From 9309a460b23a8cda8d47c5f775da7fc6472d9925 Mon Sep 17 00:00:00 2001
From: Alan Somers <asomers@FreeBSD.org>
Date: Fri, 7 Apr 2023 10:07:50 -0600
Subject: [PATCH] Implement GEOM::rotation_rate for gmirror

If all of the mirror's children have the same rotation rate, report
that.  But if they have mixed rotation rates, or if any child has an
unknown rotation rate, report "Unknown".

MFC after:	2 weeks
Sponsored by:	Axcient
Reviewed by:	imp
Differential Revision: https://reviews.freebsd.org/D39458
---
 sys/geom/mirror/g_mirror.c | 29 +++++++++++++++++++++++++++++
 sys/geom/mirror/g_mirror.h |  1 +
 2 files changed, 30 insertions(+)

diff --git a/sys/geom/mirror/g_mirror.c b/sys/geom/mirror/g_mirror.c
index 94e615c8038d..9153345cc7e2 100644
--- a/sys/geom/mirror/g_mirror.c
+++ b/sys/geom/mirror/g_mirror.c
@@ -48,6 +48,7 @@ __FBSDID("$FreeBSD$");
 
 #include <geom/geom.h>
 #include <geom/geom_dbg.h>
+#include <geom/geom_disk.h>
 #include <geom/mirror/g_mirror.h>
 
 FEATURE(geom_mirror, "GEOM mirroring support");
@@ -479,6 +480,10 @@ g_mirror_init_disk(struct g_mirror_softc *sc, struct g_provider *pp,
 	error = g_getattr("GEOM::candelete", disk->d_consumer, &i);
 	if (error == 0 && i != 0)
 		disk->d_flags |= G_MIRROR_DISK_FLAG_CANDELETE;
+	error = g_getattr("GEOM::rotation_rate", disk->d_consumer,
+		&disk->d_rotation_rate);
+	if (error)
+		disk->d_rotation_rate = DISK_RR_UNKNOWN;
 	if (md->md_provider[0] != '\0')
 		disk->d_flags |= G_MIRROR_DISK_FLAG_HARDCODED;
 	disk->d_sync.ds_consumer = NULL;
@@ -1147,6 +1152,27 @@ g_mirror_kernel_dump(struct bio *bp)
 	    g_mirror_get_diskname(disk));
 }
 
+static void
+g_mirror_rotation_rate(struct bio *bp)
+{
+	struct g_mirror_softc *sc;
+	struct g_mirror_disk *disk;
+	bool first = true;
+	uint16_t rr = DISK_RR_UNKNOWN;
+
+	sc = bp->bio_to->private;
+	LIST_FOREACH(disk, &sc->sc_disks, d_next) {
+		if (first)
+			rr = disk->d_rotation_rate;
+		else if (rr != disk->d_rotation_rate) {
+			rr = DISK_RR_UNKNOWN;
+			break;
+		}
+		first = false;
+	}
+	g_handleattr(bp, "GEOM::rotation_rate", &rr, sizeof(rr));
+}
+
 static void
 g_mirror_start(struct bio *bp)
 {
@@ -1176,6 +1202,9 @@ g_mirror_start(struct bio *bp)
 		} else if (strcmp("GEOM::kerneldump", bp->bio_attribute) == 0) {
 			g_mirror_kernel_dump(bp);
 			return;
+		} else if (!strcmp(bp->bio_attribute, "GEOM::rotation_rate")) {
+			g_mirror_rotation_rate(bp);
+			return;
 		}
 		/* FALLTHROUGH */
 	default:
diff --git a/sys/geom/mirror/g_mirror.h b/sys/geom/mirror/g_mirror.h
index 7cec94adae18..09436ec164e6 100644
--- a/sys/geom/mirror/g_mirror.h
+++ b/sys/geom/mirror/g_mirror.h
@@ -139,6 +139,7 @@ struct g_mirror_disk {
 	u_int		 d_init_ndisks;	/* Initial number of mirror components */
 	uint32_t	 d_init_slice;	/* Initial slice size */
 	uint8_t		 d_init_balance;/* Initial balance */
+	uint16_t	 d_rotation_rate;/* Disk's rotation rate */
 	uint64_t	 d_init_mediasize;/* Initial mediasize */
 };
 #define	d_name	d_consumer->provider->name