Function wait_for_completion

block/src/qcow_async.rs:590–603

(async_io: &mut dyn AsyncIo)

    }

    fn wait_for_completion(async_io: &mut dyn AsyncIo) -> (u64, i32) {
        loop {
            if let Some(c) = async_io.next_completed_request() {
                return c;
            }
            // Block until the eventfd is signaled (io_uring or synthetic).
            let fd = async_io.notifier().as_raw_fd();
            let mut val = 0u64;
            // SAFETY: reading 8 bytes from a valid eventfd.
            unsafe {
                libc::read(fd, (&raw mut val).cast(), 8);
            }
        }
    }

    fn async_write(disk: &QcowDisk, offset: u64, data: &[u8]) {
        let mut async_io = disk.create_async_io(1).unwrap();