9p: Define and implement TLINK for 9P2000.L

This patch adds a helper function to get the dentry from inode and
uses it in creating a Hardlink

SYNOPSIS

size[4] Tlink tag[2] dfid[4] oldfid[4] newpath[s]

size[4] Rlink tag[2]

DESCRIPTION

Create a link 'newpath' in directory pointed by dfid linking to oldfid path.

[sripathik@in.ibm.com : p9_client_link should not free req structure
if p9_client_rpc has returned an error.]

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
index 7f64d72..5985c0f 100644
--- a/include/net/9p/9p.h
+++ b/include/net/9p/9p.h
@@ -139,6 +139,8 @@
 	P9_RSETATTR,
 	P9_TREADDIR = 40,
 	P9_RREADDIR,
+	P9_TLINK = 70,
+	P9_RLINK,
 	P9_TVERSION = 100,
 	P9_RVERSION,
 	P9_TAUTH = 102,