Re: processes hung after sys_renameat, and 'missing' processes

From: Linus Torvalds
Date: Wed Jun 06 2012 - 21:45:55 EST


On Wed, Jun 6, 2012 at 6:31 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> And you want to check i_mutex on old parent, not the file being moved
> itself.  IOW, the second one should be
>
> if (dentry->d_parent != dentry)
>        WARN_ON_ONCE(!mutex_is_locked(&dentry->d_parent->d_inode->i_mutex));

Do you even need the "dentry->d_parent != dentry" test? When do we
even rename root dentries?

I do notice that we have that IS_ROOT() test in __d_move(), but now
that I look at it I wonder *why* we have it..

Anyway, Dave, you should probably trust Al over me here - that test
obviously won't hurt, even if I can't see immediately when it would
trigger either.

Linus
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