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authorMikulas Patocka <mpatocka@redhat.com>2010-08-12 04:14:26 +0100
committerAlasdair G Kergon <agk@redhat.com>2010-08-12 04:14:26 +0100
commit7b76ec11fec40203836b488496d2df082d5b2022 (patch)
tree8b3c75295945f0533206c699139e55a30bcd426e /drivers/md
parenta79245b3e5669dc203fec63644d988c451fe55d5 (diff)
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dm stripe: support discards
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> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-stripe.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 1559fdfd2073..c297f6da91ea 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -176,6 +176,7 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
ti->split_io = chunk_size;
ti->num_flush_requests = stripes;
+ ti->num_discard_requests = stripes;
sc->chunk_shift = ffs(chunk_size) - 1;
sc->chunk_mask = ((sector_t) chunk_size) - 1;
@@ -230,6 +231,39 @@ static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
*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)
{
@@ -243,6 +277,11 @@ static int stripe_map(struct dm_target *ti, struct bio *bio,
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);