debugfs: stat /a
Inode: 12   Type: regular    Mode:  0644   Flags: 0x0
Generation: 1573716129    Version: 0x00000000:00000001
User:     0   Group:     0   Size: 524288
File ACL: 0    Directory ACL: 0
Links: 1   Blockcount: 1030
Fragment:  Address: 0    Number: 0    Size: 0
 ctime: 0x5457f87a:62ae2980 -- Mon Nov  3 21:49:46 2014
 atime: 0x5457f87a:61ba0598 -- Mon Nov  3 21:49:46 2014
 mtime: 0x5457f87a:62ae2980 -- Mon Nov  3 21:49:46 2014
crtime: 0x5457f87a:61ba0598 -- Mon Nov  3 21:49:46 2014
Size of extra inode fields: 28
BLOCKS:
(0-11):1025-1036, (IND):24, (12-267):1037-1292, (DIND):25, (IND):41, (268-511):1293-1536
TOTAL: 515

debugfs: ex /zero
Level Entries       Logical      Physical Length Flags
 0/ 1   1/  1     0 -     8    28              9
 1/ 1   1/  4     0 -     0    27 -    27      1 
 1/ 1   2/  4     2 -     2    29 -    29      1 
 1/ 1   3/  4     4 -     4    31 -    31      1 
 1/ 1   4/  4     6 -     6    33 -    33      1 
Pass 1: Checking inodes, blocks, and sizes
Pass 1E: Optimizing extent trees
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information

test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
test_filesys: 13/128 files (15.4% non-contiguous), 574/2048 blocks
Exit status is 1