From owner-freebsd-fs@freebsd.org Fri Oct 27 15:39:05 2017 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 0B649E496E3 for ; Fri, 27 Oct 2017 15:39:05 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: from mail-qk0-x22c.google.com (mail-qk0-x22c.google.com [IPv6:2607:f8b0:400d:c09::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id B87B16BD53 for ; Fri, 27 Oct 2017 15:39:04 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: by mail-qk0-x22c.google.com with SMTP id m189so8813057qke.4 for ; Fri, 27 Oct 2017 08:39:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:subject:message-id:mime-version :content-disposition:user-agent; bh=reRKSJICjdTv64LuIddq2Lifq6/MWNI2hgw7sp5AvwI=; b=UaTrlO34atXg2t4bB1bHHCwnuzMOfHz4szhgiOmkQzL8TGmA31nmRUedhLr3wDYBqU POjwe2QwFCEnycaqmJp5kSFugPs7X3VWmDjuMeOOP8PXDOO2BIpCEV06c7fetcvtZN+T AcBlb1AW2FR2tyzMti53jYsBk4OqthrFtYIsMUu6epzB0BceXGqIi4oSLXV4SffxNwgg Q3aU6KfoAtGfRc8hOJKL396roPM2L3cv+O4tT/20XEV6Cd9HX5CdTvpMbw+aV7qc2H93 jYHKfF5pyQ5Um3CxxlGpjXtV1TtRfN4rGEzfxL6s83TpCH341TfZZRE05Jh7ynSmzmrJ aCGg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:subject:message-id :mime-version:content-disposition:user-agent; bh=reRKSJICjdTv64LuIddq2Lifq6/MWNI2hgw7sp5AvwI=; b=M5zCp4q5vy+4uwzWPX2NzrDUPrS1RvzCFxW2HsbxH1g55jbwrspYoRN6pMAy8IPo/v 3PlnW+4yRWtY89op+4YL1fXFTOI4vzDImz9OflKXpHZxKJ309lBV2h5oPsPT1uizBjQ4 mhRhtJ+mvQBEqumkI9cqYfBoNq8fgU4cKfK0teEGMrqQiYl2G/YKb9xeiCq7YvXeEYX+ MCr/yX0cYo/b7OjhPyER9N8cr6yxkqAbqRdfRLBQoa1DA6poS3mllXC1lp8hkQaGhMqi j6OOaZukBzJPrpwFUt3aj73w0W6BeXJ2CXFFTp1+5cBdFG4SwAyqFKe2ki7rrpQ3cT/C ry8g== X-Gm-Message-State: AMCzsaWWUsYemSKtFr/WHbhqGM2DzfRB9bgEvk2PIdcpoLlcVcJJUApU tK5mgrcTPLoedF3fh/9oCGPI9g== X-Google-Smtp-Source: ABhQp+TRyQshy6TpjLG5MKaIlfOwoMO/Qa03Jo1RiHIFWx9HKHzNAM0xIPxMkrztVguXDO6iuYu33g== X-Received: by 10.233.230.10 with SMTP id z10mr1358061qkf.8.1509118743507; Fri, 27 Oct 2017 08:39:03 -0700 (PDT) Received: from raichu (toroon0560w-lp140-01-69-159-38-22.dsl.bell.ca. [69.159.38.22]) by smtp.gmail.com with ESMTPSA id 42sm5264674qkx.27.2017.10.27.08.39.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 27 Oct 2017 08:39:02 -0700 (PDT) Sender: Mark Johnston Date: Fri, 27 Oct 2017 11:39:00 -0400 From: Mark Johnston To: freebsd-fs@FreeBSD.org Subject: softdep as a mount(8) option Message-ID: <20171027153859.GC2385@raichu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.1 (2017-09-22) X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Oct 2017 15:39:05 -0000 Hi, I'd like to finally enable the use of SU (not SU+J) on some small UFS filesystems. The fact that SU is enabled using a flag in the superblock poses a problem for me, however: the systems containing these filesystems may at any time be repurposed to run a kernel that supports SU but contains bugs[*] that render it unusable. I therefore can't persistently enable SU in these systems. I'm wondering if it would be possible to enable SU using a mount option rather than with a persistent flag. fsck_ffs conditionalizes some of its logic on whether SU is configured - is this necessary for correctness? That is, if I run fsck on an unclean filesystem that had been mounted with SU, and fsck runs as though SU hadn't been configured, what problems might arise? [*] These bugs are a result of local modifications and aren't in FreeBSD.