NLM/NFS: Use cached nlm_host when calling nlmclnt_proc()

Now that each NFS mount point caches its own nlm_host structure, it can be
passed to nlmclnt_proc() for each lock request.  By pinning an nlm_host for
each mount point, we trade the overhead of looking up or creating a fresh
nlm_host struct during every NLM procedure call for a little extra memory.

We also restrict the nlmclnt_proc symbol to limit the use of this call to
in-tree modules.

Note that nlm_lookup_host() (just removed from the client's per-request
NLM processing) could also trigger an nlm_host garbage collection.  Now
client-side nlm_host garbage collection occurs only during NFS mount
processing.  Since the NFS client now holds a reference on these nlm_host
structures, they wouldn't have been affected by garbage collection
anyway.

Given that nlm_lookup_host() reorders the global nlm_host chain after
every successful lookup, and that a garbage collection could be triggered
during the call, we've removed a significant amount of per-NLM-request
CPU processing overhead.

Sidebar: there are only a few remaining references to the internals of
NFS inodes in the client-side NLM code.  The only references I found are
related to extracting or comparing the inode's file handle via NFS_FH().
One is in nlmclnt_grant(); the other is in nlmclnt_setlockargs().

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
index ad5402f5456b..73368075af03 100644
--- a/include/linux/lockd/bind.h
+++ b/include/linux/lockd/bind.h
@@ -42,7 +42,8 @@ extern struct nlm_host *nlmclnt_init(const char *server_name,
 					u32 nfs_version);
 extern void	nlmclnt_done(struct nlm_host *host);
 
-extern int	nlmclnt_proc(struct inode *, int, struct file_lock *);
+extern int	nlmclnt_proc(struct nlm_host *host, int cmd,
+					struct file_lock *fl);
 extern int	lockd_up(int proto);
 extern void	lockd_down(void);