Revert "Fix ZFS deadlock on db_mtx and dn_holds"

This reverts commit 7a32fe7c6b7a86962c5d2db2bf2e58b9b65cb921.
ClusterHQ · Oct 6, 2015 · 3bb6fd0 · 3bb6fd0
1 parent 387d61b
commit 3bb6fd0
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Showing 2 changed files with 7 additions and 25 deletions.
diff --git a/include/sys/dbuf.h b/include/sys/dbuf.h
@@ -195,14 +195,6 @@ typedef struct dmu_buf_impl {
 	 */
 	uint8_t db_level;
 
-	/*
-	 * db_user_mtx protects the two members below it.
-	 * stuff we store for the user (see dmu_buf_set_user)
-	 */
-	kmutex_t db_user_mtx;
-	void *db_user_ptr;
-	dmu_buf_evict_func_t *db_evict_func;
-
 	/* db_mtx protects the members below */
 	kmutex_t db_mtx;
 
@@ -235,6 +227,10 @@ typedef struct dmu_buf_impl {
 
 	/* Data which is unique to data (leaf) blocks: */
 
+	/* stuff we store for the user (see dmu_buf_set_user) */
+	void *db_user_ptr;
+	dmu_buf_evict_func_t *db_evict_func;
+
 	uint8_t db_immediate_evict;
 	uint8_t db_freed_in_flight;
 

diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
@@ -91,7 +91,6 @@ dbuf_cons(void *vdb, void *unused, int kmflag)
 	dmu_buf_impl_t *db = vdb;
 	bzero(db, sizeof (dmu_buf_impl_t));
 
-	mutex_init(&db->db_user_mtx, NULL, MUTEX_DEFAULT, NULL);
 	mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
 	cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
 	refcount_create(&db->db_holds);
@@ -104,7 +103,6 @@ static void
 dbuf_dest(void *vdb, void *unused)
 {
 	dmu_buf_impl_t *db = vdb;
-	mutex_destroy(&db->db_user_mtx);
 	mutex_destroy(&db->db_mtx);
 	cv_destroy(&db->db_changed);
 	refcount_destroy(&db->db_holds);
@@ -270,24 +268,12 @@ dbuf_evict_user(dmu_buf_impl_t *db)
 {
 	ASSERT(MUTEX_HELD(&db->db_mtx));
 
-	if (db->db_level != 0)
+	if (db->db_level != 0 || db->db_evict_func == NULL)
 		return;
 
-	mutex_enter(&db->db_user_mtx);
-	mutex_exit(&db->db_mtx);
-
-	if (db->db_evict_func == NULL) {
-		mutex_exit(&db->db_user_mtx);
-		mutex_enter(&db->db_mtx);
-		return;
-	}
-
 	db->db_evict_func(&db->db, db->db_user_ptr);
 	db->db_user_ptr = NULL;
 	db->db_evict_func = NULL;
-
-	mutex_exit(&db->db_user_mtx);
-	mutex_enter(&db->db_mtx);
 }
 
 boolean_t
@@ -2407,7 +2393,7 @@ dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr,
 
 	ASSERT((user_ptr == NULL) == (evict_func == NULL));
 
-	mutex_enter(&db->db_user_mtx);
+	mutex_enter(&db->db_mtx);
 
 	if (db->db_user_ptr == old_user_ptr) {
 		db->db_user_ptr = user_ptr;
@@ -2416,7 +2402,7 @@ dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr,
 		old_user_ptr = db->db_user_ptr;
 	}
 
-	mutex_exit(&db->db_user_mtx);
+	mutex_exit(&db->db_mtx);
 	return (old_user_ptr);
 }