locks: add a new "lm_owner_key" lock operation
authorJeff Layton <jlayton@redhat.com>
Fri, 21 Jun 2013 12:58:19 +0000 (08:58 -0400)
committerAl Viro <viro@zeniv.linux.org.uk>
Sat, 29 Jun 2013 08:57:45 +0000 (12:57 +0400)
commit3999e49364193f7dbbba66e2be655fe91ba1fced
tree5971637ac3b15d5d72797d4050ee35216b9fede1
parent48f74186546cd5929397856eab209ebcb5692d11
locks: add a new "lm_owner_key" lock operation

Currently, the hashing that the locking code uses to add these values
to the blocked_hash is simply calculated using fl_owner field. That's
valid in most cases except for server-side lockd, which validates the
owner of a lock based on fl_owner and fl_pid.

In the case where you have a small number of NFS clients doing a lot
of locking between different processes, you could end up with all
the blocked requests sitting in a very small number of hash buckets.

Add a new lm_owner_key operation to the lock_manager_operations that
will generate an unsigned long to use as the key in the hashtable.
That function is only implemented for server-side lockd, and simply
XORs the fl_owner and fl_pid.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Documentation/filesystems/Locking
fs/lockd/svclock.c
fs/locks.c
include/linux/fs.h