Kcopyd uses a semaphore as mutex.  Use the mutex API instead of the (binary)
semaphore,
Signed-off-by: NMatthias Kaehlcke <matthias.kaehlcke@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>