dm: fold dm_process_bio() into dm_submit_bio()

dm_process_bio() is only called by dm_submit_bio(), there is no benefit
to keeping dm_process_bio() factored out, so fold it.

While at it, cleanup dm_submit_bio()'s DMF_BLOCK_IO_FOR_SUSPEND related
branching and expand scope of dm_get_live_table() rcu reference on map
via common 'out' label to dm_put_live_table().
Signed-off-by: NMike Snitzer <snitzer@redhat.com>

drivers/md/dm.c

@@ -1665,28 +1665,6 @@ static blk_qc_t __process_bio(struct mapped_device *md, struct dm_table *map,
 	return ret;
 }
 
-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;
-
-	if (unlikely(!map)) {
-		bio_io_error(bio);
-		return ret;
-	}
-
-	/*
-	 * Use blk_queue_split() for abnormal IO (e.g. discard, writesame, etc)
-	 * otherwise associated queue_limits won't be imposed.
-	 */
-	if (is_abnormal_io(bio))
-		blk_queue_split(&bio);
-
-	if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED)
-		return __process_bio(md, map, bio);
-	return __split_and_process_bio(md, map, bio);
-}
-
 static blk_qc_t dm_submit_bio(struct bio *bio)
 {
 	struct mapped_device *md = bio->bi_disk->private_data;
@@ -1707,22 +1685,36 @@ static blk_qc_t dm_submit_bio(struct bio *bio)
 	}
 
 	map = dm_get_live_table(md, &srcu_idx);
+	if (unlikely(!map)) {
+		DMERR_LIMIT("%s: mapping table unavailable, erroring io",
+			    dm_device_name(md));
+		bio_io_error(bio);
+		goto out;
+	}
 
-	/* if we're suspended, we have to queue this io for later */
+	/* If suspended, queue this IO for later */
 	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
-		dm_put_live_table(md, srcu_idx);
-
 		if (bio->bi_opf & REQ_NOWAIT)
 			bio_wouldblock_error(bio);
-		else if (!(bio->bi_opf & REQ_RAHEAD))
-			queue_io(md, bio);
-		else
+		else if (bio->bi_opf & REQ_RAHEAD)
 			bio_io_error(bio);
-		return ret;
+		else
+			queue_io(md, bio);
+		goto out;
 	}
 
-	ret = dm_process_bio(md, map, bio);
+	/*
+	 * Use blk_queue_split() for abnormal IO (e.g. discard, writesame, etc)
+	 * otherwise associated queue_limits won't be imposed.
+	 */
+	if (is_abnormal_io(bio))
+		blk_queue_split(&bio);
 
+	if (dm_get_md_type(md) == DM_TYPE_NVME_BIO_BASED)
+		ret = __process_bio(md, map, bio);
+	else
+		ret = __split_and_process_bio(md, map, bio);
+out:
 	dm_put_live_table(md, srcu_idx);
 	return ret;
 }