linux-kernel - Re: [PATCH] [RFC] remove ext3 inode from orphan list when link and unlink race

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Date:	Fri, 12 Jan 2007 15:14:36 -0600
From:	Eric Sandeen <sandeen@...hat.com>
To:	Alex Tomas <alex@...sterfs.com>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] [RFC] remove ext3 inode from orphan list when link and
 unlink race

Alex Tomas wrote:
> interesting ..
> 
> I thought VFS doesn't allow concurrent operations.
> if unlink goes first, then link should wait on the
> parent's i_mutex and then found no source name.
> 
> thanks, Alex

Well... I was wondering that myself, whether this race should even
happen.  But the bottom of do_unlinkat looks like:

        mutex_unlock(&nd.dentry->d_inode->i_mutex);
        if (inode)
                iput(inode);    /* truncate the inode here */
exit1:
        path_release(&nd);
exit:
        putname(name);
        return error;

so I think it's possible that link can sneak in there & find it after
the mutex is dropped...?  Is this ok? :)  It's certainly -happening-
anyway....

-Eric
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