- fix a 4.6-rc1 bio-based DM 'struct dm_target_io' leak in an error path

- stable@ fix for DM cache metadata's READ_LOCK macros that were
  incorrectly returning error if the block manager was in read-only
  mode; also cleanup multi-statement macros to use do {} while(0)
dm cache metadata: fix READ_LOCK macros and cleanup WRITE_LOCK macros

The READ_LOCK macro was incorrectly returning -EINVAL if
dm_bm_is_read_only() was true -- it will always be true once the cache
metadata transitions to read-only by dm_cache_metadata_set_read_only().

Wrap READ_LOCK and WRITE_LOCK multi-statement macros in do {} while(0).
Also, all accesses of the 'cmd' argument passed to these related macros
are now encapsulated in parenthesis.

A follow-up patch can be developed to eliminate the use of macros in
favor of pure C code.  Avoiding that now given that this needs to apply
to stable@.

Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Fixes: d14fcf3dd79 ("dm cache: make sure every metadata function checks fail_io")
Cc: stable@vger.kernel.org
1 file changed