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sd: implement ->get_unique_id

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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>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20211021060607.264371-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-10-21 08:06:02 +02:00 committed by Jens Axboe
parent 9208d41497
commit b83ce214af
1 changed files with 39 additions and 0 deletions
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39
drivers/scsi/sd.c
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@ -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,
};