dm: push md->immutable_target optimization down to __process_bio()

Also, update associated stale comment in __bind().

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 82886b4..e1cb3b9 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1680,7 +1680,7 @@ static blk_qc_t __split_and_process_bio(struct mapped_device *md,
  * fact that targets that use it do _not_ have a need to split bios.
  */
 static blk_qc_t __process_bio(struct mapped_device *md, struct dm_table *map,
-                             struct bio *bio, struct dm_target *ti)
+                             struct bio *bio)
 {
        struct clone_info ci;
        blk_qc_t ret = BLK_QC_T_NONE;
@@ -1705,6 +1705,12 @@ static blk_qc_t __process_bio(struct mapped_device *md, struct dm_table *map,
                /* dec_pending submits any data associated with flush */
        } else {
                struct dm_target_io *tio;
+               struct dm_target *ti = md->immutable_target;
+
+               if (WARN_ON_ONCE(!ti)) {
+                       error = -EIO;
+                       goto out;
+               }
 
                ci.bio = bio;
                ci.sector_count = bio_sectors(bio);
@@ -1724,21 +1730,12 @@ static blk_qc_t dm_process_bio(struct mapped_device *md,
                               struct dm_table *map, struct bio *bio)
 {
        blk_qc_t ret = BLK_QC_T_NONE;
-       struct dm_target *ti = md->immutable_target;
 
        if (unlikely(!map)) {
                bio_io_error(bio);
                return ret;
        }
 
-       if (!ti) {
-               ti = dm_table_find_target(map, bio->bi_iter.bi_sector);
-               if (unlikely(!ti)) {
-                       bio_io_error(bio);
-                       return ret;
-               }
-       }
-
        /*
         * If in ->submit_bio we need to use blk_queue_split(), otherwise
         * queue_limits for abnormal requests (e.g. discard, writesame, etc)
@@ -1753,7 +1750,7 @@ static blk_qc_t dm_process_bio(struct mapped_device *md,
        }
 
        if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED)
-               return __process_bio(md, map, bio, ti);
+               return __process_bio(md, map, bio);
        return __split_and_process_bio(md, map, bio);
 }
 
@@ -2120,8 +2117,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
                /*
                 * Leverage the fact that request-based DM targets and
                 * NVMe bio based targets are immutable singletons
-                * - used to optimize both dm_request_fn and dm_mq_queue_rq;
-                *   and __process_bio.
+                * - used to optimize both __process_bio and dm_mq_queue_rq
                 */
                md->immutable_target = dm_table_get_immutable_target(t);
        }