Re: FreeBSD NFSv4.1 *CLIENT* - case insensitive filesystems supported? Re: FreeBSD NFSv4.1 client and server - case insensitive filesystems supported?

On Fri, Jan 16, 2026 at 3:47 PM Konstantin Belousov <kib@freebsd.org> wrote:
>
> On Fri, Jan 16, 2026 at 03:24:38PM -0800, Rick Macklem wrote:
> > On Fri, Jan 16, 2026 at 6:18 AM Konstantin Belousov <kostikbel@gmail.com> wrote:
> > >
> > > On Fri, Jan 16, 2026 at 05:53:56AM -0800, Rick Macklem wrote:
> > > > On Thu, Jan 15, 2026 at 11:55 PM Cedric Blancher
> > > > <cedric.blancher@gmail.com> wrote:
> > > > >
> > > > > On Mon, 12 Jan 2026 at 23:04, Rick Macklem <rick.macklem@gmail.com> wrote:
> > > > > >
> > > > > > On Mon, Jan 12, 2026 at 1:56 PM Rick Macklem <rick.macklem@gmail.com> wrote:
> > > > > > >
> > > > > > > On Mon, Jan 12, 2026 at 11:52 AM Cedric Blancher
> > > > > > > <cedric.blancher@gmail.com> wrote:
> > > > > > > >
> > > > > > > > Good evening!
> > > > > > > >
> > > > > > > > Does the FreeBSD >= 14.3 NFSv4.1 client and server support case
> > > > > > > > insensitive filesystems, e.g. exported ZFS or FAT?
> > > > > > > Greater than, as in 15.0.
> > > > > > Oops, that's 15.1->
> > > > > > (I looked and it is in stable/15, but not releng/15.0.)
> > > > > > (I work with main and the stable branches and don't keep track of when the
> > > > > > releases branch off.)
> > > > >
> > > > > What about the FreeBSD 15.x NFSv4.2 client - does it support
> > > > > case-insensitive filesystems?
> > > > I suppose. It doesn't care. If an application cares (I don't know of
> > > > one, offhand), it can check via pathconf(2) to see if the fs is
> > > > case-insensitive (the _PC_CASE_INSENSITIVE pathconf name
> > > > was added recently and will be in 15.1).
> > >
> > > If the client uses namecache, then I suppose it cares, esp. about caching
> > > the negative lookups.  Also for renames and deletes, the whole set of
> > > cached entries for the directory must be expunged.
> > Good point. I did have looking at this on my "to do" list, but forgot
> > about it. So, I suppose that the current answer is "the NFS client
> > does not handle case-insensitive file names correctly" until handling
> > of negative name caching is fixed.
> >
> > Initially, I might just disable name caching for case-insensitive file
> > systems.
> >
> > It sounds like the name caching code should have an option for
> > case-insensitive name comparison?
> > (For plain ASCII, that should be straightforward, but for non-ASCII
> > character sets?? I am not conversant with how case insensitivity is
> > handled for non-ASCII character sets. I know that ZFS has some
> > "form" options, but that's all I know?)
>
> Msdosfs is case-insensitive by MS requirements. It also has some
> complications due to long names translations to the 8.3 FAT16 format.
>
> Due to this, msdosfs does not cache -ve entries at all.  This, together
> with cache purge for the directory on rename or remove, should be enough.
> Of course, this assumes that lookup would match a dirent entry right
> WRT the case.
>
> I do not know exactly how the non-ASCII codepoints are handled by our
> msdosfs, but I am sure that we do not have unicode tables for convertion
> between cases.  In other words, we most likely do not handle them well.
>
> Does nfs client know if the server is case-insensitive?
Yes, for main (and 15.1 when it gets released).
So, I have a little while to fix it.
msdosfs and ZFS are patched to return 1 for pathconf()
for _PC_CASE_INSENSITIVE and the NFS client now
gets this info. (It only gets a boolean indicating if the
server file system is case-insensitive. It does not get any
other info like what ZFS has, below.)

ZFS appears to completely disable name caching when the
file system has normalization set to other than none (if I read
the code correctly?).
From "man zfsprops"..
normalization=none|formC|formD|formKC|formKD
(I have no idea what these mean, but I am guessing that there
is code in ZFS for these. Of course, it will CDDL'd, so it cannot
be included in the base system.)

>  Then it could
> act similarly to our msdosfs.  But again, I do not think that msdosfs
> informs nfs server that it is case-insensitive.
Yes, I think this would be sufficient for now.
(I was thinking of putting a nfs_XXX() front end for the cache_XXX()
calls. It could map names to "all lower case" for the case insensitive
case, but that only works for plain ASCII.
If there was a mount option that completely disables name caching
instead of mapping to "all lower case", that would cover the non-ASCII
case, I think?)
--> Does this sound like a reasonable plan? rick

>