[PATCH pve-storage 3/5] lvmplugin: add qcow2 snapshot
Alexandre Derumier
alexandre.derumier at groupe-cyllene.com
Tue Apr 22 13:51:28 CEST 2025
we format lvm logical volume with qcow2 to handle snapshot chain.
like for qcow2 file, when a snapshot is taken, the current lvm volume
is renamed to snap volname, and a new current lvm volume is created
with the snap volname as backing file
Signed-off-by: Alexandre Derumier <alexandre.derumier at groupe-cyllene.com>
---
src/PVE/Storage/LVMPlugin.pm | 301 ++++++++++++++++++++++++++++++++---
1 file changed, 278 insertions(+), 23 deletions(-)
diff --git a/src/PVE/Storage/LVMPlugin.pm b/src/PVE/Storage/LVMPlugin.pm
index c4648ec..8ee337a 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;
@@ -218,6 +219,7 @@ sub type {
sub plugindata {
return {
content => [ {images => 1, rootdir => 1}, { images => 1 }],
+ format => [ { raw => 1, qcow2 => 1 } , 'raw' ],
'sensitive-properties' => {},
};
}
@@ -294,7 +296,10 @@ 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";
@@ -303,11 +308,13 @@ 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 = $class->get_snap_name($volname, $snapname) if $snapname;
my $path = "/dev/$vg/$name";
@@ -335,7 +342,9 @@ 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, $add_fmt_suffix);
}
sub lvcreate {
@@ -363,13 +372,43 @@ sub lvrename {
);
}
-sub alloc_image {
- my ($class, $storeid, $scfg, $vmid, $fmt, $name, $size) = @_;
+my sub lvm_qcow2_format {
+ my ($class, $storeid, $scfg, $name, $fmt, $backing_snap, $size) = @_;
+
+ return if $fmt ne 'qcow2';
+
+ $class->activate_volume($storeid, $scfg, $name);
+ my $path = $class->path($scfg, $name, $storeid);
+ my $backing_path = $class->path($scfg, $name, $storeid, $backing_snap) if $backing_snap;
+ PVE::Storage::Plugin::qemu_img_create($scfg, 'qcow2', $size, $path, $backing_path);
- die "unsupported format '$fmt'" if $fmt ne 'raw';
+}
+
+my sub lvm_size {
+ my ($size, $fmt, $backing_snap) = @_;
+
+ #add extra space for qcow2 metadatas for initial image
+ #if backing_snap exist, the parent lvm volume already have the overhead
+ return $size if $fmt ne 'qcow2' || $backing_snap;
+
+ #without sub-allocated clusters : l2_size = disk_size × 8 / cluster_size
+ #with sub-allocated clusters : l2_size = disk_size × 8 / cluster_size / 16
+ #ex: 4MB overhead for 1TB with extented l2 clustersize=128k
+ #can't use qemu-img measure, because it's not possible to define options like clustersize && extended_l2
+ #verification has been done with : qemu-img create -f qcow2 -o extended_l2=on,cluster_size=128k test.img 1G
+
+ my $qcow2_overhead = ceil($size/1024/1024/1024) * 4096;
+ $size += $qcow2_overhead;
+ return $size;
+}
+
+my sub alloc_lvm_image {
+ my ($class, $storeid, $scfg, $vmid, $fmt, $name, $size, $backing_snap) = @_;
+
+ die "unsupported format '$fmt'" if $fmt !~ m/(raw|qcow2)/;
die "illegal name '$name' - should be 'vm-$vmid-*'\n"
- if $name && $name !~ m/^vm-$vmid-/;
+ if $name !~ m/^vm-$vmid-/;
my $vgs = lvm_vgs();
@@ -378,17 +417,51 @@ sub alloc_image {
die "no such volume group '$vg'\n" if !defined ($vgs->{$vg});
my $free = int($vgs->{$vg}->{free});
+ my $lvmsize = lvm_size($size, $fmt, $backing_snap);
die "not enough free space ($free < $size)\n" if $free < $size;
- $name = $class->find_free_diskname($storeid, $scfg, $vmid)
+ my $tags = ["pve-vm-$vmid"];
+ #tags all snapshots volumes with the main volume tag for easier activation of the whole group
+ push @$tags, "\@pve-$name" if $fmt eq 'qcow2';
+ lvcreate($vg, $name, $lvmsize, $tags);
+
+ #format the lvm volume with qcow2 format
+ eval { lvm_qcow2_format($class, $storeid, $scfg, $name, $fmt, $backing_snap, $size) };
+ if ($@) {
+ my $err = $@;
+ #no need to safe cleanup as the volume is still empty
+ eval {
+ my $cmd = ['/sbin/lvremove', '-f', "$vg/$name"];
+ run_command($cmd, errmsg => "lvremove '$vg/$name' error");
+ };
+ die $err;
+ }
+
+}
+
+sub alloc_image {
+ my ($class, $storeid, $scfg, $vmid, $fmt, $name, $size) = @_;
+
+ $name = $class->find_free_diskname($storeid, $scfg, $vmid, $fmt)
if !$name;
- lvcreate($vg, $name, $size, ["pve-vm-$vmid"]);
+ alloc_lvm_image($class, $storeid, $scfg, $vmid, $fmt, $name, $size);
return $name;
}
+sub alloc_snap_image {
+ my ($class, $storeid, $scfg, $volname, $backing_snap) = @_;
+
+ my $size = $class->volume_size_info($scfg, $storeid, $volname, 5, $backing_snap);
+ $size = $size / 1024; #we use kb in lvcreate
+
+ my ($vmid, $format) = ($class->parse_volname($volname))[2,6];
+
+ alloc_lvm_image($class, $storeid, $scfg, $vmid, $format, $volname, $size, $backing_snap);
+}
+
sub free_image {
my ($class, $storeid, $scfg, $volname, $isBase) = @_;
@@ -539,6 +612,12 @@ 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];
@@ -551,6 +630,10 @@ 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 '$path'");
}
@@ -558,21 +641,31 @@ sub deactivate_volume {
sub volume_resize {
my ($class, $scfg, $storeid, $volname, $size, $running) = @_;
- $size = ($size/1024/1024) . "M";
+ my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
+ $class->parse_volname($volname);
+
+ my $lvmsize = lvm_size($size/1024, $format);
+ $lvmsize = "${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;
}
sub volume_size_info {
- my ($class, $scfg, $storeid, $volname, $timeout) = @_;
- my $path = $class->filesystem_path($scfg, $volname);
+ my ($class, $scfg, $storeid, $volname, $timeout, $snap) = @_;
+ my $path = $class->filesystem_path($scfg, $volname, $snap);
my $cmd = ['/sbin/lvs', '--separator', ':', '--noheadings', '--units', 'b',
'--unbuffered', '--nosuffix', '--options', 'lv_size', $path];
@@ -586,32 +679,180 @@ sub volume_size_info {
}
sub volume_snapshot {
- my ($class, $scfg, $storeid, $volname, $snap) = @_;
+ my ($class, $scfg, $storeid, $volname, $snap, $running) = @_;
+
+ my ($vmid, $format) = ($class->parse_volname($volname))[2,6];
+
+ die "can't snapshot this image format\n" if $format ne 'qcow2';
+
+ if ($running) {
+ #rename with blockdev-reopen is done at qemu level when running
+ $class->alloc_snap_image($storeid, $scfg, $volname, $snap);
+ if ($@) {
+ die "can't allocate new volume $volname: $@\n";
+ }
+ return;
+ }
+
+ #rename current volume to snap volume
+ eval { $class->rename_volume($scfg, $storeid, $volname, $vmid, undef, 'current', $snap) };
+ die "error rename $volname to $snap\n" if $@;
+
+ eval { $class->alloc_snap_image($storeid, $scfg, $volname, $snap) };
+ if ($@) {
+ my $err = $@;
+ eval { $class->rename_volume($scfg, $storeid, $volname, $vmid, undef, $snap, 'current') };
+ die $err;
+ }
+}
+
+sub volume_rollback_is_possible {
+ my ($class, $scfg, $storeid, $volname, $snap, $blockers) = @_;
+
+ my $snap_path = $class->path($scfg, $volname, $storeid, $snap);
- die "lvm snapshot is not implemented";
+ $class->activate_volume($storeid, $scfg, $volname, undef, {});
+ my $snapshots = $class->volume_snapshot_info($scfg, $storeid, $volname);
+ my $parent_snap = $snapshots->{current}->{parent};
+
+ return 1 if $parent_snap eq $snap;
+ die "can't rollback, '$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";
+ my $format = ($class->parse_volname($volname))[6];
+
+ die "can't rollback snapshot for this image format\n" if $format ne 'qcow2';
+
+ $class->activate_volume($storeid, $scfg, $volname, undef, {});
+
+ # we can simply reformat the current lvm volume to avoid
+ # a long safe remove.(not needed here, as the allocated space
+ # is still the same owner)
+ eval { lvm_qcow2_format($class, $storeid, $scfg, $volname, $format, $snap) };
+ if($@) {
+ die "can't rollback. Error reformating current $volname\n";
+ }
+ return undef;
}
sub volume_snapshot_delete {
- my ($class, $scfg, $storeid, $volname, $snap) = @_;
+ my ($class, $scfg, $storeid, $volname, $snap, $running) = @_;
+
+ my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) = $class->parse_volname($volname);
+
+ die "can't delete snapshot for this image format\n" if $format ne 'qcow2';
+
+ if ($running) {
+ $volname = $class->get_snap_volname($volname, $snap);
+ my $cleanup_worker = eval { $class->free_image($storeid, $scfg, $volname, $isBase, $format) };
+ die "error deleting snapshot $snap\n" if $@;
+
+ if ($cleanup_worker) {
+ my $rpcenv = PVE::RPCEnvironment::get();
+ my $authuser = $rpcenv->get_user();
+ $rpcenv->fork_worker('imgdel', undef, $authuser, $cleanup_worker);
+ }
+ return;
+ }
- die "lvm snapshot delete is not implemented";
+ my $cmd = "";
+ my $path = $class->filesystem_path($scfg, $volname);
+
+ my $snapshots = $class->volume_snapshot_info($scfg, $storeid, $volname);
+ my $snappath = $snapshots->{$snap}->{file};
+ my $snapvolname = $snapshots->{$snap}->{volname};
+ die "volume $snappath is missing" if !-e $snappath;
+
+ my $parentsnap = $snapshots->{$snap}->{parent};
+
+ my $childsnap = $snapshots->{$snap}->{child};
+ my $childpath = $snapshots->{$childsnap}->{file};
+ my $childvolname = $snapshots->{$childsnap}->{volname};
+
+ my $cleanup_worker = undef;
+ my $err = undef;
+ #if first snapshot,as it should be bigger, we merge child, and rename the snapshot to child
+ if(!$parentsnap) {
+ print "commit: merge content of $childpath into $snappath\n";
+ #can't use -d here, as it's an lvm volume
+ $cmd = ['/usr/bin/qemu-img', 'commit', $childpath];
+ eval { run_command($cmd) };
+ if ($@) {
+ die "error commiting $childpath to $snappath; $@\n";
+ }
+ print"delete $childvolname\n";
+
+ $cleanup_worker = eval { $class->free_image($storeid, $scfg, $childvolname, 0) };
+ if ($@) {
+ die "error delete old snapshot volume $childvolname: $@\n";
+ }
+
+ print"rename $snapvolname to $childvolname\n";
+ my $vg = $scfg->{vgname};
+ eval { lvrename($vg, $snapvolname, $childvolname) };
+ if ($@) {
+ warn $@;
+ $err = "error renaming snapshot: $@\n";
+ }
+
+ } else {
+ #we rebase the child image on the parent as new backing image
+ my $parentpath = $snapshots->{$parentsnap}->{file};
+ print "rebase: merge diff content between $parentpath and $childpath into $childpath\n";
+ $cmd = ['/usr/bin/qemu-img', 'rebase', '-b', $parentpath, '-F', 'qcow2', '-f', 'qcow2', $childpath];
+ eval { run_command($cmd) };
+ if ($@) {
+ die "error rebase $childpath from $parentpath; $@\n";
+ }
+ #delete the snapshot
+ eval { $cleanup_worker = $class->free_image($storeid, $scfg, $snapvolname, 0); };
+ if ($@) {
+ die "error delete old snapshot volume $snapvolname\n";
+ }
+ }
+
+ if ($cleanup_worker) {
+ my $rpcenv = PVE::RPCEnvironment::get();
+ my $authuser = $rpcenv->get_user();
+ $rpcenv->fork_worker('imgdel', undef, $authuser, $cleanup_worker);
+ }
+
+ die $err if $err;
}
sub volume_has_feature {
my ($class, $scfg, $feature, $storeid, $volname, $snapname, $running) = @_;
my $features = {
- copy => { base => 1, current => 1},
- rename => {current => 1},
+ copy => {
+ base => { qcow2 => 1, raw => 1 },
+ current => { qcow2 => 1, raw => 1},
+ snap => { qcow2 => 1 },
+ },
+ 'rename' => {
+ current => { qcow2 => 1, raw => 1},
+ },
+ snapshot => {
+ current => { qcow2 => 1 },
+ snap => { qcow2 => 1 },
+ },
+# fixme: add later ? (we need to handle basepath, volume activation,...)
+# template => {
+# current => { raw => 1, qcow2 => 1},
+# },
+# clone => {
+# base => { qcow2 => 1 },
+# },
};
- my ($vtype, $name, $vmid, $basename, $basevmid, $isBase) =
+
+ my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) =
$class->parse_volname($volname);
my $key = undef;
@@ -620,7 +861,7 @@ sub volume_has_feature {
}else{
$key = $isBase ? 'base' : 'current';
}
- return 1 if $features->{$feature}->{$key};
+ return 1 if defined($features->{$feature}->{$key}->{$format});
return undef;
}
@@ -745,4 +986,18 @@ sub rename_volume {
return "${storeid}:${target_volname}";
}
+sub get_snap_name {
+ my ($class, $volname, $snapname) = @_;
+
+ my ($vtype, $name, $vmid, $basename, $basevmid, $isBase, $format) = $class->parse_volname($volname);
+ $name = !$snapname || $snapname eq 'current' ? $name : "snap-$snapname-$name";
+ return $name;
+}
+
+sub get_snap_volname {
+ my ($class, $volname, $snapname) = @_;
+
+ return $class->get_snap_name($volname, $snapname);
+}
+
1;
--
2.39.5
More information about the pve-devel
mailing list