Function swp_pager_freeswapspace

freebsd/vm/swap_pager.c:875–902

* SWP_PAGER_FREESWAPSPACE() - free raw swap space * * This routine returns the specified swap blocks back to the bitmap. * * This routine may not sleep. */

 *	This routine may not sleep.
 */
static void
swp_pager_freeswapspace(daddr_t blk, daddr_t npages)
{
	struct swdevt *sp;

	if (npages == 0)
		return;
	mtx_lock(&sw_dev_mtx);
	TAILQ_FOREACH(sp, &swtailq, sw_list) {
		if (swp_pager_isondev(blk, sp)) {
			sp->sw_used -= npages;
			/*
			 * If we are attempting to stop swapping on
			 * this device, we don't want to mark any
			 * blocks free lest they be reused.
			 */
			if ((sp->sw_flags & SW_CLOSING) == 0) {
				blist_free(sp->sw_blist, blk - sp->sw_first,
				    npages);
				swap_pager_avail += npages;
				swp_sizecheck();
			}
			mtx_unlock(&sw_dev_mtx);
			return;
		}
	}
	panic("Swapdev not found");
}

/*
 * SYSCTL_SWAP_FRAGMENTATION() -	produce raw swap space stats