svn commit: r361838 - in head/sys/geom: . label

Conrad Meyer cem at FreeBSD.org
Fri Jun 5 16:12:22 UTC 2020


Author: cem
Date: Fri Jun  5 16:12:21 2020
New Revision: 361838
URL: https://svnweb.freebsd.org/changeset/base/361838

Log:
  geom_label: Use provider aliasing to alias upstream geoms
  
  For synthetic aliases (just pseudonyms inferred from metadata like GPT or
  UFS labels, GPT UUIDs, etc), use the GEOM provider aliasing system to create
  a symlink to the real device instead of creating an independent device.
  This makes it more clear which labels and devices correspond, and we can
  safely have multiple labels to a single device accessed at once.
  
  The confusingly named geom_label on-disk construct continues to behave
  identically to how it did before.
  
  This requires teaching GEOM's provider aliasing about the possibility
  that aliases might be added later in time, and GEOM's devfs interaction
  layer not to worry about existing aliases during retaste.
  
  Discussed with:	imp
  Relnotes:	sure, if we don't end up reverting it
  Differential Revision:	https://reviews.freebsd.org/D24968

Modified:
  head/sys/geom/geom_dev.c
  head/sys/geom/label/g_label.c

Modified: head/sys/geom/geom_dev.c
==============================================================================
--- head/sys/geom/geom_dev.c	Fri Jun  5 16:05:09 2020	(r361837)
+++ head/sys/geom/geom_dev.c	Fri Jun  5 16:12:21 2020	(r361838)
@@ -336,9 +336,20 @@ g_dev_taste(struct g_class *mp, struct g_provider *pp,
 	struct cdev *dev, *adev;
 	char buf[SPECNAMELEN + 6];
 	struct make_dev_args args;
+	bool retaste;
 
 	g_trace(G_T_TOPOLOGY, "dev_taste(%s,%s)", mp->name, pp->name);
 	g_topology_assert();
+	/* Only one geom_dev per provider. */
+	LIST_FOREACH(cp, &pp->consumers, consumers) {
+		if (cp->geom->class != mp || (cp->flags & G_CF_SPOILED))
+			continue;
+		gp = cp->geom;
+		sc = cp->private;
+		dev = sc->sc_dev;
+		retaste = true;
+		goto aliases;
+	}
 	gp = g_new_geomf(mp, "%s", pp->name);
 	sc = g_malloc(sizeof(*sc), M_WAITOK | M_ZERO);
 	mtx_init(&sc->sc_mtx, "g_dev", NULL, MTX_DEF);
@@ -380,6 +391,8 @@ g_dev_taste(struct g_class *mp, struct g_provider *pp,
 	g_dev_attrchanged(cp, "GEOM::physpath");
 	snprintf(buf, sizeof(buf), "cdev=%s", gp->name);
 	devctl_notify_f("GEOM", "DEV", "CREATE", buf, M_WAITOK);
+	retaste = false;
+aliases:
 	/*
 	 * Now add all the aliases for this drive
 	 */
@@ -387,8 +400,16 @@ g_dev_taste(struct g_class *mp, struct g_provider *pp,
 		error = make_dev_alias_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK, &adev, dev,
 		    "%s", gap->ga_alias);
 		if (error) {
-			printf("%s: make_dev_alias_p() failed (name=%s, error=%d)\n",
-			    __func__, gap->ga_alias, error);
+			/*
+			 * With aliases added after initial taste, we don't
+			 * know which aliases are new in this retaste, so we
+			 * try to create all of them.  EEXIST is expected and
+			 * silently ignored or else this becomes really spammy.
+			 */
+			if (error != EEXIST || !retaste)
+				printf("%s: make_dev_alias_p() failed (name=%s,"
+				    " error=%d)\n", __func__, gap->ga_alias,
+				    error);
 			continue;
 		}
 		snprintf(buf, sizeof(buf), "cdev=%s", gap->ga_alias);

Modified: head/sys/geom/label/g_label.c
==============================================================================
--- head/sys/geom/label/g_label.c	Fri Jun  5 16:05:09 2020	(r361837)
+++ head/sys/geom/label/g_label.c	Fri Jun  5 16:12:21 2020	(r361838)
@@ -46,6 +46,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/sysctl.h>
 #include <geom/geom.h>
 #include <geom/geom_dbg.h>
+#include <geom/geom_int.h>
 #include <geom/geom_slice.h>
 #include <geom/label/g_label.h>
 
@@ -344,18 +345,16 @@ g_label_taste(struct g_class *mp, struct g_provider *p
 {
 	struct g_label_metadata md;
 	struct g_consumer *cp;
+	struct g_class *clsp;
 	struct g_geom *gp;
 	int i;
+	bool changed;
 
 	g_trace(G_T_TOPOLOGY, "%s(%s, %s)", __func__, mp->name, pp->name);
 	g_topology_assert();
 
 	G_LABEL_DEBUG(2, "Tasting %s.", pp->name);
 
-	/* Skip providers that are already open for writing. */
-	if (pp->acw > 0)
-		return (NULL);
-
 	if (strcmp(pp->geom->class->name, mp->name) == 0)
 		return (NULL);
 
@@ -391,9 +390,16 @@ g_label_taste(struct g_class *mp, struct g_provider *p
 		if (md.md_provsize != pp->mediasize)
 			break;
 
+		/* Skip providers that are already open for writing. */
+		if (pp->acw > 0) {
+			g_access(cp, -1, 0, 0);
+			goto end;
+		}
+
 		g_label_create(NULL, mp, pp, md.md_label, G_LABEL_DIR,
 		    pp->mediasize - pp->sectorsize);
 	} while (0);
+	changed = false;
 	for (i = 0; g_labels[i] != NULL; i++) {
 		char label[128];
 
@@ -405,8 +411,28 @@ g_label_taste(struct g_class *mp, struct g_provider *p
 		g_topology_lock();
 		if (label[0] == '\0')
 			continue;
-		g_label_create(NULL, mp, pp, label, g_labels[i]->ld_dir,
-		    pp->mediasize);
+		if (!g_label_is_name_ok(label)) {
+			G_LABEL_DEBUG(0,
+			    "%s contains suspicious label, skipping.",
+			    pp->name);
+			G_LABEL_DEBUG(1, "%s suspicious label is: %s",
+			    pp->name, label);
+			continue;
+		}
+		g_provider_add_alias(pp, "%s/%s", g_labels[i]->ld_dir, label);
+		changed = true;
+	}
+	/*
+	 * Force devfs interface to retaste the provider, to catch the new
+	 * alias(es).
+	 */
+	if (changed) {
+		LIST_FOREACH(clsp, &g_classes, class) {
+			if (strcmp(clsp->name, "DEV") != 0)
+				continue;
+			clsp->taste(clsp, pp, 0);
+			break;
+		}
 	}
 	g_access(cp, -1, 0, 0);
 end:


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