[pve-devel] [RFC v2 qemu/storage 00/10] storage plugin method to get qemu blockdevice options for volume

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

Changes in v2:
* Patch QEMU to support both keyring and rbd_cache_policy settings,
  it is much cleaner than generate per-volume (or technically would
  even be per-instance, as a volume could be re-used) temporary
  ceph.conf files. For keyring, we could also make sure to write the
  path to every storage's ceph.conf in pve8to9 and require it going
  forward, but supporting the option in QEMU seems to be the simplest.
  The rbd_cache_policy is truly a per-volume setting in Proxmox VE,
  which is specifically changed for EFI disks, so ceph.conf is just
  not the right place for that setting.
* Add a special 'hints' option to indicate when it's an EFI disk, so
  the RBD plugin can set the policy.
* Drop $snapshot parameter, currently there is no need to attach
  snapshots via -blockdev. They would need to be attached read-only
  too to not fail and this can always be added later.

When using -drive, storage plugins currently give us a path that QEMU
understands, some using special protocols such as 'iscsi://'. We'd
like to switch to using the more modern -blockdev for PVE 9. The
plan is to have the storage plugins return the very basic information
required to access the image, and qemu-server can then add other
settings like cache, aio, etc. on top. In fact, pretty similar to what
we have now for -drive, just with a structured hash rather than a
string.

This is also a prerequisite for qemu-storage-deamon, that would be
useful for TPM-as-qcow2 exported via NBD or FUSE or external backup
provider restore providing an NBD export for the provider to write to.

QEMU patches submitted upstream here:
https://lore.kernel.org/qemu-devel/20250515112908.383693-1-f.ebner@proxmox.com/

qemu:

Fiona Ebner (2):
  block/rbd: support selected key-value-pairs via QAPI
  block/rbd: support keyring option via QAPI

 block/rbd.c          | 81 ++++++++++++++++++++++++++++++++++++++++++++
 qapi/block-core.json | 40 ++++++++++++++++++++++
 2 files changed, 121 insertions(+)

storage:

Fiona Ebner (8):
  plugin: add method to get qemu blockdevice options for volume
  iscsi direct plugin: implement method to get qemu blockdevice options
  zfs iscsi plugin: implement new method to get qemu blockdevice options
  zfs pool plugin: implement method to get qemu blockdevice options
  rbd plugin: implement new method to get qemu blockdevice options
  plugin: qemu block device: add hints option and EFI disk hint
  plugin: qemu block device: add support for snapshot option
  plugin api: bump api version and age

 ApiChangeLog                         | 13 ++++
 src/PVE/Storage.pm                   | 21 ++++++-
 src/PVE/Storage/ISCSIDirectPlugin.pm | 17 +++++
 src/PVE/Storage/Plugin.pm            | 93 ++++++++++++++++++++++++++++
 src/PVE/Storage/RBDPlugin.pm         | 49 +++++++++++++++
 src/PVE/Storage/ZFSPlugin.pm         | 19 ++++++
 src/PVE/Storage/ZFSPoolPlugin.pm     | 12 ++++
 7 files changed, 222 insertions(+), 2 deletions(-)

-- 
2.39.5



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