First cut of NFS direct IO support.

- NFS direct IO completely bypasses the buffer and page caches.
  If a file is open for direct IO all caching is disabled.
- Direct IO for Directories will be addressed later.
- 2 new NFS directio related sysctls are added. One is a knob to
  disable NFS direct IO completely (direct IO is enabled by default).
  The other is to disallow mmaped IO on a file that has at least one
  O_DIRECT open (see the comment in nfs_vnops.c for more details).
  The default is to allow mmaps on a file that has O_DIRECT opens.

Submitted by:	Mohan Srinivasan mohans at yahoo-inc dot com
Obtained from:	Yahoo!

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/nfsclient/nfsnode.h b/sys/nfsclient/nfsnode.h
index 9889ea4..4c03183 100644
--- a/sys/nfsclient/nfsnode.h
+++ b/sys/nfsclient/nfsnode.h
@@ -127,6 +127,7 @@ struct nfsnode {
 	u_char			*n_name;	/* leaf name, for v4 OPEN op */
 	uint32_t		n_namelen;
 	daddr_t			ra_expect_lbn;
+	int			n_directio_opens;
 };
 
 #define n_atim		n_un1.nf_atim
@@ -149,6 +150,7 @@ struct nfsnode {
 #define	NCREATED	0x0800	/* Opened by nfs_create() */
 #define	NTRUNCATE	0x1000	/* Opened by nfs_setattr() */
 #define	NSIZECHANGED	0x2000  /* File size has changed: need cache inval */
+#define NNONCACHE	0x4000  /* Node marked as noncacheable */
 
 /*
  * Convert between nfsnode pointers and vnode pointers