OS : freebsd 8.2 release

As of now we have understood that any program uses struct stat structure to store temporary inode info and display it. The struct stat structure gets info from struct inode (defined in inode.h) which in turn gets info from struct dinode. The struct dinode is (or may be, I am not sure) is the actual physical representation of the inode structure.

I also tried studying ls.c source code. I found that it uses another important structures struct FTS and struct FTSENT for traversing the file system hierarchy using functions defined in fts.c. Now the problem is that fts.c uses systemcalls like fstat() and open() for accessing inode information
I'm trying to find how the information is retrieved from dinode and printed on the console or to the file. Once I know how it is retrieved, I'll try to add a field to dinode structure last_modified_by i.e it would have the username who lastly modified that file. I'll probably try to modify ls.c also to display information on console.

I think the path for the system calls are two fold:
1. Filesystem Independent system calls present in /usr/src/lib/libstand
2. Filesystem Dependent system calls present in /usr/src/lib/libstand/<file_system.c>

I have read /usr/src/lib/libstand/stand.h which I think is the periphery of Platform Independence. I t has a structure called struct fs_ops which has function pointers for system calls like *open(), *stat(), *fstat() etc.
These function pointers are made to point to actual system calls from different Platform Dependent file systems like ext2fs , ufs etc.
This is done by the open system call ( by reading from the struct open_file files] and struct fs_ops *file_system[).
I think if we want to add thi field for a particular file system, then I should try to make changes in file system C files like ufs.c and vfs.c ( and so on ...)

Now I was thinking that modifying already implemented file systems is a messy thing. So, I was planning to make my own file system. This file system code will only include the necessary fs_ops (File system Operations i.e. system calls) and putting the appropriate pointers in stand.h. Am I thinking right?

I read an IBM Developer Forum for FUSE which explained how to create a File System in User Space which explained something very similar. The link is as follows:
http://www.ibm.com/developerworks/linux/library/l-fuse/

Can you please suggest if I am on the right track or not. And also can you suggest some links I can read, that might help me for the same( ie For creating or modifying the file system)