vhost: better variable name in logging

We really store a page offset in write_address,
so rename it write_page to avoid confusion.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/vhost.c

@@ -882,15 +882,15 @@ static int set_bit_to_user(int nr, void __user *addr)
 static int log_write(void __user *log_base,
 		     u64 write_address, u64 write_length)
 {
+	u64 write_page = write_address / VHOST_PAGE_SIZE;
 	int r;
 	if (!write_length)
 		return 0;
 	write_length += write_address % VHOST_PAGE_SIZE;
-	write_address /= VHOST_PAGE_SIZE;
 	for (;;) {
 		u64 base = (u64)(unsigned long)log_base;
-		u64 log = base + write_address / 8;
-		int bit = write_address % 8;
+		u64 log = base + write_page / 8;
+		int bit = write_page % 8;
 		if ((u64)(unsigned long)log != log)
 			return -EFAULT;
 		r = set_bit_to_user(bit, (void __user *)(unsigned long)log);
@@ -899,7 +899,7 @@ static int log_write(void __user *log_base,
 		if (write_length <= VHOST_PAGE_SIZE)
 			break;
 		write_length -= VHOST_PAGE_SIZE;
-		write_address += 1;
+		write_page += 1;
 	}
 	return r;
 }