dm mpath: add optional "queue_mode" feature

Allow a user to specify an optional feature 'queue_mode <mode>' where
<mode> may be "bio", "rq" or "mq" -- which corresponds to bio-based,
request_fn rq-based, and blk-mq rq-based respectively.

If the queue_mode feature isn't specified the default for the
"multipath" target is still "rq" but if dm_mod.use_blk_mq is set to Y
it'll default to mode "mq".

This new queue_mode feature introduces the ability for each multipath
device to have its own queue_mode (whereas before this feature all
multipath devices effectively had to have the same queue_mode).

This commit also goes a long way to eliminate the awkward (ab)use of
DM_TYPE_*, the associated filter_md_type() and other relatively fragile
and difficult to maintain code.

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

1 files changed, 1 insertions, 9 deletions

diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index b611b3064a7c..2e0e4a53a312 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -34,14 +34,6 @@
 #define DM_STATUS_NOFLUSH_FLAG		(1 << 0)
 
 /*
- * Type of table and mapped_device's mempool
- */
-#define DM_TYPE_NONE			0
-#define DM_TYPE_BIO_BASED		1
-#define DM_TYPE_REQUEST_BASED		2
-#define DM_TYPE_MQ_REQUEST_BASED	3
-
-/*
  * List of devices that a metadevice uses and should open/close.
  */
 struct dm_dev_internal {
@@ -77,7 +69,7 @@ struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
 struct dm_target *dm_table_get_immutable_target(struct dm_table *t);
 struct dm_target *dm_table_get_wildcard_target(struct dm_table *t);
 bool dm_table_request_based(struct dm_table *t);
-bool dm_table_mq_request_based(struct dm_table *t);
+bool dm_table_all_blk_mq_devices(struct dm_table *t);
 void dm_table_free_md_mempools(struct dm_table *t);
 struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);