Comment by ajross
16 days ago
Indeed. But even so, it's mildly shocking, as struct file_operations has been one of the deepest (and most promiscuously) integrated and most conservative bits of the kernel API. This stuff dates back decades and almost never changes. And there are a lot of raw file drivers[1] still there from eras most people have forgotten about.
This is a big, big reorg even for Linux.
[1] To be fair, most of which probably don't support mapping.
Yes, that's true. However, it's a kernel-internal API, and those have never been considered stable, unlike the system call ABIs, which are mostly sacrosanct. Except for, like, uselib(). This is because pretty much all the code that calls the kernel-internal APIs is in a monorepo, so you can fix it all when you make the change.
Also, it's not that the core kernel is ceasing to provide a facility that drivers depended on; rather, it's ceasing to depend on a facility that drivers provided. But doing so involves adding this new mmap_prepare() thing, which is making the kernel depend on a new facility that drivers now must provide, I guess?