On Friday 21 January 2005 3:20 pm, Roland Dreier wrote: > Kevin> We have to take a mod of the chunk value and the number of > Kevin> stripes (which can be a non-power-of-2, so a shift won't > Kevin> work). It's been my understanding that you couldn't mod a > Kevin> 64-bit value with a 32-bit value in the kernel. > > If I understand you correctly, do_div() (defined in <asm/div64.h>) > does what you need. Look at asm-generic/div64.h for a good > description of the precise semantics of do_div().
Thanks for the tip, Roland. That seems to be exactly what we needed. Here's a different version of Alasdair's patch that changes chunk to 64-bit and uses do_div(). -- Kevin Corry [EMAIL PROTECTED] http://evms.sourceforge.net/ In stripe_map(), change chunk to 64-bit and use do_div to divide and mod by the number of stripes. --- diff/drivers/md/dm-stripe.c 2005-01-21 15:55:02.093379864 -0600 +++ source/drivers/md/dm-stripe.c 2005-01-21 15:54:25.400957960 -0600 @@ -173,9 +173,8 @@ struct stripe_c *sc = (struct stripe_c *) ti->private; sector_t offset = bio->bi_sector - ti->begin; - uint32_t chunk = (uint32_t) (offset >> sc->chunk_shift); - uint32_t stripe = chunk % sc->stripes; /* 32bit modulus */ - chunk = chunk / sc->stripes; + sector_t chunk = offset >> sc->chunk_shift; + uint32_t stripe = do_div(chunk, sc->stripes); bio->bi_bdev = sc->stripe[stripe].dev->bdev; bio->bi_sector = sc->stripe[stripe].physical_start + @@ -210,7 +209,7 @@ static struct target_type stripe_target = { .name = "striped", - .version= {1, 0, 1}, + .version= {1, 0, 2}, .module = THIS_MODULE, .ctr = stripe_ctr, .dtr = stripe_dtr, - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
