Merge pull request #4590 from renard/optimize-mount-failure

mount: detect mountpoint does not exist before opening the repository

changelog/unreleased/pull-4590

@@ -0,0 +1,7 @@
+Enhancement: `mount` tests mountpoint existence before opening the repository
+
+The restic `mount` command now checks for the existence of the
+mountpoint before opening the repository, leading to quicker error
+detection.
+
+https://github.com/restic/restic/pull/4590

cmd/restic/cmd_mount.go

@@ -113,6 +113,15 @@ func runMount(ctx context.Context, opts MountOptions, gopts GlobalOptions, args
 		return errors.Fatal("wrong number of parameters")
 	}
 
+	mountpoint := args[0]
+
+	// Check the existence of the mount point at the earliest stage to
+	// prevent unnecessary computations while opening the repository.
+	if _, err := resticfs.Stat(mountpoint); errors.Is(err, os.ErrNotExist) {
+		Verbosef("Mountpoint %s doesn't exist\n", mountpoint)
+		return err
+	}
+
 	debug.Log("start mount")
 	defer debug.Log("finish mount")
 
@@ -136,12 +145,6 @@ func runMount(ctx context.Context, opts MountOptions, gopts GlobalOptions, args
 		return err
 	}
 
-	mountpoint := args[0]
-
-	if _, err := resticfs.Stat(mountpoint); errors.Is(err, os.ErrNotExist) {
-		Verbosef("Mountpoint %s doesn't exist\n", mountpoint)
-		return err
-	}
 	mountOptions := []systemFuse.MountOption{
 		systemFuse.ReadOnly(),
 		systemFuse.FSName("restic"),