On Wed, Mar 02, 2016 at 11:00:01AM +0800, Yan, Zheng wrote:
> > This code dates back to when Ceph was originally upstreamed, so the
> > history is murky, but I expect at that point I wanted to avoid hashing in
> > the no-lease case. But I don't think it matters. We should just remove
> > the prehash argument from splice_dentry entirely.
> >
> > Zheng, does that sound right?
>
> Yes. I think we can remove the d_rehash(dn) call and rehash parameter.
Another question in the same general area:
/* null dentry? */
if (!rinfo->head->is_target) {
dout("fill_trace null dentry\n");
if (d_really_is_positive(dn)) {
ceph_dir_clear_ordered(dir);
dout("d_delete %p\n", dn);
d_delete(dn);
} else {
dout("d_instantiate %p NULL\n", dn);
d_instantiate(dn, NULL);
if (have_lease && d_unhashed(dn))
d_rehash(dn);
update_dentry_lease(dn, rinfo->dlease,
session,
req->r_request_started);
}
goto done;
}
What's that d_instantiate() about? We have just checked that it's
negative; what's the point of setting ->d_inode to NULL again? Would it
be OK if we just do
} else {
if (have_lease && d_unhashed(dn))
d_add(dn, NULL);
update_dentry_lease(dn, rinfo->dlease,
session,
req->r_request_started);
}
in there? As an aside, tracking back to the originating fs method is
painful as hell ;-/ I _think_ that rehash can be hit during ->lookup()
returning a negative, but I wouldn't bet a dime on it not happening from
other methods... AFAICS, the change should be OK regardless of what
it's been called from, but... _ouch_. Is is documented anywhere public?
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