constructing a struct aio and invoking VOP_READ() directly. This cleans
up the code a little, but also has the advantage of making sure almost
all vnode read/write access in the kernel goes through the helper
function, meaning that instrumentation of that helper function can impact
almost all relevant read/write operations. In this case, it permits us
to put MAC hooks into vn_rdwr() and not modify uipc_syscalls.c (yet).
In general, if helper vn_*() functions exist, they should be used in
preference to direct VOP's in system call service code.
Submitted by: green
Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs
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