From: Andi Kleen Subject: Re: [PATCH] [3/18] BKL-removal: Convert ext3 to use unlocked_ioctl Date: Mon, 28 Jan 2008 07:02:15 +0100 Message-ID: <200801280702.15484.ak@suse.de> References: <20080127317.043953000@suse.de> <20080127021709.55F0814D2E@wotan.suse.de> <20080127213347.5bf5c324.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: sct@redhat.com, adilger@clusterfs.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "linux-ext4@vger.kernel.org" To: Andrew Morton Return-path: Received: from ns2.suse.de ([195.135.220.15]:60598 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750802AbYA1GDw (ORCPT ); Mon, 28 Jan 2008 01:03:52 -0500 In-Reply-To: <20080127213347.5bf5c324.akpm@linux-foundation.org> Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: On Monday 28 January 2008 06:33, Andrew Morton wrote: > On Sun, 27 Jan 2008 03:17:09 +0100 (CET) Andi Kleen wrote: > > I checked ext3_ioctl and it looked largely safe to not be used > > without BKL. So convert it over to unlocked_ioctl. > > > > The only case where I wasn't quite sure was for the > > dynamic fs grow ioctls versus umounting -- I kept the BKL for those. > > Please cpoy linux-ext4 on ext2/3/4 material. Ok I'll resubmit those to tytso/ext4-devel (or perhaps he has already seen them) > > I skippped a lot of these patches because I just got bored of fixing > rejects. Now is a very optimistic time to be raising patches against > mainline. JFS and CIFS are already taken care of by the maintainers. This leaves remote_llseek which touches a couple of file systems. Could you perhaps take that one only please? And perhaps Nick's minix patchkit which looks safe to me and is unlikely to cause conflicts. > > + /* AK: not sure the BKL is needed, but this might prevent > > + * races against umount */ > > + lock_kernel(); > > err = ext3_group_add(sb, &input); > > journal_lock_updates(EXT3_SB(sb)->s_journal); > > journal_flush(EXT3_SB(sb)->s_journal); > > journal_unlock_updates(EXT3_SB(sb)->s_journal); > > + unlock_kernel(); > > The ext3_ioctl() caller has an open fd against the fs - should be > sufficient to keep unmount away? True. I am still conservative because group_add is a lot of code which I didn't fully check. But with the open fd it's likely safe to not take the BKL because there is nothing else (except readdir?) in ext* that takes it. > It's all reached the stage of stupid. I'll resubmit ->fasync_unlocked against -mm. Also I wanted to recheck the ->f_flags locking. I found one bug in those already and I can extract the bug fix for that one. -Andi