[dm-devel] [PATCH 1.5/2] dm-stripe: optimize sector division
Mike Snitzer
snitzer at redhat.com
Wed Jul 28 13:53:33 UTC 2010
Looking closer I'm seeing something odd:
On Tue, Jul 27 2010 at 6:12pm -0400,
Mikulas Patocka <mpatocka at redhat.com> wrote:
> @@ -212,7 +217,11 @@ static void stripe_map_sector(struct str
> {
> sector_t offset = sector - sc->ti->begin;
> sector_t chunk = offset >> sc->chunk_shift;
> - *stripe = sector_div(chunk, sc->stripes);
> + if (likely(sc->stripes_shift >= 0))
> + *stripe = chunk & ((1 << sc->stripes_shift) - 1),
> + chunk >>= sc->stripes_shift;
What's going on here with the comma? Shouldn't it be a semi-colon? And
if so we need curly-braces around the if (likely...).
> + else
> + *stripe = sector_div(chunk, sc->stripes);
> *result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);
> }
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