From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs: fix allocation length overflow in xfs_bmapi_write()
Date: Fri, 2 Dec 2011 06:24:31 -0500 [thread overview]
Message-ID: <20111202112431.GA17319@infradead.org> (raw)
In-Reply-To: <1322738660-31102-1-git-send-email-david@fromorbit.com>
On Thu, Dec 01, 2011 at 10:24:20PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> When testing the new xfstests --large-fs option that does very large
> file preallocations, this assert was tripped deep in
> xfs_alloc_vextent():
>
> XFS: Assertion failed: args->minlen <= args->maxlen, file: fs/xfs/xfs_alloc.c, line: 2239
>
> The allocation was trying to allocate a zero length extent because
> the lower 32 bits of the allocation length was zero. The remaining
> length of the allocation to be done was an exact multiple of 2^32 -
> the first case I saw was at 496TB remaining to be allocated.
>
> This turns out to be an overflow when converting the allocation
> length (a 64 bit quantity) into the extent length to allocate (a 32
> bit quantity), and it requires the length to be allocated an exact
> multiple of 2^32 blocks to trip the assert.
>
> Fix it by limiting the extent lenth to allocate to MAXEXTLEN.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
(and probably another 3.2 candidate)
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prev parent reply other threads:[~2011-12-02 11:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-01 11:24 [PATCH] xfs: fix allocation length overflow in xfs_bmapi_write() Dave Chinner
2011-12-01 22:00 ` Ben Myers
2011-12-02 11:24 ` Christoph Hellwig [this message]
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