This patch implements the lock comparison function I've been talking
about, and converts one of bcache's locks to use it.

b->write_lock has different locking rules; I'm not sure there's an easy
way to get rid of lockdep_set_novalidate_class for it - but the code has
changed and my memory is foggy. 

I'd like it if we could convert existing uses of *_lock_nested() to this
approach, since it's more rigorous and IMO, much clearer. That'll
require looking at specific use cases, though - the inode lock in
fs/inode.c is the only one I looked at and it's got a lot of nutty stuff
going on.

Kent Overstreet (2):
  lockdep: lock_set_lock_cmp_fn()
  bcache: Convert to lock_cmp_fn

 drivers/md/bcache/btree.c     | 15 ++++++++++-
 drivers/md/bcache/btree.h     |  4 +--
 include/linux/lockdep.h       |  8 ++++++
 include/linux/lockdep_types.h |  6 +++++
 kernel/locking/lockdep.c      | 51 ++++++++++++++++++++++++++++++++++-
 5 files changed, 80 insertions(+), 4 deletions(-)

-- 
2.39.2