[PATCH v2 qemu-server 0/5] bypass host page cache for restore on zvol

[Christian Ebner <c.ebner@proxmox.com>]

This patch series skips writing to the host page cache for restores
to zvols, with the intention to avoid potential I/O delay issues for
other ZFS-backed VMs during page writeback on certain setups, as
reported in enterprise support and reproduced internally.

This patch series adds an optional no-cache parameter for pbs-restore
command invocation, setting the BDRV_O_NOCACHE flag for the block
device being restored to and sets `cache=none` for vma restores.

Since this seems to affect only zvol's, conditionally set the flag only
during restores to storages with type `zfspool`.

pve-qemu:

Christian Ebner (1):
  add optional no-cache flag to bypass host page cache on pbs-restore

 ...no-cache-flag-to-skip-host-page-cach.patch | 64 +++++++++++++++++++
 debian/patches/series                         |  1 +
 2 files changed, 65 insertions(+)
 create mode 100644 debian/patches/pve/0047-pbs-restore-add-no-cache-flag-to-skip-host-page-cach.patch

qemu-server:

Christian Ebner (4):
  helpers: optionally get package version for kvm_user_version()
  helpers: add helper for min package version comparison
  pbs-restore: set 'no-cache' on block devices backed by zfspool
  vma restore: skip page cache on block devices backed by zfspool

 src/PVE/QemuServer.pm         | 25 +++++++++++++++++++++-
 src/PVE/QemuServer/Helpers.pm | 40 ++++++++++++++++++++++++++++-------
 2 files changed, 56 insertions(+), 9 deletions(-)

-- 
2.47.3