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, 2 insertions, 1 deletions

diff --git a/sys/sys/file.h b/sys/sys/file.h
index 207f227..6e04352 100644
--- a/sys/sys/file.h
+++ b/sys/sys/file.h
@@ -56,7 +56,7 @@ struct knote;
  */
 struct file {
 	LIST_ENTRY(file) f_list;/* list of active files */
-	short	f_flag;		/* see fcntl.h */
+	short	f_FILLER3;	/* (old f_flag) */
 #define	DTYPE_VNODE	1	/* file */
 #define	DTYPE_SOCKET	2	/* communications endpoint */
 #define	DTYPE_PIPE	3	/* pipe */
@@ -93,6 +93,7 @@ struct file {
 				 */
 	off_t	f_offset;
 	caddr_t	f_data;		/* vnode or socket */
+	u_int	f_flag;		/* see fcntl.h */
 };
 
 #ifdef MALLOC_DECLARE