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

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>

1 files changed, 21 insertions, 0 deletions

diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index 5936c50d0c93..7bca2421bfc8 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -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 =