dm: remove support for stacking dm-mq on .request_fn device(s)
Remove all fiddley code that propped up this support for a blk-mq
request-queue ontop of all .request_fn devices.
Testing has proven this niche request-based dm-mq mode to be buggy, when
testing fault tolerance with DM multipath, and there is no point trying
to preserve it.
Should help improve efficiency of pure dm-mq code and make code
maintenance less delicate.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 3ddaa11..7259eeba 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -418,7 +418,10 @@
spin_unlock_irq(&m->lock);
if (clone) {
- /* Old request-based interface: allocated clone is passed in */
+ /*
+ * Old request-based interface: allocated clone is passed in.
+ * Used by: .request_fn stacked on .request_fn path(s).
+ */
clone->q = bdev_get_queue(bdev);
clone->rq_disk = bdev->bd_disk;
clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;