dm table: train hybrid target type detection to select blk-mq if appropriate
Otherwise replacing the multipath target with the error target fails:
device-mapper: ioctl: can't change device type after initial table load.
The error target was mistakenly considered to be target type
DM_TYPE_REQUEST_BASED rather than DM_TYPE_MQ_REQUEST_BASED even if the
target it was to replace was of type DM_TYPE_MQ_REQUEST_BASED.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 2d7e373..14954d8 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -831,7 +831,7 @@
struct dm_target *tgt;
struct dm_dev_internal *dd;
struct list_head *devices;
- unsigned live_md_type;
+ unsigned live_md_type = dm_get_md_type(t->md);
for (i = 0; i < t->num_targets; i++) {
tgt = t->targets + i;
@@ -855,8 +855,8 @@
* Determine the type from the live device.
* Default to bio-based if device is new.
*/
- live_md_type = dm_get_md_type(t->md);
- if (live_md_type == DM_TYPE_REQUEST_BASED)
+ if (live_md_type == DM_TYPE_REQUEST_BASED ||
+ live_md_type == DM_TYPE_MQ_REQUEST_BASED)
request_based = 1;
else
bio_based = 1;
@@ -870,6 +870,17 @@
BUG_ON(!request_based); /* No targets in this table */
+ /*
+ * Request-based dm supports only tables that have a single target now.
+ * To support multiple targets, request splitting support is needed,
+ * and that needs lots of changes in the block-layer.
+ * (e.g. request completion process for partial completion.)
+ */
+ if (t->num_targets > 1) {
+ DMWARN("Request-based dm doesn't support multiple targets yet");
+ return -EINVAL;
+ }
+
/* Non-request-stackable devices can't be used for request-based dm */
devices = dm_table_get_devices(t);
list_for_each_entry(dd, devices, list) {
@@ -893,20 +904,14 @@
" are blk-mq request-stackable");
return -EINVAL;
}
- }
+ t->type = DM_TYPE_MQ_REQUEST_BASED;
- /*
- * Request-based dm supports only tables that have a single target now.
- * To support multiple targets, request splitting support is needed,
- * and that needs lots of changes in the block-layer.
- * (e.g. request completion process for partial completion.)
- */
- if (t->num_targets > 1) {
- DMWARN("Request-based dm doesn't support multiple targets yet");
- return -EINVAL;
- }
+ } else if (hybrid && list_empty(devices) && live_md_type != DM_TYPE_NONE) {
+ /* inherit live MD type */
+ t->type = live_md_type;
- t->type = !use_blk_mq ? DM_TYPE_REQUEST_BASED : DM_TYPE_MQ_REQUEST_BASED;
+ } else
+ t->type = DM_TYPE_REQUEST_BASED;
return 0;
}