Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752809AbaAJJcE (ORCPT ); Fri, 10 Jan 2014 04:32:04 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:39830 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751490AbaAJJcA (ORCPT ); Fri, 10 Jan 2014 04:32:00 -0500 Date: Fri, 10 Jan 2014 01:31:48 -0800 From: Christoph Hellwig To: Al Viro Cc: Linus Torvalds , Eric Paris , Steven Rostedt , Paul McKenney , Dave Chinner , linux-fsdevel , James Morris , Andrew Morton , Stephen Smalley , "Theodore Ts'o" , stable , Paul Moore , LKML , Matthew Wilcox , xfs@oss.sgi.com Subject: Re: [PATCH] vfs: Fix possible NULL pointer dereference in inode_permission() Message-ID: <20140110093148.GA26159@infradead.org> References: <20140109162731.12500986@gandalf.local.home> <20140109214239.GD29910@parisc-linux.org> <20140109165012.391db81e@gandalf.local.home> <20140109223127.GM10323@ZenIV.linux.org.uk> <20140109182523.5b50131f@gandalf.local.home> <20140109182756.17abaaa8@gandalf.local.home> <1389310626.15209.92.camel@localhost> <20140110000642.GN10323@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140110000642.GN10323@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 10, 2014 at 12:06:42AM +0000, Al Viro wrote: > Check what XFS is doing ;-/ That's where those call_rcu() have come from. > Sure, we can separate the simple "just do call_rcu(...->free_inode)" case > and hit it whenever full ->free_inode is there and ->destroy_inode isn't. > Not too pretty, but removal of tons of boilerplate might be worth doing > that anyway. But ->destroy_inode() is still needed for cases where fs > has its own idea of inode lifetime rules. Again, check what XFS is doing > in that area... Btw, I'd really love to get rid of the XFS ->destroy_inode abuse, it's been a long time thorn in the flesh. What's really needed there to make XFS behave more similar to everyone else is a way for the filesystem to say: "I can't actually free this inode right now, but I'll come back to you later". That's what we actually do right now, except we pretend that the VFS inode gets freed, while its memory lives on (punt intended). -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/