bcachefs: Fix restart handling in btree_node_scrub_work()

btree node scrub was sometimes failing to rewrite nodes with errors;
bch2_btree_node_rewrite() can return a transaction restart and we
weren't checking - the lockrestart_do() needs to wrap the entire
operation.

And there's a better helper it should've been using,
bch2_btree_node_rewrite_key(), which makes all this more convenient.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Author: Kent Overstreet

fs/bcachefs/btree_io.c

@@ -1986,28 +1986,12 @@ static void btree_node_scrub_work(struct work_struct *work)
 	prt_newline(&err);
 
 	if (!btree_node_scrub_check(c, scrub->buf, scrub->written, &err)) {
-		struct btree_trans *trans = bch2_trans_get(c);
-
-		struct btree_iter iter;
-		bch2_trans_node_iter_init(trans, &iter, scrub->btree,
-					  scrub->key.k->k.p, 0, scrub->level - 1, 0);
-
-		struct btree *b;
-		int ret = lockrestart_do(trans,
-			PTR_ERR_OR_ZERO(b = bch2_btree_iter_peek_node(trans, &iter)));
-		if (ret)
-			goto err;
-
-		if (bkey_i_to_btree_ptr_v2(&b->key)->v.seq == scrub->seq) {
-			bch_err(c, "error validating btree node during scrub on %s at btree %s",
-				scrub->ca->name, err.buf);
-
-			ret = bch2_btree_node_rewrite(trans, &iter, b, 0, 0);
-		}
-err:
-		bch2_trans_iter_exit(trans, &iter);
-		bch2_trans_begin(trans);
-		bch2_trans_put(trans);
+		int ret = bch2_trans_do(c,
+			bch2_btree_node_rewrite_key(trans, scrub->btree, scrub->level - 1,
+						    scrub->key.k, 0));
+		if (!bch2_err_matches(ret, ENOENT) &&
+		    !bch2_err_matches(ret, EROFS))
+			bch_err_fn_ratelimited(c, ret);
 	}
 
 	printbuf_exit(&err);

fs/bcachefs/btree_update_interior.c

@@ -2293,9 +2293,9 @@ int bch2_btree_node_rewrite(struct btree_trans *trans,
 	goto out;
 }
 
-static int bch2_btree_node_rewrite_key(struct btree_trans *trans,
-				       enum btree_id btree, unsigned level,
-				       struct bkey_i *k, unsigned flags)
+int bch2_btree_node_rewrite_key(struct btree_trans *trans,
+				enum btree_id btree, unsigned level,
+				struct bkey_i *k, unsigned flags)
 {
 	struct btree_iter iter;
 	bch2_trans_node_iter_init(trans, &iter,
@@ -2367,9 +2367,8 @@ static void async_btree_node_rewrite_work(struct work_struct *work)
 
 	int ret = bch2_trans_do(c, bch2_btree_node_rewrite_key(trans,
 						a->btree_id, a->level, a->key.k, 0));
-	if (ret != -ENOENT &&
-	    !bch2_err_matches(ret, EROFS) &&
-	    ret != -BCH_ERR_journal_shutdown)
+	if (!bch2_err_matches(ret, ENOENT) &&
+	    !bch2_err_matches(ret, EROFS))
 		bch_err_fn_ratelimited(c, ret);
 
 	spin_lock(&c->btree_node_rewrites_lock);

fs/bcachefs/btree_update_interior.h

@@ -176,6 +176,9 @@ static inline int bch2_foreground_maybe_merge(struct btree_trans *trans,
 
 int bch2_btree_node_rewrite(struct btree_trans *, struct btree_iter *,
 			    struct btree *, unsigned, unsigned);
+int bch2_btree_node_rewrite_key(struct btree_trans *,
+				enum btree_id, unsigned,
+				struct bkey_i *, unsigned);
 int bch2_btree_node_rewrite_pos(struct btree_trans *,
 				enum btree_id, unsigned,
 				struct bpos, unsigned, unsigned);