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 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
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 resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg 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 uninit_bg dir_nlink extra_isize
 Default mount options:    user_xattr acl
 Filesystem state:         clean
 Errors behavior:          Continue
@@ -15,7 +15,8 @@
 First block:              1
 Block size:               1024
 Fragment size:            1024
-Reserved GDT blocks:      256
+Group descriptor size:    64
+Reserved GDT blocks:      254
 Blocks per group:         8192
 Fragments per group:      8192
 Inodes per group:         1024
@@ -40,16 +41,16 @@
 
 
 group:block:super:gdt:bbitmap:ibitmap:itable
-0:1:1:2-3:260:276:292
-1:8193:8193:8194-8195:261:277:548
+0:1:1:2-5:260:276:292
+1:8193:8193:8194-8197:261:277:548
 2:16385:-1:-1:262:278:804
-3:24577:24577:24578-24579:263:279:1060
+3:24577:24577:24578-24581:263:279:1060
 4:32769:-1:-1:264:280:1316
-5:40961:40961:40962-40963:265:281:1572
+5:40961:40961:40962-40965:265:281:1572
 6:49153:-1:-1:266:282:1828
-7:57345:57345:57346-57347:267:283:2084
+7:57345:57345:57346-57349:267:283:2084
 8:65537:-1:-1:268:284:2340
-9:73729:73729:73730-73731:269:285:2596
+9:73729:73729:73730-73733:269:285:2596
 10:81921:-1:-1:270:286:2852
 11:90113:-1:-1:271:287:3108
 12:98305:-1:-1:272:288:3364
@@ -65,9 +66,9 @@
 22:180225:-1:-1:131079:131095:132641
 23:188417:-1:-1:131080:131096:132897
 24:196609:-1:-1:131081:131097:133153
-25:204801:204801:204802-204803:131082:131098:133409
+25:204801:204801:204802-204805:131082:131098:133409
 26:212993:-1:-1:131083:131099:133665
-27:221185:221185:221186-221187:131084:131100:133921
+27:221185:221185:221186-221189:131084:131100:133921
 28:229377:-1:-1:131085:131101:134177
 29:237569:-1:-1:131086:131102:134433
 30:245761:-1:-1:131087:131103:134689
@@ -89,7 +90,7 @@
 46:376833:-1:-1:262159:262175:265761
 47:385025:-1:-1:262160:262176:266017
 48:393217:-1:-1:393217:393233:393249
-49:401409:401409:401410-401411:393218:393234:393505
+49:401409:401409:401410-401413:393218:393234:393505
 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