QNX EFS Driver

[Kai Bankett <chaosman@ontika.net>]

Hi together,

I did not lazily put my legs up ... (in case someone got that impression)
Had to reverse engineer another QNX filesystem first. (for what I want 
to achieve with all that QNX stuff)
However, at that stage I greatly could need some inspiration by you on 
how to improve driver quality. (not the nicest peace of code I ever 
wrote ...)

The QNX EFS Filesystem is used in flash devices and created during the 
build process. The EFS file is the flashed onto the flash chips in 
embedded designs.

Due to the fact that the QNX EFS Filesystem is not using any fixed 
blocks and just some fixed structures, I started fighting against the 
buffer head blocksize.
I think I could pretty up the code a lot if there's any way to read N 
Bytes from a device at position X.
Already started to look around, but could not really find something 
giving me direct position access to a device.

Well, maybe there's a even better way to solve things? (so feedback 
very, very welcome)

But first here's the patch (as it currently is):
http://a6.ontika.net/patches/efs-patch-v3.gz

At least I would be extremly thankful if someone could point me some 
direction on how to better solve the chunkreading in qnxefs_file_read().
It's currently buffer_head based with a blocksize of 512kb. The QNX EFS 
- at least the files I got hold of - uses 16384 byte Blocks in 262144 
byte logical units.
So a file is split into chunks of up to 0x4000 size, but that chunks can 
vary in size. (in case of the end of a logical unit, file end etc.)

Hope I am not boring you too much with all my QNX stuff ;)

Thanks,

Kai