In addition to r258220 allow shrinking in "automatic" mode if there is

already valid metadata found at the new location.  This should allow easy
transparent recovery if first resize was done by mistake.

While there, unify metadata write code and fix minor memory leak.

MFC after:	1 month

1 files changed, 47 insertions, 35 deletions

diff --git a/sys/geom/multipath/g_multipath.c b/sys/geom/multipath/g_multipath.c
index f0e8aae3718a..88e65f8b2021 100644
--- a/sys/geom/multipath/g_multipath.c
+++ b/sys/geom/multipath/g_multipath.c
@@ -67,6 +67,11 @@ static enum {
 static struct bio_queue_head gmtbq;
 static struct mtx gmtbq_mtx;
 
+static int g_multipath_read_metadata(struct g_consumer *cp,
+    struct g_multipath_metadata *md);
+static int g_multipath_write_metadata(struct g_consumer *cp,
+    struct g_multipath_metadata *md);
+
 static void g_multipath_orphan(struct g_consumer *);
 static void g_multipath_resize(struct g_consumer *);
 static void g_multipath_start(struct bio *);
@@ -243,11 +248,11 @@ g_multipath_resize(struct g_consumer *cp)
 {
 	struct g_multipath_softc *sc;
 	struct g_geom *gp;
+	struct g_consumer *cp1;
 	struct g_provider *pp;
 	struct g_multipath_metadata md;
 	off_t size, psize, ssize;
 	int error;
-	void *buf;
 
 	g_topology_assert();
 
@@ -264,8 +269,8 @@ g_multipath_resize(struct g_consumer *cp)
 	} else {
 		size = ssize = OFF_MAX;
 		mtx_lock(&sc->sc_mtx);
-		LIST_FOREACH(cp, &gp->consumer, consumer) {
-			pp = cp->provider;
+		LIST_FOREACH(cp1, &gp->consumer, consumer) {
+			pp = cp1->provider;
 			if (pp == NULL)
 				continue;
 			if (pp->mediasize < size) {
@@ -280,36 +285,31 @@ g_multipath_resize(struct g_consumer *cp)
 	psize = size - ((sc->sc_uuid[0] != 0) ? ssize : 0);
 	printf("GEOM_MULTIPATH: %s size changed from %jd to %jd\n",
 	    sc->sc_name, sc->sc_pp->mediasize, psize);
-	if (sc->sc_uuid[0] != 0 && psize < sc->sc_pp->mediasize) {
-		g_multipath_destroy(gp);
-		return;
+	if (sc->sc_uuid[0] != 0 && size < sc->sc_size) {
+		error = g_multipath_read_metadata(cp, &md);
+		if (error ||
+		    (strcmp(md.md_magic, G_MULTIPATH_MAGIC) != 0) ||
+		    (memcmp(md.md_uuid, sc->sc_uuid, sizeof(sc->sc_uuid)) != 0) ||
+		    (strcmp(md.md_name, sc->sc_name) != 0) ||
+		    (md.md_size != 0 && md.md_size != size) ||
+		    (md.md_sectorsize != 0 && md.md_sectorsize != ssize)) {
+			g_multipath_destroy(gp);
+			return;
+		}
 	}
 	sc->sc_size = size;
 	g_resize_provider(sc->sc_pp, psize);
 
-	if (sc->sc_uuid[0] != 0 && sc->sc_active != NULL) {
-		cp = sc->sc_active;
+	if (sc->sc_uuid[0] != 0) {
 		pp = cp->provider;
-		error = g_access(cp, 1, 1, 1);
-		if (error != 0) {
-			printf("GEOM_MULTIPATH: Can't open %s (%d)\n",
-			    pp->name, error);
-			return;
-		}
-		g_topology_unlock();
-		buf = g_malloc(pp->sectorsize, M_WAITOK | M_ZERO);
 		strlcpy(md.md_magic, G_MULTIPATH_MAGIC, sizeof(md.md_magic));
 		memcpy(md.md_uuid, sc->sc_uuid, sizeof (sc->sc_uuid));
 		strlcpy(md.md_name, sc->sc_name, sizeof(md.md_name));
 		md.md_version = G_MULTIPATH_VERSION;
 		md.md_size = size;
-		md.md_sectorsize = pp->sectorsize;
+		md.md_sectorsize = ssize;
 		md.md_active_active = sc->sc_active_active;
-		multipath_metadata_encode(&md, buf);
-		error = g_write_data(cp, pp->mediasize - pp->sectorsize,
-		    buf, pp->sectorsize);
-		g_topology_lock();
-		g_access(cp, -1, -1, -1);
+		error = g_multipath_write_metadata(cp, &md);
 		if (error != 0)
 			printf("GEOM_MULTIPATH: Can't update metadata on %s "
 			    "(%d)\n", pp->name, error);
@@ -747,6 +747,30 @@ g_multipath_read_metadata(struct g_consumer *cp,
 	return (0);
 }
 
+static int
+g_multipath_write_metadata(struct g_consumer *cp,
+    struct g_multipath_metadata *md)
+{
+	struct g_provider *pp;
+	u_char *buf;
+	int error;
+
+	g_topology_assert();
+	error = g_access(cp, 1, 1, 1);
+	if (error != 0)
+		return (error);
+	pp = cp->provider;
+	g_topology_unlock();
+	buf = g_malloc(pp->sectorsize, M_WAITOK | M_ZERO);
+	multipath_metadata_encode(md, buf);
+	error = g_write_data(cp, pp->mediasize - pp->sectorsize,
+	    buf, pp->sectorsize);
+	g_topology_lock();
+	g_access(cp, -1, -1, -1);
+	g_free(buf);
+	return (error);
+}
+
 static struct g_geom *
 g_multipath_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
 {
@@ -1109,7 +1133,6 @@ g_multipath_ctl_configure(struct gctl_req *req, struct g_class *mp)
 	struct g_multipath_metadata md;
 	const char *name;
 	int error, *val;
-	void *buf;
 
 	g_topology_assert();
 
@@ -1136,13 +1159,6 @@ g_multipath_ctl_configure(struct gctl_req *req, struct g_class *mp)
 	if (sc->sc_uuid[0] != 0 && sc->sc_active != NULL) {
 		cp = sc->sc_active;
 		pp = cp->provider;
-		error = g_access(cp, 1, 1, 1);
-		if (error != 0) {
-			gctl_error(req, "Can't open %s (%d)", pp->name, error);
-			return;
-		}
-		g_topology_unlock();
-		buf = g_malloc(pp->sectorsize, M_WAITOK | M_ZERO);
 		strlcpy(md.md_magic, G_MULTIPATH_MAGIC, sizeof(md.md_magic));
 		memcpy(md.md_uuid, sc->sc_uuid, sizeof (sc->sc_uuid));
 		strlcpy(md.md_name, name, sizeof(md.md_name));
@@ -1150,11 +1166,7 @@ g_multipath_ctl_configure(struct gctl_req *req, struct g_class *mp)
 		md.md_size = pp->mediasize;
 		md.md_sectorsize = pp->sectorsize;
 		md.md_active_active = sc->sc_active_active;
-		multipath_metadata_encode(&md, buf);
-		error = g_write_data(cp, pp->mediasize - pp->sectorsize,
-		    buf, pp->sectorsize);
-		g_topology_lock();
-		g_access(cp, -1, -1, -1);
+		error = g_multipath_write_metadata(cp, &md);
 		if (error != 0)
 			gctl_error(req, "Can't update metadata on %s (%d)",
 			    pp->name, error);