On Tue, May 20, 2025 at 02:40:07PM +0200, Amir Goldstein wrote: > On Tue, May 20, 2025 at 2:25 PM Kent Overstreet > <kent.overstreet@xxxxxxxxx> wrote: > > > > On Tue, May 20, 2025 at 10:05:14AM +0200, Amir Goldstein wrote: > > > On Tue, May 20, 2025 at 7:16 AM Kent Overstreet > > > <kent.overstreet@xxxxxxxxx> wrote: > > > > > > > > This series allows overlayfs and casefolding to safely be used on the > > > > same filesystem by providing exclusion to ensure that overlayfs never > > > > has to deal with casefolded directories. > > > > > > > > Currently, overlayfs can't be used _at all_ if a filesystem even > > > > supports casefolding, which is really nasty for users. > > > > > > > > Components: > > > > > > > > - filesystem has to track, for each directory, "does any _descendent_ > > > > have casefolding enabled" > > > > > > > > - new inode flag to pass this to VFS layer > > > > > > > > - new dcache methods for providing refs for overlayfs, and filesystem > > > > methods for safely clearing this flag > > > > > > > > - new superblock flag for indicating to overlayfs & dcache "filesystem > > > > supports casefolding, it's safe to use provided new dcache methods are > > > > used" > > > > > > > > > > I don't think that this is really needed. > > > > > > Too bad you did not ask before going through the trouble of this implementation. > > > > > > I think it is enough for overlayfs to know the THIS directory has no > > > casefolding. > > > > overlayfs works on trees, not directories... > > I know how overlayfs works... > > I've explained why I don't think that sanitizing the entire tree is needed > for creating overlayfs over a filesystem that may enable casefolding > on some of its directories. So, you want to move error checking from mount time, where we _just_ did a massive API rework so that we can return errors in a way that users will actually see them - to open/lookup, where all we have are a small fixed set of error codes?
