xprtrdma: Update only specific fields in private receive buffer
Now that rpcrdma_inline_fixup() updates only two fields in rq_rcv_buf, a full memcpy of that structure to rq_private_buf is unwarranted. Updating rq_private_buf fields only where needed also better documents what is going on. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Tested-by: Steve Wise <swise@opengridcomputing.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
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@ -750,6 +750,11 @@ rpcrdma_count_chunks(struct rpcrdma_rep *rep, int wrchunk, __be32 **iptrp)
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* The upper layer has set the maximum number of bytes it can
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* receive in each component of rq_rcv_buf. These values are set in
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* the head.iov_len, page_len, tail.iov_len, and buflen fields.
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*
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* Unlike the TCP equivalent (xdr_partial_copy_from_skb), in
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* many cases this function simply updates iov_base pointers in
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* rq_rcv_buf to point directly to the received reply data, to
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* avoid copying reply data.
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*/
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static void
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rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
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@ -763,6 +768,7 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
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* in the receive buffer, to avoid a memcopy.
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*/
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rqst->rq_rcv_buf.head[0].iov_base = srcp;
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rqst->rq_private_buf.head[0].iov_base = srcp;
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/* The contents of the receive buffer that follow
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* head.iov_len bytes are copied into the page list.
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@ -822,16 +828,15 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
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/* The tail iovec is redirected to the remaining data
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* in the receive buffer, to avoid a memcopy.
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*/
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if (copy_len || pad)
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if (copy_len || pad) {
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rqst->rq_rcv_buf.tail[0].iov_base = srcp;
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rqst->rq_private_buf.tail[0].iov_base = srcp;
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}
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if (copy_len)
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dprintk("RPC: %s: %d bytes in"
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" %d extra segments (%d lost)\n",
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__func__, olen, i, copy_len);
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/* TBD avoid a warning from call_decode() */
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rqst->rq_private_buf = rqst->rq_rcv_buf;
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}
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void
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