// SPDX-License-Identifier: GPL-2.0

  /*
   * Copyright (C) 2011 STRATO.  All rights reserved.

   */
  
  #include <linux/sched.h>
  #include <linux/pagemap.h>
  #include <linux/writeback.h>
  #include <linux/blkdev.h>
  #include <linux/rbtree.h>
  #include <linux/slab.h>
  #include <linux/workqueue.h>

  #include <linux/btrfs.h>

  
  #include "ctree.h"
  #include "transaction.h"
  #include "disk-io.h"
  #include "locking.h"
  #include "ulist.h"

  #include "backref.h"

  #include "extent_io.h"

  #include "qgroup.h"

  #include "block-group.h"

  #include "sysfs.h"

  /* TODO XXX FIXME
   *  - subvol delete -> delete when ref goes to 0? delete limits also?
   *  - reorganize keys
   *  - compressed
   *  - sync

   *  - copy also limits on subvol creation
   *  - limit

   *  - caches for ulists

   *  - performance benchmarks
   *  - check all ioctl parameters
   */

  /*
   * Helpers to access qgroup reservation
   *
   * Callers should ensure the lock context and type are valid
   */
  
  static u64 qgroup_rsv_total(const struct btrfs_qgroup *qgroup)
  {
  	u64 ret = 0;
  	int i;
  
  	for (i = 0; i < BTRFS_QGROUP_RSV_LAST; i++)
  		ret += qgroup->rsv.values[i];
  
  	return ret;
  }
  
  #ifdef CONFIG_BTRFS_DEBUG
  static const char *qgroup_rsv_type_str(enum btrfs_qgroup_rsv_type type)
  {
  	if (type == BTRFS_QGROUP_RSV_DATA)
  		return "data";

  	if (type == BTRFS_QGROUP_RSV_META_PERTRANS)
  		return "meta_pertrans";
  	if (type == BTRFS_QGROUP_RSV_META_PREALLOC)
  		return "meta_prealloc";

  	return NULL;
  }
  #endif

  static void qgroup_rsv_add(struct btrfs_fs_info *fs_info,
  			   struct btrfs_qgroup *qgroup, u64 num_bytes,

  			   enum btrfs_qgroup_rsv_type type)
  {

  	trace_qgroup_update_reserve(fs_info, qgroup, num_bytes, type);

  	qgroup->rsv.values[type] += num_bytes;
  }

  static void qgroup_rsv_release(struct btrfs_fs_info *fs_info,
  			       struct btrfs_qgroup *qgroup, u64 num_bytes,

  			       enum btrfs_qgroup_rsv_type type)
  {

  	trace_qgroup_update_reserve(fs_info, qgroup, -(s64)num_bytes, type);

  	if (qgroup->rsv.values[type] >= num_bytes) {
  		qgroup->rsv.values[type] -= num_bytes;
  		return;
  	}
  #ifdef CONFIG_BTRFS_DEBUG
  	WARN_RATELIMIT(1,
  		"qgroup %llu %s reserved space underflow, have %llu to free %llu",
  		qgroup->qgroupid, qgroup_rsv_type_str(type),
  		qgroup->rsv.values[type], num_bytes);
  #endif
  	qgroup->rsv.values[type] = 0;
  }

  static void qgroup_rsv_add_by_qgroup(struct btrfs_fs_info *fs_info,
  				     struct btrfs_qgroup *dest,
  				     struct btrfs_qgroup *src)

  {
  	int i;
  
  	for (i = 0; i < BTRFS_QGROUP_RSV_LAST; i++)

  		qgroup_rsv_add(fs_info, dest, src->rsv.values[i], i);

  }

  static void qgroup_rsv_release_by_qgroup(struct btrfs_fs_info *fs_info,
  					 struct btrfs_qgroup *dest,

  					  struct btrfs_qgroup *src)
  {
  	int i;
  
  	for (i = 0; i < BTRFS_QGROUP_RSV_LAST; i++)

  		qgroup_rsv_release(fs_info, dest, src->rsv.values[i], i);

  }

  static void btrfs_qgroup_update_old_refcnt(struct btrfs_qgroup *qg, u64 seq,
  					   int mod)
  {
  	if (qg->old_refcnt < seq)
  		qg->old_refcnt = seq;
  	qg->old_refcnt += mod;
  }
  
  static void btrfs_qgroup_update_new_refcnt(struct btrfs_qgroup *qg, u64 seq,
  					   int mod)
  {
  	if (qg->new_refcnt < seq)
  		qg->new_refcnt = seq;
  	qg->new_refcnt += mod;
  }
  
  static inline u64 btrfs_qgroup_get_old_refcnt(struct btrfs_qgroup *qg, u64 seq)
  {
  	if (qg->old_refcnt < seq)
  		return 0;
  	return qg->old_refcnt - seq;
  }
  
  static inline u64 btrfs_qgroup_get_new_refcnt(struct btrfs_qgroup *qg, u64 seq)
  {
  	if (qg->new_refcnt < seq)
  		return 0;
  	return qg->new_refcnt - seq;
  }

  /*
   * glue structure to represent the relations between qgroups.
   */
  struct btrfs_qgroup_list {
  	struct list_head next_group;
  	struct list_head next_member;
  	struct btrfs_qgroup *group;
  	struct btrfs_qgroup *member;
  };

  static inline u64 qgroup_to_aux(struct btrfs_qgroup *qg)
  {
  	return (u64)(uintptr_t)qg;
  }
  
  static inline struct btrfs_qgroup* unode_aux_to_qgroup(struct ulist_node *n)
  {
  	return (struct btrfs_qgroup *)(uintptr_t)n->aux;
  }

  static int
  qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,
  		   int init_flags);
  static void qgroup_rescan_zero_tracking(struct btrfs_fs_info *fs_info);

  /* must be called with qgroup_ioctl_lock held */

  static struct btrfs_qgroup *find_qgroup_rb(struct btrfs_fs_info *fs_info,
  					   u64 qgroupid)
  {
  	struct rb_node *n = fs_info->qgroup_tree.rb_node;
  	struct btrfs_qgroup *qgroup;
  
  	while (n) {
  		qgroup = rb_entry(n, struct btrfs_qgroup, node);
  		if (qgroup->qgroupid < qgroupid)
  			n = n->rb_left;
  		else if (qgroup->qgroupid > qgroupid)
  			n = n->rb_right;
  		else
  			return qgroup;
  	}
  	return NULL;
  }
  
  /* must be called with qgroup_lock held */
  static struct btrfs_qgroup *add_qgroup_rb(struct btrfs_fs_info *fs_info,
  					  u64 qgroupid)
  {
  	struct rb_node **p = &fs_info->qgroup_tree.rb_node;
  	struct rb_node *parent = NULL;
  	struct btrfs_qgroup *qgroup;
  
  	while (*p) {
  		parent = *p;
  		qgroup = rb_entry(parent, struct btrfs_qgroup, node);
  
  		if (qgroup->qgroupid < qgroupid)
  			p = &(*p)->rb_left;
  		else if (qgroup->qgroupid > qgroupid)
  			p = &(*p)->rb_right;
  		else
  			return qgroup;
  	}
  
  	qgroup = kzalloc(sizeof(*qgroup), GFP_ATOMIC);
  	if (!qgroup)
  		return ERR_PTR(-ENOMEM);
  
  	qgroup->qgroupid = qgroupid;
  	INIT_LIST_HEAD(&qgroup->groups);
  	INIT_LIST_HEAD(&qgroup->members);
  	INIT_LIST_HEAD(&qgroup->dirty);
  
  	rb_link_node(&qgroup->node, parent, p);
  	rb_insert_color(&qgroup->node, &fs_info->qgroup_tree);
  
  	return qgroup;
  }

  static void __del_qgroup_rb(struct btrfs_fs_info *fs_info,
  			    struct btrfs_qgroup *qgroup)

  {

  	struct btrfs_qgroup_list *list;

  	btrfs_sysfs_del_one_qgroup(fs_info, qgroup);

  	list_del(&qgroup->dirty);

  	while (!list_empty(&qgroup->groups)) {
  		list = list_first_entry(&qgroup->groups,
  					struct btrfs_qgroup_list, next_group);
  		list_del(&list->next_group);
  		list_del(&list->next_member);
  		kfree(list);
  	}
  
  	while (!list_empty(&qgroup->members)) {
  		list = list_first_entry(&qgroup->members,
  					struct btrfs_qgroup_list, next_member);
  		list_del(&list->next_group);
  		list_del(&list->next_member);
  		kfree(list);
  	}
  	kfree(qgroup);

  }

  /* must be called with qgroup_lock held */
  static int del_qgroup_rb(struct btrfs_fs_info *fs_info, u64 qgroupid)
  {
  	struct btrfs_qgroup *qgroup = find_qgroup_rb(fs_info, qgroupid);
  
  	if (!qgroup)
  		return -ENOENT;
  
  	rb_erase(&qgroup->node, &fs_info->qgroup_tree);

  	__del_qgroup_rb(fs_info, qgroup);

  	return 0;
  }
  
  /* must be called with qgroup_lock held */
  static int add_relation_rb(struct btrfs_fs_info *fs_info,
  			   u64 memberid, u64 parentid)
  {
  	struct btrfs_qgroup *member;
  	struct btrfs_qgroup *parent;
  	struct btrfs_qgroup_list *list;
  
  	member = find_qgroup_rb(fs_info, memberid);
  	parent = find_qgroup_rb(fs_info, parentid);
  	if (!member || !parent)
  		return -ENOENT;
  
  	list = kzalloc(sizeof(*list), GFP_ATOMIC);
  	if (!list)
  		return -ENOMEM;
  
  	list->group = parent;
  	list->member = member;
  	list_add_tail(&list->next_group, &member->groups);
  	list_add_tail(&list->next_member, &parent->members);
  
  	return 0;
  }
  
  /* must be called with qgroup_lock held */
  static int del_relation_rb(struct btrfs_fs_info *fs_info,
  			   u64 memberid, u64 parentid)
  {
  	struct btrfs_qgroup *member;
  	struct btrfs_qgroup *parent;
  	struct btrfs_qgroup_list *list;
  
  	member = find_qgroup_rb(fs_info, memberid);
  	parent = find_qgroup_rb(fs_info, parentid);
  	if (!member || !parent)
  		return -ENOENT;
  
  	list_for_each_entry(list, &member->groups, next_group) {
  		if (list->group == parent) {
  			list_del(&list->next_group);
  			list_del(&list->next_member);
  			kfree(list);
  			return 0;
  		}
  	}
  	return -ENOENT;
  }

  #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
  int btrfs_verify_qgroup_counts(struct btrfs_fs_info *fs_info, u64 qgroupid,
  			       u64 rfer, u64 excl)
  {
  	struct btrfs_qgroup *qgroup;
  
  	qgroup = find_qgroup_rb(fs_info, qgroupid);
  	if (!qgroup)
  		return -EINVAL;
  	if (qgroup->rfer != rfer || qgroup->excl != excl)
  		return -EINVAL;
  	return 0;
  }
  #endif

  /*
   * The full config is read in one go, only called from open_ctree()
   * It doesn't use any locking, as at this point we're still single-threaded
   */
  int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info)
  {
  	struct btrfs_key key;
  	struct btrfs_key found_key;
  	struct btrfs_root *quota_root = fs_info->quota_root;
  	struct btrfs_path *path = NULL;
  	struct extent_buffer *l;
  	int slot;
  	int ret = 0;
  	u64 flags = 0;

  	u64 rescan_progress = 0;

  	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))

  		return 0;

  	fs_info->qgroup_ulist = ulist_alloc(GFP_KERNEL);

  	if (!fs_info->qgroup_ulist) {
  		ret = -ENOMEM;
  		goto out;
  	}

  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}

  	ret = btrfs_sysfs_add_qgroups(fs_info);
  	if (ret < 0)
  		goto out;

  	/* default this to quota off, in case no status key is found */
  	fs_info->qgroup_flags = 0;
  
  	/*
  	 * pass 1: read status, all qgroup infos and limits
  	 */
  	key.objectid = 0;
  	key.type = 0;
  	key.offset = 0;
  	ret = btrfs_search_slot_for_read(quota_root, &key, path, 1, 1);
  	if (ret)
  		goto out;
  
  	while (1) {
  		struct btrfs_qgroup *qgroup;
  
  		slot = path->slots[0];
  		l = path->nodes[0];
  		btrfs_item_key_to_cpu(l, &found_key, slot);
  
  		if (found_key.type == BTRFS_QGROUP_STATUS_KEY) {
  			struct btrfs_qgroup_status_item *ptr;
  
  			ptr = btrfs_item_ptr(l, slot,
  					     struct btrfs_qgroup_status_item);
  
  			if (btrfs_qgroup_status_version(l, ptr) !=
  			    BTRFS_QGROUP_STATUS_VERSION) {

  				btrfs_err(fs_info,
  				 "old qgroup version, quota disabled");

  				goto out;
  			}
  			if (btrfs_qgroup_status_generation(l, ptr) !=
  			    fs_info->generation) {
  				flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;

  				btrfs_err(fs_info,

  					"qgroup generation mismatch, marked as inconsistent");

  			}
  			fs_info->qgroup_flags = btrfs_qgroup_status_flags(l,
  									  ptr);

  			rescan_progress = btrfs_qgroup_status_rescan(l, ptr);

  			goto next1;
  		}
  
  		if (found_key.type != BTRFS_QGROUP_INFO_KEY &&
  		    found_key.type != BTRFS_QGROUP_LIMIT_KEY)
  			goto next1;
  
  		qgroup = find_qgroup_rb(fs_info, found_key.offset);
  		if ((qgroup && found_key.type == BTRFS_QGROUP_INFO_KEY) ||
  		    (!qgroup && found_key.type == BTRFS_QGROUP_LIMIT_KEY)) {

  			btrfs_err(fs_info, "inconsistent qgroup config");

  			flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
  		}
  		if (!qgroup) {
  			qgroup = add_qgroup_rb(fs_info, found_key.offset);
  			if (IS_ERR(qgroup)) {
  				ret = PTR_ERR(qgroup);
  				goto out;
  			}
  		}

  		ret = btrfs_sysfs_add_one_qgroup(fs_info, qgroup);
  		if (ret < 0)
  			goto out;

  		switch (found_key.type) {
  		case BTRFS_QGROUP_INFO_KEY: {
  			struct btrfs_qgroup_info_item *ptr;
  
  			ptr = btrfs_item_ptr(l, slot,
  					     struct btrfs_qgroup_info_item);
  			qgroup->rfer = btrfs_qgroup_info_rfer(l, ptr);
  			qgroup->rfer_cmpr = btrfs_qgroup_info_rfer_cmpr(l, ptr);
  			qgroup->excl = btrfs_qgroup_info_excl(l, ptr);
  			qgroup->excl_cmpr = btrfs_qgroup_info_excl_cmpr(l, ptr);
  			/* generation currently unused */
  			break;
  		}
  		case BTRFS_QGROUP_LIMIT_KEY: {
  			struct btrfs_qgroup_limit_item *ptr;
  
  			ptr = btrfs_item_ptr(l, slot,
  					     struct btrfs_qgroup_limit_item);
  			qgroup->lim_flags = btrfs_qgroup_limit_flags(l, ptr);
  			qgroup->max_rfer = btrfs_qgroup_limit_max_rfer(l, ptr);
  			qgroup->max_excl = btrfs_qgroup_limit_max_excl(l, ptr);
  			qgroup->rsv_rfer = btrfs_qgroup_limit_rsv_rfer(l, ptr);
  			qgroup->rsv_excl = btrfs_qgroup_limit_rsv_excl(l, ptr);
  			break;
  		}
  		}
  next1:
  		ret = btrfs_next_item(quota_root, path);
  		if (ret < 0)
  			goto out;
  		if (ret)
  			break;
  	}
  	btrfs_release_path(path);
  
  	/*
  	 * pass 2: read all qgroup relations
  	 */
  	key.objectid = 0;
  	key.type = BTRFS_QGROUP_RELATION_KEY;
  	key.offset = 0;
  	ret = btrfs_search_slot_for_read(quota_root, &key, path, 1, 0);
  	if (ret)
  		goto out;
  	while (1) {
  		slot = path->slots[0];
  		l = path->nodes[0];
  		btrfs_item_key_to_cpu(l, &found_key, slot);
  
  		if (found_key.type != BTRFS_QGROUP_RELATION_KEY)
  			goto next2;
  
  		if (found_key.objectid > found_key.offset) {
  			/* parent <- member, not needed to build config */
  			/* FIXME should we omit the key completely? */
  			goto next2;
  		}
  
  		ret = add_relation_rb(fs_info, found_key.objectid,
  				      found_key.offset);

  		if (ret == -ENOENT) {

  			btrfs_warn(fs_info,
  				"orphan qgroup relation 0x%llx->0x%llx",

  				found_key.objectid, found_key.offset);

  			ret = 0;	/* ignore the error */
  		}

  		if (ret)
  			goto out;
  next2:
  		ret = btrfs_next_item(quota_root, path);
  		if (ret < 0)
  			goto out;
  		if (ret)
  			break;
  	}
  out:
  	fs_info->qgroup_flags |= flags;

  	if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON))
  		clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
  	else if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN &&
  		 ret >= 0)

  		ret = qgroup_rescan_init(fs_info, rescan_progress, 0);

  	btrfs_free_path(path);

  	if (ret < 0) {

  		ulist_free(fs_info->qgroup_ulist);

  		fs_info->qgroup_ulist = NULL;

  		fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;

  		btrfs_sysfs_del_qgroups(fs_info);

  	}

  	return ret < 0 ? ret : 0;
  }

  /*
   * Called in close_ctree() when quota is still enabled.  This verifies we don't
   * leak some reserved space.
   *
   * Return false if no reserved space is left.
   * Return true if some reserved space is leaked.
   */
  bool btrfs_check_quota_leak(struct btrfs_fs_info *fs_info)
  {
  	struct rb_node *node;
  	bool ret = false;
  
  	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
  		return ret;
  	/*
  	 * Since we're unmounting, there is no race and no need to grab qgroup
  	 * lock.  And here we don't go post-order to provide a more user
  	 * friendly sorted result.
  	 */
  	for (node = rb_first(&fs_info->qgroup_tree); node; node = rb_next(node)) {
  		struct btrfs_qgroup *qgroup;
  		int i;
  
  		qgroup = rb_entry(node, struct btrfs_qgroup, node);
  		for (i = 0; i < BTRFS_QGROUP_RSV_LAST; i++) {
  			if (qgroup->rsv.values[i]) {
  				ret = true;
  				btrfs_warn(fs_info,

  		"qgroup %hu/%llu has unreleased space, type %d rsv %llu",

  				   btrfs_qgroup_level(qgroup->qgroupid),
  				   btrfs_qgroup_subvolid(qgroup->qgroupid),
  				   i, qgroup->rsv.values[i]);
  			}
  		}
  	}
  	return ret;
  }

  /*

   * This is called from close_ctree() or open_ctree() or btrfs_quota_disable(),
   * first two are in single-threaded paths.And for the third one, we have set
   * quota_root to be null with qgroup_lock held before, so it is safe to clean
   * up the in-memory structures without qgroup_lock held.

   */
  void btrfs_free_qgroup_config(struct btrfs_fs_info *fs_info)
  {
  	struct rb_node *n;
  	struct btrfs_qgroup *qgroup;

  
  	while ((n = rb_first(&fs_info->qgroup_tree))) {
  		qgroup = rb_entry(n, struct btrfs_qgroup, node);
  		rb_erase(n, &fs_info->qgroup_tree);

  		__del_qgroup_rb(fs_info, qgroup);

  	}

  	/*

  	 * We call btrfs_free_qgroup_config() when unmounting

  	 * filesystem and disabling quota, so we set qgroup_ulist

  	 * to be null here to avoid double free.
  	 */

  	ulist_free(fs_info->qgroup_ulist);

  	fs_info->qgroup_ulist = NULL;

  	btrfs_sysfs_del_qgroups(fs_info);

  }

  static int add_qgroup_relation_item(struct btrfs_trans_handle *trans, u64 src,
  				    u64 dst)

  {
  	int ret;

  	struct btrfs_root *quota_root = trans->fs_info->quota_root;

  	struct btrfs_path *path;
  	struct btrfs_key key;
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = src;
  	key.type = BTRFS_QGROUP_RELATION_KEY;
  	key.offset = dst;
  
  	ret = btrfs_insert_empty_item(trans, quota_root, path, &key, 0);
  
  	btrfs_mark_buffer_dirty(path->nodes[0]);
  
  	btrfs_free_path(path);
  	return ret;
  }

  static int del_qgroup_relation_item(struct btrfs_trans_handle *trans, u64 src,
  				    u64 dst)

  {
  	int ret;

  	struct btrfs_root *quota_root = trans->fs_info->quota_root;

  	struct btrfs_path *path;
  	struct btrfs_key key;
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = src;
  	key.type = BTRFS_QGROUP_RELATION_KEY;
  	key.offset = dst;
  
  	ret = btrfs_search_slot(trans, quota_root, &key, path, -1, 1);
  	if (ret < 0)
  		goto out;
  
  	if (ret > 0) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	ret = btrfs_del_item(trans, quota_root, path);
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int add_qgroup_item(struct btrfs_trans_handle *trans,
  			   struct btrfs_root *quota_root, u64 qgroupid)
  {
  	int ret;
  	struct btrfs_path *path;
  	struct btrfs_qgroup_info_item *qgroup_info;
  	struct btrfs_qgroup_limit_item *qgroup_limit;
  	struct extent_buffer *leaf;
  	struct btrfs_key key;

  	if (btrfs_is_testing(quota_root->fs_info))

  		return 0;

  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = 0;
  	key.type = BTRFS_QGROUP_INFO_KEY;
  	key.offset = qgroupid;

  	/*
  	 * Avoid a transaction abort by catching -EEXIST here. In that
  	 * case, we proceed by re-initializing the existing structure
  	 * on disk.
  	 */

  	ret = btrfs_insert_empty_item(trans, quota_root, path, &key,
  				      sizeof(*qgroup_info));

  	if (ret && ret != -EEXIST)

  		goto out;
  
  	leaf = path->nodes[0];
  	qgroup_info = btrfs_item_ptr(leaf, path->slots[0],
  				 struct btrfs_qgroup_info_item);
  	btrfs_set_qgroup_info_generation(leaf, qgroup_info, trans->transid);
  	btrfs_set_qgroup_info_rfer(leaf, qgroup_info, 0);
  	btrfs_set_qgroup_info_rfer_cmpr(leaf, qgroup_info, 0);
  	btrfs_set_qgroup_info_excl(leaf, qgroup_info, 0);
  	btrfs_set_qgroup_info_excl_cmpr(leaf, qgroup_info, 0);
  
  	btrfs_mark_buffer_dirty(leaf);
  
  	btrfs_release_path(path);
  
  	key.type = BTRFS_QGROUP_LIMIT_KEY;
  	ret = btrfs_insert_empty_item(trans, quota_root, path, &key,
  				      sizeof(*qgroup_limit));

  	if (ret && ret != -EEXIST)

  		goto out;
  
  	leaf = path->nodes[0];
  	qgroup_limit = btrfs_item_ptr(leaf, path->slots[0],
  				  struct btrfs_qgroup_limit_item);
  	btrfs_set_qgroup_limit_flags(leaf, qgroup_limit, 0);
  	btrfs_set_qgroup_limit_max_rfer(leaf, qgroup_limit, 0);
  	btrfs_set_qgroup_limit_max_excl(leaf, qgroup_limit, 0);
  	btrfs_set_qgroup_limit_rsv_rfer(leaf, qgroup_limit, 0);
  	btrfs_set_qgroup_limit_rsv_excl(leaf, qgroup_limit, 0);
  
  	btrfs_mark_buffer_dirty(leaf);
  
  	ret = 0;
  out:
  	btrfs_free_path(path);
  	return ret;
  }

  static int del_qgroup_item(struct btrfs_trans_handle *trans, u64 qgroupid)

  {
  	int ret;

  	struct btrfs_root *quota_root = trans->fs_info->quota_root;

  	struct btrfs_path *path;
  	struct btrfs_key key;
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = 0;
  	key.type = BTRFS_QGROUP_INFO_KEY;
  	key.offset = qgroupid;
  	ret = btrfs_search_slot(trans, quota_root, &key, path, -1, 1);
  	if (ret < 0)
  		goto out;
  
  	if (ret > 0) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	ret = btrfs_del_item(trans, quota_root, path);
  	if (ret)
  		goto out;
  
  	btrfs_release_path(path);
  
  	key.type = BTRFS_QGROUP_LIMIT_KEY;
  	ret = btrfs_search_slot(trans, quota_root, &key, path, -1, 1);
  	if (ret < 0)
  		goto out;
  
  	if (ret > 0) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	ret = btrfs_del_item(trans, quota_root, path);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int update_qgroup_limit_item(struct btrfs_trans_handle *trans,

  				    struct btrfs_qgroup *qgroup)

  {

  	struct btrfs_root *quota_root = trans->fs_info->quota_root;

  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct extent_buffer *l;
  	struct btrfs_qgroup_limit_item *qgroup_limit;
  	int ret;
  	int slot;
  
  	key.objectid = 0;
  	key.type = BTRFS_QGROUP_LIMIT_KEY;

  	key.offset = qgroup->qgroupid;

  
  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  	ret = btrfs_search_slot(trans, quota_root, &key, path, 0, 1);

  	if (ret > 0)
  		ret = -ENOENT;
  
  	if (ret)
  		goto out;
  
  	l = path->nodes[0];
  	slot = path->slots[0];

  	qgroup_limit = btrfs_item_ptr(l, slot, struct btrfs_qgroup_limit_item);

  	btrfs_set_qgroup_limit_flags(l, qgroup_limit, qgroup->lim_flags);
  	btrfs_set_qgroup_limit_max_rfer(l, qgroup_limit, qgroup->max_rfer);
  	btrfs_set_qgroup_limit_max_excl(l, qgroup_limit, qgroup->max_excl);
  	btrfs_set_qgroup_limit_rsv_rfer(l, qgroup_limit, qgroup->rsv_rfer);
  	btrfs_set_qgroup_limit_rsv_excl(l, qgroup_limit, qgroup->rsv_excl);

  
  	btrfs_mark_buffer_dirty(l);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int update_qgroup_info_item(struct btrfs_trans_handle *trans,

  				   struct btrfs_qgroup *qgroup)
  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;
  	struct btrfs_root *quota_root = fs_info->quota_root;

  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct extent_buffer *l;
  	struct btrfs_qgroup_info_item *qgroup_info;
  	int ret;
  	int slot;

  	if (btrfs_is_testing(fs_info))

  		return 0;

  	key.objectid = 0;
  	key.type = BTRFS_QGROUP_INFO_KEY;
  	key.offset = qgroup->qgroupid;
  
  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  	ret = btrfs_search_slot(trans, quota_root, &key, path, 0, 1);

  	if (ret > 0)
  		ret = -ENOENT;
  
  	if (ret)
  		goto out;
  
  	l = path->nodes[0];
  	slot = path->slots[0];

  	qgroup_info = btrfs_item_ptr(l, slot, struct btrfs_qgroup_info_item);

  	btrfs_set_qgroup_info_generation(l, qgroup_info, trans->transid);
  	btrfs_set_qgroup_info_rfer(l, qgroup_info, qgroup->rfer);
  	btrfs_set_qgroup_info_rfer_cmpr(l, qgroup_info, qgroup->rfer_cmpr);
  	btrfs_set_qgroup_info_excl(l, qgroup_info, qgroup->excl);
  	btrfs_set_qgroup_info_excl_cmpr(l, qgroup_info, qgroup->excl_cmpr);
  
  	btrfs_mark_buffer_dirty(l);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }

  static int update_qgroup_status_item(struct btrfs_trans_handle *trans)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;
  	struct btrfs_root *quota_root = fs_info->quota_root;

  	struct btrfs_path *path;
  	struct btrfs_key key;
  	struct extent_buffer *l;
  	struct btrfs_qgroup_status_item *ptr;
  	int ret;
  	int slot;
  
  	key.objectid = 0;
  	key.type = BTRFS_QGROUP_STATUS_KEY;
  	key.offset = 0;
  
  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  	ret = btrfs_search_slot(trans, quota_root, &key, path, 0, 1);

  	if (ret > 0)
  		ret = -ENOENT;
  
  	if (ret)
  		goto out;
  
  	l = path->nodes[0];
  	slot = path->slots[0];
  	ptr = btrfs_item_ptr(l, slot, struct btrfs_qgroup_status_item);
  	btrfs_set_qgroup_status_flags(l, ptr, fs_info->qgroup_flags);
  	btrfs_set_qgroup_status_generation(l, ptr, trans->transid);

  	btrfs_set_qgroup_status_rescan(l, ptr,
  				fs_info->qgroup_rescan_progress.objectid);

  
  	btrfs_mark_buffer_dirty(l);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  /*
   * called with qgroup_lock held
   */
  static int btrfs_clean_quota_tree(struct btrfs_trans_handle *trans,
  				  struct btrfs_root *root)
  {
  	struct btrfs_path *path;
  	struct btrfs_key key;

  	struct extent_buffer *leaf = NULL;

  	int ret;

  	int nr = 0;

  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;

  	path->leave_spinning = 1;
  
  	key.objectid = 0;
  	key.offset = 0;
  	key.type = 0;

  	while (1) {

  		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);

  		if (ret < 0)
  			goto out;
  		leaf = path->nodes[0];
  		nr = btrfs_header_nritems(leaf);
  		if (!nr)

  			break;

  		/*
  		 * delete the leaf one by one
  		 * since the whole tree is going
  		 * to be deleted.
  		 */
  		path->slots[0] = 0;
  		ret = btrfs_del_items(trans, root, path, 0, nr);

  		if (ret)
  			goto out;

  		btrfs_release_path(path);
  	}
  	ret = 0;
  out:

  	btrfs_free_path(path);
  	return ret;
  }

  int btrfs_quota_enable(struct btrfs_fs_info *fs_info)

  {
  	struct btrfs_root *quota_root;

  	struct btrfs_root *tree_root = fs_info->tree_root;

  	struct btrfs_path *path = NULL;
  	struct btrfs_qgroup_status_item *ptr;
  	struct extent_buffer *leaf;
  	struct btrfs_key key;

  	struct btrfs_key found_key;
  	struct btrfs_qgroup *qgroup = NULL;

  	struct btrfs_trans_handle *trans = NULL;

  	int ret = 0;

  	int slot;

  	mutex_lock(&fs_info->qgroup_ioctl_lock);

  	if (fs_info->quota_root)

  		goto out;

  	fs_info->qgroup_ulist = ulist_alloc(GFP_KERNEL);
  	if (!fs_info->qgroup_ulist) {
  		ret = -ENOMEM;
  		goto out;
  	}

  	ret = btrfs_sysfs_add_qgroups(fs_info);
  	if (ret < 0)
  		goto out;

  	/*
  	 * 1 for quota root item
  	 * 1 for BTRFS_QGROUP_STATUS item
  	 *
  	 * Yet we also need 2*n items for a QGROUP_INFO/QGROUP_LIMIT items
  	 * per subvolume. However those are not currently reserved since it
  	 * would be a lot of overkill.
  	 */
  	trans = btrfs_start_transaction(tree_root, 2);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		trans = NULL;
  		goto out;
  	}

  	/*
  	 * initially create the quota tree
  	 */

  	quota_root = btrfs_create_tree(trans, BTRFS_QUOTA_TREE_OBJECTID);

  	if (IS_ERR(quota_root)) {
  		ret =  PTR_ERR(quota_root);

  		btrfs_abort_transaction(trans, ret);

  		goto out;
  	}
  
  	path = btrfs_alloc_path();

  	if (!path) {
  		ret = -ENOMEM;

  		btrfs_abort_transaction(trans, ret);

  		goto out_free_root;
  	}

  
  	key.objectid = 0;
  	key.type = BTRFS_QGROUP_STATUS_KEY;
  	key.offset = 0;
  
  	ret = btrfs_insert_empty_item(trans, quota_root, path, &key,
  				      sizeof(*ptr));

  	if (ret) {
  		btrfs_abort_transaction(trans, ret);

  		goto out_free_path;

  	}

  
  	leaf = path->nodes[0];
  	ptr = btrfs_item_ptr(leaf, path->slots[0],
  				 struct btrfs_qgroup_status_item);
  	btrfs_set_qgroup_status_generation(leaf, ptr, trans->transid);
  	btrfs_set_qgroup_status_version(leaf, ptr, BTRFS_QGROUP_STATUS_VERSION);
  	fs_info->qgroup_flags = BTRFS_QGROUP_STATUS_FLAG_ON |
  				BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
  	btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags);

  	btrfs_set_qgroup_status_rescan(leaf, ptr, 0);

  
  	btrfs_mark_buffer_dirty(leaf);

  	key.objectid = 0;
  	key.type = BTRFS_ROOT_REF_KEY;
  	key.offset = 0;
  
  	btrfs_release_path(path);
  	ret = btrfs_search_slot_for_read(tree_root, &key, path, 1, 0);
  	if (ret > 0)
  		goto out_add_root;

  	if (ret < 0) {
  		btrfs_abort_transaction(trans, ret);

  		goto out_free_path;

  	}

  
  	while (1) {
  		slot = path->slots[0];
  		leaf = path->nodes[0];
  		btrfs_item_key_to_cpu(leaf, &found_key, slot);
  
  		if (found_key.type == BTRFS_ROOT_REF_KEY) {
  			ret = add_qgroup_item(trans, quota_root,
  					      found_key.offset);

  			if (ret) {
  				btrfs_abort_transaction(trans, ret);

  				goto out_free_path;

  			}

  			qgroup = add_qgroup_rb(fs_info, found_key.offset);
  			if (IS_ERR(qgroup)) {

  				ret = PTR_ERR(qgroup);

  				btrfs_abort_transaction(trans, ret);

  				goto out_free_path;
  			}

  			ret = btrfs_sysfs_add_one_qgroup(fs_info, qgroup);
  			if (ret < 0) {
  				btrfs_abort_transaction(trans, ret);
  				goto out_free_path;
  			}

  		}
  		ret = btrfs_next_item(tree_root, path);

  		if (ret < 0) {
  			btrfs_abort_transaction(trans, ret);

  			goto out_free_path;

  		}

  		if (ret)
  			break;
  	}
  
  out_add_root:
  	btrfs_release_path(path);
  	ret = add_qgroup_item(trans, quota_root, BTRFS_FS_TREE_OBJECTID);

  	if (ret) {
  		btrfs_abort_transaction(trans, ret);

  		goto out_free_path;

  	}

  	qgroup = add_qgroup_rb(fs_info, BTRFS_FS_TREE_OBJECTID);
  	if (IS_ERR(qgroup)) {

  		ret = PTR_ERR(qgroup);

  		btrfs_abort_transaction(trans, ret);

  		goto out_free_path;
  	}

  	ret = btrfs_sysfs_add_one_qgroup(fs_info, qgroup);
  	if (ret < 0) {
  		btrfs_abort_transaction(trans, ret);
  		goto out_free_path;
  	}

  
  	ret = btrfs_commit_transaction(trans);

  	trans = NULL;
  	if (ret)

  		goto out_free_path;

  	/*
  	 * Set quota enabled flag after committing the transaction, to avoid
  	 * deadlocks on fs_info->qgroup_ioctl_lock with concurrent snapshot
  	 * creation.
  	 */
  	spin_lock(&fs_info->qgroup_lock);
  	fs_info->quota_root = quota_root;
  	set_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
  	spin_unlock(&fs_info->qgroup_lock);

  	ret = qgroup_rescan_init(fs_info, 0, 1);
  	if (!ret) {
  	        qgroup_rescan_zero_tracking(fs_info);

  		fs_info->qgroup_rescan_running = true;

  	        btrfs_queue_work(fs_info->qgroup_rescan_workers,
  	                         &fs_info->qgroup_rescan_work);
  	}

  out_free_path:

  	btrfs_free_path(path);

  out_free_root:

  	if (ret)

  		btrfs_put_root(quota_root);

  out:

  	if (ret) {

  		ulist_free(fs_info->qgroup_ulist);

  		fs_info->qgroup_ulist = NULL;

  		if (trans)
  			btrfs_end_transaction(trans);

  		btrfs_sysfs_del_qgroups(fs_info);

  	}

  	mutex_unlock(&fs_info->qgroup_ioctl_lock);

  	return ret;
  }

  int btrfs_quota_disable(struct btrfs_fs_info *fs_info)

  {

  	struct btrfs_root *quota_root;

  	struct btrfs_trans_handle *trans = NULL;

  	int ret = 0;

  	mutex_lock(&fs_info->qgroup_ioctl_lock);

  	if (!fs_info->quota_root)

  		goto out;

  
  	/*
  	 * 1 For the root item
  	 *
  	 * We should also reserve enough items for the quota tree deletion in
  	 * btrfs_clean_quota_tree but this is not done.
  	 */
  	trans = btrfs_start_transaction(fs_info->tree_root, 1);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out;
  	}

  	clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);

  	btrfs_qgroup_wait_for_completion(fs_info, false);

  	spin_lock(&fs_info->qgroup_lock);

  	quota_root = fs_info->quota_root;
  	fs_info->quota_root = NULL;

  	fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_ON;

  	spin_unlock(&fs_info->qgroup_lock);

  	btrfs_free_qgroup_config(fs_info);

  	ret = btrfs_clean_quota_tree(trans, quota_root);

  	if (ret) {
  		btrfs_abort_transaction(trans, ret);
  		goto end_trans;
  	}

  	ret = btrfs_del_root(trans, &quota_root->root_key);

  	if (ret) {
  		btrfs_abort_transaction(trans, ret);
  		goto end_trans;
  	}

  
  	list_del(&quota_root->dirty_list);
  
  	btrfs_tree_lock(quota_root->node);

  	btrfs_clean_tree_block(quota_root->node);

  	btrfs_tree_unlock(quota_root->node);
  	btrfs_free_tree_block(trans, quota_root, quota_root->node, 0, 1);

  	btrfs_put_root(quota_root);

  
  end_trans:
  	ret = btrfs_end_transaction(trans);

  out:

  	mutex_unlock(&fs_info->qgroup_ioctl_lock);

  	return ret;
  }

  static void qgroup_dirty(struct btrfs_fs_info *fs_info,
  			 struct btrfs_qgroup *qgroup)

  {

  	if (list_empty(&qgroup->dirty))
  		list_add(&qgroup->dirty, &fs_info->dirty_qgroups);

  }

  /*

   * The easy accounting, we're updating qgroup relationship whose child qgroup
   * only has exclusive extents.
   *

   * In this case, all exclusive extents will also be exclusive for parent, so

   * excl/rfer just get added/removed.
   *
   * So is qgroup reservation space, which should also be added/removed to
   * parent.
   * Or when child tries to release reservation space, parent will underflow its
   * reservation (for relationship adding case).

   *
   * Caller should hold fs_info->qgroup_lock.
   */
  static int __qgroup_excl_accounting(struct btrfs_fs_info *fs_info,
  				    struct ulist *tmp, u64 ref_root,

  				    struct btrfs_qgroup *src, int sign)

  {
  	struct btrfs_qgroup *qgroup;
  	struct btrfs_qgroup_list *glist;
  	struct ulist_node *unode;
  	struct ulist_iterator uiter;

  	u64 num_bytes = src->excl;

  	int ret = 0;
  
  	qgroup = find_qgroup_rb(fs_info, ref_root);
  	if (!qgroup)
  		goto out;
  
  	qgroup->rfer += sign * num_bytes;
  	qgroup->rfer_cmpr += sign * num_bytes;
  
  	WARN_ON(sign < 0 && qgroup->excl < num_bytes);
  	qgroup->excl += sign * num_bytes;
  	qgroup->excl_cmpr += sign * num_bytes;

  
  	if (sign > 0)

  		qgroup_rsv_add_by_qgroup(fs_info, qgroup, src);

  	else

  		qgroup_rsv_release_by_qgroup(fs_info, qgroup, src);

  
  	qgroup_dirty(fs_info, qgroup);
  
  	/* Get all of the parent groups that contain this qgroup */
  	list_for_each_entry(glist, &qgroup->groups, next_group) {
  		ret = ulist_add(tmp, glist->group->qgroupid,

  				qgroup_to_aux(glist->group), GFP_ATOMIC);

  		if (ret < 0)
  			goto out;
  	}
  
  	/* Iterate all of the parents and adjust their reference counts */
  	ULIST_ITER_INIT(&uiter);
  	while ((unode = ulist_next(tmp, &uiter))) {

  		qgroup = unode_aux_to_qgroup(unode);

  		qgroup->rfer += sign * num_bytes;
  		qgroup->rfer_cmpr += sign * num_bytes;
  		WARN_ON(sign < 0 && qgroup->excl < num_bytes);
  		qgroup->excl += sign * num_bytes;

  		if (sign > 0)

  			qgroup_rsv_add_by_qgroup(fs_info, qgroup, src);

  		else

  			qgroup_rsv_release_by_qgroup(fs_info, qgroup, src);

  		qgroup->excl_cmpr += sign * num_bytes;
  		qgroup_dirty(fs_info, qgroup);
  
  		/* Add any parents of the parents */
  		list_for_each_entry(glist, &qgroup->groups, next_group) {
  			ret = ulist_add(tmp, glist->group->qgroupid,

  					qgroup_to_aux(glist->group), GFP_ATOMIC);

  			if (ret < 0)
  				goto out;
  		}
  	}
  	ret = 0;
  out:
  	return ret;
  }
  
  
  /*
   * Quick path for updating qgroup with only excl refs.
   *
   * In that case, just update all parent will be enough.
   * Or we needs to do a full rescan.
   * Caller should also hold fs_info->qgroup_lock.
   *
   * Return 0 for quick update, return >0 for need to full rescan
   * and mark INCONSISTENT flag.
   * Return < 0 for other error.
   */
  static int quick_update_accounting(struct btrfs_fs_info *fs_info,
  				   struct ulist *tmp, u64 src, u64 dst,
  				   int sign)
  {
  	struct btrfs_qgroup *qgroup;
  	int ret = 1;
  	int err = 0;
  
  	qgroup = find_qgroup_rb(fs_info, src);
  	if (!qgroup)
  		goto out;
  	if (qgroup->excl == qgroup->rfer) {
  		ret = 0;
  		err = __qgroup_excl_accounting(fs_info, tmp, dst,

  					       qgroup, sign);

  		if (err < 0) {
  			ret = err;
  			goto out;
  		}
  	}
  out:
  	if (ret)
  		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
  	return ret;
  }

  int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
  			      u64 dst)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_qgroup *parent;
  	struct btrfs_qgroup *member;

  	struct btrfs_qgroup_list *list;

  	struct ulist *tmp;

  	int ret = 0;

  	/* Check the level of src and dst first */
  	if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst))
  		return -EINVAL;

  	tmp = ulist_alloc(GFP_KERNEL);

  	if (!tmp)
  		return -ENOMEM;

  	mutex_lock(&fs_info->qgroup_ioctl_lock);

  	if (!fs_info->quota_root) {

  		ret = -ENOTCONN;

  		goto out;
  	}

  	member = find_qgroup_rb(fs_info, src);
  	parent = find_qgroup_rb(fs_info, dst);
  	if (!member || !parent) {
  		ret = -EINVAL;
  		goto out;
  	}

  	/* check if such qgroup relation exist firstly */
  	list_for_each_entry(list, &member->groups, next_group) {
  		if (list->group == parent) {
  			ret = -EEXIST;
  			goto out;
  		}
  	}

  	ret = add_qgroup_relation_item(trans, src, dst);

  	if (ret)

  		goto out;

  	ret = add_qgroup_relation_item(trans, dst, src);

  	if (ret) {

  		del_qgroup_relation_item(trans, src, dst);

  		goto out;

  	}
  
  	spin_lock(&fs_info->qgroup_lock);

  	ret = add_relation_rb(fs_info, src, dst);

  	if (ret < 0) {
  		spin_unlock(&fs_info->qgroup_lock);
  		goto out;
  	}
  	ret = quick_update_accounting(fs_info, tmp, src, dst, 1);

  	spin_unlock(&fs_info->qgroup_lock);

  out:
  	mutex_unlock(&fs_info->qgroup_ioctl_lock);

  	ulist_free(tmp);

  	return ret;
  }

  static int __del_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
  				 u64 dst)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_qgroup *parent;
  	struct btrfs_qgroup *member;
  	struct btrfs_qgroup_list *list;

  	struct ulist *tmp;

  	bool found = false;

  	int ret = 0;

  	int ret2;

  	tmp = ulist_alloc(GFP_KERNEL);

  	if (!tmp)
  		return -ENOMEM;

  	if (!fs_info->quota_root) {

  		ret = -ENOTCONN;

  		goto out;
  	}

  	member = find_qgroup_rb(fs_info, src);
  	parent = find_qgroup_rb(fs_info, dst);

  	/*
  	 * The parent/member pair doesn't exist, then try to delete the dead
  	 * relation items only.
  	 */
  	if (!member || !parent)
  		goto delete_item;

  
  	/* check if such qgroup relation exist firstly */
  	list_for_each_entry(list, &member->groups, next_group) {

  		if (list->group == parent) {
  			found = true;
  			break;
  		}

  	}

  
  delete_item:

  	ret = del_qgroup_relation_item(trans, src, dst);

  	if (ret < 0 && ret != -ENOENT)
  		goto out;
  	ret2 = del_qgroup_relation_item(trans, dst, src);
  	if (ret2 < 0 && ret2 != -ENOENT)
  		goto out;

  	/* At least one deletion succeeded, return 0 */
  	if (!ret || !ret2)
  		ret = 0;
  
  	if (found) {
  		spin_lock(&fs_info->qgroup_lock);
  		del_relation_rb(fs_info, src, dst);
  		ret = quick_update_accounting(fs_info, tmp, src, dst, -1);
  		spin_unlock(&fs_info->qgroup_lock);
  	}

  out:

  	ulist_free(tmp);

  	return ret;
  }

  int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
  			      u64 dst)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	int ret = 0;
  
  	mutex_lock(&fs_info->qgroup_ioctl_lock);

  	ret = __del_qgroup_relation(trans, src, dst);

  	mutex_unlock(&fs_info->qgroup_ioctl_lock);

  	return ret;
  }

  int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_root *quota_root;
  	struct btrfs_qgroup *qgroup;
  	int ret = 0;

  	mutex_lock(&fs_info->qgroup_ioctl_lock);

  	if (!fs_info->quota_root) {

  		ret = -ENOTCONN;

  		goto out;
  	}

  	quota_root = fs_info->quota_root;

  	qgroup = find_qgroup_rb(fs_info, qgroupid);
  	if (qgroup) {
  		ret = -EEXIST;
  		goto out;
  	}

  
  	ret = add_qgroup_item(trans, quota_root, qgroupid);

  	if (ret)
  		goto out;

  
  	spin_lock(&fs_info->qgroup_lock);
  	qgroup = add_qgroup_rb(fs_info, qgroupid);
  	spin_unlock(&fs_info->qgroup_lock);

  	if (IS_ERR(qgroup)) {

  		ret = PTR_ERR(qgroup);

  		goto out;
  	}
  	ret = btrfs_sysfs_add_one_qgroup(fs_info, qgroup);

  out:
  	mutex_unlock(&fs_info->qgroup_ioctl_lock);

  	return ret;
  }

  int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_qgroup *qgroup;

  	struct btrfs_qgroup_list *list;

  	int ret = 0;

  	mutex_lock(&fs_info->qgroup_ioctl_lock);

  	if (!fs_info->quota_root) {

  		ret = -ENOTCONN;

  		goto out;
  	}

  	qgroup = find_qgroup_rb(fs_info, qgroupid);

  	if (!qgroup) {
  		ret = -ENOENT;
  		goto out;

  	}

  
  	/* Check if there are no children of this qgroup */
  	if (!list_empty(&qgroup->members)) {
  		ret = -EBUSY;
  		goto out;
  	}

  	ret = del_qgroup_item(trans, qgroupid);

  	if (ret && ret != -ENOENT)
  		goto out;

  	while (!list_empty(&qgroup->groups)) {
  		list = list_first_entry(&qgroup->groups,
  					struct btrfs_qgroup_list, next_group);

  		ret = __del_qgroup_relation(trans, qgroupid,
  					    list->group->qgroupid);

  		if (ret)
  			goto out;
  	}

  	spin_lock(&fs_info->qgroup_lock);

  	del_qgroup_rb(fs_info, qgroupid);

  	spin_unlock(&fs_info->qgroup_lock);

  out:
  	mutex_unlock(&fs_info->qgroup_ioctl_lock);

  	return ret;
  }

  int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid,

  		       struct btrfs_qgroup_limit *limit)
  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_qgroup *qgroup;
  	int ret = 0;

  	/* Sometimes we would want to clear the limit on this qgroup.
  	 * To meet this requirement, we treat the -1 as a special value
  	 * which tell kernel to clear the limit on this qgroup.
  	 */
  	const u64 CLEAR_VALUE = -1;

  	mutex_lock(&fs_info->qgroup_ioctl_lock);

  	if (!fs_info->quota_root) {

  		ret = -ENOTCONN;

  		goto out;
  	}

  	qgroup = find_qgroup_rb(fs_info, qgroupid);
  	if (!qgroup) {
  		ret = -ENOENT;
  		goto out;
  	}

  	spin_lock(&fs_info->qgroup_lock);

  	if (limit->flags & BTRFS_QGROUP_LIMIT_MAX_RFER) {
  		if (limit->max_rfer == CLEAR_VALUE) {
  			qgroup->lim_flags &= ~BTRFS_QGROUP_LIMIT_MAX_RFER;
  			limit->flags &= ~BTRFS_QGROUP_LIMIT_MAX_RFER;
  			qgroup->max_rfer = 0;
  		} else {
  			qgroup->max_rfer = limit->max_rfer;
  		}
  	}
  	if (limit->flags & BTRFS_QGROUP_LIMIT_MAX_EXCL) {
  		if (limit->max_excl == CLEAR_VALUE) {
  			qgroup->lim_flags &= ~BTRFS_QGROUP_LIMIT_MAX_EXCL;
  			limit->flags &= ~BTRFS_QGROUP_LIMIT_MAX_EXCL;
  			qgroup->max_excl = 0;
  		} else {
  			qgroup->max_excl = limit->max_excl;
  		}
  	}
  	if (limit->flags & BTRFS_QGROUP_LIMIT_RSV_RFER) {
  		if (limit->rsv_rfer == CLEAR_VALUE) {
  			qgroup->lim_flags &= ~BTRFS_QGROUP_LIMIT_RSV_RFER;
  			limit->flags &= ~BTRFS_QGROUP_LIMIT_RSV_RFER;
  			qgroup->rsv_rfer = 0;
  		} else {
  			qgroup->rsv_rfer = limit->rsv_rfer;
  		}
  	}
  	if (limit->flags & BTRFS_QGROUP_LIMIT_RSV_EXCL) {
  		if (limit->rsv_excl == CLEAR_VALUE) {
  			qgroup->lim_flags &= ~BTRFS_QGROUP_LIMIT_RSV_EXCL;
  			limit->flags &= ~BTRFS_QGROUP_LIMIT_RSV_EXCL;
  			qgroup->rsv_excl = 0;
  		} else {
  			qgroup->rsv_excl = limit->rsv_excl;
  		}
  	}

  	qgroup->lim_flags |= limit->flags;

  	spin_unlock(&fs_info->qgroup_lock);

  	ret = update_qgroup_limit_item(trans, qgroup);

  	if (ret) {
  		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
  		btrfs_info(fs_info, "unable to update quota limit for %llu",
  		       qgroupid);
  	}

  out:
  	mutex_unlock(&fs_info->qgroup_ioctl_lock);

  	return ret;
  }

  int btrfs_qgroup_trace_extent_nolock(struct btrfs_fs_info *fs_info,

  				struct btrfs_delayed_ref_root *delayed_refs,
  				struct btrfs_qgroup_extent_record *record)

  {
  	struct rb_node **p = &delayed_refs->dirty_extent_root.rb_node;
  	struct rb_node *parent_node = NULL;
  	struct btrfs_qgroup_extent_record *entry;
  	u64 bytenr = record->bytenr;

  	lockdep_assert_held(&delayed_refs->lock);

  	trace_btrfs_qgroup_trace_extent(fs_info, record);

  	while (*p) {
  		parent_node = *p;
  		entry = rb_entry(parent_node, struct btrfs_qgroup_extent_record,
  				 node);

  		if (bytenr < entry->bytenr) {

  			p = &(*p)->rb_left;

  		} else if (bytenr > entry->bytenr) {

  			p = &(*p)->rb_right;

  		} else {
  			if (record->data_rsv && !entry->data_rsv) {
  				entry->data_rsv = record->data_rsv;
  				entry->data_rsv_refroot =
  					record->data_rsv_refroot;
  			}

  			return 1;

  		}

  	}
  
  	rb_link_node(&record->node, parent_node, p);
  	rb_insert_color(&record->node, &delayed_refs->dirty_extent_root);

  	return 0;
  }

  int btrfs_qgroup_trace_extent_post(struct btrfs_fs_info *fs_info,
  				   struct btrfs_qgroup_extent_record *qrecord)
  {
  	struct ulist *old_root;
  	u64 bytenr = qrecord->bytenr;
  	int ret;

  	ret = btrfs_find_all_roots(NULL, fs_info, bytenr, 0, &old_root, false);

  	if (ret < 0) {
  		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
  		btrfs_warn(fs_info,
  "error accounting new delayed refs extent (err code: %d), quota inconsistent",
  			ret);
  		return 0;
  	}

  
  	/*
  	 * Here we don't need to get the lock of
  	 * trans->transaction->delayed_refs, since inserted qrecord won't
  	 * be deleted, only qrecord->node may be modified (new qrecord insert)
  	 *
  	 * So modifying qrecord->old_roots is safe here
  	 */
  	qrecord->old_roots = old_root;
  	return 0;
  }

  int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr,
  			      u64 num_bytes, gfp_t gfp_flag)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_qgroup_extent_record *record;
  	struct btrfs_delayed_ref_root *delayed_refs;
  	int ret;

  	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)
  	    || bytenr == 0 || num_bytes == 0)

  		return 0;

  	record = kzalloc(sizeof(*record), gfp_flag);

  	if (!record)
  		return -ENOMEM;
  
  	delayed_refs = &trans->transaction->delayed_refs;
  	record->bytenr = bytenr;
  	record->num_bytes = num_bytes;
  	record->old_roots = NULL;
  
  	spin_lock(&delayed_refs->lock);

  	ret = btrfs_qgroup_trace_extent_nolock(fs_info, delayed_refs, record);

  	spin_unlock(&delayed_refs->lock);

  	if (ret > 0) {

  		kfree(record);

  		return 0;
  	}
  	return btrfs_qgroup_trace_extent_post(fs_info, record);

  }

  int btrfs_qgroup_trace_leaf_items(struct btrfs_trans_handle *trans,

  				  struct extent_buffer *eb)
  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	int nr = btrfs_header_nritems(eb);
  	int i, extent_type, ret;
  	struct btrfs_key key;
  	struct btrfs_file_extent_item *fi;
  	u64 bytenr, num_bytes;
  
  	/* We can be called directly from walk_up_proc() */

  	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))

  		return 0;
  
  	for (i = 0; i < nr; i++) {
  		btrfs_item_key_to_cpu(eb, &key, i);
  
  		if (key.type != BTRFS_EXTENT_DATA_KEY)
  			continue;
  
  		fi = btrfs_item_ptr(eb, i, struct btrfs_file_extent_item);
  		/* filter out non qgroup-accountable extents  */
  		extent_type = btrfs_file_extent_type(eb, fi);
  
  		if (extent_type == BTRFS_FILE_EXTENT_INLINE)
  			continue;
  
  		bytenr = btrfs_file_extent_disk_bytenr(eb, fi);
  		if (!bytenr)
  			continue;
  
  		num_bytes = btrfs_file_extent_disk_num_bytes(eb, fi);

  		ret = btrfs_qgroup_trace_extent(trans, bytenr, num_bytes,
  						GFP_NOFS);

  		if (ret)
  			return ret;
  	}

  	cond_resched();

  	return 0;
  }
  
  /*
   * Walk up the tree from the bottom, freeing leaves and any interior
   * nodes which have had all slots visited. If a node (leaf or
   * interior) is freed, the node above it will have it's slot
   * incremented. The root node will never be freed.
   *
   * At the end of this function, we should have a path which has all
   * slots incremented to the next position for a search. If we need to
   * read a new node it will be NULL and the node above it will have the
   * correct slot selected for a later read.
   *
   * If we increment the root nodes slot counter past the number of
   * elements, 1 is returned to signal completion of the search.
   */

  static int adjust_slots_upwards(struct btrfs_path *path, int root_level)

  {
  	int level = 0;
  	int nr, slot;
  	struct extent_buffer *eb;
  
  	if (root_level == 0)
  		return 1;
  
  	while (level <= root_level) {
  		eb = path->nodes[level];
  		nr = btrfs_header_nritems(eb);
  		path->slots[level]++;
  		slot = path->slots[level];
  		if (slot >= nr || level == 0) {
  			/*
  			 * Don't free the root -  we will detect this
  			 * condition after our loop and return a
  			 * positive value for caller to stop walking the tree.
  			 */
  			if (level != root_level) {
  				btrfs_tree_unlock_rw(eb, path->locks[level]);
  				path->locks[level] = 0;
  
  				free_extent_buffer(eb);
  				path->nodes[level] = NULL;
  				path->slots[level] = 0;
  			}
  		} else {
  			/*
  			 * We have a valid slot to walk back down
  			 * from. Stop here so caller can process these
  			 * new nodes.
  			 */
  			break;
  		}
  
  		level++;
  	}
  
  	eb = path->nodes[root_level];
  	if (path->slots[root_level] >= btrfs_header_nritems(eb))
  		return 1;
  
  	return 0;
  }

  /*
   * Helper function to trace a subtree tree block swap.
   *
   * The swap will happen in highest tree block, but there may be a lot of
   * tree blocks involved.
   *
   * For example:
   *  OO = Old tree blocks
   *  NN = New tree blocks allocated during balance
   *
   *           File tree (257)                  Reloc tree for 257
   * L2              OO                                NN
   *               /    \                            /    \
   * L1          OO      OO (a)                    OO      NN (a)
   *            / \     / \                       / \     / \
   * L0       OO   OO OO   OO                   OO   OO NN   NN
   *                  (b)  (c)                          (b)  (c)
   *
   * When calling qgroup_trace_extent_swap(), we will pass:
   * @src_eb = OO(a)
   * @dst_path = [ nodes[1] = NN(a), nodes[0] = NN(c) ]
   * @dst_level = 0
   * @root_level = 1
   *
   * In that case, qgroup_trace_extent_swap() will search from OO(a) to
   * reach OO(c), then mark both OO(c) and NN(c) as qgroup dirty.
   *
   * The main work of qgroup_trace_extent_swap() can be split into 3 parts:
   *
   * 1) Tree search from @src_eb
   *    It should acts as a simplified btrfs_search_slot().
   *    The key for search can be extracted from @dst_path->nodes[dst_level]
   *    (first key).
   *
   * 2) Mark the final tree blocks in @src_path and @dst_path qgroup dirty
   *    NOTE: In above case, OO(a) and NN(a) won't be marked qgroup dirty.

   *    They should be marked during previous (@dst_level = 1) iteration.

   *
   * 3) Mark file extents in leaves dirty
   *    We don't have good way to pick out new file extents only.
   *    So we still follow the old method by scanning all file extents in
   *    the leave.
   *

   * This function can free us from keeping two paths, thus later we only need

   * to care about how to iterate all new tree blocks in reloc tree.
   */
  static int qgroup_trace_extent_swap(struct btrfs_trans_handle* trans,
  				    struct extent_buffer *src_eb,
  				    struct btrfs_path *dst_path,

  				    int dst_level, int root_level,
  				    bool trace_leaf)

  {
  	struct btrfs_key key;
  	struct btrfs_path *src_path;
  	struct btrfs_fs_info *fs_info = trans->fs_info;
  	u32 nodesize = fs_info->nodesize;
  	int cur_level = root_level;
  	int ret;
  
  	BUG_ON(dst_level > root_level);
  	/* Level mismatch */
  	if (btrfs_header_level(src_eb) != root_level)
  		return -EINVAL;
  
  	src_path = btrfs_alloc_path();
  	if (!src_path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	if (dst_level)
  		btrfs_node_key_to_cpu(dst_path->nodes[dst_level], &key, 0);
  	else
  		btrfs_item_key_to_cpu(dst_path->nodes[dst_level], &key, 0);
  
  	/* For src_path */

  	atomic_inc(&src_eb->refs);

  	src_path->nodes[root_level] = src_eb;
  	src_path->slots[root_level] = dst_path->slots[root_level];
  	src_path->locks[root_level] = 0;
  
  	/* A simplified version of btrfs_search_slot() */
  	while (cur_level >= dst_level) {
  		struct btrfs_key src_key;
  		struct btrfs_key dst_key;
  
  		if (src_path->nodes[cur_level] == NULL) {
  			struct btrfs_key first_key;
  			struct extent_buffer *eb;
  			int parent_slot;
  			u64 child_gen;
  			u64 child_bytenr;
  
  			eb = src_path->nodes[cur_level + 1];
  			parent_slot = src_path->slots[cur_level + 1];
  			child_bytenr = btrfs_node_blockptr(eb, parent_slot);
  			child_gen = btrfs_node_ptr_generation(eb, parent_slot);
  			btrfs_node_key_to_cpu(eb, &first_key, parent_slot);
  
  			eb = read_tree_block(fs_info, child_bytenr, child_gen,
  					     cur_level, &first_key);
  			if (IS_ERR(eb)) {
  				ret = PTR_ERR(eb);
  				goto out;
  			} else if (!extent_buffer_uptodate(eb)) {
  				free_extent_buffer(eb);
  				ret = -EIO;
  				goto out;
  			}
  
  			src_path->nodes[cur_level] = eb;
  
  			btrfs_tree_read_lock(eb);

  			btrfs_set_lock_blocking_read(eb);

  			src_path->locks[cur_level] = BTRFS_READ_LOCK_BLOCKING;
  		}
  
  		src_path->slots[cur_level] = dst_path->slots[cur_level];
  		if (cur_level) {
  			btrfs_node_key_to_cpu(dst_path->nodes[cur_level],
  					&dst_key, dst_path->slots[cur_level]);
  			btrfs_node_key_to_cpu(src_path->nodes[cur_level],
  					&src_key, src_path->slots[cur_level]);
  		} else {
  			btrfs_item_key_to_cpu(dst_path->nodes[cur_level],
  					&dst_key, dst_path->slots[cur_level]);
  			btrfs_item_key_to_cpu(src_path->nodes[cur_level],
  					&src_key, src_path->slots[cur_level]);
  		}
  		/* Content mismatch, something went wrong */
  		if (btrfs_comp_cpu_keys(&dst_key, &src_key)) {
  			ret = -ENOENT;
  			goto out;
  		}
  		cur_level--;
  	}
  
  	/*
  	 * Now both @dst_path and @src_path have been populated, record the tree
  	 * blocks for qgroup accounting.
  	 */
  	ret = btrfs_qgroup_trace_extent(trans, src_path->nodes[dst_level]->start,
  			nodesize, GFP_NOFS);
  	if (ret < 0)
  		goto out;
  	ret = btrfs_qgroup_trace_extent(trans,
  			dst_path->nodes[dst_level]->start,
  			nodesize, GFP_NOFS);
  	if (ret < 0)
  		goto out;
  
  	/* Record leaf file extents */

  	if (dst_level == 0 && trace_leaf) {

  		ret = btrfs_qgroup_trace_leaf_items(trans, src_path->nodes[0]);
  		if (ret < 0)
  			goto out;
  		ret = btrfs_qgroup_trace_leaf_items(trans, dst_path->nodes[0]);
  	}
  out:
  	btrfs_free_path(src_path);
  	return ret;
  }

  /*
   * Helper function to do recursive generation-aware depth-first search, to
   * locate all new tree blocks in a subtree of reloc tree.
   *
   * E.g. (OO = Old tree blocks, NN = New tree blocks, whose gen == last_snapshot)
   *         reloc tree
   * L2         NN (a)
   *          /    \
   * L1    OO        NN (b)
   *      /  \      /  \
   * L0  OO  OO    OO  NN
   *               (c) (d)
   * If we pass:
   * @dst_path = [ nodes[1] = NN(b), nodes[0] = NULL ],
   * @cur_level = 1
   * @root_level = 1
   *
   * We will iterate through tree blocks NN(b), NN(d) and info qgroup to trace
   * above tree blocks along with their counter parts in file tree.

   * While during search, old tree blocks OO(c) will be skipped as tree block swap

   * won't affect OO(c).
   */
  static int qgroup_trace_new_subtree_blocks(struct btrfs_trans_handle* trans,
  					   struct extent_buffer *src_eb,
  					   struct btrfs_path *dst_path,
  					   int cur_level, int root_level,

  					   u64 last_snapshot, bool trace_leaf)

  {
  	struct btrfs_fs_info *fs_info = trans->fs_info;
  	struct extent_buffer *eb;
  	bool need_cleanup = false;
  	int ret = 0;
  	int i;
  
  	/* Level sanity check */

  	if (cur_level < 0 || cur_level >= BTRFS_MAX_LEVEL - 1 ||
  	    root_level < 0 || root_level >= BTRFS_MAX_LEVEL - 1 ||

  	    root_level < cur_level) {
  		btrfs_err_rl(fs_info,
  			"%s: bad levels, cur_level=%d root_level=%d",
  			__func__, cur_level, root_level);
  		return -EUCLEAN;
  	}
  
  	/* Read the tree block if needed */
  	if (dst_path->nodes[cur_level] == NULL) {
  		struct btrfs_key first_key;
  		int parent_slot;
  		u64 child_gen;
  		u64 child_bytenr;
  
  		/*
  		 * dst_path->nodes[root_level] must be initialized before
  		 * calling this function.
  		 */
  		if (cur_level == root_level) {
  			btrfs_err_rl(fs_info,
  	"%s: dst_path->nodes[%d] not initialized, root_level=%d cur_level=%d",
  				__func__, root_level, root_level, cur_level);
  			return -EUCLEAN;
  		}
  
  		/*
  		 * We need to get child blockptr/gen from parent before we can
  		 * read it.
  		  */
  		eb = dst_path->nodes[cur_level + 1];
  		parent_slot = dst_path->slots[cur_level + 1];
  		child_bytenr = btrfs_node_blockptr(eb, parent_slot);
  		child_gen = btrfs_node_ptr_generation(eb, parent_slot);
  		btrfs_node_key_to_cpu(eb, &first_key, parent_slot);
  
  		/* This node is old, no need to trace */
  		if (child_gen < last_snapshot)
  			goto out;
  
  		eb = read_tree_block(fs_info, child_bytenr, child_gen,
  				     cur_level, &first_key);
  		if (IS_ERR(eb)) {
  			ret = PTR_ERR(eb);
  			goto out;
  		} else if (!extent_buffer_uptodate(eb)) {
  			free_extent_buffer(eb);
  			ret = -EIO;
  			goto out;
  		}
  
  		dst_path->nodes[cur_level] = eb;
  		dst_path->slots[cur_level] = 0;
  
  		btrfs_tree_read_lock(eb);

  		btrfs_set_lock_blocking_read(eb);

  		dst_path->locks[cur_level] = BTRFS_READ_LOCK_BLOCKING;
  		need_cleanup = true;
  	}
  
  	/* Now record this tree block and its counter part for qgroups */
  	ret = qgroup_trace_extent_swap(trans, src_eb, dst_path, cur_level,

  				       root_level, trace_leaf);

  	if (ret < 0)
  		goto cleanup;
  
  	eb = dst_path->nodes[cur_level];
  
  	if (cur_level > 0) {
  		/* Iterate all child tree blocks */
  		for (i = 0; i < btrfs_header_nritems(eb); i++) {
  			/* Skip old tree blocks as they won't be swapped */
  			if (btrfs_node_ptr_generation(eb, i) < last_snapshot)
  				continue;
  			dst_path->slots[cur_level] = i;
  
  			/* Recursive call (at most 7 times) */
  			ret = qgroup_trace_new_subtree_blocks(trans, src_eb,
  					dst_path, cur_level - 1, root_level,

  					last_snapshot, trace_leaf);

  			if (ret < 0)
  				goto cleanup;
  		}
  	}
  
  cleanup:
  	if (need_cleanup) {
  		/* Clean up */
  		btrfs_tree_unlock_rw(dst_path->nodes[cur_level],
  				     dst_path->locks[cur_level]);
  		free_extent_buffer(dst_path->nodes[cur_level]);
  		dst_path->nodes[cur_level] = NULL;
  		dst_path->slots[cur_level] = 0;
  		dst_path->locks[cur_level] = 0;
  	}
  out:
  	return ret;
  }

  static int qgroup_trace_subtree_swap(struct btrfs_trans_handle *trans,
  				struct extent_buffer *src_eb,
  				struct extent_buffer *dst_eb,
  				u64 last_snapshot, bool trace_leaf)
  {
  	struct btrfs_fs_info *fs_info = trans->fs_info;
  	struct btrfs_path *dst_path = NULL;
  	int level;
  	int ret;
  
  	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
  		return 0;
  
  	/* Wrong parameter order */
  	if (btrfs_header_generation(src_eb) > btrfs_header_generation(dst_eb)) {
  		btrfs_err_rl(fs_info,
  		"%s: bad parameter order, src_gen=%llu dst_gen=%llu", __func__,
  			     btrfs_header_generation(src_eb),
  			     btrfs_header_generation(dst_eb));
  		return -EUCLEAN;
  	}
  
  	if (!extent_buffer_uptodate(src_eb) || !extent_buffer_uptodate(dst_eb)) {
  		ret = -EIO;
  		goto out;
  	}
  
  	level = btrfs_header_level(dst_eb);
  	dst_path = btrfs_alloc_path();
  	if (!dst_path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  	/* For dst_path */

  	atomic_inc(&dst_eb->refs);

  	dst_path->nodes[level] = dst_eb;
  	dst_path->slots[level] = 0;
  	dst_path->locks[level] = 0;
  
  	/* Do the generation aware breadth-first search */
  	ret = qgroup_trace_new_subtree_blocks(trans, src_eb, dst_path, level,
  					      level, last_snapshot, trace_leaf);
  	if (ret < 0)
  		goto out;
  	ret = 0;
  
  out:
  	btrfs_free_path(dst_path);
  	if (ret < 0)
  		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
  	return ret;
  }

  int btrfs_qgroup_trace_subtree(struct btrfs_trans_handle *trans,

  			       struct extent_buffer *root_eb,
  			       u64 root_gen, int root_level)
  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	int ret = 0;
  	int level;
  	struct extent_buffer *eb = root_eb;
  	struct btrfs_path *path = NULL;

  	BUG_ON(root_level < 0 || root_level >= BTRFS_MAX_LEVEL);

  	BUG_ON(root_eb == NULL);

  	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))

  		return 0;
  
  	if (!extent_buffer_uptodate(root_eb)) {

  		ret = btrfs_read_buffer(root_eb, root_gen, root_level, NULL);

  		if (ret)
  			goto out;
  	}
  
  	if (root_level == 0) {

  		ret = btrfs_qgroup_trace_leaf_items(trans, root_eb);

  		goto out;
  	}
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	/*
  	 * Walk down the tree.  Missing extent blocks are filled in as
  	 * we go. Metadata is accounted every time we read a new
  	 * extent block.
  	 *
  	 * When we reach a leaf, we account for file extent items in it,
  	 * walk back up the tree (adjusting slot pointers as we go)
  	 * and restart the search process.
  	 */

  	atomic_inc(&root_eb->refs);	/* For path */

  	path->nodes[root_level] = root_eb;
  	path->slots[root_level] = 0;
  	path->locks[root_level] = 0; /* so release_path doesn't try to unlock */
  walk_down:
  	level = root_level;
  	while (level >= 0) {
  		if (path->nodes[level] == NULL) {

  			struct btrfs_key first_key;

  			int parent_slot;
  			u64 child_gen;
  			u64 child_bytenr;
  
  			/*
  			 * We need to get child blockptr/gen from parent before
  			 * we can read it.
  			  */
  			eb = path->nodes[level + 1];
  			parent_slot = path->slots[level + 1];
  			child_bytenr = btrfs_node_blockptr(eb, parent_slot);
  			child_gen = btrfs_node_ptr_generation(eb, parent_slot);

  			btrfs_node_key_to_cpu(eb, &first_key, parent_slot);

  			eb = read_tree_block(fs_info, child_bytenr, child_gen,
  					     level, &first_key);

  			if (IS_ERR(eb)) {
  				ret = PTR_ERR(eb);
  				goto out;
  			} else if (!extent_buffer_uptodate(eb)) {
  				free_extent_buffer(eb);
  				ret = -EIO;
  				goto out;
  			}
  
  			path->nodes[level] = eb;
  			path->slots[level] = 0;
  
  			btrfs_tree_read_lock(eb);

  			btrfs_set_lock_blocking_read(eb);

  			path->locks[level] = BTRFS_READ_LOCK_BLOCKING;

  			ret = btrfs_qgroup_trace_extent(trans, child_bytenr,

  							fs_info->nodesize,
  							GFP_NOFS);

  			if (ret)
  				goto out;
  		}
  
  		if (level == 0) {

  			ret = btrfs_qgroup_trace_leaf_items(trans,
  							    path->nodes[level]);

  			if (ret)
  				goto out;
  
  			/* Nonzero return here means we completed our search */

  			ret = adjust_slots_upwards(path, root_level);

  			if (ret)
  				break;
  
  			/* Restart search with new slots */
  			goto walk_down;
  		}
  
  		level--;
  	}
  
  	ret = 0;
  out:
  	btrfs_free_path(path);
  
  	return ret;
  }

  #define UPDATE_NEW	0
  #define UPDATE_OLD	1
  /*
   * Walk all of the roots that points to the bytenr and adjust their refcnts.
   */
  static int qgroup_update_refcnt(struct btrfs_fs_info *fs_info,
  				struct ulist *roots, struct ulist *tmp,
  				struct ulist *qgroups, u64 seq, int update_old)
  {
  	struct ulist_node *unode;
  	struct ulist_iterator uiter;
  	struct ulist_node *tmp_unode;
  	struct ulist_iterator tmp_uiter;
  	struct btrfs_qgroup *qg;
  	int ret = 0;
  
  	if (!roots)
  		return 0;
  	ULIST_ITER_INIT(&uiter);
  	while ((unode = ulist_next(roots, &uiter))) {
  		qg = find_qgroup_rb(fs_info, unode->val);
  		if (!qg)
  			continue;
  
  		ulist_reinit(tmp);

  		ret = ulist_add(qgroups, qg->qgroupid, qgroup_to_aux(qg),

  				GFP_ATOMIC);
  		if (ret < 0)
  			return ret;

  		ret = ulist_add(tmp, qg->qgroupid, qgroup_to_aux(qg), GFP_ATOMIC);

  		if (ret < 0)
  			return ret;
  		ULIST_ITER_INIT(&tmp_uiter);
  		while ((tmp_unode = ulist_next(tmp, &tmp_uiter))) {
  			struct btrfs_qgroup_list *glist;

  			qg = unode_aux_to_qgroup(tmp_unode);

  			if (update_old)
  				btrfs_qgroup_update_old_refcnt(qg, seq, 1);
  			else
  				btrfs_qgroup_update_new_refcnt(qg, seq, 1);
  			list_for_each_entry(glist, &qg->groups, next_group) {
  				ret = ulist_add(qgroups, glist->group->qgroupid,

  						qgroup_to_aux(glist->group),

  						GFP_ATOMIC);
  				if (ret < 0)
  					return ret;
  				ret = ulist_add(tmp, glist->group->qgroupid,

  						qgroup_to_aux(glist->group),

  						GFP_ATOMIC);
  				if (ret < 0)
  					return ret;
  			}
  		}
  	}
  	return 0;
  }

  /*

   * Update qgroup rfer/excl counters.
   * Rfer update is easy, codes can explain themselves.

   *

   * Excl update is tricky, the update is split into 2 part.
   * Part 1: Possible exclusive <-> sharing detect:
   *	|	A	|	!A	|
   *  -------------------------------------
   *  B	|	*	|	-	|
   *  -------------------------------------
   *  !B	|	+	|	**	|
   *  -------------------------------------
   *
   * Conditions:
   * A:	cur_old_roots < nr_old_roots	(not exclusive before)
   * !A:	cur_old_roots == nr_old_roots	(possible exclusive before)
   * B:	cur_new_roots < nr_new_roots	(not exclusive now)

   * !B:	cur_new_roots == nr_new_roots	(possible exclusive now)

   *
   * Results:
   * +: Possible sharing -> exclusive	-: Possible exclusive -> sharing
   * *: Definitely not changed.		**: Possible unchanged.
   *
   * For !A and !B condition, the exception is cur_old/new_roots == 0 case.
   *
   * To make the logic clear, we first use condition A and B to split
   * combination into 4 results.
   *
   * Then, for result "+" and "-", check old/new_roots == 0 case, as in them
   * only on variant maybe 0.
   *
   * Lastly, check result **, since there are 2 variants maybe 0, split them
   * again(2x2).
   * But this time we don't need to consider other things, the codes and logic
   * is easy to understand now.
   */
  static int qgroup_update_counters(struct btrfs_fs_info *fs_info,
  				  struct ulist *qgroups,
  				  u64 nr_old_roots,
  				  u64 nr_new_roots,
  				  u64 num_bytes, u64 seq)
  {
  	struct ulist_node *unode;
  	struct ulist_iterator uiter;
  	struct btrfs_qgroup *qg;
  	u64 cur_new_count, cur_old_count;
  
  	ULIST_ITER_INIT(&uiter);
  	while ((unode = ulist_next(qgroups, &uiter))) {
  		bool dirty = false;

  		qg = unode_aux_to_qgroup(unode);

  		cur_old_count = btrfs_qgroup_get_old_refcnt(qg, seq);
  		cur_new_count = btrfs_qgroup_get_new_refcnt(qg, seq);

  		trace_qgroup_update_counters(fs_info, qg, cur_old_count,
  					     cur_new_count);

  		/* Rfer update part */
  		if (cur_old_count == 0 && cur_new_count > 0) {
  			qg->rfer += num_bytes;
  			qg->rfer_cmpr += num_bytes;
  			dirty = true;
  		}
  		if (cur_old_count > 0 && cur_new_count == 0) {
  			qg->rfer -= num_bytes;
  			qg->rfer_cmpr -= num_bytes;
  			dirty = true;
  		}
  
  		/* Excl update part */
  		/* Exclusive/none -> shared case */
  		if (cur_old_count == nr_old_roots &&
  		    cur_new_count < nr_new_roots) {
  			/* Exclusive -> shared */
  			if (cur_old_count != 0) {
  				qg->excl -= num_bytes;
  				qg->excl_cmpr -= num_bytes;
  				dirty = true;
  			}
  		}
  
  		/* Shared -> exclusive/none case */
  		if (cur_old_count < nr_old_roots &&
  		    cur_new_count == nr_new_roots) {
  			/* Shared->exclusive */
  			if (cur_new_count != 0) {
  				qg->excl += num_bytes;
  				qg->excl_cmpr += num_bytes;
  				dirty = true;
  			}
  		}
  
  		/* Exclusive/none -> exclusive/none case */
  		if (cur_old_count == nr_old_roots &&
  		    cur_new_count == nr_new_roots) {
  			if (cur_old_count == 0) {
  				/* None -> exclusive/none */
  
  				if (cur_new_count != 0) {
  					/* None -> exclusive */
  					qg->excl += num_bytes;
  					qg->excl_cmpr += num_bytes;
  					dirty = true;
  				}
  				/* None -> none, nothing changed */
  			} else {
  				/* Exclusive -> exclusive/none */
  
  				if (cur_new_count == 0) {
  					/* Exclusive -> none */
  					qg->excl -= num_bytes;
  					qg->excl_cmpr -= num_bytes;
  					dirty = true;
  				}
  				/* Exclusive -> exclusive, nothing changed */
  			}
  		}

  		if (dirty)
  			qgroup_dirty(fs_info, qg);
  	}
  	return 0;
  }

  /*
   * Check if the @roots potentially is a list of fs tree roots
   *
   * Return 0 for definitely not a fs/subvol tree roots ulist
   * Return 1 for possible fs/subvol tree roots in the list (considering an empty
   *          one as well)
   */
  static int maybe_fs_roots(struct ulist *roots)
  {
  	struct ulist_node *unode;
  	struct ulist_iterator uiter;
  
  	/* Empty one, still possible for fs roots */
  	if (!roots || roots->nnodes == 0)
  		return 1;
  
  	ULIST_ITER_INIT(&uiter);
  	unode = ulist_next(roots, &uiter);
  	if (!unode)
  		return 1;
  
  	/*
  	 * If it contains fs tree roots, then it must belong to fs/subvol
  	 * trees.
  	 * If it contains a non-fs tree, it won't be shared with fs/subvol trees.
  	 */
  	return is_fstree(unode->val);
  }

  int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
  				u64 num_bytes, struct ulist *old_roots,
  				struct ulist *new_roots)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct ulist *qgroups = NULL;
  	struct ulist *tmp = NULL;
  	u64 seq;
  	u64 nr_new_roots = 0;
  	u64 nr_old_roots = 0;
  	int ret = 0;

  	/*
  	 * If quotas get disabled meanwhile, the resouces need to be freed and
  	 * we can't just exit here.
  	 */

  	if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))

  		goto out_free;

  	if (new_roots) {
  		if (!maybe_fs_roots(new_roots))
  			goto out_free;

  		nr_new_roots = new_roots->nnodes;

  	}
  	if (old_roots) {
  		if (!maybe_fs_roots(old_roots))
  			goto out_free;

  		nr_old_roots = old_roots->nnodes;

  	}
  
  	/* Quick exit, either not fs tree roots, or won't affect any qgroup */
  	if (nr_old_roots == 0 && nr_new_roots == 0)
  		goto out_free;

  	BUG_ON(!fs_info->quota_root);

  	trace_btrfs_qgroup_account_extent(fs_info, trans->transid, bytenr,
  					num_bytes, nr_old_roots, nr_new_roots);

  	qgroups = ulist_alloc(GFP_NOFS);
  	if (!qgroups) {
  		ret = -ENOMEM;
  		goto out_free;
  	}
  	tmp = ulist_alloc(GFP_NOFS);
  	if (!tmp) {
  		ret = -ENOMEM;
  		goto out_free;
  	}
  
  	mutex_lock(&fs_info->qgroup_rescan_lock);
  	if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
  		if (fs_info->qgroup_rescan_progress.objectid <= bytenr) {
  			mutex_unlock(&fs_info->qgroup_rescan_lock);
  			ret = 0;
  			goto out_free;
  		}
  	}
  	mutex_unlock(&fs_info->qgroup_rescan_lock);
  
  	spin_lock(&fs_info->qgroup_lock);
  	seq = fs_info->qgroup_seq;
  
  	/* Update old refcnts using old_roots */
  	ret = qgroup_update_refcnt(fs_info, old_roots, tmp, qgroups, seq,
  				   UPDATE_OLD);
  	if (ret < 0)
  		goto out;
  
  	/* Update new refcnts using new_roots */
  	ret = qgroup_update_refcnt(fs_info, new_roots, tmp, qgroups, seq,
  				   UPDATE_NEW);
  	if (ret < 0)
  		goto out;
  
  	qgroup_update_counters(fs_info, qgroups, nr_old_roots, nr_new_roots,
  			       num_bytes, seq);
  
  	/*
  	 * Bump qgroup_seq to avoid seq overlap
  	 */
  	fs_info->qgroup_seq += max(nr_old_roots, nr_new_roots) + 1;
  out:
  	spin_unlock(&fs_info->qgroup_lock);
  out_free:
  	ulist_free(tmp);
  	ulist_free(qgroups);
  	ulist_free(old_roots);
  	ulist_free(new_roots);
  	return ret;
  }

  int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_qgroup_extent_record *record;
  	struct btrfs_delayed_ref_root *delayed_refs;
  	struct ulist *new_roots = NULL;
  	struct rb_node *node;

  	u64 num_dirty_extents = 0;

  	u64 qgroup_to_skip;

  	int ret = 0;
  
  	delayed_refs = &trans->transaction->delayed_refs;

  	qgroup_to_skip = delayed_refs->qgroup_to_skip;

  	while ((node = rb_first(&delayed_refs->dirty_extent_root))) {
  		record = rb_entry(node, struct btrfs_qgroup_extent_record,
  				  node);

  		num_dirty_extents++;

  		trace_btrfs_qgroup_account_extents(fs_info, record);

  		if (!ret) {
  			/*

  			 * Old roots should be searched when inserting qgroup
  			 * extent record
  			 */
  			if (WARN_ON(!record->old_roots)) {
  				/* Search commit root to find old_roots */
  				ret = btrfs_find_all_roots(NULL, fs_info,
  						record->bytenr, 0,

  						&record->old_roots, false);

  				if (ret < 0)
  					goto cleanup;
  			}

  			/* Free the reserved data space */
  			btrfs_qgroup_free_refroot(fs_info,
  					record->data_rsv_refroot,
  					record->data_rsv,
  					BTRFS_QGROUP_RSV_DATA);

  			/*

  			 * Use SEQ_LAST as time_seq to do special search, which

  			 * doesn't lock tree or delayed_refs and search current
  			 * root. It's safe inside commit_transaction().
  			 */
  			ret = btrfs_find_all_roots(trans, fs_info,

  				record->bytenr, SEQ_LAST, &new_roots, false);

  			if (ret < 0)
  				goto cleanup;

  			if (qgroup_to_skip) {

  				ulist_del(new_roots, qgroup_to_skip, 0);

  				ulist_del(record->old_roots, qgroup_to_skip,
  					  0);
  			}

  			ret = btrfs_qgroup_account_extent(trans, record->bytenr,
  							  record->num_bytes,
  							  record->old_roots,
  							  new_roots);

  			record->old_roots = NULL;
  			new_roots = NULL;
  		}
  cleanup:
  		ulist_free(record->old_roots);
  		ulist_free(new_roots);
  		new_roots = NULL;
  		rb_erase(node, &delayed_refs->dirty_extent_root);
  		kfree(record);
  
  	}

  	trace_qgroup_num_dirty_extents(fs_info, trans->transid,
  				       num_dirty_extents);

  	return ret;
  }

  /*

   * called from commit_transaction. Writes all changed qgroups to disk.
   */

  int btrfs_run_qgroups(struct btrfs_trans_handle *trans)

  {

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	int ret = 0;

  	if (!fs_info->quota_root)

  		return ret;

  
  	spin_lock(&fs_info->qgroup_lock);
  	while (!list_empty(&fs_info->dirty_qgroups)) {
  		struct btrfs_qgroup *qgroup;
  		qgroup = list_first_entry(&fs_info->dirty_qgroups,
  					  struct btrfs_qgroup, dirty);
  		list_del_init(&qgroup->dirty);
  		spin_unlock(&fs_info->qgroup_lock);

  		ret = update_qgroup_info_item(trans, qgroup);

  		if (ret)
  			fs_info->qgroup_flags |=

  					BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;

  		ret = update_qgroup_limit_item(trans, qgroup);

  		if (ret)
  			fs_info->qgroup_flags |=

  					BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
  		spin_lock(&fs_info->qgroup_lock);
  	}

  	if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))

  		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_ON;
  	else
  		fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_ON;
  	spin_unlock(&fs_info->qgroup_lock);

  	ret = update_qgroup_status_item(trans);

  	if (ret)
  		fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;

  	return ret;
  }
  
  /*

   * Copy the accounting information between qgroups. This is necessary

   * when a snapshot or a subvolume is created. Throwing an error will
   * cause a transaction abort so we take extra care here to only error
   * when a readonly fs is a reasonable outcome.

   */

  int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
  			 u64 objectid, struct btrfs_qgroup_inherit *inherit)

  {
  	int ret = 0;
  	int i;
  	u64 *i_qgroups;

  	bool committing = false;

  	struct btrfs_fs_info *fs_info = trans->fs_info;

  	struct btrfs_root *quota_root;

  	struct btrfs_qgroup *srcgroup;
  	struct btrfs_qgroup *dstgroup;

  	bool need_rescan = false;

  	u32 level_size = 0;

  	u64 nums;