Linux 7.4 Adds Opt-in Buffered IOmap Support for EXT4 File System
The Linux 7.4 kernel introduces optional buffered IOmap support for EXT4, offering improved write performance while requiring careful consideration of unsupported features.
Linux 7.4 integrates opt-in buffered IOmap support for EXT4, merged Sunday night by Ted Ts'o and led by Zhang Yi of Huawei.
The update replaces the file system driver's use of buffer heads with the kernel's IOmap framework. Large writes see the most significant speedups, while read improvements remain modest.
The feature stays off by default and requires the buffered_iomap mount option to activate. When enabled, it does not support online defragmentation, inline data, fsverity, fscrypt, non-extent inodes, or data=journal mode. If you enable the option, EXT4 falls back to the original I/O code path automatically when encountering those features.
Administrators moving to Linux 7.4 must check setups for unsupported dependencies before turning on the option. Systems using fscrypt encryption, fsverity, or journaled data mode will continue using the existing path.
The pull request also includes miscellaneous bug fixes and improvements covering fast commits, avoiding deadlocks, and preventing out-of-bound reads in corner cases involving corrupted file systems. Fast.