If you can truncate() an existing file (via 'echo > big_file.img' or similar), I would hope the filesystem could deallocate the relevant extents without requiri

If you can truncate() an existing file (via 'echo > big_file.img' or similar), I would hope the filesystem could deallocate the relevant extents without requiring more space. Seems a bit like a filesystem defect not to reserve enough space to recover from this condition with unlink().