Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757071AbZDRO0E (ORCPT ); Sat, 18 Apr 2009 10:26:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756075AbZDROZv (ORCPT ); Sat, 18 Apr 2009 10:25:51 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:34824 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755497AbZDROZu (ORCPT ); Sat, 18 Apr 2009 10:25:50 -0400 Date: Sat, 18 Apr 2009 15:25:40 +0100 From: Al Viro To: hooanon05@yahoo.co.jp Cc: David Woodhouse , bfields@citi.umich.edu, hch@infradead.org, "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" Subject: Re: [PATCH] Fix i_mutex handling in nfsd readdir. Message-ID: <20090418142540.GR26366@ZenIV.linux.org.uk> References: <8036.1237474444@jrobl> <1237475837.16359.106.camel@macbook.infradead.org> <8913.1237476890@jrobl> <1239960739.3428.33.camel@macbook.infradead.org> <20090417193233.GM26366@ZenIV.linux.org.uk> <1240006620.19059.41.camel@macbook.infradead.org> <20090417224350.GN26366@ZenIV.linux.org.uk> <20090417225306.GO26366@ZenIV.linux.org.uk> <1240013753.21423.86.camel@macbook.infradead.org> <905.1240024314@jrobl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <905.1240024314@jrobl> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1200 Lines: 29 On Sat, Apr 18, 2009 at 12:11:54PM +0900, hooanon05@yahoo.co.jp wrote: > > David Woodhouse: > > This patch fixes it by locking the directory's i_mutex again before > > calling the filldir functions. The original deadlocks which commit > > 14f7dd63 was designed to avoid are still avoided, because they were due > > to fs-internal locking, not i_mutex. > ::: > > --- a/fs/namei.c > > +++ b/fs/namei.c > > @@ -1248,6 +1248,8 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) > > int err; > > struct qstr this; > > > > + WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); > > + > > err = __lookup_one_len(name, &this, base, len); > > I'd suggest this checking is done only when CONFIG_DEBUG_KERNEL (or > something) is enabled. Because unconditional checking costs high for the > well-reviewed lookup code. Frankly, I'd rather have DEBUG_WARN... conditional on that, rather than cluttering code with ifdefs... -- 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/