cgroup files: convert res_counter_write() to be a cgroups write_string() handler

Currently res_counter_write() is a raw file handler even though it's
ultimately taking a number, since in some cases it wants to
pre-process the string when converting it to a number.

This patch converts res_counter_write() from a raw file handler to a
write_string() handler; this allows some of the boilerplate
copying/locking/checking to be removed, and simplies the cleanup path,
since these functions are now performed by the cgroups framework.

[lizf@cn.fujitsu.com: build fix]
Signed-off-by: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 21 insertions, 27 deletions

diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index d3c61b4ebef2..f275c8eca772 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -13,6 +13,7 @@
 #include <linux/slab.h>
 #include <linux/res_counter.h>
 #include <linux/uaccess.h>
+#include <linux/mm.h>
 
 void res_counter_init(struct res_counter *counter)
 {
@@ -102,44 +103,37 @@ u64 res_counter_read_u64(struct res_counter *counter, int member)
 	return *res_counter_member(counter, member);
 }
 
-ssize_t res_counter_write(struct res_counter *counter, int member,
-		const char __user *userbuf, size_t nbytes, loff_t *pos,
-		int (*write_strategy)(char *st_buf, unsigned long long *val))
+int res_counter_memparse_write_strategy(const char *buf,
+					unsigned long long *res)
 {
-	int ret;
-	char *buf, *end;
-	unsigned long flags;
-	unsigned long long tmp, *val;
-
-	buf = kmalloc(nbytes + 1, GFP_KERNEL);
-	ret = -ENOMEM;
-	if (buf == NULL)
-		goto out;
+	char *end;
+	/* FIXME - make memparse() take const char* args */
+	*res = memparse((char *)buf, &end);
+	if (*end != '\0')
+		return -EINVAL;
 
-	buf[nbytes] = '\0';
-	ret = -EFAULT;
-	if (copy_from_user(buf, userbuf, nbytes))
-		goto out_free;
+	*res = PAGE_ALIGN(*res);
+	return 0;
+}
 
-	ret = -EINVAL;
+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;
 
-	strstrip(buf);
 	if (write_strategy) {
-		if (write_strategy(buf, &tmp)) {
-			goto out_free;
-		}
+		if (write_strategy(buf, &tmp))
+			return -EINVAL;
 	} else {
 		tmp = simple_strtoull(buf, &end, 10);
 		if (*end != '\0')
-			goto out_free;
+			return -EINVAL;
 	}
 	spin_lock_irqsave(&counter->lock, flags);
 	val = res_counter_member(counter, member);
 	*val = tmp;
 	spin_unlock_irqrestore(&counter->lock, flags);
-	ret = nbytes;
-out_free:
-	kfree(buf);
-out:
-	return ret;
+	return 0;
 }