bcachefs: Fix more lockdep splats in debug.c

Similar to previous fixes, we can't incur page faults while holding
btree locks.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_iter.h

@@ -286,7 +286,7 @@ __always_inline
 static inline int btree_trans_restart_nounlock(struct btree_trans *trans, int err)
 {
 	BUG_ON(err <= 0);
-	BUG_ON(!bch2_err_matches(err, BCH_ERR_transaction_restart));
+	BUG_ON(!bch2_err_matches(-err, BCH_ERR_transaction_restart));
 
 	trans->restarted = err;
 	trans->last_restarted_ip = _THIS_IP_;

fs/bcachefs/debug.c

@@ -378,26 +378,25 @@ static ssize_t bch2_read_btree(struct file *file, char __user *buf,
 	i->size	= size;
 	i->ret	= 0;
 
-	bch2_trans_init(&trans, i->c, 0, 0);
+	ret = flush_buf(i);
+	if (ret)
+		return ret;
 
+	bch2_trans_init(&trans, i->c, 0, 0);
 	ret = for_each_btree_key2(&trans, iter, i->id, i->from,
 				  BTREE_ITER_PREFETCH|
 				  BTREE_ITER_ALL_SNAPSHOTS, k, ({
-		ret = flush_buf(i);
-		if (ret)
-			break;
-
 		bch2_bkey_val_to_text(&i->buf, i->c, k);
 		prt_newline(&i->buf);
-		0;
+		drop_locks_do(&trans, flush_buf(i));
 	}));
 	i->from = iter.pos;
 
+	bch2_trans_exit(&trans);
+
 	if (!ret)
 		ret = flush_buf(i);
 
-	bch2_trans_exit(&trans);
-
 	return ret ?: i->ret;
 }
 
@@ -429,19 +428,24 @@ static ssize_t bch2_read_btree_formats(struct file *file, char __user *buf,
 		return i->ret;
 
 	bch2_trans_init(&trans, i->c, 0, 0);
+retry:
+	bch2_trans_begin(&trans);
 
 	for_each_btree_node(&trans, iter, i->id, i->from, 0, b, ret) {
-		ret = flush_buf(i);
-		if (ret)
-			break;
-
 		bch2_btree_node_to_text(&i->buf, i->c, b);
 		i->from = !bpos_eq(SPOS_MAX, b->key.k.p)
 			? bpos_successor(b->key.k.p)
 			: b->key.k.p;
+
+		ret = drop_locks_do(&trans, flush_buf(i));
+		if (ret)
+			break;
 	}
 	bch2_trans_iter_exit(&trans, &iter);
 
+	if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
+		goto retry;
+
 	bch2_trans_exit(&trans);
 
 	if (!ret)
@@ -483,17 +487,13 @@ static ssize_t bch2_read_bfloat_failed(struct file *file, char __user *buf,
 		struct bkey_packed *_k =
 			bch2_btree_node_iter_peek(&l->iter, l->b);
 
-		ret = flush_buf(i);
-		if (ret)
-			break;
-
 		if (bpos_gt(l->b->key.k.p, i->prev_node)) {
 			bch2_btree_node_to_text(&i->buf, i->c, l->b);
 			i->prev_node = l->b->key.k.p;
 		}
 
 		bch2_bfloat_to_text(&i->buf, l->b, _k);
-		0;
+		drop_locks_do(&trans, flush_buf(i));
 	}));
 	i->from = iter.pos;
 

fs/bcachefs/errcode.h

@@ -224,7 +224,7 @@ bool __bch2_err_matches(int, int);
 
 static inline bool _bch2_err_matches(int err, int class)
 {
-	return err && __bch2_err_matches(err, class);
+	return err < 0 && __bch2_err_matches(err, class);
 }
 
 #define bch2_err_matches(_err, _class)			\

fs/bcachefs/io.c

@@ -1645,7 +1645,7 @@ static void bch2_nocow_write(struct bch_write_op *op)
 		percpu_ref_put(&bch_dev_bkey_exists(c, buckets[i].b.inode)->io_ref);
 
 	/* We can retry this: */
-	ret = BCH_ERR_transaction_restart;
+	ret = -BCH_ERR_transaction_restart;
 	goto out;
 }