => { optional => 1 },
>>>>          is_mountpoint => { optional => 1 },
>>>>          bwlimit => { optional => 1 },
>>>> +       preallocation => { optional => 1 },
>>>>      };
>>>>   }
>>>>   diff --git a/PVE/Storage/GlusterfsPlugin.pm
>>>> b/PVE/Storage/GlusterfsPlugin.pm
>>>> index ea4df82..d8d2b88 100644
>>>> --- a/PVE/Storage/GlusterfsPlugin.pm
>>>> +++ b/PVE/Storage/GlusterfsPlugin.pm
>>>> @@ -137,6 +137,7 @@ sub options {
>>>>          format => { optional => 1 },
>>>>          mkdir => { optional => 1 },
>>>>          bwlimit => { optional => 1 },
>>>> +       preallocation => { optional => 1 },
>>>>       };
>>>>   }
>>>>   @@ -260,7 +261,8 @@ sub alloc_image {
>>>>         my $cmd = ['/usr/bin/qemu-img', 'create'];
>>>>   -    push @$cmd, '-o', 'preallocation=metadata' if $fmt eq 'qcow2';
>>>> +    my $prealloc_opt =
>>>> PVE::Storage::Plugin::preallocation_cmd_option($scfg, $fmt);
>>>> +    push @$cmd, '-o', $prealloc_opt if defined($prealloc_opt);
>>>>         push @$cmd, '-f', $fmt, $volumepath, "${size}K";
>>>>   diff --git a/PVE/Storage/NFSPlugin.pm b/PVE/Storage/NFSPlugin.pm
>>>> index 39bf15a..21b288a 100644
>>>> --- a/PVE/Storage/NFSPlugin.pm
>>>> +++ b/PVE/Storage/NFSPlugin.pm
>>>> @@ -90,6 +90,7 @@ sub options {
>>>>          format => { optional => 1 },
>>>>          mkdir => { optional => 1 },
>>>>          bwlimit => { optional => 1 },
>>>> +       preallocation => { optional => 1 },
>>>>       };
>>>>   }
>>>>   diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
>>>> index b1865cb..4924525 100644
>>>> --- a/PVE/Storage/Plugin.pm
>>>> +++ b/PVE/Storage/Plugin.pm
>>>> @@ -41,6 +41,19 @@ our @SHARED_STORAGE = (
>>>>       'pbs',
>>>>   );
>>>>   +our $QCOW2_PREALLOCATION = {
>>>> +    off => 1,
>>>> +    metadata => 1,
>>>> +    falloc => 1,
>>>> +    full => 1,
>>>> +};
>>>> +
>>>> +our $RAW_PREALLOCATION = {
>>>> +    off => 1,
>>>> +    falloc => 1,
>>>> +    full => 1,
>>>> +};
>>>> +
>>>>   our $MAX_VOLUMES_PER_GUEST = 1024;
>>>>     cfs_register_file ('storage.cfg',
>>>> @@ -150,6 +163,11 @@ my $defaultData = {
>>>>              type => 'string', format => 'pve-storage-format',
>>>>              optional => 1,
>>>>          },
>>>> +       preallocation => {
>>>> +           description => "Preallocation mode for raw and qcow2
>>>> images.",
>>>> +           type => 'string', enum => ['default', 'off', 'metadata',
>>>> 'falloc', 'full'],
>>>> +           optional => 1,
>>>> +       },
>>>>       },
>>>>   };
>>>>   @@ -762,7 +780,8 @@ sub alloc_image {
>>>>       } else {
>>>>          my $cmd = ['/usr/bin/qemu-img', 'create'];
>>>>   -       push @$cmd, '-o', 'preallocation=metadata' if $fmt eq
>>>> 'qcow2';
>>>> +       my $prealloc_opt = preallocation_cmd_option($scfg, $fmt);
>>>> +       push @$cmd, '-o', $prealloc_opt if defined($prealloc_opt);
>>>>            push @$cmd, '-f', $fmt, $path, "${size}K";
>>>>   @@ -1484,4 +1503,29 @@ sub volume_import_formats {
>>>>       return ();
>>>>   }
>>>>   +sub preallocation_cmd_option {
>>>> +    my ($scfg, $fmt) = @_;
>>>> +
>>>> +    my $prealloc = $scfg->{preallocation};
>>>> +
>>>> +    $prealloc = undef if $prealloc eq 'default';
>>>> +
>>>> +    if ($fmt eq 'qcow2') {
>>>> +       $prealloc = $prealloc // 'metadata';
>>>> +
>>>> +       die "preallocation mode '$prealloc' not supported by format
>>>> '$fmt'\n" if !$QCOW2_PREALLOCATION->{$prealloc};
>>>> +
>>>> +       return "preallocation=$prealloc";
>>>> +    } elsif ($fmt eq 'raw') {
>>>> +       $prealloc = $prealloc // 'off';
>>>> +       $prealloc = 'off' if $prealloc eq 'metadata';
>>>> +
>>>> +       die "preallocation mode '$prealloc' not supported by format
>>>> '$fmt'\n" if !$RAW_PREALLOCATION->{$prealloc};
>>>> +
>>>> +       return "preallocation=$prealloc";
>>>> +    }
>>>> +
>>>> +    return undef;
>>>> +}
>>>> +
>>>>   1;
>>>
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