From: Dave Chinner <david@fromorbit.com>
To: xfs@oss.sgi.com
Subject: [PATCH 29/32] libxfs: work around do_div() not handling 32 bit numerators
Date: Mon, 30 Sep 2013 13:15:41 +1000 [thread overview]
Message-ID: <1380510944-8571-30-git-send-email-david@fromorbit.com> (raw)
In-Reply-To: <1380510944-8571-1-git-send-email-david@fromorbit.com>
From: Dave Chinner <dchinner@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. The kernel code
handles 32 bit numerators just fine, so this patch is a temporary
workaround in the dquot buffer code until we fix do_div() to handle
32 bit numerators correctly.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
libxfs/xfs_dquot_buf.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/libxfs/xfs_dquot_buf.c b/libxfs/xfs_dquot_buf.c
index 620d9d3..ce6b09c 100644
--- a/libxfs/xfs_dquot_buf.c
+++ b/libxfs/xfs_dquot_buf.c
@@ -18,18 +18,28 @@
*/
#include "xfs.h"
+/*
+ * XXX: the userspace implementation of the do_div() macro does not handle 32
+ * bit numerators properly as it passes it by reference as a pointer to a 64 bit
+ * variable and dereferences it as such. Hence the result is way, way off
+ * because it uses 32 bits of garbage for the upper 32 bits of the numerator.
+ *
+ * This is being left here as a reminder that we need to fix do_div() in
+ * userspace as every time we do a libxfs kernel/userspace diff we'll see this
+ * comment.
+ */
int
xfs_calc_dquots_per_chunk(
struct xfs_mount *mp,
unsigned int nbblks) /* basic block units */
{
- unsigned int ndquots;
+ uint64_t ndquots;
ASSERT(nbblks > 0);
ndquots = BBTOB(nbblks);
do_div(ndquots, sizeof(xfs_dqblk_t));
- return ndquots;
+ return (int)ndquots;
}
/*
--
1.8.3.2
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next prev parent reply other threads:[~2013-09-30 3:15 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1380510944-8571-1-git-send-email-david@fromorbit.com>
2013-09-30 3:15 ` [PATCH 01/32] xfsprogs: fix automatic dependency generation Dave Chinner
2013-10-08 23:00 ` Eric Sandeen
2013-09-30 3:15 ` [PATCH 02/32] libxfs: fix missing filetype updates to xfs_dir2.c Dave Chinner
2013-10-08 22:53 ` Eric Sandeen
2013-10-09 20:41 ` Dave Chinner
2013-10-18 16:45 ` Rich Johnston
2013-09-30 3:15 ` [PATCH 03/32] xfs: fix some minor sparse warnings Dave Chinner
2013-10-08 22:56 ` Eric Sandeen
2013-10-09 20:43 ` Dave Chinner
2013-09-30 3:15 ` [PATCH 04/32] xfs: check magic numbers in dir3 leaf verifier first Dave Chinner
2013-10-08 23:03 ` Eric Sandeen
2013-10-09 20:45 ` Dave Chinner
2013-10-09 20:50 ` Eric Sandeen
2013-09-30 3:15 ` [PATCH 05/32] xfs: ensure we copy buffer type in da btree root splits Dave Chinner
2013-10-08 23:06 ` Eric Sandeen
2013-10-18 16:49 ` Rich Johnston
2013-09-30 3:15 ` [PATCH 06/32] xfs: don't assert fail on bad inode numbers Dave Chinner
2013-10-08 23:09 ` Eric Sandeen
2013-09-30 3:15 ` [PATCH 07/32] xfs: dirent dtype presence is dependent on directory magic numbers Dave Chinner
2013-10-08 23:30 ` Eric Sandeen
2013-10-09 20:51 ` Dave Chinner
2013-10-09 20:57 ` Eric Sandeen
2013-10-18 22:38 ` Rich Johnston
2013-09-30 3:15 ` [PATCH 08/32] xfs: create a shared header file for format-related information Dave Chinner
2013-10-08 23:37 ` Eric Sandeen
2013-10-18 16:59 ` Rich Johnston
2013-10-18 22:40 ` Dave Chinner
2013-10-18 22:43 ` Rich Johnston
2013-10-22 18:07 ` Rich Johnston
2013-09-30 3:15 ` [PATCH 09/32] xfs: unify directory/attribute format definitions Dave Chinner
2013-10-14 20:44 ` Eric Sandeen
2013-10-18 20:32 ` Rich Johnston
2013-10-22 22:25 ` Dave Chinner
2013-09-30 3:15 ` [PATCH 10/32] xfs: split dquot buffer operations out Dave Chinner
2013-09-30 3:15 ` [PATCH 11/32] xfs: decouple inode and bmap btree header files Dave Chinner
2013-09-30 3:15 ` [PATCH 12/32] libxfs: unify xfs_btree.c with kernel code Dave Chinner
2013-09-30 3:15 ` [PATCH 13/32] libxfs: bmap btree owner swap support Dave Chinner
2013-09-30 3:15 ` [PATCH 14/32] libxfs: xfs_rtalloc.c becomes xfs_rtbitmap.c Dave Chinner
2013-09-30 3:15 ` [PATCH 15/32] libxfs: bring across inode buffer readahead verifier changes Dave Chinner
2013-09-30 3:15 ` [PATCH 16/32] libxfs: Minor cleanup and bug fix sync Dave Chinner
2013-09-30 3:15 ` [PATCH 17/32] db: separate out straight buffer IO from map based IO Dave Chinner
2013-09-30 3:15 ` [PATCH 18/32] db: rewrite bbmap to use xfs_buf_map Dave Chinner
2013-09-30 3:15 ` [PATCH 19/32] db: rewrite IO engine to use libxfs Dave Chinner
2013-09-30 3:15 ` [PATCH 20/32] db: introduce verifier support into set_cur Dave Chinner
2013-09-30 3:15 ` [PATCH 21/32] db: indicate if the CRC on a buffer is correct or not Dave Chinner
2013-09-30 3:15 ` [PATCH 22/32] db: verify and calculate inode CRCs Dave Chinner
2013-09-30 3:15 ` [PATCH 23/32] db: verify and calculate dquot CRCs Dave Chinner
2013-09-30 3:15 ` [PATCH 24/32] db: add a special directory buffer verifier Dave Chinner
2013-09-30 3:15 ` [PATCH 25/32] db: add a special attribute " Dave Chinner
2013-09-30 3:15 ` [PATCH 26/32] db: re-enable write support for v5 filesystems Dave Chinner
2013-09-30 3:15 ` [PATCH 27/32] libxfs: fix root inode handling inconsistencies Dave Chinner
2013-09-30 3:15 ` [PATCH 28/32] xfs_db: avoid libxfs buffer lookup warnings Dave Chinner
2013-09-30 3:15 ` Dave Chinner [this message]
2013-09-30 3:15 ` [PATCH 30/32] db: enable metadump on CRC filesystems Dave Chinner
2013-09-30 3:15 ` [PATCH 31/32] xfs: support larger inode clusters on v5 filesystems Dave Chinner
2013-09-30 3:15 ` [PATCH 32/32] xfsprogs: kill experimental warnings for " Dave Chinner
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