fs: fix kernel_write prototype

Make the position an in/out argument like all the other read/write
helpers and and make the buf argument a void pointer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/read_write.c b/fs/read_write.c
index 9cf1de8..9f3aeb1 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -512,8 +512,8 @@ ssize_t __kernel_write(struct file *file, const char *buf, size_t count, loff_t
 }
 EXPORT_SYMBOL(__kernel_write);
 
-ssize_t kernel_write(struct file *file, const char *buf, size_t count,
-			    loff_t pos)
+ssize_t kernel_write(struct file *file, const void *buf, size_t count,
+			    loff_t *pos)
 {
 	mm_segment_t old_fs;
 	ssize_t res;
@@ -521,7 +521,7 @@ ssize_t kernel_write(struct file *file, const char *buf, size_t count,
 	old_fs = get_fs();
 	set_fs(get_ds());
 	/* The cast to a user pointer is valid due to the set_fs() */
-	res = vfs_write(file, (__force const char __user *)buf, count, &pos);
+	res = vfs_write(file, (__force const char __user *)buf, count, pos);
 	set_fs(old_fs);
 
 	return res;