Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754313AbZFBVtq (ORCPT ); Tue, 2 Jun 2009 17:49:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753736AbZFBVtg (ORCPT ); Tue, 2 Jun 2009 17:49:36 -0400 Received: from mx2.redhat.com ([66.187.237.31]:38784 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753626AbZFBVtf (ORCPT ); Tue, 2 Jun 2009 17:49:35 -0400 Message-ID: <4A259E49.4020003@sandeen.net> Date: Tue, 02 Jun 2009 16:48:57 -0500 From: Eric Sandeen User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Jan Kara CC: Wu Fengguang , Andrew Morton , LKML , Masayoshi MIZUMA , "linux-fsdevel@vger.kernel.org" , "viro@zeniv.linux.org.uk" , Nick Piggin Subject: Re: [PATCH] skip I_CLEAR state inodes References: <20090318170237.8F6C.61FB500B@jp.fujitsu.com> <20090323103846.GA16577@localhost> <20090324155655.2684.61FB500B@jp.fujitsu.com> <20090324074457.GA7745@localhost> <20090324120502.GC23439@duck.suse.cz> <20090324124001.GA25326@localhost> <4A244A5B.7070605@sandeen.net> <20090602085523.GC7161@localhost> <20090602113736.GB15010@duck.suse.cz> In-Reply-To: <20090602113736.GB15010@duck.suse.cz> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2305 Lines: 57 Jan Kara wrote: > On Tue 02-06-09 16:55:23, Wu Fengguang wrote: >> On Tue, Jun 02, 2009 at 05:38:35AM +0800, Eric Sandeen wrote: >>> Wu Fengguang wrote: >>>> Add I_CLEAR tests to drop_pagecache_sb(), generic_sync_sb_inodes() and >>>> add_dquot_ref(). >>>> >>>> clear_inode() will switch inode state from I_FREEING to I_CLEAR, >>>> and do so _outside_ of inode_lock. So any I_FREEING testing is >>>> incomplete without the testing of I_CLEAR. >>>> >>>> Masayoshi MIZUMA first discovered the bug in drop_pagecache_sb() and >>>> Jan Kara reminds fixing the other two cases. Thanks! >>> Is there a reason it's not done for __sync_single_inode as well? >> It missed the glance because it don't have an obvious '|' in the line ;) >> >>> Jeff Layton asked the question and I'm following it up :) >>> >>> __sync_single_inode currently only tests I_FREEING, but I think we are >>> safe because __sync_single_inode sets I_SYNC, and clear_inode waits for >>> I_SYNC to be cleared before it changes I_STATE. >> But I_SYNC is removed just before the I_FREEING test, so we still have >> a small race window? yep that's right. inode->i_state &= ~I_SYNC; >>> clear_inode->inode_sync_wait here and find it clear <<< if (!(inode->i_state & I_FREEING)) { ... >> --- linux.orig/fs/fs-writeback.c >> +++ linux/fs/fs-writeback.c >> @@ -316,7 +316,7 @@ __sync_single_inode(struct inode *inode, >> spin_lock(&inode_lock); >> WARN_ON(inode->i_state & I_NEW); >> inode->i_state &= ~I_SYNC; >> - if (!(inode->i_state & I_FREEING)) { >> + if (!(inode->i_state & (I_FREEING | I_CLEAR))) { >> if (!(inode->i_state & I_DIRTY) && >> mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { > Is the whole if needed? I had an impression that everyone calling > __sync_single_inode() should better take care it does not race with inode > freeing... So WARN_ON would be more appropriate IMHO. Maybe both then (both a WARN on and then the test (defensive here, I guess)) because if we continue we may wander into a poisoned list pointer and explode, right? -Eric -- 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/