--- zzzz-none-000/linux-3.10.107/fs/btrfs/ulist.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/btrfs/ulist.c	2021-02-04 17:41:59.000000000 +0000
@@ -5,8 +5,8 @@
  */
 
 #include <linux/slab.h>
-#include <linux/export.h>
 #include "ulist.h"
+#include "ctree.h"
 
 /*
  * ulist is a generic data structure to hold a collection of unique u64
@@ -14,10 +14,6 @@
  * enumerating it.
  * It is possible to store an auxiliary value along with the key.
  *
- * The implementation is preliminary and can probably be sped up
- * significantly. A first step would be to store the values in an rbtree
- * as soon as ULIST_SIZE is exceeded.
- *
  * A sample usage for ulists is the enumeration of directed graphs without
  * visiting a node twice. The pseudo-code could look like this:
  *
@@ -50,12 +46,10 @@
  */
 void ulist_init(struct ulist *ulist)
 {
-	ulist->nnodes = 0;
-	ulist->nodes = ulist->int_nodes;
-	ulist->nodes_alloced = ULIST_SIZE;
+	INIT_LIST_HEAD(&ulist->nodes);
 	ulist->root = RB_ROOT;
+	ulist->nnodes = 0;
 }
-EXPORT_SYMBOL(ulist_init);
 
 /**
  * ulist_fini - free up additionally allocated memory for the ulist
@@ -64,18 +58,17 @@
  * This is useful in cases where the base 'struct ulist' has been statically
  * allocated.
  */
-void ulist_fini(struct ulist *ulist)
+static void ulist_fini(struct ulist *ulist)
 {
-	/*
-	 * The first ULIST_SIZE elements are stored inline in struct ulist.
-	 * Only if more elements are alocated they need to be freed.
-	 */
-	if (ulist->nodes_alloced > ULIST_SIZE)
-		kfree(ulist->nodes);
-	ulist->nodes_alloced = 0;	/* in case ulist_fini is called twice */
+	struct ulist_node *node;
+	struct ulist_node *next;
+
+	list_for_each_entry_safe(node, next, &ulist->nodes, list) {
+		kfree(node);
+	}
 	ulist->root = RB_ROOT;
+	INIT_LIST_HEAD(&ulist->nodes);
 }
-EXPORT_SYMBOL(ulist_fini);
 
 /**
  * ulist_reinit - prepare a ulist for reuse
@@ -89,7 +82,6 @@
 	ulist_fini(ulist);
 	ulist_init(ulist);
 }
-EXPORT_SYMBOL(ulist_reinit);
 
 /**
  * ulist_alloc - dynamically allocate a ulist
@@ -108,7 +100,6 @@
 
 	return ulist;
 }
-EXPORT_SYMBOL(ulist_alloc);
 
 /**
  * ulist_free - free dynamically allocated ulist
@@ -123,7 +114,6 @@
 	ulist_fini(ulist);
 	kfree(ulist);
 }
-EXPORT_SYMBOL(ulist_free);
 
 static struct ulist_node *ulist_rbtree_search(struct ulist *ulist, u64 val)
 {
@@ -142,6 +132,15 @@
 	return NULL;
 }
 
+static void ulist_rbtree_erase(struct ulist *ulist, struct ulist_node *node)
+{
+	rb_erase(&node->rb_node, &ulist->root);
+	list_del(&node->list);
+	kfree(node);
+	BUG_ON(ulist->nnodes == 0);
+	ulist->nnodes--;
+}
+
 static int ulist_rbtree_insert(struct ulist *ulist, struct ulist_node *ins)
 {
 	struct rb_node **p = &ulist->root.rb_node;
@@ -192,63 +191,56 @@
 int ulist_add_merge(struct ulist *ulist, u64 val, u64 aux,
 		    u64 *old_aux, gfp_t gfp_mask)
 {
-	int ret = 0;
-	struct ulist_node *node = NULL;
+	int ret;
+	struct ulist_node *node;
+
 	node = ulist_rbtree_search(ulist, val);
 	if (node) {
 		if (old_aux)
 			*old_aux = node->aux;
 		return 0;
 	}
-
-	if (ulist->nnodes >= ulist->nodes_alloced) {
-		u64 new_alloced = ulist->nodes_alloced + 128;
-		struct ulist_node *new_nodes;
-		void *old = NULL;
-		int i;
-
-		for (i = 0; i < ulist->nnodes; i++)
-			rb_erase(&ulist->nodes[i].rb_node, &ulist->root);
-
-		/*
-		 * if nodes_alloced == ULIST_SIZE no memory has been allocated
-		 * yet, so pass NULL to krealloc
-		 */
-		if (ulist->nodes_alloced > ULIST_SIZE)
-			old = ulist->nodes;
-
-		new_nodes = krealloc(old, sizeof(*new_nodes) * new_alloced,
-				     gfp_mask);
-		if (!new_nodes)
-			return -ENOMEM;
-
-		if (!old)
-			memcpy(new_nodes, ulist->int_nodes,
-			       sizeof(ulist->int_nodes));
-
-		ulist->nodes = new_nodes;
-		ulist->nodes_alloced = new_alloced;
-
-		/*
-		 * krealloc actually uses memcpy, which does not copy rb_node
-		 * pointers, so we have to do it ourselves.  Otherwise we may
-		 * be bitten by crashes.
-		 */
-		for (i = 0; i < ulist->nnodes; i++) {
-			ret = ulist_rbtree_insert(ulist, &ulist->nodes[i]);
-			if (ret < 0)
-				return ret;
-		}
-	}
-	ulist->nodes[ulist->nnodes].val = val;
-	ulist->nodes[ulist->nnodes].aux = aux;
-	ret = ulist_rbtree_insert(ulist, &ulist->nodes[ulist->nnodes]);
-	BUG_ON(ret);
-	++ulist->nnodes;
+	node = kmalloc(sizeof(*node), gfp_mask);
+	if (!node)
+		return -ENOMEM;
+
+	node->val = val;
+	node->aux = aux;
+
+	ret = ulist_rbtree_insert(ulist, node);
+	ASSERT(!ret);
+	list_add_tail(&node->list, &ulist->nodes);
+	ulist->nnodes++;
 
 	return 1;
 }
-EXPORT_SYMBOL(ulist_add);
+
+/*
+ * ulist_del - delete one node from ulist
+ * @ulist:	ulist to remove node from
+ * @val:	value to delete
+ * @aux:	aux to delete
+ *
+ * The deletion will only be done when *BOTH* val and aux matches.
+ * Return 0 for successful delete.
+ * Return > 0 for not found.
+ */
+int ulist_del(struct ulist *ulist, u64 val, u64 aux)
+{
+	struct ulist_node *node;
+
+	node = ulist_rbtree_search(ulist, val);
+	/* Not found */
+	if (!node)
+		return 1;
+
+	if (node->aux != aux)
+		return 1;
+
+	/* Found and delete */
+	ulist_rbtree_erase(ulist, node);
+	return 0;
+}
 
 /**
  * ulist_next - iterate ulist
@@ -268,11 +260,17 @@
  */
 struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_iterator *uiter)
 {
-	if (ulist->nnodes == 0)
+	struct ulist_node *node;
+
+	if (list_empty(&ulist->nodes))
 		return NULL;
-	if (uiter->i < 0 || uiter->i >= ulist->nnodes)
+	if (uiter->cur_list && uiter->cur_list->next == &ulist->nodes)
 		return NULL;
-
-	return &ulist->nodes[uiter->i++];
+	if (uiter->cur_list) {
+		uiter->cur_list = uiter->cur_list->next;
+	} else {
+		uiter->cur_list = ulist->nodes.next;
+	}
+	node = list_entry(uiter->cur_list, struct ulist_node, list);
+	return node;
 }
-EXPORT_SYMBOL(ulist_next);