XArray Tries Once Again To Get Merged Into The Mainline Linux Kernel

Going back several release cycles has been an effort to add the XArray data structure to the Linux kernel but to date that hasn't happened. It wasn't accepted for Linux 4.19 and now Matthew Wilcox -- who began this work about two years ago as a programmer at Microsoft -- is hoping Linux 4.20~5.0 will be the lucky release.

XArray as a reminder is intended to eventually replace the radix tree data structure within the Linux kernel as this new "eXtensible Array" integrates locking capabilities into its design, offers page cache improvements, doesn't require memory pre-loading, and offers other benefits to suit the current usage of the radix tree within the Linux kernel.

The proposal for Linux 4.20 is to get the XArray implementation in place while converting the kernel's page cache and memremap code to utilize it. Wilcox has dozens of other patches for converting other users of the radix tree migrated over to XArray and he intends to send them once this initial code is merged.

The initial XArray push would add around seven thousand lines of new code while dropping around four thousand existing lines of code over the span of ninety patches. Details on the XArray attempt for Linux 4.20~5.0 via this pull request.