bcachefs: Kill bch2_btree_iter_set_pos_same_leaf()

The only reason we were keeping this around was for
BTREE_INSERT_NOUNLOCK semantics - if bch2_btree_iter_set_pos() advances
to the next leaf node, it'll drop the lock on the node that we just
inserted to.

But we don't rely on BTREE_INSERT_NOUNLOCK semantics for the extents
btree, just the inodes btree, and if we do need it for the extents btree
in the future we can do it more cleanly by cloning the iterator - this
lets us delete some special cases in the btree iterator code, which is
complicated enough as it is.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.c

@@ -516,12 +516,7 @@ static void bch2_btree_iter_verify_level(struct btree_iter *iter,
 	if (!bch2_btree_node_relock(iter, level))
 		return;
 
-	/*
-	 * Ideally this invariant would always be true, and hopefully in the
-	 * future it will be, but for now set_pos_same_leaf() breaks it:
-	 */
-	BUG_ON(iter->uptodate < BTREE_ITER_NEED_TRAVERSE &&
-	       !btree_iter_pos_in_node(iter, l->b));
+	BUG_ON(!btree_iter_pos_in_node(iter, l->b));
 
 	/*
 	 * node iterators don't use leaf node iterator:
@@ -1457,36 +1452,6 @@ struct btree *bch2_btree_iter_next_node(struct btree_iter *iter)
 
 /* Iterate across keys (in leaf nodes only) */
 
-void bch2_btree_iter_set_pos_same_leaf(struct btree_iter *iter, struct bpos new_pos)
-{
-	struct btree_iter_level *l = &iter->l[0];
-
-	EBUG_ON(iter->level != 0);
-	EBUG_ON(bkey_cmp(new_pos, iter->pos) < 0);
-	EBUG_ON(!btree_node_locked(iter, 0));
-	EBUG_ON(bkey_cmp(new_pos, l->b->key.k.p) > 0);
-
-	bkey_init(&iter->k);
-	iter->k.p = iter->pos = new_pos;
-	btree_iter_set_dirty(iter, BTREE_ITER_NEED_PEEK);
-
-	btree_iter_advance_to_pos(iter, l, -1);
-
-	/*
-	 * XXX:
-	 * keeping a node locked that's outside (even just outside) iter->pos
-	 * breaks __bch2_btree_node_lock(). This seems to only affect
-	 * bch2_btree_node_get_sibling so for now it's fixed there, but we
-	 * should try to get rid of this corner case.
-	 *
-	 * (this behaviour is currently needed for BTREE_INSERT_NOUNLOCK)
-	 */
-
-	if (bch2_btree_node_iter_end(&l->iter) &&
-	    btree_iter_pos_after_node(iter, l->b))
-		btree_iter_set_dirty(iter, BTREE_ITER_NEED_TRAVERSE);
-}
-
 static void btree_iter_pos_changed(struct btree_iter *iter, int cmp)
 {
 	unsigned l = iter->level;

fs/bcachefs/btree_iter.h

@@ -174,7 +174,6 @@ struct bkey_s_c bch2_btree_iter_next_slot(struct btree_iter *);
 
 struct bkey_s_c bch2_btree_iter_peek_cached(struct btree_iter *);
 
-void bch2_btree_iter_set_pos_same_leaf(struct btree_iter *, struct bpos);
 void __bch2_btree_iter_set_pos(struct btree_iter *, struct bpos, bool);
 void bch2_btree_iter_set_pos(struct btree_iter *, struct bpos);
 

fs/bcachefs/btree_update_leaf.c

@@ -951,12 +951,8 @@ int __bch2_trans_commit(struct btree_trans *trans)
 
 	trans_for_each_iter(trans, iter)
 		if ((trans->iters_live & (1ULL << iter->idx)) &&
-		    (iter->flags & BTREE_ITER_SET_POS_AFTER_COMMIT)) {
-			if (trans->flags & BTREE_INSERT_NOUNLOCK)
-				bch2_btree_iter_set_pos_same_leaf(iter, iter->pos_after_commit);
-			else
-				bch2_btree_iter_set_pos(iter, iter->pos_after_commit);
-		}
+		    (iter->flags & BTREE_ITER_SET_POS_AFTER_COMMIT))
+			bch2_btree_iter_set_pos(iter, iter->pos_after_commit);
 out:
 	bch2_journal_preres_put(&trans->c->journal, &trans->journal_preres);