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Date:      Tue, 1 Nov 2011 17:04:42 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r226998 - head/sys/geom/stripe
Message-ID:  <201111011704.pA1H4gmm076026@svn.freebsd.org>
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Author: mav
Date: Tue Nov  1 17:04:42 2011
New Revision: 226998
URL: http://svn.freebsd.org/changeset/base/226998

Log:
  Refactor disk disconnection and geom destruction handling sequences.
  Do not close/destroy opened consumer directly in case of disconnect. Instead
  keep it existing until it will be closed in regular way in response to
  upstream provider destruction. Delay geom destruction in the same way.
  Previous implementation could destroy consumers still having active
  requests and worked only because of global workaround made on GEOM level.

Modified:
  head/sys/geom/stripe/g_stripe.c

Modified: head/sys/geom/stripe/g_stripe.c
==============================================================================
--- head/sys/geom/stripe/g_stripe.c	Tue Nov  1 16:56:42 2011	(r226997)
+++ head/sys/geom/stripe/g_stripe.c	Tue Nov  1 17:04:42 2011	(r226998)
@@ -160,28 +160,35 @@ static void
 g_stripe_remove_disk(struct g_consumer *cp)
 {
 	struct g_stripe_softc *sc;
-	u_int no;
 
+	g_topology_assert();
 	KASSERT(cp != NULL, ("Non-valid disk in %s.", __func__));
-	sc = (struct g_stripe_softc *)cp->private;
+	sc = (struct g_stripe_softc *)cp->geom->softc;
 	KASSERT(sc != NULL, ("NULL sc in %s.", __func__));
-	no = cp->index;
 
-	G_STRIPE_DEBUG(0, "Disk %s removed from %s.", cp->provider->name,
-	    sc->sc_name);
+	if (cp->private == NULL) {
+		G_STRIPE_DEBUG(0, "Disk %s removed from %s.",
+		    cp->provider->name, sc->sc_name);
+		cp->private = (void *)(uintptr_t)-1;
+	}
 
-	sc->sc_disks[no] = NULL;
 	if (sc->sc_provider != NULL) {
 		sc->sc_provider->flags |= G_PF_WITHER;
+		G_STRIPE_DEBUG(0, "Device %s deactivated.",
+		    sc->sc_provider->name);
 		g_orphan_provider(sc->sc_provider, ENXIO);
 		sc->sc_provider = NULL;
-		G_STRIPE_DEBUG(0, "Device %s removed.", sc->sc_name);
 	}
 
 	if (cp->acr > 0 || cp->acw > 0 || cp->ace > 0)
-		g_access(cp, -cp->acr, -cp->acw, -cp->ace);
+		return;
+	sc->sc_disks[cp->index] = NULL;
+	cp->index = 0;
 	g_detach(cp);
 	g_destroy_consumer(cp);
+	/* If there are no valid disks anymore, remove device. */
+	if (LIST_EMPTY(&sc->sc_geom->consumer))
+		g_stripe_destroy(sc, 1);
 }
 
 static void
@@ -197,36 +204,20 @@ g_stripe_orphan(struct g_consumer *cp)
 		return;
 
 	g_stripe_remove_disk(cp);
-	/* If there are no valid disks anymore, remove device. */
-	if (g_stripe_nvalid(sc) == 0)
-		g_stripe_destroy(sc, 1);
 }
 
 static int
 g_stripe_access(struct g_provider *pp, int dr, int dw, int de)
 {
-	struct g_consumer *cp1, *cp2;
+	struct g_consumer *cp1, *cp2, *tmp;
 	struct g_stripe_softc *sc;
 	struct g_geom *gp;
 	int error;
 
+	g_topology_assert();
 	gp = pp->geom;
 	sc = gp->softc;
-
-	if (sc == NULL) {
-		/*
-		 * It looks like geom is being withered.
-		 * In that case we allow only negative requests.
-		 */
-		KASSERT(dr <= 0 && dw <= 0 && de <= 0,
-		    ("Positive access request (device=%s).", pp->name));
-		if ((pp->acr + dr) == 0 && (pp->acw + dw) == 0 &&
-		    (pp->ace + de) == 0) {
-			G_STRIPE_DEBUG(0, "Device %s definitely destroyed.",
-			    gp->name);
-		}
-		return (0);
-	}
+	KASSERT(sc != NULL, ("NULL sc in %s.", __func__));
 
 	/* On first open, grab an extra "exclusive" bit */
 	if (pp->acr == 0 && pp->acw == 0 && pp->ace == 0)
@@ -235,22 +226,23 @@ g_stripe_access(struct g_provider *pp, i
 	if ((pp->acr + dr) == 0 && (pp->acw + dw) == 0 && (pp->ace + de) == 0)
 		de--;
 
-	error = ENXIO;
-	LIST_FOREACH(cp1, &gp->consumer, consumer) {
+	LIST_FOREACH_SAFE(cp1, &gp->consumer, consumer, tmp) {
 		error = g_access(cp1, dr, dw, de);
-		if (error == 0)
-			continue;
-		/*
-		 * If we fail here, backout all previous changes.
-		 */
-		LIST_FOREACH(cp2, &gp->consumer, consumer) {
-			if (cp1 == cp2)
-				return (error);
-			g_access(cp2, -dr, -dw, -de);
+		if (error != 0)
+			goto fail;
+		if (cp1->acr == 0 && cp1->acw == 0 && cp1->ace == 0 &&
+		    cp1->private != NULL) {
+			g_stripe_remove_disk(cp1); /* May destroy geom. */
 		}
-		/* NOTREACHED */
 	}
+	return (0);
 
+fail:
+	LIST_FOREACH(cp2, &gp->consumer, consumer) {
+		if (cp1 == cp2)
+			break;
+		g_access(cp2, -dr, -dw, -de);
+	}
 	return (error);
 }
 
@@ -652,6 +644,7 @@ g_stripe_check_and_run(struct g_stripe_s
 	off_t mediasize, ms;
 	u_int no, sectorsize = 0;
 
+	g_topology_assert();
 	if (g_stripe_nvalid(sc) != sc->sc_ndisks)
 		return;
 
@@ -681,7 +674,7 @@ g_stripe_check_and_run(struct g_stripe_s
 	sc->sc_provider->stripeoffset = 0;
 	g_error_provider(sc->sc_provider, 0);
 
-	G_STRIPE_DEBUG(0, "Device %s activated.", sc->sc_name);
+	G_STRIPE_DEBUG(0, "Device %s activated.", sc->sc_provider->name);
 }
 
 static int
@@ -722,6 +715,7 @@ g_stripe_add_disk(struct g_stripe_softc 
 	struct g_geom *gp;
 	int error;
 
+	g_topology_assert();
 	/* Metadata corrupted? */
 	if (no >= sc->sc_ndisks)
 		return (EINVAL);
@@ -734,6 +728,8 @@ g_stripe_add_disk(struct g_stripe_softc 
 	fcp = LIST_FIRST(&gp->consumer);
 
 	cp = g_new_consumer(gp);
+	cp->private = NULL;
+	cp->index = no;
 	error = g_attach(cp, pp);
 	if (error != 0) {
 		g_destroy_consumer(cp);
@@ -764,12 +760,8 @@ g_stripe_add_disk(struct g_stripe_softc 
 		}
 	}
 
-	cp->private = sc;
-	cp->index = no;
 	sc->sc_disks[no] = cp;
-
 	G_STRIPE_DEBUG(0, "Disk %s attached to %s.", pp->name, sc->sc_name);
-
 	g_stripe_check_and_run(sc);
 
 	return (0);
@@ -789,6 +781,7 @@ g_stripe_create(struct g_class *mp, cons
 	struct g_geom *gp;
 	u_int no;
 
+	g_topology_assert();
 	G_STRIPE_DEBUG(1, "Creating device %s (id=%u).", md->md_name,
 	    md->md_id);
 
@@ -850,8 +843,8 @@ static int
 g_stripe_destroy(struct g_stripe_softc *sc, boolean_t force)
 {
 	struct g_provider *pp;
+	struct g_consumer *cp, *cp1;
 	struct g_geom *gp;
-	u_int no;
 
 	g_topology_assert();
 
@@ -871,24 +864,22 @@ g_stripe_destroy(struct g_stripe_softc *
 		}
 	}
 
-	for (no = 0; no < sc->sc_ndisks; no++) {
-		if (sc->sc_disks[no] != NULL)
-			g_stripe_remove_disk(sc->sc_disks[no]);
+	gp = sc->sc_geom;
+	LIST_FOREACH_SAFE(cp, &gp->consumer, consumer, cp1) {
+		g_stripe_remove_disk(cp);
+		if (cp1 == NULL)
+			return (0);	/* Recursion happened. */
 	}
+	if (!LIST_EMPTY(&gp->consumer))
+		return (EINPROGRESS);
 
-	gp = sc->sc_geom;
 	gp->softc = NULL;
 	KASSERT(sc->sc_provider == NULL, ("Provider still exists? (device=%s)",
 	    gp->name));
 	free(sc->sc_disks, M_STRIPE);
 	free(sc, M_STRIPE);
-
-	pp = LIST_FIRST(&gp->provider);
-	if (pp == NULL || (pp->acr == 0 && pp->acw == 0 && pp->ace == 0))
-		G_STRIPE_DEBUG(0, "Device %s destroyed.", gp->name);
-
+	G_STRIPE_DEBUG(0, "Device %s destroyed.", gp->name);
 	g_wither_geom(gp, ENXIO);
-
 	return (0);
 }

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