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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97106C433F5 for ; Mon, 13 Sep 2021 14:22:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F75560249 for ; Mon, 13 Sep 2021 14:22:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343844AbhIMOX0 (ORCPT ); Mon, 13 Sep 2021 10:23:26 -0400 Received: from ipmail04.adl3.internode.on.net ([150.101.137.10]:61523 "EHLO ipmail04.adl3.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245184AbhIMOSQ (ORCPT ); Mon, 13 Sep 2021 10:18:16 -0400 X-SMTP-MATCH: 1 IronPort-Data: =?us-ascii?q?A9a23=3Aj2aOgaIA5b6Jcb/YFE+RVZclxSXFcZb7ZxGr2?= =?us-ascii?q?PjKsXjdYENS1mEAzGpLW2yFMqnfY2v3fI8jaYWw/UpS6pTRzNEyQAJvrylhE?= =?us-ascii?q?ngTpZOdD9+UdhuvYX2efpLIQUk7tZUXY9WQcek5HyTWzvuPGuGx9SMmiclkZ?= =?us-ascii?q?VZd5NYpiUmdfCc8IMscoUsLd9AR0tYAbeeRW2thifuqyyHuEAfNNwxcawr42?= =?us-ascii?q?IrbwP9bh8kejRtD1rAIiVGni3eF/5UdJMp3yahctBIUSKEMdgKxb76rIL1UY?= =?us-ascii?q?grkExkR5tONyt4Xc6Hkrrz6ZFHezCAPAu7z314Y/XZaPqUTbZLwbW9ekSmJg?= =?us-ascii?q?so3zdxXrpyYSAE1M7fKn+gQFR5eVSdzIcWq/Zeefing75HDlxGun3zEmK01X?= =?us-ascii?q?BtsbOX04N1fH2BU8tQKJTYMcFaHhuSr0PS8UOYqm8dLBM3qOp4P/397wTzHA?= =?us-ascii?q?PIOX5/OWePJ6MVe0TN2gdpBdd7aZswEeX9sYQ7GbhlnJFgaEtQ9kf2ui325d?= =?us-ascii?q?CdXwHqcv7Y3/nKVyQVry7jFMdzJd8aMQslY2EGe4GTL4wzE7rsyXDCE4WPco?= =?us-ascii?q?jT237aJzH69AtlIfIBUP8VC2DW7rlH/wjVNPbdjncSEtw=3D=3D?= IronPort-HdrOrdr: =?us-ascii?q?A9a23=3AJngJT62OWVauaxZkU9MuyQqjBKckLtp133?= =?us-ascii?q?Aq2lEZdPWaSKylfrOV88jzsiWE7Qr5OUtQ++xoV5PrfZqxz/9ICOoqUItKPj?= =?us-ascii?q?OMhILAFugL0WKI+UyCJ8SRzIBgPOtbH5RDNA=3D=3D?= X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: =?us-ascii?q?A2DRBQBHXD9h/+hf03ZaHQEBPAEFBQE?= =?us-ascii?q?CAQkBFQmBUAKBHIIEVmyER60agXwLASMCHQ0BAgQBAYQDcIJFASU0CQ4BAgQ?= =?us-ascii?q?VAQEGAQEBAQEGBIEkhWgNhmwVQRgQBwYCHwcCXw0IAQGCbQGDBqxpgTEaAmW?= =?us-ascii?q?EaoMqgWOBECoBjX03gVVEgRUnD4Myh1uCZASJPjdudZFzjG6BLl2BKYlZkRt?= =?us-ascii?q?XLQeDLoExBguIfpQKBhQslXgDAZEJLZMFommHOmaBLjMaLoMuCUiOVBYViE+?= =?us-ascii?q?FWjQwOAIGCwEBAwmFQQEeCBOJeAEB?= Received: from unknown (HELO localhost) ([118.211.95.232]) by ipmail04.adl3.internode.on.net with ESMTP; 13 Sep 2021 23:46:38 +0930 Message-ID: Date: Mon, 13 Sep 2021 23:46:31 +0930 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux i686; rv:88.0) Gecko/20100101 Thunderbird/88.0 Content-Language: en-AU To: Alexander Viro From: Arthur Marsh Cc: linux-fsdevel@vger.kernel.org, Linux Kernel Mailing List , Arthur Marsh Subject: VFAT mounting / sharing issue after: d_path: make 'prepend()' fill up the buffer exactly on overflow Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On recent kernels a VFAT filesystem mounted on my i686 system started behaving weirdly: The /etc/fstab entry was: UUID=7417-5AFF /victoria vfat defaults,uid=65534,gid=65534,umask=000 0 2 After boot-up the filesystem had previously been mounted as: # mount|grep vic /dev/sdb6 on /victoria type vfat (rw,relatime,uid=65534,gid=65534,fmask=0000,dmask=0000,allow_utime=0022,codepage=437, iocharset=utf8,shortname=mixed,errors=remount-ro) On more recent kernels after the boot-up I saw the mount name truncated: # mount|grep vic /dev/sda6 on /vict type vfat (rw,relatime,uid=65534,gid=65534,fmask=0000,dmask=0000,allow_utime=0022,codepage=437, iocharset=utf8,shortname=mixed,errors=remount-ro) I could cd to /victoria and access the filesystem locally, but samba sharing of the filesystem failed. After a long git-bisect session I found the commit that caused it: commit b0cfcdd9b9672ea90642f33d6c0dd8516553adf2 Author: Linus Torvalds @linux-foundation.org> Date: Fri Jul 16 14:01:12 2021 -0700 d_path: make 'prepend()' fill up the buffer exactly on overflow Reverting the commit resolved the issue, including on kernel 5.15.0-rc1 I'm at a loss as to why the patch caused the problem with the reported mount name and samba sharing. Build was on i686 using gcc-11 and: make -j2 menuconfig bindeb-pkg I'm happy to supply .config and run tests. Arthur.