static void virtio_mem_online_page()

in virtio_mem.c [1233:1290]

• 36 lines of code
• 7 McCabe index (conditional complexity)

static void virtio_mem_online_page(struct virtio_mem *vm,
				   struct page *page, unsigned int order)
{
	const unsigned long start = page_to_phys(page);
	const unsigned long end = start + PFN_PHYS(1 << order);
	unsigned long addr, next, id, sb_id, count;
	bool do_online;

	/*
	 * We can get called with any order up to MAX_ORDER - 1. If our
	 * subblock size is smaller than that and we have a mixture of plugged
	 * and unplugged subblocks within such a page, we have to process in
	 * smaller granularity. In that case we'll adjust the order exactly once
	 * within the loop.
	 */
	for (addr = start; addr < end; ) {
		next = addr + PFN_PHYS(1 << order);

		if (vm->in_sbm) {
			id = virtio_mem_phys_to_mb_id(addr);
			sb_id = virtio_mem_phys_to_sb_id(vm, addr);
			count = virtio_mem_phys_to_sb_id(vm, next - 1) - sb_id + 1;

			if (virtio_mem_sbm_test_sb_plugged(vm, id, sb_id, count)) {
				/* Fully plugged. */
				do_online = true;
			} else if (count == 1 ||
				   virtio_mem_sbm_test_sb_unplugged(vm, id, sb_id, count)) {
				/* Fully unplugged. */
				do_online = false;
			} else {
				/*
				 * Mixture, process sub-blocks instead. This
				 * will be at least the size of a pageblock.
				 * We'll run into this case exactly once.
				 */
				order = ilog2(vm->sbm.sb_size) - PAGE_SHIFT;
				do_online = virtio_mem_sbm_test_sb_plugged(vm, id, sb_id, 1);
				continue;
			}
		} else {
			/*
			 * If the whole block is marked fake offline, keep
			 * everything that way.
			 */
			id = virtio_mem_phys_to_bb_id(vm, addr);
			do_online = virtio_mem_bbm_get_bb_state(vm, id) !=
				    VIRTIO_MEM_BBM_BB_FAKE_OFFLINE;
		}

		if (do_online)
			generic_online_page(pfn_to_page(PFN_DOWN(addr)), order);
		else
			virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,
						    false);
		addr = next;
	}
}