Function swaponsomething

freebsd/vm/swap_pager.c:2367–2423

}

static void
swaponsomething(struct vnode *vp, void *id, u_long nblks,
    sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags)
{
	struct swdevt *sp, *tsp;
	daddr_t dvbase;

	/*
	 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
	 * First chop nblks off to page-align it, then convert.
	 *
	 * sw->sw_nblks is in page-sized chunks now too.
	 */
	nblks &= ~(ctodb(1) - 1);
	nblks = dbtoc(nblks);

	sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO);
	sp->sw_blist = blist_create(nblks, M_WAITOK);
	sp->sw_vp = vp;
	sp->sw_id = id;
	sp->sw_dev = dev;
	sp->sw_nblks = nblks;
	sp->sw_used = 0;
	sp->sw_strategy = strategy;
	sp->sw_close = close;
	sp->sw_flags = flags;

	/*
	 * Do not free the first blocks in order to avoid overwriting
	 * any bsd label at the front of the partition
	 */
	blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE),
	    nblks - howmany(BBSIZE, PAGE_SIZE));

	dvbase = 0;
	mtx_lock(&sw_dev_mtx);
	TAILQ_FOREACH(tsp, &swtailq, sw_list) {
		if (tsp->sw_end >= dvbase) {
			/*
			 * We put one uncovered page between the devices
			 * in order to definitively prevent any cross-device
			 * I/O requests
			 */
			dvbase = tsp->sw_end + 1;
		}
	}
	sp->sw_first = dvbase;
	sp->sw_end = dvbase + nblks;
	TAILQ_INSERT_TAIL(&swtailq, sp, sw_list);
	nswapdev++;
	swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE);
	swap_total += nblks;
	swapon_check_swzone();
	swp_sizecheck();
	mtx_unlock(&sw_dev_mtx);
	EVENTHANDLER_INVOKE(swapon, sp);
}