drbd: cleanup bogus assert message

This fixes ASSERT( mdev->state.disk == D_FAILED ) in drivers/block/drbd/drbd_main.c

When we detach from local disk, we let the local refcount hit zero twice.

First, we transition to D_FAILED, so we won't give out new references
to incoming requests; we still may give out *internal* references, though.
Once the refcount hits zero [1] while in D_FAILED, we queue a transition
to D_DISKLESS to our worker.  We need to queue it, because we may be in
atomic context when putting the reference.
Once the transition to D_DISKLESS actually happened [2] from worker context,
we don't give out new internal references either.

Between hitting zero the first time [1] and actually transition to
D_DISKLESS [2], there may be a few very short lived internal get/put,
so we may hit zero more than once while being in D_FAILED, or even see a
race where a an internal get_ldev() happened while D_FAILED, but the
corresponding put_ldev() happens just after the transition to D_DISKLESS.

That's why we have the additional test_and_set_bit(GO_DISKLESS,);
and that's why the assert was placed wrong.
Since there was exactly one code path left to drbd_go_diskless(),
and that checks already for D_FAILED, drop that assert,
and fold in the drbd_queue_work().

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 0 insertions, 7 deletions

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index e98da675f0c1..731a28eedc56 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -3252,13 +3252,6 @@ static int w_go_diskless(struct drbd_work *w, int unused)
 	return 0;
 }
 
-void drbd_go_diskless(struct drbd_conf *mdev)
-{
-	D_ASSERT(mdev->state.disk == D_FAILED);
-	if (!test_and_set_bit(GO_DISKLESS, &mdev->flags))
-		drbd_queue_work(&mdev->tconn->sender_work, &mdev->go_diskless);
-}
-
 /**
  * drbd_queue_bitmap_io() - Queues an IO operation on the whole bitmap
  * @mdev:	DRBD device.