btrfs: qgroup: Add new qgroup calculation function

btrfs_qgroup_account_extents().

The new btrfs_qgroup_account_extents() function should be called in
btrfs_commit_transaction() and it will update all the qgroup according
to delayed_ref_root->dirty_extent_root.

The new function can handle both normal operation during
commit_transaction() or in rescan in a unified method with clearer
logic.

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

fs/btrfs/qgroup.h

@@ -103,6 +103,8 @@ int btrfs_qgroup_prepare_account_extents(struct btrfs_trans_handle *trans,
 struct btrfs_qgroup_extent_record
 *btrfs_qgroup_insert_dirty_extent(struct btrfs_delayed_ref_root *delayed_refs,
 				  struct btrfs_qgroup_extent_record *record);
+int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans,
+				 struct btrfs_fs_info *fs_info);
 int btrfs_delayed_qgroup_accounting(struct btrfs_trans_handle *trans,
 				    struct btrfs_fs_info *fs_info);
 void btrfs_remove_qgroup_operation(struct btrfs_trans_handle *trans,