bcachefs: BCH_WRITE_ALLOC_NOWAIT no longer applies to open bucket allocation

rebalance writes must be BCH_WRITE_ALLOC_NOWAIT because they don't
allocate from the full filesystem - but we don't want spurious
allocation failures due to open buckets.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/alloc_foreground.c

@@ -600,6 +600,7 @@ static struct open_bucket *bch2_bucket_alloc_trans(struct btree_trans *trans,
 				      enum bch_watermark watermark,
 				      enum bch_data_type data_type,
 				      struct closure *cl,
+				      bool nowait,
 				      struct bch_dev_usage *usage)
 {
 	struct bch_fs *c = trans->c;
@@ -609,7 +610,7 @@ static struct open_bucket *bch2_bucket_alloc_trans(struct btree_trans *trans,
 	struct bucket_alloc_state s = {
 		.btree_bitmap = data_type == BCH_DATA_btree,
 	};
-	bool waiting = false;
+	bool waiting = nowait;
 again:
 	bch2_dev_usage_read_fast(ca, usage);
 	avail = dev_buckets_free(ca, *usage, watermark);
@@ -685,7 +686,7 @@ struct open_bucket *bch2_bucket_alloc(struct bch_fs *c, struct bch_dev *ca,
 
 	bch2_trans_do(c, NULL, NULL, 0,
 		      PTR_ERR_OR_ZERO(ob = bch2_bucket_alloc_trans(trans, ca, watermark,
-							data_type, cl, &usage)));
+							data_type, cl, false, &usage)));
 	return ob;
 }
 
@@ -800,7 +801,8 @@ int bch2_bucket_alloc_set_trans(struct btree_trans *trans,
 			continue;
 		}
 
-		ob = bch2_bucket_alloc_trans(trans, ca, watermark, data_type, cl, &usage);
+		ob = bch2_bucket_alloc_trans(trans, ca, watermark, data_type,
+					     cl, flags & BCH_WRITE_ALLOC_NOWAIT, &usage);
 		if (!IS_ERR(ob))
 			bch2_dev_stripe_increment_inlined(ca, stripe, &usage);
 		bch2_dev_put(ca);
@@ -1493,11 +1495,12 @@ int bch2_alloc_sectors_start_trans(struct btree_trans *trans,
 	    try_decrease_writepoints(trans, write_points_nr))
 		goto retry;
 
-	if (bch2_err_matches(ret, BCH_ERR_open_buckets_empty) ||
+	if (cl && bch2_err_matches(ret, BCH_ERR_open_buckets_empty))
+		ret = -BCH_ERR_bucket_alloc_blocked;
+
+	if (cl && !(flags & BCH_WRITE_ALLOC_NOWAIT) &&
 	    bch2_err_matches(ret, BCH_ERR_freelist_empty))
-		return cl
-			? -BCH_ERR_bucket_alloc_blocked
-			: -BCH_ERR_ENOSPC_bucket_alloc;
+		ret = -BCH_ERR_bucket_alloc_blocked;
 
 	return ret;
 }

fs/bcachefs/errcode.h

@@ -119,8 +119,8 @@
 	x(EEXIST,			EEXIST_str_hash_set)			\
 	x(EEXIST,			EEXIST_discard_in_flight_add)		\
 	x(EEXIST,			EEXIST_subvolume_create)		\
-	x(0,				open_buckets_empty)			\
-	x(0,				freelist_empty)				\
+	x(ENOSPC,			open_buckets_empty)			\
+	x(ENOSPC,			freelist_empty)				\
 	x(BCH_ERR_freelist_empty,	no_buckets_found)			\
 	x(0,				transaction_restart)			\
 	x(BCH_ERR_transaction_restart,	transaction_restart_fault_inject)	\

fs/bcachefs/io_write.c

@@ -1447,9 +1447,7 @@ static void __bch2_write(struct bch_write_op *op)
 				op->nr_replicas_required,
 				op->watermark,
 				op->flags,
-				(op->flags & (BCH_WRITE_ALLOC_NOWAIT|
-					      BCH_WRITE_ONLY_SPECIFIED_DEVS))
-				? NULL : &op->cl, &wp));
+				&op->cl, &wp));
 		if (unlikely(ret)) {
 			if (bch2_err_matches(ret, BCH_ERR_operation_blocked))
 				break;
@@ -1592,6 +1590,9 @@ CLOSURE_CALLBACK(bch2_write)
 	BUG_ON(!op->write_point.v);
 	BUG_ON(bkey_eq(op->pos, POS_MAX));
 
+	if (op->flags & BCH_WRITE_ONLY_SPECIFIED_DEVS)
+		op->flags |= BCH_WRITE_ALLOC_NOWAIT;
+
 	op->nr_replicas_required = min_t(unsigned, op->nr_replicas_required, op->nr_replicas);
 	op->start_time = local_clock();
 	bch2_keylist_init(&op->insert_keys, op->inline_keys);