Writeback for filesystems is the process of flushing the "dirty" (written) data in the page cache to storage. At the 2025 Linux Storage, Filesystem, Memory Management, and BPF Summit (LSFMM+BPF), Anuj Gupta led a combined storage and filesystem session on some work that has been done to parallelize the writeback process. Some of the performance problems that have been seen with the existing single-threaded writeback came up in a session at last year's summit, where the idea of doing writeback in parallel was discussed.
文件系统的写回（writeback）过程是将页缓存中“脏的”（已写入的）数据刷新到存储设备上。在 2025 年的 Linux 存储、文件系统、内存管理和 BPF 峰会（LSFMM+BPF）上，Anuj Gupta 主持了一个关于并行化写回处理工作的联合存储与文件系统会议。去年峰会的一场会议上提到，现有单线程写回机制存在一些性能问题，并探讨了并行写回的可行性，今年的这次会议正是对该方向工作的进一步讨论。
Gupta began by noting that Kundan Kumar, who posted the topic proposal, was supposed to be leading the session, but was unable to attend. Kumar and Gupta have both been working on a prototype for parallelizing writeback; the session was meant to gather feedback on it.
Gupta 一开始指出，提交此次议题的 Kundan Kumar 原本应主持本次会议，但因故未能出席。Kumar 和 Gupta 一直在合作开发一个并行化写回的原型，本次会议的目的就是为了收集社区对此工作的反馈意见。
Currently, writeback for buffered I/O is single-threaded, though applications are issuing multithreaded writes, which can lead to contention. The backing storage device is represented in the kernel by a BDI (struct backing_dev_info), and each BDI has a single writeback thread that processes the struct bdi_writeback embedded in it. Each bdi_writeback has a single list of inodes that need to be written back and a single delayed_work