[LU-19483] FLR-EC: Direct EC component read/write

• Type: Technical task
• Resolution: Won't Fix
• Priority: Medium
• Labels: FLR-EC FLR-EC-RO
• Severity: 3
• Assignee: Patrick Farrell
• Reporter: Patrick Farrell

Description

Implement direct read/write support for EC parity components

Add ioctls to allow user space to directly read and write erasure-coded (EC) parity data, similar to the existing designated mirror I/O functionality used for FLR. These designated EC ioctls will target parity components only and operate independently from normal data I/O.

If no mirror ID is specified, the operations default to mirror 0 and must also work for non-mirrored EC files.

This work includes kernel-side implementation of the designated EC ioctls, along with new user-space commands lfs ec read and lfs ec write to exercise the functionality.