Making the filesystem-wide cache invalidation lightspeed in FUSE

One interesting aspect of FUSE user-space file systems is that caching can be handled at the kernel level. For example, if an application reads data from a file that happens to be on a FUSE file system, the kernel will keep that data in the page cache so that later, if that data is requested again, it will be readily available, without the need for the kernel to request it again to the FUSE server. But the kernel also caches other file system data. For example, it keeps track of metadata (file size, timestamps, etc) that may allow it to also reply to a stat(2) system call without requesting it from user-space.

FUSE over io_uring

Over the past few months I had the chance to spend some time looking at an interesting new FUSE feature. This feature, merged into the Linux kernel 6.14 release, has introduced the ability to perform the communication between the user-space server (or FUSE server) and the kernel using io_uring. This means that file systems implemented in user-space will get a performance improvement simply by enabling this new feature.

Initial post and introduction

Here it is, finally! After many years of using this camandro.org domain, I've decided it was time to use it for something else other than email.