On Tue, Jan 13, 2026 at 11:02 AM Darrick J. Wong <[email protected]> wrote: > > On Mon, Jan 12, 2026 at 12:46:21PM -0500, Chuck Lever wrote: > > From: Chuck Lever <[email protected]> > > > > Upper layers such as NFSD need to query whether a filesystem is > > case-sensitive. Populate the case_insensitive and case_preserving > > fields in xfs_fileattr_get(). XFS always preserves case. XFS is > > case-sensitive by default, but supports ASCII case-insensitive > > lookups when formatted with the ASCIICI feature flag. > > > > Signed-off-by: Chuck Lever <[email protected]> > > Well as a pure binary statement of xfs' capabilities, this is correct so: > Reviewed-by: "Darrick J. Wong" <[email protected]> > > [add ngompa] > > But the next obvious question I would have as a userspace programmer is > "case insensitive how, exactly?", which was the topic of the previous > revision. Somewhere out there there's a program / emulation layer that > will want to know the exact transformation when doing a non-memcmp > lookup. Probably Winderz casefolding has behaved differently every > release since the start of NTFS, etc. >
NTFS itself is case preserving and has a namespace for Win32k entries (case-insensitive) and SFU/SUA/LXSS entries (case-sensitive). I'm not entirely certain of the nature of *how* those entries are managed, but I *believe* it's from the personalities themselves. > I don't know how to solve that, other than the fs compiles its > case-flattening code into a bpf program and exports that where someone > can read() it and run/analyze/reverse engineer it. But ugh, Linus is > right that this area is a mess. :/ > The biggie is that it has to be NLS aware. That's where it gets complicated since there are different case rules for different languages. -- 真実はいつも一つ！/ Always, there's only one truth! _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
