sysfs: fix error handling in binattr write()

Error handling in fs/sysfs/bin.c:write() was wrong because size_t
count is used to receive return value from flush_write() which is
negative on failure.

This patch updates write() such that int variable is used instead.
read() is updated the same way for consistency.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

fs/sysfs/bin.c

@@ -33,16 +33,13 @@ fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
 }
 
 static ssize_t
-read(struct file * file, char __user * userbuf, size_t count, loff_t * off)
+read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
 {
 	char *buffer = file->private_data;
 	struct dentry *dentry = file->f_path.dentry;
 	int size = dentry->d_inode->i_size;
 	loff_t offs = *off;
-	int ret;
+	int count = min_t(size_t, bytes, PAGE_SIZE);
-
-	if (count > PAGE_SIZE)
-		count = PAGE_SIZE;
 
 	if (size) {
 		if (offs > size)
@@ -51,15 +48,14 @@ read(struct file * file, char __user * userbuf, size_t count, loff_t * off)
 			count = size - offs;
 	}
 
-	ret = fill_read(dentry, buffer, offs, count);
+	count = fill_read(dentry, buffer, offs, count);
-	if (ret < 0) 
+	if (count < 0)
-		return ret;
+		return count;
-	count = ret;
 
 	if (copy_to_user(userbuf, buffer, count))
 		return -EFAULT;
 
-	pr_debug("offs = %lld, *off = %lld, count = %zd\n", offs, *off, count);
+	pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
 
 	*off = offs + count;
 
@@ -78,16 +74,15 @@ flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
 	return attr->write(kobj, buffer, offset, count);
 }
 
-static ssize_t write(struct file * file, const char __user * userbuf,
+static ssize_t write(struct file *file, const char __user *userbuf,
-		     size_t count, loff_t * off)
+		     size_t bytes, loff_t *off)
 {
 	char *buffer = file->private_data;
 	struct dentry *dentry = file->f_path.dentry;
 	int size = dentry->d_inode->i_size;
 	loff_t offs = *off;
+	int count = min_t(size_t, bytes, PAGE_SIZE);
 
-	if (count > PAGE_SIZE)
-		count = PAGE_SIZE;
 	if (size) {
 		if (offs > size)
 			return 0;