Abstract sector translation in dm-stripe

Abstract sector -> stripe, sector translation to a function.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
drivers/md/dm-stripe.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

Index: linux-2.6.35-rc6-fast/drivers/md/dm-stripe.c
================================================== =================
--- linux-2.6.35-rc6-fast.orig/drivers/md/dm-stripe.c 2010-07-27 22:43:40.000000000 +0200
+++ linux-2.6.35-rc6-fast/drivers/md/dm-stripe.c 2010-07-27 23:08:28.000000000 +0200
@@ -207,11 +207,19 @@ static void stripe_dtr(struct dm_target
kfree(sc);
}

+static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
+ uint32_t *stripe, sector_t *result)
+{
+ sector_t offset = sector - sc->ti->begin;
+ sector_t chunk = offset >> sc->chunk_shift;
+ *stripe = sector_div(chunk, sc->stripes);
+ *result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);
+}
+
static int stripe_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
struct stripe_c *sc = (struct stripe_c *) ti->private;
- sector_t offset, chunk;
uint32_t stripe;

if (unlikely(bio_empty_barrier(bio))) {
@@ -220,13 +228,11 @@ static int stripe_map(struct dm_target *
return DM_MAPIO_REMAPPED;
}

- offset = bio->bi_sector - ti->begin;
- chunk = offset >> sc->chunk_shift;
- stripe = sector_div(chunk, sc->stripes);
+ stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);

+ bio->bi_sector += sc->stripe[stripe].physical_start;
bio->bi_bdev = sc->stripe[stripe].dev->bdev;
- bio->bi_sector = sc->stripe[stripe].physical_start +
- (chunk << sc->chunk_shift) + (offset & sc->chunk_mask);
+
return DM_MAPIO_REMAPPED;
}


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