dm table: allow upgrade from bio-based to specialized bio-based variant (c934edad) · Commits · 戴 / test

In practice this is really only meaningful in the context of the DM multipath target (which uses dm_table_set_type() to set the type of device DM should create via its "queue_mode" option). So this change allows a DM multipath device with "queue_mode bio" to be upgraded from DM_TYPE_BIO_BASED to DM_TYPE_NVME_BIO_BASED -- iff the underlying device(s) are NVMe. DM_TYPE_NVME_BIO_BASED is just a DM core implementation detail that allows for NVMe-specific optimizations (e.g. use direct_make_request instead of generic_make_request). If in the future there is no benefit or need to distinguish NVMe vs not: then it will be removed. Signed-off-by:

Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-table.c

+5 −9

Original line number	Diff line number	Diff line
		@@ -942,17 +942,12 @@ static int dm_table_determine_type(struct dm_table *t)

		if (t->type != DM_TYPE_NONE) {
		/* target already set the table's type */
		if (t->type == DM_TYPE_BIO_BASED)
		return 0;
		else if (t->type == DM_TYPE_NVME_BIO_BASED) {
		if (!dm_table_does_not_support_partial_completion(t)) {
		DMERR("nvme bio-based is only possible with devices"
		" that don't support partial completion");
		return -EINVAL;
		}
		/* Fallthru, also verify all devices are blk-mq */
		if (t->type == DM_TYPE_BIO_BASED) {
		/* possibly upgrade to a variant of bio-based */
		goto verify_bio_based;
		}
		BUG_ON(t->type == DM_TYPE_DAX_BIO_BASED);
		BUG_ON(t->type == DM_TYPE_NVME_BIO_BASED);
		goto verify_rq_based;
		}

		@@ -985,6 +980,7 @@ static int dm_table_determine_type(struct dm_table *t)
		}

		if (bio_based) {
		verify_bio_based:
		/* We must use this table as bio-based */
		t->type = DM_TYPE_BIO_BASED;
		if (dm_table_supports_dax(t) \|\|

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