[pve-devel] [PATCH guest-common 1/3] snapshot_rollback: flock earlier

[Fabian Ebner]

One not-patch-related observation inline.

On 27.04.20 10:24, Fabian Grünbichler wrote:
> to protect checks against concurrent modifications
> 
> Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
> ---
> 
> Notes:
>      bested viewed with --patience -w
> 
>   PVE/AbstractConfig.pm | 45 +++++++++++++++++++++----------------------
>   1 file changed, 22 insertions(+), 23 deletions(-)
> 
> diff --git a/PVE/AbstractConfig.pm b/PVE/AbstractConfig.pm
> index 15368de..70311df 100644
> --- a/PVE/AbstractConfig.pm
> +++ b/PVE/AbstractConfig.pm
> @@ -919,9 +919,10 @@ sub snapshot_rollback {
>   
>       my $storecfg = PVE::Storage::config();
>   
> -    my $conf = $class->load_config($vmid);
> +    my $data = {};
>   
>       my $get_snapshot_config = sub {
> +	my ($conf) = @_;
>   
>   	die "you can't rollback if vm is a template\n" if $class->is_template($conf);
>   
> @@ -932,32 +933,30 @@ sub snapshot_rollback {
>   	return $res;
>       };
>   
> -    my $repl_conf = PVE::ReplicationConfig->new();
> -    if ($repl_conf->check_for_existing_jobs($vmid, 1)) {
> -	# remove all replication snapshots
> -	my $volumes = $class->get_replicatable_volumes($storecfg, $vmid, $conf, 1);
> -	my $sorted_volids = [ sort keys %$volumes ];
> -
> -	# remove all local replication snapshots (jobid => undef)
> -	my $logfunc = sub { my $line = shift; chomp $line; print "$line\n"; };
> -	PVE::Replication::prepare($storecfg, $sorted_volids, undef, 0, undef, $logfunc);
> -    }
> -
> -    my $snap = &$get_snapshot_config();
> -
> -    $class->foreach_volume($snap, sub {
> -	my ($vs, $volume) = @_;
> -
> -	$class->__snapshot_rollback_vol_possible($volume, $snapname);
> -    });
> -
> -    my $data = {};
> +    my $snap;
>   
>       my $updatefn = sub {
> +	my $conf = $class->load_config($vmid);
> +	$snap = $get_snapshot_config->($conf);
>   
> -	$conf = $class->load_config($vmid);
> +	if ($prepare) {
> +	    my $repl_conf = PVE::ReplicationConfig->new();
> +	    if ($repl_conf->check_for_existing_jobs($vmid, 1)) {
> +		# remove all replication snapshots
> +		my $volumes = $class->get_replicatable_volumes($storecfg, $vmid, $conf, 1);
> +		my $sorted_volids = [ sort keys %$volumes ];
> +
> +		# remove all local replication snapshots (jobid => undef)
> +		my $logfunc = sub { my $line = shift; chomp $line; print "$line\n"; };
> +		PVE::Replication::prepare($storecfg, $sorted_volids, undef, 0, undef, $logfunc);

This has nothing to do with the locking/this patch, but here we'd need 
to call prepare with last_sync=1 instead of last_sync=0, no? This is 
because of commit a1dfeff3a8502544123245ea61ad62cbe97803b7 which made 
last_sync=0 a special case and changed the behavior. I can send a patch 
once this is applied.

> +	    }
> +
> +	    $class->foreach_volume($snap, sub {
> +	       my ($vs, $volume) = @_;
>   
> -	$snap = &$get_snapshot_config();
> +	       $class->__snapshot_rollback_vol_possible($volume, $snapname);
> +	    });
> +        }
>   
>   	die "unable to rollback to incomplete snapshot (snapstate = $snap->{snapstate})\n"
>   	    if $snap->{snapstate};
>