From mboxrd@z Thu Jan 1 00:00:00 1970
Return-Path: <pve-devel-bounces@lists.proxmox.com>
Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68])
by lore.proxmox.com (Postfix) with ESMTPS id 444861FF164
for <inbox@lore.proxmox.com>; Fri, 9 May 2025 16:15:23 +0200 (CEST)
Received: from firstgate.proxmox.com (localhost [127.0.0.1])
by firstgate.proxmox.com (Proxmox) with ESMTP id 42DFE3F1BC;
Fri, 9 May 2025 16:15:40 +0200 (CEST)
From: Fiona Ebner <f.ebner@proxmox.com>
To: pve-devel@lists.proxmox.com
Date: Fri, 9 May 2025 16:15:30 +0200
Message-Id: <20250509141532.111458-3-f.ebner@proxmox.com>
X-Mailer: git-send-email 2.39.5
In-Reply-To: <20250509141532.111458-1-f.ebner@proxmox.com>
References: <20250509141532.111458-1-f.ebner@proxmox.com>
MIME-Version: 1.0
X-SPAM-LEVEL: Spam detection results: 0
AWL -0.035 Adjusted score from AWL reputation of From: address
BAYES_00 -1.9 Bayes spam probability is 0 to 1%
DMARC_MISSING 0.1 Missing DMARC policy
KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment
SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record
SPF_PASS -0.001 SPF: sender matches SPF record
Subject: [pve-devel] [RFC storage 1/3] plugin: add method to get qemu
blockdevice options for volume
X-BeenThere: pve-devel@lists.proxmox.com
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Proxmox VE development discussion <pve-devel.lists.proxmox.com>
List-Unsubscribe: <https://lists.proxmox.com/cgi-bin/mailman/options/pve-devel>,
<mailto:pve-devel-request@lists.proxmox.com?subject=unsubscribe>
List-Archive: <http://lists.proxmox.com/pipermail/pve-devel/>
List-Post: <mailto:pve-devel@lists.proxmox.com>
List-Help: <mailto:pve-devel-request@lists.proxmox.com?subject=help>
List-Subscribe: <https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel>,
<mailto:pve-devel-request@lists.proxmox.com?subject=subscribe>
Reply-To: Proxmox VE development discussion <pve-devel@lists.proxmox.com>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Errors-To: pve-devel-bounces@lists.proxmox.com
Sender: "pve-devel" <pve-devel-bounces@lists.proxmox.com>
There intentionally is only handling for absolute paths in the default
plugin implementation. Any plugin requiring more needs to implement
the method itself.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
I discussed this with Fabian off-list. With PVE 9 being a major
release and most popular plugins not using special protocols like
'rbd://', this seems acceptable. He'll also give a heads-up to known
plugin developers with other changes for PVE 9 in time.
For NBD, etc. qemu-server should construct the blockdev object.
Still missing API bump + Changelog
Did not test snapshots yet.
src/PVE/Storage.pm | 19 ++++++++++++
src/PVE/Storage/Plugin.pm | 64 +++++++++++++++++++++++++++++++++++++++
2 files changed, 83 insertions(+)
diff --git a/src/PVE/Storage.pm b/src/PVE/Storage.pm
index d0a696a..5915395 100755
--- a/src/PVE/Storage.pm
+++ b/src/PVE/Storage.pm
@@ -710,6 +710,25 @@ sub abs_filesystem_path {
return $path;
}
+sub qemu_blockdev_options {
+ my ($cfg, $volid, $snapname) = @_;
+
+ my ($storeid, $volname) = parse_volume_id($volid);
+
+ my $scfg = storage_config($cfg, $storeid);
+
+ my $plugin = PVE::Storage::Plugin->lookup($scfg->{type});
+
+ my ($vtype) = $plugin->parse_volname($volname);
+ die "cannot use volume of type '$vtype' as a QEMU blockdevice\n"
+ if $vtype ne 'images' && $vtype ne 'iso' && $vtype ne 'import';
+
+ die "QEMU blockdevice - 'snapname' argument is not supported for vtype '$vtype'"
+ if $snapname && $vtype ne 'images';
+
+ return $plugin->qemu_blockdev_options($scfg, $storeid, $volname, $snapname);
+}
+
# used as last resort to adapt volnames when migrating
my $volname_for_storage = sub {
my ($cfg, $storeid, $name, $vmid, $format) = @_;
diff --git a/src/PVE/Storage/Plugin.pm b/src/PVE/Storage/Plugin.pm
index 4e16420..dc3c6df 100644
--- a/src/PVE/Storage/Plugin.pm
+++ b/src/PVE/Storage/Plugin.pm
@@ -1880,6 +1880,70 @@ sub rename_volume {
return "${storeid}:${base}${target_vmid}/${target_volname}";
}
+=pod
+
+=head3 qemu_blockdev_options
+
+ $blockdev = $plugin->qemu_blockdev_options($scfg, $storeid, $volname, $snapname)
+
+Returns a hash reference with the basic options needed to open the volume via QEMU's C<-blockdev>
+API. This at least requires a C<< $blockdev->{driver} >> and a reference to the image, e.g.
+C<< $blockdev->{filename} >> for the C<file> driver. For files, the C<file> driver can be used. For
+host block devices, the C<host_device> driver can be used. The plugin must not set options like
+C<cache> or C<aio>. Those are managed by qemu-server and will be overwritten. For other available
+drivers and the exact specification of the options, see
+L<https://qemu.readthedocs.io/en/master/interop/qemu-qmp-ref.html#object-QMP-block-core.BlockdevOptions>
+
+While Perl does not have explicit types, the result will need to be converted to JSON later and
+match the QMP specification (see link above), so implicit types are important. In the return value,
+use C<JSON::true> and C<JSON::false> for booleans, C<"$value"> for strings, and C<int($value)> for
+integers.
+
+Arguments:
+
+=over
+
+=item C<$scfg>
+
+The hash reference with the storage configuration.
+
+=item C<$storeid>
+
+The storage ID.
+
+=item C<$volume>
+
+The volume name.
+
+=item C<$snapname>
+
+(optional) The snapshot name. Set when the associated snapshot should be opened
+rather than the volume itself.
+
+=back
+
+=cut
+sub qemu_blockdev_options {
+ my ($class, $scfg, $storeid, $volname, $snapname) = @_;
+
+ my $blockdev = {};
+
+ my ($path) = $class->path($scfg, $volname, $storeid, $snapname);
+
+ if ($path =~ m|^/|) {
+ # The 'file' driver only works for regular files. The check below is taken from
+ # block/file-posix.c:hdev_probe_device() in QEMU. Do not bother with detecting 'host_cdrom'
+ # devices here, those are not managed by the storage layer.
+ my $st = File::stat::stat($path);
+ my $driver = (S_ISCHR($st->mode) || S_ISBLK($st->mode)) ? 'host_device' : 'file';
+ $blockdev = { driver => $driver, filename => $path };
+ } else {
+ die "storage plugin doesn't implement qemu_blockdev_options() method\n";
+ }
+
+ return $blockdev;
+}
+
# Used by storage plugins for external backup providers. See PVE::BackupProvider::Plugin for the API
# the provider needs to implement.
#
--
2.39.5
_______________________________________________
pve-devel mailing list
pve-devel@lists.proxmox.com
https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel