resize2fs 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 479 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
resize2fs test.img -b
Converting the filesystem to 64-bit.
The filesystem on test.img is now 524288 (1k) blocks long.

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 dir_index filetype meta_bg extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
+Filesystem features:      has_journal ext_attr dir_index filetype meta_bg extent 64bit flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
 Default mount options:    user_xattr acl
 Filesystem state:         clean
 Errors behavior:          Continue
@@ -10,11 +10,12 @@
 Inode count:              65536
 Block count:              524288
 Reserved block count:     26214
-Free blocks:              858
+Free blocks:              852
 Free inodes:              65046
 First block:              1
 Block size:               1024
 Fragment size:            1024
+Group descriptor size:    64
 Blocks per group:         8192
 Fragments per group:      8192
 Inodes per group:         1024
@@ -54,9 +55,9 @@
 12:98305:-1:-1:15:31:3107
 13:106497:-1:-1:16:32:3363
 14:114689:-1:-1:17:33:3619
-15:122881:-1:-1:18:34:3875
-16:131073:-1:-1:131073:131089:131105
-17:139265:-1:-1:131074:131090:131361
+15:122881:-1:122881:18:34:3875
+16:131073:-1:131073:135201:131089:131105
+17:139265:-1:139265:131074:131090:131361
 18:147457:-1:-1:131075:131091:131617
 19:155649:-1:-1:131076:131092:131873
 20:163841:-1:-1:131077:131093:132129
@@ -86,9 +87,9 @@
 44:360449:-1:-1:262158:262174:265250
 45:368641:-1:-1:262159:262175:265506
 46:376833:-1:-1:262160:262176:265762
-47:385025:-1:-1:262161:262177:266018
-48:393217:-1:-1:393217:393233:393249
-49:401409:401409:-1:393218:393234:393505
+47:385025:-1:385025:262161:262177:266018
+48:393217:-1:393217:397345:393233:393249
+49:401409:401409:401410:393218:393234:393505
 50:409601:-1:-1:393219:393235:393761
 51:417793:-1:-1:393220:393236:394017
 52:425985:-1:-1:393221:393237:394273
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