[pve-devel] [PATCH storage] ZFS: mount subvols in activate_volume

[Fabian Ebner]

This makes containers work even if the subvolumes are not already
mounted beforehand for some reason. Without this patch, container
could quietly fail for e.g. start and full clone, because
bind-mounting still "worked" on the empty directory.

Signed-off-by: Fabian Ebner <f.ebner at proxmox.com>
---

This can be seen as an alternative to [0], which hasn't been applied
AFAICT. And this approach even works when the subvolume is not mounted
for a different reason than the one described in [0]. For example, I
ran into the problem by having a non-empty '/myzpool', causing 'myzpool'
to be not mountable, but 'myzpool/subvol-123-disk-0' would still be mountable.

[0]: https://pve.proxmox.com/pipermail/pve-devel/2020-March/042089.html

 PVE/Storage/ZFSPoolPlugin.pm | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/PVE/Storage/ZFSPoolPlugin.pm b/PVE/Storage/ZFSPoolPlugin.pm
index 10354b3..4a85732 100644
--- a/PVE/Storage/ZFSPoolPlugin.pm
+++ b/PVE/Storage/ZFSPoolPlugin.pm
@@ -546,9 +546,14 @@ sub activate_volume {
 
     my (undef, undef, undef, undef, undef, undef, $format) = $class->parse_volname($volname);
 
-    return 1 if $format ne 'raw';
-
-    $class->zfs_wait_for_zvol_link($scfg, $volname);
+    if ($format eq 'raw') {
+	$class->zfs_wait_for_zvol_link($scfg, $volname);
+    } elsif ($format eq 'subvol') {
+	my $mounted = $class->zfs_get_properties($scfg, 'mounted', "$scfg->{pool}/$volname");
+	if ($mounted !~ m/^yes$/) {
+	    $class->zfs_request($scfg, undef, 'mount', "$scfg->{pool}/$volname");
+	}
+    }
 
     return 1;
 }
-- 
2.20.1