cmd: fix openControl for binded mount point (#3858)

cmd/rmr.go

@@ -42,14 +42,17 @@ $ juicefs rmr /mnt/jfs/foo`,
 	}
 }
 
-func openController(path string) (*os.File, error) {
-	mp, err := findMountpoint(path)
+func openController(dpath string) (*os.File, error) {
+	st, err := os.Stat(dpath)
 	if err != nil {
 		return nil, err
 	}
-	fp, err := os.OpenFile(filepath.Join(mp, ".jfs.control"), os.O_RDWR, 0)
+	if !st.IsDir() {
+		dpath = filepath.Dir(dpath)
+	}
+	fp, err := os.OpenFile(filepath.Join(dpath, ".jfs.control"), os.O_RDWR, 0)
 	if os.IsNotExist(err) {
-		fp, err = os.OpenFile(filepath.Join(mp, ".control"), os.O_RDWR, 0)
+		fp, err = os.OpenFile(filepath.Join(dpath, ".control"), os.O_RDWR, 0)
 	}
 	return fp, err
 }

cmd/warmup.go

@@ -192,16 +192,23 @@ func warmup(ctx *cli.Context) error {
 
 	// find mount point
 	first := paths[0]
-	mp, err := findMountpoint(first)
-	if err != nil {
-		return err
-	}
-	controller, err := openController(mp)
+	controller, err := openController(first)
 	if err != nil {
 		return fmt.Errorf("open control file for %s: %s", first, err)
 	}
 	defer controller.Close()
 
+	mp := first
+	for ; mp != "/"; mp = filepath.Dir(mp) {
+		inode, err := utils.GetFileInode(mp)
+		if err != nil {
+			logger.Fatalf("lookup inode for %s: %s", mp, err)
+		}
+		if inode == uint64(meta.RootInode) {
+			break
+		}
+	}
+
 	threads := ctx.Uint("threads")
 	if threads == 0 {
 		logger.Warnf("threads should be larger than 0, reset it to 1")