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.
Reviewed-by: Ewan Milne <emilne@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
---
drivers/scsi/scsi_lib.c | 140 +++++++++++++++++++++++++++++++++++++++++++++
include/scsi/scsi_device.h | 1 +
2 files changed, 141 insertions(+)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index cbfc599..3cb295c 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -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);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index bde4077..4c49cfa 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -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 *);
--
1.8.5.6
--
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