nfsd: filecache: use list_lru_walk_node() in nfsd_file_gc()

list_lru_walk() is only useful when the aim is to remove all elements
from the list_lru.  It will repeatedly visit rotated elements of the
first per-node sublist before proceeding to subsequent sublists.

This patch changes nfsd_file_gc() to use list_lru_walk_node() and
list_lru_count_node() on each NUMA node.

Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: neilbrown

fs/nfsd/filecache.c

@@ -537,11 +537,16 @@ nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru,
 static void
 nfsd_file_gc(void)
 {
+	unsigned long ret = 0;
 	LIST_HEAD(dispose);
-	unsigned long ret;
+	int nid;
+
+	for_each_node_state(nid, N_NORMAL_MEMORY) {
+		unsigned long nr = list_lru_count_node(&nfsd_file_lru, nid);
 
-	ret = list_lru_walk(&nfsd_file_lru, nfsd_file_lru_cb,
-			    &dispose, list_lru_count(&nfsd_file_lru));
+		ret += list_lru_walk_node(&nfsd_file_lru, nid, nfsd_file_lru_cb,
+					  &dispose, &nr);
+	}
 	trace_nfsd_file_gc_removed(ret, list_lru_count(&nfsd_file_lru));
 	nfsd_file_dispose_list_delayed(&dispose);
 }