[pve-devel] [PATCH v4 qemu-server 2/2] vmconfig_apply_pending: remove redundant write/load config calls

[Oguz Bektas]

since we handle errors gracefully now, we don't need to write & save
config every time we change a setting.

note: this results in a change of behavior in the API. since errors are
handled gracefully instead of "die"ing, when there is a pending change
which cannot be applied for some reason, it will get logged in the
tasklog but the vm will continue booting regardless. the non-applied
change will stay in the pending section of the configuration.

Signed-off-by: Oguz Bektas <o.bektas at proxmox.com>
---

v3 -> v4:
* add explanation in commit message about behavior change in API

 PVE/QemuServer.pm | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 2de8376..9c86bee 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -4993,19 +4993,11 @@ sub vmconfig_apply_pending {
 	my $force = $pending_delete_hash->{$opt}->{force};
 	eval {
 	    die "internal error" if $opt =~ m/^unused/;
-	    $conf = PVE::QemuConfig->load_config($vmid); # update/reload
 	    if (!defined($conf->{$opt})) {
 		PVE::QemuConfig->remove_from_pending_delete($conf, $opt);
-		PVE::QemuConfig->write_config($vmid, $conf);
 	    } elsif (is_valid_drivename($opt)) {
 		vmconfig_delete_or_detach_drive($vmid, $storecfg, $conf, $opt, $force);
 		PVE::QemuConfig->remove_from_pending_delete($conf, $opt);
-		delete $conf->{$opt};
-		PVE::QemuConfig->write_config($vmid, $conf);
-	    } else {
-		PVE::QemuConfig->remove_from_pending_delete($conf, $opt);
-		delete $conf->{$opt};
-		PVE::QemuConfig->write_config($vmid, $conf);
 	    }
 	};
 	if (my $err = $@) {
@@ -5013,24 +5005,20 @@ sub vmconfig_apply_pending {
 	} else {
 	    PVE::QemuConfig->remove_from_pending_delete($conf, $opt);
 	    delete $conf->{$opt};
-	    PVE::QemuConfig->write_config($vmid, $conf);
 	}
+
     }
 
     $conf = PVE::QemuConfig->load_config($vmid); # update/reload
 
     foreach my $opt (keys %{$conf->{pending}}) { # add/change
-	$conf = PVE::QemuConfig->load_config($vmid); # update/reload
-
+	next if $opt eq 'delete'; # just to be sure
 	eval {
 	    if (defined($conf->{$opt}) && ($conf->{$opt} eq $conf->{pending}->{$opt})) {
 		# skip if nothing changed
 	    } elsif (is_valid_drivename($opt)) {
 		vmconfig_register_unused_drive($storecfg, $vmid, $conf, parse_drive($opt, $conf->{$opt}))
 		    if defined($conf->{$opt});
-		$conf->{$opt} = $conf->{pending}->{$opt};
-	    } else {
-		$conf->{$opt} = $conf->{pending}->{$opt};
 	    }
 	};
 	if (my $err = $@) {
@@ -5039,9 +5027,10 @@ sub vmconfig_apply_pending {
 	    $conf->{$opt} = delete $conf->{pending}->{$opt};
 	    PVE::QemuConfig->cleanup_pending($conf);
 	}
-
-	PVE::QemuConfig->write_config($vmid, $conf);
     }
+
+    # write all changes at once to avoid unnecessary i/o
+    PVE::QemuConfig->write_config($vmid, $conf);
 }
 
 my $safe_num_ne = sub {
-- 
2.20.1