[pve-devel] [PATCH v2 container] Improve error handling in snapshot_create

[Fabian Grünbichler]

Set unfreeze before trying to freeze, otherwise an aborted
or failed lxc-freeze will not be reversed by our error
handling, leaving the container in a (partially) frozen
state.

Combine existing code from snapshot_commit with a call to
snapshot_delete to create the new method snapshot_abort.
This way, we can cleanup the config and (try to) delete
the failed snapshot in one go, wrapped by lock_container.
---
 src/PVE/LXC.pm | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/PVE/LXC.pm b/src/PVE/LXC.pm
index f761f33..185c77e 100644
--- a/src/PVE/LXC.pm
+++ b/src/PVE/LXC.pm
@@ -1791,6 +1791,35 @@ my $snapshot_commit = sub {
     lock_container($vmid, 10 ,$updatefn);
 };
 
+my $snapshot_abort = sub {
+    my ($vmid, $snapname) = @_;
+
+    my $updatefn = sub {
+
+	my $conf = load_config($vmid);
+
+	die "missing snapshot lock\n"
+	    if !($conf->{lock} && $conf->{lock} eq 'snapshot');
+
+	die "snapshot '$snapname' does not exist\n"
+	    if !defined($conf->{snapshots}->{$snapname});
+
+	die "wrong snapshot state\n"
+	    if !($conf->{snapshots}->{$snapname}->{'snapstate'} &&
+		 $conf->{snapshots}->{$snapname}->{'snapstate'} eq "prepare");
+
+	delete $conf->{snapshots}->{$snapname}->{'snapstate'};
+	delete $conf->{lock};
+
+	write_config($vmid, $conf);
+
+	eval { snapshot_delete($vmid, $snapname, 1); };
+	warn "$@\n" if $@;
+    };
+
+    lock_container($vmid, 10 ,$updatefn);
+};
+
 sub has_feature {
     my ($feature, $conf, $storecfg, $snapname) = @_;
     
@@ -1827,8 +1856,8 @@ sub snapshot_create {
     
     eval {
 	if ($running) {
-	    PVE::Tools::run_command(['/usr/bin/lxc-freeze', '-n', $vmid]);
 	    $unfreeze = 1;
+	    PVE::Tools::run_command(['/usr/bin/lxc-freeze', '-n', $vmid]);
 	    PVE::Tools::run_command(['/bin/sync']);
 	};
 
@@ -1847,7 +1876,8 @@ sub snapshot_create {
     }
     
     if ($err) {
-	snapshot_delete($vmid, $snapname, 1);
+	eval { &$snapshot_abort($vmid, $snapname); };
+	warn "$@\n" if $@;
 	die "$err\n";
     }
 }
-- 
2.1.4