Fix for when snapshots are present

The method used has also changed to use zpool list then zfs list on individual
filesystems. This is because zfs list can be very slow if there are a lot
of filesystems present.

git-svn-id: https://labs.omniti.com/resmon/branches/resmon2@338 8c0face9-b7db-6ec6-c4b3-d5f7145c7d55

lib/Core/ZpoolFree.pm

@@ -35,6 +35,10 @@ where zpool list does not report the true usable free space (e.g. raidz
 pools). See http://www.cuddletech.com/blog/pivot/entry.php?id=1013 for another
 case where zpool list does not report the correct values for monitoring.
 
+Zpool list is still used to get the list of pools on the system, and then zfs
+list is run individually for each pool. This is done to improve performance in
+the case where there are many filesystems.
+
 =head1 CONFIGURATION
 
 =over
@@ -47,6 +51,10 @@ The check name is descriptive only in this check. It is not used for anything.
 
 Specify an alternative location for the zfs command. Default: /sbin/zfs.
 
+=item zpool_path
+
+Specify an alternative location for the zpool command. Default: /sbin/zpool.
+
 =back
 
 =head1 METRICS
@@ -90,13 +98,19 @@ sub handler {
     my $self = shift;
     my $config = $self->{config}; # All configuration is in here
     my $zfs_command = $config->{zfs_command} || "/sbin/zfs";
+    my $zpool_command = $config->{zpool_command} || "/sbin/zpool";
     my $status = {};
-    my $output = run_command("$zfs_command list -H -o name,used,avail");
-    foreach my $line (split /\n/, $output) {
-        my ($name, $used, $uunit, $free, $funit) = $line =~
+    my $output = run_command("$zpool_command list -H -o name");
+    foreach my $pool (split /\n/, $output) {
+        # Sanity check in case zpool outputs something strange
+        die "Invalid pool name: $pool" if $pool !~ /[a-zA-Z0-9_.-]+/;
+        my $zfs_output = run_command(
+            "$zfs_command list -H -o name,used,avail $pool");
+        my ($name, $used, $uunit, $free, $funit) = $zfs_output =~
             /(\S+)\s+([0-9.]+)([BKMGTPEZ]?)\s+([0-9.]+)([BKMGTPEZ]?)/;
         # Make sure we were able to match the regex
-        die "Unable to parse zfs command output: $line\n" unless defined($name);
+        die "Unable to parse zfs command output: $zfs_output\n"
+            unless defined($name);
         next if ($name =~ /\//); # We're only interested in the root of a pool
 
         # Convert human readable units to bytes