From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262106AbUKPTQe (ORCPT ); Tue, 16 Nov 2004 14:16:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262100AbUKPTOd (ORCPT ); Tue, 16 Nov 2004 14:14:33 -0500 Received: from fw.osdl.org ([65.172.181.6]:40685 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S262097AbUKPTNh (ORCPT ); Tue, 16 Nov 2004 14:13:37 -0500 Date: Tue, 16 Nov 2004 11:13:21 -0800 From: Andrew Morton To: Robin Holt Cc: holt@sgi.com, linux-kernel@vger.kernel.org, dev@sw.ru, wli@holomorphy.com, steiner@sgi.com, sandeen@sgi.com Subject: Re: 21 million inodes is causing severe pauses. Message-Id: <20041116111321.36a6cd06.akpm@osdl.org> In-Reply-To: <20041116162859.GA5594@lnx-holt.americas.sgi.com> References: <20041115195551.GA15380@lnx-holt.americas.sgi.com> <20041115145714.3f757012.akpm@osdl.org> <20041116162859.GA5594@lnx-holt.americas.sgi.com> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Robin Holt wrote: > > I guess I am very concerned at this point. If I can do a > release/reacquire, why not just change generic_shutdown_super() so the > lock_kernel() does not happen until the first pass has occurred. ie: > > --- super.c.orig 2004-11-16 10:22:17 -06:00 > +++ super.c 2004-11-16 10:22:41 -06:00 > @@ -232,10 +232,10 @@ > dput(root); > fsync_super(sb); > lock_super(sb); > - lock_kernel(); > sb->s_flags &= ~MS_ACTIVE; > /* bad name - it should be evict_inodes() */ > invalidate_inodes(sb); > + lock_kernel(); > > if (sop->write_super && sb->s_dirt) > sop->write_super(sb); > > This at least makes the lock_kernel time much smaller than it is right > now. It also does not affect any callers that may really need the BKL. lock_kernel() is also taken way up in do_umount(), hence the need for release_kernel_lock()/reacquire_kernel_lock(). > > I guess I am really asking for an indication of what the BKL is supposed > to be protecting. I have not dug for the intent down the VFS code paths > at all. It's not protecting anything around invalidate_inodes(). There may be other things in the higher-level umount path which need it.