SUNRPC: Handle zero length fragments correctly

A zero length fragment is really a bug, but let's ensure we don't
go nuts when one turns up.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index ec0bb153c140ed6dd2ad4a5085f732ff4dd4517b..492cec3f1451b31b4fdcbe6303b888463468379e 100644 (file)
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -405,8 +405,8 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr *msg, int flags,
        size_t want, seek_init = seek, offset = 0;
        ssize_t ret;
 
-       if (seek < buf->head[0].iov_len) {
-               want = min_t(size_t, count, buf->head[0].iov_len);
+       want = min_t(size_t, count, buf->head[0].iov_len);
+       if (seek < want) {
                ret = xs_read_kvec(sock, msg, flags, &buf->head[0], want, seek);
                if (ret <= 0)
                        goto sock_err;
@@ -417,8 +417,8 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr *msg, int flags,
                        goto out;
                seek = 0;
        } else {
-               seek -= buf->head[0].iov_len;
-               offset += buf->head[0].iov_len;
+               seek -= want;
+               offset += want;
        }
 
        want = xs_alloc_sparse_pages(buf,
@@ -443,8 +443,8 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr *msg, int flags,
                offset += want;
        }
 
-       if (seek < buf->tail[0].iov_len) {
-               want = min_t(size_t, count - offset, buf->tail[0].iov_len);
+       want = min_t(size_t, count - offset, buf->tail[0].iov_len);
+       if (seek < want) {
                ret = xs_read_kvec(sock, msg, flags, &buf->tail[0], want, seek);
                if (ret <= 0)
                        goto sock_err;
@@ -454,7 +454,7 @@ xs_read_xdr_buf(struct socket *sock, struct msghdr *msg, int flags,
                if (ret != want)
                        goto out;
        } else
-               offset += buf->tail[0].iov_len;
+               offset = seek_init;
        ret = -EMSGSIZE;
 out:
        *read = offset - seek_init;
@@ -482,6 +482,14 @@ xs_read_stream_request_done(struct sock_xprt *transport)
        return transport->recv.fraghdr & cpu_to_be32(RPC_LAST_STREAM_FRAGMENT);
 }
 
+static void
+xs_read_stream_check_eor(struct sock_xprt *transport,
+               struct msghdr *msg)
+{
+       if (xs_read_stream_request_done(transport))
+               msg->msg_flags |= MSG_EOR;
+}
+
 static ssize_t
 xs_read_stream_request(struct sock_xprt *transport, struct msghdr *msg,
                int flags, struct rpc_rqst *req)
@@ -493,17 +501,24 @@ xs_read_stream_request(struct sock_xprt *transport, struct msghdr *msg,
        xs_read_header(transport, buf);
 
        want = transport->recv.len - transport->recv.offset;
-       ret = xs_read_xdr_buf(transport->sock, msg, flags, buf,
-                       transport->recv.copied + want, transport->recv.copied,
-                       &read);
-       transport->recv.offset += read;
-       transport->recv.copied += read;
+       if (want != 0) {
+               ret = xs_read_xdr_buf(transport->sock, msg, flags, buf,
+                               transport->recv.copied + want,
+                               transport->recv.copied,
+                               &read);
+               transport->recv.offset += read;
+               transport->recv.copied += read;
+       } else
+               read = 0;
+
        if (transport->recv.offset == transport->recv.len) {
-               if (xs_read_stream_request_done(transport))
-                       msg->msg_flags |= MSG_EOR;
+               xs_read_stream_check_eor(transport, msg);
                return read;
        }
 
+       if (want == 0)
+               return 0;
+
        switch (ret) {
        default:
                break;