nvme: add support for DIOCGIDENT

Add support for the DIOCGIDENT ioctl to both nvme controller device
nodes and namespace device nodes.

This information was already available via the nda(4) device node.
However, mapping /dev/nvmeX to /dev/ndaY device nodes is not
straightforward, so it's better to get it directly from the /dev/nvme
device node.

PR:		290259
MFC after:	2 weeks
Sponsored by:	ConnectWise
Submitted by:	imp (mostly)
Pull Request:	https://github.com/freebsd/freebsd-src/pull/1875

sys/dev/nvme/nvme_ctrlr.c

@@ -33,6 +33,7 @@
 #include <sys/buf.h>
 #include <sys/bus.h>
 #include <sys/conf.h>
+#include <sys/disk.h>
 #include <sys/ioccom.h>
 #include <sys/proc.h>
 #include <sys/smp.h>
@@ -1253,6 +1254,24 @@ nvme_ctrlr_poll(struct nvme_controller *ctrlr)
 			nvme_qpair_process_completions(&ctrlr->ioq[i]);
 }
 
+/*
+ * Copy the NVME device's serial number to the provided buffer, which must be
+ * at least DISK_IDENT_SIZE bytes large.
+ */
+void
+nvme_ctrlr_get_ident(const struct nvme_controller *ctrlr, uint8_t *sn)
+{
+	_Static_assert(NVME_SERIAL_NUMBER_LENGTH < DISK_IDENT_SIZE,
+		"NVME serial number too big for disk ident");
+
+	memmove(sn, ctrlr->cdata.sn, NVME_SERIAL_NUMBER_LENGTH);
+	sn[NVME_SERIAL_NUMBER_LENGTH] = '\0';
+	for (int i = 0; sn[i] != '\0'; i++) {
+		if (sn[i] < 0x20 || sn[i] >= 0x80)
+			sn[i] = ' ';
+	}
+}
+
 /*
  * Poll the single-vector interrupt case: num_io_queues will be 1 and
  * there's only a single vector. While we're polling, we mask further
@@ -1495,6 +1514,11 @@ nvme_ctrlr_ioctl(struct cdev *cdev, u_long cmd, caddr_t arg, int flag,
 	case NVME_GET_CONTROLLER_DATA:
 		memcpy(arg, &ctrlr->cdata, sizeof(ctrlr->cdata));
 		break;
+	case DIOCGIDENT: {
+		uint8_t *sn = arg;
+		nvme_ctrlr_get_ident(ctrlr, sn);
+		break;
+	}
 	/* Linux Compatible (see nvme_linux.h) */
 	case NVME_IOCTL_ID:
 		td->td_retval[0] = 0xfffffffful;

sys/dev/nvme/nvme_ns.c

@@ -88,6 +88,11 @@ nvme_ns_ioctl(struct cdev *cdev, u_long cmd, caddr_t arg, int flag,
 		gnsid->nsid = ns->id;
 		break;
 	}
+	case DIOCGIDENT: {
+		uint8_t *sn = arg;
+		nvme_ctrlr_get_ident(ctrlr, sn);
+		break;
+	}
 	case DIOCGMEDIASIZE:
 		*(off_t *)arg = (off_t)nvme_ns_get_size(ns);
 		break;

sys/dev/nvme/nvme_private.h

@@ -563,6 +563,7 @@ void	nvme_notify_new_controller(struct nvme_controller *ctrlr);
 void	nvme_notify_ns(struct nvme_controller *ctrlr, int nsid);
 
 void	nvme_ctrlr_shared_handler(void *arg);
+void	nvme_ctrlr_get_ident(const struct nvme_controller *ctrlr, uint8_t *sn);
 void	nvme_ctrlr_poll(struct nvme_controller *ctrlr);
 
 int	nvme_ctrlr_suspend(struct nvme_controller *ctrlr);