uml: use simple_write_to_buffer()

Simplify write file operation for mmapper by using
simple_write_to_buffer().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 7 deletions

diff --git a/arch/um/drivers/mmapper_kern.c b/arch/um/drivers/mmapper_kern.c
index 6bc73f0e8e29..7e0619c2c2c6 100644
--- a/arch/um/drivers/mmapper_kern.c
+++ b/arch/um/drivers/mmapper_kern.c
@@ -37,13 +37,7 @@ static ssize_t mmapper_write(struct file *file, const char __user *buf,
         if (*ppos > mmapper_size)
                 return -EINVAL;
 
-        if (count > mmapper_size - *ppos)
-                count = mmapper_size - *ppos;
-
-        if (copy_from_user(&v_buf[*ppos], buf, count))
-                return -EFAULT;
-
-        return count;
+        return simple_write_to_buffer(v_buf, mmapper_size, ppos, buf, count);
 }
 
 static long mmapper_ioctl(struct file *file, unsigned int cmd, unsigned long arg)