[net/9p] Write side zerocopy changes for 9P2000.L protocol.

Modify p9_client_write() to check the transport preference and act accordingly.
If the preference is P9_TRANS_PREF_PAYLOAD_SEP, send the payload
separately instead of putting it directly on PDU.

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

diff --git a/net/9p/client.c b/net/9p/client.c
index 82079f9..412c52e 100644 (file)
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1333,12 +1333,21 @@ p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
 
        if (count < rsize)
                rsize = count;
-       if (data)
-               req = p9_client_rpc(clnt, P9_TWRITE, "dqD", fid->fid, offset,
-                                                               rsize, data);
-       else
-               req = p9_client_rpc(clnt, P9_TWRITE, "dqU", fid->fid, offset,
-                                                               rsize, udata);
+
+       /* Don't bother zerocopy form small IO (< 1024) */
+       if (((clnt->trans_mod->pref & P9_TRANS_PREF_PAYLOAD_MASK) ==
+                               P9_TRANS_PREF_PAYLOAD_SEP) && (rsize > 1024)) {
+               req = p9_client_rpc(clnt, P9_TWRITE, "dqE", fid->fid, offset,
+                               rsize, data, udata);
+       } else {
+
+               if (data)
+                       req = p9_client_rpc(clnt, P9_TWRITE, "dqD", fid->fid,
+                                       offset, rsize, data);
+               else
+                       req = p9_client_rpc(clnt, P9_TWRITE, "dqU", fid->fid,
+                                       offset, rsize, udata);
+       }
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                goto error;