Forward port 930ff266f2 to cmount branch

compare checksums on upload/download via FUSE

cmd/mountlib/fs.go

@@ -33,9 +33,10 @@ var (
 
 // FS represents the top level filing system
 type FS struct {
-	f      fs.Fs
-	root   *Dir
-	noSeek bool // don't allow seeking if set
+	f          fs.Fs
+	root       *Dir
+	noSeek     bool // don't allow seeking if set
+	noChecksum bool // don't check checksums if set
 }
 
 // NewFS creates a new filing system and root directory
@@ -57,6 +58,12 @@ func (fsys *FS) NoSeek() *FS {
 	return fsys
 }
 
+// NoChecksum disables checksum checking
+func (fsys *FS) NoChecksum() *FS {
+	fsys.noChecksum = true
+	return fsys
+}
+
 // Root returns the root node
 func (fsys *FS) Root() (*Dir, error) {
 	fs.Debugf(fsys.f, "Root()")