svcrdma: Do not add XDR padding to xdr_buf page vector

An xdr_buf has a head, a vector of pages, and a tail. Each
RPC request is presented to the NFS server contained in an
xdr_buf.

The RDMA transport would like to supply the NFS server with only
the NFS WRITE payload bytes in the page vector. In some common
cases, that would allow the NFS server to swap those pages right
into the target file's page cache.

Have the transport's RDMA Read logic put XDR pad bytes in the tail
iovec, and not in the pages that hold the data payload.

The NFSv3 WRITE XDR decoder is finicky about the lengths involved,
so make sure it is looking in the correct places when computing
the total length of the incoming NFS WRITE request.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 2246454dec7654b3570f3c52bb5264567e32064c..c5eff5fde11caf30f2e62872e98a23f6c290c000 100644 (file)
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -379,7 +379,7 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
         */
        hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
        dlen = rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len
-               - hdr;
+               + rqstp->rq_arg.tail[0].iov_len - hdr;
        /*
         * Round the length of the data which was specified up to
         * the next multiple of XDR units and then compare that

diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index 3b24a646eb46725219011ffe859d998a0af06bb3..234be9de621011072f6c09135d0986a2940fb3f8 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -488,7 +488,7 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
        if (page_offset & 3) {
                u32 pad = 4 - (page_offset & 3);
 
-               head->arg.page_len += pad;
+               head->arg.tail[0].iov_len += pad;
                head->arg.len += pad;
                head->arg.buflen += pad;
                page_offset += pad;