EROFS, exFAT & EXT4 File-System Updates Arrive For Linux 5.19

In addition to the buttery Btrfs feature updates for the in-development Linux 5.19 kernel, the exFAT, EXT4, and EROFS file-system changes have all landed too so far in the first few days of the v5.19 merge window.

The EXT4, exFAT, and EROFS file-system work this cycle ranges from bug fixes to some interesting feature work.

The exFAT updates for that Microsoft file-system include fixes and two items worth mentioning. A Sony engineer contributed a roughly 73% performance improvement when dealing with zeroing a cluster by reducing the number of block requests. This is a big improvement for exFAT.

The other exFAT change worth mentioning in Linux 5.19 is the new "sys_tz" mount option. This is for using the system timezone as the time offset when dealing with exFAT timestamps that are treated as a UTC offset to the current local time.

Next up there are EROFS updates for that read-only Linux file-system used by some Android devices and originally developed by Huawei. The big change for EROFS with Linux 5.19 is on-demand loading for EROFS with the FSCACHE/CacheFiles infrastructure. This introduces a new file-based back-end and other improvements. See the aforelinked Git merge for all the details.

Besides EROFS now supporting on-demand load support over FSCACHE, with Linux 5.19 is now also having support for IDMAPPED mounts, support for NFS export, and various fixes.

EXT4 updates are focused on various bug fixes and clean-ups. Bug fixes include items found via different fuzzers and error injection tools. Overall a relatively light cycle for this widely-used Linux file-system.