From: Joel Becker Subject: Re: [PATCH 1/3] jbd2 : Make jbd2 transaction handle allocation to return errors and handle them gracefully. Date: Sat, 22 Jan 2011 22:29:01 -0800 Message-ID: <20110123062900.GA7436@noexit> References: <20110123054049.GC3237@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Manish Katiyar , Jan Kara , ext4 To: Ted Ts'o Return-path: Received: from zeniv.linux.org.uk ([195.92.253.2]:42648 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750953Ab1AWG3J (ORCPT ); Sun, 23 Jan 2011 01:29:09 -0500 Content-Disposition: inline In-Reply-To: <20110123054049.GC3237@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, Jan 23, 2011 at 12:40:49AM -0500, Ted Ts'o wrote: > On Sat, Jan 22, 2011 at 07:32:44PM -0800, Manish Katiyar wrote: > > Hi Jan, > > > > This is the follow up from https://lkml.org/lkml/2011/1/17/154 > > Following patches make jbd2 to use GFP_KERNEL for transaction > > allocation if the caller can handle the errors. Following is the list > > of functions that I updated to pass the new flag. Also below is the > > list of functions which still have the old behavior and pass the old > > flags (either because they can't deal with errors, or I wasn't too > > sure so I did conservatively). Appreciate your feedback. The other > > callers of jbd2_journal_start() are from ocfs2, they still pass the > > old flag. > > Hmm, I wonder if it would be better to use > > jbd2_journal_start(...) > > and > > jbd2_journal_start_nofail(...) This API is markedly better to read. Btw, does _nofail() mean no possible failures, or just no memory errors? If it is no failures, I'd love to see the function become void. > The tradeoff is that long-term, the code is more readable (as opposed > to having people look up what a random "true" or "false" value means). > But short-term, while it will make the patch smaller, it also makes > the patch harder audit, since we need to look at all of the places > where we _haven't_ made a change to make sure those call sites can > tolerate an error return. I think we should start with jbd2_journal_start_can_fail() or something like it, and change it back to jbd2_journal_start() in the next window. It's a silly name, but it catches exactly what you are worried about. Joel -- Life's Little Instruction Book #94 "Make it a habit to do nice things for people who will never find out." http://www.jlbec.org/ jlbec@evilplan.org