Btrfs: split btrfs_qgroup_account_ref into four functions

The function is separated into a preparation part and the three accounting
steps mentioned in the qgroups documentation. The goal is to make steps two
and three usable by the rescan functionality. A side effect is that the
function is restructured into readable subunits.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 148 insertions, 105 deletions

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index e5c56238b6c6..1fb7d8da3084 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1185,6 +1185,144 @@ int btrfs_qgroup_record_ref(struct btrfs_trans_handle *trans,
         return 0;
 }
 
+static int qgroup_account_ref_step1(struct btrfs_fs_info *fs_info,
+                                    struct ulist *roots, struct ulist *tmp,
+                                    u64 seq)
+{
+        struct ulist_node *unode;
+        struct ulist_iterator uiter;
+        struct ulist_node *tmp_unode;
+        struct ulist_iterator tmp_uiter;
+        struct btrfs_qgroup *qg;
+        int ret;
+
+        ULIST_ITER_INIT(&uiter);
+        while ((unode = ulist_next(roots, &uiter))) {
+                qg = find_qgroup_rb(fs_info, unode->val);
+                if (!qg)
+                        continue;
+
+                ulist_reinit(tmp);
+                                                /* XXX id not needed */
+                ret = ulist_add(tmp, qg->qgroupid,
+                                (u64)(uintptr_t)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 = (struct btrfs_qgroup *)(uintptr_t)tmp_unode->aux;
+                        if (qg->refcnt < seq)
+                                qg->refcnt = seq + 1;
+                        else
+                                ++qg->refcnt;
+
+                        list_for_each_entry(glist, &qg->groups, next_group) {
+                                ret = ulist_add(tmp, glist->group->qgroupid,
+                                                (u64)(uintptr_t)glist->group,
+                                                GFP_ATOMIC);
+                                if (ret < 0)
+                                        return ret;
+                        }
+                }
+        }
+
+        return 0;
+}
+
+static int qgroup_account_ref_step2(struct btrfs_fs_info *fs_info,
+                                    struct ulist *roots, struct ulist *tmp,
+                                    u64 seq, int sgn, u64 num_bytes,
+                                    struct btrfs_qgroup *qgroup)
+{
+        struct ulist_node *unode;
+        struct ulist_iterator uiter;
+        struct btrfs_qgroup *qg;
+        struct btrfs_qgroup_list *glist;
+        int ret;
+
+        ulist_reinit(tmp);
+        ret = ulist_add(tmp, qgroup->qgroupid, (uintptr_t)qgroup, GFP_ATOMIC);
+        if (ret < 0)
+                return ret;
+
+        ULIST_ITER_INIT(&uiter);
+        while ((unode = ulist_next(tmp, &uiter))) {
+                qg = (struct btrfs_qgroup *)(uintptr_t)unode->aux;
+                if (qg->refcnt < seq) {
+                        /* not visited by step 1 */
+                        qg->rfer += sgn * num_bytes;
+                        qg->rfer_cmpr += sgn * num_bytes;
+                        if (roots->nnodes == 0) {
+                                qg->excl += sgn * num_bytes;
+                                qg->excl_cmpr += sgn * num_bytes;
+                        }
+                        qgroup_dirty(fs_info, qg);
+                }
+                WARN_ON(qg->tag >= seq);
+                qg->tag = seq;
+
+                list_for_each_entry(glist, &qg->groups, next_group) {
+                        ret = ulist_add(tmp, glist->group->qgroupid,
+                                        (uintptr_t)glist->group, GFP_ATOMIC);
+                        if (ret < 0)
+                                return ret;
+                }
+        }
+
+        return 0;
+}
+
+static int qgroup_account_ref_step3(struct btrfs_fs_info *fs_info,
+                                    struct ulist *roots, struct ulist *tmp,
+                                    u64 seq, int sgn, u64 num_bytes)
+{
+        struct ulist_node *unode;
+        struct ulist_iterator uiter;
+        struct btrfs_qgroup *qg;
+        struct ulist_node *tmp_unode;
+        struct ulist_iterator tmp_uiter;
+        int ret;
+
+        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(tmp, qg->qgroupid, (uintptr_t)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 = (struct btrfs_qgroup *)(uintptr_t)tmp_unode->aux;
+                        if (qg->tag == seq)
+                                continue;
+
+                        if (qg->refcnt - seq == roots->nnodes) {
+                                qg->excl -= sgn * num_bytes;
+                                qg->excl_cmpr -= sgn * num_bytes;
+                                qgroup_dirty(fs_info, qg);
+                        }
+
+                        list_for_each_entry(glist, &qg->groups, next_group) {
+                                ret = ulist_add(tmp, glist->group->qgroupid,
+                                                (uintptr_t)glist->group,
+                                                GFP_ATOMIC);
+                                if (ret < 0)
+                                        return ret;
+                        }
+                }
+        }
+
+        return 0;
+}
+
 /*
  * btrfs_qgroup_account_ref is called for every ref that is added to or deleted
  * from the fs. First, all roots referencing the extent are searched, and
@@ -1200,10 +1338,8 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans,
         struct btrfs_root *quota_root;
         u64 ref_root;
         struct btrfs_qgroup *qgroup;
-        struct ulist_node *unode;
         struct ulist *roots = NULL;
         struct ulist *tmp = NULL;
-        struct ulist_iterator uiter;
         u64 seq;
         int ret = 0;
         int sgn;
@@ -1287,119 +1423,26 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans,
         seq = fs_info->qgroup_seq;
         fs_info->qgroup_seq += roots->nnodes + 1; /* max refcnt */
 
-        ULIST_ITER_INIT(&uiter);
-        while ((unode = ulist_next(roots, &uiter))) {
-                struct ulist_node *tmp_unode;
-                struct ulist_iterator tmp_uiter;
-                struct btrfs_qgroup *qg;
-
-                qg = find_qgroup_rb(fs_info, unode->val);
-                if (!qg)
-                        continue;
-
-                ulist_reinit(tmp);
-                                                /* XXX id not needed */
-                ret = ulist_add(tmp, qg->qgroupid,
-                                (u64)(uintptr_t)qg, GFP_ATOMIC);
-                if (ret < 0)
-                        goto unlock;
-                ULIST_ITER_INIT(&tmp_uiter);
-                while ((tmp_unode = ulist_next(tmp, &tmp_uiter))) {
-                        struct btrfs_qgroup_list *glist;
-
-                        qg = (struct btrfs_qgroup *)(uintptr_t)tmp_unode->aux;
-                        if (qg->refcnt < seq)
-                                qg->refcnt = seq + 1;
-                        else
-                                ++qg->refcnt;
-
-                        list_for_each_entry(glist, &qg->groups, next_group) {
-                                ret = ulist_add(tmp, glist->group->qgroupid,
-                                                (u64)(uintptr_t)glist->group,
-                                                GFP_ATOMIC);
-                                if (ret < 0)
-                                        goto unlock;
-                        }
-                }
-        }
+        ret = qgroup_account_ref_step1(fs_info, roots, tmp, seq);
+        if (ret)
+                goto unlock;
 
         /*
          * step 2: walk from the new root
          */
-        ulist_reinit(tmp);
-        ret = ulist_add(tmp, qgroup->qgroupid,
-                        (uintptr_t)qgroup, GFP_ATOMIC);
-        if (ret < 0)
+        ret = qgroup_account_ref_step2(fs_info, roots, tmp, seq, sgn,
+                                       node->num_bytes, qgroup);
+        if (ret)
                 goto unlock;
-        ULIST_ITER_INIT(&uiter);
-        while ((unode = ulist_next(tmp, &uiter))) {
-                struct btrfs_qgroup *qg;
-                struct btrfs_qgroup_list *glist;
-
-                qg = (struct btrfs_qgroup *)(uintptr_t)unode->aux;
-                if (qg->refcnt < seq) {
-                        /* not visited by step 1 */
-                        qg->rfer += sgn * node->num_bytes;
-                        qg->rfer_cmpr += sgn * node->num_bytes;
-                        if (roots->nnodes == 0) {
-                                qg->excl += sgn * node->num_bytes;
-                                qg->excl_cmpr += sgn * node->num_bytes;
-                        }
-                        qgroup_dirty(fs_info, qg);
-                }
-                WARN_ON(qg->tag >= seq);
-                qg->tag = seq;
-
-                list_for_each_entry(glist, &qg->groups, next_group) {
-                        ret = ulist_add(tmp, glist->group->qgroupid,
-                                        (uintptr_t)glist->group, GFP_ATOMIC);
-                        if (ret < 0)
-                                goto unlock;
-                }
-        }
 
         /*
          * step 3: walk again from old refs
          */
-        ULIST_ITER_INIT(&uiter);
-        while ((unode = ulist_next(roots, &uiter))) {
-                struct btrfs_qgroup *qg;
-                struct ulist_node *tmp_unode;
-                struct ulist_iterator tmp_uiter;
-
-                qg = find_qgroup_rb(fs_info, unode->val);
-                if (!qg)
-                        continue;
-
-                ulist_reinit(tmp);
-                ret = ulist_add(tmp, qg->qgroupid,
-                                (uintptr_t)qg, GFP_ATOMIC);
-                if (ret < 0)
-                        goto unlock;
-                ULIST_ITER_INIT(&tmp_uiter);
-                while ((tmp_unode = ulist_next(tmp, &tmp_uiter))) {
-                        struct btrfs_qgroup_list *glist;
-
-                        qg = (struct btrfs_qgroup *)(uintptr_t)tmp_unode->aux;
-                        if (qg->tag == seq)
-                                continue;
-
-                        if (qg->refcnt - seq == roots->nnodes) {
-                                qg->excl -= sgn * node->num_bytes;
-                                qg->excl_cmpr -= sgn * node->num_bytes;
-                                qgroup_dirty(fs_info, qg);
-                        }
+        ret = qgroup_account_ref_step3(fs_info, roots, tmp, seq, sgn,
+                                       node->num_bytes);
+        if (ret)
+                goto unlock;
 
-                        list_for_each_entry(glist, &qg->groups, next_group) {
-                                ret = ulist_add(tmp, glist->group->qgroupid,
-                                                (uintptr_t)glist->group,
-                                                GFP_ATOMIC);
-                                if (ret < 0)
-                                        goto unlock;
-                        }
-                }
-        }
-        ret = 0;
 unlock:
         spin_unlock(&fs_info->qgroup_lock);
         ulist_free(roots);