btrfs: delayed_ref: release and free qgroup reserved at proper timing

Qgroup reserved space needs to be released from inode dirty map and get
freed at different timing:

1) Release when the metadata is written into tree
After corresponding metadata is written into tree, any newer write will
be COWed(don't include NOCOW case yet).
So we must release its range from inode dirty range map, or we will
forget to reserve needed range, causing accounting exceeding the limit.

2) Free reserved bytes when delayed ref is run
When delayed refs are run, qgroup accounting will follow soon and turn
the reserved bytes into rfer/excl numbers.
As run_delayed_refs and qgroup accounting are all done at
commit_transaction() time, we are safe to free reserved space in
run_delayed_ref time().

With these timing to release/free reserved space, we should be able to
resolve the long existing qgroup reserve space leak problem.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index e05d1f6aa293..75d8e584c3e5 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2116,14 +2116,13 @@ out:
 	return ret;
 }
 
-void btrfs_qgroup_free(struct btrfs_root *root, u64 num_bytes)
+void btrfs_qgroup_free_refroot(struct btrfs_fs_info *fs_info,
+			       u64 ref_root, u64 num_bytes)
 {
 	struct btrfs_root *quota_root;
 	struct btrfs_qgroup *qgroup;
-	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct ulist_node *unode;
 	struct ulist_iterator uiter;
-	u64 ref_root = root->root_key.objectid;
 	int ret = 0;
 
 	if (!is_fstree(ref_root))