From: Jan Kara Subject: Re: [RFC][PATCH] set_page_buffer_dirty should skip unmapped buffers Date: Fri, 8 Sep 2006 10:25:32 +0200 Message-ID: <20060908082531.GA28397@atrey.karlin.mff.cuni.cz> References: <20060906124719.GA11868@atrey.karlin.mff.cuni.cz> <1157555559.23501.25.camel@dyn9047017100.beaverton.ibm.com> <20060906153449.GC18281@atrey.karlin.mff.cuni.cz> <1157559545.23501.30.camel@dyn9047017100.beaverton.ibm.com> <20060906162723.GA14345@atrey.karlin.mff.cuni.cz> <1157563016.23501.39.camel@dyn9047017100.beaverton.ibm.com> <20060906172733.GC14345@atrey.karlin.mff.cuni.cz> <1157641877.7725.13.camel@dyn9047017100.beaverton.ibm.com> <20060907223048.GD22549@atrey.karlin.mff.cuni.cz> <4500F2B2.4010204@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Anton Altaparmakov , sct@redhat.com, linux-fsdevel , lkml , ext4 Return-path: To: Badari Pulavarty Content-Disposition: inline In-Reply-To: <4500F2B2.4010204@us.ibm.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Hi, > Jan Kara wrote: > > I've been looking more at the code and I have revived my patch fixing > >this part of the code. I've mildly tested the patch. Could you also give > >it a try? Thanks. > > > > Honza > > > >------------------------------------------------------------------------ > > > >Original commit code assumes, that when a buffer on BJ_SyncData list is > >locked, > >it is being written to disk. But this is not true and hence it can lead to > >a > >potential data loss on crash. Also the code didn't count with the fact that > >journal_dirty_data() can steal buffers from committing transaction and > >hence > >could write buffers that no longer belong to the committing transaction. > >Finally it could possibly happen that we tried writing out one buffer > >several > >times. > > > >The patch below tries to solve these problems by a complete rewrite of the > >data > >commit code. We go through buffers on t_sync_datalist, lock buffers needing > >write out and store them in an array. Buffers are also immediately refiled > >to > >BJ_Locked list or unfiled (if the write out is completed). When the array > >is > >full or we have to block on buffer lock, we submit all accumulated buffers > >for > >IO. > > > >Signed-off-by: Jan Kara > > > > > I have been running 4+ hours with this patch and seems to work fine. I > haven't hit any > assert yet :) > > I will let it run till tomorrow. I will let you know, how it goes. Great, thanks. BTW: Do you have any performance tests handy? The changes are big enough to cause some unexpected performance regressions, livelocks... If you don't have anything ready, I can setup and run something myself. Just that I don't like this testing too much ;). Honza -- Jan Kara SuSE CR Labs