https://bugzilla.kernel.org/show_bug.cgi?id=207635 --- Comment #8 from Joerg M. Sigle (joerg.sigle@xxxxxxxxxx) --- Thank you all for your explanations, again. > Casefold is an 'incompat' feature, because it changes the directory format. > So if someone enables it (on-disk [...]), old kernels can't use the > filesystem at all. Might this not warrant a warning in the ext4/ext5 manpage? E.g. similar to what is there for the "ext64" feature: "Note that some older kernels and older versions of e2fsprogs will not support file systems with this ext4 feature enabled." The current text doesn't reveal this: "[casefold] is name-preserving on the disk, but it allows applications to lookup for a file in the file system using an encoding equivalent version of the file name." The required minimum versions of e2fsck, tune2fs etc. might also be mentioned. > This issue is about how the kernel treats inodes that got corrupted > to have the casefold flag set when the user didn't actually enable the > casefold feature. The ext4 feature flags have clear behavior for how > unexpected flags are handled, but the inode flags don't. I use ext2 as least common denominator for multiple OS. I use conservative settings. And still "got caught" by a new (!) disabled (!) opt-in (!) feature, with hits apparently coming out-of-the-blue, and left without (much of) a clue :-) So IMHO a system not expected to use certain bits should rather not turn the fs to r/o because of them. Or, at least, indicate the minimum e2fsck version needed for fixing. These bits could, however, still be checked very systematically: by letting tune2fs recommend (or even call?) ext2fs whenever a user is about to enable casefold support on a preexisting fs. Only then, these bits become really meaningful, the admin is ready, and ext2fs is guaranteed to be sufficiently new. Anytime afterwards, once that feature *is* enabled - any form of checking and reaction by the kernel would be perfectly fine and no bad surprise anymore. Equally ok: Revelation of the problem by regular scheduled e2fsck runs, once e2fsck has been sufficiently updated over time to recognize and handle the problem. Thanks again for your consideration & regards! Joerg -- You are receiving this mail because: You are watching the assignee of the bug.
