From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3AC06C43334 for ; Mon, 18 Jul 2022 19:28:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235892AbiGRT2K (ORCPT ); Mon, 18 Jul 2022 15:28:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233716AbiGRT2J (ORCPT ); Mon, 18 Jul 2022 15:28:09 -0400 Received: from mail-ej1-x62c.google.com (mail-ej1-x62c.google.com [IPv6:2a00:1450:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DFFB62FFF3 for ; Mon, 18 Jul 2022 12:28:07 -0700 (PDT) Received: by mail-ej1-x62c.google.com with SMTP id ss3so23109622ejc.11 for ; Mon, 18 Jul 2022 12:28:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=glVmtsuU15Iaox1iZcFTntcIxvzzo12UNdGz2h5AEHU=; b=aSZgaWhEpqugDki03ICBGmsvTrcI45a/Gg144M0CC2+3qihdGYp0Dzmpkilf8GwM2T FP0uyixIPyan05aTJxgyStEzgKas9WUBCMWpIxManFkBhcYzUBWPTLcdouv6+lJwkNDX GI2kI5TVbCS0YI/Y8Zk65yubZwt2bd3k9YffY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=glVmtsuU15Iaox1iZcFTntcIxvzzo12UNdGz2h5AEHU=; b=wdotpRfPim0hdBGU+7BYV6YnwwCPCru2oOk9GZMARi6t4ht6Yppj2OqtcOrgVJN4I0 2LZyoI9cwZwase/YIhm0P7zHWUhHK92qDaKzGmoEPiZ6iSG9e3L3ecYjr32BAlFatLDT b78fEp1CtgW0+0U6dawOz4HmEIjk7QTvQBPaasbKzCotHrsPKBR643+rIO7XRg1H2nF4 5tw8OLiTcALECjRLSb6TMgI1YzVqyyypEbHYaFDTQFMHmlE6jFuynshvFpzo+QeIPAsV HX/pstMzqhGg+Y2EjkCoFXeKPM1bZW2zca1WESY1/XU57/jqS1yZ2KJ/G4pCqtks7naA zcXQ== X-Gm-Message-State: AJIora/hieU1F9nXnFUGK1cHC8cvMc/7iufAf6lzLcaBmH2t6D+H9Qo+ utPSTrY4eHtWaZB4j9upHdCd89EH6dOFgETzTHzhCg== X-Google-Smtp-Source: AGRyM1sq1MSfMyVlmKSD9wRyBuQtE1YpswvG3rNfRWhbtbaq6G1mrK8LwieWjUvcdfC4v9u29djHnNWzwEaacmnUaG8= X-Received: by 2002:a17:907:75f1:b0:72b:9e40:c1a9 with SMTP id jz17-20020a17090775f100b0072b9e40c1a9mr25166610ejc.523.1658172486510; Mon, 18 Jul 2022 12:28:06 -0700 (PDT) MIME-Version: 1.0 References: <4B9D76D5-C794-4A49-A76F-3D4C10385EE0@kohlschutter.com> <83A29F9C-1A91-4753-953A-0C98E8A9832C@kohlschutter.com> In-Reply-To: From: Miklos Szeredi Date: Mon, 18 Jul 2022 21:27:55 +0200 Message-ID: Subject: Re: [PATCH] [REGRESSION] ovl: Handle ENOSYS when fileattr support is missing in lower/upper fs To: Linus Torvalds Cc: =?UTF-8?Q?Christian_Kohlsch=C3=BCtter?= , overlayfs , linux-kernel , linux-fsdevel Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On Mon, 18 Jul 2022 at 21:17, Linus Torvalds wrote: > > On Mon, Jul 18, 2022 at 12:04 PM Christian Kohlsch=C3=BCtter > wrote: > > > > The regression in question caused overlayfs to erroneously return ENOSY= S when one lower filesystem (e.g., davfs2) returned this upon checking exte= nded attributes (there were two relevant submissions triggering this somewh= ere around 5.15, 5.16) > > Well, if that's the case, isn't the proper fix to just fix davfs2? > > If ENOSYS isn't a valid error, and has broken apps that want to just > ignore "no fattr support", then it's a davfs2 bug, and fixing it there > will presumably magically just fix the ovl case too? Libfuse returns ENOSYS for requests which the filesystem doesn't support. Hence this is not a davfs bug, davfs knows nothing about itoctls, the userspace filesystem is just returning the error value that is used to mean "no support for this type of request". So this is a bug in the kernel part of fuse, that doesn't catch and convert ENOSYS in case of the ioctl request. Fixing it in fuse should fix it in overlayfs as well, as you say. Thanks, Miklos