[pve-devel] [PATCH v3 pve-storage 2/3] lvmplugin: add qcow2 snapshot

[Alexandre Derumier via pve-devel <pve-devel@lists.proxmox.com>]

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From: Alexandre Derumier <alexandre.derumier@groupe-cyllene.com>
To: pve-devel@lists.proxmox.com
Subject: [PATCH v3 pve-storage 2/3] lvmplugin: add qcow2 snapshot
Date: Mon, 16 Dec 2024 10:12:19 +0100
Message-ID: <20241216091229.3142660-6-alexandre.derumier@groupe-cyllene.com>

Signed-off-by: Alexandre Derumier <alexandre.derumier@groupe-cyllene.com>
---
 src/PVE/Storage/LVMPlugin.pm | 231 ++++++++++++++++++++++++++++++++---
 1 file changed, 213 insertions(+), 18 deletions(-)

diff --git a/src/PVE/Storage/LVMPlugin.pm b/src/PVE/Storage/LVMPlugin.pm
index 88fd612..1257cd3 100644
--- a/src/PVE/Storage/LVMPlugin.pm
+++ b/src/PVE/Storage/LVMPlugin.pm
@@ -4,6 +4,7 @@ use strict;
 use warnings;
 
 use IO::File;
+use POSIX qw/ceil/;
 
 use PVE::Tools qw(run_command trim);
 use PVE::Storage::Plugin;
@@ -216,6 +217,7 @@ sub type {
 sub plugindata {
     return {
 	content => [ {images => 1, rootdir => 1}, { images => 1 }],
+	format => [ { raw => 1, qcow2 => 1 } , 'raw' ],
     };
 }
 
@@ -291,7 +293,10 @@ sub parse_volname {
     PVE::Storage::Plugin::parse_lvm_name($volname);
 
     if ($volname =~ m/^(vm-(\d+)-\S+)$/) {
-	return ('images', $1, $2, undef, undef, undef, 'raw');
+	my $name = $1;
+	my $vmid = $2;
+	my $format = $volname =~ m/\.qcow2$/ ? 'qcow2' : 'raw';
+	return ('images', $name, $vmid, undef, undef, undef, $format);
     }
 
     die "unable to parse lvm volume name '$volname'\n";
@@ -300,11 +305,13 @@ sub parse_volname {
 sub filesystem_path {
     my ($class, $scfg, $volname, $snapname) = @_;
 
-    die "lvm snapshot is not implemented"if defined($snapname);
+    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
+	$class->parse_volname($volname);
 
-    my ($vtype, $name, $vmid) = $class->parse_volname($volname);
+    die "snapshot is working with qcow2 format only" if defined($snapname) && $format ne 'qcow2';
 
     my $vg = $scfg->{vgname};
+    $name = $class->get_snap_volname($volname, $snapname) if $snapname;
 
     my $path = "/dev/$vg/$name";
 
@@ -332,7 +339,9 @@ sub find_free_diskname {
 
     my $disk_list = [ keys %{$lvs->{$vg}} ];
 
-    return PVE::Storage::Plugin::get_next_vm_diskname($disk_list, $storeid, $vmid, undef, $scfg);
+    $add_fmt_suffix = $fmt eq 'qcow2' ? 1 : undef;
+
+    return PVE::Storage::Plugin::get_next_vm_diskname($disk_list, $storeid, $vmid, $fmt, $scfg, $add_fmt_suffix);
 }
 
 sub lvcreate {
@@ -363,7 +372,15 @@ sub lvrename {
 sub alloc_image {
     my ($class, $storeid, $scfg, $vmid, $fmt, $name, $size) = @_;
 
-    die "unsupported format '$fmt'" if $fmt ne 'raw';
+    die "unsupported format '$fmt'" if $fmt !~ m/(raw|qcow2)/;
+
+    $name = $class->alloc_new_image($storeid, $scfg, $vmid, $fmt, $name, $size);
+    $class->format_qcow2($storeid, $scfg, $name, $size) if $fmt eq 'qcow2';
+    return $name;
+}
+
+sub alloc_new_image {
+    my ($class, $storeid, $scfg, $vmid, $fmt, $name, $size) = @_;
 
     die "illegal name '$name' - should be 'vm-$vmid-*'\n"
 	if  $name && $name !~ m/^vm-$vmid-/;
@@ -376,16 +393,45 @@ sub alloc_image {
 
     my $free = int($vgs->{$vg}->{free});
 
+
+    #add extra space for qcow2 metadatas
+    #without sub-allocated clusters : For 1TB storage : l2_size = disk_size × 8 / cluster_size
+    #with sub-allocated clusters : For 1TB storage : l2_size = disk_size × 8 / cluster_size / 16
+                                   #4MB overhead for 1TB with extented l2 clustersize=128k
+
+    my $qcow2_overhead = ceil($size/1024/1024/1024) * 4096;
+
+    my $lvmsize = $size;
+    $lvmsize += $qcow2_overhead if $fmt eq 'qcow2';
+
     die "not enough free space ($free < $size)\n" if $free < $size;
 
-    $name = $class->find_free_diskname($storeid, $scfg, $vmid)
+    $name = $class->find_free_diskname($storeid, $scfg, $vmid, $fmt)
 	if !$name;
 
-    lvcreate($vg, $name, $size, ["pve-vm-$vmid"]);
-
+    my $tags = ["pve-vm-$vmid"];
+    push @$tags, "\@pve-$name" if $fmt eq 'qcow2';
+    lvcreate($vg, $name, $lvmsize, $tags);
     return $name;
 }
 
+sub format_qcow2 {
+    my ($class, $storeid, $scfg, $name, $size, $backing_file) = @_;
+
+    # activate volume
+    $class->activate_volume($storeid, $scfg, $name, undef, {});
+    my $path = $class->path($scfg, $name, $storeid);
+    # create the qcow2 fs
+    my $cmd = ['/usr/bin/qemu-img', 'create'];
+    push @$cmd, '-b', $backing_file, '-F', 'qcow2' if $backing_file;
+    push @$cmd, '-f', 'qcow2', $path;
+    push @$cmd, "${size}K" if $size;
+    my $options = "extended_l2=on,";
+    $options .= PVE::Storage::Plugin::preallocation_cmd_option($scfg, 'qcow2');
+    push @$cmd, '-o', $options;
+    run_command($cmd);
+}
+
 sub free_image {
     my ($class, $storeid, $scfg, $volname, $isBase) = @_;
 
@@ -536,6 +582,12 @@ sub activate_volume {
 
     my $lvm_activate_mode = 'ey';
 
+    #activate volume && all snapshots volumes by tag
+    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
+	$class->parse_volname($volname);
+
+    $path = "\@pve-$name" if $format eq 'qcow2';
+
     my $cmd = ['/sbin/lvchange', "-a$lvm_activate_mode", $path];
     run_command($cmd, errmsg => "can't activate LV '$path'");
     $cmd = ['/sbin/lvchange', '--refresh', $path];
@@ -548,6 +600,10 @@ sub deactivate_volume {
     my $path = $class->path($scfg, $volname, $storeid, $snapname);
     return if ! -b $path;
 
+    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
+	$class->parse_volname($volname);
+    $path = "\@pve-$name" if $format eq 'qcow2';
+
     my $cmd = ['/sbin/lvchange', '-aln', $path];
     run_command($cmd, errmsg => "can't deactivate LV '$path'");
 }
@@ -555,15 +611,27 @@ sub deactivate_volume {
 sub volume_resize {
     my ($class, $scfg, $storeid, $volname, $size, $running) = @_;
 
-    $size = ($size/1024/1024) . "M";
+    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
+	$class->parse_volname($volname);
+
+    my $lvmsize = $size / 1024;
+    my $qcow2_overhead = ceil($size/1024/1024/1024/1024) * 4096;
+    $lvmsize += $qcow2_overhead if $format eq 'qcow2';
+    $lvmsize = "${lvmsize}k";
 
     my $path = $class->path($scfg, $volname);
-    my $cmd = ['/sbin/lvextend', '-L', $size, $path];
+    my $cmd = ['/sbin/lvextend', '-L', $lvmsize, $path];
 
     $class->cluster_lock_storage($storeid, $scfg->{shared}, undef, sub {
 	run_command($cmd, errmsg => "error resizing volume '$path'");
     });
 
+    if(!$running && $format eq 'qcow2') {
+	my $prealloc_opt = PVE::Storage::Plugin::preallocation_cmd_option($scfg, $format);
+	my $cmd = ['/usr/bin/qemu-img', 'resize', "--$prealloc_opt", '-f', $format, $path , $size];
+	run_command($cmd, timeout => 10);
+    }
+
     return 1;
 }
 
@@ -585,30 +653,149 @@ sub volume_size_info {
 sub volume_snapshot {
     my ($class, $scfg, $storeid, $volname, $snap) = @_;
 
-    die "lvm snapshot is not implemented";
+    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
+        $class->parse_volname($volname);
+
+    die "can't snapshot this image format\n" if $format ne 'qcow2';
+
+    $class->activate_volume($storeid, $scfg, $volname, undef, {});
+
+    my $snap_volname = $class->get_snap_volname($volname, $snap);
+    my $snap_path = $class->path($scfg, $volname, $storeid, $snap);
+
+    my $size = $class->volume_size_info($scfg, $storeid, $volname, 5);
+
+    #rename current lvm volume to snap volume
+    my $vg = $scfg->{vgname};
+    print"rename $volname to $snap_volname\n";
+    eval { lvrename($vg, $volname, $snap_volname) } ;
+
+
+    #allocate a new lvm volume
+    $class->alloc_new_image($storeid, $scfg, $vmid, 'qcow2', $volname, $size/1024);
+    eval {
+        $class->format_qcow2($storeid, $scfg, $volname, undef, $snap_path);
+    };
+
+    if ($@) {
+        eval { $class->free_image($storeid, $scfg, $volname, 0) };
+        warn $@ if $@;
+    }
+}
+
+sub volume_rollback_is_possible {
+    my ($class, $scfg, $storeid, $volname, $snap, $blockers) = @_;
+
+    my $snap_path = $class->path($scfg, $volname, $storeid, $snap);
+
+    my $snapshots = $class->volume_snapshot_info($scfg, $storeid, $volname);
+    my $parent_snap = $snapshots->{current}->{parent};
+
+    return 1 if !-e $snap_path || $snapshots->{$parent_snap}->{file} eq $snap_path;
+    die "can't rollback, '$snap' is not most recent snapshot on '$volname'\n";
+
+    return 1;
 }
 
+
 sub volume_snapshot_rollback {
     my ($class, $scfg, $storeid, $volname, $snap) = @_;
 
-    die "lvm snapshot rollback is not implemented";
+    die "can't rollback snapshot this image format\n" if $volname !~ m/\.(qcow2|qed)$/;
+
+    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
+        $class->parse_volname($volname);
+
+    $class->activate_volume($storeid, $scfg, $volname, undef, {});
+    my $size = $class->volume_size_info($scfg, $storeid, $volname, 5);
+    my $snap_path = $class->path($scfg, $volname, $storeid, $snap);
+
+    #simply delete the current snapshot and recreate it
+    $class->free_image($storeid, $scfg, $volname, 0);
+    $class->alloc_new_image($storeid, $scfg, $vmid, 'qcow2', $volname, $size/1024);
+    $class->format_qcow2($storeid, $scfg, $volname, undef, $snap_path);
+
+    return undef;
 }
 
 sub volume_snapshot_delete {
-    my ($class, $scfg, $storeid, $volname, $snap) = @_;
+    my ($class, $scfg, $storeid, $volname, $snap, $running) = @_;
+
+   die "can't delete snapshot for this image format\n" if $volname !~ m/\.(qcow2|qed)$/;
+
+   return 1 if $running;
+
+   my $cmd = "";
+   my $path = $class->filesystem_path($scfg, $volname);
+
+
+   my $snapshots = $class->volume_snapshot_info($scfg, $storeid, $volname);
+   my $snap_path = $snapshots->{$snap}->{file};
+   my $snap_volname = $snapshots->{$snap}->{volname};
+   return if !-e $snap_path;  #already deleted ?
+
+   my $parent_snap = $snapshots->{$snap}->{parent};
+   my $child_snap = $snapshots->{$snap}->{child};
+
+   my $parent_path = $snapshots->{$parent_snap}->{file} if $parent_snap;
+   my $child_path = $snapshots->{$child_snap}->{file} if $child_snap;
+   my $child_volname = $snapshots->{$child_snap}->{volname} if $child_snap;
+
+
+   #if first snapshot, we merge child, and rename the snapshot to child
+   if(!$parent_snap) {
+        #we use commit here, as it's faster than rebase
+        #https://lists.gnu.org/archive/html/qemu-discuss/2019-08/msg00041.html
+        print"commit $child_path\n";
+        $cmd = ['/usr/bin/qemu-img', 'commit', $child_path];
+        run_command($cmd);
+        print"delete $child_volname\n";
+        $class->free_image($storeid, $scfg, $child_volname, 0);
+
+        print"rename $snap_volname to $child_volname\n";
+	my $vg = $scfg->{vgname};
+        lvrename($vg, $snap_volname, $child_volname);
+    } else {
+        print"commit $snap_path\n";
+        $cmd = ['/usr/bin/qemu-img', 'commit', $snap_path];
+        #if we delete an intermediate snapshot, we need to link upper snapshot to base snapshot
+        die "missing parentsnap snapshot to rebase child $child_path\n" if !$parent_path;
+        print "link $child_snap to $parent_snap\n";
+        $cmd = ['/usr/bin/qemu-img', 'rebase', '-u', '-b', $parent_path, '-F', 'qcow2', '-f', 'qcow2', $child_path];
+        run_command($cmd);
+        #delete the snapshot
+        $class->free_image($storeid, $scfg, $snap_volname, 0);
+    }
 
-    die "lvm snapshot delete is not implemented";
 }
 
 sub volume_has_feature {
     my ($class, $scfg, $feature, $storeid, $volname, $snapname, $running) = @_;
 
     my $features = {
-	copy => { base => 1, current => 1},
-	rename => {current => 1},
+        copy => {
+            base => { qcow2 => 1, raw => 1},
+            current => { qcow2 => 1, raw => 1},
+            snap => { qcow2 => 1 },
+        },
+        'rename' => {
+            current => { qcow2 => 1, raw => 1},
+        },
+        snapshot => {
+            current => { qcow2 => 1 },
+            snap => { qcow2 => 1 },
+        },
+        template => {
+            current => { qcow2 => 1, raw => 1},
+        },
+#	don't allow to clone as we can't activate the base on multiple host at the same time
+#       clone => {
+#           base => { qcow2 => 1, raw => 1},
+#       },
     };
 
-    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase) =
+
+    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
 	$class->parse_volname($volname);
 
     my $key = undef;
@@ -617,7 +804,7 @@ sub volume_has_feature {
     }else{
 	$key =  $isBase ? 'base' : 'current';
     }
-    return 1 if $features->{$feature}->{$key};
+    return 1 if defined($features->{$feature}->{$key}->{$format});
 
     return undef;
 }
@@ -738,4 +925,12 @@ sub rename_volume {
     return "${storeid}:${target_volname}";
 }
 
+sub get_snap_volname {
+    my ($class, $volname, $snapname) = @_;
+
+    my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) = $class->parse_volname($volname);
+    $name = !$snapname || $snapname eq 'current' ? $volname : "snap-$snapname-$name";
+    return $name;
+}
+
 1;
-- 
2.39.5



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