lock
struct rw_semaphore lock;
down_read(&tree->u.lock);
up_read(&tree->u.lock);
down_write(&tree->u.lock);
up_write(&tree->u.lock);
down_write(&lh->cache->trees[index].u.lock);
down_read(&lh->cache->trees[index].u.lock);
up_write(&lh->cache->trees[index].u.lock);
up_read(&lh->cache->trees[index].u.lock);
struct mutex *lock);
static bool lock(void *unused)
struct lock {