On Wed, Feb 26, 2014 at 12:29:22PM -0600, Eric Sandeen wrote:
> On 2/25/14, 8:11 PM, Christoph Hellwig wrote:
> > On Mon, Feb 24, 2014 at 11:27:35PM -0600, Eric Sandeen wrote:
> >> xfs_set_maxicount() overflowed fairly easily for large filesystems
> >> and large maxicount; we started out by multiplying dblocks by
> >> the percentage, *then* dividing by 100, and never checked for
> >> an overflow. The calculations were also, IMHO, a little hard
> >> to follow.
> >
> > Would be useful to get this test case into xfstests..
>
> Ok so I was going on Dave's assertion about that. ;)
>
> To overflow, we'd need dblocks * 100 to be > 2^64-1:
>
> so dblocks would need to be > (2^64-1)/100
>
> for 4k blocks that's 655 exabytes. Maybe not so possible after all ;)
Until the block count is corrupted by fsfuzzer? ;)
> Dave, maybe just removing the open-code is enough here.
Sure, but I still like the conversion to use mult_frac....
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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