bcachefs: Fix set_should_be_locked() call in peek_slot()

set_should_be_locked() needs to be called before peek_key_cache(), which
traverses other paths and may do a trans unlock/relock.

This fixes an assertion pop in path_peek_slot(), when the path we're
using is unexpectedly not uptodate.

Signed-off-by: Kent Overstreet <[email protected]>

Author: Kent Overstreet

fs/bcachefs/btree_iter.c

@@ -2749,7 +2749,7 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_trans *trans, struct btre
 	ret = trans_maybe_inject_restart(trans, _RET_IP_);
 	if (unlikely(ret)) {
 		k = bkey_s_c_err(ret);
-		goto out_no_locked;
+		goto out;
 	}
 
 	/* extents can't span inode numbers: */
@@ -2769,13 +2769,15 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_trans *trans, struct btre
 	ret = bch2_btree_path_traverse(trans, iter->path, iter->flags);
 	if (unlikely(ret)) {
 		k = bkey_s_c_err(ret);
-		goto out_no_locked;
+		goto out;
 	}
 
 	struct btree_path *path = btree_iter_path(trans, iter);
 	if (unlikely(!btree_path_node(path, path->level)))
 		return bkey_s_c_null;
 
+	btree_path_set_should_be_locked(trans, path);
+
 	if ((iter->flags & BTREE_ITER_cached) ||
 	    !(iter->flags & (BTREE_ITER_is_extents|BTREE_ITER_filter_snapshots))) {
 		k = bkey_s_c_null;
@@ -2796,12 +2798,12 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_trans *trans, struct btre
 			if (!bkey_err(k))
 				iter->k = *k.k;
 			/* We're not returning a key from iter->path: */
-			goto out_no_locked;
+			goto out;
 		}
 
-		k = bch2_btree_path_peek_slot(trans->paths + iter->path, &iter->k);
+		k = bch2_btree_path_peek_slot(btree_iter_path(trans, iter), &iter->k);
 		if (unlikely(!k.k))
-			goto out_no_locked;
+			goto out;
 
 		if (unlikely(k.k->type == KEY_TYPE_whiteout &&
 			     (iter->flags & BTREE_ITER_filter_snapshots) &&
@@ -2839,7 +2841,7 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_trans *trans, struct btre
 		}
 
 		if (unlikely(bkey_err(k)))
-			goto out_no_locked;
+			goto out;
 
 		next = k.k ? bkey_start_pos(k.k) : POS_MAX;
 
@@ -2861,8 +2863,6 @@ struct bkey_s_c bch2_btree_iter_peek_slot(struct btree_trans *trans, struct btre
 		}
 	}
 out:
-	btree_path_set_should_be_locked(trans, btree_iter_path(trans, iter));
-out_no_locked:
 	bch2_btree_iter_verify_entry_exit(iter);
 	bch2_btree_iter_verify(trans, iter);
 	ret = bch2_btree_iter_verify_ret(trans, iter, k);