source code questions

[Artur Grabowski]

From: Cheng Jin <chengjin at eecs.umich.edu>
Subject: source code questions
Date: Wed, 25 Mar 1998 16:10:20 -0500 (EST)

> Hi, guys.
> 
> I have a few more questions about the kernel xfs source code.
> 
> >From what I understand
> 
> a "read" syscall get to translate to "vn_read" for reading a file,
> and "vn_read" dispatch the call to the specific underlying fs read using 
> infomation store in the vnode.  In the case of xfs, "xfs_read" would be
> called.  

Right.

> Now I don't see where you check whether the vnode object is in
> memory or not.  

You don't have to do it. xfs_read is called only on vnodes that already are
in the memory. (if you call xfs_read on a vnode that isn't referenced
you have bigger problems than that.)

//art