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Go Back   Linux Archive > Redhat > Device-mapper Development

 
 
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Old 07-28-2010, 12:03 AM
Mike Snitzer
 
Default dm stripe: enable discard support

The DM core will submit a discard bio to the stripe target for each
stripe in a striped DM device. The stripe target will determine
stripe-specific portions of the supplied bio to be remapped into
individual (at most 'num_discard_requests' extents). If a given
stripe-specific discard bio doesn't touch a particular stripe the bio
will be dropped.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
drivers/md/dm-stripe.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)

Index: linux-2.6-block/drivers/md/dm-stripe.c
================================================== =================
--- linux-2.6-block.orig/drivers/md/dm-stripe.c
+++ linux-2.6-block/drivers/md/dm-stripe.c
@@ -167,6 +167,7 @@ static int stripe_ctr(struct dm_target *
sc->stripe_width = width;
ti->split_io = chunk_size;
ti->num_flush_requests = stripes;
+ ti->num_discard_requests = stripes;

sc->chunk_mask = ((sector_t) chunk_size) - 1;
for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
@@ -216,6 +217,39 @@ static void stripe_map_sector(struct str
*result = (chunk << sc->chunk_shift) | (offset & sc->chunk_mask);
}

+static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
+ uint32_t target_stripe, sector_t *result)
+{
+ uint32_t stripe;
+
+ stripe_map_sector(sc, sector, &stripe, result);
+ if (stripe == target_stripe)
+ return;
+ *result &= ~sc->chunk_mask; /* round down */
+ if (target_stripe < stripe)
+ *result += sc->chunk_mask + 1; /* next chunk */
+}
+
+static int stripe_map_discard(struct stripe_c *sc, struct bio *bio,
+ uint32_t target_stripe)
+{
+ sector_t begin, end;
+
+ stripe_map_range_sector(sc, bio->bi_sector, target_stripe, &begin);
+ stripe_map_range_sector(sc, bio->bi_sector + bio_sectors(bio),
+ target_stripe, &end);
+ if (begin < end) {
+ bio->bi_bdev = sc->stripe[target_stripe].dev->bdev;
+ bio->bi_sector = begin + sc->stripe[target_stripe].physical_start;
+ bio->bi_size = to_bytes(end - begin);
+ return DM_MAPIO_REMAPPED;
+ } else {
+ /* The range doesn't map to the target stripe */
+ bio_endio(bio, 0);
+ return DM_MAPIO_SUBMITTED;
+ }
+}
+
static int stripe_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
@@ -229,6 +263,11 @@ static int stripe_map(struct dm_target *
bio->bi_bdev = sc->stripe[target_request_nr].dev->bdev;
return DM_MAPIO_REMAPPED;
}
+ if (unlikely(bio->bi_rw & REQ_DISCARD)) {
+ target_request_nr = map_context->target_request_nr;
+ BUG_ON(target_request_nr >= sc->stripes);
+ return stripe_map_discard(sc, bio, target_request_nr);
+ }

stripe_map_sector(sc, bio->bi_sector, &stripe, &bio->bi_sector);


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Old 07-28-2010, 12:06 AM
Mike Snitzer
 
Default dm stripe: enable discard support

Alasdair,

I forgot to use the following in the patch header:

From: Mikulas Patocka <mpatocka@redhat.com>

please adjust, thanks!

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