2002-01-22 14:06:42

by Michael Zhu

Subject: something about ext2 file system

Hello, I have some questions about ext2 file system.

1.How the directory and file name information are
stored on the disk? I mean is there a range of blocks
set at disk format or intialize time for this kind of
information?

2.I know in ext2 the whole disk is made up of the boot
block and some block groups. Each block groups
contains super block,group descriptors,data block
bitmap,inode bitmap,inode table and data blocks. The
directory and file name information are stored in
which part? In the data blocks?

3.Are file names and other metadata put into the same
range of blocks?

4.Where can I find some detail information about ext2
fiel system?

Thanks in advance.

Michael


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2002-01-22 19:23:10

by Andreas Dilger

Subject: Re: something about ext2 file system

On Jan 22, 2002 09:06 -0500, Michael Zhu wrote:
> 1.How the directory and file name information are
> stored on the disk? I mean is there a range of blocks
> set at disk format or intialize time for this kind of
> information?

Like most Unix filesystems, directories are just a special form of
a file, so they are stored in data blocks. See the structure
ext2_dir_entry_2 in linux/include/ext2_fs.h for more info on the
exact layout on disk.

> 2.I know in ext2 the whole disk is made up of the boot
> block and some block groups. Each block groups
> contains super block,group descriptors,data block
> bitmap,inode bitmap,inode table and data blocks. The
> directory and file name information are stored in
> which part? In the data blocks?

As above - directories are
>
> 3.Are file names and other metadata put into the same
> range of blocks?

No. Only the filename and inode number are in the directory, along
with some data about the length of the directory entry.

> 4.Where can I find some detail information about ext2
> fiel system?

There are several papers which describe the structure of ext2
available on the internet. One is probably available from
http://e2fsprogs.sourceforge.net/

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/