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 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?  Then it could
act similarly to our msdosfs.  But again, I do not think that msdosfs
informs nfs server that it is case-insensitive.