[pve-devel] [PATCH v3 qemu-server 11/11] qcow2: add external snapshot support

[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 qemu-server 11/11] qcow2: add external snapshot support
Date: Mon, 16 Dec 2024 10:12:29 +0100
Message-ID: <20241216091229.3142660-16-alexandre.derumier@groupe-cyllene.com>

Signed-off-by: Alexandre Derumier <alexandre.derumier@groupe-cyllene.com>
---
 PVE/QemuConfig.pm |   4 +-
 PVE/QemuServer.pm | 345 ++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 335 insertions(+), 14 deletions(-)

diff --git a/PVE/QemuConfig.pm b/PVE/QemuConfig.pm
index ffdf9f03..c17edb46 100644
--- a/PVE/QemuConfig.pm
+++ b/PVE/QemuConfig.pm
@@ -375,7 +375,7 @@ 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 {
@@ -412,7 +412,7 @@ 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 3a3feadf..f29a8449 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -4959,20 +4959,269 @@ 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, $deviceid)) {
-	mon_cmd($vmid, 'blockdev-snapshot-internal-sync', device => $deviceid, name => $snap);
+    my $do_snapshots_with_qemu = do_snapshots_with_qemu($storecfg, $volid, $deviceid) if $running;
+    if ($do_snapshots_with_qemu) {
+	if($do_snapshots_with_qemu == 2) {
+	    my $snap_path = PVE::Storage::path($storecfg, $volid, $snap);
+	    my $path = PVE::Storage::path($storecfg, $volid);
+	    blockdev_current_rename($storecfg, $vmid, $deviceid, $drive, $path, $snap_path, 1);
+	    blockdev_external_snapshot($storecfg, $vmid, $deviceid, $drive, $snap);
+	} else {
+	    mon_cmd($vmid, 'blockdev-snapshot-internal-sync', device => $deviceid, name => $snap);
+	}
     } else {
 	PVE::Storage::volume_snapshot($storecfg, $volid, $snap);
     }
 }
 
+sub blockdev_external_snapshot {
+    my ($storecfg, $vmid, $deviceid, $drive, $snap) = @_;
+
+    my $nodes = get_blockdev_nodes($vmid);
+    my $volid = $drive->{file};
+    my $path = PVE::Storage::path($storecfg, $volid, $snap);
+    my $format_node = find_blockdev_node($nodes, $path, 'fmt');
+    my $format_nodename = $format_node->{'node-name'};
+
+    #preallocate add a new current file
+    my $new_current_fmt_nodename = get_blockdev_nextid("fmt-$deviceid", $nodes);
+    my $new_current_file_nodename = get_blockdev_nextid("file-$deviceid", $nodes);
+    PVE::Storage::volume_snapshot($storecfg, $volid, $snap);
+    my $new_file_blockdev = generate_file_blockdev($storecfg, $drive, $new_current_file_nodename);
+    my $new_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $new_current_fmt_nodename, $new_file_blockdev);
+
+    $new_fmt_blockdev->{backing} = undef;
+    PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-add', %$new_fmt_blockdev);
+    mon_cmd($vmid, 'blockdev-snapshot', node => $format_nodename, overlay => $new_current_fmt_nodename);
+}
+
+sub blockdev_snap_rename {
+    my ($storecfg, $vmid, $deviceid, $drive, $src_path, $target_path) = @_;
+
+    my $nodes = get_blockdev_nodes($vmid);
+    my $volid = $drive->{file};
+
+    #copy the original drive param and change target file
+    my $target_fmt_nodename = get_blockdev_nextid("fmt-$deviceid", $nodes);
+    my $target_file_nodename = get_blockdev_nextid("file-$deviceid", $nodes);
+
+    my $src_fmt_node = find_blockdev_node($nodes, $src_path, 'fmt');
+    my $src_fmt_nodename = $src_fmt_node->{'node-name'};
+    my $src_file_node = find_blockdev_node($nodes, $src_path, 'file');
+    my $src_file_nodename = $src_file_node->{'node-name'};
+
+    #untaint
+    if ($src_path =~ m/^(\S+)$/) {
+	$src_path = $1;
+    }
+    if ($target_path =~ m/^(\S+)$/) {
+	$target_path = $1;
+    }
+
+    #create a hardlink
+    link($src_path, $target_path);
+
+    #add new format blockdev
+    my $read_only = 1;
+    my $target_file_blockdev = generate_file_blockdev($storecfg, $drive, $target_file_nodename);
+    $target_file_blockdev->{filename} = $target_path;
+    my $target_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $target_fmt_nodename, $target_file_blockdev, $read_only);
+
+    PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-add', %$target_fmt_blockdev);
+
+    #reopen the parent node with different backing file
+    my $parent_fmt_node = find_parent_node($nodes, $src_path);
+    my $parent_fmt_nodename = $parent_fmt_node->{'node-name'};
+    my $parent_path = $parent_fmt_node->{file};
+    my $parent_file_node = find_blockdev_node($nodes, $parent_path, 'file');
+    my $parent_file_nodename = $parent_file_node->{'node-name'};
+    my $filenode_exist = 1;
+    $read_only = $parent_fmt_node->{ro};
+    my $parent_fmt_blockdev = generate_format_blockdev($storecfg, $drive, $parent_fmt_nodename, $parent_file_nodename, $read_only);
+    $parent_fmt_blockdev->{backing} = $target_fmt_nodename;
+    PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-reopen', options => [$parent_fmt_blockdev]);
+
+    #change backing-file in qcow2 metadatas
+    PVE::QemuServer::Monitor::mon_cmd($vmid, 'change-backing-file', device => $deviceid, 'image-node-name' => $parent_fmt_nodename, 'backing-file' => $target_path);
+
+    # fileblockdev seem to be autoremoved, if it have been created online, but not if they are created at start with command line
+    eval { PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-del', 'node-name' => $src_file_nodename) };
+    eval { PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-del', 'node-name' => $src_fmt_nodename) };
+
+    #delete old $path link
+    unlink($src_path);
+
+    #rename underlay
+    my $storage_name = PVE::Storage::parse_volume_id($volid);
+    my $scfg = $storecfg->{ids}->{$storage_name};
+    if ($scfg->{type} eq 'lvm') {
+	print"lvrename $src_path to $target_path\n";
+	run_command(
+	    ['/sbin/lvrename', $src_path, $target_path],
+	    errmsg => "lvrename $src_path to $target_path error",
+	);
+    }
+}
+
+sub blockdev_current_rename {
+    my ($storecfg, $vmid, $deviceid, $drive, $path, $target_path, $skip_underlay) = @_;
+    ## rename current running image
+
+    my $nodes = get_blockdev_nodes($vmid);
+    my $volid = $drive->{file};
+    my $target_file_nodename = get_blockdev_nextid("file-$deviceid", $nodes);
+
+    my $file_blockdev = generate_file_blockdev($storecfg, $drive, $target_file_nodename);
+    $file_blockdev->{filename} = $target_path;
+
+    my $format_node = find_blockdev_node($nodes, $path, 'fmt');
+    my $format_nodename = $format_node->{'node-name'};
+
+    my $file_node = find_blockdev_node($nodes, $path, 'file');
+    my $file_nodename = $file_node->{'node-name'};
+
+    my $backingfile = $format_node->{image}->{'backing-filename'};
+    my $backing_node = $backingfile ? find_blockdev_node($nodes, $backingfile, 'fmt') : undef;
+
+    #create a hardlink
+    link($path, $target_path);
+    #add new file blockdev
+    PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-add', %$file_blockdev);
+
+    #reopen the current fmt nodename with a new file nodename
+    my $reopen_blockdev = generate_format_blockdev($storecfg, $drive, $format_nodename, $target_file_nodename);
+    $reopen_blockdev->{backing} = $backing_node->{'node-name'};
+    PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-reopen', options => [$reopen_blockdev]);
+
+    # delete old file blockdev
+    # seem that the old file block is autoremoved after reopen if the file nodename is autogenerad with #block ?
+    eval { PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-del', 'node-name' => $file_nodename) };
+
+    unlink($path);
+
+    #skip_underlay: lvm will be renamed later in Storage::volume_snaphot
+    return if $skip_underlay;
+
+    #rename underlay
+    my $storage_name = PVE::Storage::parse_volume_id($volid);
+    my $scfg = $storecfg->{ids}->{$storage_name};
+    if ($scfg->{type} eq 'lvm') {
+	print"lvrename $path to $target_path\n";
+	run_command(
+	    ['/sbin/lvrename', $path, $target_path],
+	    errmsg => "lvrename $path to $target_path error",
+	);
+    }
+}
+
+sub blockdev_commit {
+    my ($storecfg, $vmid, $deviceid, $drive, $top_path, $base_path) = @_;
+
+    my $nodes = get_blockdev_nodes($vmid);
+    my $volid = $drive->{file};
+
+    #untaint
+    if ($top_path =~ m/^(\S+)$/) {
+	$top_path = $1;
+    }
+
+    print "block-commit top:$top_path to base:$base_path\n";
+    my $job_id = "commit-$deviceid";
+    my $jobs = {};
+
+    my $base_node = find_blockdev_node($nodes, $base_path, 'fmt');
+    my $top_node = find_blockdev_node($nodes, $top_path, 'fmt');
+
+    my $options = { 'job-id' => $job_id, device => $deviceid };
+    $options->{'top-node'} = $top_node->{'node-name'};
+    $options->{'base-node'} = $base_node->{'node-name'};
+
+
+    mon_cmd($vmid, 'block-commit', %$options);
+    $jobs->{$job_id} = {};
+
+    qemu_drive_mirror_monitor($vmid, undef, $jobs, 'auto', 0, 'commit');
+
+    #remove fmt-blockdev, file-blockdev && file
+    my $fmt_node = find_blockdev_node($nodes, $top_path, 'fmt');
+    my $fmt_nodename = $fmt_node->{'node-name'};
+    eval { PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-del', 'node-name' => $fmt_nodename) };
+
+    my $file_node = find_blockdev_node($nodes, $top_path, 'file');
+    my $file_nodename = $file_node->{'node-name'};
+    eval { PVE::QemuServer::Monitor::mon_cmd($vmid, 'blockdev-del', 'node-name' => $file_nodename) };
+
+
+
+    my $storage_name = PVE::Storage::parse_volume_id($volid);
+    my $scfg = $storecfg->{ids}->{$storage_name};
+    if ($scfg->{type} eq 'lvm') {
+	print"lvremove $top_path\n";
+	run_command(
+	    ['/sbin/lvremove', '-f', $top_path],
+	    errmsg => "lvremove $top_path",
+	);
+    } else {
+	unlink($top_path);
+    }
+
+}
+
+sub blockdev_live_commit {
+    my ($storecfg, $vmid, $deviceid, $drive, $current_path, $snapshot_path) = @_;
+
+    my $nodes = get_blockdev_nodes($vmid);
+    my $volid = $drive->{file};
+
+    #untaint
+    if ($current_path =~ m/^(\S+)$/) {
+	$current_path = $1;
+    }
+
+    print "live block-commit top:$current_path to base:$snapshot_path\n";
+    my $job_id = "commit-$deviceid";
+    my $jobs = {};
+
+    my $snapshot_node = find_blockdev_node($nodes, $snapshot_path, 'fmt');
+    my $snapshot_file_node = find_blockdev_node($nodes, $current_path, 'file');
+    my $current_node = find_blockdev_node($nodes, $current_path, 'fmt');
+
+    my $opts = { 'job-id' => $job_id,
+		  device => $deviceid,
+		  'base-node' => $snapshot_node->{'node-name'},
+		  replaces => $current_node->{'node-name'}
+    };
+    mon_cmd($vmid, "block-commit", %$opts);
+    $jobs->{$job_id} = {};
+
+    qemu_drive_mirror_monitor ($vmid, undef, $jobs, 'complete', 0, 'commit');
+
+    eval { mon_cmd($vmid, 'blockdev-del', 'node-name' => $current_node->{'node-name'}) };
+
+    my $storage_name = PVE::Storage::parse_volume_id($volid);
+    my $scfg = $storecfg->{ids}->{$storage_name};
+    if ($scfg->{type} eq 'lvm') {
+	print"lvremove $current_path\n";
+	run_command(
+	    ['/sbin/lvremove', '-f', $current_path],
+	    errmsg => "lvremove $current_path",
+	);
+    } else {
+	unlink($current_path);
+    }
+
+    return;
+
+}
+
 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;
 
@@ -4984,13 +5233,51 @@ sub qemu_volume_snapshot_delete {
 	});
     }
 
-    if ($attached_deviceid && do_snapshots_with_qemu($storecfg, $volid, $attached_deviceid)) {
-	mon_cmd(
-	    $vmid,
-	    'blockdev-snapshot-delete-internal-sync',
-	    device => $attached_deviceid,
-	    name => $snap,
-	);
+    my $do_snapshots_with_qemu = do_snapshots_with_qemu($storecfg, $volid, $attached_deviceid) if $running;
+    if ($attached_deviceid && $do_snapshots_with_qemu) {
+
+	if ($do_snapshots_with_qemu == 2) {
+
+	    my $path = PVE::Storage::path($storecfg, $volid);
+	    my $snapshots = PVE::Storage::volume_snapshot_info($storecfg, $volid);
+
+	    my $snappath = $snapshots->{$snap}->{file};
+	    return if !-e $snappath;  #already deleted ?
+
+	    my $parentsnap = $snapshots->{$snap}->{parent};
+	    my $childsnap = $snapshots->{$snap}->{child};
+
+	    my $parentpath = $snapshots->{$parentsnap}->{file} if $parentsnap;
+	    my $childpath = $snapshots->{$childsnap}->{file} if $childsnap;
+
+	    #if first snapshot
+	    if(!$parentsnap) {
+		print"delete first snapshot $childpath\n";
+		if($childpath eq $path) {
+		    #if child is the current (last snapshot), we need to a live active-commit
+		    print"commit first snapshot $snappath to current $path\n";
+		    blockdev_live_commit($storecfg, $vmid, $attached_deviceid, $drive, $childpath, $snappath);
+		    print" rename $snappath to $path\n";
+		    blockdev_current_rename($storecfg, $vmid, $attached_deviceid, $drive, $snappath, $path);
+		} else {
+		    print"commit first snapshot $snappath to $childpath path\n";
+		    blockdev_commit($storecfg, $vmid, $attached_deviceid, $drive, $childpath, $snappath);
+		    print" rename $snappath to $childpath\n";
+		    blockdev_snap_rename($storecfg, $vmid, $attached_deviceid, $drive, $snappath, $childpath);
+		}
+	    } else {
+		#intermediate snapshot, we just need to commit the snapshot
+		print"commit intermediate snapshot $snappath to $parentpath\n";
+		blockdev_commit($storecfg, $vmid, $attached_deviceid, $drive, $snappath, $parentpath, 'auto');
+	    }
+	} else {
+	    mon_cmd(
+	        $vmid,
+		'blockdev-snapshot-delete-internal-sync',
+		device => $attached_deviceid,
+		name => $snap,
+	    );
+	}
     } else {
 	PVE::Storage::volume_snapshot_delete(
 	    $storecfg, $volid, $snap, $attached_deviceid ? 1 : undef);
@@ -8066,6 +8353,8 @@ sub do_snapshots_with_qemu {
 	return 1;
     }
 
+    return 2 if $scfg->{snapext} || $scfg->{type} eq 'lvm' && $volid =~ m/\.(qcow2)/;
+
     if ($volid =~ m/\.(qcow2|qed)$/){
 	return 1;
     }
@@ -9169,6 +9458,38 @@ sub delete_ifaces_ipams_ips {
     }
 }
 
+sub find_blockdev_node {
+    my ($nodes, $path, $type) = @_;
+
+    my $found_nodeid = undef;
+    my $found_node = undef;
+    for my $nodeid (keys %$nodes) {
+	my $node = $nodes->{$nodeid};
+	if ($nodeid =~ m/^$type-(\S+)$/ && $node->{file} eq $path ) {
+	    $found_node = $node;
+	    last;
+	}
+    }
+    die "can't found nodeid for file $path\n" if !$found_node;
+    return $found_node;
+}
+
+sub find_parent_node {
+    my ($nodes, $backing_path) = @_;
+
+    my $found_nodeid = undef;
+    my $found_node = undef;
+    for my $nodeid (keys %$nodes) {
+	my $node = $nodes->{$nodeid};
+	if ($nodeid =~ m/^fmt-(\S+)$/ && $node->{backing_file} && $node->{backing_file} eq $backing_path) {
+	    $found_node = $node;
+	    last;
+	}
+    }
+    die "can't found nodeid for file $backing_path\n" if !$found_node;
+    return $found_node;
+}
+
 sub find_fmt_nodename_drive {
     my ($storecfg, $vmid, $drive, $nodes) = @_;
 
-- 
2.39.5



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