Commit 9983bed3 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Martin K. Petersen
Browse files

scsi: Add scsi_vpd_lun_id() 



Add a function scsi_vpd_lun_id() to return a unique device
identifcation based on the designation descriptors of
VPD page 0x83.

As devices might implement several descriptors the order
of preference is:
- NAA IEE Registered Extended
- EUI-64 based 16-byte
- EUI-64 based 12-byte
- NAA IEEE Registered
- NAA IEEE Extended
A SCSI name string descriptor is preferred to all of them
if the identification is longer than 16 bytes.

The returned unique device identification will be formatted
as a SCSI Name string to avoid clashes between different
designator types.

[mkp: Fixed up kernel doc comment from Johannes]

Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarEwan Milne <emilne@redhat.com>
Reviewed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent e2d817db

drivers/scsi/scsi_lib.c

+140 −0
Original line number Diff line number Diff line
@@ -3154,3 +3154,143 @@ void sdev_enable_disk_events(struct scsi_device *sdev) 
	atomic_dec(&sdev->disk_events_disable_depth);

}

EXPORT_SYMBOL(sdev_enable_disk_events);



/**

 * scsi_vpd_lun_id - return a unique device identification

 * @sdev: SCSI device

 * @id:   buffer for the identification

 * @id_len:  length of the buffer

 *

 * Copies a unique device identification into @id based

 * on the information in the VPD page 0x83 of the device.

 * The string will be formatted as a SCSI name string.

 *

 * Returns the length of the identification or error on failure.

 * If the identifier is longer than the supplied buffer the actual

 * identifier length is returned and the buffer is not zero-padded.

 */

int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)

{

	u8 cur_id_type = 0xff;

	u8 cur_id_size = 0;

	unsigned char *d, *cur_id_str;

	unsigned char __rcu *vpd_pg83;

	int id_size = -EINVAL;



	rcu_read_lock();

	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);

	if (!vpd_pg83) {

		rcu_read_unlock();

		return -ENXIO;

	}



	/*

	 * Look for the correct descriptor.

	 * Order of preference for lun descriptor:

	 * - SCSI name string

	 * - NAA IEEE Registered Extended

	 * - EUI-64 based 16-byte

	 * - EUI-64 based 12-byte

	 * - NAA IEEE Registered

	 * - NAA IEEE Extended

	 * as longer descriptors reduce the likelyhood

	 * of identification clashes.

	 */



	/* The id string must be at least 20 bytes + terminating NULL byte */

	if (id_len < 21) {

		rcu_read_unlock();

		return -EINVAL;

	}



	memset(id, 0, id_len);

	d = vpd_pg83 + 4;

	while (d < vpd_pg83 + sdev->vpd_pg83_len) {

		/* Skip designators not referring to the LUN */

		if ((d[1] & 0x30) != 0x00)

			goto next_desig;



		switch (d[1] & 0xf) {

		case 0x2:

			/* EUI-64 */

			if (cur_id_size > d[3])

				break;

			/* Prefer NAA IEEE Registered Extended */

			if (cur_id_type == 0x3 &&

			    cur_id_size == d[3])

				break;

			cur_id_size = d[3];

			cur_id_str = d + 4;

			cur_id_type = d[1] & 0xf;

			switch (cur_id_size) {

			case 8:

				id_size = snprintf(id, id_len,

						   "eui.%8phN",

						   cur_id_str);

				break;

			case 12:

				id_size = snprintf(id, id_len,

						   "eui.%12phN",

						   cur_id_str);

				break;

			case 16:

				id_size = snprintf(id, id_len,

						   "eui.%16phN",

						   cur_id_str);

				break;

			default:

				cur_id_size = 0;

				break;

			}

			break;

		case 0x3:

			/* NAA */

			if (cur_id_size > d[3])

				break;

			cur_id_size = d[3];

			cur_id_str = d + 4;

			cur_id_type = d[1] & 0xf;

			switch (cur_id_size) {

			case 8:

				id_size = snprintf(id, id_len,

						   "naa.%8phN",

						   cur_id_str);

				break;

			case 16:

				id_size = snprintf(id, id_len,

						   "naa.%16phN",

						   cur_id_str);

				break;

			default:

				cur_id_size = 0;

				break;

			}

			break;

		case 0x8:

			/* SCSI name string */

			if (cur_id_size + 4 > d[3])

				break;

			/* Prefer others for truncated descriptor */

			if (cur_id_size && d[3] > id_len)

				break;

			cur_id_size = id_size = d[3];

			cur_id_str = d + 4;

			cur_id_type = d[1] & 0xf;

			if (cur_id_size >= id_len)

				cur_id_size = id_len - 1;

			memcpy(id, cur_id_str, cur_id_size);

			/* Decrease priority for truncated descriptor */

			if (cur_id_size != id_size)

				cur_id_size = 6;

			break;

		default:

			break;

		}

next_desig:

		d += d[3] + 4;

	}

	rcu_read_unlock();



	return id_size;

}

EXPORT_SYMBOL(scsi_vpd_lun_id);

include/scsi/scsi_device.h

+1 −0
Original line number Diff line number Diff line
@@ -415,6 +415,7 @@ static inline int scsi_execute_req(struct scsi_device *sdev, 
}

extern void sdev_disable_disk_events(struct scsi_device *sdev);

extern void sdev_enable_disk_events(struct scsi_device *sdev);

extern int scsi_vpd_lun_id(struct scsi_device *, char *, size_t);



#ifdef CONFIG_PM

extern int scsi_autopm_get_device(struct scsi_device *);

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