All of lore.kernel.org
 help / color / mirror / Atom feed
From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 27/30] libxfs: work around do_div() not handling 32 bit numerators
Date: Tue, 5 Nov 2013 12:55:53 +1100	[thread overview]
Message-ID: <20131105015553.GW6188@dastard> (raw)
In-Reply-To: <20131104091643.GG23564@infradead.org>

On Mon, Nov 04, 2013 at 01:16:43AM -0800, Christoph Hellwig wrote:
> On Wed, Oct 30, 2013 at 03:31:18PM +1100, Dave Chinner wrote:
> > 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.
> 
> The right fix is to simply stop using do_div here, both in kernel and
> userspace.

Oh, right, I was thinking that BBTOB() resulted in a u64 value like
BTOBB() and BTOBBT() do. It doesn't have a built in cast, so takes
whatever type the source variable has.

> >  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;
> 
> 	ndquots = BBTOB(nbblks) / sizeof(xfs_dqblk_t);

Yup, that should work.

> Also the current xfs_calc_dquots_per_chunk doesn't use the mp argument
> anyway, but all callers do.  I think in the end we'd want to take that
> in from the calers end end up with a version that includes the
> check from the quotainfo.  But for getting userspace up and running my
> above minimal version should do it.

Yes, changed to fix. I'll drive further cleanups from the kernel
side here...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

  reply	other threads:[~2013-11-05  1:56 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-30  4:30 [PATCH 00/30 V3] xfsprogs: CRC write support for xfs_db Dave Chinner
2013-10-30  4:30 ` [PATCH 01/30] xfsprogs: fix automatic dependency generation Dave Chinner
2013-10-31 14:44   ` Christoph Hellwig
2013-10-30  4:30 ` [PATCH 02/30] xfs: fix some minor sparse warnings Dave Chinner
2013-10-31 14:44   ` Christoph Hellwig
2013-10-30  4:30 ` [PATCH 03/30] xfs: create a shared header file for format-related information Dave Chinner
2013-10-31 14:45   ` Christoph Hellwig
2013-10-30  4:30 ` [PATCH 04/30] xfs: split dquot buffer operations out Dave Chinner
2013-10-31 14:45   ` Christoph Hellwig
2013-10-30  4:30 ` [PATCH 05/30] xfs: decouple inode and bmap btree header files Dave Chinner
2013-10-31 14:45   ` Christoph Hellwig
2013-10-30  4:30 ` [PATCH 06/30] libxfs: unify xfs_btree.c with kernel code Dave Chinner
2013-10-31 14:46   ` Christoph Hellwig
2013-10-30  4:30 ` [PATCH 07/30] libxfs: bmap btree owner swap support Dave Chinner
2013-10-31 14:47   ` Christoph Hellwig
2013-10-30  4:30 ` [PATCH 08/30] libxfs: xfs_rtalloc.c becomes xfs_rtbitmap.c Dave Chinner
2013-10-31 14:48   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 09/30] libxfs: bring across inode buffer readahead verifier changes Dave Chinner
2013-10-31 14:48   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 10/30] libxfs: Minor cleanup and bug fix sync Dave Chinner
2013-10-31 14:48   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 11/30] xfs: remove newlines from strings passed to __xfs_printk Dave Chinner
2013-10-31 14:49   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 12/30] xfs: fix the wrong new_size/rnew_size at xfs_iext_realloc_direct() Dave Chinner
2013-10-31 14:49   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 13/30] xfs: fix node forward in xfs_node_toosmall Dave Chinner
2013-10-31 14:49   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 14/30] xfs: don't emit corruption noise on fs probes Dave Chinner
2013-10-31 14:49   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 15/30] db: separate out straight buffer IO from map based IO Dave Chinner
2013-10-31 14:56   ` Christoph Hellwig
2013-10-31 21:50     ` Dave Chinner
2013-11-01 12:51       ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 16/30] db: rewrite bbmap to use xfs_buf_map Dave Chinner
2013-10-31 15:06   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 17/30] db: rewrite IO engine to use libxfs Dave Chinner
2013-10-31 15:10   ` Christoph Hellwig
2013-10-31 21:59     ` Dave Chinner
2013-10-30  4:31 ` [PATCH 18/30] db: introduce verifier support into set_cur Dave Chinner
2013-11-01 13:07   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 19/30] db: indicate if the CRC on a buffer is correct or not Dave Chinner
2013-11-01 13:09   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 20/30] db: verify and calculate inode CRCs Dave Chinner
2013-11-04  9:05   ` Christoph Hellwig
2013-11-05  0:18     ` Dave Chinner
2013-10-30  4:31 ` [PATCH 21/30] db: verify and calculate dquot CRCs Dave Chinner
2013-11-04  9:06   ` Christoph Hellwig
2013-11-05  0:25     ` Dave Chinner
2013-10-30  4:31 ` [PATCH 22/30] db: add a special directory buffer verifier Dave Chinner
2013-11-04  9:07   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 23/30] db: add a special attribute " Dave Chinner
2013-11-04  9:07   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 24/30] db: re-enable write support for v5 filesystems Dave Chinner
2013-11-04  9:07   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 25/30] libxfs: fix root inode handling inconsistencies Dave Chinner
2013-10-30 10:23   ` Christoph Hellwig
2013-10-30 21:59     ` Dave Chinner
2013-10-31  4:13       ` [PATCH 25/30 V2] " Dave Chinner
2013-10-31 15:00         ` Christoph Hellwig
2013-10-31 22:04           ` Dave Chinner
2013-11-01 13:03             ` Christoph Hellwig
2013-11-04 23:22               ` Dave Chinner
2013-11-05  9:05                 ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 26/30] xfs_db: avoid libxfs buffer lookup warnings Dave Chinner
2013-11-04  9:12   ` Christoph Hellwig
2013-11-05  0:52     ` Dave Chinner
2013-11-05  9:06       ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 27/30] libxfs: work around do_div() not handling 32 bit numerators Dave Chinner
2013-11-04  9:16   ` Christoph Hellwig
2013-11-05  1:55     ` Dave Chinner [this message]
2013-10-30  4:31 ` [PATCH 28/30] db: enable metadump on CRC filesystems Dave Chinner
2013-11-04  9:18   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 29/30] xfs: support larger inode clusters on v5 filesystems Dave Chinner
2013-11-04  9:18   ` Christoph Hellwig
2013-10-30  4:31 ` [PATCH 30/30] xfsprogs: kill experimental warnings for " Dave Chinner
2013-11-04  9:19   ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20131105015553.GW6188@dastard \
    --to=david@fromorbit.com \
    --cc=hch@infradead.org \
    --cc=xfs@oss.sgi.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.