Network File System (NFS) is commonly used in cloud environments as a cost-effective file storage solution that is easy to set up. However, the multi-tenant nature of cloud infrastructures makes distributed file systems prone to instability and unpredictability. These performance issues can be very harmful to both Cloud Service Providers (CSPs) and tenants. Therefore, CSPs and their customers require more and more real-time granular metrics (per-file, high-frequency) for dynamically optimizing data placement, resource usage and ensuring file access performance as well as for provisioning resources cost-effectively, billing and troubleshooting them rapidly. In this paper, we propose TrackIops, a novel NFS tracer that provides these metrics without effort and at low cost. TrackIops is an eBPF-based client-side requestoriented tracing solution. The main contribution of this paper is a smart kernel-level solution that reconstructs NFS request and response threads and analyses them online without requiring server instrumentation. TrackIops provides real-time per-tenant, per-file, per-second NFS metrics extractor, easy to integrate in any optimization or troubleshooting solution, with an overhead lower than 3.5% on the client in a worst-case scenario.