VFS concurrency control and initialization

[Benjamin Rutt <rutt+news@cis.ohio-state.edu>]

I'm starting to hack on VFS, my first kernel hacking project, and have
a couple of preliminary questions.

First, I'm trying to modify 'sys_open' from fs/open.c, representing
the 'open' system call.  I'd like to make an update to a global data
structure on every open system call.  Updates to this data structure
will need to be mutually exclusive in order to avoid data structure
corruption.  Do I need to initiate some form of concurrency control,
or does 'sys_open' already happen atomically?

Secondly, I'm not exactly sure where to declare and initialize the
global data structure I'm referring to in the above paragraph.  I
expect it should be initialized when VFS is initialized.  Where should
I look for VFS init?  I'm noticing that the buffer cache is
initialized in 'buffer_init' from fs/buffer.c, but am looking for a
general place to initialize my global data structure.

Thanks,
-- 
Benjamin

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