[pve-devel] [PATCH qemu-server v2] drives: expose 'readonly' flag of qemu for scsi/virtio

Dominik Csapak d.csapak at proxmox.com
Tue Sep 28 11:02:11 CEST 2021


this allows a user to set a drive to 'read-only'. This can be useful
if a disk should not be written to, or if the backing file/source is
not writable (like a mapped pbs backup to /dev/loopX).

while this could also be achieved by setting 'snapshot=1', this would
create a temporary file in /var/tmp which can get quite big.

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
changes from v1:
* limit that setting to scsi/virtio as it is not possible to use it on
  ide/sata

 PVE/QemuServer.pm       | 10 ++++++----
 PVE/QemuServer/Drive.pm | 11 +++++++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 0fb8628..5209f51 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -1569,10 +1569,12 @@ sub print_drive_commandline_full {
 	$opts .= ",$o=$drive->{$o}" if defined($drive->{$o});
     }
 
-    # snapshot only accepts on|off
-    if (defined($drive->{snapshot})) {
-	my $v = $drive->{snapshot} ? 'on' : 'off';
-	$opts .= ",snapshot=$v";
+    # some options only accepts on|off
+    foreach my $o (qw(snapshot readonly)) {
+	if (defined($drive->{$o})) {
+	    my $v = $drive->{$o} ? 'on' : 'off';
+	    $opts .= ",$o=$v";
+	}
     }
 
     foreach my $type (['', '-total'], [_rd => '-read'], [_wr => '-write']) {
diff --git a/PVE/QemuServer/Drive.pm b/PVE/QemuServer/Drive.pm
index 5110190..af7aafe 100644
--- a/PVE/QemuServer/Drive.pm
+++ b/PVE/QemuServer/Drive.pm
@@ -175,6 +175,14 @@ my %queues_fmt = (
     }
 );
 
+my %readonly_fmt = (
+    readonly => {
+	type => 'boolean',
+	description => "Whether the drive is read-only.",
+	optional => 1,
+    },
+);
+
 my %scsiblock_fmt = (
     scsiblock => {
 	type => 'boolean',
@@ -269,6 +277,7 @@ my $scsi_fmt = {
     %drivedesc_base,
     %iothread_fmt,
     %queues_fmt,
+    %readonly_fmt,
     %scsiblock_fmt,
     %ssd_fmt,
     %wwn_fmt,
@@ -297,6 +306,7 @@ PVE::JSONSchema::register_standard_option("pve-qm-sata", $satadesc);
 my $virtio_fmt = {
     %drivedesc_base,
     %iothread_fmt,
+    %readonly_fmt,
 };
 my $virtiodesc = {
     optional => 1,
@@ -311,6 +321,7 @@ my $alldrive_fmt = {
     %iothread_fmt,
     %model_fmt,
     %queues_fmt,
+    %readonly_fmt,
     %scsiblock_fmt,
     %ssd_fmt,
     %wwn_fmt,
-- 
2.30.2





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