bcachefs: Fix a bug when shutting down before allocator started

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

fs/bcachefs/alloc_background.c

@@ -1535,6 +1535,8 @@ int bch2_fs_allocator_start(struct bch_fs *c)
 		}
 	}
 
+	set_bit(BCH_FS_ALLOCATOR_RUNNING, &c->flags);
+
 	return bch2_alloc_write(c, false, &wrote);
 }
 

fs/bcachefs/bcachefs.h

@@ -477,6 +477,7 @@ enum {
 	/* startup: */
 	BCH_FS_ALLOC_READ_DONE,
 	BCH_FS_ALLOCATOR_STARTED,
+	BCH_FS_ALLOCATOR_RUNNING,
 	BCH_FS_INITIAL_GC_DONE,
 	BCH_FS_FSCK_DONE,
 	BCH_FS_STARTED,

fs/bcachefs/super.c

@@ -191,6 +191,9 @@ static void __bch2_fs_read_only(struct bch_fs *c)
 	 */
 	bch2_journal_flush_all_pins(&c->journal);
 
+	if (!test_bit(BCH_FS_ALLOCATOR_RUNNING, &c->flags))
+		goto allocator_not_running;
+
 	do {
 		ret = bch2_alloc_write(c, false, &wrote);
 		if (ret) {
@@ -219,10 +222,12 @@ static void __bch2_fs_read_only(struct bch_fs *c)
 		closure_wait_event(&c->btree_interior_update_wait,
 				   !bch2_btree_interior_updates_nr_pending(c));
 	} while (wrote);
-
+allocator_not_running:
 	for_each_member_device(ca, c, i)
 		bch2_dev_allocator_stop(ca);
 
+	clear_bit(BCH_FS_ALLOCATOR_RUNNING, &c->flags);
+
 	bch2_fs_journal_stop(&c->journal);
 
 	/* XXX: mark super that alloc info is persistent */
@@ -349,6 +354,8 @@ const char *bch2_fs_read_write(struct bch_fs *c)
 			goto err;
 		}
 
+	set_bit(BCH_FS_ALLOCATOR_RUNNING, &c->flags);
+
 	err = "error starting btree GC thread";
 	if (bch2_gc_thread_start(c))
 		goto err;