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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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 <linux/sched/mm.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"
 #include "tree-mod-log.h"
 
 /*
  * 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;
 
     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);
     }
 }
 
 /* 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;
 }
 
 /*
  * Add relation specified by two qgroups.
  *
  * Must be called with qgroup_lock held.
  *
  * Return: 0        on success
  *         -ENOENT  if one of the qgroups is NULL
  *         <0       other errors
  */
 static int __add_relation_rb(struct btrfs_qgroup *member, struct btrfs_qgroup *parent)
 {
     struct btrfs_qgroup_list *list;
 
     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;
 }
 
 /*
  * Add relation specified by two qgoup ids.
  *
  * Must be called with qgroup_lock held.
  *
  * Return: 0        on success
  *         -ENOENT  if one of the ids does not exist
  *         <0       other errors
  */
 static int add_relation_rb(struct btrfs_fs_info *fs_info, u64 memberid, u64 parentid)
 {
     struct btrfs_qgroup *member;
     struct btrfs_qgroup *parent;
 
     member = find_qgroup_rb(fs_info, memberid);
     parent = find_qgroup_rb(fs_info, parentid);
 
     return __add_relation_rb(member, parent);
 }
 
 /* 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:
     btrfs_free_path(path);
     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);
 
     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);
         btrfs_sysfs_del_one_qgroup(fs_info, qgroup);
         kfree(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;
 
     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;
     struct ulist *ulist = NULL;
     int ret = 0;
     int slot;
 
     /*
      * We need to have subvol_sem write locked, to prevent races between
      * concurrent tasks trying to enable quotas, because we will unlock
      * and relock qgroup_ioctl_lock before setting fs_info->quota_root
      * and before setting BTRFS_FS_QUOTA_ENABLED.
      */
     lockdep_assert_held_write(&fs_info->subvol_sem);
 
     if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
         btrfs_err(fs_info,
               "qgroups are currently unsupported in extent tree v2");
         return -EINVAL;
     }
 
     mutex_lock(&fs_info->qgroup_ioctl_lock);
     if (fs_info->quota_root)
         goto out;
 
     ulist = ulist_alloc(GFP_KERNEL);
     if (!ulist) {
         ret = -ENOMEM;
         goto out;
     }
 
     ret = btrfs_sysfs_add_qgroups(fs_info);
     if (ret < 0)
         goto out;
 
     /*
      * Unlock qgroup_ioctl_lock before starting the transaction. This is to
      * avoid lock acquisition inversion problems (reported by lockdep) between
      * qgroup_ioctl_lock and the vfs freeze semaphores, acquired when we
      * start a transaction.
      * After we started the transaction lock qgroup_ioctl_lock again and
      * check if someone else created the quota root in the meanwhile. If so,
      * just return success and release the transaction handle.
      *
      * Also we don't need to worry about someone else calling
      * btrfs_sysfs_add_qgroups() after we unlock and getting an error because
      * that function returns 0 (success) when the sysfs entries already exist.
      */
     mutex_unlock(&fs_info->qgroup_ioctl_lock);
 
     /*
      * 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);
 
     mutex_lock(&fs_info->qgroup_ioctl_lock);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         trans = NULL;
         goto out;
     }
 
     if (fs_info->quota_root)
         goto out;
 
     fs_info->qgroup_ulist = ulist;
     ulist = NULL;
 
     /*
      * 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) {
 
             /* Release locks on tree_root before we access quota_root */
             btrfs_release_path(path);
 
             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_search_slot_for_read(tree_root, &found_key,
                              path, 1, 0);
             if (ret < 0) {
                 btrfs_abort_transaction(trans, ret);
                 goto out_free_path;
             }
             if (ret > 0) {
                 /*
                  * Shouldn't happen, but in case it does we
                  * don't need to do the btrfs_next_item, just
                  * continue.
                  */
                 continue;
             }
         }
         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;
     }
 
     mutex_unlock(&fs_info->qgroup_ioctl_lock);
     /*
      * Commit the transaction while not holding qgroup_ioctl_lock, to avoid
      * a deadlock with tasks concurrently doing other qgroup operations, such
      * adding/removing qgroups or adding/deleting qgroup relations for example,
      * because all qgroup operations first start or join a transaction and then
      * lock the qgroup_ioctl_lock mutex.
      * We are safe from a concurrent task trying to enable quotas, by calling
      * this function, since we are serialized by fs_info->subvol_sem.
      */
     ret = btrfs_commit_transaction(trans);
     trans = NULL;
     mutex_lock(&fs_info->qgroup_ioctl_lock);
     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;
         btrfs_sysfs_del_qgroups(fs_info);
     }
     mutex_unlock(&fs_info->qgroup_ioctl_lock);
     if (ret && trans)
         btrfs_end_transaction(trans);
     else if (trans)
         ret = btrfs_end_transaction(trans);
     ulist_free(ulist);
     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;
 
     /*
      * We need to have subvol_sem write locked, to prevent races between
      * concurrent tasks trying to disable quotas, because we will unlock
      * and relock qgroup_ioctl_lock across BTRFS_FS_QUOTA_ENABLED changes.
      */
     lockdep_assert_held_write(&fs_info->subvol_sem);
 
     mutex_lock(&fs_info->qgroup_ioctl_lock);
     if (!fs_info->quota_root)
         goto out;
 
     /*
      * Unlock the qgroup_ioctl_lock mutex before waiting for the rescan worker to
      * complete. Otherwise we can deadlock because btrfs_remove_qgroup() needs
      * to lock that mutex while holding a transaction handle and the rescan
      * worker needs to commit a transaction.
      */
     mutex_unlock(&fs_info->qgroup_ioctl_lock);
 
     /*
      * Request qgroup rescan worker to complete and wait for it. This wait
      * must be done before transaction start for quota disable since it may
      * deadlock with transaction by the qgroup rescan worker.
      */
     clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
     btrfs_qgroup_wait_for_completion(fs_info, false);
 
     /*
      * 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.
      *
      * Also, we must always start a transaction without holding the mutex
      * qgroup_ioctl_lock, see btrfs_quota_enable().
      */
     trans = btrfs_start_transaction(fs_info->tree_root, 1);
 
     mutex_lock(&fs_info->qgroup_ioctl_lock);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         trans = NULL;
         set_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
         goto out;
     }
 
     if (!fs_info->quota_root)
         goto out;
 
     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 out;
     }
 
     ret = btrfs_del_root(trans, &quota_root->root_key);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     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, btrfs_root_id(quota_root),
                   quota_root->node, 0, 1);
 
     btrfs_put_root(quota_root);
 
 out:
     mutex_unlock(&fs_info->qgroup_ioctl_lock);
     if (ret && trans)
         btrfs_end_transaction(trans);
     else if (trans)
         ret = btrfs_end_transaction(trans);
 
     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;
     unsigned int nofs_flag;
     int ret = 0;
 
     /* Check the level of src and dst first */
     if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst))
         return -EINVAL;
 
     /* We hold a transaction handle open, must do a NOFS allocation. */
     nofs_flag = memalloc_nofs_save();
     tmp = ulist_alloc(GFP_KERNEL);
     memalloc_nofs_restore(nofs_flag);
     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(member, parent);
     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;
     unsigned int nofs_flag;
     int ret = 0;
     int ret2;
 
     /* We hold a transaction handle open, must do a NOFS allocation. */
     nofs_flag = memalloc_nofs_save();
     tmp = ulist_alloc(GFP_KERNEL);
     memalloc_nofs_restore(nofs_flag);
     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);
 
     /*
      * Remove the qgroup from sysfs now without holding the qgroup_lock
      * spinlock, since the sysfs_remove_group() function needs to take
      * the mutex kernfs_mutex through kernfs_remove_by_name_ns().
      */
     btrfs_sysfs_del_one_qgroup(fs_info, qgroup);
     kfree(qgroup);
 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_trans_handle *trans,
                    struct btrfs_qgroup_extent_record *qrecord)
 {
     struct ulist *old_root;
     u64 bytenr = qrecord->bytenr;
     int ret;
 
     /*
      * We are always called in a context where we are already holding a
      * transaction handle. Often we are called when adding a data delayed
      * reference from btrfs_truncate_inode_items() (truncating or unlinking),
      * in which case we will be holding a write lock on extent buffer from a
      * subvolume tree. In this case we can't allow btrfs_find_all_roots() to
      * acquire fs_info->commit_root_sem, because that is a higher level lock
      * that must be acquired before locking any extent buffers.
      *
      * So we want btrfs_find_all_roots() to not acquire the commit_root_sem
      * but we can't pass it a non-NULL transaction handle, because otherwise
      * it would not use commit roots and would lock extent buffers, causing
      * a deadlock if it ends up trying to read lock the same extent buffer
      * that was previously write locked at btrfs_truncate_inode_items().
      *
      * So pass a NULL transaction handle to btrfs_find_all_roots() and
      * explicitly tell it to not acquire the commit_root_sem - if we are
      * holding a transaction handle we don't need its protection.
      */
     ASSERT(trans != NULL);
 
     ret = btrfs_find_all_roots(NULL, trans->fs_info, bytenr, 0, &old_root,
                    true);
     if (ret < 0) {
         trans->fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
         btrfs_warn(trans->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(trans, 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 extent_buffer *eb;
             int parent_slot;
 
             eb = src_path->nodes[cur_level + 1];
             parent_slot = src_path->slots[cur_level + 1];
 
             eb = btrfs_read_node_slot(eb, parent_slot);
             if (IS_ERR(eb)) {
                 ret = PTR_ERR(eb);
                 goto out;
             }
 
             src_path->nodes[cur_level] = eb;
 
             btrfs_tree_read_lock(eb);
             src_path->locks[cur_level] = BTRFS_READ_LOCK;
         }
 
         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) {
         int parent_slot;
         u64 child_gen;
 
         /*
          * 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_gen = btrfs_node_ptr_generation(eb, parent_slot);
 
         /* This node is old, no need to trace */
         if (child_gen < last_snapshot)
             goto out;
 
         eb = btrfs_read_node_slot(eb, parent_slot);
         if (IS_ERR(eb)) {
             ret = PTR_ERR(eb);
             goto out;
         }
 
         dst_path->nodes[cur_level] = eb;
         dst_path->slots[cur_level] = 0;
 
         btrfs_tree_read_lock(eb);
         dst_path->locks[cur_level] = BTRFS_READ_LOCK;
         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_extent_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) {
             int parent_slot;
             u64 child_bytenr;
 
             /*
              * We need to get child blockptr 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);
 
             eb = btrfs_read_node_slot(eb, parent_slot);
             if (IS_ERR(eb)) {
                 ret = PTR_ERR(eb);
                 goto out;
             }
 
             path->nodes[level] = eb;
             path->slots[level] = 0;
 
             btrfs_tree_read_lock(eb);
             path->locks[level] = BTRFS_READ_LOCK;
 
             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 parts.
  * 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 resources 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 BTRFS_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, BTRFS_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;
 
     /*
      * There are only two callers of this function.
      *
      * One in create_subvol() in the ioctl context, which needs to hold
      * the qgroup_ioctl_lock.
      *
      * The other one in create_pending_snapshot() where no other qgroup
      * code can modify the fs as they all need to either start a new trans
      * or hold a trans handler, thus we don't need to hold
      * qgroup_ioctl_lock.
      * This would avoid long and complex lock chain and make lockdep happy.
      */
     spin_lock(&fs_info->trans_lock);
     if (trans->transaction->state == TRANS_STATE_COMMIT_DOING)
         committing = true;
     spin_unlock(&fs_info->trans_lock);
 
     if (!committing)
         mutex_lock(&fs_info->qgroup_ioctl_lock);
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
         goto out;
 
     quota_root = fs_info->quota_root;
     if (!quota_root) {
         ret = -EINVAL;
         goto out;
     }
 
     if (inherit) {
         i_qgroups = (u64 *)(inherit + 1);
         nums = inherit->num_qgroups + 2 * inherit->num_ref_copies +
                2 * inherit->num_excl_copies;
         for (i = 0; i < nums; ++i) {
             srcgroup = find_qgroup_rb(fs_info, *i_qgroups);
 
             /*
              * Zero out invalid groups so we can ignore
              * them later.
              */
             if (!srcgroup ||
                 ((srcgroup->qgroupid >> 48) <= (objectid >> 48)))
                 *i_qgroups = 0ULL;
 
             ++i_qgroups;
         }
     }
 
     /*
      * create a tracking group for the subvol itself
      */
     ret = add_qgroup_item(trans, quota_root, objectid);
     if (ret)
         goto out;
 
     /*
      * add qgroup to all inherited groups
      */
     if (inherit) {
         i_qgroups = (u64 *)(inherit + 1);
         for (i = 0; i < inherit->num_qgroups; ++i, ++i_qgroups) {
             if (*i_qgroups == 0)
                 continue;
             ret = add_qgroup_relation_item(trans, objectid,
                                *i_qgroups);
             if (ret && ret != -EEXIST)
                 goto out;
             ret = add_qgroup_relation_item(trans, *i_qgroups,
                                objectid);
             if (ret && ret != -EEXIST)
                 goto out;
         }
         ret = 0;
     }
 
 
     spin_lock(&fs_info->qgroup_lock);
 
     dstgroup = add_qgroup_rb(fs_info, objectid);
     if (IS_ERR(dstgroup)) {
         ret = PTR_ERR(dstgroup);
         goto unlock;
     }
 
     if (inherit && inherit->flags & BTRFS_QGROUP_INHERIT_SET_LIMITS) {
         dstgroup->lim_flags = inherit->lim.flags;
         dstgroup->max_rfer = inherit->lim.max_rfer;
         dstgroup->max_excl = inherit->lim.max_excl;
         dstgroup->rsv_rfer = inherit->lim.rsv_rfer;
         dstgroup->rsv_excl = inherit->lim.rsv_excl;
 
         ret = update_qgroup_limit_item(trans, dstgroup);
         if (ret) {
             fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
             btrfs_info(fs_info,
                    "unable to update quota limit for %llu",
                    dstgroup->qgroupid);
             goto unlock;
         }
     }
 
     if (srcid) {
         srcgroup = find_qgroup_rb(fs_info, srcid);
         if (!srcgroup)
             goto unlock;
 
         /*
          * We call inherit after we clone the root in order to make sure
          * our counts don't go crazy, so at this point the only
          * difference between the two roots should be the root node.
          */
         level_size = fs_info->nodesize;
         dstgroup->rfer = srcgroup->rfer;
         dstgroup->rfer_cmpr = srcgroup->rfer_cmpr;
         dstgroup->excl = level_size;
         dstgroup->excl_cmpr = level_size;
         srcgroup->excl = level_size;
         srcgroup->excl_cmpr = level_size;
 
         /* inherit the limit info */
         dstgroup->lim_flags = srcgroup->lim_flags;
         dstgroup->max_rfer = srcgroup->max_rfer;
         dstgroup->max_excl = srcgroup->max_excl;
         dstgroup->rsv_rfer = srcgroup->rsv_rfer;
         dstgroup->rsv_excl = srcgroup->rsv_excl;
 
         qgroup_dirty(fs_info, dstgroup);
         qgroup_dirty(fs_info, srcgroup);
     }
 
     if (!inherit)
         goto unlock;
 
     i_qgroups = (u64 *)(inherit + 1);
     for (i = 0; i < inherit->num_qgroups; ++i) {
         if (*i_qgroups) {
             ret = add_relation_rb(fs_info, objectid, *i_qgroups);
             if (ret)
                 goto unlock;
         }
         ++i_qgroups;
 
         /*
          * If we're doing a snapshot, and adding the snapshot to a new
          * qgroup, the numbers are guaranteed to be incorrect.
          */
         if (srcid)
             need_rescan = true;
     }
 
     for (i = 0; i <  inherit->num_ref_copies; ++i, i_qgroups += 2) {
         struct btrfs_qgroup *src;
         struct btrfs_qgroup *dst;
 
         if (!i_qgroups[0] || !i_qgroups[1])
             continue;
 
         src = find_qgroup_rb(fs_info, i_qgroups[0]);
         dst = find_qgroup_rb(fs_info, i_qgroups[1]);
 
         if (!src || !dst) {
             ret = -EINVAL;
             goto unlock;
         }
 
         dst->rfer = src->rfer - level_size;
         dst->rfer_cmpr = src->rfer_cmpr - level_size;
 
         /* Manually tweaking numbers certainly needs a rescan */
         need_rescan = true;
     }
     for (i = 0; i <  inherit->num_excl_copies; ++i, i_qgroups += 2) {
         struct btrfs_qgroup *src;
         struct btrfs_qgroup *dst;
 
         if (!i_qgroups[0] || !i_qgroups[1])
             continue;
 
         src = find_qgroup_rb(fs_info, i_qgroups[0]);
         dst = find_qgroup_rb(fs_info, i_qgroups[1]);
 
         if (!src || !dst) {
             ret = -EINVAL;
             goto unlock;
         }
 
         dst->excl = src->excl + level_size;
         dst->excl_cmpr = src->excl_cmpr + level_size;
         need_rescan = true;
     }
 
 unlock:
     spin_unlock(&fs_info->qgroup_lock);
     if (!ret)
         ret = btrfs_sysfs_add_one_qgroup(fs_info, dstgroup);
 out:
     if (!committing)
         mutex_unlock(&fs_info->qgroup_ioctl_lock);
     if (need_rescan)
         fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
     return ret;
 }
 
 static bool qgroup_check_limits(const struct btrfs_qgroup *qg, u64 num_bytes)
 {
     if ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_RFER) &&
         qgroup_rsv_total(qg) + (s64)qg->rfer + num_bytes > qg->max_rfer)
         return false;
 
     if ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_EXCL) &&
         qgroup_rsv_total(qg) + (s64)qg->excl + num_bytes > qg->max_excl)
         return false;
 
     return true;
 }
 
 static int qgroup_reserve(struct btrfs_root *root, u64 num_bytes, bool enforce,
               enum btrfs_qgroup_rsv_type type)
 {
     struct btrfs_qgroup *qgroup;
     struct btrfs_fs_info *fs_info = root->fs_info;
     u64 ref_root = root->root_key.objectid;
     int ret = 0;
     struct ulist_node *unode;
     struct ulist_iterator uiter;
 
     if (!is_fstree(ref_root))
         return 0;
 
     if (num_bytes == 0)
         return 0;
 
     if (test_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags) &&
         capable(CAP_SYS_RESOURCE))
         enforce = false;
 
     spin_lock(&fs_info->qgroup_lock);
     if (!fs_info->quota_root)
         goto out;
 
     qgroup = find_qgroup_rb(fs_info, ref_root);
     if (!qgroup)
         goto out;
 
     /*
      * in a first step, we check all affected qgroups if any limits would
      * be exceeded
      */
     ulist_reinit(fs_info->qgroup_ulist);
     ret = ulist_add(fs_info->qgroup_ulist, qgroup->qgroupid,
             qgroup_to_aux(qgroup), GFP_ATOMIC);
     if (ret < 0)
         goto out;
     ULIST_ITER_INIT(&uiter);
     while ((unode = ulist_next(fs_info->qgroup_ulist, &uiter))) {
         struct btrfs_qgroup *qg;
         struct btrfs_qgroup_list *glist;
 
         qg = unode_aux_to_qgroup(unode);
 
         if (enforce && !qgroup_check_limits(qg, num_bytes)) {
             ret = -EDQUOT;
             goto out;
         }
 
         list_for_each_entry(glist, &qg->groups, next_group) {
             ret = ulist_add(fs_info->qgroup_ulist,
                     glist->group->qgroupid,
                     qgroup_to_aux(glist->group), GFP_ATOMIC);
             if (ret < 0)
                 goto out;
         }
     }
     ret = 0;
     /*
      * no limits exceeded, now record the reservation into all qgroups
      */
     ULIST_ITER_INIT(&uiter);
     while ((unode = ulist_next(fs_info->qgroup_ulist, &uiter))) {
         struct btrfs_qgroup *qg;
 
         qg = unode_aux_to_qgroup(unode);
 
         qgroup_rsv_add(fs_info, qg, num_bytes, type);
     }
 
 out:
     spin_unlock(&fs_info->qgroup_lock);
     return ret;
 }
 
 /*
  * Free @num_bytes of reserved space with @type for qgroup.  (Normally level 0
  * qgroup).
  *
  * Will handle all higher level qgroup too.
  *
  * NOTE: If @num_bytes is (u64)-1, this means to free all bytes of this qgroup.
  * This special case is only used for META_PERTRANS type.
  */
 void btrfs_qgroup_free_refroot(struct btrfs_fs_info *fs_info,
                    u64 ref_root, u64 num_bytes,
                    enum btrfs_qgroup_rsv_type type)
 {
     struct btrfs_qgroup *qgroup;
     struct ulist_node *unode;
     struct ulist_iterator uiter;
     int ret = 0;
 
     if (!is_fstree(ref_root))
         return;
 
     if (num_bytes == 0)
         return;
 
     if (num_bytes == (u64)-1 && type != BTRFS_QGROUP_RSV_META_PERTRANS) {
         WARN(1, "%s: Invalid type to free", __func__);
         return;
     }
     spin_lock(&fs_info->qgroup_lock);
 
     if (!fs_info->quota_root)
         goto out;
 
     qgroup = find_qgroup_rb(fs_info, ref_root);
     if (!qgroup)
         goto out;
 
     if (num_bytes == (u64)-1)
         /*
          * We're freeing all pertrans rsv, get reserved value from
          * level 0 qgroup as real num_bytes to free.
          */
         num_bytes = qgroup->rsv.values[type];
 
     ulist_reinit(fs_info->qgroup_ulist);
     ret = ulist_add(fs_info->qgroup_ulist, qgroup->qgroupid,
             qgroup_to_aux(qgroup), GFP_ATOMIC);
     if (ret < 0)
         goto out;
     ULIST_ITER_INIT(&uiter);
     while ((unode = ulist_next(fs_info->qgroup_ulist, &uiter))) {
         struct btrfs_qgroup *qg;
         struct btrfs_qgroup_list *glist;
 
         qg = unode_aux_to_qgroup(unode);
 
         qgroup_rsv_release(fs_info, qg, num_bytes, type);
 
         list_for_each_entry(glist, &qg->groups, next_group) {
             ret = ulist_add(fs_info->qgroup_ulist,
                     glist->group->qgroupid,
                     qgroup_to_aux(glist->group), GFP_ATOMIC);
             if (ret < 0)
                 goto out;
         }
     }
 
 out:
     spin_unlock(&fs_info->qgroup_lock);
 }
 
 /*
  * Check if the leaf is the last leaf. Which means all node pointers
  * are at their last position.
  */
 static bool is_last_leaf(struct btrfs_path *path)
 {
     int i;
 
     for (i = 1; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
         if (path->slots[i] != btrfs_header_nritems(path->nodes[i]) - 1)
             return false;
     }
     return true;
 }
 
 /*
  * returns < 0 on error, 0 when more leafs are to be scanned.
  * returns 1 when done.
  */
 static int qgroup_rescan_leaf(struct btrfs_trans_handle *trans,
                   struct btrfs_path *path)
 {
     struct btrfs_fs_info *fs_info = trans->fs_info;
     struct btrfs_root *extent_root;
     struct btrfs_key found;
     struct extent_buffer *scratch_leaf = NULL;
     struct ulist *roots = NULL;
     u64 num_bytes;
     bool done;
     int slot;
     int ret;
 
     mutex_lock(&fs_info->qgroup_rescan_lock);
     extent_root = btrfs_extent_root(fs_info,
                 fs_info->qgroup_rescan_progress.objectid);
     ret = btrfs_search_slot_for_read(extent_root,
                      &fs_info->qgroup_rescan_progress,
                      path, 1, 0);
 
     btrfs_debug(fs_info,
         "current progress key (%llu %u %llu), search_slot ret %d",
         fs_info->qgroup_rescan_progress.objectid,
         fs_info->qgroup_rescan_progress.type,
         fs_info->qgroup_rescan_progress.offset, ret);
 
     if (ret) {
         /*
          * The rescan is about to end, we will not be scanning any
          * further blocks. We cannot unset the RESCAN flag here, because
          * we want to commit the transaction if everything went well.
          * To make the live accounting work in this phase, we set our
          * scan progress pointer such that every real extent objectid
          * will be smaller.
          */
         fs_info->qgroup_rescan_progress.objectid = (u64)-1;
         btrfs_release_path(path);
         mutex_unlock(&fs_info->qgroup_rescan_lock);
         return ret;
     }
     done = is_last_leaf(path);
 
     btrfs_item_key_to_cpu(path->nodes[0], &found,
                   btrfs_header_nritems(path->nodes[0]) - 1);
     fs_info->qgroup_rescan_progress.objectid = found.objectid + 1;
 
     scratch_leaf = btrfs_clone_extent_buffer(path->nodes[0]);
     if (!scratch_leaf) {
         ret = -ENOMEM;
         mutex_unlock(&fs_info->qgroup_rescan_lock);
         goto out;
     }
     slot = path->slots[0];
     btrfs_release_path(path);
     mutex_unlock(&fs_info->qgroup_rescan_lock);
 
     for (; slot < btrfs_header_nritems(scratch_leaf); ++slot) {
         btrfs_item_key_to_cpu(scratch_leaf, &found, slot);
         if (found.type != BTRFS_EXTENT_ITEM_KEY &&
             found.type != BTRFS_METADATA_ITEM_KEY)
             continue;
         if (found.type == BTRFS_METADATA_ITEM_KEY)
             num_bytes = fs_info->nodesize;
         else
             num_bytes = found.offset;
 
         ret = btrfs_find_all_roots(NULL, fs_info, found.objectid, 0,
                        &roots, false);
         if (ret < 0)
             goto out;
         /* For rescan, just pass old_roots as NULL */
         ret = btrfs_qgroup_account_extent(trans, found.objectid,
                           num_bytes, NULL, roots);
         if (ret < 0)
             goto out;
     }
 out:
     if (scratch_leaf)
         free_extent_buffer(scratch_leaf);
 
     if (done && !ret) {
         ret = 1;
         fs_info->qgroup_rescan_progress.objectid = (u64)-1;
     }
     return ret;
 }
 
 static bool rescan_should_stop(struct btrfs_fs_info *fs_info)
 {
     return btrfs_fs_closing(fs_info) ||
         test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state) ||
         !test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
 }
 
 static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
 {
     struct btrfs_fs_info *fs_info = container_of(work, struct btrfs_fs_info,
                              qgroup_rescan_work);
     struct btrfs_path *path;
     struct btrfs_trans_handle *trans = NULL;
     int err = -ENOMEM;
     int ret = 0;
     bool stopped = false;
 
     path = btrfs_alloc_path();
     if (!path)
         goto out;
     /*
      * Rescan should only search for commit root, and any later difference
      * should be recorded by qgroup
      */
     path->search_commit_root = 1;
     path->skip_locking = 1;
 
     err = 0;
     while (!err && !(stopped = rescan_should_stop(fs_info))) {
         trans = btrfs_start_transaction(fs_info->fs_root, 0);
         if (IS_ERR(trans)) {
             err = PTR_ERR(trans);
             break;
         }
 
         err = qgroup_rescan_leaf(trans, path);
 
         if (err > 0)
             btrfs_commit_transaction(trans);
         else
             btrfs_end_transaction(trans);
     }
 
 out:
     btrfs_free_path(path);
 
     mutex_lock(&fs_info->qgroup_rescan_lock);
     if (err > 0 &&
         fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT) {
         fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
     } else if (err < 0 || stopped) {
         fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
     }
     mutex_unlock(&fs_info->qgroup_rescan_lock);
 
     /*
      * only update status, since the previous part has already updated the
      * qgroup info.
      */
     trans = btrfs_start_transaction(fs_info->quota_root, 1);
     if (IS_ERR(trans)) {
         err = PTR_ERR(trans);
         trans = NULL;
         btrfs_err(fs_info,
               "fail to start transaction for status update: %d",
               err);
     }
 
     mutex_lock(&fs_info->qgroup_rescan_lock);
     if (!stopped)
         fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
     if (trans) {
         ret = update_qgroup_status_item(trans);
         if (ret < 0) {
             err = ret;
             btrfs_err(fs_info, "fail to update qgroup status: %d",
                   err);
         }
     }
     fs_info->qgroup_rescan_running = false;
     complete_all(&fs_info->qgroup_rescan_completion);
     mutex_unlock(&fs_info->qgroup_rescan_lock);
 
     if (!trans)
         return;
 
     btrfs_end_transaction(trans);
 
     if (stopped) {
         btrfs_info(fs_info, "qgroup scan paused");
     } else if (err >= 0) {
         btrfs_info(fs_info, "qgroup scan completed%s",
             err > 0 ? " (inconsistency flag cleared)" : "");
     } else {
         btrfs_err(fs_info, "qgroup scan failed with %d", err);
     }
 }
 
 /*
  * Checks that (a) no rescan is running and (b) quota is enabled. Allocates all
  * memory required for the rescan context.
  */
 static int
 qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,
            int init_flags)
 {
     int ret = 0;
 
     if (!init_flags) {
         /* we're resuming qgroup rescan at mount time */
         if (!(fs_info->qgroup_flags &
               BTRFS_QGROUP_STATUS_FLAG_RESCAN)) {
             btrfs_warn(fs_info,
             "qgroup rescan init failed, qgroup rescan is not queued");
             ret = -EINVAL;
         } else if (!(fs_info->qgroup_flags &
                  BTRFS_QGROUP_STATUS_FLAG_ON)) {
             btrfs_warn(fs_info,
             "qgroup rescan init failed, qgroup is not enabled");
             ret = -EINVAL;
         }
 
         if (ret)
             return ret;
     }
 
     mutex_lock(&fs_info->qgroup_rescan_lock);
 
     if (init_flags) {
         if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
             btrfs_warn(fs_info,
                    "qgroup rescan is already in progress");
             ret = -EINPROGRESS;
         } else if (!(fs_info->qgroup_flags &
                  BTRFS_QGROUP_STATUS_FLAG_ON)) {
             btrfs_warn(fs_info,
             "qgroup rescan init failed, qgroup is not enabled");
             ret = -EINVAL;
         } else if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) {
             /* Quota disable is in progress */
             ret = -EBUSY;
         }
 
         if (ret) {
             mutex_unlock(&fs_info->qgroup_rescan_lock);
             return ret;
         }
         fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN;
     }
 
     memset(&fs_info->qgroup_rescan_progress, 0,
         sizeof(fs_info->qgroup_rescan_progress));
     fs_info->qgroup_rescan_progress.objectid = progress_objectid;
     init_completion(&fs_info->qgroup_rescan_completion);
     mutex_unlock(&fs_info->qgroup_rescan_lock);
 
     btrfs_init_work(&fs_info->qgroup_rescan_work,
             btrfs_qgroup_rescan_worker, NULL, NULL);
     return 0;
 }
 
 static void
 qgroup_rescan_zero_tracking(struct btrfs_fs_info *fs_info)
 {
     struct rb_node *n;
     struct btrfs_qgroup *qgroup;
 
     spin_lock(&fs_info->qgroup_lock);
     /* clear all current qgroup tracking information */
     for (n = rb_first(&fs_info->qgroup_tree); n; n = rb_next(n)) {
         qgroup = rb_entry(n, struct btrfs_qgroup, node);
         qgroup->rfer = 0;
         qgroup->rfer_cmpr = 0;
         qgroup->excl = 0;
         qgroup->excl_cmpr = 0;
         qgroup_dirty(fs_info, qgroup);
     }
     spin_unlock(&fs_info->qgroup_lock);
 }
 
 int
 btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
 {
     int ret = 0;
     struct btrfs_trans_handle *trans;
 
     ret = qgroup_rescan_init(fs_info, 0, 1);
     if (ret)
         return ret;
 
     /*
      * We have set the rescan_progress to 0, which means no more
      * delayed refs will be accounted by btrfs_qgroup_account_ref.
      * However, btrfs_qgroup_account_ref may be right after its call
      * to btrfs_find_all_roots, in which case it would still do the
      * accounting.
      * To solve this, we're committing the transaction, which will
      * ensure we run all delayed refs and only after that, we are
      * going to clear all tracking information for a clean start.
      */
 
     trans = btrfs_join_transaction(fs_info->fs_root);
     if (IS_ERR(trans)) {
         fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
         return PTR_ERR(trans);
     }
     ret = btrfs_commit_transaction(trans);
     if (ret) {
         fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
         return ret;
     }
 
     qgroup_rescan_zero_tracking(fs_info);
 
     mutex_lock(&fs_info->qgroup_rescan_lock);
     fs_info->qgroup_rescan_running = true;
     btrfs_queue_work(fs_info->qgroup_rescan_workers,
              &fs_info->qgroup_rescan_work);
     mutex_unlock(&fs_info->qgroup_rescan_lock);
 
     return 0;
 }
 
 int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,
                      bool interruptible)
 {
     int running;
     int ret = 0;
 
     mutex_lock(&fs_info->qgroup_rescan_lock);
     running = fs_info->qgroup_rescan_running;
     mutex_unlock(&fs_info->qgroup_rescan_lock);
 
     if (!running)
         return 0;
 
     if (interruptible)
         ret = wait_for_completion_interruptible(
                     &fs_info->qgroup_rescan_completion);
     else
         wait_for_completion(&fs_info->qgroup_rescan_completion);
 
     return ret;
 }
 
 /*
  * this is only called from open_ctree where we're still single threaded, thus
  * locking is omitted here.
  */
 void
 btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info)
 {
     if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
         mutex_lock(&fs_info->qgroup_rescan_lock);
         fs_info->qgroup_rescan_running = true;
         btrfs_queue_work(fs_info->qgroup_rescan_workers,
                  &fs_info->qgroup_rescan_work);
         mutex_unlock(&fs_info->qgroup_rescan_lock);
     }
 }
 
 #define rbtree_iterate_from_safe(node, next, start)             \
        for (node = start; node && ({ next = rb_next(node); 1;}); node = next)
 
 static int qgroup_unreserve_range(struct btrfs_inode *inode,
                   struct extent_changeset *reserved, u64 start,
                   u64 len)
 {
     struct rb_node *node;
     struct rb_node *next;
     struct ulist_node *entry;
     int ret = 0;
 
     node = reserved->range_changed.root.rb_node;
     if (!node)
         return 0;
     while (node) {
         entry = rb_entry(node, struct ulist_node, rb_node);
         if (entry->val < start)
             node = node->rb_right;
         else
             node = node->rb_left;
     }
 
     if (entry->val > start && rb_prev(&entry->rb_node))
         entry = rb_entry(rb_prev(&entry->rb_node), struct ulist_node,
                  rb_node);
 
     rbtree_iterate_from_safe(node, next, &entry->rb_node) {
         u64 entry_start;
         u64 entry_end;
         u64 entry_len;
         int clear_ret;
 
         entry = rb_entry(node, struct ulist_node, rb_node);
         entry_start = entry->val;
         entry_end = entry->aux;
         entry_len = entry_end - entry_start + 1;
 
         if (entry_start >= start + len)
             break;
         if (entry_start + entry_len <= start)
             continue;
         /*
          * Now the entry is in [start, start + len), revert the
          * EXTENT_QGROUP_RESERVED bit.
          */
         clear_ret = clear_extent_bits(&inode->io_tree, entry_start,
                           entry_end, EXTENT_QGROUP_RESERVED);
         if (!ret && clear_ret < 0)
             ret = clear_ret;
 
         ulist_del(&reserved->range_changed, entry->val, entry->aux);
         if (likely(reserved->bytes_changed >= entry_len)) {
             reserved->bytes_changed -= entry_len;
         } else {
             WARN_ON(1);
             reserved->bytes_changed = 0;
         }
     }
 
     return ret;
 }
 
 /*
  * Try to free some space for qgroup.
  *
  * For qgroup, there are only 3 ways to free qgroup space:
  * - Flush nodatacow write
  *   Any nodatacow write will free its reserved data space at run_delalloc_range().
  *   In theory, we should only flush nodatacow inodes, but it's not yet
  *   possible, so we need to flush the whole root.
  *
  * - Wait for ordered extents
  *   When ordered extents are finished, their reserved metadata is finally
  *   converted to per_trans status, which can be freed by later commit
  *   transaction.
  *
  * - Commit transaction
  *   This would free the meta_per_trans space.
  *   In theory this shouldn't provide much space, but any more qgroup space
  *   is needed.
  */
 static int try_flush_qgroup(struct btrfs_root *root)
 {
     struct btrfs_trans_handle *trans;
     int ret;
 
     /* Can't hold an open transaction or we run the risk of deadlocking. */
     ASSERT(current->journal_info == NULL);
     if (WARN_ON(current->journal_info))
         return 0;
 
     /*
      * We don't want to run flush again and again, so if there is a running
      * one, we won't try to start a new flush, but exit directly.
      */
     if (test_and_set_bit(BTRFS_ROOT_QGROUP_FLUSHING, &root->state)) {
         wait_event(root->qgroup_flush_wait,
             !test_bit(BTRFS_ROOT_QGROUP_FLUSHING, &root->state));
         return 0;
     }
 
     ret = btrfs_start_delalloc_snapshot(root, true);
     if (ret < 0)
         goto out;
     btrfs_wait_ordered_extents(root, U64_MAX, 0, (u64)-1);
 
     trans = btrfs_join_transaction(root);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out;
     }
 
     ret = btrfs_commit_transaction(trans);
 out:
     clear_bit(BTRFS_ROOT_QGROUP_FLUSHING, &root->state);
     wake_up(&root->qgroup_flush_wait);
     return ret;
 }
 
 static int qgroup_reserve_data(struct btrfs_inode *inode,
             struct extent_changeset **reserved_ret, u64 start,
             u64 len)
 {
     struct btrfs_root *root = inode->root;
     struct extent_changeset *reserved;
     bool new_reserved = false;
     u64 orig_reserved;
     u64 to_reserve;
     int ret;
 
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &root->fs_info->flags) ||
         !is_fstree(root->root_key.objectid) || len == 0)
         return 0;
 
     /* @reserved parameter is mandatory for qgroup */
     if (WARN_ON(!reserved_ret))
         return -EINVAL;
     if (!*reserved_ret) {
         new_reserved = true;
         *reserved_ret = extent_changeset_alloc();
         if (!*reserved_ret)
             return -ENOMEM;
     }
     reserved = *reserved_ret;
     /* Record already reserved space */
     orig_reserved = reserved->bytes_changed;
     ret = set_record_extent_bits(&inode->io_tree, start,
             start + len -1, EXTENT_QGROUP_RESERVED, reserved);
 
     /* Newly reserved space */
     to_reserve = reserved->bytes_changed - orig_reserved;
     trace_btrfs_qgroup_reserve_data(&inode->vfs_inode, start, len,
                     to_reserve, QGROUP_RESERVE);
     if (ret < 0)
         goto out;
     ret = qgroup_reserve(root, to_reserve, true, BTRFS_QGROUP_RSV_DATA);
     if (ret < 0)
         goto cleanup;
 
     return ret;
 
 cleanup:
     qgroup_unreserve_range(inode, reserved, start, len);
 out:
     if (new_reserved) {
         extent_changeset_free(reserved);
         *reserved_ret = NULL;
     }
     return ret;
 }
 
 /*
  * Reserve qgroup space for range [start, start + len).
  *
  * This function will either reserve space from related qgroups or do nothing
  * if the range is already reserved.
  *
  * Return 0 for successful reservation
  * Return <0 for error (including -EQUOT)
  *
  * NOTE: This function may sleep for memory allocation, dirty page flushing and
  *   commit transaction. So caller should not hold any dirty page locked.
  */
 int btrfs_qgroup_reserve_data(struct btrfs_inode *inode,
             struct extent_changeset **reserved_ret, u64 start,
             u64 len)
 {
     int ret;
 
     ret = qgroup_reserve_data(inode, reserved_ret, start, len);
     if (ret <= 0 && ret != -EDQUOT)
         return ret;
 
     ret = try_flush_qgroup(inode->root);
     if (ret < 0)
         return ret;
     return qgroup_reserve_data(inode, reserved_ret, start, len);
 }
 
 /* Free ranges specified by @reserved, normally in error path */
 static int qgroup_free_reserved_data(struct btrfs_inode *inode,
             struct extent_changeset *reserved, u64 start, u64 len)
 {
     struct btrfs_root *root = inode->root;
     struct ulist_node *unode;
     struct ulist_iterator uiter;
     struct extent_changeset changeset;
     int freed = 0;
     int ret;
 
     extent_changeset_init(&changeset);
     len = round_up(start + len, root->fs_info->sectorsize);
     start = round_down(start, root->fs_info->sectorsize);
 
     ULIST_ITER_INIT(&uiter);
     while ((unode = ulist_next(&reserved->range_changed, &uiter))) {
         u64 range_start = unode->val;
         /* unode->aux is the inclusive end */
         u64 range_len = unode->aux - range_start + 1;
         u64 free_start;
         u64 free_len;
 
         extent_changeset_release(&changeset);
 
         /* Only free range in range [start, start + len) */
         if (range_start >= start + len ||
             range_start + range_len <= start)
             continue;
         free_start = max(range_start, start);
         free_len = min(start + len, range_start + range_len) -
                free_start;
         /*
          * TODO: To also modify reserved->ranges_reserved to reflect
          * the modification.
          *
          * However as long as we free qgroup reserved according to
          * EXTENT_QGROUP_RESERVED, we won't double free.
          * So not need to rush.
          */
         ret = clear_record_extent_bits(&inode->io_tree, free_start,
                 free_start + free_len - 1,
                 EXTENT_QGROUP_RESERVED, &changeset);
         if (ret < 0)
             goto out;
         freed += changeset.bytes_changed;
     }
     btrfs_qgroup_free_refroot(root->fs_info, root->root_key.objectid, freed,
                   BTRFS_QGROUP_RSV_DATA);
     ret = freed;
 out:
     extent_changeset_release(&changeset);
     return ret;
 }
 
 static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
             struct extent_changeset *reserved, u64 start, u64 len,
             int free)
 {
     struct extent_changeset changeset;
     int trace_op = QGROUP_RELEASE;
     int ret;
 
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &inode->root->fs_info->flags))
         return 0;
 
     /* In release case, we shouldn't have @reserved */
     WARN_ON(!free && reserved);
     if (free && reserved)
         return qgroup_free_reserved_data(inode, reserved, start, len);
     extent_changeset_init(&changeset);
     ret = clear_record_extent_bits(&inode->io_tree, start, start + len -1,
                        EXTENT_QGROUP_RESERVED, &changeset);
     if (ret < 0)
         goto out;
 
     if (free)
         trace_op = QGROUP_FREE;
     trace_btrfs_qgroup_release_data(&inode->vfs_inode, start, len,
                     changeset.bytes_changed, trace_op);
     if (free)
         btrfs_qgroup_free_refroot(inode->root->fs_info,
                 inode->root->root_key.objectid,
                 changeset.bytes_changed, BTRFS_QGROUP_RSV_DATA);
     ret = changeset.bytes_changed;
 out:
     extent_changeset_release(&changeset);
     return ret;
 }
 
 /*
  * Free a reserved space range from io_tree and related qgroups
  *
  * Should be called when a range of pages get invalidated before reaching disk.
  * Or for error cleanup case.
  * if @reserved is given, only reserved range in [@start, @start + @len) will
  * be freed.
  *
  * For data written to disk, use btrfs_qgroup_release_data().
  *
  * NOTE: This function may sleep for memory allocation.
  */
 int btrfs_qgroup_free_data(struct btrfs_inode *inode,
             struct extent_changeset *reserved, u64 start, u64 len)
 {
     return __btrfs_qgroup_release_data(inode, reserved, start, len, 1);
 }
 
 /*
  * Release a reserved space range from io_tree only.
  *
  * Should be called when a range of pages get written to disk and corresponding
  * FILE_EXTENT is inserted into corresponding root.
  *
  * Since new qgroup accounting framework will only update qgroup numbers at
  * commit_transaction() time, its reserved space shouldn't be freed from
  * related qgroups.
  *
  * But we should release the range from io_tree, to allow further write to be
  * COWed.
  *
  * NOTE: This function may sleep for memory allocation.
  */
 int btrfs_qgroup_release_data(struct btrfs_inode *inode, u64 start, u64 len)
 {
     return __btrfs_qgroup_release_data(inode, NULL, start, len, 0);
 }
 
 static void add_root_meta_rsv(struct btrfs_root *root, int num_bytes,
                   enum btrfs_qgroup_rsv_type type)
 {
     if (type != BTRFS_QGROUP_RSV_META_PREALLOC &&
         type != BTRFS_QGROUP_RSV_META_PERTRANS)
         return;
     if (num_bytes == 0)
         return;
 
     spin_lock(&root->qgroup_meta_rsv_lock);
     if (type == BTRFS_QGROUP_RSV_META_PREALLOC)
         root->qgroup_meta_rsv_prealloc += num_bytes;
     else
         root->qgroup_meta_rsv_pertrans += num_bytes;
     spin_unlock(&root->qgroup_meta_rsv_lock);
 }
 
 static int sub_root_meta_rsv(struct btrfs_root *root, int num_bytes,
                  enum btrfs_qgroup_rsv_type type)
 {
     if (type != BTRFS_QGROUP_RSV_META_PREALLOC &&
         type != BTRFS_QGROUP_RSV_META_PERTRANS)
         return 0;
     if (num_bytes == 0)
         return 0;
 
     spin_lock(&root->qgroup_meta_rsv_lock);
     if (type == BTRFS_QGROUP_RSV_META_PREALLOC) {
         num_bytes = min_t(u64, root->qgroup_meta_rsv_prealloc,
                   num_bytes);
         root->qgroup_meta_rsv_prealloc -= num_bytes;
     } else {
         num_bytes = min_t(u64, root->qgroup_meta_rsv_pertrans,
                   num_bytes);
         root->qgroup_meta_rsv_pertrans -= num_bytes;
     }
     spin_unlock(&root->qgroup_meta_rsv_lock);
     return num_bytes;
 }
 
 int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
                   enum btrfs_qgroup_rsv_type type, bool enforce)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
     int ret;
 
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) ||
         !is_fstree(root->root_key.objectid) || num_bytes == 0)
         return 0;
 
     BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
     trace_qgroup_meta_reserve(root, (s64)num_bytes, type);
     ret = qgroup_reserve(root, num_bytes, enforce, type);
     if (ret < 0)
         return ret;
     /*
      * Record what we have reserved into root.
      *
      * To avoid quota disabled->enabled underflow.
      * In that case, we may try to free space we haven't reserved
      * (since quota was disabled), so record what we reserved into root.
      * And ensure later release won't underflow this number.
      */
     add_root_meta_rsv(root, num_bytes, type);
     return ret;
 }
 
 int __btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
                 enum btrfs_qgroup_rsv_type type, bool enforce,
                 bool noflush)
 {
     int ret;
 
     ret = btrfs_qgroup_reserve_meta(root, num_bytes, type, enforce);
     if ((ret <= 0 && ret != -EDQUOT) || noflush)
         return ret;
 
     ret = try_flush_qgroup(root);
     if (ret < 0)
         return ret;
     return btrfs_qgroup_reserve_meta(root, num_bytes, type, enforce);
 }
 
 void btrfs_qgroup_free_meta_all_pertrans(struct btrfs_root *root)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
 
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) ||
         !is_fstree(root->root_key.objectid))
         return;
 
     /* TODO: Update trace point to handle such free */
     trace_qgroup_meta_free_all_pertrans(root);
     /* Special value -1 means to free all reserved space */
     btrfs_qgroup_free_refroot(fs_info, root->root_key.objectid, (u64)-1,
                   BTRFS_QGROUP_RSV_META_PERTRANS);
 }
 
 void __btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes,
                   enum btrfs_qgroup_rsv_type type)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
 
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) ||
         !is_fstree(root->root_key.objectid))
         return;
 
     /*
      * reservation for META_PREALLOC can happen before quota is enabled,
      * which can lead to underflow.
      * Here ensure we will only free what we really have reserved.
      */
     num_bytes = sub_root_meta_rsv(root, num_bytes, type);
     BUG_ON(num_bytes != round_down(num_bytes, fs_info->nodesize));
     trace_qgroup_meta_reserve(root, -(s64)num_bytes, type);
     btrfs_qgroup_free_refroot(fs_info, root->root_key.objectid,
                   num_bytes, type);
 }
 
 static void qgroup_convert_meta(struct btrfs_fs_info *fs_info, u64 ref_root,
                 int num_bytes)
 {
     struct btrfs_qgroup *qgroup;
     struct ulist_node *unode;
     struct ulist_iterator uiter;
     int ret = 0;
 
     if (num_bytes == 0)
         return;
     if (!fs_info->quota_root)
         return;
 
     spin_lock(&fs_info->qgroup_lock);
     qgroup = find_qgroup_rb(fs_info, ref_root);
     if (!qgroup)
         goto out;
     ulist_reinit(fs_info->qgroup_ulist);
     ret = ulist_add(fs_info->qgroup_ulist, qgroup->qgroupid,
                qgroup_to_aux(qgroup), GFP_ATOMIC);
     if (ret < 0)
         goto out;
     ULIST_ITER_INIT(&uiter);
     while ((unode = ulist_next(fs_info->qgroup_ulist, &uiter))) {
         struct btrfs_qgroup *qg;
         struct btrfs_qgroup_list *glist;
 
         qg = unode_aux_to_qgroup(unode);
 
         qgroup_rsv_release(fs_info, qg, num_bytes,
                 BTRFS_QGROUP_RSV_META_PREALLOC);
         qgroup_rsv_add(fs_info, qg, num_bytes,
                 BTRFS_QGROUP_RSV_META_PERTRANS);
         list_for_each_entry(glist, &qg->groups, next_group) {
             ret = ulist_add(fs_info->qgroup_ulist,
                     glist->group->qgroupid,
                     qgroup_to_aux(glist->group), GFP_ATOMIC);
             if (ret < 0)
                 goto out;
         }
     }
 out:
     spin_unlock(&fs_info->qgroup_lock);
 }
 
 void btrfs_qgroup_convert_reserved_meta(struct btrfs_root *root, int num_bytes)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
 
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) ||
         !is_fstree(root->root_key.objectid))
         return;
     /* Same as btrfs_qgroup_free_meta_prealloc() */
     num_bytes = sub_root_meta_rsv(root, num_bytes,
                       BTRFS_QGROUP_RSV_META_PREALLOC);
     trace_qgroup_meta_convert(root, num_bytes);
     qgroup_convert_meta(fs_info, root->root_key.objectid, num_bytes);
 }
 
 /*
  * Check qgroup reserved space leaking, normally at destroy inode
  * time
  */
 void btrfs_qgroup_check_reserved_leak(struct btrfs_inode *inode)
 {
     struct extent_changeset changeset;
     struct ulist_node *unode;
     struct ulist_iterator iter;
     int ret;
 
     extent_changeset_init(&changeset);
     ret = clear_record_extent_bits(&inode->io_tree, 0, (u64)-1,
             EXTENT_QGROUP_RESERVED, &changeset);
 
     WARN_ON(ret < 0);
     if (WARN_ON(changeset.bytes_changed)) {
         ULIST_ITER_INIT(&iter);
         while ((unode = ulist_next(&changeset.range_changed, &iter))) {
             btrfs_warn(inode->root->fs_info,
         "leaking qgroup reserved space, ino: %llu, start: %llu, end: %llu",
                 btrfs_ino(inode), unode->val, unode->aux);
         }
         btrfs_qgroup_free_refroot(inode->root->fs_info,
                 inode->root->root_key.objectid,
                 changeset.bytes_changed, BTRFS_QGROUP_RSV_DATA);
 
     }
     extent_changeset_release(&changeset);
 }
 
 void btrfs_qgroup_init_swapped_blocks(
     struct btrfs_qgroup_swapped_blocks *swapped_blocks)
 {
     int i;
 
     spin_lock_init(&swapped_blocks->lock);
     for (i = 0; i < BTRFS_MAX_LEVEL; i++)
         swapped_blocks->blocks[i] = RB_ROOT;
     swapped_blocks->swapped = false;
 }
 
 /*
  * Delete all swapped blocks record of @root.
  * Every record here means we skipped a full subtree scan for qgroup.
  *
  * Gets called when committing one transaction.
  */
 void btrfs_qgroup_clean_swapped_blocks(struct btrfs_root *root)
 {
     struct btrfs_qgroup_swapped_blocks *swapped_blocks;
     int i;
 
     swapped_blocks = &root->swapped_blocks;
 
     spin_lock(&swapped_blocks->lock);
     if (!swapped_blocks->swapped)
         goto out;
     for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
         struct rb_root *cur_root = &swapped_blocks->blocks[i];
         struct btrfs_qgroup_swapped_block *entry;
         struct btrfs_qgroup_swapped_block *next;
 
         rbtree_postorder_for_each_entry_safe(entry, next, cur_root,
                              node)
             kfree(entry);
         swapped_blocks->blocks[i] = RB_ROOT;
     }
     swapped_blocks->swapped = false;
 out:
     spin_unlock(&swapped_blocks->lock);
 }
 
 /*
  * Add subtree roots record into @subvol_root.
  *
  * @subvol_root:    tree root of the subvolume tree get swapped
  * @bg:         block group under balance
  * @subvol_parent/slot: pointer to the subtree root in subvolume tree
  * @reloc_parent/slot:  pointer to the subtree root in reloc tree
  *          BOTH POINTERS ARE BEFORE TREE SWAP
  * @last_snapshot:  last snapshot generation of the subvolume tree
  */
 int btrfs_qgroup_add_swapped_blocks(struct btrfs_trans_handle *trans,
         struct btrfs_root *subvol_root,
         struct btrfs_block_group *bg,
         struct extent_buffer *subvol_parent, int subvol_slot,
         struct extent_buffer *reloc_parent, int reloc_slot,
         u64 last_snapshot)
 {
     struct btrfs_fs_info *fs_info = subvol_root->fs_info;
     struct btrfs_qgroup_swapped_blocks *blocks = &subvol_root->swapped_blocks;
     struct btrfs_qgroup_swapped_block *block;
     struct rb_node **cur;
     struct rb_node *parent = NULL;
     int level = btrfs_header_level(subvol_parent) - 1;
     int ret = 0;
 
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
         return 0;
 
     if (btrfs_node_ptr_generation(subvol_parent, subvol_slot) >
         btrfs_node_ptr_generation(reloc_parent, reloc_slot)) {
         btrfs_err_rl(fs_info,
         "%s: bad parameter order, subvol_gen=%llu reloc_gen=%llu",
             __func__,
             btrfs_node_ptr_generation(subvol_parent, subvol_slot),
             btrfs_node_ptr_generation(reloc_parent, reloc_slot));
         return -EUCLEAN;
     }
 
     block = kmalloc(sizeof(*block), GFP_NOFS);
     if (!block) {
         ret = -ENOMEM;
         goto out;
     }
 
     /*
      * @reloc_parent/slot is still before swap, while @block is going to
      * record the bytenr after swap, so we do the swap here.
      */
     block->subvol_bytenr = btrfs_node_blockptr(reloc_parent, reloc_slot);
     block->subvol_generation = btrfs_node_ptr_generation(reloc_parent,
                                  reloc_slot);
     block->reloc_bytenr = btrfs_node_blockptr(subvol_parent, subvol_slot);
     block->reloc_generation = btrfs_node_ptr_generation(subvol_parent,
                                 subvol_slot);
     block->last_snapshot = last_snapshot;
     block->level = level;
 
     /*
      * If we have bg == NULL, we're called from btrfs_recover_relocation(),
      * no one else can modify tree blocks thus we qgroup will not change
      * no matter the value of trace_leaf.
      */
     if (bg && bg->flags & BTRFS_BLOCK_GROUP_DATA)
         block->trace_leaf = true;
     else
         block->trace_leaf = false;
     btrfs_node_key_to_cpu(reloc_parent, &block->first_key, reloc_slot);
 
     /* Insert @block into @blocks */
     spin_lock(&blocks->lock);
     cur = &blocks->blocks[level].rb_node;
     while (*cur) {
         struct btrfs_qgroup_swapped_block *entry;
 
         parent = *cur;
         entry = rb_entry(parent, struct btrfs_qgroup_swapped_block,
                  node);
 
         if (entry->subvol_bytenr < block->subvol_bytenr) {
             cur = &(*cur)->rb_left;
         } else if (entry->subvol_bytenr > block->subvol_bytenr) {
             cur = &(*cur)->rb_right;
         } else {
             if (entry->subvol_generation !=
                     block->subvol_generation ||
                 entry->reloc_bytenr != block->reloc_bytenr ||
                 entry->reloc_generation !=
                     block->reloc_generation) {
                 /*
                  * Duplicated but mismatch entry found.
                  * Shouldn't happen.
                  *
                  * Marking qgroup inconsistent should be enough
                  * for end users.
                  */
                 WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
                 ret = -EEXIST;
             }
             kfree(block);
             goto out_unlock;
         }
     }
     rb_link_node(&block->node, parent, cur);
     rb_insert_color(&block->node, &blocks->blocks[level]);
     blocks->swapped = true;
 out_unlock:
     spin_unlock(&blocks->lock);
 out:
     if (ret < 0)
         fs_info->qgroup_flags |=
             BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
     return ret;
 }
 
 /*
  * Check if the tree block is a subtree root, and if so do the needed
  * delayed subtree trace for qgroup.
  *
  * This is called during btrfs_cow_block().
  */
 int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans,
                      struct btrfs_root *root,
                      struct extent_buffer *subvol_eb)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_qgroup_swapped_blocks *blocks = &root->swapped_blocks;
     struct btrfs_qgroup_swapped_block *block;
     struct extent_buffer *reloc_eb = NULL;
     struct rb_node *node;
     bool found = false;
     bool swapped = false;
     int level = btrfs_header_level(subvol_eb);
     int ret = 0;
     int i;
 
     if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
         return 0;
     if (!is_fstree(root->root_key.objectid) || !root->reloc_root)
         return 0;
 
     spin_lock(&blocks->lock);
     if (!blocks->swapped) {
         spin_unlock(&blocks->lock);
         return 0;
     }
     node = blocks->blocks[level].rb_node;
 
     while (node) {
         block = rb_entry(node, struct btrfs_qgroup_swapped_block, node);
         if (block->subvol_bytenr < subvol_eb->start) {
             node = node->rb_left;
         } else if (block->subvol_bytenr > subvol_eb->start) {
             node = node->rb_right;
         } else {
             found = true;
             break;
         }
     }
     if (!found) {
         spin_unlock(&blocks->lock);
         goto out;
     }
     /* Found one, remove it from @blocks first and update blocks->swapped */
     rb_erase(&block->node, &blocks->blocks[level]);
     for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
         if (RB_EMPTY_ROOT(&blocks->blocks[i])) {
             swapped = true;
             break;
         }
     }
     blocks->swapped = swapped;
     spin_unlock(&blocks->lock);
 
     /* Read out reloc subtree root */
     reloc_eb = read_tree_block(fs_info, block->reloc_bytenr, 0,
                    block->reloc_generation, block->level,
                    &block->first_key);
     if (IS_ERR(reloc_eb)) {
         ret = PTR_ERR(reloc_eb);
         reloc_eb = NULL;
         goto free_out;
     }
     if (!extent_buffer_uptodate(reloc_eb)) {
         ret = -EIO;
         goto free_out;
     }
 
     ret = qgroup_trace_subtree_swap(trans, reloc_eb, subvol_eb,
             block->last_snapshot, block->trace_leaf);
 free_out:
     kfree(block);
     free_extent_buffer(reloc_eb);
 out:
     if (ret < 0) {
         btrfs_err_rl(fs_info,
                  "failed to account subtree at bytenr %llu: %d",
                  subvol_eb->start, ret);
         fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
     }
     return ret;
 }
 
 void btrfs_qgroup_destroy_extent_records(struct btrfs_transaction *trans)
 {
     struct btrfs_qgroup_extent_record *entry;
     struct btrfs_qgroup_extent_record *next;
     struct rb_root *root;
 
     root = &trans->delayed_refs.dirty_extent_root;
     rbtree_postorder_for_each_entry_safe(entry, next, root, node) {
         ulist_free(entry->old_roots);
         kfree(entry);
     }
 }