9P2010.L handshake: Add mount option

Add new mount V9FS mount option to specify protocol version

This patch adds a new mount option to specify protocol version.
With this option it is possible to use "-o version=" switch to
specify 9P protocol version to use. Valid options for version
are:
9p2000
9p2000.u
9p2010.L

Signed-off-by: Sripathi Kodi <sripathik@in.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
index 09d4f1e2e4a8..3b5f3c94a6eb 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -46,6 +46,7 @@ enum {
         Opt_msize,
         Opt_trans,
         Opt_legacy,
+        Opt_version,
         Opt_err,
 };
 
@@ -53,9 +54,30 @@ static const match_table_t tokens = {
         {Opt_msize, "msize=%u"},
         {Opt_legacy, "noextend"},
         {Opt_trans, "trans=%s"},
+        {Opt_version, "version=%s"},
         {Opt_err, NULL},
 };
 
+/* Interpret mount option for protocol version */
+static unsigned char get_protocol_version(const substring_t *name)
+{
+        unsigned char version = -EINVAL;
+        if (!strncmp("9p2000", name->from, name->to-name->from)) {
+                version = p9_proto_legacy;
+                P9_DPRINTK(P9_DEBUG_9P, "Protocol version: Legacy\n");
+        } else if (!strncmp("9p2000.u", name->from, name->to-name->from)) {
+                version = p9_proto_2000u;
+                P9_DPRINTK(P9_DEBUG_9P, "Protocol version: 9P2000.u\n");
+        } else if (!strncmp("9p2010.L", name->from, name->to-name->from)) {
+                version = p9_proto_2010L;
+                P9_DPRINTK(P9_DEBUG_9P, "Protocol version: 9P2010.L\n");
+        } else {
+                P9_DPRINTK(P9_DEBUG_ERROR, "Unknown protocol version %s. ",
+                                                        name->from);
+        }
+        return version;
+}
+
 static struct p9_req_t *
 p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...);
 
@@ -120,6 +142,12 @@ static int parse_opts(char *opts, struct p9_client *clnt)
                 case Opt_legacy:
                         clnt->dotu = 0;
                         break;
+                case Opt_version:
+                        ret = get_protocol_version(&args[0]);
+                        if (ret == -EINVAL)
+                                goto free_and_return;
+                        clnt->proto_version = ret;
+                        break;
                 default:
                         continue;
                 }