From: Christoph Hellwig Subject: Re: [PATCHSET v3.1 0/7] data integrity: Stabilize pages during writeback for various fses Date: Tue, 10 May 2011 13:03:39 -0400 Message-ID: <20110510170339.GA27538@infradead.org> References: <20110509230318.19566.66202.stgit@elm3c44.beaverton.ibm.com> <87tyd31fkc.fsf@devron.myhome.or.jp> <20110510133603.GA5823@infradead.org> <874o524q9h.fsf@devron.myhome.or.jp> <20110510144939.GI4402@quack.suse.cz> <87aaeur31x.fsf@devron.myhome.or.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , Christoph Hellwig , "Darrick J. Wong" , Theodore Tso , Alexander Viro , Jens Axboe , "Martin K. Petersen" , Jeff Layton , Dave Chinner , linux-kernel , Dave Hansen , linux-mm@kvack.org, Chris Mason , Joel Becker , linux-scsi , linux-fsdevel , linux-ext4@vger.kernel.org, Mingming Cao To: OGAWA Hirofumi Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:40446 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751688Ab1EJRDt (ORCPT ); Tue, 10 May 2011 13:03:49 -0400 Content-Disposition: inline In-Reply-To: <87aaeur31x.fsf@devron.myhome.or.jp> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, May 11, 2011 at 12:24:58AM +0900, OGAWA Hirofumi wrote: > > under writeback and when it's freed no writeback is started. > > Sure for data -> data reallocated case. metadata -> data/metadata is > still there. That's usually handled differently. For XFS take a look at the xfs_alloc_busy_* function. For 2.6.40 they've been mostly rewritten to rarely wait for the reuse but instead avoid busy blocks. But that's a real data integrity issue even without stable pages for I/O.