[PATCH-SERIES v8 pve-storage/qemu-server] add external qcow2 snapshot support

Alexandre Derumier alexandre.derumier at groupe-cyllene.com
Wed Jul 9 18:21:45 CEST 2025


This patch series implement qcow2 external snapshot support for files && lvm volumes

The current internal qcow2 snapshots have bad write performance because no metadatas can be preallocated.

This is particulary visible on a shared filesystem like ocfs2 or gfs2.

Also other bugs are freeze/lock reported by users since years on snapshots delete on nfs
(The disk access seem to be frozen during all the delete duration)

This also open doors for remote snapshot export-import for storage replication.

Changelog v8:
    storage :
     - fix Fabian comments
     - add rename_snapshot   
     - add qemu_resize
     - plugin: restrict volnames
     - plugin: use 'external-snapshots' instead 'snapext'
    qemu-server:
     - fix efi test with wrong volnames vm-disk-100-0.raw
     - use rename_snapshot
MAIN TODO:
    - add snapshots tests in both pve-storage && qemu-server
    - better handle snapshot failure with multiple disks


pve-storage:

Alexandre Derumier (13):
  plugin: add qemu_img_create
  plugin: add qemu_img_create_qcow2_backed
  plugin: add qemu_img_info
  plugin: add qemu_img_measure
  plugin: add qemu_img_resize
  rbd && zfs : create_base : remove $running param from volume_snapshot
  storage: volume_snapshot: add $running param
  storage: add rename_snapshot method
  storage: add volume_support_qemu_snapshot
  plugin: fix volname parsing
  qcow2: add external snapshot support
  lvmplugin: add qcow2 snapshot
  tests: add lvmplugin test

 ApiChangeLog                         |  15 +
 src/PVE/Storage.pm                   |  45 ++-
 src/PVE/Storage/BTRFSPlugin.pm       |   6 +
 src/PVE/Storage/CIFSPlugin.pm        |   1 +
 src/PVE/Storage/Common.pm            |  33 ++
 src/PVE/Storage/DirPlugin.pm         |  11 +
 src/PVE/Storage/ESXiPlugin.pm        |   8 +-
 src/PVE/Storage/ISCSIDirectPlugin.pm |   2 +-
 src/PVE/Storage/LVMPlugin.pm         | 571 +++++++++++++++++++++-----
 src/PVE/Storage/LvmThinPlugin.pm     |   8 +-
 src/PVE/Storage/NFSPlugin.pm         |   1 +
 src/PVE/Storage/PBSPlugin.pm         |   2 +-
 src/PVE/Storage/Plugin.pm            | 518 +++++++++++++++++++++---
 src/PVE/Storage/RBDPlugin.pm         |  18 +-
 src/PVE/Storage/ZFSPlugin.pm         |   4 +-
 src/PVE/Storage/ZFSPoolPlugin.pm     |   8 +-
 src/test/Makefile                    |   5 +-
 src/test/run_test_lvmplugin.pl       | 577 +++++++++++++++++++++++++++
 18 files changed, 1662 insertions(+), 171 deletions(-)
 create mode 100755 src/test/run_test_lvmplugin.pl

qemu-server :

Alexandre Derumier (4):
  qemu_img convert : add external snapshot support
  blockdev: add backing_chain support
  qcow2: add external snapshot support
  tests: fix efi vm-disk-100-0.raw -> vm-100-disk-0.raw

 src/PVE/QemuConfig.pm                         |   4 +-
 src/PVE/QemuServer.pm                         | 132 +++++--
 src/PVE/QemuServer/Blockdev.pm                | 345 +++++++++++++++++-
 src/PVE/QemuServer/QemuImage.pm               |   6 +-
 src/test/cfg2cmd/efi-raw-old.conf             |   2 +-
 src/test/cfg2cmd/efi-raw-old.conf.cmd         |   2 +-
 src/test/cfg2cmd/efi-raw-template.conf        |   2 +-
 src/test/cfg2cmd/efi-raw-template.conf.cmd    |   2 +-
 src/test/cfg2cmd/efi-raw.conf                 |   2 +-
 src/test/cfg2cmd/efi-raw.conf.cmd             |   2 +-
 src/test/cfg2cmd/efi-secboot-and-tpm-q35.conf |   2 +-
 .../cfg2cmd/efi-secboot-and-tpm-q35.conf.cmd  |   2 +-
 src/test/cfg2cmd/efi-secboot-and-tpm.conf     |   2 +-
 src/test/cfg2cmd/efi-secboot-and-tpm.conf.cmd |   2 +-
 src/test/cfg2cmd/sev-es.conf                  |   2 +-
 src/test/cfg2cmd/sev-es.conf.cmd              |   2 +-
 src/test/cfg2cmd/sev-std.conf                 |   2 +-
 src/test/cfg2cmd/sev-std.conf.cmd             |   2 +-
 src/test/cfg2cmd/simple-backingchain.conf     |  25 ++
 src/test/cfg2cmd/simple-backingchain.conf.cmd |  33 ++
 src/test/run_config2command_tests.pl          |  47 +++
 src/test/run_qemu_img_convert_tests.pl        |  59 +++
 src/test/snapshot-test.pm                     |   4 +-
 23 files changed, 634 insertions(+), 49 deletions(-)
 create mode 100644 src/test/cfg2cmd/simple-backingchain.conf
 create mode 100644 src/test/cfg2cmd/simple-backingchain.conf.cmd


-- 
2.39.5




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