From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760690AbYD2WPV (ORCPT ); Tue, 29 Apr 2008 18:15:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752551AbYD2WPF (ORCPT ); Tue, 29 Apr 2008 18:15:05 -0400 Received: from wf-out-1314.google.com ([209.85.200.171]:12928 "EHLO wf-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753333AbYD2WPD (ORCPT ); Tue, 29 Apr 2008 18:15:03 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=F9t4AvYMUSqJFbjcmv4e1zszjlWGmP9gsVvlQ5cfXrg6BG8VEMChGY38aW/948A10ydmrLkJUgimn11eIDCZ027SBp4eerwAgBvIx/mjl55l4fJQp7/Kc094nKDrbrdiisA+Q9xEKd1pC8M9h6nDf06GDgct/3OW1OCtD50H7wc= Message-ID: <8bd0f97a0804291515l1d7aacaek34113003c955a3e@mail.gmail.com> Date: Tue, 29 Apr 2008 18:15:01 -0400 From: "Mike Frysinger" To: "J. Bruce Fields" Subject: Re: [LTP/VFS] fcntl SETLEASE fails on ramfs/tmpfs Cc: "Andrew Morton" , "Bryan Wu" , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, willy@debian.org, viro@zeniv.linux.org.uk, uclinux-dist-devel@blackfin.uclinux.org, richterd@citi.umich.edu In-Reply-To: <20080429221107.GH26468@fieldses.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <386072610804282042y2dda4b52h927683a8a938ce1f@mail.gmail.com> <20080429135454.efebec8f.akpm@linux-foundation.org> <20080429214231.GC26468@fieldses.org> <8bd0f97a0804291501i2751d688h933508df2a4587b4@mail.gmail.com> <20080429221107.GH26468@fieldses.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 29, 2008 at 6:11 PM, J. Bruce Fields wrote: > On Tue, Apr 29, 2008 at 06:01:47PM -0400, Mike Frysinger wrote: > > On Tue, Apr 29, 2008 at 5:42 PM, J. Bruce Fields wrote: > > > The one thing I suspect is *not* a really serious problem here is the > > > reported LTP failure, since probably the only user of this is Samba, > > > which probably doesn't do a lot of tmpfs exports, and in any case it can > > > probably soldier on (if with degraded performance--how badly I don't > > > know) without getting the write lease it wants. > > > > i'm not sure i follow. the reported problem is that file locking does > > not work on tmpfs/ramfs storage. a not terribly uncommon scenario is > > to use tmpfs on /tmp (or similar location) and have file locking not > > work at all. so programs that use file locking or scripts that > > leverage the flock utility from the util-linux package break. > > There are three different mechanisms that might be called "file locks": > > - fcntl() locks, aka "posix locks", "byte-range locks": > documented in the "Advisory locking" section of fcntl(2). > - flock() locks: documented in flock(2) This is what the shell > utility from util-linux uses. > - leases, documented in the "Leases" section of fcntl(2). > > For the former two, I agree with you, applications actually depend on > them. > > The bug report, however, is for leases, which are much less widely used. > (The only users I know of are Samba and, to a lesser extent, NFSv4 > (which doesn't currently use write leases due to all these problems).) ah sorry, you're right of course ... while i investigated the issue originally, i clearly forget the details ;) -mike