Size return 0 with standard blockDevices in FileBackend which leads to mount error on client side

[efrasyab]

if Size() function of the FileBackend would be revised as below, standard block devices could be mounted successfully from client side.

func (b *FileBackend) Size() (int64, error) { stat, err := b.file.Seek(0,2) if err != nil { return -1, err } return stat, nil }

[pojntfx]

Thank you! Implemented in 2d78be2564f3835178508cb61c0a84d562f80364