Help : e2fsprogs

Christopher Chan christopher.chan at
Fri Feb 26 05:42:09 UTC 2010

On Friday, February 26, 2010 01:00 PM, MirJafar Ali wrote:
> Hello,
> Hope you will forgive me for asking some very simple question about
> e2fsprogs. I am very new to the kernel as
> well as file system programming.
> My task is to collect superblock, inode, bitmap ( or free list)
> information from ext2/ext3 filesysteam. After searching
> the google, I came to know about e2fsprogs, which I was able to install
> and use at least "dumpe2fs" utility. This
> utility do not provide timestamp of each allocated inode and I am
> thinking of modifying source code of e2fsprogs.

Use stat. However, not all timestamps will necessarily be updated like 
when there are mount options to exclude access timestamps

> My two questions are:
> 1.   Is it correct to use "dumpe2fs" program and modify for timestamp ?

See above.

> 2.   I could not understand the main purpose of e2fsprogs. Am I correct
> to assume that this program extract information
>       from the existing ext2/ext3 filesystem. Why there are ext2_inode
> datastructure defined in these programs ? Why couldn't
>       these programs read existing datastructures of inode ?

ext3 filesystems are readable by the ext2 filesystem driver because 
there are no changes to the datastructure. ext3 mainly adds a journal by 
reserving inode 8 for the journal (which is why it is best done at 
creation time to get sequential blocks allocated) and some other 
features that have been tacked on over time.

> 3.  Are these user level or kernel level programs ?

It won't be kernel level if you run it on the commandline would it? You 
can use a user level program to adjust or manipulate something in the 
kernel like using iptables to manipulate netfilter.

> 4.  I want to have my own policies of allocatiing datablocks in some
> cylinder group instead of using ext2 default policy ? What
>      should I do for that ?

Read ext2/3/4 code? Clone and modify the code, give it another name, 
test that on some free space? Oh, go ask on an appropriate list.

> I know, these must be silly questions, but I will learn from your response.

They are silly because you are asking in the WRONG location. This is a 
technical support list. Not even a filesystem enthusiasts list let alone 
a filesystem developers list.

More information about the ubuntu-users mailing list