[PATCH] md: fix calculation for size of filemap_attr array in md/bitmap
authorNeil Brown <neilb@suse.de>
Thu, 12 Apr 2007 06:28:44 +0000 (23:28 -0700)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Thu, 12 Apr 2007 22:31:42 +0000 (15:31 -0700)
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>
drivers/md/bitmap.c

index 5554adaa58f9be01d37bc5623f63384c084e69de..e61e0efe9ec71db54a91916d978ecbda05ec1314 100644 (file)
@@ -863,9 +863,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 
        /* 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;