NFS: Make stat() return updated mtimes after a write()

The SuS states that a call to write() will cause mtime to be updated on
 the file. In order to satisfy that requirement, we need to flush out
 any cached writes in nfs_getattr().
 Speed things up slightly by not committing the writes.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

include/linux/nfs_fs.h

@@ -62,6 +62,7 @@
 #define FLUSH_STABLE		4	/* commit to stable storage */
 #define FLUSH_LOWPRI		8	/* low priority background flush */
 #define FLUSH_HIGHPRI		16	/* high priority memory reclaim flush */
+#define FLUSH_NOCOMMIT		32	/* Don't send the NFSv3/v4 COMMIT */
 
 #ifdef __KERNEL__