On Fri, Sep 6, 2013 at 2:05 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> I can take that, but I'm really not convinced that we need writer lock
> there at all. After all, if we really can get livelocks on that one,
> we would be getting them on d_lookup()...
d_lookup() does a _single_ path component. That's a *big* difference.
Sure, the hash chain that d_lookup() (well, __d_lookup()) ends up
walking is a bit more complicated than just following the dentry
parent pointer, but that's much harder to trigger than just creating a
really deep directory structure of single-letter nested directories,
and then doing a "getcwd()" that walks 1024+ parents, while another
thread is looping renaming things..
So I personally do feel a lot safer with the fallback to write locking here.
Especially since it's pretty simple, so there isn't really much downside.
Linus
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