From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Mon, 08 Jan 2007 19:52:30 -0800 (PST) Received: from smtp.osdl.org (smtp.osdl.org [65.172.181.24]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id l093qMqw005202 for ; Mon, 8 Jan 2007 19:52:23 -0800 Date: Mon, 8 Jan 2007 19:51:27 -0800 From: Andrew Morton Subject: Re: bd_mount_mutex -> bd_mount_sem (was Re: xfs_file_ioctl / xfs_freeze: BUG: warning at kernel/mutex-debug.c:80/debug_mutex_unlock()) Message-Id: <20070108195127.67fe86b8.akpm@osdl.org> In-Reply-To: <45A30E1D.4030401@sandeen.net> References: <20070104001420.GA32440@m.safari.iki.fi> <20070107213734.GS44411608@melbourne.sgi.com> <20070108110323.GA3803@m.safari.iki.fi> <45A27416.8030600@sandeen.net> <20070108234728.GC33919298@melbourne.sgi.com> <20070108161917.73a4c2c6.akpm@osdl.org> <45A30828.6000508@sandeen.net> <20070108191800.9d83ff5e.akpm@osdl.org> <45A30E1D.4030401@sandeen.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Eric Sandeen Cc: David Chinner , linux-kernel Mailing List , xfs@oss.sgi.com On Mon, 08 Jan 2007 21:38:05 -0600 Eric Sandeen wrote: > Andrew Morton wrote: > > On Mon, 08 Jan 2007 21:12:40 -0600 > > Eric Sandeen wrote: > > > >> Andrew Morton wrote: > >>> On Tue, 9 Jan 2007 10:47:28 +1100 > >>> David Chinner wrote: > >>> > >>>> On Mon, Jan 08, 2007 at 10:40:54AM -0600, Eric Sandeen wrote: > >>>>> Sami Farin wrote: > >>>>>> On Mon, Jan 08, 2007 at 08:37:34 +1100, David Chinner wrote: > >>>>>> ... > >>>>>>>> fstab was there just fine after -u. > >>>>>>> Oh, that still hasn't been fixed? > >>>>>> Looked like it =) > >>>>> Hm, it was proposed upstream a while ago: > >>>>> > >>>>> http://lkml.org/lkml/2006/9/27/137 > >>>>> > >>>>> I guess it got lost? > >>>> Seems like it. Andrew, did this ever get queued for merge? > >>> Seems not. I think people were hoping that various nasties in there > >>> would go away. We return to userspace with a kernel lock held?? > >> Is a semaphore any worse than the current mutex in this respect? At > >> least unlocking from another thread doesn't violate semaphore rules. :) > > > > I assume that if we weren't returning to userspace with a lock held, this > > mutex problem would simply go away. > > > > Well nobody's asserting that the filesystem must always be locked & > unlocked by the same thread, are they? That'd be a strange rule to > enforce upon the userspace doing the filesystem management wouldn't it? > Or am I thinking about this wrong... I don't even know what code we're talking about here... I'm under the impression that XFS will return to userspace with a filesystem lock held, under the expectation (ie: requirement) that userspace will later come in and release that lock. If that's not true, then what _is_ happening in there? If that _is_ true then, well, that sucks a bit.