Illumos 4168, 4169, 4170: ztest, zdb and zhack fixes

4168 ztest assertion failure in dbuf_undirty
4169 verbatim import causes zdb to segfault
4170 zhack leaves pool in ACTIVE state
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@nexenta.com>

References:
    https://www.illumos.org/issues/4168
    https://www.illumos.org/issues/4169
    https://www.illumos.org/issues/4170
    https://github.com/illumos/illumos-gate/commit/7fdd916

Porting notes:

Of particular interest when troubleshooting corrupted pools, the
commonly-used "zdb -e" operation may perform verbatim imports and
furthermore, it will soon have direct support for verbatim imports via
a new "-V" option.  The 4169 fix eliminates a common segfault case in
which spa_history_log_version() tries to access an un-opened dsl_pool_t.

Ported by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2451
Closes #2283
Closes #2467

cmd/zhack/zhack.c

@@ -20,7 +20,7 @@
  */
 
 /*
- * Copyright (c) 2012 by Delphix. All rights reserved.
+ * Copyright (c) 2013 by Delphix. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  */
 
@@ -84,10 +84,15 @@ usage(void)
 
 
 static void
-fatal(const char *fmt, ...)
+fatal(spa_t *spa, void *tag, const char *fmt, ...)
 {
 	va_list ap;
 
+	if (spa != NULL) {
+		spa_close(spa, tag);
+		(void) spa_export(g_pool, NULL, B_TRUE, B_FALSE);
+	}
+
 	va_start(ap, fmt);
 	(void) fprintf(stderr, "%s: ", cmdname);
 	(void) vfprintf(stderr, fmt, ap);
@@ -158,13 +163,14 @@ import_pool(const char *target, boolean_t readonly)
 			g_importargs.can_be_active = B_TRUE;
 			if (zpool_search_import(g_zfs, &g_importargs) != NULL ||
 			    spa_open(target, &spa, FTAG) == 0) {
-				fatal("cannot import '%s': pool is active; run "
+				fatal(spa, FTAG, "cannot import '%s': pool is "
-				    "\"zpool export %s\" first\n",
+				    "active; run " "\"zpool export %s\" "
-				    g_pool, g_pool);
+				    "first\n", g_pool, g_pool);
 			}
 		}
 
-		fatal("cannot import '%s': no such pool available\n", g_pool);
+		fatal(NULL, FTAG, "cannot import '%s': no such pool "
+		    "available\n", g_pool);
 	}
 
 	elem = nvlist_next_nvpair(pools, NULL);
@@ -185,7 +191,8 @@ import_pool(const char *target, boolean_t readonly)
 		error = 0;
 
 	if (error)
-		fatal("can't import '%s': %s", name, strerror(error));
+		fatal(NULL, FTAG, "can't import '%s': %s", name,
+		    strerror(error));
 }
 
 static void
@@ -200,10 +207,11 @@ zhack_spa_open(const char *target, boolean_t readonly, void *tag, spa_t **spa)
 	zfeature_checks_disable = B_FALSE;
 
 	if (err != 0)
-		fatal("cannot open '%s': %s", target, strerror(err));
+		fatal(*spa, FTAG, "cannot open '%s': %s", target,
+		    strerror(err));
 	if (spa_version(*spa) < SPA_VERSION_FEATURES) {
-		fatal("'%s' has version %d, features not enabled", target,
+		fatal(*spa, FTAG, "'%s' has version %d, features not enabled",
-		    (int)spa_version(*spa));
+		    target, (int)spa_version(*spa));
 	}
 }
 
@@ -336,15 +344,16 @@ zhack_do_feature_enable(int argc, char **argv)
 	feature.fi_guid = argv[1];
 
 	if (!zfeature_is_valid_guid(feature.fi_guid))
-		fatal("invalid feature guid: %s", feature.fi_guid);
+		fatal(NULL, FTAG, "invalid feature guid: %s", feature.fi_guid);
 
 	zhack_spa_open(target, B_FALSE, FTAG, &spa);
 	mos = spa->spa_meta_objset;
 
 	if (0 == zfeature_lookup_guid(feature.fi_guid, NULL))
-		fatal("'%s' is a real feature, will not enable");
+		fatal(spa, FTAG, "'%s' is a real feature, will not enable");
 	if (0 == zap_contains(mos, spa->spa_feat_desc_obj, feature.fi_guid))
-		fatal("feature already enabled: %s", feature.fi_guid);
+		fatal(spa, FTAG, "feature already enabled: %s",
+		    feature.fi_guid);
 
 	VERIFY0(dsl_sync_task(spa_name(spa), NULL,
 	    feature_enable_sync, &feature, 5));
@@ -423,13 +432,14 @@ zhack_do_feature_ref(int argc, char **argv)
 	feature.fi_guid = argv[1];
 
 	if (!zfeature_is_valid_guid(feature.fi_guid))
-		fatal("invalid feature guid: %s", feature.fi_guid);
+		fatal(NULL, FTAG, "invalid feature guid: %s", feature.fi_guid);
 
 	zhack_spa_open(target, B_FALSE, FTAG, &spa);
 	mos = spa->spa_meta_objset;
 
 	if (0 == zfeature_lookup_guid(feature.fi_guid, NULL))
-		fatal("'%s' is a real feature, will not change refcount");
+		fatal(spa, FTAG, "'%s' is a real feature, will not change "
+		    "refcount");
 
 	if (0 == zap_contains(mos, spa->spa_feat_for_read_obj,
 	    feature.fi_guid)) {
@@ -438,11 +448,12 @@ zhack_do_feature_ref(int argc, char **argv)
 	    feature.fi_guid)) {
 		feature.fi_can_readonly = B_TRUE;
 	} else {
-		fatal("feature is not enabled: %s", feature.fi_guid);
+		fatal(spa, FTAG, "feature is not enabled: %s", feature.fi_guid);
 	}
 
 	if (decr && !spa_feature_is_active(spa, &feature))
-		fatal("feature refcount already 0: %s", feature.fi_guid);
+		fatal(spa, FTAG, "feature refcount already 0: %s",
+		    feature.fi_guid);
 
 	VERIFY0(dsl_sync_task(spa_name(spa), NULL,
 	    decr ? feature_decr_sync : feature_incr_sync, &feature, 5));
@@ -530,8 +541,8 @@ main(int argc, char **argv)
 		usage();
 	}
 
-	if (!g_readonly && spa_export(g_pool, NULL, B_TRUE, B_TRUE) != 0) {
+	if (!g_readonly && spa_export(g_pool, NULL, B_TRUE, B_FALSE) != 0) {
-		fatal("pool export failed; "
+		fatal(NULL, FTAG, "pool export failed; "
 		    "changes may not be committed to disk\n");
 	}
 

module/zfs/dbuf.c

@@ -1391,14 +1391,6 @@ dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
 	DB_DNODE_ENTER(db);
 	dn = DB_DNODE(db);
 
-	/*
-	 * Note:  This code will probably work even if there are concurrent
-	 * holders, but it is untested in that scenerio, as the ZPL and
-	 * ztest have additional locking (the range locks) that prevents
-	 * that type of concurrent access.
-	 */
-	ASSERT3U(refcount_count(&db->db_holds), ==, db->db_dirtycnt);
-
 	dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
 
 	ASSERT(db->db.db_size != 0);

module/zfs/spa.c

@@ -3901,8 +3901,6 @@ spa_import(char *pool, nvlist_t *config, nvlist_t *props, uint64_t flags)
 		spa_config_sync(spa, B_FALSE, B_TRUE);
 
 		mutex_exit(&spa_namespace_lock);
-		spa_history_log_version(spa, "import");
-
 		return (0);
 	}