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

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

[Dominik Csapak]

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@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

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

[Fabian Grünbichler]

On September 28, 2021 11:02 am, Dominik Csapak wrote:
> 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@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 => {

we have a very similar CT mountpoint property called 'ro', might make sense 
to have it consistent?

> +	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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