Re: [pve-devel] [PATCH v3 storage 2/3] zfspool: add blockers parameter to volume_snapshot_is_possible

[Fabian Ebner <f.ebner@proxmox.com>]

Am 12.08.21 um 13:01 schrieb Fabian Ebner:
> useful for rollback, so that only the required replication snapshots
> can be removed, and it's possible to abort early without deleting any
> replication snapshots if there are other non-replication snasphots
> blocking rollback.
> 
> Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
> ---

Forgot to mention that this requires an APIVER+APIAGE bump.

>   PVE/Storage.pm               |  4 ++--
>   PVE/Storage/BTRFSPlugin.pm   |  2 +-
>   PVE/Storage/Plugin.pm        |  5 ++++-
>   PVE/Storage/ZFSPoolPlugin.pm | 23 +++++++++++++++++------
>   4 files changed, 24 insertions(+), 10 deletions(-)
> 
> diff --git a/PVE/Storage.pm b/PVE/Storage.pm
> index c04b5a2..3b3ce93 100755
> --- a/PVE/Storage.pm
> +++ b/PVE/Storage.pm
> @@ -269,13 +269,13 @@ sub volume_resize {
>   }
>   
>   sub volume_rollback_is_possible {
> -    my ($cfg, $volid, $snap) = @_;
> +    my ($cfg, $volid, $snap, $blockers) = @_;
>   
>       my ($storeid, $volname) = parse_volume_id($volid, 1);
>       if ($storeid) {
>           my $scfg = storage_config($cfg, $storeid);
>           my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
> -        return $plugin->volume_rollback_is_possible($scfg, $storeid, $volname, $snap);
> +        return $plugin->volume_rollback_is_possible($scfg, $storeid, $volname, $snap, $blockers);
>       } elsif ($volid =~ m|^(/.+)$| && -e $volid) {
>           die "snapshot rollback file/device '$volid' is not possible\n";
>       } else {
> diff --git a/PVE/Storage/BTRFSPlugin.pm b/PVE/Storage/BTRFSPlugin.pm
> index 411cab9..60fb027 100644
> --- a/PVE/Storage/BTRFSPlugin.pm
> +++ b/PVE/Storage/BTRFSPlugin.pm
> @@ -513,7 +513,7 @@ sub volume_snapshot {
>   }
>   
>   sub volume_rollback_is_possible {
> -    my ($class, $scfg, $storeid, $volname, $snap) = @_;
> +    my ($class, $scfg, $storeid, $volname, $snap, $blockers) = @_;
>   
>       return 1;
>   }
> diff --git a/PVE/Storage/Plugin.pm b/PVE/Storage/Plugin.pm
> index b1865cb..c265e53 100644
> --- a/PVE/Storage/Plugin.pm
> +++ b/PVE/Storage/Plugin.pm
> @@ -900,8 +900,11 @@ sub volume_snapshot {
>       return undef;
>   }
>   
> +# Asserts that a rollback to $snap on $volname is possible.
> +# If certain snapshots are preventing the rollback and $blockers is an array
> +# reference, the snapshot names can be pushed onto $blockers prior to dying.
>   sub volume_rollback_is_possible {
> -    my ($class, $scfg, $storeid, $volname, $snap) = @_;
> +    my ($class, $scfg, $storeid, $volname, $snap, $blockers) = @_;
>   
>       return 1;
>   }
> diff --git a/PVE/Storage/ZFSPoolPlugin.pm b/PVE/Storage/ZFSPoolPlugin.pm
> index c2a0385..8d79f38 100644
> --- a/PVE/Storage/ZFSPoolPlugin.pm
> +++ b/PVE/Storage/ZFSPoolPlugin.pm
> @@ -480,18 +480,29 @@ sub volume_snapshot_rollback {
>   }
>   
>   sub volume_rollback_is_possible {
> -    my ($class, $scfg, $storeid, $volname, $snap) = @_;
> +    my ($class, $scfg, $storeid, $volname, $snap, $blockers) = @_;
>   
>       # can't use '-S creation', because zfs list won't reverse the order when the
>       # creation time is the same second, breaking at least our tests.
>       my $snapshots = $class->zfs_get_sorted_snapshot_list($scfg, $volname, ['-s', 'creation']);
> -    my $recentsnap = $snapshots->[-1];
>   
> -    die "can't rollback, no snapshots exist at all\n"
> -	if !defined($recentsnap);
> +    my $found;
> +    $blockers //= []; # not guaranteed to be set by caller
> +    for my $snapshot ($snapshots->@*) {
> +	if ($snapshot eq $snap) {
> +	    $found = 1;
> +	} elsif ($found) {
> +	    push $blockers->@*, $snapshot;
> +	}
> +    }
> +
> +    my $volid = "${storeid}:${volname}";
> +
> +    die "can't rollback, snapshot '$snap' does not exist on '$volid'\n"
> +	if !$found;
>   
> -    die "can't rollback, '$snap' is not most recent snapshot\n"
> -	if $snap ne $recentsnap;
> +    die "can't rollback, '$snap' is not most recent snapshot on '$volid'\n"
> +	if scalar($blockers->@*) > 0;
>   
>       return 1;
>   }
>