Zstd Gets A Few Fixes For Linux 6.3 While The Big Update Delayed To v6.4

Merged last cycle was a big Zstd update for Linux 6.2 that took the kernel's Zstandard compression/decompression implementation to match that of upstream v1.5 after being stuck in the v1.4 series for more than a year. Following that, Zstd 1.5.4 was released last month. The hope was Zstd 1.5.4 would quickly follow into the mainline kernel while that is now delayed to Linux 6.4 and for the 6.3 kernel cycle seeing just a few fixes.

When Zstd 1.5 was pulled into the mainline kernel, the hope was moving forward the changes would allow the kernel's copy of Zstd to more closely track the upstream Zstd code-base. For Linux 6.3 though the Zstd 1.5.4 code isn't being submitted since it didn't have time to bake in linux-next. Thus for better test exposure and ensuring no issues, the Zstd 1.5.4 update in the kernel won't be here until Linux 6.4 this summer.

But in any event for the Zstd changes in Linux 6.3 there are at least a few fixes. There is a fix for in-place decompression, a compiler warning fix, and also fixing an assrt() logic. So not as exciting as seeing v1.5.4 pulled into the kernel so quickly, but at least the v1.5 state is better than what it was on pre-6.2 kernels and that new Zstd code will be given extra time to bake.

Zstd is increasingly used throughout the Linux kernel from file-system compression to compressing the kernel build, firmware compression, and various other data compression/decompression needs.