[net/9p] Read side zerocopy changes for 9P2000.L protocol.
Venkateswararao Jujjuri (JV) [Sat, 29 Jan 2011 01:05:59 +0000 (17:05 -0800)]
Modify p9_client_read() 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>

net/9p/client.c
net/9p/protocol.c

index a848bca..82079f9 100644 (file)
@@ -1270,7 +1270,15 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
        if (count < rsize)
                rsize = count;
 
-       req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset, rsize);
+       /* 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_TREAD, "dqE", fid->fid, offset,
+                               rsize, data, udata);
+       } else {
+               req = p9_client_rpc(clnt, P9_TREAD, "dqd", fid->fid, offset,
+                               rsize);
+       }
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                goto error;
@@ -1284,13 +1292,15 @@ p9_client_read(struct p9_fid *fid, char *data, char __user *udata, u64 offset,
 
        P9_DPRINTK(P9_DEBUG_9P, "<<< RREAD count %d\n", count);
 
-       if (data) {
-               memmove(data, dataptr, count);
-       } else {
-               err = copy_to_user(udata, dataptr, count);
-               if (err) {
-                       err = -EFAULT;
-                       goto free_and_error;
+       if (!req->tc->pbuf_size) {
+               if (data) {
+                       memmove(data, dataptr, count);
+               } else {
+                       err = copy_to_user(udata, dataptr, count);
+                       if (err) {
+                               err = -EFAULT;
+                               goto free_and_error;
+                       }
                }
        }
        p9_free_req(clnt, req);
index 5936c50..7bca242 100644 (file)
@@ -114,6 +114,17 @@ pdu_write_u(struct p9_fcall *pdu, const char __user *udata, size_t size)
        return size - len;
 }
 
+static size_t
+pdu_write_urw(struct p9_fcall *pdu, const char *kdata, const char __user *udata,
+               size_t size)
+{
+       BUG_ON(pdu->size > P9_IOHDRSZ);
+       pdu->pubuf = (char __user *)udata;
+       pdu->pkbuf = (char *)kdata;
+       pdu->pbuf_size = size;
+       return 0;
+}
+
 /*
        b - int8_t
        w - int16_t
@@ -445,6 +456,16 @@ p9pdu_vwritef(struct p9_fcall *pdu, int proto_version, const char *fmt,
                                        errcode = -EFAULT;
                        }
                        break;
+               case 'E':{
+                                int32_t cnt = va_arg(ap, int32_t);
+                                const char *k = va_arg(ap, const void *);
+                                const char *u = va_arg(ap, const void *);
+                                errcode = p9pdu_writef(pdu, proto_version, "d",
+                                                cnt);
+                                if (!errcode && pdu_write_urw(pdu, k, u, cnt))
+                                       errcode = -EFAULT;
+                        }
+                        break;
                case 'U':{
                                int32_t count = va_arg(ap, int32_t);
                                const char __user *udata =