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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: Hannes Reinecke <hare@suse.de> Reviewed-by: Ewan Milne <emilne@redhat.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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@ -3154,3 +3154,143 @@ void sdev_enable_disk_events(struct scsi_device *sdev)
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atomic_dec(&sdev->disk_events_disable_depth);
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}
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EXPORT_SYMBOL(sdev_enable_disk_events);
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/**
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* scsi_vpd_lun_id - return a unique device identification
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* @sdev: SCSI device
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* @id: buffer for the identification
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* @id_len: length of the buffer
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*
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* Copies a unique device identification into @id based
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* on the information in the VPD page 0x83 of the device.
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* The string will be formatted as a SCSI name string.
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*
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* Returns the length of the identification or error on failure.
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* If the identifier is longer than the supplied buffer the actual
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* identifier length is returned and the buffer is not zero-padded.
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*/
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int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
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{
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u8 cur_id_type = 0xff;
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u8 cur_id_size = 0;
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unsigned char *d, *cur_id_str;
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unsigned char __rcu *vpd_pg83;
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int id_size = -EINVAL;
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rcu_read_lock();
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vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
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if (!vpd_pg83) {
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rcu_read_unlock();
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return -ENXIO;
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}
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/*
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* Look for the correct descriptor.
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* Order of preference for lun descriptor:
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* - SCSI name string
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* - NAA IEEE Registered Extended
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* - EUI-64 based 16-byte
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* - EUI-64 based 12-byte
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* - NAA IEEE Registered
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* - NAA IEEE Extended
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* as longer descriptors reduce the likelyhood
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* of identification clashes.
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*/
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/* The id string must be at least 20 bytes + terminating NULL byte */
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if (id_len < 21) {
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rcu_read_unlock();
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return -EINVAL;
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}
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memset(id, 0, id_len);
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d = vpd_pg83 + 4;
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while (d < vpd_pg83 + sdev->vpd_pg83_len) {
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/* Skip designators not referring to the LUN */
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if ((d[1] & 0x30) != 0x00)
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goto next_desig;
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switch (d[1] & 0xf) {
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case 0x2:
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/* EUI-64 */
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if (cur_id_size > d[3])
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break;
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/* Prefer NAA IEEE Registered Extended */
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if (cur_id_type == 0x3 &&
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cur_id_size == d[3])
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break;
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cur_id_size = d[3];
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cur_id_str = d + 4;
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cur_id_type = d[1] & 0xf;
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switch (cur_id_size) {
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case 8:
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id_size = snprintf(id, id_len,
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"eui.%8phN",
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cur_id_str);
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break;
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case 12:
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id_size = snprintf(id, id_len,
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"eui.%12phN",
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cur_id_str);
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break;
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case 16:
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id_size = snprintf(id, id_len,
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"eui.%16phN",
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cur_id_str);
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break;
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default:
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cur_id_size = 0;
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break;
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}
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break;
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case 0x3:
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/* NAA */
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if (cur_id_size > d[3])
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break;
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cur_id_size = d[3];
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cur_id_str = d + 4;
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cur_id_type = d[1] & 0xf;
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switch (cur_id_size) {
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case 8:
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id_size = snprintf(id, id_len,
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"naa.%8phN",
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cur_id_str);
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break;
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case 16:
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id_size = snprintf(id, id_len,
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"naa.%16phN",
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cur_id_str);
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break;
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default:
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cur_id_size = 0;
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break;
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}
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break;
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case 0x8:
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/* SCSI name string */
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if (cur_id_size + 4 > d[3])
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break;
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/* Prefer others for truncated descriptor */
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if (cur_id_size && d[3] > id_len)
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break;
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cur_id_size = id_size = d[3];
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cur_id_str = d + 4;
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cur_id_type = d[1] & 0xf;
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if (cur_id_size >= id_len)
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cur_id_size = id_len - 1;
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memcpy(id, cur_id_str, cur_id_size);
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/* Decrease priority for truncated descriptor */
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if (cur_id_size != id_size)
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cur_id_size = 6;
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break;
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default:
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break;
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}
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next_desig:
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d += d[3] + 4;
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}
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rcu_read_unlock();
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return id_size;
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}
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EXPORT_SYMBOL(scsi_vpd_lun_id);
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@ -415,6 +415,7 @@ static inline int scsi_execute_req(struct scsi_device *sdev,
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}
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extern void sdev_disable_disk_events(struct scsi_device *sdev);
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extern void sdev_enable_disk_events(struct scsi_device *sdev);
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extern int scsi_vpd_lun_id(struct scsi_device *, char *, size_t);
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#ifdef CONFIG_PM
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extern int scsi_autopm_get_device(struct scsi_device *);
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