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

Create a symbolic link

SYNOPSIS

size[4] Tsymlink tag[2] fid[4] name[s] symtgt[s] gid[4]

size[4] Rsymlink tag[2] qid[13]

DESCRIPTION

Create a symbolic link named 'name' pointing to 'symtgt'.
gid represents the effective group id of the caller.
The  permissions of a symbolic link are irrelevant hence it is omitted
from the protocol.

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Reviewed-by: Sripathi Kodi <sripathik@in.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

include/net/9p/9p.h

@@ -88,6 +88,8 @@ do { \
  * enum p9_msg_t - 9P message types
  * @P9_TSTATFS: file system status request
  * @P9_RSTATFS: file system status response
+ * @P9_TSYMLINK: make symlink request
+ * @P9_RSYMLINK: make symlink response
  * @P9_TRENAME: rename request
  * @P9_RRENAME: rename response
  * @P9_TVERSION: version handshake request
@@ -131,6 +133,8 @@ do { \
 enum p9_msg_t {
 	P9_TSTATFS = 8,
 	P9_RSTATFS,
+	P9_TSYMLINK = 16,
+	P9_RSYMLINK,
 	P9_TRENAME = 20,
 	P9_RRENAME,
 	P9_TGETATTR = 24,