Re: [PATCH 01/10] Containers(V10): Basic container framework

Andrew Morton
2007-05-30T16:02:28Z

On Wed, 30 May 2007 07:02:00 -0700 "Paul Menage" <menage@google.com> wrote:

>
> >
> > People have hit unpleasant problems before now running iput() against
> > partially-constructed inodes.
>
> What kinds of problems? Are there bits of state that I should fully
> construct even if I'm going to iput() it, or is there a better
> function to call? fs/ext3/super.c seems to do the same thing.

I don't recall, actually. But it crashed.

I guess the fault-injection code could be used to trigger errors here.

> > >
> > > +static inline void get_first_subsys(const struct container *cont,
> > > + struct container_subsys_state **css,
> > > + int *subsys_id) {
> > > + const struct containerfs_root *root = cont->root;
> > > + const struct container_subsys *test_ss;
> > > + BUG_ON(list_empty(&root->subsys_list));
> > > + test_ss = list_entry(root->subsys_list.next,
> > > + struct container_subsys, sibling);
> > > + if (css) {
> > > + *css = cont->subsys[test_ss->subsys_id];
> > > + BUG_ON(!*css);
> > > + }
> > > + if (subsys_id)
> > > + *subsys_id = test_ss->subsys_id;
> > > +}
> >
> > This ends up having several callers and its too large to inline.
>
> Two large from a compiler PoV or from a style PoV? It's basically just
> six dereferences and two comparisons, plus the BUG_ON()s.

It will end up generating more .text this way. We figure that this makes
it slower, due to increased icache footprint.