[dm-devel] [PATCH 0/3] consistent behavior of filter_property()

[mwilck at suse.com]

From: Martin Wilck <mwilck at suse.com>

This is a spring-off of the previous discussion under the subject
"libmultipath: fix NULL dereference in get_be64".

Repeating part of the text of my last post there:

pp->uid_attribute may be set from the hwtable, which
means that vendor/product must be known, which in turn means that
uid_attribute can't be set correctly before sysfs_pathinfo() is run.
Thus, in order to be consistent, we need to move the filter_property()
further down in pathinfo(), after the call to sysfs_pathinfo(). 

However, that has a side effect. As Ben already stated,
pp->uid_attribute currently is *never* set the first time the call
chain pathinfo()->filter_property() is run. After the proposed change,
it would *always* be set in this call chain, possibly leading to more
cases where pathinfo returns PATHINFO_SKIPPED.

This matters e.g. for "multipath -w". When we remove a WWID, we must
be sure get_refwwid() fills in the wwid, which won't happen if
PATHINFO_SKIPPED is returned.

(While looking at this, I discovered that it didn't work in current
upstream either. I guess it has been broken since 0.6.0, or
355291b ("libmultipath: filter for missing property in get_refwwid()"
This lead to the addition of patch 3/3).

In order not to break such use cases, we need to make the
filter_property() test in pathinfo() dependent on DI_BLACKLIST. That
would make a lot of sense, but it'd cause a semantic change.

Comments welcome.

Regards
Martin


Martin Wilck (3):
  pathinfo: call filter_property() after sysfs_pathinfo()
  libmultipath: pathinfo: call filter_property only with DI_BLACKLIST
  multipath -w: allow removing blacklisted paths

 libmultipath/configure.c |  4 +-
 libmultipath/discovery.c | 19 +++++++--
 libmultipath/valid.c     |  4 --
 tests/Makefile           |  2 +-
 tests/test-lib.c         | 18 ++++----
 tests/valid.c            | 91 ++++++++++++++++++++++++++++++++++++----
 6 files changed, 111 insertions(+), 27 deletions(-)

-- 
2.29.2