res_counter: delete res_counter_write()

Since commit 628f42355389 ("memcg: limit change shrink usage") both
res_counter_write() and write_strategy_fn have been unused.  This patch
deletes them both.

Signed-off-by: Greg Thelen <gthelen@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/res_counter.h

@@ -74,14 +74,9 @@ ssize_t res_counter_read(struct res_counter *counter, int member,
 		const char __user *buf, size_t nbytes, loff_t *pos,
 		int (*read_strategy)(unsigned long long val, char *s));
 
-typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
-
 int res_counter_memparse_write_strategy(const char *buf,
 					unsigned long long *res);
 
-int res_counter_write(struct res_counter *counter, int member,
-		      const char *buffer, write_strategy_fn write_strategy);
-
 /*
  * the field descriptors. one for each member of res_counter
  */

kernel/res_counter.c

@@ -192,25 +192,3 @@ int res_counter_memparse_write_strategy(const char *buf,
 	*res = PAGE_ALIGN(*res);
 	return 0;
 }
-
-int res_counter_write(struct res_counter *counter, int member,
-		      const char *buf, write_strategy_fn write_strategy)
-{
-	char *end;
-	unsigned long flags;
-	unsigned long long tmp, *val;
-
-	if (write_strategy) {
-		if (write_strategy(buf, &tmp))
-			return -EINVAL;
-	} else {
-		tmp = simple_strtoull(buf, &end, 10);
-		if (*end != '\0')
-			return -EINVAL;
-	}
-	spin_lock_irqsave(&counter->lock, flags);
-	val = res_counter_member(counter, member);
-	*val = tmp;
-	spin_unlock_irqrestore(&counter->lock, flags);
-	return 0;
-}