Add a very simple but functional GEOM mirror class.

This is committed more as an instructive tool than as a production
facility, but this will change over time.

1 files changed, 250 insertions, 0 deletions

diff --git a/sys/geom/geom_mirror.c b/sys/geom/geom_mirror.c
new file mode 100644
index 0000000..23e2f52
--- /dev/null
+++ b/sys/geom/geom_mirror.c
@@ -0,0 +1,250 @@
+/*-
+ * Copyright (c) 2003 Poul-Henning Kamp
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the authors may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ *
+ */
+
+#include <sys/param.h>
+#ifndef _KERNEL
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <err.h>
+#else
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/conf.h>
+#include <sys/bio.h>
+#include <sys/malloc.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/libkern.h>
+#endif
+#include <sys/endian.h>
+#include <sys/md5.h>
+#include <sys/errno.h>
+#include <geom/geom.h>
+
+#define MIRROR_MAGIC	"GEOM::MIRROR"
+
+struct g_mirror_softc {
+	off_t	mediasize;
+	u_int	sectorsize;
+	u_char magic[16];
+};
+
+
+static int
+g_mirror_add(struct g_geom *gp, struct g_provider *pp)
+{
+	struct g_consumer *cp;
+
+	g_trace(G_T_TOPOLOGY, "g_mirror_add(%s, %s)", gp->name, pp->name);
+	g_topology_assert();
+	cp = g_new_consumer(gp);
+	g_attach(cp, pp);
+	return (0);
+}
+
+static void
+g_mirror_orphan(struct g_consumer *cp)
+{
+	struct g_geom *gp;
+	struct g_provider *pp;
+
+	g_topology_assert();
+	gp = cp->geom;
+	g_access_rel(cp, -cp->acr, -cp->acw, -cp->ace);
+	g_detach(cp);
+	g_destroy_consumer(cp);	
+	if (!LIST_EMPTY(&gp->consumer))
+		return;
+	LIST_FOREACH(pp, &gp->provider, provider)
+		g_orphan_provider(pp, ENXIO);
+	g_free(gp->softc);
+	gp->flags |= G_GEOM_WITHER;
+}
+
+static void
+g_mirror_done(struct bio *bp)
+{
+	struct g_geom *gp;
+	struct g_mirror_softc *sc;
+	struct g_consumer *cp;
+
+	gp = bp->bio_to->geom;
+	sc = gp->softc;
+	cp = LIST_NEXT(bp->bio_from, consumer);
+	if (cp == NULL)
+		g_std_done(bp);
+	else
+		g_io_request(bp, cp);
+}
+
+static void
+g_mirror_start(struct bio *bp)
+{
+	struct g_geom *gp;
+	struct bio *bp2;
+	struct g_mirror_softc *sc;
+
+	gp = bp->bio_to->geom;
+	sc = gp->softc;
+	switch(bp->bio_cmd) {
+	case BIO_READ:
+		bp2 = g_clone_bio(bp);
+		bp2->bio_offset += sc->sectorsize;
+		bp2->bio_done = g_std_done;
+		g_io_request(bp2, LIST_FIRST(&gp->consumer));
+		return;
+	case BIO_WRITE:
+	case BIO_DELETE:
+		bp2 = g_clone_bio(bp);
+		bp2->bio_offset += sc->sectorsize;
+		bp2->bio_done = g_mirror_done;
+		g_io_request(bp2, LIST_FIRST(&gp->consumer));
+		return;
+	default:
+		g_io_deliver(bp, EOPNOTSUPP);
+		return;
+	}
+}
+
+static int
+g_mirror_access(struct g_provider *pp, int dr, int dw, int de)
+{
+	struct g_geom *gp;
+	struct g_consumer *cp1, *cp2;
+	int error;
+
+	de += dr;
+	de += dw;
+
+	gp = pp->geom;
+	error = ENXIO;
+	LIST_FOREACH(cp1, &gp->consumer, consumer) {
+		error = g_access_rel(cp1, dr, dw, de);
+		if (error) {
+			LIST_FOREACH(cp2, &gp->consumer, consumer) {
+				if (cp2 == cp1)
+					break;
+				g_access_rel(cp2, -dr, -dw, -de);
+			}
+			return (error);
+		}
+	}
+	return (error);
+}
+
+static struct g_geom *
+g_mirror_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
+{
+	struct g_geom *gp, *gp2;
+	struct g_provider *pp2;
+	struct g_consumer *cp;
+	struct g_mirror_softc *sc;
+	int error;
+	u_int sectorsize;
+	u_char *buf;
+
+	g_trace(G_T_TOPOLOGY, "mirror_taste(%s, %s)", mp->name, pp->name);
+	g_topology_assert();
+	gp = g_new_geomf(mp, "%s.mirror", pp->name);
+
+	gp->start = g_mirror_start;
+	gp->spoiled = g_mirror_orphan;
+	gp->orphan = g_mirror_orphan;
+	gp->access= g_mirror_access;
+	cp = g_new_consumer(gp);
+	g_attach(cp, pp);
+	error = g_access_rel(cp, 1, 0, 0);
+	if (error) {
+		g_detach(cp);
+		g_destroy_consumer(cp);	
+		g_destroy_geom(gp);
+		return(NULL);
+	}
+	g_topology_unlock();
+	while (1) {
+		sectorsize = cp->provider->sectorsize;
+		buf = g_read_data(cp, 0, sectorsize, &error);
+		if (buf == NULL || error != 0)
+			break;
+		if (memcmp(buf, MIRROR_MAGIC, strlen(MIRROR_MAGIC)))
+			break;
+		LIST_FOREACH(gp2, &mp->geom, geom) {
+			sc = gp2->softc;
+			if (sc == NULL)
+				continue;
+			if (memcmp(buf + 16, sc->magic, sizeof sc->magic))
+				continue;
+			break;
+		}
+		/* We found somebody else */
+		if (gp2 != NULL) {
+			g_topology_lock();
+			g_mirror_add(gp2, pp);
+			g_topology_unlock();
+			break;
+		}
+		gp->softc = g_malloc(sizeof(struct g_mirror_softc), M_WAITOK);
+		sc = gp->softc;
+		memcpy(sc->magic, buf + 16, sizeof sc->magic);
+		g_topology_lock();
+		pp2 = g_new_providerf(gp, "%s", gp->name);
+		pp2->mediasize = sc->mediasize = pp->mediasize - pp->sectorsize;
+		pp2->sectorsize = sc->sectorsize = pp->sectorsize;
+		g_error_provider(pp2, 0);
+		g_topology_unlock();
+		
+		break;
+	}
+	g_topology_lock();
+	if (buf != NULL)
+		g_free(buf);
+	g_access_rel(cp, -1, 0, 0);
+	if (gp->softc != NULL)
+		return (gp);
+	g_detach(cp);
+	g_destroy_consumer(cp);
+	g_destroy_geom(gp);
+	return (NULL);
+}
+
+#define MIRROR_CLASS_NAME "MIRROR"
+
+static struct g_class g_mirror_class	= {
+	MIRROR_CLASS_NAME,
+	g_mirror_taste,
+	NULL,
+	G_CLASS_INITIALIZER
+};
+
+DECLARE_GEOM_CLASS(g_mirror_class, g_mirror);