From 25c9cca75768bbbd1f970d5b5da5d3773e20b080 Mon Sep 17 00:00:00 2001
From: Mark Johnston <markj@FreeBSD.org>
Date: Tue, 30 Oct 2018 00:22:14 +0000
Subject: [PATCH] Have gconcat advertise delete support if one of its disks
 does.

This follows the example set by other multi-disk GEOM classes.

PR:		232676
Tested by:	noah.bergbauer@tum.de
MFC after:	1 month
---
 sys/geom/concat/g_concat.c | 35 +++++++++++++++++++++++++++++++++++
 sys/geom/concat/g_concat.h |  1 +
 2 files changed, 36 insertions(+)

diff --git a/sys/geom/concat/g_concat.c b/sys/geom/concat/g_concat.c
index 8e1a5dd60698..f9be59101592 100644
--- a/sys/geom/concat/g_concat.c
+++ b/sys/geom/concat/g_concat.c
@@ -205,6 +205,27 @@ g_concat_access(struct g_provider *pp, int dr, int dw, int de)
 	return (error);
 }
 
+static void
+g_concat_candelete(struct bio *bp)
+{
+	struct g_concat_softc *sc;
+	struct g_concat_disk *disk;
+	int i, *val;
+
+	val = (int *)bp->bio_data;
+	*val = 0;
+
+	sc = bp->bio_to->geom->softc;
+	for (i = 0; i < sc->sc_ndisks; i++) {
+		disk = &sc->sc_disks[i];
+		if (!disk->d_removed && disk->d_candelete) {
+			*val = 1;
+			break;
+		}
+	}
+	g_io_deliver(bp, 0);
+}
+
 static void
 g_concat_kernel_dump(struct bio *bp)
 {
@@ -327,6 +348,9 @@ g_concat_start(struct bio *bp)
 		if (strcmp("GEOM::kerneldump", bp->bio_attribute) == 0) {
 			g_concat_kernel_dump(bp);
 			return;
+		} else if (strcmp("GEOM::candelete", bp->bio_attribute) == 0) {
+			g_concat_candelete(bp);
+			return;
 		}
 		/* To which provider it should be delivered? */
 		/* FALLTHROUGH */
@@ -408,6 +432,7 @@ g_concat_check_and_run(struct g_concat_softc *sc)
 	struct g_provider *dp, *pp;
 	u_int no, sectorsize = 0;
 	off_t start;
+	int error;
 
 	g_topology_assert();
 	if (g_concat_nvalid(sc) != sc->sc_ndisks)
@@ -425,6 +450,16 @@ g_concat_check_and_run(struct g_concat_softc *sc)
 		if (sc->sc_type == G_CONCAT_TYPE_AUTOMATIC)
 			disk->d_end -= dp->sectorsize;
 		start = disk->d_end;
+		error = g_access(disk->d_consumer, 1, 0, 0);
+		if (error == 0) {
+			error = g_getattr("GEOM::candelete", disk->d_consumer,
+			    &disk->d_candelete);
+			if (error != 0)
+				disk->d_candelete = 0;
+			(void)g_access(disk->d_consumer, -1, 0, 0);
+		} else
+			G_CONCAT_DEBUG(1, "Failed to access disk %s, error %d.",
+			    dp->name, error);
 		if (no == 0)
 			sectorsize = dp->sectorsize;
 		else
diff --git a/sys/geom/concat/g_concat.h b/sys/geom/concat/g_concat.h
index 09cc554b1968..da7b6ff72202 100644
--- a/sys/geom/concat/g_concat.h
+++ b/sys/geom/concat/g_concat.h
@@ -74,6 +74,7 @@ struct g_concat_disk {
 	struct g_concat_softc	*d_softc;
 	off_t			 d_start;
 	off_t			 d_end;
+	int			 d_candelete;
 	int			 d_removed;
 };