FDB_ASYNC
fdb->fd_state |= FDB_ASYNC;
((fdb->fd_state & FDB_ASYNC) || !(fdb->fd_state & FDB_SYNC))) ||
((fdb->fd_state & FDB_SYNC) || !(fdb->fd_state & FDB_ASYNC))));
fdb->fd_state |= b_flags & B_ASYNC ? FDB_ASYNC : FDB_SYNC;
ASSERT((fdb->fd_state & FDB_ASYNC && fdb->fd_iofunc != NULL) ||
ASSERT(fdb->fd_state & FDB_ASYNC);
isasync = fdb->fd_state & FDB_ASYNC;