From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH] Fix ext2 error reporting on fsync Date: Thu, 12 Jan 2006 18:16:28 -0800 Message-ID: <20060112181628.63c4bf39.akpm@osdl.org> References: <20060111174302.GD16728@atrey.karlin.mff.cuni.cz> <20060112142656.GB14235@atrey.karlin.mff.cuni.cz> <20060112124717.6e242802.akpm@osdl.org> <200601122108.55103.mason@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: jack@suse.cz, linux-fsdevel@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.4]:10471 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932668AbWAMCQw (ORCPT ); Thu, 12 Jan 2006 21:16:52 -0500 To: Chris Mason In-Reply-To: <200601122108.55103.mason@suse.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Chris Mason wrote: > > On Thursday 12 January 2006 15:47, Andrew Morton wrote: > > Jan Kara wrote: > > > > Jan Kara wrote: > > > > > > > > hm, yes, try_to_free_buffers() against a blockdev page is a problem. > > > > But I think it's fixable. > > > > > > > > In the second loop of drop_buffers(), if we find a bh which had a write > > > > error we need to set AS_EIO on the address_space which is interested in > > > > this buffer. > > > > > > > > That address_space is pinned by a) the fact that it has buffers at > > > > ->private_list and b) we hold the blockdev mapping's private_lock. > > > > > > > > The only problem is actually _finding_ the address_space which is > > > > interested in this buffer_head. Looks like we'd need a backpointer in > > > > the buffer_head. > > > > > > Yes, the pointer seems to be inevitable in this solution. If you think > > > the improvement is worth adding 4 bytes to each buffer_head, then I can > > > write the patch. > > > > hm. It only affects what are now rarely-used filesystems like ext2, minix, > > etc. Not sure about reiser3. But it is a strict correctness issue. I > > suppose we should do it. It'd be nice to find a way to avoid increasing > > the bh size.. > > > > I know my patch is pretty nasty, but is it really worth adding complexity to > the base code for this corner case? > It's not much complexity: a few set_bits and test_and_clear_bits in three places. The main drawback is a larger buffer_head. Yeah, it's a pita, but it is a data-integrity correctness thing. > > It'll be a hard patch to test. > > I'll dig up $partner. They had a nasty test suite for that kind of thing. > That'd be neat. They do IO error simulations?