[pve-devel] [PATCH v5 storage qemu-server container 0/9] move disk or volume to other guests

Aaron Lauterer a.lauterer at proxmox.com
Tue Nov 9 15:55:31 CET 2021

This version 5 came to be after Fabian did notice that exposing the
'find_free_volname' could cause some troubles down the line since it
could be seen as an incompatible change in the storage API, especially
of other parts will start using it as well.

We discussed it off list and the current version is the result of that.
We drop all of find_free_volname for now and change the parameters given
to the rename functions which now take the source volid, target vmid and
target volname. The latter two are either or optional. If the target
vmid is not given, it will be set to the source vmid. If no target
volname is given, the rename function will request the next free one
itself within the storage plugin (find_free_diskname).

This makes it possible to keep our storage api compatible and we can
continue working on making it possible to give disk images a more custom
name. The raname functions as implemented should be able to deal with
this situation already (only did light testing on this).

If, in the future it is necessary to have something like
find_free_volname as part of the storage api, we can add it again at the
right time, where a storage api version bump is okay.

We will have to discuss if we want to use v5 or are okay with v4.

Additionally I split up adding valid unused volume keys in the
LXC/Config.pm into its own patch as it is on the Qemu side.

Previous cover letter follows:

This is the continuation of 'disk-reassign' but instead of a separate
API endpoint we now follow the approach to make it part of the
'move-disk' and 'move-volume' endpoints for VMs and containers.

The main idea is to make it easy to move a disk/volume to another guest.
Currently this is a manual and error prone process that requires
knowledge of how PVE handles disks/volumes and the mapping which guest
they belong to.

With this, the 'qm move-disk' and 'pct move-volume' are changed in the
way that the storage parameter is optional as well as the new
target-vmid and target-{disk,volume}. This will keep old calls to move the
disk/volume to another storage working. To move to another guest, the
storage needs to be omitted.

The following storage types are implemented at the moment:
* dir based ones
* (thin) LVM
* Ceph RBD

Most parts of the disk-reassign code has been taken and moved into the
'move_disk' and 'move_volume' endpoints with conditional checking if the
reassign code or the move to other storage code is meant to run
depending on the given parameters.

Changes since v4:
* remove find_free_volname completely
* change rename functions to take either target_vmid or target_volname
  as parameter. The target_volname as parameter makes it possible to
  easily implement custom renaming in the future. If no target_volname
  is given, it will use find_free_diskname to find the next free one.
* removed calls to find_free_volname in the container und qemu APIs

Changes since v3:
* added check if $vmid exists in $vmlist
* added check if volume if part of a snapshot (containers, qemu already
    had it)
* added section in storage/ApiChangeLog
* code style issues

Changes since v2:
* fixed base image handling
* fixed code style issues

Changes since v1 [2] (thx @ Fabian_E for the reviews!):
* drop exposed 'find_free_diskname' method
* drop 'wants_fmt_suffix' method (not needed anymore)
* introduce 'find_free_volname' which decides if only the diskname is
  needed or the longer path for directory based storages
* use $source_volname instead of $source_volid -> avoids some extra
  calls to get to $source_volname again
* make --target-{disk,volume} optional and fall back to source key
* smaller fixes in code quality and using existing functions like
  'parse_volname' instead of a custom regex (possible with the new

Changes since the RFC [1]:
* added check if target guest is replicated and fail if storage does not
  support replication
* only pass minimum of needed parameters to the storage layer and infer
  other needed information from that
* lock storage and check if the volume aready exists (handling a
  possible race condition between calling find_free_disk and the actual
* use a helper method to determine if the plugin needs the fmt suffix
  in the volume name
* getting format of the source and pass it to find_free_disk
* style fixes (long lines, multiline post-if, ...)

[1] https://lists.proxmox.com/pipermail/pve-devel/2021-June/048400.html
[2] https://lists.proxmox.com/pipermail/pve-devel/2021-July/049445.html

storage: Aaron Lauterer (1):
  add disk rename feature

 ApiChangeLog                 | 10 ++++++++++
 PVE/Storage.pm               | 25 ++++++++++++++++++++++--
 PVE/Storage/LVMPlugin.pm     | 34 ++++++++++++++++++++++++++++++++
 PVE/Storage/LvmThinPlugin.pm |  1 +
 PVE/Storage/Plugin.pm        | 38 ++++++++++++++++++++++++++++++++++++
 PVE/Storage/RBDPlugin.pm     | 34 ++++++++++++++++++++++++++++++++
 PVE/Storage/ZFSPoolPlugin.pm | 31 +++++++++++++++++++++++++++++
 7 files changed, 171 insertions(+), 2 deletions(-)

qemu-server: Aaron Lauterer (4):
  cli: qm: change move_disk to move-disk
  Drive: add valid_drive_names_with_unused
  api: move-disk: add move to other VM
  api: move-disk: cleanup very long lines

 PVE/API2/Qemu.pm        | 227 ++++++++++++++++++++++++++++++++++++++--
 PVE/CLI/qm.pm           |   3 +-
 PVE/QemuServer/Drive.pm |   4 +
 3 files changed, 223 insertions(+), 11 deletions(-)

container: Aaron Lauterer (4):
  cli: pct: change move_volume to move-volume
  Config: add valid_volume_keys_with_unused
  api: move-volume: add move to another container
  api: move-volume: cleanup very long lines

 src/PVE/API2/LXC.pm   | 302 ++++++++++++++++++++++++++++++++++++++----
 src/PVE/CLI/pct.pm    |   3 +-
 src/PVE/LXC/Config.pm |   9 ++
 3 files changed, 285 insertions(+), 29 deletions(-)


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