Linux 7.2-rc7 is restoring the Btrfs COW fixup worker infrastructure that was dropped during the 7.2 merge window. Without this mechanism, dirty pages without an ordered extent go undetected, leading to silent data loss. SUSE's David Sterba submitted a pull request bringing back 600+ lines of code, including folio API port and subpage block size support. Linus Torvalds has already merged it into Linux Git. A separate Btrfs pull also landed fixes for an encoded ioctl write leak, disabled large folios on highmem systems, and disabled block size greater than page size on systems without THP support.
Questions this post answers
Why was the Btrfs COW fixup worker removed in Linux 7.2 and what are the consequences?
The Btrfs COW fixup worker was dropped during the Linux 7.2 merge window, removing the mechanism that detects pages/folios marked dirty without filesystem knowledge and applies COW fixup. Without it, such pages go unhandled, resulting in silent data loss. The restored code is 600+ lines and includes folio API port and subpage block size support not present in the original fixup worker. Developers tracking Btrfs stability and kernel data-integrity issues follow kernel cycle changes like this on daily.dev.
What other Btrfs fixes landed in Linux 7.2-rc7 alongside the fixup worker restoration?
A separate Btrfs pull request for Linux 7.2-rc7 fixed a leak in the encoded ioctl write path, disabled large folios on systems with highmem, and disabled block size greater than page size support on systems without transparent hugepage (THP) support. Engineers maintaining Btrfs deployments can track patch details and regression fixes like these on daily.dev.