[pve-devel] [RFC storage 2/6] add generalized functions to manage volume attributes

Fabian Ebner f.ebner at proxmox.com
Fri Sep 24 13:05:58 CEST 2021


Am 24.09.21 um 10:54 schrieb Dominik Csapak:
> On 9/17/21 15:02, Fabian Ebner wrote:
>> replacing the ones for handling notes. The generic implementation in
>> Plugin.pm will fall back to the methods for notes to ensure backwards
>> compatibility with external plugins.
>>
>> This is mainly done to avoid the need to add new methods every time a
>> new attribute is added.
>>
>> Not adding a timeout parameter like the notes functions have, because
>> it was not used and can still be added if it ever is needed in the
>> future.
>>
>> For get_volume_attribute, undef will indicate that the attribute is
>> not supported. This makes it possible to distinguish "not supported"
>> from "error getting the attribute", which is useful when the attribute
>> is important for an operation. For example, free_image checking for
>> protection (introduced in a later patch) can abort if getting the
>> 'protected' attribute fails.
>>
>> Suggested-by: Thomas Lamprecht <t.lamprecht at proxmox.com>
>> Signed-off-by: Fabian Ebner <f.ebner at proxmox.com>
>> ---
>>
>> Hope I didn't miss a way this would break external plugins.
> 
> i think it would break a plugin that is not derived from
> the bas Plugin.pm no?
> 
> an example:
> 
> i have a CustomCIFSPlugin that uses CIFSPlugin as base
> 
> i have implemented a custom 'get_volume_notes' function
> 
> after this patch, 'get_volume_attribute' will be called, which
> falls back to the CIFSPlugin versionwhich calls the DirPlugin
> 'get_volume_attribute' instead of my custom 'get_volume_notes'
> 

Right. Having the fall-back only in Plugin.pm would not be enough then.

> since we did not document the custom plugins very well, i am
> not sure if that's even a supported scenario, or if a custom
> plugin always have to use the 'Plugin' as a base
> 
> if it is supported, we could only solve it by either make
> it a breaking api change, or by keeping the '*_volume_notes'
> around and fall back to *_volume_attribute implmentation
> 

That wouldn't solve the problem described above, would it? You still 
follow the same call-path and land in DirPlugin's get_volume_attribute 
in the end.

Yes, it would be necessary to keep the *_volume_notes functions around, 
but I think you need to have the opposite fall-back, i.e. 
*_volume_attribute has to call *_volume_notes to catch derived 
implementations like Plugin.pm.

> or did i make a mistake anywhere in my assumptions?
> 
>>
>> Requires an APIAGE+APIVER bump.
>>
>> The alternative to undef indicating "not supported" would be to add a
>> separate method like supports_volume_attribute. Or adapt
>> volume_has_feature, but it doesn't really feel like the right fit as
>> it's currently intended for features for guest images only.
>>
>>   PVE/API2/Storage/Content.pm |  7 +++---
>>   PVE/Storage.pm              | 12 +++++-----
>>   PVE/Storage/BTRFSPlugin.pm  |  4 ++--
>>   PVE/Storage/CIFSPlugin.pm   | 10 ++++----
>>   PVE/Storage/CephFSPlugin.pm | 10 ++++----
>>   PVE/Storage/DirPlugin.pm    | 47 +++++++++++++++++++++++--------------
>>   PVE/Storage/NFSPlugin.pm    | 10 ++++----
>>   PVE/Storage/PBSPlugin.pm    | 28 ++++++++++++++--------
>>   PVE/Storage/Plugin.pm       | 36 ++++++++++++++++++++++++++++
>>   9 files changed, 113 insertions(+), 51 deletions(-)
>>
>> diff --git a/PVE/API2/Storage/Content.pm b/PVE/API2/Storage/Content.pm
>> index 4d0ceb6..b3dc593 100644
>> --- a/PVE/API2/Storage/Content.pm
>> +++ b/PVE/API2/Storage/Content.pm
>> @@ -321,11 +321,12 @@ __PACKAGE__->register_method ({
>>           format => $format,
>>       };
>> -    # not all storages/types support notes, so ignore errors here
>> +    # keep going if fetching an optional attribute fails
>>       eval {
>> -        my $notes = PVE::Storage::get_volume_notes($cfg, $volid);
>> +        my $notes = PVE::Storage::get_volume_attribute($cfg, $volid, 
>> 'notes');
>>           $entry->{notes} = $notes if defined($notes);
>>       };
>> +    warn $@ if $@;
>>       return $entry;
>>       }});
>> @@ -371,7 +372,7 @@ __PACKAGE__->register_method ({
>>       PVE::Storage::check_volume_access($rpcenv, $authuser, $cfg, 
>> undef, $volid);
>>       if (exists $param->{notes}) {
>> -        PVE::Storage::update_volume_notes($cfg, $volid, 
>> $param->{notes});
>> +        PVE::Storage::update_volume_attribute($cfg, $volid, 'notes', 
>> $param->{notes});
>>       }
>>       return undef;
>> diff --git a/PVE/Storage.pm b/PVE/Storage.pm
>> index 7b319fe..729c90e 100755
>> --- a/PVE/Storage.pm
>> +++ b/PVE/Storage.pm
>> @@ -215,24 +215,24 @@ sub file_size_info {
>>       return PVE::Storage::Plugin::file_size_info($filename, $timeout);
>>   }
>> -sub get_volume_notes {
>> -    my ($cfg, $volid, $timeout) = @_;
>> +sub get_volume_attribute {
>> +    my ($cfg, $volid, $attribute) = @_;
>>       my ($storeid, $volname) = parse_volume_id($volid);
>>       my $scfg = storage_config($cfg, $storeid);
>>       my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
>> -    return $plugin->get_volume_notes($scfg, $storeid, $volname, 
>> $timeout);
>> +    return $plugin->get_volume_attribute($scfg, $storeid, $volname, 
>> $attribute);
>>   }
>> -sub update_volume_notes {
>> -    my ($cfg, $volid, $notes, $timeout) = @_;
>> +sub update_volume_attribute {
>> +    my ($cfg, $volid, $attribute, $value) = @_;
>>       my ($storeid, $volname) = parse_volume_id($volid);
>>       my $scfg = storage_config($cfg, $storeid);
>>       my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
>> -    $plugin->update_volume_notes($scfg, $storeid, $volname, $notes, 
>> $timeout);
>> +    return $plugin->update_volume_attribute($scfg, $storeid, 
>> $volname, $attribute, $value);
>>   }
>>   sub volume_size_info {
>> diff --git a/PVE/Storage/BTRFSPlugin.pm b/PVE/Storage/BTRFSPlugin.pm
>> index dbc1244..61bede2 100644
>> --- a/PVE/Storage/BTRFSPlugin.pm
>> +++ b/PVE/Storage/BTRFSPlugin.pm
>> @@ -136,9 +136,9 @@ sub status {
>>       return PVE::Storage::DirPlugin::status($class, $storeid, $scfg, 
>> $cache);
>>   }
>> -# TODO: sub get_volume_notes {}
>> +# TODO: sub get_volume_attribute {}
>> -# TODO: sub update_volume_notes {}
>> +# TODO: sub update_volume_attribute {}
>>   # croak would not include the caller from within this module
>>   sub __error {
>> diff --git a/PVE/Storage/CIFSPlugin.pm b/PVE/Storage/CIFSPlugin.pm
>> index c5f3894..bee6885 100644
>> --- a/PVE/Storage/CIFSPlugin.pm
>> +++ b/PVE/Storage/CIFSPlugin.pm
>> @@ -286,13 +286,15 @@ sub check_connection {
>>       return 1;
>>   }
>> -sub get_volume_notes {
>> +sub get_volume_attribute {
>>       my $class = shift;
>> -    PVE::Storage::DirPlugin::get_volume_notes($class, @_);
>> +
>> +    return PVE::Storage::DirPlugin::get_volume_attribute($class, @_);
>>   }
>> -sub update_volume_notes {
>> +sub update_volume_attribute {
>>       my $class = shift;
>> -    PVE::Storage::DirPlugin::update_volume_notes($class, @_);
>> +
>> +    return PVE::Storage::DirPlugin::update_volume_attribute($class, @_);
>>   }
>>   1;
>> diff --git a/PVE/Storage/CephFSPlugin.pm b/PVE/Storage/CephFSPlugin.pm
>> index 3b9a791..2c06804 100644
>> --- a/PVE/Storage/CephFSPlugin.pm
>> +++ b/PVE/Storage/CephFSPlugin.pm
>> @@ -232,14 +232,16 @@ sub deactivate_storage {
>>       }
>>   }
>> -sub get_volume_notes {
>> +sub get_volume_attribute {
>>       my $class = shift;
>> -    PVE::Storage::DirPlugin::get_volume_notes($class, @_);
>> +
>> +    return PVE::Storage::DirPlugin::get_volume_attribute($class, @_);
>>   }
>> -sub update_volume_notes {
>> +sub update_volume_attribute {
>>       my $class = shift;
>> -    PVE::Storage::DirPlugin::update_volume_notes($class, @_);
>> +
>> +    return PVE::Storage::DirPlugin::update_volume_attribute($class, @_);
>>   }
>>   1;
>> diff --git a/PVE/Storage/DirPlugin.pm b/PVE/Storage/DirPlugin.pm
>> index 0423e5f..6ab9ef2 100644
>> --- a/PVE/Storage/DirPlugin.pm
>> +++ b/PVE/Storage/DirPlugin.pm
>> @@ -87,32 +87,43 @@ sub parse_is_mountpoint {
>>       return $is_mp; # contains a path
>>   }
>> -sub get_volume_notes {
>> -    my ($class, $scfg, $storeid, $volname, $timeout) = @_;
>> +sub get_volume_attribute {
>> +    my ($class, $scfg, $storeid, $volname, $attribute) = @_;
>> -    my $path = $class->filesystem_path($scfg, $volname);
>> -    $path .= $class->SUPER::NOTES_EXT;
>> +    my ($vtype) = $class->parse_volname($volname);
>> +    return if $vtype ne 'backup';
>> -    return PVE::Tools::file_get_contents($path) if -f $path;
>> +    if ($attribute eq 'notes') {
>> +    my $path = $class->filesystem_path($scfg, $volname);
>> +    $path .= $class->SUPER::NOTES_EXT;
>> -    return '';
>> -}
>> +    return PVE::Tools::file_get_contents($path) if -f $path;
>> -sub update_volume_notes {
>> -    my ($class, $scfg, $storeid, $volname, $notes, $timeout) = @_;
>> +    return '';
>> +    }
>> -    my ($vtype) = $class->parse_volname($volname);
>> -    die "only backups can have notes\n" if $vtype ne 'backup';
>> +    return;
>> +}
>> -    my $path = $class->filesystem_path($scfg, $volname);
>> -    $path .= $class->SUPER::NOTES_EXT;
>> +sub update_volume_attribute {
>> +    my ($class, $scfg, $storeid, $volname, $attribute, $value) = @_;
>> -    if (defined($notes) && $notes ne '') {
>> -    PVE::Tools::file_set_contents($path, $notes);
>> -    } elsif (-e $path) {
>> -    unlink $path or die "could not delete notes - $!\n";
>> +    my ($vtype) = $class->parse_volname($volname);
>> +    die "only backups support attribute '$attribute'\n" if $vtype ne 
>> 'backup';
>> +
>> +    if ($attribute eq 'notes') {
>> +    my $path = $class->filesystem_path($scfg, $volname);
>> +    $path .= $class->SUPER::NOTES_EXT;
>> +
>> +    if (defined($value) && $value ne '') {
>> +        PVE::Tools::file_set_contents($path, $value);
>> +    } elsif (-e $path) {
>> +        unlink $path or die "could not delete notes - $!\n";
>> +    }
>> +    return;
>>       }
>> -    return;
>> +
>> +    die "attribute '$attribute' is not supported for storage type 
>> '$scfg->{type}'\n";
>>   }
>>   sub status {
>> diff --git a/PVE/Storage/NFSPlugin.pm b/PVE/Storage/NFSPlugin.pm
>> index 39bf15a..3a6efe5 100644
>> --- a/PVE/Storage/NFSPlugin.pm
>> +++ b/PVE/Storage/NFSPlugin.pm
>> @@ -188,13 +188,15 @@ sub check_connection {
>>       return 1;
>>   }
>> -sub get_volume_notes {
>> +sub get_volume_attribute {
>>       my $class = shift;
>> -    PVE::Storage::DirPlugin::get_volume_notes($class, @_);
>> +
>> +    return PVE::Storage::DirPlugin::get_volume_attribute($class, @_);
>>   }
>> -sub update_volume_notes {
>> +sub update_volume_attribute {
>>       my $class = shift;
>> -    PVE::Storage::DirPlugin::update_volume_notes($class, @_);
>> +
>> +    return PVE::Storage::DirPlugin::update_volume_attribute($class, @_);
>>   }
>>   1;
>> diff --git a/PVE/Storage/PBSPlugin.pm b/PVE/Storage/PBSPlugin.pm
>> index bb1c382..d8e1ac8 100644
>> --- a/PVE/Storage/PBSPlugin.pm
>> +++ b/PVE/Storage/PBSPlugin.pm
>> @@ -782,24 +782,32 @@ sub deactivate_volume {
>>       return 1;
>>   }
>> -sub get_volume_notes {
>> -    my ($class, $scfg, $storeid, $volname, $timeout) = @_;
>> +sub get_volume_attribute {
>> +    my ($class, $scfg, $storeid, $volname, $attribute) = @_;
>> +
>> +    if ($attribute eq 'notes') {
>> +    my (undef, $name,  undef, undef, undef, undef, $format) = 
>> $class->parse_volname($volname);
>> -    my (undef, $name,  undef, undef, undef, undef, $format) = 
>> $class->parse_volname($volname);
>> +    my $data = run_client_cmd($scfg, $storeid, "snapshot", [ "notes", 
>> "show", $name ]);
>> -    my $data = run_client_cmd($scfg, $storeid, "snapshot", [ "notes", 
>> "show", $name ]);
>> +    return $data->{notes} // '';
>> +    }
>> -    return $data->{notes};
>> +    return;
>>   }
>> -sub update_volume_notes {
>> -    my ($class, $scfg, $storeid, $volname, $notes, $timeout) = @_;
>> +sub update_volume_attribute {
>> +    my ($class, $scfg, $storeid, $volname, $attribute, $value) = @_;
>> -    my (undef, $name,  undef, undef, undef, undef, $format) = 
>> $class->parse_volname($volname);
>> +    if ($attribute eq 'notes') {
>> +    my (undef, $name,  undef, undef, undef, undef, $format) = 
>> $class->parse_volname($volname);
>> -    run_client_cmd($scfg, $storeid, "snapshot", [ "notes", "update", 
>> $name, $notes ], 1);
>> +    run_client_cmd($scfg, $storeid, "snapshot", [ "notes", "update", 
>> $name, $value ], 1);
>> -    return undef;
>> +    return;
>> +    }
>> +
>> +    die "attribute '$attribute' is not supported for storage type 
>> '$scfg->{type}'\n";
>>   }
>>   sub volume_size_info {
>> diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
>> index 417d1fd..1182008 100644
>> --- a/PVE/Storage/Plugin.pm
>> +++ b/PVE/Storage/Plugin.pm
>> @@ -851,18 +851,52 @@ sub file_size_info {
>>       return wantarray ? ($size, $format, $used, $parent, $st->ctime) 
>> : $size;
>>   }
>> +# FIXME remove on the next APIAGE reset.
>> +# Deprecated, use get_volume_attribute instead.
>>   sub get_volume_notes {
>>       my ($class, $scfg, $storeid, $volname, $timeout) = @_;
>>       die "volume notes are not supported for $class";
>>   }
>> +# FIXME remove on the next APIAGE reset.
>> +# Deprecated, use update_volume_attribute instead.
>>   sub update_volume_notes {
>>       my ($class, $scfg, $storeid, $volname, $notes, $timeout) = @_;
>>       die "volume notes are not supported for $class";
>>   }
>> +# Returns undef if the attribute is not supported for the volume.
>> +# Should die if there is an error fetching the attribute.
>> +# Possible attributes:
>> +# notes     - user-provided comments/notes.
>> +sub get_volume_attribute {
>> +    my ($class, $scfg, $storeid, $volname, $attribute) = @_;
>> +
>> +    if ($attribute eq 'notes') {
>> +     my $notes = eval { $class->get_volume_notes($scfg, $storeid, 
>> $volname); };
>> +     if (my $err = $@) {
>> +         return if $err =~ m/^volume notes are not supported/;
>> +         die $err;
>> +     }
>> +     return $notes;
>> +    }
>> +
>> +    return;
>> +}
>> +
>> +# Dies if the attribute is not supported for the volume.
>> +sub update_volume_attribute {
>> +    my ($class, $scfg, $storeid, $volname, $attribute, $value) = @_;
>> +
>> +    if ($attribute eq 'notes') {
>> +    $class->update_volume_notes($scfg, $storeid, $volname, $value);
>> +    }
>> +
>> +    die "attribute '$attribute' is not supported for storage type 
>> '$scfg->{type}'\n";
>> +}
>> +
>>   sub volume_size_info {
>>       my ($class, $scfg, $storeid, $volname, $timeout) = @_;
>>       my $path = $class->filesystem_path($scfg, $volname);
>> @@ -1098,6 +1132,8 @@ my $get_subdir_files = sub {
>>       return $res;
>>   };
>> +# If attributes are set on a volume, they should be included in the 
>> result.
>> +# See get_volume_attribute for a list of possible attributes.
>>   sub list_volumes {
>>       my ($class, $storeid, $scfg, $vmid, $content_types) = @_;
>>
> 
> 




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