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@xxxxxxxxxx>
---
net/sunrpc/xprtrdma/rpc_rdma.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index d018eb7..a0e811d 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -750,6 +750,11 @@ rpcrdma_count_chunks(struct rpcrdma_rep *rep, int wrchunk, __be32 **iptrp)
* The upper layer has set the maximum number of bytes it can
* receive in each component of rq_rcv_buf. These values are set in
* the head.iov_len, page_len, tail.iov_len, and buflen fields.
+ *
+ * Unlike the TCP equivalent (xdr_partial_copy_from_skb), in
+ * many cases this function simply updates iov_base pointers in
+ * rq_rcv_buf to point directly to the received reply data, to
+ * avoid copying reply data.
*/
static void
rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
@@ -763,6 +768,7 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
* in the receive buffer, to avoid a memcopy.
*/
rqst->rq_rcv_buf.head[0].iov_base = srcp;
+ rqst->rq_private_buf.head[0].iov_base = srcp;
/* The contents of the receive buffer that follow
* head.iov_len bytes are copied into the page list.
@@ -822,16 +828,15 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
/* The tail iovec is redirected to the remaining data
* in the receive buffer, to avoid a memcopy.
*/
- if (copy_len || pad)
+ if (copy_len || pad) {
rqst->rq_rcv_buf.tail[0].iov_base = srcp;
+ rqst->rq_private_buf.tail[0].iov_base = srcp;
+ }
if (copy_len)
dprintk("RPC: %s: %d bytes in"
" %d extra segments (%d lost)\n",
__func__, olen, i, copy_len);
-
- /* TBD avoid a warning from call_decode() */
- rqst->rq_private_buf = rqst->rq_rcv_buf;
}
void
--
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