From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757922Ab2GKOJs (ORCPT ); Wed, 11 Jul 2012 10:09:48 -0400 Received: from fieldses.org ([174.143.236.118]:39419 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755220Ab2GKOJq (ORCPT ); Wed, 11 Jul 2012 10:09:46 -0400 Date: Wed, 11 Jul 2012 10:09:44 -0400 From: "J. Bruce Fields" To: Namjae Jeon Cc: SteveD@redhat.com, Trond.Myklebust@netapp.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Vivek Trivedi Subject: Re: [PATCH] nfs-util: Add cache_flush in mountd UMNT procedure. Message-ID: <20120711140944.GB11432@fieldses.org> References: <1341717459-7297-1-git-send-email-linkinjeon@gmail.com> <20120710145937.GA1947@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 11, 2012 at 01:10:53PM +0900, Namjae Jeon wrote: > 2012/7/10, J. Bruce Fields : > > On Sat, Jul 07, 2012 at 11:17:39PM -0400, Namjae Jeon wrote: > >> For removing storage device - user needs to safely un-mount the device > >> and then eject. But if 'EBUSY' occurs in umount then it will create > >> confusion for the user as it will mean some I/O is in progress - and > >> won't allow user to safely ejecting device. > > > Hi James. > > The one drawback is that recovering from the cache flushes might be a > > little expensive if you have a lot of exports in use. > Good point. I will look for more there is the method flush only mount entry. I don't think there's a good way to flush only one entry. Also, this isn't going to help for NFSv4 since a v4 client won't do an unmount call. > > I'm curious, since you said this was for a usb disk: are users expected > > to just unplug it (in which case--is it read only?) or do they have some > > way of unmounting before they pull the plug? > Users expected to unplug it on both read only and read/write. > And there is no way that system be prepared to know about the > intelligence when the user is going to unplug. > if the user really want to detach the device safely. There is an > option like the desktop PC - where, we can say - umount/eject the > device. There is a proper user interface for safe removal. > but they can not unplug safely if usb device is mounted with nfs > because of this issue. Ideal might be to get some way to notify nfsd when the device diseappears or the filesystem wants to unmount. I don't know how to do that. --b.