On Wed, Jan 19, 2022 at 09:18:05AM +0000, David Howells wrote: > The flag cannot just be dropped - it's an important part of the interaction > with cachefilesd with regard to culling. Culling to free up space is > offloaded to userspace rather than being done within the kernel. > > Previously, cachefiles, the kernel module, had to maintain a huge tree of > records of every backing inode that it was currently using so that it could > forbid cachefilesd to cull one when cachefilesd asked. I've reduced that to a > single bit flag on the inode struct, thereby saving both memory and time. You > can argue whether it's worth sacrificing an inode flag bit for that, but the > flag can be reused for any other kernel service that wants to similarly mark > an inode in use. Which is a horrible interface. But you tricked Linus into merging this crap, so let's not pretent it is a "kernel file". We have plenty of those, basically every caller of filp_open is one. It is something like "pinned for fscache/cachefiles", so name it that way and add a big fat comment expaining the atrocities.
