Re: LInux NFSv4.1 client and server- case insensitive filesystems supported?

Christoph Hellwig
2025-06-09T05:57:35Z

On Sat, Jun 07, 2025 at 02:30:37PM -0400, Chuck Lever wrote:
> Until very recently, the Linux dentry cache supported only case-
> sensitive file name lookups, and all of the file systems that NFSD is
> regularly tested with are case-preserving.

Linux has supported case insensitive file system since 1992 when Werner
added the original msdos FAT support, i.e. it exists much longer than
the dcache or knfsd.

Specific support for dealing with case insensitive in the dcache instead
working around it was added in 2008 for the case insensitive XFS
directories in 2008:

commit 9403540c0653122ca34884a180439ddbfcbcb524
Author: Barry Naujok <bnaujok@sgi.com>
Date: Wed May 21 16:50:46 2008 +1000

dcache: Add case-insensitive support d_ci_add() routine

That being said no one ever intended any of these to be exported over
NFS, and I also question the sanity of anyone wanting to use case
insensitive file systems over NFS.