[pve-devel] [PATCH storage 2/2] plugins: allow limiting the number of protected backups per guest

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

The ability to mark backups as protected broke the implicit assumption
in vzdump that remove=1 and current number of backups being the limit
(i.e. sum of all keep options) will result in a backup being removed.

Introduce a new storage property 'max-protected-backups' to limit the
number of protected backups per guest. Use 5 as a default value, as it
should cover most use cases, while still not having too big of a
potential overhead in many scenarios.

For external plugins that do not return the backup subtype in
list_volumes, all protected backups with the same ID will count
towards the limit.

An alternative would be to count the protected backups when pruning.
While that would avoid the need for a new property, it would break the
current semantics of protected backups being ignored for pruning. It
also would be less flexible, e.g. for PBS, it can make sense to have
both keep-all=1 and a limit for the number of protected snapshots on
the PVE side.

Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
---
 PVE/Storage.pm                 | 24 ++++++++++++++++++++++++
 PVE/Storage/BTRFSPlugin.pm     |  3 ++-
 PVE/Storage/CIFSPlugin.pm      |  1 +
 PVE/Storage/CephFSPlugin.pm    |  1 +
 PVE/Storage/DirPlugin.pm       |  1 +
 PVE/Storage/GlusterfsPlugin.pm |  1 +
 PVE/Storage/NFSPlugin.pm       |  1 +
 PVE/Storage/PBSPlugin.pm       |  1 +
 PVE/Storage/Plugin.pm          |  7 +++++++
 9 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/PVE/Storage.pm b/PVE/Storage.pm
index d64019f..0643fad 100755
--- a/PVE/Storage.pm
+++ b/PVE/Storage.pm
@@ -232,6 +232,30 @@ sub update_volume_attribute {
     my $scfg = storage_config($cfg, $storeid);
     my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
 
+    my ($vtype, undef, $vmid) = $plugin->parse_volname($volname);
+    my $max_protected_backups = $scfg->{'max-protected-backups'} // 5;
+
+    if (
+	$vtype eq 'backup'
+	&& $vmid
+	&& $attribute eq 'protected'
+	&& $value
+	&& !$plugin->get_volume_attribute($scfg, $storeid, $volname, 'protected')
+	&& $max_protected_backups > -1 # -1 is unlimited
+    ) {
+	my $backups = $plugin->list_volumes($storeid, $scfg, $vmid, ['backup']);
+	my ($backup_type) = map { $_->{subtype} } grep { $_->{volid} eq $volid } $backups->@*;
+
+	my $protected_count = grep {
+	    $_->{protected} && (!$backup_type || ($_->{subtype} && $_->{subtype} eq $backup_type))
+	} $backups->@*;
+
+	if ($max_protected_backups <= $protected_count) {
+	    die "The number of protected backups per guest is limited to $max_protected_backups ".
+		"on storage '$storeid'\n";
+	}
+    }
+
     return $plugin->update_volume_attribute($scfg, $storeid, $volname, $attribute, $value);
 }
 
diff --git a/PVE/Storage/BTRFSPlugin.pm b/PVE/Storage/BTRFSPlugin.pm
index c8caa41..7dac34b 100644
--- a/PVE/Storage/BTRFSPlugin.pm
+++ b/PVE/Storage/BTRFSPlugin.pm
@@ -67,7 +67,8 @@ sub options {
 	shared => { optional => 1 },
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
-	'prune-backups'=> { optional => 1 },
+	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	is_mountpoint => { optional => 1 },
diff --git a/PVE/Storage/CIFSPlugin.pm b/PVE/Storage/CIFSPlugin.pm
index a3f9ebe..ac36d14 100644
--- a/PVE/Storage/CIFSPlugin.pm
+++ b/PVE/Storage/CIFSPlugin.pm
@@ -134,6 +134,7 @@ sub options {
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	username => { optional => 1 },
diff --git a/PVE/Storage/CephFSPlugin.pm b/PVE/Storage/CephFSPlugin.pm
index f75c1b8..4976747 100644
--- a/PVE/Storage/CephFSPlugin.pm
+++ b/PVE/Storage/CephFSPlugin.pm
@@ -155,6 +155,7 @@ sub options {
 	maxfiles => { optional => 1 },
 	keyring => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	'fs-name' => { optional => 1 },
     };
 }
diff --git a/PVE/Storage/DirPlugin.pm b/PVE/Storage/DirPlugin.pm
index c60818b..1baad63 100644
--- a/PVE/Storage/DirPlugin.pm
+++ b/PVE/Storage/DirPlugin.pm
@@ -58,6 +58,7 @@ sub options {
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	mkdir => { optional => 1 },
diff --git a/PVE/Storage/GlusterfsPlugin.pm b/PVE/Storage/GlusterfsPlugin.pm
index d8d2b88..ad386d2 100644
--- a/PVE/Storage/GlusterfsPlugin.pm
+++ b/PVE/Storage/GlusterfsPlugin.pm
@@ -133,6 +133,7 @@ sub options {
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
 	mkdir => { optional => 1 },
diff --git a/PVE/Storage/NFSPlugin.pm b/PVE/Storage/NFSPlugin.pm
index 0400c93..5bd7313 100644
--- a/PVE/Storage/NFSPlugin.pm
+++ b/PVE/Storage/NFSPlugin.pm
@@ -85,6 +85,7 @@ sub options {
 	disable => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	options => { optional => 1 },
 	content => { optional => 1 },
 	format => { optional => 1 },
diff --git a/PVE/Storage/PBSPlugin.pm b/PVE/Storage/PBSPlugin.pm
index 4b3f349..687901f 100644
--- a/PVE/Storage/PBSPlugin.pm
+++ b/PVE/Storage/PBSPlugin.pm
@@ -73,6 +73,7 @@ sub options {
 	'master-pubkey' => { optional => 1 },
 	maxfiles => { optional => 1 },
 	'prune-backups' => { optional => 1 },
+	'max-protected-backups' => { optional => 1 },
 	fingerprint => { optional => 1 },
     };
 }
diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
index 0a6c619..bbe0af4 100644
--- a/PVE/Storage/Plugin.pm
+++ b/PVE/Storage/Plugin.pm
@@ -155,6 +155,13 @@ my $defaultData = {
 	    optional => 1,
 	},
 	'prune-backups' => get_standard_option('prune-backups'),
+	'max-protected-backups' => {
+	    description => "Maximal number of protected backups per guest. Use '-1' for unlimited.",
+	    type => 'integer',
+	    minimum => -1,
+	    optional => 1,
+	    default => 5,
+	},
 	shared => {
 	    description => "Mark storage as shared.",
 	    type => 'boolean',
-- 
2.30.2