From owner-freebsd-fs@freebsd.org  Sun Oct 29 18:28:25 2017
Return-Path: <owner-freebsd-fs@freebsd.org>
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 AFEC1E49496
 for <freebsd-fs@mailman.ysv.freebsd.org>; Sun, 29 Oct 2017 18:28:25 +0000 (UTC)
 (envelope-from mckusick@mckusick.com)
Received: from chez.mckusick.com (chez.mckusick.com [70.36.157.235])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 967113077;
 Sun, 29 Oct 2017 18:28:25 +0000 (UTC)
 (envelope-from mckusick@mckusick.com)
Received: from chez.mckusick.com (localhost [IPv6:::1])
 by chez.mckusick.com (8.15.2/8.15.2) with ESMTP id v9TIPjRE095791;
 Sun, 29 Oct 2017 11:25:45 -0700 (PDT)
 (envelope-from mckusick@chez.mckusick.com)
Message-Id: <201710291825.v9TIPjRE095791@chez.mckusick.com>
From: Kirk McKusick <mckusick@mckusick.com>
To: Stefan Esser <se@freebsd.org>
Subject: Re: softdep as a mount(8) option
cc: Mark Johnston <markj@FreeBSD.org>, freebsd-fs@FreeBSD.org
In-reply-to: <659abe72-69f9-8e89-24ba-36a9fdfb3fd5@freebsd.org>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <95789.1509301545.1@chez.mckusick.com>
Date: Sun, 29 Oct 2017 11:25:45 -0700
X-Spam-Status: No, score=-1.4 required=5.0 tests=BAYES_00,MISSING_MID,
 UNPARSEABLE_RELAY autolearn=no autolearn_force=no version=3.4.1
X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on chez.mckusick.com
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs/>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
 <mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 29 Oct 2017 18:28:25 -0000

Your patch will require some additional work now that we have
journalled soft updates. The issue is that when journalled
soft updates are in use, the FS_DOSOFTDEP flag will be set for
the filesystem as it is a prerequisite for journalling. If you
turn off the FS_DOSOFTDEP flag while journalling is enabled
very bad things will happen (hopefully just a kernel panic and
not irrecoverable filesystem state). So, additional changes are
needed to check for the FS_SUJ flag being set, and if it is, to
disallow the disabling of the FS_DOSOFTDEP flag by the mount of
the filesystem.

	Kirk McKusick