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sunrpc: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage 

When transmitting data, call down into TCP using sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced rather than
performing sendpage calls to transmit header, data pages and trailer.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
cc: Trond Myklebust <trond.myklebust@hammerspace.com>
cc: Anna Schumaker <anna@kernel.org>
cc: Jeff Layton <jlayton@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
David Howells 2023-06-09 11:02:18 +01:00 committed by Jakub Kicinski
parent 345ee3e812
commit 5df5dd03a8
2 changed files with 17 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
include/linux/sunrpc/svc.h
View File

@ -161,16 +161,15 @@ static inline bool svc_put_not_last(struct svc_serv *serv)
extern u32 svc_max_payload(const struct svc_rqst *rqstp);
/*
* RPC Requsts and replies are stored in one or more pages.
* RPC Requests and replies are stored in one or more pages.
* We maintain an array of pages for each server thread.
* Requests are copied into these pages as they arrive. Remaining
* pages are available to write the reply into.
*
* Pages are sent using ->sendpage so each server thread needs to
* allocate more to replace those used in sending. To help keep track
* of these pages we have a receive list where all pages initialy live,
* and a send list where pages are moved to when there are to be part
* of a reply.
* Pages are sent using ->sendmsg with MSG_SPLICE_PAGES so each server thread
* needs to allocate more to replace those used in sending. To help keep track
* of these pages we have a receive list where all pages initialy live, and a
* send list where pages are moved to when there are to be part of a reply.
*
* We use xdr_buf for holding responses as it fits well with NFS
* read responses (that have a header, and some data pages, and possibly

38
net/sunrpc/svcsock.c
View File

@ -1203,13 +1203,14 @@ err_noclose:
static int svc_tcp_send_kvec(struct socket *sock, const struct kvec *vec,
int flags)
{
return kernel_sendpage(sock, virt_to_page(vec->iov_base),
offset_in_page(vec->iov_base),
vec->iov_len, flags);
struct msghdr msg = { .msg_flags = MSG_SPLICE_PAGES | flags, };
iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 1, vec->iov_len);
return sock_sendmsg(sock, &msg);
}
/*
* kernel_sendpage() is used exclusively to reduce the number of
* MSG_SPLICE_PAGES is used exclusively to reduce the number of
* copy operations in this path. Therefore the caller must ensure
* that the pages backing @xdr are unchanging.
*
@ -1249,28 +1250,13 @@ static int svc_tcp_sendmsg(struct socket *sock, struct xdr_buf *xdr,
if (ret != head->iov_len)
goto out;
if (xdr->page_len) {
unsigned int offset, len, remaining;
struct bio_vec *bvec;
bvec = xdr->bvec + (xdr->page_base >> PAGE_SHIFT);
offset = offset_in_page(xdr->page_base);
remaining = xdr->page_len;
while (remaining > 0) {
len = min(remaining, bvec->bv_len - offset);
ret = kernel_sendpage(sock, bvec->bv_page,
bvec->bv_offset + offset,
len, 0);
if (ret < 0)
return ret;
*sentp += ret;
if (ret != len)
goto out;
remaining -= len;
offset = 0;
bvec++;
}
}
msg.msg_flags = MSG_SPLICE_PAGES;
iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, xdr->bvec,
xdr_buf_pagecount(xdr), xdr->page_len);
ret = sock_sendmsg(sock, &msg);
if (ret < 0)
return ret;
*sentp += ret;
if (tail->iov_len) {
ret = svc_tcp_send_kvec(sock, tail, 0);