static sense_reason_t spc_emulate_modesense()

in target_core_spc.c [1017:1140]

• 82 lines of code
• 24 McCabe index (conditional complexity)

static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd)
{
	struct se_device *dev = cmd->se_dev;
	char *cdb = cmd->t_task_cdb;
	unsigned char buf[SE_MODE_PAGE_BUF], *rbuf;
	int type = dev->transport->get_device_type(dev);
	int ten = (cmd->t_task_cdb[0] == MODE_SENSE_10);
	bool dbd = !!(cdb[1] & 0x08);
	bool llba = ten ? !!(cdb[1] & 0x10) : false;
	u8 pc = cdb[2] >> 6;
	u8 page = cdb[2] & 0x3f;
	u8 subpage = cdb[3];
	int length = 0;
	int ret;
	int i;

	memset(buf, 0, SE_MODE_PAGE_BUF);

	/*
	 * Skip over MODE DATA LENGTH + MEDIUM TYPE fields to byte 3 for
	 * MODE_SENSE_10 and byte 2 for MODE_SENSE (6).
	 */
	length = ten ? 3 : 2;

	/* DEVICE-SPECIFIC PARAMETER */
	if (cmd->se_lun->lun_access_ro || target_lun_is_rdonly(cmd))
		spc_modesense_write_protect(&buf[length], type);

	/*
	 * SBC only allows us to enable FUA and DPO together.  Fortunately
	 * DPO is explicitly specified as a hint, so a noop is a perfectly
	 * valid implementation.
	 */
	if (target_check_fua(dev))
		spc_modesense_dpofua(&buf[length], type);

	++length;

	/* BLOCK DESCRIPTOR */

	/*
	 * For now we only include a block descriptor for disk (SBC)
	 * devices; other command sets use a slightly different format.
	 */
	if (!dbd && type == TYPE_DISK) {
		u64 blocks = dev->transport->get_blocks(dev);
		u32 block_size = dev->dev_attrib.block_size;

		if (ten) {
			if (llba) {
				length += spc_modesense_long_blockdesc(&buf[length],
								       blocks, block_size);
			} else {
				length += 3;
				length += spc_modesense_blockdesc(&buf[length],
								  blocks, block_size);
			}
		} else {
			length += spc_modesense_blockdesc(&buf[length], blocks,
							  block_size);
		}
	} else {
		if (ten)
			length += 4;
		else
			length += 1;
	}

	if (page == 0x3f) {
		if (subpage != 0x00 && subpage != 0xff) {
			pr_warn("MODE_SENSE: Invalid subpage code: 0x%02x\n", subpage);
			return TCM_INVALID_CDB_FIELD;
		}

		for (i = 0; i < ARRAY_SIZE(modesense_handlers); ++i) {
			/*
			 * Tricky way to say all subpage 00h for
			 * subpage==0, all subpages for subpage==0xff
			 * (and we just checked above that those are
			 * the only two possibilities).
			 */
			if ((modesense_handlers[i].subpage & ~subpage) == 0) {
				ret = modesense_handlers[i].emulate(cmd, pc, &buf[length]);
				if (!ten && length + ret >= 255)
					break;
				length += ret;
			}
		}

		goto set_length;
	}

	for (i = 0; i < ARRAY_SIZE(modesense_handlers); ++i)
		if (modesense_handlers[i].page == page &&
		    modesense_handlers[i].subpage == subpage) {
			length += modesense_handlers[i].emulate(cmd, pc, &buf[length]);
			goto set_length;
		}

	/*
	 * We don't intend to implement:
	 *  - obsolete page 03h "format parameters" (checked by Solaris)
	 */
	if (page != 0x03)
		pr_err("MODE SENSE: unimplemented page/subpage: 0x%02x/0x%02x\n",
		       page, subpage);

	return TCM_UNKNOWN_MODE_PAGE;

set_length:
	if (ten)
		put_unaligned_be16(length - 2, buf);
	else
		buf[0] = length - 1;

	rbuf = transport_kmap_data_sg(cmd);
	if (rbuf) {
		memcpy(rbuf, buf, min_t(u32, SE_MODE_PAGE_BUF, cmd->data_length));
		transport_kunmap_data_sg(cmd);
	}

	target_complete_cmd_with_length(cmd, SAM_STAT_GOOD, length);
	return 0;
}