From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id CF5138D0017 for ; Mon, 15 Nov 2010 14:16:09 -0500 (EST) Date: Mon, 15 Nov 2010 20:16:02 +0100 From: Andrea Arcangeli Subject: Re: Oops while rebalancing, now unmountable. Message-ID: <20101115191602.GK6809@random.random> References: <1289236257.3611.3.camel@mars> <1289310046-sup-839@think> <1289326892.4231.2.camel@mars> <1289764507.4303.9.camel@mars> <20101114204206.GV6809@random.random> <20101114220018.GA4512@infradead.org> <20101114221222.GX6809@random.random> <20101115182314.GA2493@infradead.org> <20101115184657.GJ6809@random.random> <1289847339-sup-4591@think> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1289847339-sup-4591@think> Sender: owner-linux-mm@kvack.org To: Chris Mason Cc: Christoph Hellwig , Shane Shrybman , linux-btrfs , linux-mm , linux-fsdevel List-ID: On Mon, Nov 15, 2010 at 02:03:55PM -0500, Chris Mason wrote: > It always returns either -EIO or -EAGAIN, so the caller will try again > and then end up waiting on PageWriteback? Returning any error from ->writepage will make writeout return -EIO so aborting the migration for that page. If no error is returned from ->writepage, writeout will return -EAGAIN the caller will try again after wait_on_page_writeback. I think I misread the code when in prev mail I worried about not waiting on PG_writeback after writeout()... :) So the ideal would be not to return errors when ->writepage submitted the writeback I/O successfully but if it returns -EIO/-EAGAIN there's no risk whatsoever (except compaction will be less effective). -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org