From: Theodore Tso Subject: Re: [PATCH, RFC] add fsck to util-linux Date: Wed, 26 Sep 2007 20:16:27 -0400 Message-ID: <20070927001627.GA18346@thunk.org> References: <20070925153735.GA26693@infradead.org> <20070926105946.GB429@thunk.org> <20070926120533.GA15894@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: util-linux-ng-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Christoph Hellwig Return-path: Content-Disposition: inline In-Reply-To: <20070926120533.GA15894-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> Sender: util-linux-ng-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org On Wed, Sep 26, 2007 at 01:05:33PM +0100, Christoph Hellwig wrote: > - make mount/fsck use libvolume_id unconditionally for detecting the > filesystem type. There's absolute no reason to use anything in > libblkid for this, and caching the result doesn't help us at all > as we're going to touch the disk anyway as part of the mount/fsck. > - make libblkid use libvolume_id internally for filesystem detection No, that's not true, since on a non-udev system (and there are those, including a number of kernel hackers, who don't use udev for a number of reasons --- like not trusting the sysfs/udev breakages, and who want a static /dev) you need an efficient way to do lookup by UUID or by LABEL without needing to search every single device. If you have a some large storage box with 30,000 LUN's, you don't want to search them all at boot time, whether you are using udev, especially if you are only mounting a small subset of the images on demand. So there will be circumstances where you really will want to use the cache, and *not* want to use /dev/disk/by-* as the lookup mechanism. - Ted