This patch implements O_DIRECT about 80% of the way. It takes a patchset

Tor created a while ago, removes the raw I/O piece (that has cache coherency
problems), and adds a buffer cache / VM freeing piece.

Essentially this patch causes O_DIRECT I/O to not be left in the cache, but
does not prevent it from going through the cache, hence the 80%.  For
the last 20% we need a method by which the I/O can be issued directly to
buffer supplied by the user process and bypass the buffer cache entirely,
but still maintain cache coherency.

I also have the code working under -stable but the changes made to sys/file.h
may not be MFCable, so an MFC is not on the table yet.

Submitted by:	tegge, dillon

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index e1c1cc4..6bc7266 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -421,6 +421,7 @@ vm_page_t vm_page_alloc __P((vm_object_t, vm_pindex_t, int));
 vm_page_t vm_page_grab __P((vm_object_t, vm_pindex_t, int));
 void vm_page_cache __P((register vm_page_t));
 int vm_page_try_to_cache __P((vm_page_t));
+int vm_page_try_to_free __P((vm_page_t));
 void vm_page_dontneed __P((register vm_page_t));
 static __inline void vm_page_copy __P((vm_page_t, vm_page_t));
 static __inline void vm_page_free __P((vm_page_t));