diff mbox series

[2/7] sd: implement ->get_unique_id

Message ID 20211021060607.264371-3-hch@lst.de (mailing list archive)
State Not Applicable
Headers show
Series [1/7] block: add a ->get_unique_id method | expand

Commit Message

Christoph Hellwig Oct. 21, 2021, 6:06 a.m. UTC 
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@lst.de>
---
 drivers/scsi/sd.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

Comments

Hannes Reinecke Oct. 21, 2021, 1:34 p.m. UTC | #1 
On 10/21/21 8:06 AM, Christoph Hellwig wrote:
> 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@lst.de>
> ---
>   drivers/scsi/sd.c | 39 +++++++++++++++++++++++++++++++++++++++
>   1 file changed, 39 insertions(+)
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
diff mbox series

Patch

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d8f6add416c0a..9b386ca39a913 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1757,6 +1757,44 @@  static void sd_rescan(struct device *dev)
 	sd_revalidate_disk(sdkp->disk);
 }
 
+static int sd_get_unique_id(struct gendisk *disk, u8 id[16],
+		enum blk_unique_id type)
+{
+	struct scsi_device *sdev = scsi_disk(disk)->device;
+	const struct scsi_vpd *vpd;
+	const unsigned char *d;
+	int ret = -ENXIO, len;
+
+	rcu_read_lock();
+	vpd = rcu_dereference(sdev->vpd_pg83);
+	if (!vpd)
+		goto out_unlock;
+
+	ret = -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;
+		ret = len;
+		memcpy(id, d + 4, len);
+		if (len == 16)
+			break;
+	}
+out_unlock:
+	rcu_read_unlock();
+	return ret;
+}
+
 static char sd_pr_type(enum pr_type type)
 {
 	switch (type) {
@@ -1861,6 +1899,7 @@  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,
 };