Where do you store user context in Linux character drivers?

Question

It's been a while since I worked on a Linux kernel module, and I seem to remember that there was a place to stash context in your open() open implementation that would be available in your other file_operations... For example, if I want to maintain some state associated with everyone that opens my device node, if either the inode structure or the file structure that is passed to all the file_operations functions had a void* I could fill, I could very easily support any number of users.... Is this possible?

Answer 1

Found the answer. the "struct file*" that's passed to all the file_operations functions has a field called "private_data"... It's a void*, so you can populate in open, use it in read(), write() and ioctl() and free it in release()..