NFSv4: change nfs4_select_rw_stateid to take a lock_context inplace of lock_owner

The only time that a lock_context is not immediately available is in
setattr, and now that it has an open_context, it can easily find one
with nfs_get_lock_context.
This removes the need for the on-stack nfs_lockowner.

This change is preparation for correctly support flock stateids.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 1452177..6651658 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -457,7 +457,7 @@
 extern void nfs4_put_lock_state(struct nfs4_lock_state *lsp);
 extern int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl);
 extern int nfs4_select_rw_stateid(struct nfs4_state *, fmode_t,
-		const struct nfs_lockowner *, nfs4_stateid *,
+		const struct nfs_lock_context *, nfs4_stateid *,
 		struct rpc_cred **);
 
 extern struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter, gfp_t gfp_mask);