From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q3GGGNEN227724 for ; Mon, 16 Apr 2012 11:16:23 -0500 Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) by cuda.sgi.com with ESMTP id VjnVtawguXw2r7Lc (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Mon, 16 Apr 2012 09:16:22 -0700 (PDT) Date: Mon, 16 Apr 2012 18:16:20 +0200 From: Jan Kara Subject: Re: [PATCH 00/19 v5] Fix filesystem freezing deadlocks Message-ID: <20120416161620.GC6852@quack.suse.cz> References: <1334592845-22862-1-git-send-email-jack@suse.cz> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1334592845-22862-1-git-send-email-jack@suse.cz> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Al Viro Cc: Jan Kara , "J. Bruce Fields" , KONISHI Ryusuke , OGAWA Hirofumi , linux-nilfs@vger.kernel.org, Miklos Szeredi , cluster-devel@redhat.com, Anton Altaparmakov , linux-ext4@vger.kernel.org, fuse-devel@lists.sourceforge.net, Mark Fasheh , xfs@oss.sgi.com, Ben Myers , Joel Becker , dchinner@redhat.com, Steven Whitehouse , Chris Mason , linux-nfs@vger.kernel.org, Alex Elder , Theodore Ts'o , linux-ntfs-dev@lists.sourceforge.net, LKML , ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, "David S. Miller" , linux-btrfs@vger.kernel.org The subject should have been [PATCH 00/27]... Sorry for the mistake. Honza On Mon 16-04-12 18:13:38, Jan Kara wrote: > Hello, > > here is the fifth iteration of my patches to improve filesystem freezing. > No serious changes since last time. Mostly I rebased patches and merged this > series with series moving file_update_time() to ->page_mkwrite() to simplify > testing and merging. > > Filesystem freezing is currently racy and thus we can end up with dirty data on > frozen filesystem (see changelog patch 13 for detailed race description). This > patch series aims at fixing this. > > To be able to block all places where inodes get dirtied, I've moved filesystem > file_update_time() call to ->page_mkwrite callback (patches 01-07) and put > freeze handling in mnt_want_write() / mnt_drop_write(). That however required > some code shuffling and changes to kern_path_create() (see patches 09-12). I > think the result is OK but opinions may differ ;). The advantage of this change > also is that all filesystems get freeze protection almost for free - even ext2 > can handle freezing well now. > > Another potential contention point might be patch 19. In that patch we make > freeze_super() refuse to freeze the filesystem when there are open but unlinked > files which may be impractical in some cases. The main reason for this is the > problem with handling of file deletion from fput() called with mmap_sem held > (e.g. from munmap(2)), and then there's the fact that we cannot really force > such filesystem into a consistent state... But if people think that freezing > with open but unlinked files should happen, then I have some possible > solutions in mind (maybe as a separate patchset since this is large enough). > > I'm not able to hit any deadlocks, lockdep warnings, or dirty data on frozen > filesystem despite beating it with fsstress and bash-shared-mapping while > freezing and unfreezing for several hours (using ext4 and xfs) so I'm > reasonably confident this could finally be the right solution. > > Changes since v4: > * added a couple of Acked-by's > * added some comments & doc update > * added patches from series "Push file_update_time() into .page_mkwrite" > since it doesn't make much sense to keep them separate anymore > * rebased on top of 3.4-rc2 > > Changes since v3: > * added third level of freezing for fs internal purposes - hooked some > filesystems to use it (XFS, nilfs2) > * removed racy i_size check from filemap_mkwrite() > > Changes since v2: > * completely rewritten > * freezing is now blocked at VFS entry points > * two stage freezing to handle both mmapped writes and other IO > > The biggest changes since v1: > * have two counters to provide safe state transitions for SB_FREEZE_WRITE > and SB_FREEZE_TRANS states > * use percpu counters instead of own percpu structure > * added documentation fixes from the old fs freezing series > * converted XFS to use SB_FREEZE_TRANS counter instead of its private > m_active_trans counter > > Honza > > CC: Alex Elder > CC: Anton Altaparmakov > CC: Ben Myers > CC: Chris Mason > CC: cluster-devel@redhat.com > CC: "David S. Miller" > CC: fuse-devel@lists.sourceforge.net > CC: "J. Bruce Fields" > CC: Joel Becker > CC: KONISHI Ryusuke > CC: linux-btrfs@vger.kernel.org > CC: linux-ext4@vger.kernel.org > CC: linux-nfs@vger.kernel.org > CC: linux-nilfs@vger.kernel.org > CC: linux-ntfs-dev@lists.sourceforge.net > CC: Mark Fasheh > CC: Miklos Szeredi > CC: ocfs2-devel@oss.oracle.com > CC: OGAWA Hirofumi > CC: Steven Whitehouse > CC: "Theodore Ts'o" > CC: xfs@oss.sgi.com -- Jan Kara SUSE Labs, CR _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs