Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 27 Feb 2003 11:29:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 27 Feb 2003 11:29:54 -0500 Received: from dsl-212-144-205-077.arcor-ip.net ([212.144.205.77]:20100 "EHLO server1.intern.kubla.de") by vger.kernel.org with ESMTP id convert rfc822-to-8bit; Thu, 27 Feb 2003 11:29:52 -0500 From: Dominik Kubla To: Horst von Brand Subject: Re: About /etc/mtab and /proc/mounts Date: Thu, 27 Feb 2003 17:40:03 +0100 User-Agent: KMail/1.5 Cc: Kasper Dupont , Miles Bader , DervishD , Linux-kernel References: <200302271600.h1RG0Cdh011948@eeyore.valparaiso.cl> In-Reply-To: <200302271600.h1RG0Cdh011948@eeyore.valparaiso.cl> MIME-Version: 1.0 Content-Type: Text/Plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Description: clearsigned data Content-Disposition: inline Message-Id: <200302271740.06139.dominik@kubla.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3907 Lines: 100 On Thursday 27 February 2003 17:00, Horst von Brand wrote: > Dominik Kubla said: > > Quoting the Solaris 8 man page: > > I fail to see any significant difference to /proc/mounts (possibly > expanded). Sure, /proc is the wrong place for this kind of stuff, but... Then i suggest that you re-read the mnttab(4) man page and compare it to the Linux implementation. :-) Keep in mind that i only qouted some parts of the man page. Some thing are just details (but as we all know details do matter): [Linux] # ls -l /proc mounts lrwxrwxrwx 1 root root 11 Feb 27 17:10 /proc/mounts -> self/mounts # ls -l /proc/self/mounts -r--r--r-- 1 root root 0 Feb 27 17:11 /proc/self/mounts # wc -c /proc/self/mounts 1058 /proc/self/mounts [Solaris] # ls -l /etc/mnttab r--r--r-- 1 root 1178 Feb 25 16:26 /etc/mnttab # wc -c /etc/mnttab 1178 /etc/mnttab The snapshot feature as quoted in the man page is not present under Linux. The poll(2) feature is not implemented. The solaris mntfs also implements special ioctrls. Quoting the man page again: [...] IOCTLS The following ioctl(2) calls are supported: MNTIOC_NMOUNTS Returns the count of mounted resources in the current snapshot in the uint32_t pointed to by arg. MNTIOC_GETDEVLIST Returns an array of uint32_t's that is twice as long as the length returned by MNTIOC_NMOUNTS. Each pair of numbers is the major and minor device number for the file system at the corresponding line in the current /etc/mnttab snapshot. arg points to the memory buffer to receive the device number information. MNTIOC_SETTAG Sets a tag word into the options list for a mounted file system. A tag is a notation that will appear in the options string of a mounted file system but it is not recognized or interpreted by the file system code. arg points to a filled in mnttagdesc structure, as shown in the following example: uint_t mtd_major; /* major number for mounted fs */ uint_t mtd_minor; /* minor number for mounted fs */ char *mtd_mntpt; /* mount point of file system */ char *mtd_tag; /* tag to set/clear */ If the tag already exists then it is marked as set but not re-added. Tags can be at most MAX_MNTOPT_TAG long. MNTIOC_CLRTAG Marks a tag in the options list for a mounted file system as not set. arg points to the same structure as MNTIOC_SETTAG, which identifies the file system and tag to be cleared. [...] There is also an extended set of library functions to go along with that, eg. getmntany(3), getextmntent(3), resetmnttab(3) and hasmntopt(3). It is very helpful that one can get the time a mount happened! You can not get this kind of information on Linux, neither from /etc/mtab nor from /proc/self/mounts. getextmnttab(3) also gives easy access to the device major and minor number of the mount point. So there are quite some differences between the Linux proc file and the Solaris mntfs filesystem. If these differences justify us doing it the same way is debateable. The strongest argument i see is: It's already been done this way by one major Unix version, so why should Linux reinvent the wheel. Again. Regards, Dominik -- "What this country needs is a short, victorious war to stem the tide of revolution." (V.K. von Plehve, Russian Minister of Interior on the eve of the Russo-Japanese war.) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/