Hi Sascha!
On Mon 11-11-19 09:57:45, Sascha Hauer wrote:
> On Wed, Nov 06, 2019 at 11:14:28AM +0100, Jan Kara wrote:
> > > +/**
> > > + * ubifs_dqblk_find_next - find the next qid
> > > + * @c: UBIFS file-system description object
> > > + * @qid: The qid to look for
> > > + *
> > > + * Find the next dqblk entry with a qid that is bigger or equally big than the
> > > + * given qid. Returns the next dqblk entry if found or NULL if no dqblk exists
> > > + * with a qid that is at least equally big.
> > > + */
> > > +static struct ubifs_dqblk *ubifs_dqblk_find_next(struct ubifs_info *c,
> > > + struct kqid qid)
> > > +{
> > > + struct rb_node *node = c->dqblk_tree[qid.type].rb_node;
> > > + struct ubifs_dqblk *next = NULL;
> > > +
> > > + while (node) {
> > > + struct ubifs_dqblk *ud = rb_entry(node, struct ubifs_dqblk, rb);
> > > +
> > > + if (qid_eq(qid, ud->kqid))
> > > + return ud;
> > > +
> > > + if (qid_lt(qid, ud->kqid)) {
> > > + if (!next || qid_lt(ud->kqid, next->kqid))
^^^
This condition looks superfluous as it should be always true. The last node
where you went left should be the least greater node if you didn't find the
exact match...
> > > + next = ud;
> > > +
> > > + node = node->rb_left;
> > > + } else {
> > > + node = node->rb_right;
> > > + }
> > > + }
> > > +
> > > + return next;
> > > +}
> >
> > Why not use rb_next() here? It should do what you need, shouldn't it?
>
> I could use rb_next(), but it defeats the purpose of a tree to iterate
> over the whole tree to find an entry. If I wanted that I would have used
> a list.
I wasn't quite clear in my suggestion and now that I look at it it was
actually misleading. I'm sorry for that. So a second try :):
You have ubifs_dqblk_find() and ubifs_dqblk_find_next() doing very similar
rbtree traversal. I think you could remove that duplication by using
ubifs_dqblk_find_next() from ubifs_dqblk_find()?
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
