4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mike Snitzer <snitzer@xxxxxxxxxx>
commit 6936c12cf809850180b24947271b8f068fdb15e9 upstream.
An earlier DM multipath table could have been build ontop of underlying
devices that were all using blk-mq. In that case, if that active
multipath table is replaced with an empty DM multipath table (that
reflects all paths have failed) then it is important that the
'all_blk_mq' state of the active table is transfered to the new empty DM
table. Otherwise dm-rq.c:dm_old_prep_tio() will incorrectly clone a
request that isn't needed by the DM multipath target when it is to issue
IO to an underlying blk-mq device.
Fixes: e83068a5 ("dm mpath: add optional "queue_mode" feature")
Reported-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Tested-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-table.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -924,12 +924,6 @@ static int dm_table_determine_type(struc
BUG_ON(!request_based); /* No targets in this table */
- if (list_empty(devices) && __table_type_request_based(live_md_type)) {
- /* inherit live MD type */
- t->type = live_md_type;
- return 0;
- }
-
/*
* The only way to establish DM_TYPE_MQ_REQUEST_BASED is by
* having a compatible target use dm_table_set_type.
@@ -948,6 +942,19 @@ verify_rq_based:
return -EINVAL;
}
+ if (list_empty(devices)) {
+ int srcu_idx;
+ struct dm_table *live_table = dm_get_live_table(t->md, &srcu_idx);
+
+ /* inherit live table's type and all_blk_mq */
+ if (live_table) {
+ t->type = live_table->type;
+ t->all_blk_mq = live_table->all_blk_mq;
+ }
+ dm_put_live_table(t->md, srcu_idx);
+ return 0;
+ }
+
/* Non-request-stackable devices can't be used for request-based dm */
list_for_each_entry(dd, devices, list) {
struct request_queue *q = bdev_get_queue(dd->dm_dev->bdev);
--
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