Revert "Add zio constructor/destructor"

This patch was slightly flawed and allowed for zio->io_logical
to potentially not be reinitialized for a new zio.  This could
lead to assertion failures in specific cases when debugging is
enabled (--enable-debug) and I/O errors are encountered.  It
may also have caused problems when issues logical I/Os.

Since we want to make sure this workaround can be easily removed
in the future (when we have the real fix).  I'm reverting this
change and applying a new version of the patch which includes
the zio->io_logical fix.

This reverts commit 2c6d0b1.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #602
Issue #604

module/zfs/zio.c

@@ -99,35 +99,6 @@ int zio_buf_debug_limit = 0;
 
 static inline void __zio_execute(zio_t *zio);
 
-static int
-zio_cons(void *arg, void *unused, int kmflag)
-{
-	zio_t *zio = arg;
-
-	bzero(zio, sizeof (zio_t));
-
-	mutex_init(&zio->io_lock, NULL, MUTEX_DEFAULT, NULL);
-	cv_init(&zio->io_cv, NULL, CV_DEFAULT, NULL);
-
-	list_create(&zio->io_parent_list, sizeof (zio_link_t),
-	    offsetof(zio_link_t, zl_parent_node));
-	list_create(&zio->io_child_list, sizeof (zio_link_t),
-	    offsetof(zio_link_t, zl_child_node));
-
-	return (0);
-}
-
-static void
-zio_dest(void *arg, void *unused)
-{
-	zio_t *zio = arg;
-
-	mutex_destroy(&zio->io_lock);
-	cv_destroy(&zio->io_cv);
-	list_destroy(&zio->io_parent_list);
-	list_destroy(&zio->io_child_list);
-}
-
 void
 zio_init(void)
 {
@@ -137,8 +108,8 @@ zio_init(void)
 #ifdef _KERNEL
 	data_alloc_arena = zio_alloc_arena;
 #endif
-	zio_cache = kmem_cache_create("zio_cache", sizeof (zio_t), 0,
-	    zio_cons, zio_dest, NULL, NULL, NULL, KMC_KMEM);
+	zio_cache = kmem_cache_create("zio_cache",
+	    sizeof (zio_t), 0, NULL, NULL, NULL, NULL, NULL, KMC_KMEM);
 	zio_link_cache = kmem_cache_create("zio_link_cache",
 	    sizeof (zio_link_t), 0, NULL, NULL, NULL, NULL, NULL, KMC_KMEM);
 
@@ -540,6 +511,15 @@ zio_create(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
 	ASSERT(vd || stage == ZIO_STAGE_OPEN);
 
 	zio = kmem_cache_alloc(zio_cache, KM_PUSHPAGE);
+	bzero(zio, sizeof (zio_t));
+
+	mutex_init(&zio->io_lock, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&zio->io_cv, NULL, CV_DEFAULT, NULL);
+
+	list_create(&zio->io_parent_list, sizeof (zio_link_t),
+	    offsetof(zio_link_t, zl_parent_node));
+	list_create(&zio->io_child_list, sizeof (zio_link_t),
+	    offsetof(zio_link_t, zl_child_node));
 
 	if (vd != NULL)
 		zio->io_child_type = ZIO_CHILD_VDEV;
@@ -561,52 +541,21 @@ zio_create(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
 			zio->io_logical = zio;
 		if (zio->io_child_type > ZIO_CHILD_GANG && BP_IS_GANG(bp))
 			pipeline |= ZIO_GANG_STAGES;
-	} else {
-		zio->io_logical = NULL;
-		zio->io_bp = NULL;
-		bzero(&zio->io_bp_copy, sizeof (blkptr_t));
-		bzero(&zio->io_bp_orig, sizeof (blkptr_t));
 	}
 
 	zio->io_spa = spa;
 	zio->io_txg = txg;
-	zio->io_ready = NULL;
 	zio->io_done = done;
 	zio->io_private = private;
-	zio->io_prev_space_delta = 0;
 	zio->io_type = type;
 	zio->io_priority = priority;
 	zio->io_vd = vd;
-	zio->io_vsd = NULL;
-	zio->io_vsd_ops = NULL;
 	zio->io_offset = offset;
-	zio->io_deadline = 0;
 	zio->io_orig_data = zio->io_data = data;
 	zio->io_orig_size = zio->io_size = size;
 	zio->io_orig_flags = zio->io_flags = flags;
 	zio->io_orig_stage = zio->io_stage = stage;
 	zio->io_orig_pipeline = zio->io_pipeline = pipeline;
-	bzero(&zio->io_prop, sizeof (zio_prop_t));
-	zio->io_cmd = 0;
-	zio->io_reexecute = 0;
-	zio->io_bp_override = NULL;
-	zio->io_walk_link = NULL;
-	zio->io_transform_stack = NULL;
-	zio->io_delay = 0;
-	zio->io_error = 0;
-	zio->io_child_count = 0;
-	zio->io_parent_count = 0;
-	zio->io_stall = NULL;
-	zio->io_gang_leader = NULL;
-	zio->io_gang_tree = NULL;
-	zio->io_executor = NULL;
-	zio->io_waiter = NULL;
-	zio->io_cksum_report = NULL;
-	zio->io_ena = 0;
-	bzero(zio->io_child_error, sizeof (int) * ZIO_CHILD_TYPES);
-	bzero(zio->io_children,
-	    sizeof (uint64_t) * ZIO_CHILD_TYPES * ZIO_WAIT_TYPES);
-	bzero(&zio->io_bookmark, sizeof (zbookmark_t));
 
 	zio->io_state[ZIO_WAIT_READY] = (stage >= ZIO_STAGE_READY);
 	zio->io_state[ZIO_WAIT_DONE] = (stage >= ZIO_STAGE_DONE);
@@ -630,6 +579,10 @@ zio_create(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
 static void
 zio_destroy(zio_t *zio)
 {
+	list_destroy(&zio->io_parent_list);
+	list_destroy(&zio->io_child_list);
+	mutex_destroy(&zio->io_lock);
+	cv_destroy(&zio->io_cv);
 	kmem_cache_free(zio_cache, zio);
 }