Use the fl_lmops field to identify which locks are ours, instead of trying to
look them up in our private hash.  This is safer and more efficient.

Earlier versions of this patch used a lock flag instead, but Trond pointed out
that adding a new flag for each lock manager wasn't going to scale well, and
suggested this approach instead; a separate patch converts lockd to using
fl_lmops in the same way.

In the NFSv4 case this looks like a bit of a hack, since the NFSv4 server
isn't currently actually defining a lock_manager_operations struct, so we end
up defining one *just* to serve as a cookie to identify our locks.

But it works, and we actually do expect to start using the
lock_manager_operations at some point anyway.
Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Andy Adamson <andros@citi.umich.edu>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>