[PATCH] md: fix calculation for size of filemap_attr array in md/bitmap
If 'num_pages' were ever 1 more than a multiple of 8 (32bit platforms)
or of 16 (64 bit platforms). filemap_attr would be allocated one
'unsigned long' shorter than required. We need a round-up in there.
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 5554ada..e61e0ef 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -863,9 +863,7 @@
/* We need 4 bits per page, rounded up to a multiple of sizeof(unsigned long) */
bitmap->filemap_attr = kzalloc(
- (((num_pages*4/8)+sizeof(unsigned long)-1)
- /sizeof(unsigned long))
- *sizeof(unsigned long),
+ roundup( DIV_ROUND_UP(num_pages*4, 8), sizeof(unsigned long)),
GFP_KERNEL);
if (!bitmap->filemap_attr)
goto out;