If you would like to find out file fragmentation information for specific file, use filefrag command that report on file fragmentation.
filefrag reports on how badly fragmented a particular file might be. It makes allowances for indirect blocks for ext2 and ext3 filesystems, but can be used on files for any filesystem.
For example see file fragmentation for /var/log/message file:
# filefrag -v /var/log/messages
Checking /var/log/messages Filesystem type is: ef53 Filesystem cylinder groups is approximately 9448 Blocksize of file /var/log/messages is 4096 File size of /var/log/messages is 72 (1 blocks) First block: 1841075 Last block: 1841075 /var/log/messages: 1 extent found