static int btt_map_read()

in btt.c [151:205]

• 45 lines of code
• 9 McCabe index (conditional complexity)

static int btt_map_read(struct arena_info *arena, u32 lba, u32 *mapping,
			int *trim, int *error, unsigned long rwb_flags)
{
	int ret;
	__le32 in;
	u32 raw_mapping, postmap, ze, z_flag, e_flag;
	u64 ns_off = arena->mapoff + (lba * MAP_ENT_SIZE);

	if (unlikely(lba >= arena->external_nlba))
		dev_err_ratelimited(to_dev(arena),
			"%s: lba %#x out of range (max: %#x)\n",
			__func__, lba, arena->external_nlba);

	ret = arena_read_bytes(arena, ns_off, &in, MAP_ENT_SIZE, rwb_flags);
	if (ret)
		return ret;

	raw_mapping = le32_to_cpu(in);

	z_flag = ent_z_flag(raw_mapping);
	e_flag = ent_e_flag(raw_mapping);
	ze = (z_flag << 1) + e_flag;
	postmap = ent_lba(raw_mapping);

	/* Reuse the {z,e}_flag variables for *trim and *error */
	z_flag = 0;
	e_flag = 0;

	switch (ze) {
	case 0:
		/* Initial state. Return postmap = premap */
		*mapping = lba;
		break;
	case 1:
		*mapping = postmap;
		e_flag = 1;
		break;
	case 2:
		*mapping = postmap;
		z_flag = 1;
		break;
	case 3:
		*mapping = postmap;
		break;
	default:
		return -EIO;
	}

	if (trim)
		*trim = z_flag;
	if (error)
		*error = e_flag;

	return ret;
}