[pve-devel] [PATCH 5/5] DRBD: Implement snapshots.

[Philipp Marek]

---
 PVE/Storage/DRBDPlugin.pm | 88 ++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 84 insertions(+), 4 deletions(-)

diff --git a/PVE/Storage/DRBDPlugin.pm b/PVE/Storage/DRBDPlugin.pm
index 14f232b..3cc7f0b 100644
--- a/PVE/Storage/DRBDPlugin.pm
+++ b/PVE/Storage/DRBDPlugin.pm
@@ -5,6 +5,8 @@ use warnings;
 use IO::File;
 use Net::DBus;
 use Data::Dumper;
+use Digest::SHA;
+use Time::HiRes;
 
 use PVE::Tools qw(run_command trim);
 use PVE::INotify;
@@ -17,6 +19,10 @@ use base qw(PVE::Storage::Plugin);
 
 my $default_redundancy = 2;
 
+# constants to use as DRBDmanage property keys
+our $PN_IS_TEMP_RES = "aux:proxmox:is-temp-resource";
+
+
 sub type {
     return 'drbd';
 }
@@ -298,7 +304,7 @@ sub deactivate_storage {
 sub activate_volume {
     my ($class, $storeid, $scfg, $volname, $snapname, $cache) = @_;
 
-    die "Snapshot not implemented on DRBD\n" if $snapname;
+    return activate_volume_from_snapshot(@_) if $snapname;
 
     my $path = $class->path($scfg, $volname);
     
@@ -340,7 +346,7 @@ sub activate_volume {
 sub deactivate_volume {
     my ($class, $storeid, $scfg, $volname, $snapname, $cache) = @_;
 
-    die "Snapshot not implemented on DRBD\n" if $snapname;
+    return deactivate_volume_from_snapshot(@_) if $snapname;
 
     return undef; # fixme: should we unassign ?
 
@@ -358,6 +364,58 @@ sub deactivate_volume {
     return undef;    
 }
 
+sub activate_volume_from_snapshot {
+    my ($class, $storeid, $scfg, $volname, $snapname, $cache) = @_;
+
+    my $hdl = connect_drbdmanage_service();
+
+# create a new temporary resource, with an optional DRBD client on this node.
+
+# If the snapshot would be activated multiple times, and perhaps even
+# concurrently, we might benefit from a "shared" resource.
+# (That might need to do some reference counting and/or make the DRBD
+# device read-only, to avoid data divergence for multiple accessing nodes
+# that might all try to replay the journals, etc.)
+
+# start with volume- and snapshotname, but get a unique ID.
+    my $new_name = sprintf("%.32s-%.12s",
+		    sprintf("%.24s-%.24s", $volname, $snapname),
+		    Digest::SHA::sha1_base64($volname, $snapname,
+			    $$, Time::HiRes::gettimeofday()));
+
+    my $r_prop = { $PN_IS_TEMP_RES => '1', };
+
+    my ($rc) = $hdl->restore_snapshot($new_name, $volname, $snapname, $r_prop, []);
+    check_drbd_res($rc);
+
+# now get a local assignment...
+    return activate_volume($class, $storeid, $scfg, $new_name, undef, $cache);
+}
+
+sub deactivate_volume_from_snapshot {
+    my ($class, $storeid, $scfg, $volname, $snapname, $cache) = @_;
+
+    my $hdl = connect_drbdmanage_service();
+    my $nodename = PVE::INotify::nodename();
+
+    my ($rc, $res) = $hdl->list_resources([$volname], 0, {}, {});
+    check_drbd_res($rc);
+
+# TODO: should we throw an error if that doesn't exist anymore?
+    warn("Resource '$volname' doesn't exist anymore?"),return undef if !$res;
+    die("Multiple resources with name '$volname'?"),return undef if @$res != 1;
+
+    my $prop = $res->[0][1];
+
+    if ($prop->{$PN_IS_TEMP_RES}) {
+        my ($rc) = $hdl->remove_resource($volname, 0);
+        check_drbd_res($rc);
+    }
+
+
+    return undef;
+}
+
 sub volume_resize {
     my ($class, $scfg, $storeid, $volname, $size, $running) = @_;
 
@@ -374,19 +432,40 @@ sub volume_resize {
 sub volume_snapshot {
     my ($class, $scfg, $storeid, $volname, $snap, $running) = @_;
 
-    die "drbd snapshot is not implemented";
+    my $hdl = connect_drbdmanage_service();
+
+    my ($rc) = $hdl->create_snapshot($volname, $snap, [], {});
+    check_drbd_res($rc);
+    return undef;
 }
 
 sub volume_snapshot_rollback {
     my ($class, $scfg, $storeid, $volname, $snap) = @_;
 
     die "drbd snapshot rollback is not implemented";
+# FIXME: inplace?
+}
+
+sub volume_rollback_is_possible {
+    my ($class, $scfg, $storeid, $volname, $snap) = @_; 
+
+    my $hdl = connect_drbdmanage_service();
+
+# just check for existance, no other restrictions
+    my ($rc) = $hdl->list_snapshots([$volname], [], [$snap], [], {});
+    check_drbd_res($rc);
+
+    return 1;
 }
 
 sub volume_snapshot_delete {
     my ($class, $scfg, $storeid, $volname, $snap) = @_;
 
-    die "drbd snapshot delete is not implemented";
+    my $hdl = connect_drbdmanage_service();
+
+    my ($rc) = $hdl->remove_snapshot($volname, $snap, 0);
+    check_drbd_res($rc);
+    return undef;
 }
 
 sub volume_has_feature {
@@ -394,6 +473,7 @@ sub volume_has_feature {
 
     my $features = {
         copy => { base => 1, current => 1},
+        snapshot => { current => 1, snap => 1}, ## what's the difference?
     };
 
     my ($vtype, $name, $vmid, $basename, $basevmid, $isBase) =
-- 
2.6.1