--- zzzz-none-000/linux-3.10.107/fs/btrfs/extent_map.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/btrfs/extent_map.c	2021-02-04 17:41:59.000000000 +0000
@@ -51,7 +51,7 @@
 	em = kmem_cache_zalloc(extent_map_cache, GFP_NOFS);
 	if (!em)
 		return NULL;
-	em->in_tree = 0;
+	RB_CLEAR_NODE(&em->rb_node);
 	em->flags = 0;
 	em->compress_type = BTRFS_COMPRESS_NONE;
 	em->generation = 0;
@@ -73,38 +73,64 @@
 		return;
 	WARN_ON(atomic_read(&em->refs) == 0);
 	if (atomic_dec_and_test(&em->refs)) {
-		WARN_ON(em->in_tree);
+		WARN_ON(extent_map_in_tree(em));
 		WARN_ON(!list_empty(&em->list));
+		if (test_bit(EXTENT_FLAG_FS_MAPPING, &em->flags))
+			kfree(em->bdev);
 		kmem_cache_free(extent_map_cache, em);
 	}
 }
 
-static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
-				   struct rb_node *node)
+/* simple helper to do math around the end of an extent, handling wrap */
+static u64 range_end(u64 start, u64 len)
+{
+	if (start + len < start)
+		return (u64)-1;
+	return start + len;
+}
+
+static int tree_insert(struct rb_root *root, struct extent_map *em)
 {
 	struct rb_node **p = &root->rb_node;
 	struct rb_node *parent = NULL;
-	struct extent_map *entry;
+	struct extent_map *entry = NULL;
+	struct rb_node *orig_parent = NULL;
+	u64 end = range_end(em->start, em->len);
 
 	while (*p) {
 		parent = *p;
 		entry = rb_entry(parent, struct extent_map, rb_node);
 
-		WARN_ON(!entry->in_tree);
-
-		if (offset < entry->start)
+		if (em->start < entry->start)
 			p = &(*p)->rb_left;
-		else if (offset >= extent_map_end(entry))
+		else if (em->start >= extent_map_end(entry))
 			p = &(*p)->rb_right;
 		else
-			return parent;
+			return -EEXIST;
 	}
 
-	entry = rb_entry(node, struct extent_map, rb_node);
-	entry->in_tree = 1;
-	rb_link_node(node, parent, p);
-	rb_insert_color(node, root);
-	return NULL;
+	orig_parent = parent;
+	while (parent && em->start >= extent_map_end(entry)) {
+		parent = rb_next(parent);
+		entry = rb_entry(parent, struct extent_map, rb_node);
+	}
+	if (parent)
+		if (end > entry->start && em->start < extent_map_end(entry))
+			return -EEXIST;
+
+	parent = orig_parent;
+	entry = rb_entry(parent, struct extent_map, rb_node);
+	while (parent && em->start < entry->start) {
+		parent = rb_prev(parent);
+		entry = rb_entry(parent, struct extent_map, rb_node);
+	}
+	if (parent)
+		if (end > entry->start && em->start < extent_map_end(entry))
+			return -EEXIST;
+
+	rb_link_node(&em->rb_node, orig_parent, p);
+	rb_insert_color(&em->rb_node, root);
+	return 0;
 }
 
 /*
@@ -126,8 +152,6 @@
 		prev = n;
 		prev_entry = entry;
 
-		WARN_ON(!entry->in_tree);
-
 		if (offset < entry->start)
 			n = n->rb_left;
 		else if (offset >= extent_map_end(entry))
@@ -213,12 +237,12 @@
 			em->len += merge->len;
 			em->block_len += merge->block_len;
 			em->block_start = merge->block_start;
-			merge->in_tree = 0;
 			em->mod_len = (em->mod_len + em->mod_start) - merge->mod_start;
 			em->mod_start = merge->mod_start;
 			em->generation = max(em->generation, merge->generation);
 
 			rb_erase(&merge->rb_node, &tree->map);
+			RB_CLEAR_NODE(&merge->rb_node);
 			free_extent_map(merge);
 		}
 	}
@@ -228,9 +252,9 @@
 		merge = rb_entry(rb, struct extent_map, rb_node);
 	if (rb && mergable_maps(em, merge)) {
 		em->len += merge->len;
-		em->block_len += merge->len;
+		em->block_len += merge->block_len;
 		rb_erase(&merge->rb_node, &tree->map);
-		merge->in_tree = 0;
+		RB_CLEAR_NODE(&merge->rb_node);
 		em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;
 		em->generation = max(em->generation, merge->generation);
 		free_extent_map(merge);
@@ -290,7 +314,21 @@
 void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
 {
 	clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
-	if (em->in_tree)
+	if (extent_map_in_tree(em))
+		try_merge_map(tree, em);
+}
+
+static inline void setup_extent_mapping(struct extent_map_tree *tree,
+					struct extent_map *em,
+					int modified)
+{
+	atomic_inc(&em->refs);
+	em->mod_start = em->start;
+	em->mod_len = em->len;
+
+	if (modified)
+		list_move(&em->list, &tree->modified_extents);
+	else
 		try_merge_map(tree, em);
 }
 
@@ -308,41 +346,16 @@
 		       struct extent_map *em, int modified)
 {
 	int ret = 0;
-	struct rb_node *rb;
-	struct extent_map *exist;
 
-	exist = lookup_extent_mapping(tree, em->start, em->len);
-	if (exist) {
-		free_extent_map(exist);
-		ret = -EEXIST;
-		goto out;
-	}
-	rb = tree_insert(&tree->map, em->start, &em->rb_node);
-	if (rb) {
-		ret = -EEXIST;
+	ret = tree_insert(&tree->map, em);
+	if (ret)
 		goto out;
-	}
-	atomic_inc(&em->refs);
 
-	em->mod_start = em->start;
-	em->mod_len = em->len;
-
-	if (modified)
-		list_move(&em->list, &tree->modified_extents);
-	else
-		try_merge_map(tree, em);
+	setup_extent_mapping(tree, em, modified);
 out:
 	return ret;
 }
 
-/* simple helper to do math around the end of an extent, handling wrap */
-static u64 range_end(u64 start, u64 len)
-{
-	if (start + len < start)
-		return (u64)-1;
-	return start + len;
-}
-
 static struct extent_map *
 __lookup_extent_mapping(struct extent_map_tree *tree,
 			u64 start, u64 len, int strict)
@@ -422,6 +435,21 @@
 	rb_erase(&em->rb_node, &tree->map);
 	if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))
 		list_del_init(&em->list);
-	em->in_tree = 0;
+	RB_CLEAR_NODE(&em->rb_node);
 	return ret;
 }
+
+void replace_extent_mapping(struct extent_map_tree *tree,
+			    struct extent_map *cur,
+			    struct extent_map *new,
+			    int modified)
+{
+	WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags));
+	ASSERT(extent_map_in_tree(cur));
+	if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags))
+		list_del_init(&cur->list);
+	rb_replace_node(&cur->rb_node, &new->rb_node, &tree->map);
+	RB_CLEAR_NODE(&cur->rb_node);
+
+	setup_extent_mapping(tree, new, modified);
+}