[dm-devel] [PATCH v2 0/8] multipath-tools: no_path_retry/queue_if_no_path logic

[Martin Wilck]

This patch set attempts to sanitize the logic used for consistently handling
options that can be set both via the "features" string and explicit multipath.conf
options. This is most prominently "no_path_retry" vs. "queue_if_no_path", but also
"retain_attached_hw_handler" vs. the feature of the same name.

The logic this patch set follows is:
 - If "no_path_retry" is set to any value, "queue_if_no_path" is ignored
   (this is the case nowadays for almost all "real" storage arrays, thanks to hwtable).
 - Otherwise, if "queue_if_no_path" is set, treat it like "no_path_retry queue".

... likewise for "retain_attached_hw_handler".

In the long run, we should get rid of the "features" settings duplicating
configuration options altogether; the patch set prepares this by printing
warning messages.

The logic is implemented in the new function reconcile_features_with_options,
which is called from both select_features() and merge_hwe(). In setup_map(),
we need to call select_features() after select_no_path_retry() to make this work.
The actual feature setting for device-mapper is made in assemble_map(), the
patch set also fixes the logic there.

The patch set documents the behavior in the man page, and adds some more
man page fixes.

Finally, by skipping superfluous default initializations in load_config(), the
log messages for the respective config settings become more appropriate.

Review and comments are highly welcome.

Changes wrt v1:
  - Suggestions from Ben Marzinski:
    * Made sure "multipathd show config" still works (1/8).
    * Fixed logging for default setting of "max_sectors" (1/8)
    * Consistent internal treatment of mp->features (3/8, 4/8)
    * Fixed whitespace error (6/8)
    * Added deprecated warnings (8/8)
  - Made sure the same logic is used in propsel.c and config.c by
    calling the same function (3/8, 4/8)
  - Added deprecated warnings (8/8)

Martin Wilck (8):
  libmultipath: load_config: skip setting unnecessary defaults
  libmultipath: add/remove_feature: use const char* for feature
  libmultipath: clarify option conflicts for "features"
  libmultipath: merge_hwe: fix queue_if_no_path logic
  libmultipath: assemble_map: fix queue_if_no_path logic
  multipath.conf.5: document no_path_retry vs. queue_if_no_path
  multipath.conf.5: Remove ??? and other minor fixes
  libmultipath: add deprecated warning for some features settings

 libmultipath/config.c      | 36 +++++++--------------
 libmultipath/configure.c   |  4 +--
 libmultipath/dict.c        | 11 ++++---
 libmultipath/dmparser.c    |  5 ++-
 libmultipath/propsel.c     | 79 +++++++++++++++++++++++++++++++++++++---------
 libmultipath/propsel.h     |  3 ++
 libmultipath/structs.c     | 30 ++++++++++--------
 libmultipath/structs.h     |  4 +--
 multipath/multipath.conf.5 | 52 ++++++++++++++++--------------
 9 files changed, 136 insertions(+), 88 deletions(-)

-- 
2.13.1