importd: take a lock while we set up /var/lib/machines/

This way, we can safely set up the directories from two processes at the
same time, including machined and importd simultaneously.

diff --git a/src/shared/machine-pool.c b/src/shared/machine-pool.c
index add19bb5a10f86577ad79320fb70f106757c5fa1..7b17395d212b2bff7a82bd93b41f6c244739154f 100644 (file)
--- a/src/shared/machine-pool.c
+++ b/src/shared/machine-pool.c
@@ -161,6 +161,7 @@ fail:
 }
 
 int setup_machine_directory(sd_bus_error *error) {
+        _cleanup_release_lock_file_ LockFile lock_file = LOCK_FILE_INIT;
         struct loop_info64 info = {
                 .lo_flags = LO_FLAGS_AUTOCLEAR,
         };
@@ -170,6 +171,11 @@ int setup_machine_directory(sd_bus_error *error) {
         bool tmpdir_made = false, mntdir_made = false, mntdir_mounted = false;
         int r, nr = -1;
 
+        /* Make sure we only set the directory up once at a time */
+        r = make_lock_file("/run/systemd/machines.lock", LOCK_EX, &lock_file);
+        if (r < 0)
+                return r;
+
         r = check_btrfs();
         if (r < 0)
                 return sd_bus_error_set_errnof(error, r, "Failed to determine whether /var/lib/machines is located on btrfs: %m");