Commit d4b2b867 authored by Roland Dreier's avatar Roland Dreier Committed by Nicholas Bellinger
Browse files

target: Refactor MODE SENSE emulation 



Convert spc_emulate_modesense() to use a table of mode pages, rather
than a switch statement.  This makes it possible to add more pages
sanely -- in particular we no longer need to make sure we keep the
0x3f (return all mode pages) case in sync.

While we're touching this code, make our MODE SENSE emulation a bit
better in a couple of ways:
 - When the initiator passes PC == 1 asking for changeable values,
   return all 0s to show we don't support setting anything.
 - Return a block descriptor for disk devices.

(nab: fix up device attribute references to use dev->dev_attrib
      in for-next code)

Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 1f981de5

drivers/target/target_core_spc.c

+176 −59
Original line number Diff line number Diff line
@@ -639,18 +639,28 @@ out: 
	return ret;

}



static int spc_modesense_rwrecovery(unsigned char *p)

static int spc_modesense_rwrecovery(struct se_device *dev, u8 pc, u8 *p)

{

	p[0] = 0x01;

	p[1] = 0x0a;



	/* No changeable values for now */

	if (pc == 1)

		goto out;



out:

	return 12;

}



static int spc_modesense_control(struct se_device *dev, unsigned char *p)

static int spc_modesense_control(struct se_device *dev, u8 pc, u8 *p)

{

	p[0] = 0x0a;

	p[1] = 0x0a;



	/* No changeable values for now */

	if (pc == 1)

		goto out;



	p[2] = 2;

	/*

	 * From spc4r23, 7.4.7 Control mode page
@@ -729,20 +739,37 @@ static int spc_modesense_control(struct se_device *dev, unsigned char *p) 
	p[9] = 0xff;

	p[11] = 30;



out:

	return 12;

}



static int spc_modesense_caching(struct se_device *dev, unsigned char *p)

static int spc_modesense_caching(struct se_device *dev, u8 pc, u8 *p)

{

	p[0] = 0x08;

	p[1] = 0x12;



	/* No changeable values for now */

	if (pc == 1)

		goto out;



	if (dev->dev_attrib.emulate_write_cache > 0)

		p[2] = 0x04; /* Write Cache Enable */

	p[12] = 0x20; /* Disabled Read Ahead */



out:

	return 20;

}



static struct {

	uint8_t		page;

	uint8_t		subpage;

	int		(*emulate)(struct se_device *, u8, unsigned char *);

} modesense_handlers[] = {

	{ .page = 0x01, .subpage = 0x00, .emulate = spc_modesense_rwrecovery },

	{ .page = 0x08, .subpage = 0x00, .emulate = spc_modesense_caching },

	{ .page = 0x0a, .subpage = 0x00, .emulate = spc_modesense_control },

};



static void spc_modesense_write_protect(unsigned char *buf, int type)

{

	/*
@@ -769,77 +796,167 @@ static void spc_modesense_dpofua(unsigned char *buf, int type) 
	}

}



static int spc_modesense_blockdesc(unsigned char *buf, u64 blocks, u32 block_size)

{

	*buf++ = 8;

	put_unaligned_be32(min(blocks, 0xffffffffull), buf);

	buf += 4;

	put_unaligned_be32(block_size, buf);

	return 9;

}



static int spc_modesense_long_blockdesc(unsigned char *buf, u64 blocks, u32 block_size)

{

	if (blocks <= 0xffffffff)

		return spc_modesense_blockdesc(buf + 3, blocks, block_size) + 3;



	*buf++ = 1;		/* LONGLBA */

	buf += 2;

	*buf++ = 16;

	put_unaligned_be64(blocks, buf);

	buf += 12;

	put_unaligned_be32(block_size, buf);



	return 17;

}



static int spc_emulate_modesense(struct se_cmd *cmd)

{

	struct se_device *dev = cmd->se_dev;

	char *cdb = cmd->t_task_cdb;

	unsigned char *rbuf;

	unsigned char *buf, *map_buf;

	int type = dev->transport->get_device_type(dev);

	int ten = (cmd->t_task_cdb[0] == MODE_SENSE_10);

	u32 offset = ten ? 8 : 4;

	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;

	unsigned char buf[SE_MODE_PAGE_BUF];

	int ret;

	int i;



	memset(buf, 0, SE_MODE_PAGE_BUF);

	map_buf = transport_kmap_data_sg(cmd);



	switch (cdb[2] & 0x3f) {

	case 0x01:

		length = spc_modesense_rwrecovery(&buf[offset]);

		break;

	case 0x08:

		length = spc_modesense_caching(dev, &buf[offset]);

		break;

	case 0x0a:

		length = spc_modesense_control(dev, &buf[offset]);

		break;

	case 0x3f:

		length = spc_modesense_rwrecovery(&buf[offset]);

		length += spc_modesense_caching(dev, &buf[offset+length]);

		length += spc_modesense_control(dev, &buf[offset+length]);

		break;

	default:

		pr_err("MODE SENSE: unimplemented page/subpage: 0x%02x/0x%02x\n",

		       cdb[2] & 0x3f, cdb[3]);

		cmd->scsi_sense_reason = TCM_UNKNOWN_MODE_PAGE;

		return -EINVAL;

	/*

	 * If SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC is not set, then we

	 * know we actually allocated a full page.  Otherwise, if the

	 * data buffer is too small, allocate a temporary buffer so we

	 * don't have to worry about overruns in all our INQUIRY

	 * emulation handling.

	 */

	if (cmd->data_length < SE_MODE_PAGE_BUF &&

	    (cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC)) {

		buf = kzalloc(SE_MODE_PAGE_BUF, GFP_KERNEL);

		if (!buf) {

			transport_kunmap_data_sg(cmd);

			cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

			return -ENOMEM;

		}

	} else {

		buf = map_buf;

	}

	offset += length;



	if (ten) {

		offset -= 2;

		buf[0] = (offset >> 8) & 0xff;

		buf[1] = offset & 0xff;

		offset += 2;

	length = ten ? 2 : 1;



	/* DEVICE-SPECIFIC PARAMETER */

	if ((cmd->se_lun->lun_access & TRANSPORT_LUNFLAGS_READ_ONLY) ||

	    (cmd->se_deve &&

	     (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)))

			spc_modesense_write_protect(&buf[3], type);

		spc_modesense_write_protect(&buf[length], type);



	if ((dev->dev_attrib.emulate_write_cache > 0) &&

	    (dev->dev_attrib.emulate_fua_write > 0))

			spc_modesense_dpofua(&buf[3], type);

		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 {

		offset -= 1;

		buf[0] = offset & 0xff;

		offset += 1;

				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 ((cmd->se_lun->lun_access & TRANSPORT_LUNFLAGS_READ_ONLY) ||

		    (cmd->se_deve &&

		    (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)))

			spc_modesense_write_protect(&buf[2], type);

	if (page == 0x3f) {

		if (subpage != 0x00 && subpage != 0xff) {

			cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;

			length = -EINVAL;

			goto out;

		}



		if ((dev->dev_attrib.emulate_write_cache > 0) &&

		    (dev->dev_attrib.emulate_fua_write > 0))

			spc_modesense_dpofua(&buf[2], type);

		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(dev, pc, &buf[length]);

				if (!ten && length + ret >= 255)

					break;

				length += ret;

			}

		}



	rbuf = transport_kmap_data_sg(cmd);

	if (rbuf) {

		memcpy(rbuf, buf, min(offset, cmd->data_length));

		transport_kunmap_data_sg(cmd);

		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(dev, 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);



	cmd->scsi_sense_reason = TCM_UNKNOWN_MODE_PAGE;

	return -EINVAL;



set_length:

	if (ten)

		put_unaligned_be16(length - 2, buf);

	else

		buf[0] = length - 1;



out:

	if (buf != map_buf) {

		memcpy(map_buf, buf, cmd->data_length);

		kfree(buf);

	}



	transport_kunmap_data_sg(cmd);

	target_complete_cmd(cmd, GOOD);

	return 0;

}

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