Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759434Ab0FPTQV (ORCPT ); Wed, 16 Jun 2010 15:16:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30692 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756493Ab0FPTQT (ORCPT ); Wed, 16 Jun 2010 15:16:19 -0400 Date: Wed, 16 Jun 2010 15:15:56 -0400 From: Jeff Layton To: Valerie Aurora Cc: Alexander Viro , Christoph Hellwig , Miklos Szeredi , Jan Blunck , Jamie Lokier , David Woodhouse , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] d_ino considered harmful Message-ID: <20100616151556.23cc9113@tlielax.poochiereds.net> In-Reply-To: <20100616185913.GA15566@shell> References: <20100616185913.GA15566@shell> Mime-Version: 1.0 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: 2029 Lines: 54 On Wed, 16 Jun 2010 14:59:13 -0400 Valerie Aurora wrote: > Who needs d_ino anyway? I am running a kernel with this patch - > Gnome, a browser, IRC, kernel compile, etc. and everything works. > > -VAL > > commit 184f3919d0071f3bfa40010aa6919ea89999d79b > Author: Valerie Aurora > Date: Wed Jun 16 11:05:06 2010 -0700 > > VFS: Always return 0 for d_ino > > Use of d_ino without the corresponding st_dev is always buggy in the > presence of submounts, bind mounts, and union mounts. E.g., the d_ino > of a mountpoint will be the inode number of the directory under the > mountpoint, not the mounted directory. Correct code must call stat(), > which returns the correct device ID and inode in st_dev and st_ino. > Since no one should be using d_ino anyway, always return 0 to detect > bugs. > > diff --git a/fs/readdir.c b/fs/readdir.c > index dd3eae1..38ea772 100644 > --- a/fs/readdir.c > +++ b/fs/readdir.c > @@ -91,7 +91,9 @@ static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset > > if (buf->result) > return -EINVAL; > - d_ino = ino; > + /* Use of d_ino without st_dev is always buggy. */ > + d_ino = 0; > + > if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) { > buf->result = -EOVERFLOW; > return -EOVERFLOW; > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > That may run afoul of the following check (where d_ino is compared to ino). You can probably just remove that check though since you can be reasonably sure that 0 will never overflow the field. -- Jeff Layton -- 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/