[PATCH qemu-server 2/3] blockdev: add backing_chain support
Alexandre Derumier
alexandre.derumier at groupe-cyllene.com
Fri Jul 4 08:44:57 CEST 2025
We need to define name-nodes for all backing chain images,
to be able to live rename them with blockdev-reopen
For linked clone, we don't need to definebase image(s) chain.
They are auto added with #block nodename.
Signed-off-by: Alexandre Derumier <alexandre.derumier at groupe-cyllene.com>
---
src/PVE/QemuServer/Blockdev.pm | 49 +++++++++++++++++++
src/test/cfg2cmd/simple-backingchain.conf | 25 ++++++++++
src/test/cfg2cmd/simple-backingchain.conf.cmd | 33 +++++++++++++
src/test/run_config2command_tests.pl | 47 ++++++++++++++++++
4 files changed, 154 insertions(+)
create mode 100644 src/test/cfg2cmd/simple-backingchain.conf
create mode 100644 src/test/cfg2cmd/simple-backingchain.conf.cmd
diff --git a/src/PVE/QemuServer/Blockdev.pm b/src/PVE/QemuServer/Blockdev.pm
index 5f1fdae3..2a0513fb 100644
--- a/src/PVE/QemuServer/Blockdev.pm
+++ b/src/PVE/QemuServer/Blockdev.pm
@@ -360,6 +360,46 @@ my sub generate_format_blockdev {
return $blockdev;
}
+my sub generate_backing_blockdev;
+
+sub generate_backing_blockdev {
+ my ($storecfg, $snapshots, $deviceid, $drive, $machine_version, $options) = @_;
+
+ my $snap_id = $options->{'snapshot-name'};
+ my $snapshot = $snapshots->{$snap_id};
+ my $parentid = $snapshot->{parent};
+
+ my $volid = $drive->{file};
+
+ my $snap_file_blockdev = generate_file_blockdev($storecfg, $drive, $machine_version, $options);
+ $snap_file_blockdev->{filename} = $snapshot->{file};
+
+ my $snap_fmt_blockdev =
+ generate_format_blockdev($storecfg, $drive, $snap_file_blockdev, $options);
+
+ if ($parentid) {
+ my $options = { 'snapshot-name' => $parentid };
+ $snap_fmt_blockdev->{backing} = generate_backing_blockdev(
+ $storecfg, $snapshots, $deviceid, $drive, $machine_version, $options,
+ );
+ }
+ return $snap_fmt_blockdev;
+}
+
+my sub generate_backing_chain_blockdev {
+ my ($storecfg, $deviceid, $drive, $machine_version) = @_;
+
+ my $volid = $drive->{file};
+
+ my $snapshots = PVE::Storage::volume_snapshot_info($storecfg, $volid);
+ my $parentid = $snapshots->{'current'}->{parent};
+ return undef if !$parentid;
+ my $options = { 'snapshot-name' => $parentid };
+ return generate_backing_blockdev(
+ $storecfg, $snapshots, $deviceid, $drive, $machine_version, $options,
+ );
+}
+
sub generate_drive_blockdev {
my ($storecfg, $drive, $machine_version, $options) = @_;
@@ -371,6 +411,15 @@ sub generate_drive_blockdev {
my $child = generate_file_blockdev($storecfg, $drive, $machine_version, $options);
if (!is_nbd($drive)) {
$child = generate_format_blockdev($storecfg, $drive, $child, $options);
+
+ my $support_qemu_snapshots =
+ PVE::Storage::volume_support_qemu_snapshot($storecfg, $drive->{file});
+ if ($support_qemu_snapshots && $support_qemu_snapshots eq 'external') {
+ my $backing_chain = generate_backing_chain_blockdev(
+ $storecfg, "drive-$drive_id", $drive, $machine_version,
+ );
+ $child->{backing} = $backing_chain if $backing_chain;
+ }
}
if ($options->{'zero-initialized'}) {
diff --git a/src/test/cfg2cmd/simple-backingchain.conf b/src/test/cfg2cmd/simple-backingchain.conf
new file mode 100644
index 00000000..2c0b0f2c
--- /dev/null
+++ b/src/test/cfg2cmd/simple-backingchain.conf
@@ -0,0 +1,25 @@
+# TEST: Simple test for external snapshot backing chain
+name: simple
+parent: snap3
+scsi0: localsnapext:8006/vm-8006-disk-0.qcow2,size=1G
+scsi1: lvm-store:vm-8006-disk-0.qcow2,size=1G
+
+[snap1]
+name: simple
+scsi0: localsnapext:8006/vm-8006-disk-0.qcow2,size=1G
+scsi1: lvm-store:vm-8006-disk-0.qcow2,size=1G
+snaptime: 1748933042
+
+[snap2]
+parent: snap1
+name: simple
+scsi0: localsnapext:8006/vm-8006-disk-0.qcow2,size=1G
+scsi1: lvm-store:vm-8006-disk-0.qcow2,size=1G
+snaptime: 1748933043
+
+[snap3]
+parent: snap2
+name: simple
+scsi0: localsnapext:8006/vm-8006-disk-0.qcow2,size=1G
+scsi1: lvm-store:vm-8006-disk-0.qcow2,size=1G
+snaptime: 1748933044
diff --git a/src/test/cfg2cmd/simple-backingchain.conf.cmd b/src/test/cfg2cmd/simple-backingchain.conf.cmd
new file mode 100644
index 00000000..40c957f5
--- /dev/null
+++ b/src/test/cfg2cmd/simple-backingchain.conf.cmd
@@ -0,0 +1,33 @@
+/usr/bin/kvm \
+ -id 8006 \
+ -name 'simple,debug-threads=on' \
+ -no-shutdown \
+ -chardev 'socket,id=qmp,path=/var/run/qemu-server/8006.qmp,server=on,wait=off' \
+ -mon 'chardev=qmp,mode=control' \
+ -chardev 'socket,id=qmp-event,path=/var/run/qmeventd.sock,reconnect-ms=5000' \
+ -mon 'chardev=qmp-event,mode=control' \
+ -pidfile /var/run/qemu-server/8006.pid \
+ -daemonize \
+ -smp '1,sockets=1,cores=1,maxcpus=1' \
+ -nodefaults \
+ -boot 'menu=on,strict=on,reboot-timeout=1000,splash=/usr/share/qemu-server/bootsplash.jpg' \
+ -vnc 'unix:/var/run/qemu-server/8006.vnc,password=on' \
+ -cpu kvm64,enforce,+kvm_pv_eoi,+kvm_pv_unhalt,+lahf_lm,+sep \
+ -m 512 \
+ -object '{"id":"throttle-drive-scsi0","limits":{},"qom-type":"throttle-group"}' \
+ -object '{"id":"throttle-drive-scsi1","limits":{},"qom-type":"throttle-group"}' \
+ -global 'PIIX4_PM.disable_s3=1' \
+ -global 'PIIX4_PM.disable_s4=1' \
+ -device 'pci-bridge,id=pci.1,chassis_nr=1,bus=pci.0,addr=0x1e' \
+ -device 'pci-bridge,id=pci.2,chassis_nr=2,bus=pci.0,addr=0x1f' \
+ -device 'piix3-usb-uhci,id=uhci,bus=pci.0,addr=0x1.0x2' \
+ -device 'usb-tablet,id=tablet,bus=uhci.0,port=1' \
+ -device 'VGA,id=vga,bus=pci.0,addr=0x2' \
+ -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3,free-page-reporting=on' \
+ -iscsi 'initiator-name=iqn.1993-08.org.debian:01:aabbccddeeff' \
+ -device 'lsi,id=scsihw0,bus=pci.0,addr=0x5' \
+ -blockdev '{"driver":"throttle","file":{"backing":{"backing":{"cache":{"direct":true,"no-flush":false},"driver":"qcow2","file":{"aio":"io_uring","cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"file","filename":"/var/lib/vzsnapext/images/8006/snap1-vm-8006-disk-0.qcow2","node-name":"ea91a385a49a008a4735c0aec5c6749","read-only":false},"node-name":"fa91a385a49a008a4735c0aec5c6749","read-only":false},"cache":{"direct":true,"no-flush":false},"driver":"qcow2","file":{"aio":"io_uring","cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"file","filename":"/var/lib/vzsnapext/images/8006/snap2-vm-8006-disk-0.qcow2","node-name":"ec0289317073959d450248d8cd7a480","read-only":false},"node-name":"fc0289317073959d450248d8cd7a480","read-only":false},"cache":{"direct":true,"no-flush":false},"driver":"qcow2","file":{"aio":"io_uring","cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"file","filename":"/var/lib/vzsnapext/images/8006/vm-8006-disk-0.qcow2","node-name":"e74f4959037afb46eddc7313c43dfdd","read-only":false},"node-name":"f74f4959037afb46eddc7313c43dfdd","read-only":false},"node-name":"drive-scsi0","throttle-group":"throttle-drive-scsi0"}' \
+ -device 'scsi-hd,bus=scsihw0.0,scsi-id=0,drive=drive-scsi0,id=scsi0,write-cache=on' \
+ -blockdev '{"driver":"throttle","file":{"backing":{"backing":{"cache":{"direct":true,"no-flush":false},"driver":"qcow2","file":{"aio":"native","cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"host_device","filename":"/dev/veegee/snap1-vm-8006-disk-0.qcow2","node-name":"e25f58d3e6e11f2065ad41253988915","read-only":false},"node-name":"f25f58d3e6e11f2065ad41253988915","read-only":false},"cache":{"direct":true,"no-flush":false},"driver":"qcow2","file":{"aio":"native","cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"host_device","filename":"/dev/veegee/snap2-vm-8006-disk-0.qcow2","node-name":"e9415bb5e484c1e25d25063b01686fe","read-only":false},"node-name":"f9415bb5e484c1e25d25063b01686fe","read-only":false},"cache":{"direct":true,"no-flush":false},"driver":"qcow2","file":{"aio":"native","cache":{"direct":true,"no-flush":false},"detect-zeroes":"on","discard":"ignore","driver":"host_device","filename":"/dev/veegee/vm-8006-disk-0.qcow2","node-name":"e87358a470ca311f94d5cc61d1eb428","read-only":false},"node-name":"f87358a470ca311f94d5cc61d1eb428","read-only":false},"node-name":"drive-scsi1","throttle-group":"throttle-drive-scsi1"}' \
+ -device 'scsi-hd,bus=scsihw0.0,scsi-id=1,drive=drive-scsi1,id=scsi1,write-cache=on' \
+ -machine 'type=pc+pve0'
diff --git a/src/test/run_config2command_tests.pl b/src/test/run_config2command_tests.pl
index 1262a0df..61302f6b 100755
--- a/src/test/run_config2command_tests.pl
+++ b/src/test/run_config2command_tests.pl
@@ -21,6 +21,7 @@ use PVE::QemuServer::Helpers;
use PVE::QemuServer::Monitor;
use PVE::QemuServer::QMPHelpers;
use PVE::QemuServer::CPUConfig;
+use PVE::Storage;
my $base_env = {
storage_config => {
@@ -34,6 +35,15 @@ my $base_env = {
type => 'dir',
shared => 0,
},
+ localsnapext => {
+ content => {
+ images => 1,
+ },
+ path => '/var/lib/vzsnapext',
+ type => 'dir',
+ shared => 0,
+ snapext => 1,
+ },
noimages => {
content => {
iso => 1,
@@ -264,6 +274,43 @@ $storage_module->mock(
deactivate_volumes => sub {
return;
},
+ volume_snapshot_info => sub {
+ my ($cfg, $volid) = @_;
+
+ my ($storeid, $volname) = PVE::Storage::parse_volume_id($volid);
+
+ my $snapshots = {};
+ if ($storeid eq 'localsnapext') {
+ $snapshots = {
+ current => {
+ file => 'var/lib/vzsnapext/images/8006/vm-8006-disk-0.qcow2',
+ parent => 'snap2',
+ },
+ snap2 => {
+ file => '/var/lib/vzsnapext/images/8006/snap2-vm-8006-disk-0.qcow2',
+ parent => 'snap1',
+ },
+ snap1 => {
+ file => '/var/lib/vzsnapext/images/8006/snap1-vm-8006-disk-0.qcow2',
+ },
+ };
+ } elsif ($storeid eq 'lvm-store') {
+ $snapshots = {
+ current => {
+ file => '/dev/veegee/vm-8006-disk-0.qcow2',
+ parent => 'snap2',
+ },
+ snap2 => {
+ file => '/dev/veegee/snap2-vm-8006-disk-0.qcow2',
+ parent => 'snap1',
+ },
+ snap1 => {
+ file => '/dev/veegee/snap1-vm-8006-disk-0.qcow2',
+ },
+ };
+ }
+ return $snapshots;
+ },
);
my $file_stat_module = Test::MockModule->new("File::stat");
--
2.39.5
More information about the pve-devel
mailing list