[PATCH qemu-server 13/13] qcow2: add external snapshot support
Alexandre Derumier
alexandre.derumier at groupe-cyllene.com
Tue Jun 3 09:55:58 CEST 2025
fixme:
- add test for internal (was missing) && external qemu snapshots
- is it possible to use blockjob transactions for commit && steam
for atomatic disk commit ?
Signed-off-by: Alexandre Derumier <alexandre.derumier at groupe-cyllene.com>
---
PVE/QemuConfig.pm | 4 +-
PVE/QemuServer.pm | 79 ++++++++++-----
PVE/QemuServer/Blockdev.pm | 199 ++++++++++++++++++++++++++++++++++---
test/snapshot-test.pm | 4 +-
4 files changed, 245 insertions(+), 41 deletions(-)
diff --git a/PVE/QemuConfig.pm b/PVE/QemuConfig.pm
index 2609542c..785c84a2 100644
--- a/PVE/QemuConfig.pm
+++ b/PVE/QemuConfig.pm
@@ -378,7 +378,7 @@ sub __snapshot_create_vol_snapshot {
print "snapshotting '$device' ($drive->{file})\n";
- PVE::QemuServer::qemu_volume_snapshot($vmid, $device, $storecfg, $volid, $snapname);
+ PVE::QemuServer::qemu_volume_snapshot($vmid, $device, $storecfg, $drive, $snapname);
}
sub __snapshot_delete_remove_drive {
@@ -415,7 +415,7 @@ sub __snapshot_delete_vol_snapshot {
my $storecfg = PVE::Storage::config();
my $volid = $drive->{file};
- PVE::QemuServer::qemu_volume_snapshot_delete($vmid, $storecfg, $volid, $snapname);
+ PVE::QemuServer::qemu_volume_snapshot_delete($vmid, $storecfg, $drive, $snapname);
push @$unused, $volid;
}
diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 53135894..9857c536 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -52,7 +52,7 @@ use PVE::QMPClient;
use PVE::QemuConfig;
use PVE::QemuConfig::NoWrite;
use PVE::QemuServer::Helpers qw(config_aware_timeout min_version kvm_user_version windows_version);
-use PVE::QemuServer::Blockdev qw(generate_drive_blockdev generate_throttle_group);
+use PVE::QemuServer::Blockdev qw(generate_drive_blockdev generate_throttle_group blockdev_external_snapshot blockdev_delete blockdev_rename blockdev_commit blockdev_stream);
use PVE::QemuServer::Cloudinit;
use PVE::QemuServer::CGroup;
use PVE::QemuServer::CPUConfig qw(print_cpu_device get_cpu_options get_cpu_bitness is_native_arch get_amd_sev_object get_amd_sev_type);
@@ -4677,20 +4677,37 @@ sub qemu_block_resize {
}
sub qemu_volume_snapshot {
- my ($vmid, $deviceid, $storecfg, $volid, $snap) = @_;
+ my ($vmid, $deviceid, $storecfg, $drive, $snap) = @_;
+ my $volid = $drive->{file};
my $running = check_running($vmid);
- if ($running && do_snapshots_with_qemu($storecfg, $volid, $deviceid)) {
+ my $do_snapshots_type = do_snapshots_type($storecfg, $volid, $deviceid, $running);
+
+ if ($do_snapshots_type eq 'internal') {
+ print "internal qemu snapshot\n";
mon_cmd($vmid, 'blockdev-snapshot-internal-sync', device => $deviceid, name => $snap);
- } else {
+ } elsif ($do_snapshots_type eq 'external') {
+ my $storeid = (PVE::Storage::parse_volume_id($volid))[0];
+ my $scfg = PVE::Storage::storage_config($storecfg, $storeid);
+ print "external qemu snapshot\n";
+ my $snapshots = PVE::Storage::volume_snapshot_info($storecfg, $volid);
+ my $parent_snap = $snapshots->{'current'}->{parent};
+ blockdev_rename($storecfg, $vmid, $deviceid, $drive, 'current', $snap, $parent_snap);
+ eval { blockdev_external_snapshot($storecfg, $vmid, $deviceid, $drive, $snap) };
+ if ($@) {
+ print "error creating snapshot. Revert rename\n";
+ eval { blockdev_rename($storecfg, $vmid, $deviceid, $drive, $snap, 'current', $parent_snap) };
+ }
+ } elsif ($do_snapshots_type eq 'storage') {
PVE::Storage::volume_snapshot($storecfg, $volid, $snap);
}
}
sub qemu_volume_snapshot_delete {
- my ($vmid, $storecfg, $volid, $snap) = @_;
+ my ($vmid, $storecfg, $drive, $snap) = @_;
+ my $volid = $drive->{file};
my $running = check_running($vmid);
my $attached_deviceid;
@@ -4702,14 +4719,35 @@ sub qemu_volume_snapshot_delete {
});
}
- if ($attached_deviceid && do_snapshots_with_qemu($storecfg, $volid, $attached_deviceid)) {
+ my $do_snapshots_type = do_snapshots_type($storecfg, $volid, $attached_deviceid, $running);
+
+ if ($do_snapshots_type eq 'internal') {
mon_cmd(
$vmid,
'blockdev-snapshot-delete-internal-sync',
device => $attached_deviceid,
name => $snap,
);
- } else {
+ } elsif ($do_snapshots_type eq 'external') {
+ print "delete qemu external snapshot\n";
+
+ my $path = PVE::Storage::path($storecfg, $volid);
+ my $snapshots = PVE::Storage::volume_snapshot_info($storecfg, $volid);
+ my $parentsnap = $snapshots->{$snap}->{parent};
+ my $childsnap = $snapshots->{$snap}->{child};
+
+ # if we delete the first snasphot, we commit because the first snapshot original base image, it should be big.
+ # improve-me: if firstsnap > child : commit, if firstsnap < child do a stream.
+ if(!$parentsnap) {
+ print"delete first snapshot $snap\n";
+ blockdev_commit($storecfg, $vmid, $attached_deviceid, $drive, $childsnap, $snap);
+ blockdev_rename($storecfg, $vmid, $attached_deviceid, $drive, $snap, $childsnap, $snapshots->{$childsnap}->{child});
+ } else {
+ #intermediate snapshot, we always stream the snapshot to child snapshot
+ print"stream intermediate snapshot $snap to $childsnap\n";
+ blockdev_stream($storecfg, $vmid, $attached_deviceid, $drive, $snap, $parentsnap, $childsnap);
+ }
+ } elsif ($do_snapshots_type eq 'storage') {
PVE::Storage::volume_snapshot_delete(
$storecfg, $volid, $snap, $attached_deviceid ? 1 : undef);
}
@@ -7976,27 +8014,20 @@ sub foreach_storage_used_by_vm {
}
}
-my $qemu_snap_storage = {
- rbd => 1,
-};
-sub do_snapshots_with_qemu {
- my ($storecfg, $volid, $deviceid) = @_;
+sub do_snapshots_type {
+ my ($storecfg, $volid, $deviceid, $running) = @_;
- return if $deviceid =~ m/tpmstate0/;
+ #we skip snapshot for tpmstate
+ return if $deviceid && $deviceid =~ m/tpmstate0/;
- my $storage_name = PVE::Storage::parse_volume_id($volid);
- my $scfg = $storecfg->{ids}->{$storage_name};
- die "could not find storage '$storage_name'\n" if !defined($scfg);
+ #we use storage snapshot if vm is not running or if disk is unused;
+ return 'storage' if !$running || !$deviceid;
- if ($qemu_snap_storage->{$scfg->{type}} && !$scfg->{krbd}){
- return 1;
- }
+ my $qemu_snapshot_type = PVE::Storage::volume_support_qemu_snapshot($storecfg, $volid);
+ # if running, but don't support qemu snapshot, we use storage snapshot
+ return 'storage' if !$qemu_snapshot_type;
- if ($volid =~ m/\.(qcow2|qed)$/){
- return 1;
- }
-
- return;
+ return $qemu_snapshot_type;
}
sub qga_check_running {
diff --git a/PVE/QemuServer/Blockdev.pm b/PVE/QemuServer/Blockdev.pm
index 692336c1..3a199c9e 100644
--- a/PVE/QemuServer/Blockdev.pm
+++ b/PVE/QemuServer/Blockdev.pm
@@ -3,6 +3,8 @@ package PVE::QemuServer::Blockdev;
use strict;
use warnings;
+use PVE::QemuServer;
+use PVE::QemuServer::Monitor qw(mon_cmd);
use PVE::QemuServer::Drive qw(checked_volume_format drive_is_cdrom drive_uses_cache_direct get_drive_id get_iso_path storage_allows_io_uring_default);
use PVE::Storage;
@@ -11,6 +13,11 @@ use base qw(Exporter);
our @EXPORT_OK = qw(
generate_drive_blockdev
generate_throttle_group
+blockdev_external_snapshot
+blockdev_delete
+blockdev_rename
+blockdev_commit
+blockdev_stream
);
sub encode_base62 {
@@ -134,6 +141,8 @@ sub print_drive_throttle_group {
sub generate_file_blockdev {
my ($storecfg, $drive, $snap, $nodename) = @_;
+ $snap = undef if $snap && $snap eq 'current';
+
my $volid = $drive->{file};
my $drive_id = get_drive_id($drive);
my $blockdev = {};
@@ -200,6 +209,8 @@ sub generate_file_blockdev {
sub generate_format_blockdev {
my ($storecfg, $drive, $file, $snap, $size, $nodename) = @_;
+ $snap = undef if $snap && $snap eq 'current';
+
my $volid = $drive->{file};
#nbd don't support format blockdev, return the fileblockdev
return $file if $volid =~ /^nbd:/;
@@ -273,6 +284,15 @@ my sub generate_backing_chain_blockdev {
return generate_backing_blockdev($storecfg, $snapshots, $deviceid, $drive, $parentid);
}
+sub generate_blockdev_throttle {
+ my ($drive, $blockdev_file) = @_;
+
+ my $drive_id = get_drive_id($drive);
+ #this is the topfilter entry point, use $drive-drive_id as nodename
+ my $blockdev_throttle = { driver => "throttle", 'node-name' => "drive-$drive_id", 'throttle-group' => "throttle-drive-$drive_id", 'file' => $blockdev_file };
+ return $blockdev_throttle;
+}
+
sub generate_drive_blockdev {
my ($storecfg, $drive, $live_restore_name, $size) = @_;
@@ -297,25 +317,178 @@ sub generate_drive_blockdev {
$blockdev_format->{backing} = $backing_chain if $backing_chain;
}
- my $blockdev_live_restore = undef;
#pflash0 don't support throttle-filter
return $blockdev_format if $drive_id eq 'pflash0';
- if ($live_restore_name) {
- die "$drive_id: Proxmox Backup Server backed drive cannot auto-detect the format\n"
- if !$drive->{format};
+ return generate_blockdev_throttle($drive, $blockdev_format) if !$live_restore_name;
- $blockdev_live_restore = { 'node-name' => "liverestore-drive-$drive_id",
- backing => $live_restore_name,
- 'auto-remove' => 'on', format => "alloc-track",
- file => $blockdev_format };
- }
+ die "$drive_id: Proxmox Backup Server backed drive cannot auto-detect the format\n"
+ if !$drive->{format};
- #this is the topfilter entry point, use $drive-drive_id as nodename
- my $blockdev_throttle = { driver => "throttle", 'node-name' => "drive-$drive_id", 'throttle-group' => "throttle-drive-$drive_id" };
#put liverestore filter between throttle && format filter
- $blockdev_throttle->{file} = $live_restore_name ? $blockdev_live_restore : $blockdev_format;
- return $blockdev_throttle,
+ my $blockdev_live_restore = { 'node-name' => "liverestore-drive-$drive_id",
+ backing => $live_restore_name,
+ 'auto-remove' => 'on', format => "alloc-track",
+ file => $blockdev_format };
+
+ return generate_blockdev_throttle($drive, $blockdev_live_restore);
+}
+
+sub blockdev_external_snapshot {
+ my ($storecfg, $vmid, $deviceid, $drive, $snap, $size) = @_;
+
+ my $volid = $drive->{file};
+
+ #preallocate add a new current file with reference to backing-file
+ PVE::Storage::volume_snapshot($storecfg, $volid, $snap, 1);
+
+ #be sure to add drive in write mode
+ delete($drive->{ro});
+
+ my $new_file_blockdev = generate_file_blockdev($storecfg, $drive);
+ my $new_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $new_file_blockdev);
+
+ my $snap_file_blockdev = generate_file_blockdev($storecfg, $drive, $snap);
+ my $snap_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $snap_file_blockdev, $snap);
+
+ #backing need to be forced to undef in blockdev, to avoid reopen of backing-file on blockdev-add
+ $new_fmt_blockdev->{backing} = undef;
+
+ mon_cmd($vmid, 'blockdev-add', %$new_fmt_blockdev);
+
+ mon_cmd($vmid, 'blockdev-snapshot', node => $snap_fmt_blockdev->{'node-name'}, overlay => $new_fmt_blockdev->{'node-name'});
+}
+
+sub blockdev_delete {
+ my ($storecfg, $vmid, $drive, $file_blockdev, $fmt_blockdev, $snap) = @_;
+
+ #add eval as reopen is auto removing the old nodename automatically only if it was created at vm start in command line argument
+ eval { mon_cmd($vmid, 'blockdev-del', 'node-name' => $file_blockdev->{'node-name'}) };
+ eval { mon_cmd($vmid, 'blockdev-del', 'node-name' => $fmt_blockdev->{'node-name'}) };
+
+ #delete the file (don't use vdisk_free as we don't want to delete all snapshot chain)
+ print"delete old $file_blockdev->{filename}\n";
+
+ my $storage_name = PVE::Storage::parse_volume_id($drive->{file});
+
+ my $volid = $drive->{file};
+ PVE::Storage::volume_snapshot_delete($storecfg, $volid, $snap, 1);
}
+sub blockdev_rename {
+ my ($storecfg, $vmid, $deviceid, $drive, $src_snap, $target_snap, $parent_snap) = @_;
+
+ print "rename $src_snap to $target_snap\n";
+
+ my $volid = $drive->{file};
+
+ my $src_file_blockdev = generate_file_blockdev($storecfg, $drive, $src_snap);
+ my $src_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $src_file_blockdev, $src_snap);
+
+ #rename volume image
+ PVE::Storage::rename_volume($storecfg, $volid, $vmid, undef, $src_snap, $target_snap);
+
+ my $target_file_blockdev = generate_file_blockdev($storecfg, $drive, $target_snap);
+ my $target_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $target_file_blockdev, $target_snap);
+
+ if($target_snap eq 'current' || $src_snap eq 'current') {
+ #rename from|to current
+
+ #add backing to target
+ if ($parent_snap) {
+ my $parent_fmt_nodename = encode_nodename('fmt', $volid, $parent_snap);
+ $target_fmt_blockdev->{backing} = $parent_fmt_nodename;
+ }
+ mon_cmd($vmid, 'blockdev-add', %$target_fmt_blockdev);
+
+ #reopen the current throttlefilter nodename with the target fmt nodename
+ my $throttle_blockdev = generate_blockdev_throttle($drive, $target_fmt_blockdev->{'node-name'});
+ mon_cmd($vmid, 'blockdev-reopen', options => [$throttle_blockdev]);
+ } else {
+ rename($src_file_blockdev->{filename}, $target_file_blockdev->{filename});
+
+ #intermediate snapshot
+ mon_cmd($vmid, 'blockdev-add', %$target_fmt_blockdev);
+
+ #reopen the parent node with the new target fmt backing node
+ my $parent_file_blockdev = generate_file_blockdev($storecfg, $drive, $parent_snap);
+ my $parent_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $parent_file_blockdev, $parent_snap);
+ $parent_fmt_blockdev->{backing} = $target_fmt_blockdev->{'node-name'};
+ mon_cmd($vmid, 'blockdev-reopen', options => [$parent_fmt_blockdev]);
+
+ #change backing-file in qcow2 metadatas
+ mon_cmd($vmid, 'change-backing-file', device => $deviceid, 'image-node-name' => $parent_fmt_blockdev->{'node-name'}, 'backing-file' => $target_file_blockdev->{filename});
+ }
+
+ # delete old file|fmt nodes
+ # add eval as reopen is auto removing the old nodename automatically only if it was created at vm start in command line argument
+ eval { mon_cmd($vmid, 'blockdev-del', 'node-name' => $src_file_blockdev->{'node-name'})};
+ eval { mon_cmd($vmid, 'blockdev-del', 'node-name' => $src_fmt_blockdev->{'node-name'})};
+}
+
+sub blockdev_commit {
+ my ($storecfg, $vmid, $deviceid, $drive, $src_snap, $target_snap) = @_;
+
+ my $volid = $drive->{file};
+
+ print "block-commit $src_snap to base:$target_snap\n";
+
+ my $target_file_blockdev = generate_file_blockdev($storecfg, $drive, $target_snap);
+ my $target_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $target_file_blockdev, $target_snap);
+
+ my $src_file_blockdev = generate_file_blockdev($storecfg, $drive, $src_snap);
+ my $src_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $src_file_blockdev, $src_snap);
+
+ my $job_id = "commit-$deviceid";
+ my $jobs = {};
+ my $opts = { 'job-id' => $job_id, device => $deviceid };
+
+ $opts->{'base-node'} = $target_fmt_blockdev->{'node-name'};
+ $opts->{'top-node'} = $src_fmt_blockdev->{'node-name'};
+
+ mon_cmd($vmid, "block-commit", %$opts);
+ $jobs->{$job_id} = {};
+
+ # if we commit the current, the blockjob need to be in 'complete' mode
+ my $complete = $src_snap && $src_snap ne 'current' ? 'auto' : 'complete';
+
+ eval { PVE::QemuServer::qemu_drive_mirror_monitor($vmid, undef, $jobs, $complete, 0, 'commit'); };
+ if ($@) {
+ die "Failed to complete block commit: $@\n";
+ }
+
+ blockdev_delete($storecfg, $vmid, $drive, $src_file_blockdev, $src_fmt_blockdev, $src_snap);
+}
+
+sub blockdev_stream {
+ my ($storecfg, $vmid, $deviceid, $drive, $snap, $parent_snap, $target_snap) = @_;
+
+ my $volid = $drive->{file};
+ $target_snap = undef if $target_snap eq 'current';
+
+ my $parent_file_blockdev = generate_file_blockdev($storecfg, $drive, $parent_snap);
+ my $parent_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $parent_file_blockdev, $parent_snap);
+
+ my $target_file_blockdev = generate_file_blockdev($storecfg, $drive, $target_snap);
+ my $target_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $target_file_blockdev, $target_snap);
+
+ my $snap_file_blockdev = generate_file_blockdev($storecfg, $drive, $snap);
+ my $snap_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $snap_file_blockdev, $snap);
+
+ my $job_id = "stream-$deviceid";
+ my $jobs = {};
+ my $options = { 'job-id' => $job_id, device => $target_fmt_blockdev->{'node-name'} };
+ $options->{'base-node'} = $parent_fmt_blockdev->{'node-name'};
+ $options->{'backing-file'} = $parent_file_blockdev->{filename};
+
+ mon_cmd($vmid, 'block-stream', %$options);
+ $jobs->{$job_id} = {};
+
+ eval { PVE::QemuServer::qemu_drive_mirror_monitor($vmid, undef, $jobs, 'auto', 0, 'stream'); };
+ if ($@) {
+ die "Failed to complete block stream: $@\n";
+ }
+
+ blockdev_delete($storecfg, $vmid, $drive, $snap_file_blockdev, $snap_fmt_blockdev, $snap);
+}
1;
diff --git a/test/snapshot-test.pm b/test/snapshot-test.pm
index f130a5a5..1f61a13f 100644
--- a/test/snapshot-test.pm
+++ b/test/snapshot-test.pm
@@ -362,8 +362,8 @@ sub qmp_cmd {
# BEGIN redefine PVE::QemuServer methods
-sub do_snapshots_with_qemu {
- return 0;
+sub do_snapshots_type {
+ return 'storage';
}
sub vm_start {
--
2.39.5
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