diff options
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c index efe969074928..bca448e11878 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -829,6 +829,49 @@ static int __split_bio(struct mapped_device *md, struct bio *bio) * CRUD END *---------------------------------------------------------------*/ +static int dm_merge_bvec(struct request_queue *q, + struct bvec_merge_data *bvm, + struct bio_vec *biovec) +{ + struct mapped_device *md = q->queuedata; + struct dm_table *map = dm_get_table(md); + struct dm_target *ti; + sector_t max_sectors; + int max_size; + + if (unlikely(!map)) + return 0; + + ti = dm_table_find_target(map, bvm->bi_sector); + + /* + * Find maximum amount of I/O that won't need splitting + */ + max_sectors = min(max_io_len(md, bvm->bi_sector, ti), + (sector_t) BIO_MAX_SECTORS); + max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size; + if (max_size < 0) + max_size = 0; + + /* + * merge_bvec_fn() returns number of bytes + * it can accept at this offset + * max is precomputed maximal io size + */ + if (max_size && ti->type->merge) + max_size = ti->type->merge(ti, bvm, biovec, max_size); + + /* + * Always allow an entire first page + */ + if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT)) + max_size = biovec->bv_len; + + dm_table_put(map); + + return max_size; +} + /* * The request function that just remaps the bio built up by * dm_merge_bvec. @@ -1032,6 +1075,7 @@ static struct mapped_device *alloc_dev(int minor) blk_queue_make_request(md->queue, dm_request); blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY); md->queue->unplug_fn = dm_unplug_all; + blk_queue_merge_bvec(md->queue, dm_merge_bvec); md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache); if (!md->io_pool) |