From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 9 Oct 2008 15:55:38 +0200 From: Nick Piggin Subject: Re: [patch 5/8] mm: write_cache_pages integrity fix Message-ID: <20081009135538.GC9941@wotan.suse.de> References: <20081009155039.139856823@suse.de> <20081009174822.621353840@suse.de> <1223556765.14090.2.camel@think.oraclecorp.com> <20081009132711.GB9941@wotan.suse.de> <1223559358.14090.11.camel@think.oraclecorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1223559358.14090.11.camel@think.oraclecorp.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Chris Mason Cc: Andrew Morton , Mikulas Patocka , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org List-ID: On Thu, Oct 09, 2008 at 09:35:58AM -0400, Chris Mason wrote: > On Thu, 2008-10-09 at 15:27 +0200, Nick Piggin wrote: > > I don't think do_sync_mapping_range is broken as is. It simply splits > the operations into different parts. The caller can request that we > wait for pending IO first. It is. Not because of it's whacky API, but because it uses WB_SYNC_NONE. > WB_SYNC_NONE none just means don't wait for IO in flight, and there are > valid uses for it that will slow down if you switch them all to > WB_SYNC_ALL. To write_cache_pages it means that, but further down the chain (eg. block_write_full_page) it also means not to wait on other stuff. It has broadly meant "don't worry about data integirty" for a long time AFAIKS. > The problem is that we have a few flags and callers that mean almost but > not quite the same thing. Some people confuse WB_SYNC_NONE with > wbc->nonblocking. > > I'd leave WB_SYNC_NONE alone and set wbc->nr_to_write to the max int, or > just make a new flag that says write every dirty page in this range. Well it wouldn't hurt to clarify things. I'd rather introduce a new WB_SYNC_WRITEBACK or something for that guy. But anyway, as I said, it's just a minimal fix. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org