btrfs: qgroup: use qgroup_iterator to replace tmp ulist in qgroup_update_refcnt()

For function qgroup_update_refcnt(), we use @tmp list to iterate all the
involved qgroups of a subvolume.

It's a perfect match for qgroup_iterator facility, as that @tmp ulist
has a very limited lifespan (just inside the while() loop).

By migrating to qgroup_iterator, we can get rid of the GFP_ATOMIC memory
allocation and no error handling is needed.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index a0bf8e6a8b1f2be16086767585a034c0cf3c0837..9645becee73b489c9d3f67766353268727bcbdd3 100644 (file)
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2423,13 +2423,11 @@ out:
  * 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 *roots, 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;
 
@@ -2437,40 +2435,35 @@ static int qgroup_update_refcnt(struct btrfs_fs_info *fs_info,
                return 0;
        ULIST_ITER_INIT(&uiter);
        while ((unode = ulist_next(roots, &uiter))) {
+               LIST_HEAD(tmp);
+
                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))) {
+               qgroup_iterator_add(&tmp, qg);
+               list_for_each_entry(qg, &tmp, iterator) {
                        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;
+                               qgroup_iterator_add(&tmp, glist->group);
                        }
                }
+               qgroup_iterator_clean(&tmp);
        }
        return 0;
 }
@@ -2635,7 +2628,6 @@ int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
 {
        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;
@@ -2674,12 +2666,6 @@ int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
                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) {
@@ -2694,14 +2680,12 @@ int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
        seq = fs_info->qgroup_seq;
 
        /* Update old refcnts using old_roots */
-       ret = qgroup_update_refcnt(fs_info, old_roots, tmp, qgroups, seq,
-                                  UPDATE_OLD);
+       ret = qgroup_update_refcnt(fs_info, old_roots, 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);
+       ret = qgroup_update_refcnt(fs_info, new_roots, qgroups, seq, UPDATE_NEW);
        if (ret < 0)
                goto out;
 
@@ -2715,7 +2699,6 @@ int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
 out:
        spin_unlock(&fs_info->qgroup_lock);
 out_free:
-       ulist_free(tmp);
        ulist_free(qgroups);
        ulist_free(old_roots);
        ulist_free(new_roots);