[$] Filesystem testing for stable kernels

Leah Rumancik led a filesystem-track session atthe 2024 Linux Storage,Filesystem, Memory Management, and BPF Summit on the testing needed toqualify XFS patches for the stable kernels. At last year's summit,Rumancik, Amir Goldstein, and Chandan Babu Rajendra presented on their efforts to test andbackport fixes for the XFS filesystem to three separate stable kernels.There has been some longstanding unhappiness inthe XFS-development communitywith the stable-kernel process, which led tobackports ceasing for that filesystem until Goldstein started working on XFS testing for the stabletrees a few years ago. In this year's session, Rumancik updatedattendees on how things had gone over the last year and wanted to discuss someremaining pain points for the process.