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svcrdma: Preserve Receive buffer until svc_rdma_sendto 

Rather than releasing the incoming svc_rdma_recv_ctxt at the end of
svc_rdma_recvfrom, hold onto it until svc_rdma_sendto.

This permits the contents of the Receive buffer to be preserved
through svc_process and then referenced directly in sendto as it
constructs Write and Reply chunks to return to the client.

The real changes will come in subsequent patches.

Note: I cannot use ->xpo_release_rqst for this purpose because that
is called _before_ ->xpo_sendto. svc_rdma_sendto uses information in
the received Call transport header to construct the Reply transport
header, which is preserved in the RPC's Receive buffer.

The historical comment in svc_send() isn't helpful: it is already
obvious that ->xpo_release_rqst is being called before ->xpo_sendto,
but there is no explanation for this ordering going back to the
beginning of the git era.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Chuck Lever 2018-05-07 15:27:37 -04:00 committed by J. Bruce Fields
parent 1e5f416074
commit 3a88092ee3
2 changed files with 12 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
View File

@ -789,7 +789,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
goto out_readchunk;
complete:
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
rqstp->rq_xprt_ctxt = ctxt;
rqstp->rq_prot = IPPROTO_MAX;
svc_xprt_copy_addrs(rqstp, xprt);
return rqstp->rq_arg.len;

14
net/sunrpc/xprtrdma/svc_rdma_sendto.c
View File

@ -623,6 +623,7 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
struct svc_xprt *xprt = rqstp->rq_xprt;
struct svcxprt_rdma *rdma =
container_of(xprt, struct svcxprt_rdma, sc_xprt);
struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt;
__be32 *p, *rdma_argp, *rdma_resp, *wr_lst, *rp_ch;
struct xdr_buf *xdr = &rqstp->rq_res;
struct page *res_page;
@ -675,7 +676,12 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
wr_lst, rp_ch);
if (ret < 0)
goto err0;
return 0;
ret = 0;
out:
rqstp->rq_xprt_ctxt = NULL;
svc_rdma_recv_ctxt_put(rdma, rctxt);
return ret;
err2:
if (ret != -E2BIG && ret != -EINVAL)
@ -684,12 +690,14 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
ret = svc_rdma_send_error_msg(rdma, rdma_resp, rqstp);
if (ret < 0)
goto err0;
return 0;
ret = 0;
goto out;
err1:
put_page(res_page);
err0:
trace_svcrdma_send_failed(rqstp, ret);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
return -ENOTCONN;
ret = -ENOTCONN;
goto out;
}