Add an ability to stop gmirror and clear its metadata in one command.

This fixes the problem, when gmirror starts again just after stop.

The problem occurs when gmirror's component has geom label with equal size.
E.g. gpt and gptid have the same size as partition, diskid has the same
size as entire disk. When gmirror's geom has been destroyed, glabel
creates its providers and this initiate retaste.

Now "gmirror destroy" command is available. It destroys geom and also
erases gmirror's metadata.

MFC after:	2 weeks

2 files changed, 20 insertions, 1 deletions

diff --git a/sbin/geom/class/mirror/geom_mirror.c b/sbin/geom/class/mirror/geom_mirror.c
index 17cfccb..30f5f84 100644
--- a/sbin/geom/class/mirror/geom_mirror.c
+++ b/sbin/geom/class/mirror/geom_mirror.c
@@ -82,6 +82,13 @@ struct g_command class_commands[] = {
 	{ "deactivate", G_FLAG_VERBOSE, NULL, G_NULL_OPTS,
 	    "[-v] name prov ..."
 	},
+	{ "destroy", G_FLAG_VERBOSE, NULL,
+	    {
+		{ 'f', "force", NULL, G_TYPE_BOOL },
+		G_OPT_SENTINEL
+	    },
+	    "[-fv] name ..."
+	},
 	{ "dump", 0, mirror_main, G_NULL_OPTS,
 	    "prov ..."
 	},
diff --git a/sbin/geom/class/mirror/gmirror.8 b/sbin/geom/class/mirror/gmirror.8
index cabeac6..bb48eca 100644
--- a/sbin/geom/class/mirror/gmirror.8
+++ b/sbin/geom/class/mirror/gmirror.8
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 20, 2013
+.Dd December 27, 2013
 .Dt GMIRROR 8
 .Os
 .Sh NAME
@@ -86,6 +86,10 @@
 .Ar name
 .Ar prov ...
 .Nm
+.Cm destroy
+.Op Fl fv
+.Ar name ...
+.Nm
 .Cm forget
 .Op Fl v
 .Ar name ...
@@ -227,6 +231,14 @@ Activate the given component(s), which were marked as inactive before.
 .It Cm deactivate
 Mark the given component(s) as inactive, so it will not be automatically
 connected to the mirror.
+.It Cm destroy
+Stop the given mirror and clear metadata on all its components.
+.Pp
+Additional options include:
+.Bl -tag -width ".Fl f"
+.It Fl f
+Stop the given mirror even if it is opened.
+.El
 .It Cm forget
 Forget about components which are not connected.
 This command is useful when a disk has failed and cannot be reconnected, preventing the