From: Ted Ts'o Subject: Re: [PATCH] Attempt to sync the fsstress writes to a frozen F.S Date: Tue, 24 May 2011 17:42:23 -0400 Message-ID: <20110524214222.GF26055@thunk.org> References: <4DCA3583.7010904@canonical.com> <1305097841-2308-1-git-send-email-surbhi.palande@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: sandeen@redhat.com, jack@suse.cz, marco.stornelli@gmail.com, adilger.kernel@dilger.ca, toshi.okajima@jp.fujitsu.com, m.mizuma@jp.fujitsu.com, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Surbhi Palande Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:42014 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933674Ab1EXVmf (ORCPT ); Tue, 24 May 2011 17:42:35 -0400 Content-Disposition: inline In-Reply-To: <1305097841-2308-1-git-send-email-surbhi.palande@canonical.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, May 11, 2011 at 10:10:41AM +0300, Surbhi Palande wrote: > While the fsstress background writes are busy dirtying the page cache, if a > fsfreeze happens then the background writes should stall. A sync should then > not have any data to sync to the FS. If it does have any data to sync then > sync will cause a deadlock by holding the s_umount write semaphore and waiting > in the wait queue for the FS to thaw, whereas the F.S can never thaw without > getting the s_umount write semaphore. > > Signed-off-by: Surbhi Palande Hi Surbhi, Have you tried out Jan Kara's patches? [1/3] fs: Create __block_page_mkwrite() helper passing error values back [2/3] vfs: Block mmapped writes while the fs is frozen [3/3] ext4: Rewrite ext4_page_mkwrite() to return locked page Do these patches fix the problem you've been trying to fix with your patches? I believe they should, but I would appreciate confirmation that with these patches, you're no longer able to reproduce the problem you've been concerned about. Thanks, regards, - Ted