[Devel] [PATCH hci-8.1 v2 0/4] dm-ploop: fix acknowledged writes lost when discard and allocation share a BAT writeback

[Konstantin Khorenko]

Hi Den,

the patches look good to me, no changes needed.

While reviewing them I found a few problems nearby, all older than the
series:

- A failed cluster copy on grow leaves MD_UPDATING and MD_DIRTY set on
  the BAT page. After the resume every allocating write, discard or COW
  on that page waits in wait_llist forever.
  https://virtuozzo.atlassian.net/browse/VSTOR-152981

- ploop_suspend_submitting_pios() does not wait for the allocator
  thread, which can read a deltas[] slot being vacated by a merge and
  oops on a NULL file or truncate the top image. 2/4 adds the same
  memset as notify_delta_merged() to merge_latest, so the window now
  exists there too.
  https://virtuozzo.atlassian.net/browse/VSTOR-152984

- ploop_submit_embedded_pio() checks stop_submitting_pios without
  deferred_lock, so a pio can slip past the suspend of submission or
  get stuck in llsuspended_pios after the resume.
  https://virtuozzo.atlassian.net/browse/VSTOR-152985

--
Best regards,
Konstantin