--- zzzz-none-000/linux-3.10.107/fs/btrfs/delayed-ref.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/btrfs/delayed-ref.c	2021-02-04 17:41:59.000000000 +0000
@@ -22,6 +22,7 @@
 #include "ctree.h"
 #include "delayed-ref.h"
 #include "transaction.h"
+#include "qgroup.h"
 
 struct kmem_cache *btrfs_delayed_ref_head_cachep;
 struct kmem_cache *btrfs_delayed_tree_ref_cachep;
@@ -84,73 +85,26 @@
 	return 0;
 }
 
-/*
- * entries in the rb tree are ordered by the byte number of the extent,
- * type of the delayed backrefs and content of delayed backrefs.
- */
-static int comp_entry(struct btrfs_delayed_ref_node *ref2,
-		      struct btrfs_delayed_ref_node *ref1,
-		      bool compare_seq)
-{
-	if (ref1->bytenr < ref2->bytenr)
-		return -1;
-	if (ref1->bytenr > ref2->bytenr)
-		return 1;
-	if (ref1->is_head && ref2->is_head)
-		return 0;
-	if (ref2->is_head)
-		return -1;
-	if (ref1->is_head)
-		return 1;
-	if (ref1->type < ref2->type)
-		return -1;
-	if (ref1->type > ref2->type)
-		return 1;
-	/* merging of sequenced refs is not allowed */
-	if (compare_seq) {
-		if (ref1->seq < ref2->seq)
-			return -1;
-		if (ref1->seq > ref2->seq)
-			return 1;
-	}
-	if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
-	    ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) {
-		return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2),
-				      btrfs_delayed_node_to_tree_ref(ref1),
-				      ref1->type);
-	} else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY ||
-		   ref1->type == BTRFS_SHARED_DATA_REF_KEY) {
-		return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2),
-				      btrfs_delayed_node_to_data_ref(ref1));
-	}
-	BUG();
-	return 0;
-}
-
-/*
- * insert a new ref into the rbtree.  This returns any existing refs
- * for the same (bytenr,parent) tuple, or NULL if the new node was properly
- * inserted.
- */
-static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root,
-						  struct rb_node *node)
+/* insert a new ref to head ref rbtree */
+static struct btrfs_delayed_ref_head *htree_insert(struct rb_root *root,
+						   struct rb_node *node)
 {
 	struct rb_node **p = &root->rb_node;
 	struct rb_node *parent_node = NULL;
-	struct btrfs_delayed_ref_node *entry;
-	struct btrfs_delayed_ref_node *ins;
-	int cmp;
+	struct btrfs_delayed_ref_head *entry;
+	struct btrfs_delayed_ref_head *ins;
+	u64 bytenr;
 
-	ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
+	ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
+	bytenr = ins->node.bytenr;
 	while (*p) {
 		parent_node = *p;
-		entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
-				 rb_node);
+		entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
+				 href_node);
 
-		cmp = comp_entry(entry, ins, 1);
-		if (cmp < 0)
+		if (bytenr < entry->node.bytenr)
 			p = &(*p)->rb_left;
-		else if (cmp > 0)
+		else if (bytenr > entry->node.bytenr)
 			p = &(*p)->rb_right;
 		else
 			return entry;
@@ -167,50 +121,33 @@
  * If return_bigger is given, the next bigger entry is returned if no exact
  * match is found.
  */
-static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root,
-				  u64 bytenr,
-				  struct btrfs_delayed_ref_node **last,
-				  int return_bigger)
+static struct btrfs_delayed_ref_head *
+find_ref_head(struct rb_root *root, u64 bytenr,
+	      int return_bigger)
 {
 	struct rb_node *n;
-	struct btrfs_delayed_ref_node *entry;
-	int cmp = 0;
+	struct btrfs_delayed_ref_head *entry;
 
-again:
 	n = root->rb_node;
 	entry = NULL;
 	while (n) {
-		entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node);
-		WARN_ON(!entry->in_tree);
-		if (last)
-			*last = entry;
-
-		if (bytenr < entry->bytenr)
-			cmp = -1;
-		else if (bytenr > entry->bytenr)
-			cmp = 1;
-		else if (!btrfs_delayed_ref_is_head(entry))
-			cmp = 1;
-		else
-			cmp = 0;
+		entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
 
-		if (cmp < 0)
+		if (bytenr < entry->node.bytenr)
 			n = n->rb_left;
-		else if (cmp > 0)
+		else if (bytenr > entry->node.bytenr)
 			n = n->rb_right;
 		else
 			return entry;
 	}
 	if (entry && return_bigger) {
-		if (cmp > 0) {
-			n = rb_next(&entry->rb_node);
+		if (bytenr > entry->node.bytenr) {
+			n = rb_next(&entry->href_node);
 			if (!n)
 				n = rb_first(root);
-			entry = rb_entry(n, struct btrfs_delayed_ref_node,
-					 rb_node);
-			bytenr = entry->bytenr;
-			return_bigger = 0;
-			goto again;
+			entry = rb_entry(n, struct btrfs_delayed_ref_head,
+					 href_node);
+			return entry;
 		}
 		return entry;
 	}
@@ -241,75 +178,90 @@
 	return 0;
 }
 
-static void inline drop_delayed_ref(struct btrfs_trans_handle *trans,
+static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
 				    struct btrfs_delayed_ref_root *delayed_refs,
+				    struct btrfs_delayed_ref_head *head,
 				    struct btrfs_delayed_ref_node *ref)
 {
-	rb_erase(&ref->rb_node, &delayed_refs->root);
+	if (btrfs_delayed_ref_is_head(ref)) {
+		head = btrfs_delayed_node_to_head(ref);
+		rb_erase(&head->href_node, &delayed_refs->href_root);
+	} else {
+		assert_spin_locked(&head->lock);
+		list_del(&ref->list);
+	}
 	ref->in_tree = 0;
 	btrfs_put_delayed_ref(ref);
-	delayed_refs->num_entries--;
+	atomic_dec(&delayed_refs->num_entries);
 	if (trans->delayed_ref_updates)
 		trans->delayed_ref_updates--;
 }
 
-static int merge_ref(struct btrfs_trans_handle *trans,
-		     struct btrfs_delayed_ref_root *delayed_refs,
-		     struct btrfs_delayed_ref_node *ref, u64 seq)
-{
-	struct rb_node *node;
-	int merged = 0;
-	int mod = 0;
-	int done = 0;
-
-	node = rb_prev(&ref->rb_node);
-	while (node) {
-		struct btrfs_delayed_ref_node *next;
-
-		next = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
-		node = rb_prev(node);
-		if (next->bytenr != ref->bytenr)
-			break;
+static bool merge_ref(struct btrfs_trans_handle *trans,
+		      struct btrfs_delayed_ref_root *delayed_refs,
+		      struct btrfs_delayed_ref_head *head,
+		      struct btrfs_delayed_ref_node *ref,
+		      u64 seq)
+{
+	struct btrfs_delayed_ref_node *next;
+	bool done = false;
+
+	next = list_first_entry(&head->ref_list, struct btrfs_delayed_ref_node,
+				list);
+	while (!done && &next->list != &head->ref_list) {
+		int mod;
+		struct btrfs_delayed_ref_node *next2;
+
+		next2 = list_next_entry(next, list);
+
+		if (next == ref)
+			goto next;
+
 		if (seq && next->seq >= seq)
-			break;
-		if (comp_entry(ref, next, 0))
-			continue;
+			goto next;
+
+		if (next->type != ref->type)
+			goto next;
+
+		if ((ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
+		     ref->type == BTRFS_SHARED_BLOCK_REF_KEY) &&
+		    comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref),
+				   btrfs_delayed_node_to_tree_ref(next),
+				   ref->type))
+			goto next;
+		if ((ref->type == BTRFS_EXTENT_DATA_REF_KEY ||
+		     ref->type == BTRFS_SHARED_DATA_REF_KEY) &&
+		    comp_data_refs(btrfs_delayed_node_to_data_ref(ref),
+				   btrfs_delayed_node_to_data_ref(next)))
+			goto next;
 
 		if (ref->action == next->action) {
 			mod = next->ref_mod;
 		} else {
 			if (ref->ref_mod < next->ref_mod) {
-				struct btrfs_delayed_ref_node *tmp;
-
-				tmp = ref;
-				ref = next;
-				next = tmp;
-				done = 1;
+				swap(ref, next);
+				done = true;
 			}
 			mod = -next->ref_mod;
 		}
 
-		merged++;
-		drop_delayed_ref(trans, delayed_refs, next);
+		drop_delayed_ref(trans, delayed_refs, head, next);
 		ref->ref_mod += mod;
 		if (ref->ref_mod == 0) {
-			drop_delayed_ref(trans, delayed_refs, ref);
-			break;
+			drop_delayed_ref(trans, delayed_refs, head, ref);
+			done = true;
 		} else {
 			/*
-			 * You can't have multiples of the same ref on a tree
-			 * block.
+			 * Can't have multiples of the same ref on a tree block.
 			 */
 			WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
 				ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
 		}
-
-		if (done)
-			break;
-		node = rb_prev(&ref->rb_node);
+next:
+		next = next2;
 	}
 
-	return merged;
+	return done;
 }
 
 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
@@ -317,9 +269,18 @@
 			      struct btrfs_delayed_ref_root *delayed_refs,
 			      struct btrfs_delayed_ref_head *head)
 {
-	struct rb_node *node;
+	struct btrfs_delayed_ref_node *ref;
 	u64 seq = 0;
 
+	assert_spin_locked(&head->lock);
+
+	if (list_empty(&head->ref_list))
+		return;
+
+	/* We don't have too many refs to merge for data. */
+	if (head->is_data)
+		return;
+
 	spin_lock(&fs_info->tree_mod_seq_lock);
 	if (!list_empty(&fs_info->tree_mod_seq_list)) {
 		struct seq_list *elem;
@@ -330,22 +291,22 @@
 	}
 	spin_unlock(&fs_info->tree_mod_seq_lock);
 
-	node = rb_prev(&head->node.rb_node);
-	while (node) {
-		struct btrfs_delayed_ref_node *ref;
-
-		ref = rb_entry(node, struct btrfs_delayed_ref_node,
-			       rb_node);
-		if (ref->bytenr != head->node.bytenr)
-			break;
-
-		/* We can't merge refs that are outside of our seq count */
+	ref = list_first_entry(&head->ref_list, struct btrfs_delayed_ref_node,
+			       list);
+	while (&ref->list != &head->ref_list) {
 		if (seq && ref->seq >= seq)
-			break;
-		if (merge_ref(trans, delayed_refs, ref, seq))
-			node = rb_prev(&head->node.rb_node);
-		else
-			node = rb_prev(node);
+			goto next;
+
+		if (merge_ref(trans, delayed_refs, head, ref, seq)) {
+			if (list_empty(&head->ref_list))
+				break;
+			ref = list_first_entry(&head->ref_list,
+					       struct btrfs_delayed_ref_node,
+					       list);
+			continue;
+		}
+next:
+		ref = list_next_entry(ref, list);
 	}
 }
 
@@ -373,112 +334,119 @@
 	return ret;
 }
 
-int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
-			   struct list_head *cluster, u64 start)
+struct btrfs_delayed_ref_head *
+btrfs_select_ref_head(struct btrfs_trans_handle *trans)
 {
-	int count = 0;
 	struct btrfs_delayed_ref_root *delayed_refs;
-	struct rb_node *node;
-	struct btrfs_delayed_ref_node *ref;
 	struct btrfs_delayed_ref_head *head;
+	u64 start;
+	bool loop = false;
 
 	delayed_refs = &trans->transaction->delayed_refs;
-	if (start == 0) {
-		node = rb_first(&delayed_refs->root);
-	} else {
-		ref = NULL;
-		find_ref_head(&delayed_refs->root, start + 1, &ref, 1);
-		if (ref) {
-			node = &ref->rb_node;
-		} else
-			node = rb_first(&delayed_refs->root);
-	}
+
 again:
-	while (node && count < 32) {
-		ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node);
-		if (btrfs_delayed_ref_is_head(ref)) {
-			head = btrfs_delayed_node_to_head(ref);
-			if (list_empty(&head->cluster)) {
-				list_add_tail(&head->cluster, cluster);
-				delayed_refs->run_delayed_start =
-					head->node.bytenr;
-				count++;
-
-				WARN_ON(delayed_refs->num_heads_ready == 0);
-				delayed_refs->num_heads_ready--;
-			} else if (count) {
-				/* the goal of the clustering is to find extents
-				 * that are likely to end up in the same extent
-				 * leaf on disk.  So, we don't want them spread
-				 * all over the tree.  Stop now if we've hit
-				 * a head that was already in use
-				 */
-				break;
-			}
-		}
-		node = rb_next(node);
-	}
-	if (count) {
-		return 0;
-	} else if (start) {
-		/*
-		 * we've gone to the end of the rbtree without finding any
-		 * clusters.  start from the beginning and try again
-		 */
+	start = delayed_refs->run_delayed_start;
+	head = find_ref_head(&delayed_refs->href_root, start, 1);
+	if (!head && !loop) {
+		delayed_refs->run_delayed_start = 0;
 		start = 0;
-		node = rb_first(&delayed_refs->root);
-		goto again;
+		loop = true;
+		head = find_ref_head(&delayed_refs->href_root, start, 1);
+		if (!head)
+			return NULL;
+	} else if (!head && loop) {
+		return NULL;
+	}
+
+	while (head->processing) {
+		struct rb_node *node;
+
+		node = rb_next(&head->href_node);
+		if (!node) {
+			if (loop)
+				return NULL;
+			delayed_refs->run_delayed_start = 0;
+			start = 0;
+			loop = true;
+			goto again;
+		}
+		head = rb_entry(node, struct btrfs_delayed_ref_head,
+				href_node);
 	}
-	return 1;
-}
-
-void btrfs_release_ref_cluster(struct list_head *cluster)
-{
-	struct list_head *pos, *q;
 
-	list_for_each_safe(pos, q, cluster)
-		list_del_init(pos);
+	head->processing = 1;
+	WARN_ON(delayed_refs->num_heads_ready == 0);
+	delayed_refs->num_heads_ready--;
+	delayed_refs->run_delayed_start = head->node.bytenr +
+		head->node.num_bytes;
+	return head;
 }
 
 /*
- * helper function to update an extent delayed ref in the
- * rbtree.  existing and update must both have the same
- * bytenr and parent
+ * Helper to insert the ref_node to the tail or merge with tail.
  *
- * This may free existing if the update cancels out whatever
- * operation it was doing.
+ * Return 0 for insert.
+ * Return >0 for merge.
  */
-static noinline void
-update_existing_ref(struct btrfs_trans_handle *trans,
-		    struct btrfs_delayed_ref_root *delayed_refs,
-		    struct btrfs_delayed_ref_node *existing,
-		    struct btrfs_delayed_ref_node *update)
+static int
+add_delayed_ref_tail_merge(struct btrfs_trans_handle *trans,
+			   struct btrfs_delayed_ref_root *root,
+			   struct btrfs_delayed_ref_head *href,
+			   struct btrfs_delayed_ref_node *ref)
 {
-	if (update->action != existing->action) {
-		/*
-		 * this is effectively undoing either an add or a
-		 * drop.  We decrement the ref_mod, and if it goes
-		 * down to zero we just delete the entry without
-		 * every changing the extent allocation tree.
-		 */
-		existing->ref_mod--;
-		if (existing->ref_mod == 0)
-			drop_delayed_ref(trans, delayed_refs, existing);
-		else
-			WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
-				existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
+	struct btrfs_delayed_ref_node *exist;
+	int mod;
+	int ret = 0;
+
+	spin_lock(&href->lock);
+	/* Check whether we can merge the tail node with ref */
+	if (list_empty(&href->ref_list))
+		goto add_tail;
+	exist = list_entry(href->ref_list.prev, struct btrfs_delayed_ref_node,
+			   list);
+	/* No need to compare bytenr nor is_head */
+	if (exist->type != ref->type || exist->seq != ref->seq)
+		goto add_tail;
+
+	if ((exist->type == BTRFS_TREE_BLOCK_REF_KEY ||
+	     exist->type == BTRFS_SHARED_BLOCK_REF_KEY) &&
+	    comp_tree_refs(btrfs_delayed_node_to_tree_ref(exist),
+			   btrfs_delayed_node_to_tree_ref(ref),
+			   ref->type))
+		goto add_tail;
+	if ((exist->type == BTRFS_EXTENT_DATA_REF_KEY ||
+	     exist->type == BTRFS_SHARED_DATA_REF_KEY) &&
+	    comp_data_refs(btrfs_delayed_node_to_data_ref(exist),
+			   btrfs_delayed_node_to_data_ref(ref)))
+		goto add_tail;
+
+	/* Now we are sure we can merge */
+	ret = 1;
+	if (exist->action == ref->action) {
+		mod = ref->ref_mod;
 	} else {
-		WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY ||
-			existing->type == BTRFS_SHARED_BLOCK_REF_KEY);
-		/*
-		 * the action on the existing ref matches
-		 * the action on the ref we're trying to add.
-		 * Bump the ref_mod by one so the backref that
-		 * is eventually added/removed has the correct
-		 * reference count
-		 */
-		existing->ref_mod += update->ref_mod;
+		/* Need to change action */
+		if (exist->ref_mod < ref->ref_mod) {
+			exist->action = ref->action;
+			mod = -exist->ref_mod;
+			exist->ref_mod = ref->ref_mod;
+		} else
+			mod = -ref->ref_mod;
 	}
+	exist->ref_mod += mod;
+
+	/* remove existing tail if its ref_mod is zero */
+	if (exist->ref_mod == 0)
+		drop_delayed_ref(trans, root, href, exist);
+	spin_unlock(&href->lock);
+	return ret;
+
+add_tail:
+	list_add_tail(&ref->list, &href->ref_list);
+	atomic_inc(&root->num_entries);
+	trans->delayed_ref_updates++;
+	spin_unlock(&href->lock);
+	return ret;
 }
 
 /*
@@ -486,16 +454,19 @@
  * existing and update must have the same bytenr
  */
 static noinline void
-update_existing_head_ref(struct btrfs_delayed_ref_node *existing,
+update_existing_head_ref(struct btrfs_delayed_ref_root *delayed_refs,
+			 struct btrfs_delayed_ref_node *existing,
 			 struct btrfs_delayed_ref_node *update)
 {
 	struct btrfs_delayed_ref_head *existing_ref;
 	struct btrfs_delayed_ref_head *ref;
+	int old_ref_mod;
 
 	existing_ref = btrfs_delayed_node_to_head(existing);
 	ref = btrfs_delayed_node_to_head(update);
 	BUG_ON(existing_ref->is_data != ref->is_data);
 
+	spin_lock(&existing_ref->lock);
 	if (ref->must_insert_reserved) {
 		/* if the extent was freed and then
 		 * reallocated before the delayed ref
@@ -533,9 +504,25 @@
 		}
 	}
 	/*
-	 * update the reference mod on the head to reflect this new operation
+	 * update the reference mod on the head to reflect this new operation,
+	 * only need the lock for this case cause we could be processing it
+	 * currently, for refs we just added we know we're a-ok.
 	 */
+	old_ref_mod = existing_ref->total_ref_mod;
 	existing->ref_mod += update->ref_mod;
+	existing_ref->total_ref_mod += update->ref_mod;
+
+	/*
+	 * If we are going to from a positive ref mod to a negative or vice
+	 * versa we need to make sure to adjust pending_csums accordingly.
+	 */
+	if (existing_ref->is_data) {
+		if (existing_ref->total_ref_mod >= 0 && old_ref_mod < 0)
+			delayed_refs->pending_csums -= existing->num_bytes;
+		if (existing_ref->total_ref_mod < 0 && old_ref_mod >= 0)
+			delayed_refs->pending_csums += existing->num_bytes;
+	}
+	spin_unlock(&existing_ref->lock);
 }
 
 /*
@@ -543,18 +530,24 @@
  * this does all the dirty work in terms of maintaining the correct
  * overall modification count.
  */
-static noinline void add_delayed_ref_head(struct btrfs_fs_info *fs_info,
-					struct btrfs_trans_handle *trans,
-					struct btrfs_delayed_ref_node *ref,
-					u64 bytenr, u64 num_bytes,
-					int action, int is_data)
+static noinline struct btrfs_delayed_ref_head *
+add_delayed_ref_head(struct btrfs_fs_info *fs_info,
+		     struct btrfs_trans_handle *trans,
+		     struct btrfs_delayed_ref_node *ref,
+		     struct btrfs_qgroup_extent_record *qrecord,
+		     u64 bytenr, u64 num_bytes, u64 ref_root, u64 reserved,
+		     int action, int is_data)
 {
-	struct btrfs_delayed_ref_node *existing;
+	struct btrfs_delayed_ref_head *existing;
 	struct btrfs_delayed_ref_head *head_ref = NULL;
 	struct btrfs_delayed_ref_root *delayed_refs;
+	struct btrfs_qgroup_extent_record *qexisting;
 	int count_mod = 1;
 	int must_insert_reserved = 0;
 
+	/* If reserved is provided, it must be a data extent. */
+	BUG_ON(!is_data && reserved);
+
 	/*
 	 * the head node stores the sum of all the mods, so dropping a ref
 	 * should drop the sum in the head node by one.
@@ -596,47 +589,78 @@
 	head_ref = btrfs_delayed_node_to_head(ref);
 	head_ref->must_insert_reserved = must_insert_reserved;
 	head_ref->is_data = is_data;
+	INIT_LIST_HEAD(&head_ref->ref_list);
+	head_ref->processing = 0;
+	head_ref->total_ref_mod = count_mod;
+	head_ref->qgroup_reserved = 0;
+	head_ref->qgroup_ref_root = 0;
+
+	/* Record qgroup extent info if provided */
+	if (qrecord) {
+		if (ref_root && reserved) {
+			head_ref->qgroup_ref_root = ref_root;
+			head_ref->qgroup_reserved = reserved;
+		}
 
-	INIT_LIST_HEAD(&head_ref->cluster);
-	mutex_init(&head_ref->mutex);
+		qrecord->bytenr = bytenr;
+		qrecord->num_bytes = num_bytes;
+		qrecord->old_roots = NULL;
 
-	trace_btrfs_delayed_ref_head(ref, head_ref, action);
+		qexisting = btrfs_qgroup_insert_dirty_extent(delayed_refs,
+							     qrecord);
+		if (qexisting)
+			kfree(qrecord);
+	}
+
+	spin_lock_init(&head_ref->lock);
+	mutex_init(&head_ref->mutex);
 
-	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
+	trace_add_delayed_ref_head(ref, head_ref, action);
 
+	existing = htree_insert(&delayed_refs->href_root,
+				&head_ref->href_node);
 	if (existing) {
-		update_existing_head_ref(existing, ref);
+		WARN_ON(ref_root && reserved && existing->qgroup_ref_root
+			&& existing->qgroup_reserved);
+		update_existing_head_ref(delayed_refs, &existing->node, ref);
 		/*
 		 * we've updated the existing ref, free the newly
 		 * allocated ref
 		 */
 		kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
+		head_ref = existing;
 	} else {
+		if (is_data && count_mod < 0)
+			delayed_refs->pending_csums += num_bytes;
 		delayed_refs->num_heads++;
 		delayed_refs->num_heads_ready++;
-		delayed_refs->num_entries++;
+		atomic_inc(&delayed_refs->num_entries);
 		trans->delayed_ref_updates++;
 	}
+	return head_ref;
 }
 
 /*
  * helper to insert a delayed tree ref into the rbtree.
  */
-static noinline void add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
-					 struct btrfs_trans_handle *trans,
-					 struct btrfs_delayed_ref_node *ref,
-					 u64 bytenr, u64 num_bytes, u64 parent,
-					 u64 ref_root, int level, int action,
-					 int for_cow)
+static noinline void
+add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
+		     struct btrfs_trans_handle *trans,
+		     struct btrfs_delayed_ref_head *head_ref,
+		     struct btrfs_delayed_ref_node *ref, u64 bytenr,
+		     u64 num_bytes, u64 parent, u64 ref_root, int level,
+		     int action)
 {
-	struct btrfs_delayed_ref_node *existing;
 	struct btrfs_delayed_tree_ref *full_ref;
 	struct btrfs_delayed_ref_root *delayed_refs;
 	u64 seq = 0;
+	int ret;
 
 	if (action == BTRFS_ADD_DELAYED_EXTENT)
 		action = BTRFS_ADD_DELAYED_REF;
 
+	if (is_fstree(ref_root))
+		seq = atomic64_read(&fs_info->tree_mod_seq);
 	delayed_refs = &trans->transaction->delayed_refs;
 
 	/* first set the basic ref node struct up */
@@ -647,9 +671,6 @@
 	ref->action = action;
 	ref->is_head = 0;
 	ref->in_tree = 1;
-
-	if (need_ref_seq(for_cow, ref_root))
-		seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 	ref->seq = seq;
 
 	full_ref = btrfs_delayed_node_to_tree_ref(ref);
@@ -661,43 +682,42 @@
 		ref->type = BTRFS_TREE_BLOCK_REF_KEY;
 	full_ref->level = level;
 
-	trace_btrfs_delayed_tree_ref(ref, full_ref, action);
+	trace_add_delayed_tree_ref(ref, full_ref, action);
 
-	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
+	ret = add_delayed_ref_tail_merge(trans, delayed_refs, head_ref, ref);
 
-	if (existing) {
-		update_existing_ref(trans, delayed_refs, existing, ref);
-		/*
-		 * we've updated the existing ref, free the newly
-		 * allocated ref
-		 */
+	/*
+	 * XXX: memory should be freed at the same level allocated.
+	 * But bad practice is anywhere... Follow it now. Need cleanup.
+	 */
+	if (ret > 0)
 		kmem_cache_free(btrfs_delayed_tree_ref_cachep, full_ref);
-	} else {
-		delayed_refs->num_entries++;
-		trans->delayed_ref_updates++;
-	}
 }
 
 /*
  * helper to insert a delayed data ref into the rbtree.
  */
-static noinline void add_delayed_data_ref(struct btrfs_fs_info *fs_info,
-					 struct btrfs_trans_handle *trans,
-					 struct btrfs_delayed_ref_node *ref,
-					 u64 bytenr, u64 num_bytes, u64 parent,
-					 u64 ref_root, u64 owner, u64 offset,
-					 int action, int for_cow)
+static noinline void
+add_delayed_data_ref(struct btrfs_fs_info *fs_info,
+		     struct btrfs_trans_handle *trans,
+		     struct btrfs_delayed_ref_head *head_ref,
+		     struct btrfs_delayed_ref_node *ref, u64 bytenr,
+		     u64 num_bytes, u64 parent, u64 ref_root, u64 owner,
+		     u64 offset, int action)
 {
-	struct btrfs_delayed_ref_node *existing;
 	struct btrfs_delayed_data_ref *full_ref;
 	struct btrfs_delayed_ref_root *delayed_refs;
 	u64 seq = 0;
+	int ret;
 
 	if (action == BTRFS_ADD_DELAYED_EXTENT)
 		action = BTRFS_ADD_DELAYED_REF;
 
 	delayed_refs = &trans->transaction->delayed_refs;
 
+	if (is_fstree(ref_root))
+		seq = atomic64_read(&fs_info->tree_mod_seq);
+
 	/* first set the basic ref node struct up */
 	atomic_set(&ref->refs, 1);
 	ref->bytenr = bytenr;
@@ -706,9 +726,6 @@
 	ref->action = action;
 	ref->is_head = 0;
 	ref->in_tree = 1;
-
-	if (need_ref_seq(for_cow, ref_root))
-		seq = btrfs_get_tree_mod_seq(fs_info, &trans->delayed_ref_elem);
 	ref->seq = seq;
 
 	full_ref = btrfs_delayed_node_to_data_ref(ref);
@@ -722,21 +739,12 @@
 	full_ref->objectid = owner;
 	full_ref->offset = offset;
 
-	trace_btrfs_delayed_data_ref(ref, full_ref, action);
+	trace_add_delayed_data_ref(ref, full_ref, action);
 
-	existing = tree_insert(&delayed_refs->root, &ref->rb_node);
+	ret = add_delayed_ref_tail_merge(trans, delayed_refs, head_ref, ref);
 
-	if (existing) {
-		update_existing_ref(trans, delayed_refs, existing, ref);
-		/*
-		 * we've updated the existing ref, free the newly
-		 * allocated ref
-		 */
+	if (ret > 0)
 		kmem_cache_free(btrfs_delayed_data_ref_cachep, full_ref);
-	} else {
-		delayed_refs->num_entries++;
-		trans->delayed_ref_updates++;
-	}
 }
 
 /*
@@ -748,12 +756,12 @@
 			       struct btrfs_trans_handle *trans,
 			       u64 bytenr, u64 num_bytes, u64 parent,
 			       u64 ref_root,  int level, int action,
-			       struct btrfs_delayed_extent_op *extent_op,
-			       int for_cow)
+			       struct btrfs_delayed_extent_op *extent_op)
 {
 	struct btrfs_delayed_tree_ref *ref;
 	struct btrfs_delayed_ref_head *head_ref;
 	struct btrfs_delayed_ref_root *delayed_refs;
+	struct btrfs_qgroup_extent_record *record = NULL;
 
 	BUG_ON(extent_op && extent_op->is_data);
 	ref = kmem_cache_alloc(btrfs_delayed_tree_ref_cachep, GFP_NOFS);
@@ -761,9 +769,13 @@
 		return -ENOMEM;
 
 	head_ref = kmem_cache_alloc(btrfs_delayed_ref_head_cachep, GFP_NOFS);
-	if (!head_ref) {
-		kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
-		return -ENOMEM;
+	if (!head_ref)
+		goto free_ref;
+
+	if (fs_info->quota_enabled && is_fstree(ref_root)) {
+		record = kmalloc(sizeof(*record), GFP_NOFS);
+		if (!record)
+			goto free_head_ref;
 	}
 
 	head_ref->extent_op = extent_op;
@@ -775,17 +787,21 @@
 	 * insert both the head node and the new ref without dropping
 	 * the spin lock
 	 */
-	add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
-				   num_bytes, action, 0);
+	head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node, record,
+					bytenr, num_bytes, 0, 0, action, 0);
 
-	add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
-				   num_bytes, parent, ref_root, level, action,
-				   for_cow);
+	add_delayed_tree_ref(fs_info, trans, head_ref, &ref->node, bytenr,
+			     num_bytes, parent, ref_root, level, action);
 	spin_unlock(&delayed_refs->lock);
-	if (need_ref_seq(for_cow, ref_root))
-		btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 
 	return 0;
+
+free_head_ref:
+	kmem_cache_free(btrfs_delayed_ref_head_cachep, head_ref);
+free_ref:
+	kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
+
+	return -ENOMEM;
 }
 
 /*
@@ -795,13 +811,13 @@
 			       struct btrfs_trans_handle *trans,
 			       u64 bytenr, u64 num_bytes,
 			       u64 parent, u64 ref_root,
-			       u64 owner, u64 offset, int action,
-			       struct btrfs_delayed_extent_op *extent_op,
-			       int for_cow)
+			       u64 owner, u64 offset, u64 reserved, int action,
+			       struct btrfs_delayed_extent_op *extent_op)
 {
 	struct btrfs_delayed_data_ref *ref;
 	struct btrfs_delayed_ref_head *head_ref;
 	struct btrfs_delayed_ref_root *delayed_refs;
+	struct btrfs_qgroup_extent_record *record = NULL;
 
 	BUG_ON(extent_op && !extent_op->is_data);
 	ref = kmem_cache_alloc(btrfs_delayed_data_ref_cachep, GFP_NOFS);
@@ -814,6 +830,16 @@
 		return -ENOMEM;
 	}
 
+	if (fs_info->quota_enabled && is_fstree(ref_root)) {
+		record = kmalloc(sizeof(*record), GFP_NOFS);
+		if (!record) {
+			kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
+			kmem_cache_free(btrfs_delayed_ref_head_cachep,
+					head_ref);
+			return -ENOMEM;
+		}
+	}
+
 	head_ref->extent_op = extent_op;
 
 	delayed_refs = &trans->transaction->delayed_refs;
@@ -823,19 +849,45 @@
 	 * insert both the head node and the new ref without dropping
 	 * the spin lock
 	 */
-	add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
-				   num_bytes, action, 1);
+	head_ref = add_delayed_ref_head(fs_info, trans, &head_ref->node, record,
+					bytenr, num_bytes, ref_root, reserved,
+					action, 1);
 
-	add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
+	add_delayed_data_ref(fs_info, trans, head_ref, &ref->node, bytenr,
 				   num_bytes, parent, ref_root, owner, offset,
-				   action, for_cow);
+				   action);
 	spin_unlock(&delayed_refs->lock);
-	if (need_ref_seq(for_cow, ref_root))
-		btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
 
 	return 0;
 }
 
+int btrfs_add_delayed_qgroup_reserve(struct btrfs_fs_info *fs_info,
+				     struct btrfs_trans_handle *trans,
+				     u64 ref_root, u64 bytenr, u64 num_bytes)
+{
+	struct btrfs_delayed_ref_root *delayed_refs;
+	struct btrfs_delayed_ref_head *ref_head;
+	int ret = 0;
+
+	if (!fs_info->quota_enabled || !is_fstree(ref_root))
+		return 0;
+
+	delayed_refs = &trans->transaction->delayed_refs;
+
+	spin_lock(&delayed_refs->lock);
+	ref_head = find_ref_head(&delayed_refs->href_root, bytenr, 0);
+	if (!ref_head) {
+		ret = -ENOENT;
+		goto out;
+	}
+	WARN_ON(ref_head->qgroup_reserved || ref_head->qgroup_ref_root);
+	ref_head->qgroup_ref_root = ref_root;
+	ref_head->qgroup_reserved = num_bytes;
+out:
+	spin_unlock(&delayed_refs->lock);
+	return ret;
+}
+
 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 				struct btrfs_trans_handle *trans,
 				u64 bytenr, u64 num_bytes,
@@ -853,9 +905,9 @@
 	delayed_refs = &trans->transaction->delayed_refs;
 	spin_lock(&delayed_refs->lock);
 
-	add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr,
-				   num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
-				   extent_op->is_data);
+	add_delayed_ref_head(fs_info, trans, &head_ref->node, NULL, bytenr,
+			     num_bytes, 0, 0, BTRFS_UPDATE_DELAYED_HEAD,
+			     extent_op->is_data);
 
 	spin_unlock(&delayed_refs->lock);
 	return 0;
@@ -869,14 +921,10 @@
 struct btrfs_delayed_ref_head *
 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 {
-	struct btrfs_delayed_ref_node *ref;
 	struct btrfs_delayed_ref_root *delayed_refs;
 
 	delayed_refs = &trans->transaction->delayed_refs;
-	ref = find_ref_head(&delayed_refs->root, bytenr, NULL, 0);
-	if (ref)
-		return btrfs_delayed_node_to_head(ref);
-	return NULL;
+	return find_ref_head(&delayed_refs->href_root, bytenr, 0);
 }
 
 void btrfs_delayed_ref_exit(void)