From 8488e4961e9264865a12c05eb56783746541c717 Mon Sep 17 00:00:00 2001
From: ae <ae@FreeBSD.org>
Date: Sun, 4 May 2014 16:43:57 +0000
Subject: Prevent an unexpected shrinking on resizing due to alignment for MBR,
 PC98 and VTOC8 schemes.

Reported by:	jmg
MFC after:	1 week
---
 sys/geom/part/g_part_mbr.c   | 7 ++++++-
 sys/geom/part/g_part_pc98.c  | 7 ++++++-
 sys/geom/part/g_part_vtoc8.c | 7 ++++++-
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/sys/geom/part/g_part_mbr.c b/sys/geom/part/g_part_mbr.c
index 55fc789..f9f06be 100644
--- a/sys/geom/part/g_part_mbr.c
+++ b/sys/geom/part/g_part_mbr.c
@@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/sysctl.h>
 #include <geom/geom.h>
+#include <geom/geom_int.h>
 #include <geom/part/g_part.h>
 
 #include "g_part_if.h"
@@ -353,7 +354,11 @@ g_part_mbr_resize(struct g_part_table *basetable,
 	size = gpp->gpp_size;
 	if (mbr_align(basetable, NULL, &size) != 0)
 		return (EINVAL);
-
+	/* XXX: prevent unexpected shrinking. */
+	pp = baseentry->gpe_pp;
+	if ((g_debugflags & 16) == 0 && size < gpp->gpp_size &&
+	    (pp->acr > 0 || pp->acw > 0 || pp->ace > 0))
+		return (EBUSY);
 	entry = (struct g_part_mbr_entry *)baseentry;
 	baseentry->gpe_end = baseentry->gpe_start + size - 1;
 	entry->ent.dp_size = size;
diff --git a/sys/geom/part/g_part_pc98.c b/sys/geom/part/g_part_pc98.c
index 9fc6b2a..b2b6e68 100644
--- a/sys/geom/part/g_part_pc98.c
+++ b/sys/geom/part/g_part_pc98.c
@@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/sysctl.h>
 #include <geom/geom.h>
+#include <geom/geom_int.h>
 #include <geom/part/g_part.h>
 
 #include "g_part_if.h"
@@ -360,7 +361,11 @@ g_part_pc98_resize(struct g_part_table *basetable,
 	size = gpp->gpp_size;
 	if (pc98_align(basetable, NULL, &size) != 0)
 		return (EINVAL);
-
+	/* XXX: prevent unexpected shrinking. */
+	pp = baseentry->gpe_pp;
+	if ((g_debugflags & 0x10) == 0 && size < gpp->gpp_size &&
+	    (pp->acr > 0 || pp->acw > 0 || pp->ace > 0))
+		return (EBUSY);
 	entry = (struct g_part_pc98_entry *)baseentry;
 	baseentry->gpe_end = baseentry->gpe_start + size - 1;
 	pc98_set_chs(basetable, baseentry->gpe_end, &entry->ent.dp_ecyl,
diff --git a/sys/geom/part/g_part_vtoc8.c b/sys/geom/part/g_part_vtoc8.c
index f40052b..04d90cb 100644
--- a/sys/geom/part/g_part_vtoc8.c
+++ b/sys/geom/part/g_part_vtoc8.c
@@ -42,6 +42,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysctl.h>
 #include <sys/vtoc.h>
 #include <geom/geom.h>
+#include <geom/geom_int.h>
 #include <geom/part/g_part.h>
 
 #include "g_part_if.h"
@@ -367,7 +368,11 @@ g_part_vtoc8_resize(struct g_part_table *basetable,
 	size = gpp->gpp_size;
 	if (vtoc8_align(table, NULL, &size) != 0)
 		return (EINVAL);
-
+	/* XXX: prevent unexpected shrinking. */
+	pp = entry->gpe_pp;
+	if ((g_debugflags & 0x10) == 0 && size < gpp->gpp_size &&
+	    (pp->acr > 0 || pp->acw > 0 || pp->ace > 0))
+		return (EBUSY);
 	entry->gpe_end = entry->gpe_start + size - 1;
 	be32enc(&table->vtoc.map[entry->gpe_index - 1].nblks, size);
 
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