On Fri, Dec 16, 2016 at 09:25:44AM +0100, Christoph Hellwig wrote:
> On Fri, Dec 16, 2016 at 11:28:51AM +1100, Dave Chinner wrote:
> > > + /*
> > > + * Clamp maxlen to the amount of free space available for the actual
> > > + * extent allocation.
> > > + */
> > > + if (available < (int)args->maxlen && !(flags & XFS_ALLOC_FLAG_CHECK)) {
> > > + args->maxlen = available;
> > > + ASSERT(args->maxlen > 0);
> > > + }
> >
> > I'd love to get rid of all these (int) casts, too...
>
> The problem here is that we compare 32-bit signed to 32-bit unsigned
> variables. And given that this is ripe for nasty bugs due to the C
> type promotion rules I'd rather be extra careful.
Yes, I know - it's bitten me several times in the past. The
underlying problem (IMO) is using xfs_extlen_t for things that
aren't physical BMBT extent lengths, which are bound to:
#define MAXEXTLEN ((xfs_extlen_t)0x001fffff) /* 21 bits */
but it's grown to be used for everything that needs to store or
operate on the length of an extent.
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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