bcachefs: Fix refcount leak in check_fix_ptrs()

fsck_err() does a goto fsck_err on error; factor out check_fix_ptr() so
that our error label can drop our device ref.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/buckets.c

@@ -465,21 +465,16 @@ int bch2_update_cached_sectors_list(struct btree_trans *trans, unsigned dev, s64
 	return bch2_update_replicas_list(trans, &r.e, sectors);
 }
 
-int bch2_check_fix_ptrs(struct btree_trans *trans,
-			enum btree_id btree, unsigned level, struct bkey_s_c k,
-			enum btree_iter_update_trigger_flags flags)
+static int bch2_check_fix_ptr(struct btree_trans *trans,
+			      struct bkey_s_c k,
+			      struct extent_ptr_decoded p,
+			      const union bch_extent_entry *entry,
+			      bool *do_update)
 {
 	struct bch_fs *c = trans->c;
-	struct bkey_ptrs_c ptrs_c = bch2_bkey_ptrs_c(k);
-	const union bch_extent_entry *entry_c;
-	struct extent_ptr_decoded p = { 0 };
-	bool do_update = false;
 	struct printbuf buf = PRINTBUF;
 	int ret = 0;
 
-	percpu_down_read(&c->mark_lock);
-
-	bkey_for_each_ptr_decode(k.k, ptrs_c, p, entry_c) {
 	struct bch_dev *ca = bch2_dev_tryget(c, p.ptr.dev);
 	if (!ca) {
 		if (fsck_err(c, ptr_to_invalid_device,
@@ -488,12 +483,12 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			     p.ptr.dev,
 			     (printbuf_reset(&buf),
 			      bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
-				do_update = true;
-			continue;
+			*do_update = true;
+		return 0;
 	}
 
 	struct bucket *g = PTR_GC_BUCKET(ca, &p.ptr);
-		enum bch_data_type data_type = bch2_bkey_ptr_data_type(k, p, entry_c);
+	enum bch_data_type data_type = bch2_bkey_ptr_data_type(k, p, entry);
 
 	if (fsck_err_on(!g->gen_valid,
 			c, ptr_to_missing_alloc_key,
@@ -508,7 +503,7 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			g->gen_valid		= true;
 			g->gen			= p.ptr.gen;
 		} else {
-				do_update = true;
+			*do_update = true;
 		}
 	}
 
@@ -530,7 +525,7 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			g->dirty_sectors	= 0;
 			g->cached_sectors	= 0;
 		} else {
-				do_update = true;
+			*do_update = true;
 		}
 	}
 
@@ -543,7 +538,7 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			p.ptr.gen,
 			(printbuf_reset(&buf),
 			 bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
-			do_update = true;
+		*do_update = true;
 
 	if (fsck_err_on(!p.ptr.cached && gen_cmp(p.ptr.gen, g->gen) < 0,
 			c, stale_dirty_ptr,
@@ -554,10 +549,10 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			p.ptr.gen, g->gen,
 			(printbuf_reset(&buf),
 			 bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
-			do_update = true;
+		*do_update = true;
 
 	if (data_type != BCH_DATA_btree && p.ptr.gen != g->gen)
-			goto next;
+		goto out;
 
 	if (fsck_err_on(bucket_data_type_mismatch(g->data_type, data_type),
 			c, ptr_bucket_data_type_mismatch,
@@ -575,7 +570,7 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			g->dirty_sectors	= 0;
 			g->cached_sectors	= 0;
 		} else {
-				do_update = true;
+			*do_update = true;
 		}
 	}
 
@@ -589,7 +584,7 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 				(u64) p.ec.idx,
 				(printbuf_reset(&buf),
 				 bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
-				do_update = true;
+			*do_update = true;
 
 		if (fsck_err_on(m && m->alive && !bch2_ptr_matches_stripe_m(m, p), c,
 				ptr_to_incorrect_stripe,
@@ -598,10 +593,33 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 				(u64) p.ec.idx,
 				(printbuf_reset(&buf),
 				 bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
-				do_update = true;
+			*do_update = true;
 	}
-next:
+out:
+fsck_err:
 	bch2_dev_put(ca);
+	printbuf_exit(&buf);
+	return ret;
+}
+
+int bch2_check_fix_ptrs(struct btree_trans *trans,
+			enum btree_id btree, unsigned level, struct bkey_s_c k,
+			enum btree_iter_update_trigger_flags flags)
+{
+	struct bch_fs *c = trans->c;
+	struct bkey_ptrs_c ptrs_c = bch2_bkey_ptrs_c(k);
+	const union bch_extent_entry *entry_c;
+	struct extent_ptr_decoded p = { 0 };
+	bool do_update = false;
+	struct printbuf buf = PRINTBUF;
+	int ret = 0;
+
+	percpu_down_read(&c->mark_lock);
+
+	bkey_for_each_ptr_decode(k.k, ptrs_c, p, entry_c) {
+		ret = bch2_check_fix_ptr(trans, k, p, entry_c, &do_update);
+		if (ret)
+			goto err;
 	}
 
 	if (do_update) {
@@ -716,7 +734,6 @@ int bch2_check_fix_ptrs(struct btree_trans *trans,
 			bch2_btree_node_update_key_early(trans, btree, level - 1, k, new);
 	}
 err:
-fsck_err:
 	percpu_up_read(&c->mark_lock);
 	printbuf_exit(&buf);
 	return ret;