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)
for 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 059704fbb753ada7df4f97da979071de1cac073a..cef12872508afdc07de5d681a5c517e8f18c8383 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -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;