[pve-devel] [PATCH v2 qemu-server 1/1] implement external 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 v2 qemu-server 1/1] implement external snapshot
Date: Mon, 30 Sep 2024 13:31:52 +0200
Message-ID: <20240930113153.2896648-3-alexandre.derumier@groupe-cyllene.com>

Signed-off-by: Alexandre Derumier <alexandre.derumier@groupe-cyllene.com>
---
 PVE/QemuServer.pm | 108 ++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 95 insertions(+), 13 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index b26da505..1523df15 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -1549,7 +1549,11 @@ sub print_drive_commandline_full {
     } else {
 	if ($storeid) {
 	    $path = PVE::Storage::path($storecfg, $volid);
-	    $format //= qemu_img_format($scfg, $volname);
+	    if ($scfg->{snapext}) {
+		$format //= qemu_img_format($scfg, $path);
+	    } else {
+		$format //= qemu_img_format($scfg, $volname);
+	    }
 	} else {
 	    $path = $volid;
 	    $format //= "raw";
@@ -4713,9 +4717,31 @@ sub qemu_volume_snapshot {
     my ($vmid, $deviceid, $storecfg, $volid, $snap) = @_;
 
     my $running = check_running($vmid);
+    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 $snapshot_file = PVE::Storage::path($storecfg, $volid, $snap);
+	    #allocate volume is external snapshot is a block device
+	    my $snap_volid = undef;
+	    if ($snapshot_file =~ m|^/dev/.+|) {
+ 		my ($storeid, $volname) = PVE::Storage::parse_volume_id($volid, 1);
+		my $size = PVE::Storage::volume_size_info($storecfg, $volid, 5);
+		#add 100M for qcow2 headers
+		$size = int($size/1024) + (100*1024);
+		my $snap_volname = $volname."-snap-$snap";
+		$snap_volid = PVE::Storage::vdisk_alloc($storecfg, $storeid, $vmid, 'raw', $snap_volname, $size);
+		PVE::Storage::activate_volumes($storecfg, [$snap_volid]);
+	    }
+
+	    eval { mon_cmd($vmid, 'blockdev-snapshot-sync', device => $deviceid, 'snapshot-file' => $snapshot_file, format => 'qcow2') };
 
-    if ($running && do_snapshots_with_qemu($storecfg, $volid, $deviceid)) {
-	mon_cmd($vmid, 'blockdev-snapshot-internal-sync', device => $deviceid, name => $snap);
+	    if ($@) {
+		PVE::Storage::vdisk_free($storecfg, $snap_volid) if $snapshot_file =~ m|^/dev/.+|;
+		die $@;
+	    }
+	} else {
+	    mon_cmd($vmid, 'blockdev-snapshot-internal-sync', device => $deviceid, name => $snap);
+	}
     } else {
 	PVE::Storage::volume_snapshot($storecfg, $volid, $snap);
     }
@@ -4735,13 +4761,52 @@ 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 $snapshots = PVE::Storage::volume_snapshot_info($storecfg, $volid);
+
+	    my $currentpath = $snapshots->{current}->{file};
+	    my $snappath = $snapshots->{$snap}->{file};
+	    my $snapvolid = $snapshots->{$snap}->{volid};
+	    return if !$snappath;  #already delete
+
+	    my $parentsnap = $snapshots->{$snap}->{parent};
+	    die "error: we can't find a parent for this snapshot" if !$parentsnap;
+
+	    my $parentpath = $snapshots->{$parentsnap}->{file};
+	    my $parentformat = $snapshots->{$parentsnap}->{'format'} if $parentsnap;
+
+	    print "block-commit  top:$snappath base:$parentpath\n";
+
+            my $job_id = "commit-$attached_deviceid";
+	    my $jobs = {};
+	    mon_cmd(
+	        $vmid,
+		'block-commit',
+		'job-id' => $job_id,
+		device => $attached_deviceid,
+		top => $snappath,
+		base => $parentpath,
+	    );
+	    $jobs->{$job_id} = {};
+
+	    #if we delete the current, block-job-complete to finish
+	    my $completion = $currentpath eq $snappath ? 'complete' : 'auto';
+	    qemu_drive_mirror_monitor($vmid, undef, $jobs, $completion, 0, 'commit');
+	    #fixme. delete the disks when all jobs are ok ?
+	    #delete the lvm volume
+	    PVE::Storage::vdisk_free($storecfg, $snapvolid);
+	} 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);
@@ -7776,6 +7841,8 @@ sub do_snapshots_with_qemu {
 	return 1;
     }
 
+    return 2 if $scfg->{snapext};
+
     if ($volid =~ m/\.(qcow2|qed)$/){
 	return 1;
     }
@@ -7849,8 +7916,23 @@ sub qemu_img_convert {
     if ($src_storeid) {
 	PVE::Storage::activate_volumes($storecfg, [$src_volid], $snapname);
 	my $src_scfg = PVE::Storage::storage_config($storecfg, $src_storeid);
-	$src_format = qemu_img_format($src_scfg, $src_volname);
-	$src_path = PVE::Storage::path($storecfg, $src_volid, $snapname);
+	if($src_scfg->{snapext}) {
+	    my $snapshots = PVE::Storage::volume_snapshot_info($storecfg, $src_volid);
+	    $snapname = 'current' if !$snapname;
+	    #if we don't clone the current image
+	    #need to use the parent if available, as it's the readonly image view
+	    #at the time of the snapshot
+	    my $parentsnap = $snapshots->{$snapname}->{parent};
+	    $snapname = $parentsnap if($parentsnap && $snapname ne 'current');
+	    $src_format = $snapshots->{$snapname}->{format};
+	    $src_path = $snapshots->{$snapname}->{file};
+	    $src_volid = $snapshots->{$snapname}->{volid};
+	    $snapname = undef;
+	    PVE::Storage::activate_volumes($storecfg, [$src_volid], $snapname);
+	} else {
+	    $src_format = qemu_img_format($src_scfg, $src_volname);
+	    $src_path = PVE::Storage::path($storecfg, $src_volid, $snapname);
+	}
 	$src_is_iscsi = ($src_path =~ m|^iscsi://|);
 	$cachemode = 'none' if $src_scfg->{type} eq 'zfspool';
     } elsif (-f $src_volid || -b $src_volid) {
@@ -7920,7 +8002,7 @@ sub qemu_img_format {
 
     # FIXME: this entire function is kind of weird given that `parse_volname`
     # also already gives us a format?
-    my $is_path_storage = $scfg->{path} || $scfg->{type} eq 'esxi';
+    my $is_path_storage = $scfg->{path} || $scfg->{type} eq 'esxi' || $scfg->{snapext};
 
     if ($is_path_storage && $volname =~ m/\.($PVE::QemuServer::Drive::QEMU_FORMAT_RE)$/) {
 	return $1;
-- 
2.39.2



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