From 6936c12cf809850180b24947271b8f068fdb15e9 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Wed, 23 Nov 2016 13:51:09 -0500 Subject: [PATCH] dm table: fix 'all_blk_mq' inconsistency when an empty table is loaded 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") Cc: stable@vger.kernel.org # 4.8+ Reported-by: Bart Van Assche Tested-by: Bart Van Assche Signed-off-by: Mike Snitzer --- drivers/md/dm-table.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index c4b53b332607..53b817b29134 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -924,12 +924,6 @@ static int dm_table_determine_type(struct dm_table *t) 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);