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

To:	Dave Chinner <david@xxxxxxxxxxxxx>
Subject:	Re: [PATCH 30/37] libxfs: work around do_div() not handling 32 bit numerators
From:	Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date:	Thu, 7 Nov 2013 12:54:54 -0800
Cc:	xfs@xxxxxxxxxxx
Delivered-to:	xfs@xxxxxxxxxxx
In-reply-to:	<1383700043-32305-31-git-send-email-david@xxxxxxxxxxxxx>
References:	<1383700043-32305-1-git-send-email-david@xxxxxxxxxxxxx> <1383700043-32305-31-git-send-email-david@xxxxxxxxxxxxx>
User-agent:	Mutt/1.5.21 (2010-09-15)

On Wed, Nov 06, 2013 at 12:07:16PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> 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@xxxxxxxxxx>

Looks good,

Reviewed-by: Christoph Hellwig <hch@xxxxxx>

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Re: [PATCH 36/37] repair: Increase default repair parallelism on large filesystems, (continued) Re: [PATCH 36/37] repair: Increase default repair parallelism on large filesystems, Christoph Hellwig Re: [PATCH 36/37] repair: Increase default repair parallelism on large filesystems, Dave Chinner Re: [PATCH 36/37] repair: Increase default repair parallelism on large filesystems, Dave Chinner Re: [PATCH 36/37] repair: Increase default repair parallelism on large filesystems, Christoph Hellwig [PATCH 21/37] db: introduce verifier support into set_cur, Dave Chinner [PATCH 35/37] repair: prefetching is turned off unnecessarily, Dave Chinner Re: [PATCH 35/37] repair: prefetching is turned off unnecessarily, Christoph Hellwig [PATCH 27/37] db: re-enable write support for v5 filesystems., Dave Chinner [PATCH 23/37] db: verify and calculate inode CRCs, Dave Chinner [PATCH 30/37] libxfs: work around do_div() not handling 32 bit numerators, Dave Chinner Re: [PATCH 30/37] libxfs: work around do_div() not handling 32 bit numerators, Christoph Hellwig <= [PATCH 19/37] libxfs: refactor libxfs_buf_read_map for xfs_db, Dave Chinner Re: [PATCH 19/37] libxfs: refactor libxfs_buf_read_map for xfs_db, Christoph Hellwig [PATCH 28/37] xfs_db: avoid libxfs buffer lookup warnings, Dave Chinner Re: [PATCH 28/37] xfs_db: avoid libxfs buffer lookup warnings, Dave Chinner Re: [PATCH 28/37] xfs_db: avoid libxfs buffer lookup warnings, Christoph Hellwig [PATCH 31/37] db: Unwind the IO stack on exit, Dave Chinner Re: [PATCH 31/37] db: Unwind the IO stack on exit, Christoph Hellwig [PATCH 25/37] db: add a special directory buffer verifier, Dave Chinner [PATCH 22/37] db: indicate if the CRC on a buffer is correct or not, Dave Chinner [PATCH 18/37] db: rewrite bbmap to use xfs_buf_map, Dave Chinner

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