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

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

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>
---
 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;
 }
-- 
2.30.2