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dm table: fix 'all_blk_mq' inconsistency when an empty table is loaded

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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@sandisk.com>
Tested-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mike Snitzer 2016-11-23 13:51:09 -05:00 committed by Greg Kroah-Hartman
parent 67b0069a51
commit 470b6910f7
1 changed files with 13 additions and 6 deletions

19
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);