Advancing Data Integrity in Linux

Standalone hardware-only or software-only methods fail to provide comprehensive coverage in detecting data corruption. End-to-end data protection (E2EDP) addresses this by carrying per-block protection information (PI) throughout the I/O stack, from the application through the system software to the storage device. Although devices have supported PI for more than a decade, Linux remains incomplete in its support and utilization of these capabilities.

This paper closes two fundamental gaps in the mainline Linux kernel and introduces a PI-aware filesystem design with implementation and evaluation. First, we add a new io_uring interface that allows applications to exchange integrity metadata alongside the data. Second, we add flexible PI placement in Linux's block-integrity enabling support for a device configuration that was otherwise rejected. Finally, we introduce Filesystem Protection Information (FS-PI), a PI-aware design direction in which filesystems generate and verify integrity metadata directly while leveraging PI-capable hardware. We implement FS-PI in two major filesystems: in XFS, FS-PI introduces native data checksumming, extending data-integrity guarantees for the first time; in BTRFS, FS-PI replaces the checksum tree with a lightweight path that reduces metadata traffic, write amplification, and device wear.

We evaluated the cost and gains of FS-PI in BTRFS and XFS. The evaluation shows that FS-PI improves BTRFS performance by 26%, reduces host CPU utilization by 58%, and reduces device writes by 52%, extending SSD lifetime by 23%.