On Mon, May 23, 2011 at 12:13:07PM -0400, Josef Bacik wrote:
> On 05/21/2011 10:11 PM, Al Viro wrote:
> > On Fri, May 20, 2011 at 01:44:30PM -0400, Josef Bacik wrote:
> >> + if (unlikely(d_need_lookup(dentry))) {
> >> + if (nameidata_dentry_drop_rcu(nd, dentry))
> >> + return -ECHILD;
> >> + dput(dentry);
> >> + dentry = NULL;
> >> + goto retry;
> >
> > Yecchhh... How about simple goto unlazy; here instead and doing the rest
> > there? Especially since you have the same kind of thing elsewhere in the
> > same sucker. It had been bloody painful to untangle that thing; let's not
> > add to the rat's nest that still remains...
>
> This is where I was a little confused, which is why I added this code. It
> seems that having goto unlazy; will mean that we will come down to this
> section
>
> if (unlikely(status <= 0 )) {
> if (status < 0) {
> dput(dentry);
> return status;
> }
> if (!d_invalidate(dentry)) {
> dput(dentry);
> dentry = NULL;
> need_reval = 1;
> goto retry;
> }
> }
>
> and d_invalidate will unhash us so we won't find our new dentry in the cache
> which makes this whole exercise useless. Is there a different way you'd
> like
> this cleaned up? Thanks,
Not *into* the loop; just before the beginning of that loop. IOW, put
if (dentry && unlikely(dentry->d_flags & DCACHE_NEED_LOOKUP)) {
dput(dentry);
dentry = NULL;
}
just before retry: instead of doing it in non-lazy branch. Voila - your
code in the lazy branch becomes
if (unlikely(dentry->d_flags & DCACHE_NEED_LOOKUP))
goto unlazy;
and that's it. Can you resend it with such modifications?
ObMemoryPressureIssues: I really hoped to get Dave's patch (per-sb shrinkers)
in that cycle, but it'll probably have to wait for the next one...
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