[PATCH 30/37] libxfs: work around do_div() not handling 32 bit numerators

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

The libxfs dquot buffer code uses do_div() with a 32 bit numerator.
This gives incorrect results as do_div() passes the numerator by
reference as a pointer to a 64 bit value. Hence it does the division
using 32 bits of garbage gives the wrong result.

As per Christoph's suggestion, we can kill the usage of do_div()
here completely and just do the division directly, both in userspace
and kernel space.

Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 libxfs/xfs_dquot_buf.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/libxfs/xfs_dquot_buf.c b/libxfs/xfs_dquot_buf.c
index 620d9d3..6bbb0ff 100644
--- a/libxfs/xfs_dquot_buf.c
+++ b/libxfs/xfs_dquot_buf.c
@@ -23,13 +23,8 @@ xfs_calc_dquots_per_chunk(
 	struct xfs_mount	*mp,
 	unsigned int		nbblks)	/* basic block units */
 {
-	unsigned int	ndquots;
-
 	ASSERT(nbblks > 0);
-	ndquots = BBTOB(nbblks);
-	do_div(ndquots, sizeof(xfs_dqblk_t));
-
-	return ndquots;
+	return BBTOB(nbblks) / sizeof(xfs_dqblk_t);
 }
 
 /*
-- 
1.8.4.rc3