[pve-devel] [PATCH pve-storage 4/4] plugin: lvmplugin: add underlay functions

[Tiago Sousa via pve-devel <pve-devel@lists.proxmox.com>]

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From: Tiago Sousa <joao.sousa@eurotux.com>
To: pve-devel@lists.proxmox.com
Subject: [PATCH pve-storage 4/4] plugin: lvmplugin: add underlay functions
Date: Fri, 17 Oct 2025 12:25:29 +0100
Message-ID: <20251017112539.26471-5-joao.sousa@eurotux.com>

Signed-off-by: Tiago Sousa <joao.sousa@eurotux.com>
---
 src/PVE/Storage.pm           | 28 ++++++++++++++++
 src/PVE/Storage/LVMPlugin.pm | 65 +++++++++++++++++++++++++++++++-----
 src/PVE/Storage/Plugin.pm    | 29 +++++++++++++++-
 3 files changed, 113 insertions(+), 9 deletions(-)

diff --git a/src/PVE/Storage.pm b/src/PVE/Storage.pm
index ebbaf45..e0b4ba8 100755
--- a/src/PVE/Storage.pm
+++ b/src/PVE/Storage.pm
@@ -480,6 +480,34 @@ sub volume_resize {
     }
 }
 
+sub volume_underlay_size_info {
+    my ($cfg, $volid, $timeout) = @_;
+
+    my ($storeid, $volname) = parse_volume_id($volid, 1);
+    if ($storeid) {
+        my $scfg = storage_config($cfg, $storeid);
+        my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
+        return $plugin->volume_underlay_size_info($scfg, $storeid, $volname, $timeout);
+    } else {
+        return 0;
+    }
+}
+
+sub volume_underlay_resize {
+    my ($cfg, $volid, $size, $running, $backing_snap) = @_;
+
+    my ($storeid, $volname) = parse_volume_id($volid, 1);
+    if ($storeid) {
+        my $scfg = storage_config($cfg, $storeid);
+        my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
+        return $plugin->volume_underlay_resize($scfg, $storeid, $volname, $size, $running, $backing_snap);
+    } elsif ($volid =~ m|^(/.+)$| && -e $volid) {
+        die "resize file/device '$volid' is not possible\n";
+    } else {
+        die "unable to parse volume ID '$volid'\n";
+    }
+}
+
 sub volume_rollback_is_possible {
     my ($cfg, $volid, $snap, $blockers) = @_;
 
diff --git a/src/PVE/Storage/LVMPlugin.pm b/src/PVE/Storage/LVMPlugin.pm
index dc5e648..74366c3 100644
--- a/src/PVE/Storage/LVMPlugin.pm
+++ b/src/PVE/Storage/LVMPlugin.pm
@@ -400,6 +400,8 @@ sub options {
         tagged_only => { optional => 1 },
         bwlimit => { optional => 1 },
         'snapshot-as-volume-chain' => { optional => 1 },
+        chunksize => { optional => 1 },
+        'chunk-percentage' => { optional => 1 },
     };
 }
 
@@ -939,6 +941,44 @@ sub volume_resize {
     $lvmsize = "${lvmsize}k";
 
     my $path = $class->path($scfg, $volname);
+    lv_extend($class, $scfg, $storeid, $lvmsize, $path);
+
+    if (!$running && $format eq 'qcow2') {
+        my $preallocation = PVE::Storage::Plugin::preallocation_cmd_opt($scfg, $format);
+        PVE::Storage::Common::qemu_img_resize($path, $format, $size, $preallocation, 10);
+    }
+
+    return 1;
+}
+
+sub volume_underlay_resize {
+    my ($class, $scfg, $storeid, $volname, $backing_snap) = @_;
+
+    my ($format) = ($class->parse_volname($volname))[6];
+
+    my $path = $class->filesystem_path($scfg, $volname);
+    my $json = PVE::Storage::Common::qemu_img_info($path, undef, 10, 0);
+    my $json_decode = eval { decode_json($json) };
+    if ($@) {
+        die "Can't decode qemu snapshot list. Invalid JSON: $@\n";
+    }
+
+    my $virtual_size = $json_decode->{'virtual-size'} / 1024;
+
+    my $underlay_size = lv_size($path, 10);
+
+    my $updated_underlay_size = ($underlay_size + $scfg->{chunksize}) / 1024;
+    $updated_underlay_size = calculate_lvm_size($virtual_size, $format, $backing_snap)
+        if $updated_underlay_size >= $virtual_size;
+
+    my $lvmsize = "${updated_underlay_size}k";
+    lv_extend($class, $scfg, $storeid, $lvmsize, $path);
+
+    return $updated_underlay_size;
+}
+
+sub lv_extend {
+    my ($class, $scfg, $storeid, $lvmsize, $path) = @_;
     my $cmd = ['/sbin/lvextend', '-L', $lvmsize, $path];
 
     $class->cluster_lock_storage(
@@ -949,13 +989,6 @@ sub volume_resize {
             run_command($cmd, errmsg => "error resizing volume '$path'");
         },
     );
-
-    if (!$running && $format eq 'qcow2') {
-        my $preallocation = PVE::Storage::Plugin::preallocation_cmd_opt($scfg, $format);
-        PVE::Storage::Common::qemu_img_resize($path, $format, $size, $preallocation, 10);
-    }
-
-    return 1;
 }
 
 sub volume_size_info {
@@ -966,6 +999,22 @@ sub volume_size_info {
 
     return PVE::Storage::Plugin::file_size_info($path, $timeout, $format) if $format eq 'qcow2';
 
+    my $size = lv_size($path, $timeout);
+    return wantarray ? ($size, 'raw', 0, undef) : $size;
+}
+
+sub volume_underlay_size_info {
+    my ($class, $scfg, $storeid, $volname, $timeout) = @_;
+
+    my ($format) = ($class->parse_volname($volname))[6];
+    my $path = $class->filesystem_path($scfg, $volname);
+
+    return lv_size($path, $timeout);
+}
+
+sub lv_size {
+    my ($path, $timeout) = @_;
+
     my $cmd = [
         '/sbin/lvs',
         '--separator',
@@ -989,7 +1038,7 @@ sub volume_size_info {
             $size = int(shift);
         },
     );
-    return wantarray ? ($size, 'raw', 0, undef) : $size;
+    return $size;
 }
 
 sub volume_snapshot {
diff --git a/src/PVE/Storage/Plugin.pm b/src/PVE/Storage/Plugin.pm
index 8acd214..f08393b 100644
--- a/src/PVE/Storage/Plugin.pm
+++ b/src/PVE/Storage/Plugin.pm
@@ -228,6 +228,20 @@ my $defaultData = {
             default => 0,
             optional => 1,
         },
+        chunksize => {
+            type => 'integer',
+            description => 'The chunksize in Bytes to define the write threshold'
+                . 'of thin disks on thick storage.',
+            default => 1073741824, # 1 GiB
+            optional => 1,
+        },
+        'chunk-percentage' => {
+            type => 'number',
+            description => 'The percentage of written disk to define the write'
+                . 'threshold.',
+            default => 0.5,
+            optional => 1,
+        },
     },
 };
 
@@ -1265,7 +1279,6 @@ sub volume_size_info {
     my $format = ($class->parse_volname($volname))[6];
     my $path = $class->filesystem_path($scfg, $volname);
     return file_size_info($path, $timeout, $format);
-
 }
 
 sub volume_resize {
@@ -1285,6 +1298,20 @@ sub volume_resize {
     return undef;
 }
 
+sub volume_underlay_size_info {
+    my ($class, $scfg, $storeid, $volname, $timeout) = @_;
+
+    # Only supported by LVM for now
+    die "volume underlay is not supported for storage type '$scfg->{type}'\n";
+}
+
+sub volume_underlay_resize {
+    my ($class, $scfg, $storeid, $volname, $backing_snap) = @_;
+
+    # Only supported by LVM for now
+    die "volume underlay is not supported for storage type '$scfg->{type}'\n";
+}
+
 sub volume_snapshot {
     my ($class, $scfg, $storeid, $volname, $snap) = @_;
 
-- 
2.47.3



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