File system development question

File system development question

[Racz Zoltan]

Hi.

Some days ago I started studying the linux VFS api, and until now I 
wrote a mountable only file system. I would like to go further than 
that, but I didn`t find any good documentations on google. Some of them 
are incomplete, others are written for the 2.4 kernel series etc. Can 
somebody recommend a good book or documentation about file system 
development on the 2.6 or 3.x kernel series? It`s not a problem if it 
doesn`t contain a full source code (I don`t want to only copy paste code 
written by someone else, compile it, and voila, I`m a kernel 
developer).  Reading the vfs api,or source files from the kernel is 
fine, but without knowing step by step what do I need to do, I only end 
up with kernel panics, and it is really hard to figure out what happened.

Thank you.

File system development question

[Prashant Shah]

Hi,

On Mon, Jan 21, 2013 at 4:53 PM, Racz Zoltan <racz.zoli@gmail.com> wrote:
> Hi.
>
> Some days ago I started studying the linux VFS api, and until now I
> wrote a mountable only file system. I would like to go further than
> that, but I didn`t find any good documentations on google.

Try older versions of squashfs.

http://sourceforge.net/projects/squashfs/files/squashfs/

On centos 5.8 kernel (2.6.18) its only two .c files.

Regards.

File system development question

[Racz Zoli]

Hi.

First of all I would like to apologize for writing about my question
on this mailing list (I know this place isn`t for newbies), but I`ve
sent multiple emails to the kernelnewbies mailing list a week ago, and
nobody answered since. I posted my question on linux forums, but the
result was pretty much the same.

I started learning file system development some time ago. I`ve read
the section about block devices in Andrew Tanenbaum`s Operating system
design and implementation book and many other documentations to learn
how block devices actually work, but now I`m having a hard time
implementing what I`ve learnt using the linux vfs api. Because of the
complexity of vfs, and the lack of detailed documentation I`m
progressing really slow, and many times, after I write a chunk of
code, I only end up with kernel panics, or segfaults and find out days
later that I didn`t initialize something the api needed. I`ve spent
days searching on the internet for tutorials and howtos, but many of
them are incomplete, some of them don`t even compile, or simply they
are written for older kernel versions, and because of the interface
changes in the vfs api they are pretty much useless. On one of my
machines I`m running the 2.6.32 series and 3.6.xx on the other one.

Can somebody help me with links to documentations, books or howtos
about how and where to start file system development in linux? It
doesn`t necessarily need to contain a full source code. I don`t want
to only copy paste somebody else`s code, and voila, I`m a kernel
developer. I would like to understand step by step how the vfs api is
actually working, how to do things, and maybe in the future to be able
to write my own file system, or to contribute to an existing one.

Thank you in advance.
Zoli.

Re: File system development question

[David Sterba]

On Tue, Jan 22, 2013 at 11:39:31PM +0200, Racz Zoli wrote:
> Can somebody help me with links to documentations, books or howtos
> about how and where to start file system development in linux? It
> doesn`t necessarily need to contain a full source code. I don`t want
> to only copy paste somebody else`s code, and voila, I`m a kernel
> developer. I would like to understand step by step how the vfs api is
> actually working, how to do things, and maybe in the future to be able
> to write my own file system, or to contribute to an existing one.

You may find this book useful

Practical File System Design: The Be File System
http://www.nobius.org/~dbg/practical-file-system-design.pdf

or for specific topics

Understanding the Linux Kernel
http://ceata.org/~tct/resurse/utlk.pdf

Where the APIs changed, look into existing implementations, I don't know
about any book that describes recent status of linux internals.

david