tune2fs metadata_csum test
Creating filesystem with 524288 1k blocks and 65536 inodes
Superblock backups stored on blocks: 
	8193, 24577, 40961, 57345, 73729, 204801, 221185, 401409

Allocating group tables:      done                            
Writing inode tables:      done                            
Creating journal (16384 blocks): done
Creating 477 huge file(s) with 1024 blocks each: done
Writing superblocks and filesystem accounting information:      done

Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information

Exit status is 0
tune2fs -O metadata_csum test.img

This operation requires a freshly checked filesystem.

Please run e2fsck -fD on the filesystem.

Exit status is 0
test_filesys was not cleanly unmounted, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 3A: Optimizing directories
Pass 4: Checking reference counts
Pass 5: Checking group summary information


Change in FS metadata:
@@ -2,7 +2,7 @@
 Last mounted on:          <not available>
 Filesystem magic number:  0xEF53
 Filesystem revision #:    1 (dynamic)
-Filesystem features:      has_journal ext_attr resize_inode dir_index filetype extent 64bit flex_bg sparse_super large_file huge_file dir_nlink extra_isize
+Filesystem features:      has_journal ext_attr resize_inode dir_index filetype extent 64bit flex_bg sparse_super large_file huge_file dir_nlink extra_isize metadata_csum
 Default mount options:    user_xattr acl
 Filesystem state:         clean
 Errors behavior:          Continue
@@ -10,7 +10,7 @@
 Inode count:              65536
 Block count:              524288
 Reserved block count:     26214
-Free blocks:              571
+Free blocks:              568
 Free inodes:              65048
 First block:              1
 Block size:               1024
@@ -33,6 +33,7 @@
 Journal inode:            8
 Default directory hash:   half_md4
 Journal backup:           inode blocks
+Checksum type:            crc32c
 Journal features:         (none)
 Journal size:             16M
 Journal length:           16384
@@ -40,24 +41,24 @@
 Journal start:            0
 
 
-Group 0: (Blocks 1-8192)
+Group 0: (Blocks 1-8192) [ITABLE_ZEROED]
   Primary superblock at 1, Group descriptors at 2-5
   Reserved GDT blocks at 6-261
   Block bitmap at 262 (+261)
   Inode bitmap at 278 (+277)
   Inode table at 294-549 (+293)
-  21 free blocks, 536 free inodes, 2 directories
-  Free blocks: 4413-4433
+  18 free blocks, 536 free inodes, 2 directories, 536 unused inodes
+  Free blocks: 4413, 4417-4433
   Free inodes: 489-1024
-Group 1: (Blocks 8193-16384)
+Group 1: (Blocks 8193-16384) [INODE_UNINIT, ITABLE_ZEROED]
   Backup superblock at 8193, Group descriptors at 8194-8197
   Reserved GDT blocks at 8198-8453
   Block bitmap at 263 (bg #0 + 262)
   Inode bitmap at 279 (bg #0 + 278)
   Inode table at 550-805 (bg #0 + 549)
-  0 free blocks, 1024 free inodes, 0 directories
+  0 free blocks, 1024 free inodes, 0 directories, 1024 unused inodes
   Free blocks: 
   Free inodes: 1025-2048
-Group 2: (Blocks 16385-24576)
+Group 2: (Blocks 16385-24576) [INODE_UNINIT, ITABLE_ZEROED]
   Block bitmap at 264 (bg #0 + 263)
   Inode bitmap at 280 (bg #0 + 279)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information

Exit status is 0