fix #5071: zfs over iscsi: add 'zfs-base-path' configuration option

Use '/dev/zvol' as a base path for new storages for providers 'iet'
and 'LIO', because that is what modern distributions use.

This is a breaking change regarding the addition of new storages on
older distributions, but it's enough to specify the base path '/dev'
explicitly for setups that require it.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Tested-by: Christoph Heiss <c.heiss@proxmox.com>
Link: https://lore.proxmox.com/20250605111109.52712-1-f.ebner@proxmox.com

src/PVE/Storage/LunCmd/Comstar.pm

@@ -32,7 +32,8 @@ my $get_lun_cmd_map = sub {
 };
 
 sub get_base {
-    return '/dev/zvol/rdsk';
+    my ($scfg) = @_;
+    return $scfg->{'zfs-base-path'} || '/dev/zvol/rdsk';
 }
 
 sub run_lun_command {

src/PVE/Storage/LunCmd/Iet.pm

@@ -138,7 +138,7 @@ my $parser = sub {
 
     my $line = 0;
 
-    my $base = get_base;
+    my $base = get_base($scfg);
     my $config = $get_config->($scfg);
     my @cfgfile = split "\n", $config;
 
@@ -482,7 +482,8 @@ sub run_lun_command {
 }
 
 sub get_base {
-    return '/dev';
+    my ($scfg) = @_;
+    return $scfg->{'zfs-base-path'} || '/dev';
 }
 
 1;

src/PVE/Storage/LunCmd/Istgt.pm

@@ -306,7 +306,7 @@ my $parser = sub {
     $CONFIG =~ s/\n$//;
     die "$scfg->{target}: Target not found" unless $SETTINGS->{targets};
     my $max = $SETTINGS->{targets};
-    my $base = get_base;
+    my $base = get_base($scfg);
 
     for (my $i = 1; $i <= $max; $i++) {
         my $target = $SETTINGS->{nodebase} . ':' . $SETTINGS->{"LogicalUnit$i"}->{TargetName};
@@ -612,7 +612,8 @@ sub run_lun_command {
 }
 
 sub get_base {
-    return '/dev/zvol';
+    my ($scfg) = @_;
+    return $scfg->{'zfs-base-path'} || '/dev/zvol';
 }
 
 1;

src/PVE/Storage/LunCmd/LIO.pm

@@ -231,7 +231,7 @@ my $extract_volname = sub {
     my ($scfg, $lunpath) = @_;
     my $volname = undef;
 
-    my $base = get_base;
+    my $base = get_base($scfg);
     if ($lunpath =~ /^$base\/$scfg->{pool}\/([\w\-]+)$/) {
         $volname = $1;
         my $prefix = $get_backstore_prefix->($scfg);
@@ -422,7 +422,8 @@ sub run_lun_command {
 }
 
 sub get_base {
-    return '/dev';
+    my ($scfg) = @_;
+    return $scfg->{'zfs-base-path'} || '/dev';
 }
 
 1;