Index: sys/cam/cam_ccb.h
===================================================================
--- sys/cam/cam_ccb.h
+++ sys/cam/cam_ccb.h
@@ -1268,6 +1268,7 @@
 #define	CDAI_TYPE_EXT_INQ	5
 #define	CDAI_TYPE_NVME_CNTRL	6	/* NVMe Identify Controller data */
 #define	CDAI_TYPE_NVME_NS	7	/* NVMe Identify Namespace data */
+#define	CDAI_TYPE_MODE_DEV_SPEC	8	/* Device specific byte of mode header */
 	off_t bufsiz;			/* IN: Size of external buffer */
 #define	CAM_SCSI_DEVID_MAXLEN	65536	/* length in buffer is an uint16_t */
 	off_t provsiz;			/* OUT: Size required/used */
Index: sys/cam/cam_xpt_internal.h
===================================================================
--- sys/cam/cam_xpt_internal.h
+++ sys/cam/cam_xpt_internal.h
@@ -133,6 +133,7 @@
 					 * queuing for a device.
 					 */
 	u_int8_t	 queue_flags;	/* Queue flags from the control page */
+	u_int8_t	 dev_spec;	/* Device specific byte of mode header */
 	u_int8_t	 serial_num_len;
 	u_int8_t	*serial_num;
 	u_int32_t	 flags;
Index: sys/cam/scsi/scsi_da.c
===================================================================
--- sys/cam/scsi/scsi_da.c
+++ sys/cam/scsi/scsi_da.c
@@ -5596,6 +5596,34 @@
 	softc->disk->d_devstat->block_size = softc->params.secsize;
 	softc->disk->d_devstat->flags &= ~DEVSTAT_BS_UNAVAILABLE;
 
+	/* Refresh the write protect status as well. */
+	{
+		struct ccb_dev_advinfo cdai;
+		uint8_t dev_spec;
+
+		xpt_setup_ccb(&cdai.ccb_h, periph->path, CAM_PRIORITY_NORMAL);
+		cdai.ccb_h.func_code = XPT_DEV_ADVINFO;
+		cdai.buftype = CDAI_TYPE_MODE_DEV_SPEC;
+		cdai.flags = 0;
+		cdai.bufsiz = 1;
+		cdai.buf = &dev_spec;
+		xpt_action((union ccb *)&cdai);
+		if ((cdai.ccb_h.status & CAM_DEV_QFRZN) != 0)
+			cam_release_devq(cdai.ccb_h.path, 0, 0, 0, FALSE);
+		if (cdai.ccb_h.status != CAM_REQ_CMP) {
+			xpt_print(periph->path, "%s: failed to get dev_spec\n",
+				  __func__);
+			/* Use cam_error_print() to decode the status */
+			cam_error_print((union ccb *)&cdai, CAM_ESF_CAM_STATUS,
+					CAM_EPF_ALL);
+		} else {
+			if ((dev_spec & 0x80) != 0)
+				softc->disk->d_flags |= DISKFLAG_WRITE_PROTECT;
+			else
+				softc->disk->d_flags &= ~DISKFLAG_WRITE_PROTECT;
+		}
+	}
+
 	error = disk_resize(softc->disk, M_NOWAIT);
 	if (error != 0)
 		xpt_print(periph->path, "disk_resize(9) failed, error = %d\n", error);
Index: sys/cam/scsi/scsi_xpt.c
===================================================================
--- sys/cam/scsi/scsi_xpt.c
+++ sys/cam/scsi/scsi_xpt.c
@@ -1423,6 +1423,7 @@
 			    + mode_hdr->blk_desc_len;
 			page = (struct scsi_control_page *)offset;
 			path->device->queue_flags = page->queue_flags;
+			path->device->dev_spec = mode_hdr->dev_spec;
 		} else if (cam_periph_error(done_ccb, 0,
 					    SF_RETRY_UA|SF_NO_PRINT,
 					    &softc->saved_ccb) == ERESTART) {
@@ -2615,6 +2616,18 @@
 			amt = cdai->bufsiz;
 		memcpy(cdai->buf, device->ext_inq, amt);
 		break;
+	case CDAI_TYPE_MODE_DEV_SPEC:
+		/*
+		 * We fetch mode parameter header during probe.
+		 * We don't allow changing it.
+		 */
+		if (cdai->flags & CDAI_FLAG_STORE)
+			return;
+		cdai->provsiz = 1;
+		if (cdai->bufsiz == 0)
+			break;
+		cdai->buf[0] = device->dev_spec;
+		break;
 	default:
 		return;
 	}
Index: sys/geom/geom_disk.h
===================================================================
--- sys/geom/geom_disk.h
+++ sys/geom/geom_disk.h
@@ -124,13 +124,14 @@
 	LIST_HEAD(,disk_alias)	d_aliases;
 };
 
-#define DISKFLAG_RESERVED	0x1	/* Was NEEDSGIANT */
-#define DISKFLAG_OPEN		0x2
-#define DISKFLAG_CANDELETE	0x4
-#define DISKFLAG_CANFLUSHCACHE	0x8
-#define	DISKFLAG_UNMAPPED_BIO	0x10
-#define	DISKFLAG_DIRECT_COMPLETION	0x20
-#define	DISKFLAG_CANZONE	0x80
+#define	DISKFLAG_RESERVED		0x0001	/* Was NEEDSGIANT */
+#define	DISKFLAG_OPEN			0x0002
+#define	DISKFLAG_CANDELETE		0x0004
+#define	DISKFLAG_CANFLUSHCACHE		0x0008
+#define	DISKFLAG_UNMAPPED_BIO		0x0010
+#define	DISKFLAG_DIRECT_COMPLETION	0x0020
+#define	DISKFLAG_CANZONE		0x0080
+#define	DISKFLAG_WRITE_PROTECT		0x0100
 
 struct disk *disk_alloc(void);
 void disk_create(struct disk *disk, int version);
Index: sys/geom/geom_disk.c
===================================================================
--- sys/geom/geom_disk.c
+++ sys/geom/geom_disk.c
@@ -120,14 +120,18 @@
 	e += pp->ace;
 	error = 0;
 	if ((pp->acr + pp->acw + pp->ace) == 0 && (r + w + e) > 0) {
-		if (dp->d_open != NULL) {
+		/*
+		 * It would be better to defer this decision to d_open if
+		 * it was able to take flags.
+		 */
+		if (w > 0 && (dp->d_flags & DISKFLAG_WRITE_PROTECT) != 0)
+			error = ENODEV;
+		if (error == 0 && dp->d_open != NULL)
 			error = dp->d_open(dp);
-			if (bootverbose && error != 0)
-				printf("Opened disk %s -> %d\n",
-				    pp->name, error);
-			if (error != 0)
-				return (error);
-		}
+		if (bootverbose && error != 0)
+			printf("Opened disk %s -> %d\n", pp->name, error);
+		if (error != 0)
+			return (error);
 		pp->sectorsize = dp->d_sectorsize;
 		if (dp->d_maxsize == 0) {
 			printf("WARNING: Disk drive %s%d has no d_maxsize\n",
@@ -1041,7 +1045,8 @@
 		"\4CANFLUSHCACHE"
 		"\5UNMAPPEDBIO"
 		"\6DIRECTCOMPLETION"
-		"\10CANZONE");
+		"\10CANZONE"
+		"\11WRITEPROTECT");
 
 	sbuf_finish(sb);
 	error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);