From owner-freebsd-current@FreeBSD.ORG Sat Jul 8 17:38:46 2006 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2432716A4DF; Sat, 8 Jul 2006 17:38:46 +0000 (UTC) (envelope-from sam@errno.com) Received: from ebb.errno.com (ebb.errno.com [69.12.149.25]) by mx1.FreeBSD.org (Postfix) with ESMTP id C547A43D58; Sat, 8 Jul 2006 17:38:45 +0000 (GMT) (envelope-from sam@errno.com) Received: from [10.0.0.248] (trouble.errno.com [10.0.0.248]) (authenticated bits=0) by ebb.errno.com (8.13.6/8.12.6) with ESMTP id k68HceAL076112 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 8 Jul 2006 10:38:41 -0700 (PDT) (envelope-from sam@errno.com) Message-ID: <44AFEDA0.7040308@errno.com> Date: Sat, 08 Jul 2006 10:38:40 -0700 From: Sam Leffler User-Agent: Thunderbird 1.5.0.2 (X11/20060508) MIME-Version: 1.0 To: Craig Rodrigues References: <20060708152801.GA3671@crodrigues.org> <44AFD7DF.8090002@errno.com> <20060708161719.GB3871@crodrigues.org> In-Reply-To: <20060708161719.GB3871@crodrigues.org> X-Enigmail-Version: 0.94.0.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: freebsd-current@freebsd.org, freebsd-arch@freebsd.org Subject: Re: [RFC] mount can figure out fstype automatically X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 08 Jul 2006 17:38:46 -0000 Craig Rodrigues wrote: > On Sat, Jul 08, 2006 at 09:05:51AM -0700, Sam Leffler wrote: >> Linux has -t auto; haven't looked at how it works. > > I didn't want to implement -t auto, in > case that would confuse things in case someone gets around > to implementing autofs for FreeBSD, so I just used -t "". Oh, I stupidly assumed "auto" meant something similar to what you were doing :) > >> It appears you just try a series of fs types; can't you read the device >> to infer the filesystem? > > I was thinking of doing something like that. You can basically > get the same info by doing something like: > > file - < /dev/ad0s1e > /dev/stdin: Unix Fast File system (little-endian) > > file - < /dev/ad0s4 > /dev/stdin: SGI XFS filesystem > > > I leaned away from this approach in mount(8) because: > - I didn't want to tie mount(8) to file(1) > - I didn't want to build up a table of known superblocks > inside mount(8) because every time a new filesystem is > added to FreeBSD, mount(8) would need to be updated > > If there was a way, maybe at the GEOM or filesystem level to > "taste" what type of filesystem existed on a device, and/or > have a filesystem advertise what type of superblock it has, > then that would be a nice way to do it, but I couldn't figure > out a way to easily do it. I wouldn't expect a program like mount to fork+exec file; I'd expect it to either read directly or use a kernel facility. Sounds like something is missing to do this right. Sam