>>>>> "Kent" == Kent Overstreet <kent.overstreet@xxxxxxxxx> writes: > On Tue, May 20, 2025 at 04:03:27PM +0200, Amir Goldstein wrote: >> On Tue, May 20, 2025 at 2:43 PM Kent Overstreet >> <kent.overstreet@xxxxxxxxx> wrote: >> > >> > 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? >> >> That's one way of putting it. >> >> Please explain the use case. >> >> When is overlayfs created over a subtree that is only partially case folded? >> Is that really so common that a mount time error justifies all the vfs >> infrastructure involved? > Amir, you've got two widely used filesystem features that conflict and > can't be used on the same filesystem. Wait, what? How many people use casefolding, on a per-directory basis? It's stupid. Unix/Linux has used case-sensitive filesystems for years. Yes, linux supports other OSes which did do casefolding, but yikes... per-directory support is just insane. It should be per-filesystem only at BEST. > That's _broken_. So? what about my cross mounting of VMS filesystems with "foo.txt;3" version control so I can go back to previous versions? Why can't I do that from my Linux systems that's mounting that VMS image? Just because it's done doesn't mean it's not dumb. > Users hate partitioning just for separate /boot and /home, having to > partition for different applications is horrible. And since overlay > fs is used under the hood by docker, and casefolding is used under > the hood for running Windows applications, this isn't something > people can predict in advance. Sure I can, I don't run windows applications to screw casefolding. :-) And I personally LIKE having a seperate /boot and /home, because it gives isolation. The world is not just single user laptops with everything all on one disk or spread across a couple of disks using LVM or RAID or all of the above. I also don't see any updates for the XFS tests, or any other filesystem tests, that actually checks and confirms this decidedly obtuse and dumb to implement idea. John
