test@localhost:~$ sudo dumpe2fs /dev/mmcblk0p13
dumpe2fs 1.42.13 (17-May-2015)
Filesystem volume name:   writable
Last mounted on:          /tmpmnt_writable
Filesystem UUID:          f458374b-6207-355a-a8ab-2f03ffb0421b
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal ext_attr resize_inode filetype needs_recovery extent sparse_super large_file uninit_bg
Filesystem flags:         unsigned_directory_hash 
Default mount options:    (none)
Filesystem state:         clean
Errors behavior:          Remount read-only
Filesystem OS type:       Linux
Inode count:              1048576
Block count:              4194304
Reserved block count:     0
Free blocks:              4015227
Free inodes:              1047986
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      1023
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8192
Inode blocks per group:   512
Last mount time:          Thu Jan  1 03:42:04 1970
Last write time:          Thu Jan  1 03:42:04 1970
Mount count:              27
Maximum mount count:      -1
Last checked:             Thu Jan  1 00:00:00 1970
Check interval:           0 (<none>)
Lifetime writes:          1696 kB
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:	          256
Required extra isize:     28
Desired extra isize:      28
Journal inode:            8
Default directory hash:   tea
Journal backup:           inode blocks
Journal features:         (none)
Journal size:             128M
Journal length:           32768
Journal sequence:         0x00000301
Journal start:            1