Function aio_daemon

freebsd/kern/vfs_aio.c:1066–1167

* The AIO daemon, most of the actual work is done in aio_process_*, * but the setup (and address space mgmt) is done in this routine. */

 * but the setup (and address space mgmt) is done in this routine.
 */
static void
aio_daemon(void *_id)
{
	struct kaiocb *job;
	struct aioproc *aiop;
	struct kaioinfo *ki;
	struct proc *p;
	struct vmspace *myvm;
	struct thread *td = curthread;
	int id = (intptr_t)_id;

	/*
	 * Grab an extra reference on the daemon's vmspace so that it
	 * doesn't get freed by jobs that switch to a different
	 * vmspace.
	 */
	p = td->td_proc;
	myvm = vmspace_acquire_ref(p);

	KASSERT(p->p_textvp == NULL, ("kthread has a textvp"));

	/*
	 * Allocate and ready the aio control info.  There is one aiop structure
	 * per daemon.
	 */
	aiop = uma_zalloc(aiop_zone, M_WAITOK);
	aiop->aioproc = p;
	aiop->aioprocflags = 0;

	/*
	 * Wakeup parent process.  (Parent sleeps to keep from blasting away
	 * and creating too many daemons.)
	 */
	sema_post(&aio_newproc_sem);

	mtx_lock(&aio_job_mtx);
	for (;;) {
		/*
		 * Take daemon off of free queue
		 */
		if (aiop->aioprocflags & AIOP_FREE) {
			TAILQ_REMOVE(&aio_freeproc, aiop, list);
			aiop->aioprocflags &= ~AIOP_FREE;
		}

		/*
		 * Check for jobs.
		 */
		while ((job = aio_selectjob(aiop)) != NULL) {
			mtx_unlock(&aio_job_mtx);

			ki = job->userproc->p_aioinfo;
			job->handle_fn(job);

			mtx_lock(&aio_job_mtx);
			/* Decrement the active job count. */
			ki->kaio_active_count--;
		}