[pve-devel] [PATCH common/storage/container] add fsfreeze/thaw for rbd snapshots

[Stoiko Ivanov]

this patchset addresses #2991 and #2528.

As discussed in #2991 (and off-list with Wolfgang B. and Dominik) - it does
not address the fundamental problem of the snapshot being created outside of
the open krbd block-device, by an independend 'rbd' call (which is most likely
the reason for the inconsistency).

However according to the reporter in #2991 it does help in their case to
actually get backups of their containers.

I put the ioctl call inside sync_container_namespace since it:
* should happen shortly after the syncfs call
* needs to happen inside the container's mount namespace (else we'd need to
  mount the filesystem in order to freeze/thaw it - see the proposed patch
  in #2528)

and I wanted to avoid to fork+nsenter for each volume twice (in
__snapshot_create_vol_snapshs_hook)

Would be grateful for feedback if this approach is ok (reading containerconfig
+ storage config in __snapshot_freeze) or if some other way would be nicer.

Tested on my testsetup with a ceph-backed container (and 2 additional
mountpoints (one ceph, one on LVM thin).


pve-common:
Stoiko Ivanov (1):
  add fsfreeze helper:

 src/PVE/Tools.pm | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

pve-storage:
Stoiko Ivanov (1):
  add check for fsfreeze before snapshot

 PVE/Storage.pm           | 12 ++++++++++++
 PVE/Storage/Plugin.pm    |  4 ++++
 PVE/Storage/RBDPlugin.pm |  5 +++++
 3 files changed, 21 insertions(+)

pve-container:
Stoiko Ivanov (1):
  snapshot creation: fsfreeze mountpoints, if needed

 src/PVE/LXC.pm            | 21 +++++++++++++++++----
 src/PVE/LXC/Config.pm     | 15 ++++++++++++++-
 src/test/snapshot-test.pm | 12 +++++++++++-
 3 files changed, 42 insertions(+), 6 deletions(-)

-- 
2.20.1