Stateid's hold a read reference for a read open, a write reference for a
write open, and an additional one of each for each read+write open. The
latter wasn't getting put on a downgrade, so something like:
open RW
open R
downgrade to R
was resulting in a file leak.
Also fix an imbalance in an error path.
Regression from 7d94784293 "nfsd4: fix
downgrade/lock logic".
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
f197c27196