bees: initialize context in the correct order

We cannot use BeesContext::roots() until after
BeesContext::set_root_path() has been called.
Save up the parameter settings until then.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

src/bees-context.cc

@@ -773,11 +773,42 @@ BeesResolveAddrResult::BeesResolveAddrResult()
 {
 }
 
+void
+BeesContext::wait_for_balance()
+{
+	Timer balance_timer;
+	BEESNOTE("WORKAROUND: waiting for balance to stop");
+	while (true) {
+		btrfs_ioctl_balance_args args;
+		memset_zero<btrfs_ioctl_balance_args>(&args);
+		const int ret = ioctl(root_fd(), BTRFS_IOC_BALANCE_PROGRESS, &args);
+		if (ret < 0) {
+			// Either can't get balance status or not running, exit either way
+			break;
+		}
+
+		if (!(args.state & BTRFS_BALANCE_STATE_RUNNING)) {
+			// Balance not running, doesn't matter if paused or cancelled
+			break;
+		}
+
+		BEESLOGDEBUG("WORKAROUND: Waiting " << balance_timer << "s for balance to stop");
+		sleep(BEES_BALANCE_POLL_INTERVAL);
+	}
+}
+
 BeesResolveAddrResult
 BeesContext::resolve_addr_uncached(BeesAddress addr)
 {
 	THROW_CHECK1(invalid_argument, addr, !addr.is_magic());
 	THROW_CHECK0(invalid_argument, !!root_fd());
+
+	// Is there a bug where resolve and balance cause a crash (BUG_ON at fs/btrfs/ctree.c:1227)?
+	// Apparently yes, and more than one.
+	// Wait for the balance to finish before we run LOGICAL_INO
+	wait_for_balance();
+
+	// Time how long this takes
 	Timer resolve_timer;
 
 	// There is no performance benefit if we restrict the buffer size.

src/bees.cc

@@ -667,6 +667,7 @@ bees_main(int argc, char *argv[])
 	unsigned thread_min = 0;
 	double load_target = 0;
 	bool workaround_btrfs_send = false;
+	BeesRoots::ScanMode root_scan_mode = BeesRoots::SCAN_MODE_ZERO;
 
 	// Configure getopt_long
 	static const struct option long_options[] = {
@@ -735,7 +736,7 @@ bees_main(int argc, char *argv[])
 				load_target = stod(optarg);
 				break;
 			case 'm':
-				bc->roots()->set_scan_mode(static_cast<BeesRoots::ScanMode>(stoul(optarg)));
+				root_scan_mode = static_cast<BeesRoots::ScanMode>(stoul(optarg));
 				break;
 			case 'p':
 				crucible::set_relative_path("");
@@ -806,11 +807,16 @@ bees_main(int argc, char *argv[])
 	BEESLOGNOTICE("setting worker thread pool maximum size to " << thread_count);
 	TaskMaster::set_thread_count(thread_count);
 
+	// Set root path
+	string root_path = argv[optind++];
+	BEESLOGNOTICE("setting root path to '" << root_path << "'");
+	bc->set_root_path(root_path);
+
 	// Workaround for btrfs send
 	bc->roots()->set_workaround_btrfs_send(workaround_btrfs_send);
 
-	// Create a context and start crawlers
-	bc->set_root_path(argv[optind++]);
+	// Set root scan mode
+	bc->roots()->set_scan_mode(root_scan_mode);
 
 	BeesThread status_thread("status", [&]() {
 		bc->dump_status();

src/bees.h

@@ -117,6 +117,9 @@ const size_t BEES_TRANSID_FACTOR = 10;
 // The actual limit in LOGICAL_INO seems to be 2730, but let's leave a little headroom
 const size_t BEES_MAX_EXTENT_REF_COUNT = 2560;
 
+// Wait this long for a balance to stop
+const double BEES_BALANCE_POLL_INTERVAL = 60.0;
+
 // Flags
 const int FLAGS_OPEN_COMMON   = O_NOFOLLOW | O_NONBLOCK | O_CLOEXEC | O_NOATIME | O_LARGEFILE | O_NOCTTY;
 const int FLAGS_OPEN_DIR      = FLAGS_OPEN_COMMON | O_RDONLY | O_DIRECTORY;
@@ -716,6 +719,7 @@ class BeesContext : public enable_shared_from_this<BeesContext> {
 	void set_root_fd(Fd fd);
 
 	BeesResolveAddrResult resolve_addr_uncached(BeesAddress addr);
+	void wait_for_balance();
 
 	BeesFileRange scan_one_extent(const BeesFileRange &bfr, const Extent &e);
 	void rewrite_file_range(const BeesFileRange &bfr);