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See http://www.infradead.org/rpr.html On Thu, Aug 20, 2026 at 09:40:46PM +0800, Gao Xiang wrote: > Hi Christoph, > > On Tue, Aug 18, 2026 at 10:55:47PM -0700, Christoph Hellwig wrote: > > On Tue, Aug 11, 2026 at 05:07:17PM +0800, Gao Xiang wrote: > > > access on file-backed mounts (although I still don't think it is > > > necessary due to the EROFS immutable model). As the result, metadata > > > cache won't use the page cache of backing inodes anymore. > > > > > > The "managed cache" was originally used to cache physical compressed > > > data according to the current cache strategy and I/O patterns; since > > > file-backed mounts also need to access physical data for metadata > > > access, it's natural to reuse the managed cache for this too, providing > > > a unique inode for all physical data access. > > > > This look sane. Any reason to not use the meta inode unconditionally > > to simplify the code? > > I guess you meant avoid using bd_inode page cache? Yes. > I'm not sure if it simplifies a lot, also like fadvise(WILLNEED) to blkdev > can perform to bd_inode too so I think it can still have some benefits. This is actually an artefact of why using the bdev page cache is a bad idea, because it opens your metadata cache up to external modification and side channel attacks. > I think bd_inode page cache can be used for filesystems so maybe leave it > as-is for now, or maybe a follow-up work if it's really needed. That's how it has historically been done. We generally try to avoid it for newer designs.