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>
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@ -379,7 +379,7 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
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*/
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hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
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dlen = rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len
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- hdr;
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+ rqstp->rq_arg.tail[0].iov_len - hdr;
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/*
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* Round the length of the data which was specified up to
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* the next multiple of XDR units and then compare that
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@ -488,7 +488,7 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
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if (page_offset & 3) {
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u32 pad = 4 - (page_offset & 3);
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head->arg.page_len += pad;
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head->arg.tail[0].iov_len += pad;
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head->arg.len += pad;
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head->arg.buflen += pad;
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page_offset += pad;
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