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

Modify p9_client_readdir() to check the transport preference and act according
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>

2 files changed, 27 insertions, 2 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
index 412c52e1de74..6e07ef494ff2 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1735,7 +1735,14 @@ int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset)
         if (count < rsize)
                 rsize = count;
 
-        req = p9_client_rpc(clnt, P9_TREADDIR, "dqd", fid->fid, offset, rsize);
+        if ((clnt->trans_mod->pref & P9_TRANS_PREF_PAYLOAD_MASK) ==
+                        P9_TRANS_PREF_PAYLOAD_SEP) {
+                req = p9_client_rpc(clnt, P9_TREADDIR, "dqF", fid->fid,
+                                offset, rsize, data);
+        } else {
+                req = p9_client_rpc(clnt, P9_TREADDIR, "dqd", fid->fid,
+                                offset, rsize);
+        }
         if (IS_ERR(req)) {
                 err = PTR_ERR(req);
                 goto error;
@@ -1749,7 +1756,7 @@ int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset)
 
         P9_DPRINTK(P9_DEBUG_9P, "<<< RREADDIR count %d\n", count);
 
-        if (data)
+        if (!req->tc->pbuf_size && data)
                 memmove(data, dataptr, count);
 
         p9_free_req(clnt, req);
diff --git a/net/9p/protocol.c b/net/9p/protocol.c
index 7bca2421bfc8..2ce515b859b3 100644
--- a/net/9p/protocol.c
+++ b/net/9p/protocol.c
@@ -125,6 +125,15 @@ pdu_write_urw(struct p9_fcall *pdu, const char *kdata, const char __user *udata,
         return 0;
 }
 
+static size_t
+pdu_write_readdir(struct p9_fcall *pdu, const char *kdata, size_t size)
+{
+        BUG_ON(pdu->size > P9_READDIRHDRSZ);
+        pdu->pkbuf = (char *)kdata;
+        pdu->pbuf_size = size;
+        return 0;
+}
+
 /*
         b - int8_t
         w - int16_t
@@ -466,6 +475,15 @@ p9pdu_vwritef(struct p9_fcall *pdu, int proto_version, const char *fmt,
                                         errcode = -EFAULT;
                          }
                          break;
+                case 'F':{
+                                 int32_t cnt = va_arg(ap, int32_t);
+                                 const char *k = va_arg(ap, const void *);
+                                 errcode = p9pdu_writef(pdu, proto_version, "d",
+                                                 cnt);
+                                 if (!errcode && pdu_write_readdir(pdu, k, cnt))
+                                        errcode = -EFAULT;
+                         }
+                         break;
                 case 'U':{
                                 int32_t count = va_arg(ap, int32_t);
                                 const char __user *udata =