[PATCH] uml: allow ubd devices to provide partial end blocks

If the file backing a ubd device is not an even blocklength, then the last
partial block is now readable, and it is padded with zeros.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/drivers/ubd_kern.c

@@ -682,6 +682,8 @@ static int ubd_new_disk(int major, u64 size, int unit,
 	return 0;
 }
 
+#define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
+
 static int ubd_add(int n)
 {
 	struct ubd *dev = &ubd_dev[n];
@@ -697,6 +699,8 @@ static int ubd_add(int n)
 	if(err < 0)
 		return(err);
 
+	dev->size = ROUND_BLOCK(dev->size);
+
 	err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
 	if(err) 
 		return(err);