Building on the discussion in the two previous sessions on untorn (or atomic) writes, for buffered I/O and for XFS using direct I/O, Ojaswin Mujoo remotely led a session on support for the feature on ext4. That took place in the combined storage and filesystem track at the 2025 Linux Storage, Filesystem, Memory Management, and BPF Summit. Part of the support for the feature is already in the upstream kernel, with more coming. But there are still some challenges that Mujoo wanted to discuss.
在前两场关于未撕裂（或原子）写入的讨论——分别针对缓冲 I/O 和 XFS 的直接 I/O——的基础上，Ojaswin Mujoo 远程主持了一场关于在 ext4 上支持该特性的会议。该会议属于 2025 年 Linux 存储、文件系统、内存管理与 BPF 峰会中的存储与文件系统联合议题。目前部分对该特性的支持已经合并进上游内核，更多支持也在推进中。但 Mujoo 表示，仍有一些挑战需要讨论。
For ext4, a single filesystem block can be written atomically; that support was merged for 6.13, he said. There is work in progress on doing multi-block atomic writes in ext4. There are two main allocation challenges that need to be handled for multi-block, though: unaligned extents that do not match the hardware alignment requirements and ranges with mixed mappings, for example those that cover both unwritten data and hole sections.
他表示，在 ext4 中，单个文件系统块可以原子地写入，这项支持已在 Linux 6.13 中合并。目前正在进行的是对 ext4 实现多块原子写入的工作。但要实现这一点需要处理两个主要的分配挑战：一是与硬件对齐要求不一致的非对齐 extent；二是混合映射的范围，比如同时覆盖未写入数据和空洞（hole）区域的情况。
The ext4 bigalloc feature eliminates the problem with unaligned extents because
