libceph: avoid dropping con mutex before fault
(cherry picked from commit
8636ea672f0c5ab7478c42c5b6705ebd1db7eb6a)
The ceph_fault() function takes the con mutex, so we should avoid
dropping it before calling it. This fixes a potential race with
another thread calling ceph_con_close(), or _open(), or similar (we
don't reverify con->state after retaking the lock).
Add annotation so that lockdep realizes we will drop the mutex before
returning.
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>