Add the method to query for a uniqueue ID of a given type by looking
it up in the cached device identification VPD page.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
drivers/scsi/sd.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d8f6add416c0a..ea1489d3e8497 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1757,6 +1757,42 @@ static void sd_rescan(struct device *dev)
sd_revalidate_disk(sdkp->disk);
}
+static int sd_get_unique_id(struct gendisk *disk, u8 id[16], u8 type)
+{
+ struct scsi_device *sdev = scsi_disk(disk)->device;
+ const struct scsi_vpd *vpd;
+ const unsigned char *d;
+ int len = -ENXIO;
+
+ rcu_read_lock();
+ vpd = rcu_dereference(sdev->vpd_pg83);
+ if (!vpd)
+ goto out_unlock;
+
+ len = -EINVAL;
+ for (d = vpd->data + 4; d < vpd->data + vpd->len; d += d[3] + 4) {
+ /* we only care about designators with LU association */
+ if (((d[1] >> 4) & 0x3) != 0x00)
+ continue;
+ if ((d[1] & 0xf) != type)
+ continue;
+
+ /*
+ * Only exit early if a 16-byte descriptor was found. Otherwise
+ * keep looking as one with more entropy might still show up.
+ */
+ len = d[3];
+ if (len != 8 && len != 12 && len != 16)
+ continue;
+ memcpy(id, d + 4, len);
+ if (len == 16)
+ break;
+ }
+out_unlock:
+ rcu_read_unlock();
+ return len;
+}
+
static char sd_pr_type(enum pr_type type)
{
switch (type) {
@@ -1861,6 +1897,7 @@ static const struct block_device_operations sd_fops = {
.check_events = sd_check_events,
.unlock_native_capacity = sd_unlock_native_capacity,
.report_zones = sd_zbc_report_zones,
+ .get_unique_id = sd_get_unique_id,
.pr_ops = &sd_pr_ops,
};
--
2.30.2
