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
mke2fs: Operation not supported for inodes containing extents while creating huge files
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
Extents are not enabled.  The file extent tree can be checksummed, whereas block maps cannot.  Not enabling extents reduces the coverage of metadata checksumming.  Re-run with -O extent to rectify.
64-bit filesystem support is not enabled.  The larger fields afforded by this feature enable full-strength checksumming.  Run resize2fs -b to rectify.
Exit status is 0

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 sparse_super large_file
+Filesystem features:      has_journal ext_attr resize_inode dir_index filetype sparse_super large_file metadata_csum
 Default mount options:    user_xattr acl
 Filesystem state:         clean
 Errors behavior:          Continue
@@ -29,6 +29,7 @@
 Journal inode:            8
 Default directory hash:   half_md4
 Journal backup:           inode blocks
+Checksum type:            crc32c
 Journal features:         (none)
 Journal size:             16M
 Journal length:           16384
@@ -36,7 +37,7 @@
 Journal start:            0
 
 
-Group 0: (Blocks 1-8192)
+Group 0: (Blocks 1-8192) [ITABLE_ZEROED]
   Primary superblock at 1, Group descriptors at 2-3
   Reserved GDT blocks at 4-259
   Block bitmap at 260 (+259)
@@ -45,7 +46,7 @@
   0 free blocks, 1013 free inodes, 2 directories
   Free blocks: 
   Free inodes: 12-1024
-Group 1: (Blocks 8193-16384)
+Group 1: (Blocks 8193-16384) [ITABLE_ZEROED]
   Backup superblock at 8193, Group descriptors at 8194-8195
   Reserved GDT blocks at 8196-8451
   Block bitmap at 8452 (+259)
@@ -54,6 +55,6 @@
   0 free blocks, 1024 free inodes, 0 directories
   Free blocks: 
   Free inodes: 1025-2048
-Group 2: (Blocks 16385-24576)
+Group 2: (Blocks 16385-24576) [ITABLE_ZEROED]
   Block bitmap at 16385 (+0)
   Inode bitmap at 16386 (+1)
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