BTRFS subvolumes

[Frank Steinberg]

Hi,

I intend to switch my FAI setups from using ext4 to btrfs, with no RAID levels („single“), but with subvolumes (on a common toplevel volume). With the current setup-storage code, I could not get this working. The main reason is that each volume under the btrfs config section causes a new mkfs.btrfs command, so that subsequent volumes cause unneeded mkfs calls which also override previously created subvolumes.

I am not very familiar with the setup-storage code and its concepts and I am not at all a perl programmer, however the following patch seems to solve my problem as a quick workaround. Maybe it could be useful to others, and maybe it could give Thomas an idea to improve his code.

 -frank


--- Commands.pm	2016-07-01 17:31:38.000000000 +0200
+++ Commands.pm.ibr	2016-10-06 10:29:51.462135735 +0200
@@ -354,11 +354,24 @@
     }
     # creates the BTRFS volume/RAID
     if ($raidlevel eq 'single') {
-          &FAI::push_command("mkfs.btrfs -d single $createopts ". join(" ", at devs),
+	my $first = 1;
+	my $c = "mkfs.btrfs -d single $createopts ".join(" ", at devs);
+	my $ii = 1; while ($ii < $FAI::n_c_i) {
+	  if ($FAI::commands{$ii}{cmd} eq $c) {
+	    $first = 0;
+	  }
+	  $ii++;
+	}
+	if ($first == 0) {
+          &FAI::push_command("true",
                              "$pre_req",
                              "btrfs_built_raid_$id");
-
         } else {
+          &FAI::push_command("mkfs.btrfs -d single $createopts ". join(" ", at devs),
+                             "$pre_req",
+                             "btrfs_built_raid_$id");
+	}
+      } else {
           &FAI::push_command("mkfs.btrfs -d raid$raidlevel $createopts ". join(" ", at devs),
                              "$pre_req",
                              "btrfs_built_raid_$id“);