fput: Don't reinvent the wheel but use existing llist API

Although llist provides proper APIs, they are not used. Make them used.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/file_table.c

@@ -233,12 +233,10 @@ static LLIST_HEAD(delayed_fput_list);
 static void delayed_fput(struct work_struct *unused)
 {
 	struct llist_node *node = llist_del_all(&delayed_fput_list);
-	struct llist_node *next;
+	struct file *f, *t;
 
-	for (; node; node = next) {
-		next = llist_next(node);
-		__fput(llist_entry(node, struct file, f_u.fu_llist));
-	}
+	llist_for_each_entry_safe(f, t, node, f_u.fu_llist)
+		__fput(f);
 }
 
 static void ____fput(struct callback_head *work)
@@ -312,7 +310,7 @@ void put_filp(struct file *file)
 }
 
 void __init files_init(void)
-{ 
+{
 	filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
 			SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
 	percpu_counter_init(&nr_files, 0, GFP_KERNEL);
@@ -331,4 +329,4 @@ void __init files_maxfiles_init(void)
 	n = ((totalram_pages - memreserve) * (PAGE_SIZE / 1024)) / 10;
 
 	files_stat.max_files = max_t(unsigned long, n, NR_FILE);
-} 
+}