Patch "sd: implement ->get_unique_id" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    sd: implement ->get_unique_id

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     sd-implement-get_unique_id.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 654d187b5537fcf9d683bdc8df51817cc5105a20
Author: Christoph Hellwig <hch@xxxxxx>
Date:   Thu Oct 21 08:06:02 2021 +0200

    sd: implement ->get_unique_id
    
    [ Upstream commit b83ce214af3885437ff223b3a0c8ec6072a84167 ]
    
    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>
    Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
    Link: https://lore.kernel.org/r/20211021060607.264371-3-hch@xxxxxx
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 1e887c11e83d0..79992d1c7864c 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1758,6 +1758,44 @@ 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) {
@@ -1862,6 +1900,7 @@ 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,
 };