With commit f363e45f we replaced a bunch of hacky workqueue mutual
exclusion logic with the WQ_NON_REENTRANT flag. One pieces of fallout is
that the exponential backoff breaks in certain cases:
* con_work attempts to connect.
* we get an immediate failure, and the socket state change handler queues
immediate work.
* con_work calls con_fault, we decide to back off, but can't queue delayed
work.
In this case, we add a BACKOFF bit to make con_work reschedule delayed work
next time it runs (which should be immediately).
Signed-off-by: Sage Weil <sage@newdream.net>
60bf8bf881