9p: Include fsync support for 9p client

Implement the fsync in the client side by marking stat field values to 'don't touch' so that server may 
interpret it as a request to guarantee that the contents of the associated file are committed to stable 
storage before the Rwstat message is returned.

Without this patch, calling fsync on a 9p file results in "Invalid argument" error. Please check the attached 
C program.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> 
Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com> 
Acked-by: Venkateswararao Jujjuri (JV) <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>


diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 9d03d1e..a407fa3 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -176,7 +176,7 @@
  *
  */
 
-static void
+void
 v9fs_blank_wstat(struct p9_wstat *wstat)
 {
 	wstat->type = ~0;