[pve-devel] [PATCH storage 1/3] rbd: use 'rbd ls' without '-l' to find free names

[Fabian Grünbichler]

with more than a few images, 'rbd ls -l' gets rather slow
compared to a simple 'rbd ls'. since we only need to check
existing image names for finding a free one, the latter is
sufficient.

example with ~400 rbd images:
$ time rbd ls -p ceph-vm > /dev/null
real    0m0.027s
user    0m0.012s
sys     0m0.008s

$ time rbd ls -l -p ceph-vm > /dev/null
real    0m5.250s
user    0m1.632s
sys     0m0.584s

a linked clone of two disks on the same setup accordingly
also shows a massive speedup:

$ time qm clone 1000 10000 -snap test
create linked clone of drive scsi0 (ceph-vm:vm-1000-disk-2)
clone vm-1000-disk-2: vm-1000-disk-2 snapname test to
vm-10000-disk-1
create linked clone of drive scsi1 (ceph-vm:vm-1000-disk-1)
clone vm-1000-disk-1: vm-1000-disk-1 snapname test to
vm-10000-disk-2

real    0m11.157s
user    0m3.752s
sys     0m1.308s

$ time qm clone 1000 10000 -snap test
create linked clone of drive scsi1 (ceph-vm:vm-1000-disk-1)
clone vm-1000-disk-1: vm-1000-disk-1 snapname test to
vm-10000-disk-1
create linked clone of drive scsi0 (ceph-vm:vm-1000-disk-2)
clone vm-1000-disk-2: vm-1000-disk-2 snapname test to
vm-10000-disk-2

real    0m0.872s
user    0m0.652s
sys     0m0.096s

Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
---
 PVE/Storage/RBDPlugin.pm | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/PVE/Storage/RBDPlugin.pm b/PVE/Storage/RBDPlugin.pm
index 989a85e..b44b9ba 100644
--- a/PVE/Storage/RBDPlugin.pm
+++ b/PVE/Storage/RBDPlugin.pm
@@ -338,17 +338,24 @@ sub path {
 my $find_free_diskname = sub {
     my ($storeid, $scfg, $vmid) = @_;
 
-    my $rbd = rbd_ls($scfg, $storeid);
-    my $pool =  $scfg->{pool} ? $scfg->{pool} : 'rbd';
+    my $cmd = &$rbd_cmd($scfg, $storeid, 'ls');
     my $disk_ids = {};
-    my $dat = $rbd->{$pool};
 
-    foreach my $image (keys %$dat) {
-	my $volname = $dat->{$image}->{name};
-	if ($volname =~ m/(vm|base)-$vmid-disk-(\d+)/){
+    my $parser = sub {
+	my $line = shift;
+
+	if ($line =~  m/^(vm|base)-\Q$vmid\E+-disk-(\d+)$/) {
 	    $disk_ids->{$2} = 1;
 	}
-    }
+    };
+
+    eval {
+	run_rbd_command($cmd, errmsg => "rbd error", errfunc => sub {}, outfunc => $parser);
+    };
+    my $err = $@;
+
+    die $err if $err && $err !~ m/doesn't contain rbd images/;
+
     #fix: can we search in $rbd hash key with a regex to find (vm|base) ?
     for (my $i = 1; $i < 100; $i++) {
         if (!$disk_ids->{$i}) {
-- 
2.1.4