[pve-devel] [PATCH container v2 5/6] migration: only migrate volumes used by the guest

[Aaron Lauterer]

When scanning all configured storages for volumes belonging to the
container, the migration could easily fail if a storage is not
available, but enabled. That storage might not even be used by the
container at all.

By not doing that and only looking at the disk images referenced in the
config, we can avoid that.
We need to add additional steps for pending volumes with checks if they
actually exist. Changing an existing mountpoint to a new volume
will only create the volume on the next start of the container.

The big change regarding behavior is that volumes not referenced in the
container config will be ignored.  They are already orphans that used to
be migrated as well, but are now left where they are.

Signed-off-by: Aaron Lauterer <a.lauterer at proxmox.com>
---
 src/PVE/LXC/Migrate.pm | 47 +++++++++++++++---------------------------
 1 file changed, 17 insertions(+), 30 deletions(-)

diff --git a/src/PVE/LXC/Migrate.pm b/src/PVE/LXC/Migrate.pm
index ccf5157..8e11be7 100644
--- a/src/PVE/LXC/Migrate.pm
+++ b/src/PVE/LXC/Migrate.pm
@@ -195,6 +195,17 @@ sub phase1 {
 
 	return if !$volid;
 
+	# check if volume exists, might be a pending new one
+	eval {
+	    PVE::Storage::path($self->{storecfg}, $volid);
+	};
+	if ($@ =~ m/^unable to parse/) {
+	    $self->log('info', "volume '$volid' does not exist (pending change?)");
+	    return;
+	} elsif ($@) {
+	    die $@;
+	}
+
 	my ($sid, $volname) = PVE::Storage::parse_volume_id($volid);
 
 	# check if storage is available on source node
@@ -256,42 +267,18 @@ sub phase1 {
 	&$log_error($@, $volid) if $@;
     };
 
-    # first unused / lost volumes owned by this container
-    my @sids = PVE::Storage::storage_ids($self->{storecfg});
-    foreach my $storeid (@sids) {
-	my $scfg = PVE::Storage::storage_config($self->{storecfg}, $storeid);
-	next if $scfg->{shared} && !$remote;
-	next if !PVE::Storage::storage_check_enabled($self->{storecfg}, $storeid, undef, 1);
-
-	# get list from PVE::Storage (for unreferenced volumes)
-	my $dl = PVE::Storage::vdisk_list($self->{storecfg}, $storeid, $vmid, undef, 'rootdir');
-
-	next if @{$dl->{$storeid}} == 0;
-
-	# check if storage is available on target node
-	my $targetsid = PVE::JSONSchema::map_id($self->{opts}->{storagemap}, $storeid);
-	if (!$remote) {
-	    my $target_scfg = PVE::Storage::storage_check_enabled($self->{storecfg}, $targetsid, $self->{node});
-
-	    die "content type 'rootdir' is not available on storage '$targetsid'\n"
-		if !$target_scfg->{content}->{rootdir};
-	}
-
-	PVE::Storage::foreach_volid($dl, sub {
-	    my ($volid, $sid, $volname) = @_;
-
-	    $volhash->{$volid}->{ref} = 'storage';
-	    $volhash->{$volid}->{targetsid} = $targetsid;
-	});
-    }
-
-    # then all volumes referenced in snapshots
+    # first all volumes referenced in snapshots
     foreach my $snapname (keys %{$conf->{snapshots}}) {
 	&$test_volid($conf->{snapshots}->{$snapname}->{'vmstate'}, 0, undef)
 	    if defined($conf->{snapshots}->{$snapname}->{'vmstate'});
 	PVE::LXC::Config->foreach_volume($conf->{snapshots}->{$snapname}, $test_mp, $snapname);
     }
 
+    # then all pending volumes
+    if (defined $conf->{pending} && %{$conf->{pending}}) {
+	PVE::LXC::Config->foreach_volume($conf->{pending}, $test_mp);
+    }
+
     # finally all current volumes
     PVE::LXC::Config->foreach_volume_full($conf, { include_unused => 1 }, $test_mp);
 
-- 
2.30.2