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xprtrdma: Update only specific fields in private receive buffer

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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>
This commit is contained in:
Chuck Lever 2016-06-29 13:54:49 -04:00 committed by Anna Schumaker
parent cb0ae1fbb2
commit cfabe2c634
1 changed files with 9 additions and 4 deletions
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13
net/sunrpc/xprtrdma/rpc_rdma.c
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@ -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