[PATCH v4 07/18] btrfs: function for recording simple quota deltas

[Boris Burkov <boris@bur.io>]

Rather than re-computing shared/exclusive ownership based on backrefs
and walking roots for implicit backrefs, simple quotas does an increment
when creating an extent and a decrement when deleting it. Add the API
for the extent item code to use to track those events.

Also add a helper function to make collecting parent qgroups in a ulist
easier for functions like this.

Signed-off-by: Boris Burkov <boris@bur.io>
---
 fs/btrfs/qgroup.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/btrfs/qgroup.h | 11 ++++++-
 2 files changed, 83 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 8e3a4ced3077..dedc532669f4 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -332,6 +332,35 @@ static int del_relation_rb(struct btrfs_fs_info *fs_info,
 	return -ENOENT;
 }
 
+static int qgroup_collect_parents(struct btrfs_qgroup *qgroup,
+				  struct ulist *ul)
+{
+	struct ulist_iterator uiter;
+	struct ulist_node *unode;
+	struct btrfs_qgroup_list *glist;
+	struct btrfs_qgroup *qg;
+	int ret = 0;
+
+	ulist_reinit(ul);
+	ret = ulist_add(ul, qgroup->qgroupid,
+			qgroup_to_aux(qgroup), GFP_ATOMIC);
+	if (ret < 0)
+		goto out;
+	ULIST_ITER_INIT(&uiter);
+	while ((unode = ulist_next(ul, &uiter))) {
+		qg = unode_aux_to_qgroup(unode);
+		list_for_each_entry(glist, &qg->groups, next_group) {
+			ret = ulist_add(ul, glist->group->qgroupid,
+					qgroup_to_aux(glist->group), GFP_ATOMIC);
+			if (ret < 0)
+				goto out;
+		}
+	}
+	ret = 0;
+out:
+	return ret;
+}
+
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
 int btrfs_verify_qgroup_counts(struct btrfs_fs_info *fs_info, u64 qgroupid,
 			       u64 rfer, u64 excl)
@@ -4535,3 +4564,47 @@ void btrfs_qgroup_destroy_extent_records(struct btrfs_transaction *trans)
 	}
 	*root = RB_ROOT;
 }
+
+int btrfs_record_simple_quota_delta(struct btrfs_fs_info *fs_info,
+				    struct btrfs_simple_quota_delta *delta)
+{
+	int ret;
+	struct ulist *ul = fs_info->qgroup_ulist;
+	struct btrfs_qgroup *qgroup;
+	struct ulist_iterator uiter;
+	struct ulist_node *unode;
+	struct btrfs_qgroup *qg;
+	u64 root = delta->root;
+	u64 num_bytes = delta->num_bytes;
+	int sign = delta->is_inc ? 1 : -1;
+
+	if (btrfs_qgroup_mode(fs_info) != BTRFS_QGROUP_MODE_SIMPLE)
+		return 0;
+
+	if (!is_fstree(root))
+		return 0;
+
+	spin_lock(&fs_info->qgroup_lock);
+	qgroup = find_qgroup_rb(fs_info, root);
+	if (!qgroup) {
+		ret = -ENOENT;
+		goto out;
+	}
+	ret = qgroup_collect_parents(qgroup, ul);
+	if (ret)
+		goto out;
+
+	ULIST_ITER_INIT(&uiter);
+	while ((unode = ulist_next(ul, &uiter))) {
+		qg = unode_aux_to_qgroup(unode);
+		qg->excl += num_bytes * sign;
+		qg->rfer += num_bytes * sign;
+		qgroup_dirty(fs_info, qg);
+	}
+
+out:
+	spin_unlock(&fs_info->qgroup_lock);
+	if (!ret && delta->rsv_bytes)
+		btrfs_qgroup_free_refroot(fs_info, root, delta->rsv_bytes, BTRFS_QGROUP_RSV_DATA);
+	return ret;
+}
diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
index d4c4d039585f..94d85b4fbebd 100644
--- a/fs/btrfs/qgroup.h
+++ b/fs/btrfs/qgroup.h
@@ -235,6 +235,14 @@ struct btrfs_qgroup {
 	struct kobject kobj;
 };
 
+struct btrfs_simple_quota_delta {
+	u64 root; /* The fstree root this delta counts against */
+	u64 num_bytes; /* The number of bytes in the extent being counted */
+	u64 rsv_bytes; /* The number of bytes reserved for this extent */
+	bool is_inc; /* Whether we are using or freeing the extent */
+	bool is_data; /* Whether the extent is data or metadata */
+};
+
 static inline u64 btrfs_qgroup_subvolid(u64 qgroupid)
 {
 	return (qgroupid & ((1ULL << BTRFS_QGROUP_LEVEL_SHIFT) - 1));
@@ -447,5 +455,6 @@ int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans,
 		struct btrfs_root *root, struct extent_buffer *eb);
 void btrfs_qgroup_destroy_extent_records(struct btrfs_transaction *trans);
 bool btrfs_check_quota_leak(struct btrfs_fs_info *fs_info);
-
+int btrfs_record_simple_quota_delta(struct btrfs_fs_info *fs_info,
+				    struct btrfs_simple_quota_delta *delta);
 #endif
-- 
2.41.0