scsi: core: Query the Block Limits Extension VPD page

Parse the Reduced Stream Control Supported (RSCS) bit from the block limits
extension VPD page. The RSCS bit is defined in SBC-5 r05
(https://www.t10.org/cgi-bin/ac.pl?t=f&f=sbc5r05.pdf).

Reviewed-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Daejun Park <daejun7.park@samsung.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240130214911.1863909-10-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: bvanassche

drivers/scsi/scsi.c

@@ -499,6 +499,8 @@ void scsi_attach_vpd(struct scsi_device *sdev)
 			scsi_update_vpd_page(sdev, 0xb1, &sdev->vpd_pgb1);
 		if (vpd_buf->data[i] == 0xb2)
 			scsi_update_vpd_page(sdev, 0xb2, &sdev->vpd_pgb2);
+		if (vpd_buf->data[i] == 0xb7)
+			scsi_update_vpd_page(sdev, 0xb7, &sdev->vpd_pgb7);
 	}
 	kfree(vpd_buf);
 }

drivers/scsi/scsi_sysfs.c

@@ -449,6 +449,7 @@ static void scsi_device_dev_release(struct device *dev)
 	struct scsi_vpd *vpd_pg80 = NULL, *vpd_pg83 = NULL;
 	struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL;
 	struct scsi_vpd *vpd_pgb0 = NULL, *vpd_pgb1 = NULL, *vpd_pgb2 = NULL;
+	struct scsi_vpd *vpd_pgb7 = NULL;
 	unsigned long flags;
 
 	might_sleep();
@@ -494,6 +495,8 @@ static void scsi_device_dev_release(struct device *dev)
 				       lockdep_is_held(&sdev->inquiry_mutex));
 	vpd_pgb2 = rcu_replace_pointer(sdev->vpd_pgb2, vpd_pgb2,
 				       lockdep_is_held(&sdev->inquiry_mutex));
+	vpd_pgb7 = rcu_replace_pointer(sdev->vpd_pgb7, vpd_pgb7,
+				       lockdep_is_held(&sdev->inquiry_mutex));
 	mutex_unlock(&sdev->inquiry_mutex);
 
 	if (vpd_pg0)
@@ -510,6 +513,8 @@ static void scsi_device_dev_release(struct device *dev)
 		kfree_rcu(vpd_pgb1, rcu);
 	if (vpd_pgb2)
 		kfree_rcu(vpd_pgb2, rcu);
+	if (vpd_pgb7)
+		kfree_rcu(vpd_pgb7, rcu);
 	kfree(sdev->inquiry);
 	kfree(sdev);
 
@@ -921,6 +926,7 @@ sdev_vpd_pg_attr(pg89);
 sdev_vpd_pg_attr(pgb0);
 sdev_vpd_pg_attr(pgb1);
 sdev_vpd_pg_attr(pgb2);
+sdev_vpd_pg_attr(pgb7);
 sdev_vpd_pg_attr(pg0);
 
 static ssize_t show_inquiry(struct file *filep, struct kobject *kobj,
@@ -1295,6 +1301,9 @@ static umode_t scsi_sdev_bin_attr_is_visible(struct kobject *kobj,
 	if (attr == &dev_attr_vpd_pgb2 && !sdev->vpd_pgb2)
 		return 0;
 
+	if (attr == &dev_attr_vpd_pgb7 && !sdev->vpd_pgb7)
+		return 0;
+
 	return S_IRUGO;
 }
 
@@ -1347,6 +1356,7 @@ static struct bin_attribute *scsi_sdev_bin_attrs[] = {
 	&dev_attr_vpd_pgb0,
 	&dev_attr_vpd_pgb1,
 	&dev_attr_vpd_pgb2,
+	&dev_attr_vpd_pgb7,
 	&dev_attr_inquiry,
 	NULL
 };

drivers/scsi/sd.c

@@ -3108,6 +3108,18 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
 	rcu_read_unlock();
 }
 
+/* Parse the Block Limits Extension VPD page (0xb7) */
+static void sd_read_block_limits_ext(struct scsi_disk *sdkp)
+{
+	struct scsi_vpd *vpd;
+
+	rcu_read_lock();
+	vpd = rcu_dereference(sdkp->device->vpd_pgb7);
+	if (vpd && vpd->len >= 2)
+		sdkp->rscs = vpd->data[5] & 1;
+	rcu_read_unlock();
+}
+
 /**
  * sd_read_block_characteristics - Query block dev. characteristics
  * @sdkp: disk to query
@@ -3459,6 +3471,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 		if (scsi_device_supports_vpd(sdp)) {
 			sd_read_block_provisioning(sdkp);
 			sd_read_block_limits(sdkp);
+			sd_read_block_limits_ext(sdkp);
 			sd_read_block_characteristics(sdkp);
 			sd_zbc_read_zones(sdkp, buffer);
 			sd_read_cpr(sdkp);

drivers/scsi/sd.h

@@ -151,6 +151,7 @@ struct scsi_disk {
 	unsigned	urswrz : 1;
 	unsigned	security : 1;
 	unsigned	ignore_medium_access_errors : 1;
+	bool		rscs : 1; /* reduced stream control support */
 };
 #define to_scsi_disk(obj) container_of(obj, struct scsi_disk, disk_dev)
 

include/scsi/scsi_device.h

@@ -153,6 +153,7 @@ struct scsi_device {
 	struct scsi_vpd __rcu *vpd_pgb0;
 	struct scsi_vpd __rcu *vpd_pgb1;
 	struct scsi_vpd __rcu *vpd_pgb2;
+	struct scsi_vpd __rcu *vpd_pgb7;
 
 	struct scsi_target      *sdev_target;