[pve-devel] [PATCH v7 series 0/5] disk reassign: add new feature

[Aaron Lauterer]

This series implements a new feature which allows users to easily
reassign disks between VMs. Currently this is only possible with one of
the following manual steps:

* rename the disk image/file and do a `qm rescan`
* configure the disk manually and use the old image name, having an
    image for VM A assigned to VM B

The latter can cause unexpected behavior because PVE expects that the
VMID in a disk name always corresponds to the VM it is assigned to. Thus
when a disk, original from VM A was manually configured as disk for VM B
it happens that, when deleting VM A, the disk in question will be
deleted as well because it still had the VMID of VM A in it's name.

To issue a reassign from the CLI run:

qm reassign-disk <source VMID> <target VMID> <source disk> <target disk>

where <source/target disk> is the config key of the disk, e.g. ide0,
scsi1 and so on.

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

v6 -> v7:
This was a rather large change to the previous version. I hope I
    incorporated all suggestions and hints and did not miss anything.
    More details are usually found in the direct patches.

* removed original patch 4 as it is not needed (thx @febner for the hint)
* added another (optional) patch to align move_disk to use a dash
  instead of an underscore
* make sure storage is activated
* restructure storage plugins so that dir based ones are handled
  directly in plugin.pm with API version checks for external plugins
* add target disk key
* use update_vm_api to add the disk to the new VM (hotplug if possible)
* removed cluster log
* reordered reassing procedure
* changed worker ID to show source and target better

v5 -> v6:
* guard Replication snapshot cleanup
* add permission check for target vmid
* changed regex to match unused keys better
* refactor dir based feature check to reduce code repetition

v4 -> v5:
* rebase on current master
* reorder patches
* rename `drive_key` to `drive_name`
    thanks @Dominic for pointing out that there already are a lot of
    different names in use for this [0] and not to invent another one 
* implemented suggested changes from Fabian [1][2]. More directly in the
    patches themselves

v3 -> v4:
* revert intermediate storage plugin for directory based plugins
* add a `die "not supported"` method in Plugin.pm
* dir based plugins now call the file_reassign_volume method in
  Plugin.pm as the generic file/directory based method
* restored old `volume_has_feature` method in Plugin.pm and override it
  in directory based plugins to check against the new `reassign` feature
  (not too happy about the repetition for each plugin)
* task description mapping has been moved from widget-toolkit to
  pve-manager/utils


v2 -> v3:
* change locking approach
* add more checks
* add intermedia storage plugin for directory based plugins
* use feature flags
* split up the reassign method to have a dedicated method for the
    renaming itself
* handle linked clones
* clean up if disk used to be replicated

I hope I didn't forget anything major.

v1 -> v2:
print info about the new disk volid and key at the end of the job so it
shows up in the CLI output and task log

Changes from RFC -> V1:
* support to reassign unused disks
* digest for target vm config
* reorder the checks a bit
* adding another one to check if the given key for the disk even exists
  in the config.

[0] https://lists.proxmox.com/pipermail/pve-devel/2020-November/045986.html
[1] https://lists.proxmox.com/pipermail/pve-devel/2020-November/046031.html
[2] https://lists.proxmox.com/pipermail/pve-devel/2020-November/046030.html

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

 PVE/Storage.pm               | 19 +++++++++++--
 PVE/Storage/LVMPlugin.pm     | 34 +++++++++++++++++++++++
 PVE/Storage/LvmThinPlugin.pm |  1 +
 PVE/Storage/Plugin.pm        | 52 ++++++++++++++++++++++++++++++++++++
 PVE/Storage/RBDPlugin.pm     | 37 +++++++++++++++++++++++++
 PVE/Storage/ZFSPoolPlugin.pm | 38 ++++++++++++++++++++++++++
 6 files changed, 179 insertions(+), 2 deletions(-)

qemu-server: Aaron Lauterer (3):
  disk reassign: add API endpoint
  cli: disk reassign: add reassign_disk to qm command
  cli: qm: change move_disk parameter to move-disk

 PVE/API2/Qemu.pm        | 220 ++++++++++++++++++++++++++++++++++++++++
 PVE/CLI/qm.pm           |   5 +-
 PVE/QemuServer/Drive.pm |   4 +
 3 files changed, 228 insertions(+), 1 deletion(-)

manager: Aaron Lauterer (1):
  ui: tasks: add qmreassign task description

 www/manager6/Utils.js | 1 +
 1 file changed, 1 insertion(+)

-- 
2.20.1