[{"id":3684291,"web_url":"http://patchwork.ozlabs.org/comment/3684291/","msgid":"<3d3d6e22-b8a7-4f32-8046-697e45ec6c04@dev.snart.me>","list_archive_url":null,"date":"2026-04-29T22:00:04","subject":"Re: [PATCH v12 04/15] exfat: Implement fileattr_get for case\n sensitivity","submitter":{"id":92763,"url":"http://patchwork.ozlabs.org/api/people/92763/","name":"David Timber","email":"dxdt@dev.snart.me"},"content":"On 4/30/26 03:07, Chuck Lever wrote:\n> From: Chuck Lever \n>\n> Report exFAT's case sensitivity behavior via the FS_XFLAG_CASEFOLD\n> flag. exFAT is always case-insensitive (using an upcase table for\n> comparison) and always preserves case at rest.\nNot necessarily \"always\".\n\nLink: https://github.com/exfatprogs/exfatprogs/issues/313\n\nThe specs(SD spec part 2 and MS spec) leave it up to the formatter\nimplementation on how the volume should behave. The observed behaviour\nis that it is quite flexible: you can pretty much use any artitrary\nup-case table to make an exFAT volume behave completely different and\nmajor implementations including Linux and Windows kernel honour the\ntable no matter what. So exFAT is not so \"binary\"(folding vs. not\nfolding) when it comes to case folding behaviour.\n\nNTFS also has a similar up-case table feature. Although it's usually\nunused, if an up-case table exists in the volume, the implementation\nprobably has to honour it(although this is not written down in any spec,\nthis should be the expectation).\n\nAt the end of the day, it wouldn't matter much because no sane formatter\nwould produce a volume with some weird version up-case table. But if\nthat attribute plays a important role in some system that has some level\nof impact, I suggest considering another attribute, say \"unknown\" or \"it\ndepends\".\n\nDavo","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ext4@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=2404:9400:2221:ea00::3; helo=mail.ozlabs.org;\n envelope-from=srs0=ur1s=c4=vger.kernel.org=linux-ext4+bounces-16244-patchwork-incoming=ozlabs.org@ozlabs.org;\n receiver=patchwork.ozlabs.org)","gandalf.ozlabs.org;\n arc=pass smtp.remote-ip=\"2600:3c09:e001:a7::12fc:5321\"\n arc.chain=subspace.kernel.org","gandalf.ozlabs.org;\n dmarc=fail (p=reject dis=none) header.from=dev.snart.me","gandalf.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c09:e001:a7::12fc:5321; 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