resource_size_t nd_pmem_available_dpa()

in dimm_devs.c [914:973]

• 48 lines of code
• 13 McCabe index (conditional complexity)

resource_size_t nd_pmem_available_dpa(struct nd_region *nd_region,
		struct nd_mapping *nd_mapping, resource_size_t *overlap)
{
	resource_size_t map_start, map_end, busy = 0, available, blk_start;
	struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
	struct resource *res;
	const char *reason;
	unsigned long align;

	if (!ndd)
		return 0;

	align = dpa_align(nd_region);
	if (!align)
		return 0;

	map_start = nd_mapping->start;
	map_end = map_start + nd_mapping->size - 1;
	blk_start = max(map_start, map_end + 1 - *overlap);
	for_each_dpa_resource(ndd, res) {
		resource_size_t start, end;

		start = ALIGN_DOWN(res->start, align);
		end = ALIGN(res->end + 1, align) - 1;
		if (start >= map_start && start < map_end) {
			if (strncmp(res->name, "blk", 3) == 0)
				blk_start = min(blk_start,
						max(map_start, start));
			else if (end > map_end) {
				reason = "misaligned to iset";
				goto err;
			} else
				busy += end - start + 1;
		} else if (end >= map_start && end <= map_end) {
			if (strncmp(res->name, "blk", 3) == 0) {
				/*
				 * If a BLK allocation overlaps the start of
				 * PMEM the entire interleave set may now only
				 * be used for BLK.
				 */
				blk_start = map_start;
			} else
				busy += end - start + 1;
		} else if (map_start > start && map_start < end) {
			/* total eclipse of the mapping */
			busy += nd_mapping->size;
			blk_start = map_start;
		}
	}

	*overlap = map_end + 1 - blk_start;
	available = blk_start - map_start;
	if (busy < available)
		return ALIGN_DOWN(available - busy, align);
	return 0;

 err:
	nd_dbg_dpa(nd_region, ndd, res, "%s\n", reason);
	return 0;
}