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Message-ID: <20110728003421.GA3133@thunk.org>
Date: Wed, 27 Jul 2011 20:34:22 -0400
From: Ted Ts'o <tytso@....edu>
To: Al Viro <viro@...IV.linux.org.uk>
Cc: Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: fix races in ext4_sync_parent()
On Wed, Jul 27, 2011 at 02:15:54AM +0100, Al Viro wrote:
> On Tue, Jul 26, 2011 at 09:13:12PM -0400, Theodore Ts'o wrote:
> > + inode = igrab(inode);
> > + while (ext4_test_inode_state(inode, EXT4_STATE_NEWENTRY)) {
> > ext4_clear_inode_state(inode, EXT4_STATE_NEWENTRY);
> > - dentry = list_entry(inode->i_dentry.next,
> > - struct dentry, d_alias);
> > - if (!dentry || !dentry->d_parent || !dentry->d_parent->d_inode)
> > + dentry = list_first_entry(&inode->i_dentry,
> > + struct dentry, d_alias);
>
> ... and what if you don't have a dentry for that inode anymore?
I thought you were complaining that dentry could never be NULL
earlier? We earlier checked for NULL, but I figured you knew
something I didn't....
> > + next = igrab(dentry->d_parent->d_inode);
>
> what protects you against rename() (OK, d_mode()) here?
Does it matter? We'll get either the old or the new parent directory,
but either way it will be a valid inode, right? Or am I missing
something?
- Ted
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