Serialize access to spa->spa_feat_stats nvlist

The function spa_add_feature_stats() manipulates the shared nvlist spa->spa_feat_stats in an unsafe concurrent manner. Add a mutex to protect the list. Signed-off-by: Ned Bass <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3335
openzfs · Jun 23, 2015 · 464c506 · 464c506
1 parent 71fa174
commit 464c506
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Showing 3 changed files with 9 additions and 1 deletion.
diff --git a/include/sys/spa_impl.h b/include/sys/spa_impl.h
@@ -236,6 +236,7 @@ struct spa {
 	uint64_t	spa_feat_for_read_obj;	/* required to read from pool */
 	uint64_t	spa_feat_desc_obj;	/* Feature descriptions */
 	uint64_t	spa_feat_enabled_txg_obj; /* Feature enabled txg */
+	kmutex_t	spa_feat_stats_lock;	/* protects spa_feat_stats */
 	nvlist_t	*spa_feat_stats;	/* Cache of enabled features */
 	/* cache feature refcounts */
 	uint64_t	spa_feat_refcount_cache[SPA_FEATURES];

diff --git a/module/zfs/spa.c b/module/zfs/spa.c
@@ -3264,10 +3264,13 @@ spa_feature_stats_from_cache(spa_t *spa, nvlist_t *features)
 static void
 spa_add_feature_stats(spa_t *spa, nvlist_t *config)
 {
-	nvlist_t *features = spa->spa_feat_stats;
+	nvlist_t *features;
 
 	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER));
 
+	mutex_enter(&spa->spa_feat_stats_lock);
+	features = spa->spa_feat_stats;
+
 	if (features != NULL) {
 		spa_feature_stats_from_cache(spa, features);
 	} else {
@@ -3278,6 +3281,8 @@ spa_add_feature_stats(spa_t *spa, nvlist_t *config)
 
 	VERIFY0(nvlist_add_nvlist(config, ZPOOL_CONFIG_FEATURE_STATS,
 	    features));
+
+	mutex_exit(&spa->spa_feat_stats_lock);
 }
 
 int

diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
@@ -531,6 +531,7 @@ spa_add(const char *name, nvlist_t *config, const char *altroot)
 	mutex_init(&spa->spa_scrub_lock, NULL, MUTEX_DEFAULT, NULL);
 	mutex_init(&spa->spa_suspend_lock, NULL, MUTEX_DEFAULT, NULL);
 	mutex_init(&spa->spa_vdev_top_lock, NULL, MUTEX_DEFAULT, NULL);
+	mutex_init(&spa->spa_feat_stats_lock, NULL, MUTEX_DEFAULT, NULL);
 
 	cv_init(&spa->spa_async_cv, NULL, CV_DEFAULT, NULL);
 	cv_init(&spa->spa_proc_cv, NULL, CV_DEFAULT, NULL);
@@ -668,6 +669,7 @@ spa_remove(spa_t *spa)
 	mutex_destroy(&spa->spa_scrub_lock);
 	mutex_destroy(&spa->spa_suspend_lock);
 	mutex_destroy(&spa->spa_vdev_top_lock);
+	mutex_destroy(&spa->spa_feat_stats_lock);
 
 	kmem_free(spa, sizeof (spa_t));
 }