nfsd: move the confirmed and unconfirmed hlists to a rbtree

The current code requires that we md5 hash the name in order to store
the client in the confirmed and unconfirmed trees. Change it instead
to store the clients in a pair of rbtrees, and simply compare the
cl_names directly instead of hashing them. This also necessitates that
we add a new flag to the clp->cl_flags field to indicate which tree
the client is currently in.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/state.h

@@ -232,7 +232,7 @@ struct nfsd4_sessionid {
  */
 struct nfs4_client {
 	struct list_head	cl_idhash; 	/* hash by cl_clientid.id */
-	struct list_head	cl_strhash; 	/* hash by cl_name */
+	struct rb_node		cl_namenode;	/* link into by-name trees */
 	struct list_head	cl_openowners;
 	struct idr		cl_stateids;	/* stateid lookup */
 	struct list_head	cl_delegations;
@@ -253,6 +253,7 @@ struct nfs4_client {
 #define NFSD4_CLIENT_CB_KILL		(1)
 #define NFSD4_CLIENT_STABLE		(2)	/* client on stable storage */
 #define NFSD4_CLIENT_RECLAIM_COMPLETE	(3)	/* reclaim_complete done */
+#define NFSD4_CLIENT_CONFIRMED		(4)	/* client is confirmed */
 #define NFSD4_CLIENT_CB_FLAG_MASK	(1 << NFSD4_CLIENT_CB_UPDATE | \
 					 1 << NFSD4_CLIENT_CB_KILL)
 	unsigned long		cl_flags;