[dm-devel] [PATCH v2 00/54] multipath-tools series part IV: identify paths by dev_t

[mwilck at suse.com]

From: Martin Wilck <mwilck at suse.com>

Hi Christophe, hi Ben,

This is part IV of a larger patch series for multipath-tools I've been preparing.
It's based on the previously submitted part III.

The full series will also be available here:
https://github.com/mwilck/multipath-tools/tree/ups/submit-2008
This part is tagged "submit-200812-4".

The dominant idea of the patches in this subseries is to move away from
the device node name as the main path identifier towards the dev_t aka
major/minor number. This is motivated by the fact that dev_t is used by the
kernel device mapper for referring to devices, both maps and paths.
If searching a device by dev_t fails, it's basically certain not to exist.
DM calls with major/minor number may even succeed if the respective devnode
has not been created yet. dev_t also works better for devices that aren't
fully initialized yet. Of course we still track the device name, but mostly
for log messages and user-directed output.

In short, using dev_t as primary identifier makes our code more robust.

The subseries also contains some unrelated fixes for functions I worked on
while making these changes.

Changes v1 -> v2, as suggested by Ben Marzinski:

 * 44/54: "libmultipath: adopt_paths(): don't bail out on single path failure"
    - fail if adding a specific path was requested and failed. 
 * 46/54: "libmultipath: path_discover(): always set DI_BLACKLIST"
    - dropped, replaced by "libmultipath: path_discover(): explain pathinfo flags",
      which contains only comments

NOTE: In my v1 submission, I made a mistake when sending part V, so that
*patch number 54 is present twice* in the full series.
I deliberately didn't correct that this time, to preserve numbering.

Martin Wilck (12):
  libmultipath: adopt_paths(): use find_path_by_devt()
  libmultipath: adopt_paths(): don't bail out on single path failure
  libmultipath: path_discover(): use find_path_by_devt()
  libmultipath: path_discover(): explain pathinfo flags
  libmultipath: get_refwwid(): use find_path_by_devt()
  libmultipath: get_refwwid(): call get_multipath_config() only once
  libmultipath: get_refwwid(): get rid of "check" label
  libmultipath: get_refwwid(): use symbolic return values
  libmultipath: get_refwwid(): use switch statement
  libmultipath: constify get_mpe_wwid()
  multipath: call strchop() on command line argument
  libmultipath: get_refwwid(): skip strchop(), and constify dev
    parameter

 libmultipath/config.c      |   2 +-
 libmultipath/config.h      |   2 +-
 libmultipath/configure.c   | 200 +++++++++++++------------------------
 libmultipath/configure.h   |   2 +-
 libmultipath/discovery.c   |  37 ++++---
 libmultipath/structs_vec.c |  17 ++--
 multipath/main.c           |   2 +
 multipathd/main.c          |   3 +-
 8 files changed, 103 insertions(+), 162 deletions(-)