[v2,0/5] multipath: fix hang in flush_map_nopaths

Message

Benjamin Marzinski April 25, 2024, 11:35 p.m. UTC

Commit 9bd3482e ("multipathd: make flush_map() delete maps like the
multipath command") fixed a multipathd hang when trying to remove a
multipath device with only kpartx devices opening it but with
outstanding IO. However that commit didn't deal with autoremoving the
multipath device when the last path is deleted. It's possible for the
same hang to occur during an autoremove. Since this remove is not
initiated by the user, multipathd shouldn't just automatically disable
queueing. On the other hand, multipathd hanging is a big problem, since
that stops all of its work on all multipath devices. This patchset
handles the issue by changing the options for flush_on_last_del to give
the users more choice in how to deal with this situation. But none of
the options will allow multipath to flush a device while it is queueing,
which is the action that can cause it to hang.

Differences from v1 (from conversations with Martin Wilck):
0001: Since flush_map_nopaths() will no longer need to know what the
      deferred_remove setting is, only exported partmap_in_use.
0002: Fixed up the commit message. Removed all of the code treating
      deferred removes as special in flush_map_nopaths(), and made
      sure flush_map_nopaths() skipped the autoremove if disabling
      queueing failed.
Original 0003: Dropped. flush_map_nopaths() no longer needs to care
      about the deferred_remove value, so dm_flush_map_nopaths() does.
0003-0005: New commits based on suggestions from Martin

Benjamin Marzinski (5):
  libmultipath: export partmap_in_use
  libmultipath: change flush_on_last_del to fix a multipathd hang
  libmultipath: remove redundant config option from InfiniBox config
  libmultipath: pad dev_loss_tmo to avoid race with no_path_retry
  libmultipath: fix deferred_remove function arguments

 libmultipath/defaults.h           |  2 +-
 libmultipath/devmapper.c          | 21 +++++----
 libmultipath/devmapper.h          |  1 +
 libmultipath/dict.c               | 72 +++++++++++++++++++++++++++----
 libmultipath/dict.h               |  1 +
 libmultipath/discovery.c          |  5 +++
 libmultipath/hwtable.c            |  5 +--
 libmultipath/libmultipath.version |  3 +-
 libmultipath/propsel.c            |  4 +-
 libmultipath/structs.h            |  7 +--
 multipath/multipath.conf.5.in     | 20 ++++++---
 multipathd/main.c                 | 39 +++++++++++++----
 12 files changed, 139 insertions(+), 41 deletions(-)