Re: [pve-devel] [PATCH qemu-server 01/13] blockdev: cmdline: add blockdev syntax support

[Fiona Ebner <f.ebner@proxmox.com>]

Am 11.06.25 um 08:37 schrieb DERUMIER, Alexandre:
>>> Also, while the use case here shouldn't be cryptographically
>>> sensitive,
>>> you never know, so I'll just use a different hash function than sha1.
>>> I'll cut off the result from that hash to 30 hex digits. Then we
>>> still
>>> have one letter for the prefix of the node name.
> 
> so, maybe something like : 
> 
> $digest = substr(sha256_hex("${volname}+${snap}"),0,30);
> 
> ?
> 
> 
> I still unsure how to handle same volume multiple time (if we really
> want it). I was thinking to use the deviceid in the name (virtio0,..),
> but it don't work when you unplug/replug to a deviceid.

Why wouldn't it work?

> Maybe some kind of slot number like fabian have suggested, but I think
> it'll need  some kind of lookup.
> 
> or maybe, if we want same volume multiple volume, we just keep
> autogenerated qemu blockdev for this specific case, as anyway, we can't
> do snapshot, unplug, or other dynamic features.

My proposal is:

my sub get_node_name {
    my ($type, $drive_id, $volid, $snap) = @_;

    my $info = "drive=$drive_id,";
    $info .= "snap=$snap," if defined($snap);
    $info .= "volid=$volid";

    my $encoded = substr(Digest::SHA::sha256_hex($info), 0, 30);

    my $prefix = "";
    if ($type eq 'fmt') {
       $prefix = 'f';
    } elsif ($type eq 'file') {
       $prefix = 'e';
    } else {
       die "unknown node type '$type'";
    }
    # node-name must start with an alphabetical character
    return "${prefix}${encoded}";
}


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