Return-Path: <linux-kernel-owner+willy=40w.ods.org@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id <S266155AbSKFVeD>; Wed, 6 Nov 2002 16:34:03 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org
	id <S266158AbSKFVeD>; Wed, 6 Nov 2002 16:34:03 -0500
Received: from thunk.org ([140.239.227.29]:43170 "EHLO thunker.thunk.org")
	by vger.kernel.org with ESMTP id <S266155AbSKFVd7>;
	Wed, 6 Nov 2002 16:33:59 -0500
Date: Wed, 6 Nov 2002 16:40:27 -0500
From: "Theodore Ts'o" <tytso@mit.edu>
To: chrisl@vmware.com
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
       Ext2 devel <ext2-devel@lists.sourceforge.net>,
       Linux Kernel List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Fix bug in ext3 htree rename: doesn't delete old name, leaves ino with bad nlink
Message-ID: <20021106214027.GA9711@think.thunk.org>
Mail-Followup-To: Theodore Ts'o <tytso@mit.edu>, chrisl@vmware.com,
	Jeremy Fitzhardinge <jeremy@goop.org>,
	Ext2 devel <ext2-devel@lists.sourceforge.net>,
	Linux Kernel List <linux-kernel@vger.kernel.org>
References: <1036471670.21855.15.camel@ixodes.goop.org> <20021105212415.GB1472@vmware.com> <20021106082500.GA3680@vmware.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20021106082500.GA3680@vmware.com>
User-Agent: Mutt/1.3.28i
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2559
Lines: 56

On Wed, Nov 06, 2002 at 12:25:00AM -0800, chrisl@vmware.com wrote:
> This should fix the ext3 htree rename problem. Please try it again.

I've looked over the patch, and I've got some comments....

>         handle = ext3_journal_start(old_dir, 2 * EXT3_DATA_TRANS_BLOCKS +
> -                                       EXT3_INDEX_EXTRA_TRANS_BLOCKS + 2);
> +                                       EXT3_INDEX_EXTRA_TRANS_BLOCKS + 3);

There's no need to increase the number of blocks that might need to be
dirtied; if ext3_delete_entry() can't find the missing entry, it won't
dirty the block, so the number of blocks that might need to modified
remains constant.

> -       ext3_delete_entry(handle, old_dir, old_de, old_bh);
> +       retval = ext3_delete_entry(handle, old_dir, old_de, old_bh);
> +       if (retval == -ENOENT) {
> +               /*
> +                * old_de can be moved during ext3_add_entry.
> +                */
> +               struct buffer_head * old_bh2;
> +               struct ext3_dir_entry_2 * old_de2;
> +               old_bh2 = ext3_find_entry (old_dentry, &old_de2);
> +               if (old_bh2) {
> +                       retval = ext3_delete_entry(handle, old_dir, old_de2,
> +                                                  old_bh2);
> +                       brelse(old_bh2);
> +               } else {
> +                       ext3_warning(old_dir->i_sb, "ext3_rename",
> +                                    "Deleting old file not found (%lu), %d",
> +                                    old_dir->i_ino, old_dir->i_nlink);
> +               }
>  
> +       }

Simply retrying the ext3_delete_entry() isn't sufficient, since
another ext3_add_entry() could move the directory entry again while
you're reading in the blocks as part of ext3_find_entry().  OK, that
would be pretty rare, since enough other directory adds would have
to fill up enough that another split could happen, but *is* possible.
(Surely our scheduler isn't that unfair....)

Probably a better thing to do is use a while loop, and retry as long
(a) ext3_delete_entry fails, and (b) old_dir->i_version has changed.
In practice this will probably never happen, but I'll feel better with
that change.

Anyway, I plan to make these two changes to your patch, and then
submit it to Linus.

						- Ted
-
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/