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svcrdma: Copy construction of svc_rqst::rq_arg to rdma_read_complete()

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Once a set of RDMA Reads are complete, the Read completion handler
will poke the transport to trigger a second call to
svc_rdma_recvfrom(). recvfrom() will then merge the RDMA Read
payloads with the previously received RPC header to form a completed
RPC Call message.

The new code is copied from the svc_rdma_process_read_list() path.
A subsequent patch will make use of this code and remove the code
that this was copied from (svc_rdma_rw.c).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2023-12-18 17:32:01 -05:00
parent a937693a82
commit ecba85e951
2 changed files with 93 additions and 1 deletions
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1
include/trace/events/rpcrdma.h
View File

@ -2112,6 +2112,7 @@ TRACE_EVENT(svcrdma_wc_read,
DEFINE_SEND_FLUSH_EVENT(svcrdma_wc_read_flush);
DEFINE_SEND_FLUSH_EVENT(svcrdma_wc_read_err);
DEFINE_SIMPLE_CID_EVENT(svcrdma_read_finished);
DEFINE_SIMPLE_CID_EVENT(svcrdma_wc_write);
DEFINE_SEND_FLUSH_EVENT(svcrdma_wc_write_flush);

93
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
View File

@ -767,10 +767,86 @@ static bool svc_rdma_is_reverse_direction_reply(struct svc_xprt *xprt,
return true;
}
/* Finish constructing the RPC Call message in rqstp::rq_arg.
*
* The incoming RPC/RDMA message is an RDMA_MSG type message
* with a single Read chunk (only the upper layer data payload
* was conveyed via RDMA Read).
*/
static void svc_rdma_read_complete_one(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *ctxt)
{
struct svc_rdma_chunk *chunk = pcl_first_chunk(&ctxt->rc_read_pcl);
struct xdr_buf *buf = &rqstp->rq_arg;
unsigned int length;
/* Split the Receive buffer between the head and tail
* buffers at Read chunk's position. XDR roundup of the
* chunk is not included in either the pagelist or in
* the tail.
*/
buf->tail[0].iov_base = buf->head[0].iov_base + chunk->ch_position;
buf->tail[0].iov_len = buf->head[0].iov_len - chunk->ch_position;
buf->head[0].iov_len = chunk->ch_position;
/* Read chunk may need XDR roundup (see RFC 8166, s. 3.4.5.2).
*
* If the client already rounded up the chunk length, the
* length does not change. Otherwise, the length of the page
* list is increased to include XDR round-up.
*
* Currently these chunks always start at page offset 0,
* thus the rounded-up length never crosses a page boundary.
*/
buf->pages = &rqstp->rq_pages[0];
length = xdr_align_size(chunk->ch_length);
buf->page_len = length;
buf->len += length;
buf->buflen += length;
}
/* Finish constructing the RPC Call message in rqstp::rq_arg.
*
* The incoming RPC/RDMA message is an RDMA_MSG type message
* with payload in multiple Read chunks and no PZRC.
*/
static void svc_rdma_read_complete_multiple(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *ctxt)
{
struct xdr_buf *buf = &rqstp->rq_arg;
buf->len += ctxt->rc_readbytes;
buf->buflen += ctxt->rc_readbytes;
buf->head[0].iov_base = page_address(rqstp->rq_pages[0]);
buf->head[0].iov_len = min_t(size_t, PAGE_SIZE, ctxt->rc_readbytes);
buf->pages = &rqstp->rq_pages[1];
buf->page_len = ctxt->rc_readbytes - buf->head[0].iov_len;
}
/* Finish constructing the RPC Call message in rqstp::rq_arg.
*
* The incoming RPC/RDMA message is an RDMA_NOMSG type message
* (the RPC message body was conveyed via RDMA Read).
*/
static void svc_rdma_read_complete_pzrc(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *ctxt)
{
struct xdr_buf *buf = &rqstp->rq_arg;
buf->len += ctxt->rc_readbytes;
buf->buflen += ctxt->rc_readbytes;
buf->head[0].iov_base = page_address(rqstp->rq_pages[0]);
buf->head[0].iov_len = min_t(size_t, PAGE_SIZE, ctxt->rc_readbytes);
buf->pages = &rqstp->rq_pages[1];
buf->page_len = ctxt->rc_readbytes - buf->head[0].iov_len;
}
static noinline void svc_rdma_read_complete(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *ctxt)
{
int i;
unsigned int i;
/* Transfer the Read chunk pages into @rqstp.rq_pages, replacing
* the rq_pages that were already allocated for this rqstp.
@ -789,6 +865,21 @@ static noinline void svc_rdma_read_complete(struct svc_rqst *rqstp,
* pages in ctxt::rc_pages a second time.
*/
ctxt->rc_page_count = 0;
/* Finish constructing the RPC Call message. The exact
* procedure for that depends on what kind of RPC/RDMA
* chunks were provided by the client.
*/
if (pcl_is_empty(&ctxt->rc_call_pcl)) {
if (ctxt->rc_read_pcl.cl_count == 1)
svc_rdma_read_complete_one(rqstp, ctxt);
else
svc_rdma_read_complete_multiple(rqstp, ctxt);
} else {
svc_rdma_read_complete_pzrc(rqstp, ctxt);
}
trace_svcrdma_read_finished(&ctxt->rc_cid);
}
/**