Thank you very much for your attention! > u posted right...but i don't understand your question OK - that's reasonable, as I actually don't know, how to ask the right way. > u can: > > a. use FUSE > b. use libfs > c. use the model how ext3 and jfs worked together.....writing to ext3 > always entailed writing to jfs journalling. Hm, don't know, how much I already understood from the kernel stuff. One of the requirements to the "part", I'd like to create is, that it should be totally transparent to the users of the filesystem, means to existing applications. So I don't know, whether FUSE or libfs are right. Both are for userspace programs - aren't they? The whole story is to big for me to realize in one step, so let me try to explain, how I imagine the first step: I'd like to write a fs-module (like aufs or unionfs), let me call it simplefs, just to give it a name, wich works between userprogram and real filesystem. The final simplefs should manage several different "real" filesystems, where it has one private filesystem and all others are public. The private filesystem should be configured by the option-string of fstab. So an entry for my simplefs might be something like: /dev/virtual /mountPoint simplefs defaults,pd=/dev/sda1,pt=ext3,po="defaults" ... where pd stands for 'private device', pt for 'private type' and po for 'private options'. What I like to do in the first step is mounting that device on a subdir of /mountPoint i.e. /mountPoint/private Any directory operations should go to the mounted device as if that was mounted at /mountPoint and on a read-operation to a real file I would like to return 'hello world'. In the second step I'd like to realize a trigger to userspace before returning 'hello world'. All further steps will extend the read-function of a file - all directory or path-searching will stay unchanged. Currently I'm done with the option parsing and I also scanned the superblocks of all known devices to find the superblock of the given type. What I don't know, is how I should create the internal datastructures (from the strings I got from fstab) to mount the device and how I create a null-wrapper. I tried to wrap all functions with a kprint-message, but some functions crash the system. So it's not possible to just route the parameters to the other function. I think, it was a read-function with a __user pointer that crashed. Also I have a crash on unloading the module - it tell's me, that I did not unregister a kernel object, but I did not create any yet. So - there seems to be a lot of hidden stuff, which I have no idea on how to get rid of. And most tutorials about filesystems, I found, are outdated and broken. I hope, I was a bit better this time in explaining my problem :) kind regards Santiago -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
