This is of interest to me (could help Samba performance a lot if file system optionally supports this), and other filesystems (cifs.ko) could trivially advertise when the underlying mount (the target volume) is case insensitive. On Wed, Jan 31, 2018 at 8:05 PM, Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxxxx> wrote: > > Case-insensitive lookups for filesystems is a recurrent topic for > filesystems, which got some attention in LSF/MM last year, during the > discussion to get free of the Android wrapfs hackery. This year, I have > been working on an approach to enable bind mount points supporting > casefolding, whose goal is to allow side-by-side lookups of > case-sensitive and case-insensitive names. This effort has a direct > benefit to the Android filesystem, which requires some racy code to do > this exactly feature, as well as other use cases for SteamOS. > > I published an early version with full UTF-8 (based on the SGI > patches) support for performing case-folding in the EXT4 filesystem, as > a RFC to the fsdev mailing list. The latest thread is here: > > https://www.spinics.net/lists/linux-ext4/msg59577.html > > Right now, I have focused on adapting the VFS to support a MS_CASEFOLD > VFS flag, which would allow bind mounts, but I am having concerns about > how to best explore the design of the dentry cache to handle multiple > entries only differing by case. I've been experimenting with multiple > approaches recently and getting live feedback from the community will be > very helpful. > > In addition, other semantics for case-insensitive lookups could be > discussed, like how to deal with invalid utf8 sequences, alternatives to > the VFS approach, should it prove itself unreliable, and how to best > adapt the dentry hashes to explore name sequences that only differ by > case and normalization. > > -- > Gabriel Krisman Bertazi -- Thanks, Steve
