Linux 7.4 will bring another round of performance optimizations to the Btrfs file system, building on the larger gains that landed in Linux 7.3, which Linus Torvalds released on October 18, 2026. Btrfs maintainer David Sterba of SUSE sent the Btrfs pull request for 7.4 on October 15, and Phoronix summarized the speed-ups on October 19.
Sterba described the performance work as minor. For users who compress their file systems with Btrfs’ transparent Zstd support, the pull request lists a “minor speedup in zstd decompression (+8MB/s).”
A second change reduces contention on the inode extent map lock. According to the pull request, that helps cases such as the shrinker processing inodes that have no extent maps, with a “measured time reduction 10-20%.”
Reflinks also get faster. Sterba wrote that the locking and flushing were reordered “to optimize for more common cases where the reflinked ranges are accessed, avoid unnecessary contention.” Commits from Boris Burkov in the series pre-flush the reflink source before taking inode locks and skip the unlocked source flush when the inode has writers.
Fixes and user-visible changes
Most of the pull request is fixes and core work rather than speed. Btrfs drops its tweakable sysfs method for enabling features, which was used only for extent-irefs, a feature on by default since kernel 3.12. Sterba wrote that the sysfs interface “makes it complicated due to locking and context, unlike ioctl.”
The ‘rescue=usebackuproot’ mount option also changes which backup superblock it picks, skipping the last one because of rotation, and new usebackuproot_N options select a specific backup superblock by index. Other items include kvmalloc for b-tree buffer allocations, many qgroup fixes, error handling fixes, page-to-folio cleanups and simpler transaction state handling.
For comparison, Phoronix’s Linux 7.3 Btrfs benchmarks followed a pull request that cited roughly 3x and 5x gains in specific areas, including a switch to an iomap bounce buffer for direct I/O.
The code is tagged for-7.4-tag in Sterba’s kernel.org Git tree, based on Linux 7.3-rc7. The 7.4 merge window opened October 19, and Torvalds said in his Linux 7.3 announcement that he is on his annual family vacation and may need “an extra week of merging just to catch up.”