Re: [pve-devel] [PATCH qemu-server 2/6] drive: factor out read-only helper

[Stefan Reiter <s.reiter@proxmox.com>]

On 6/4/21 11:47 AM, Fabian Grünbichler wrote:
> we also need it for efidisks.
> 
> Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
> ---
>   PVE/QemuServer.pm       |  8 ++------
>   PVE/QemuServer/Drive.pm | 10 ++++++++++
>   2 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index 25ac052..0d49415 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -48,7 +48,7 @@ use PVE::QemuServer::Helpers qw(min_version config_aware_timeout);
>   use PVE::QemuServer::Cloudinit;
>   use PVE::QemuServer::CGroup;
>   use PVE::QemuServer::CPUConfig qw(print_cpu_device get_cpu_options);
> -use PVE::QemuServer::Drive qw(is_valid_drivename drive_is_cloudinit drive_is_cdrom parse_drive print_drive);
> +use PVE::QemuServer::Drive qw(is_valid_drivename drive_is_cloudinit drive_is_cdrom drive_is_read_only parse_drive print_drive);
>   use PVE::QemuServer::Machine;
>   use PVE::QemuServer::Memory;
>   use PVE::QemuServer::Monitor qw(mon_cmd);
> @@ -3662,11 +3662,7 @@ sub config_to_command {
>   	my $drive_cmd = print_drive_commandline_full($storecfg, $vmid, $drive, $pbs_name);
>   
>   	# extra protection for templates, but SATA and IDE don't support it..
> -	my $read_only = PVE::QemuConfig->is_template($conf)
> -	    && $drive->{interface} ne 'sata'
> -	    && $drive->{interface} ne 'ide';
> -
> -	$drive_cmd .= ',readonly=on' if $read_only;
> +	$drive_cmd .= ',readonly=on' if drive_is_read_only($conf, $drive);
>   
>   	push @$devices, '-drive',$drive_cmd;
>   	push @$devices, '-device', print_drivedevice_full(
> diff --git a/PVE/QemuServer/Drive.pm b/PVE/QemuServer/Drive.pm
> index 146a4ab..0408e32 100644
> --- a/PVE/QemuServer/Drive.pm
> +++ b/PVE/QemuServer/Drive.pm
> @@ -12,6 +12,7 @@ our @EXPORT_OK = qw(
>   is_valid_drivename
>   drive_is_cloudinit
>   drive_is_cdrom
> +drive_is_read_only
>   parse_drive
>   print_drive
>   );
> @@ -422,6 +423,15 @@ sub drive_is_cdrom {
>       return $drive && $drive->{media} && ($drive->{media} eq 'cdrom');
>   }
>   
> +sub drive_is_read_only {

I really don't like this name, this checks if the drive *should* be 
read-only, and only related to template backups, not in general.

Maybe 'drive_template_read_only'?

The function does two pretty unrelated things in general IMO, so maybe 
it would be clearer to do the is_template check at call site and make 
this 'drive_supports_read_only', even if it causes a little bit more 
duplication.

> +    my ($conf, $drive) = @_;
> +
> +    return 0 if !PVE::QemuConfig->is_template($conf);
> +
> +    # don't support being marked read-only
> +    return $drive->{interface} ne 'sata' && $drive->{interface} ne 'ide';
> +}
> +
>   # ideX = [volume=]volume-id[,media=d][,cyls=c,heads=h,secs=s[,trans=t]]
>   #        [,snapshot=on|off][,cache=on|off][,format=f][,backup=yes|no]
>   #        [,rerror=ignore|report|stop][,werror=enospc|ignore|report|stop]
>