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Subject: [PATCH RFC 3/4] SUNRPC: Use a per-transport receive bio_vec array
From:   Chuck Lever <cel@kernel.org>
To:     linux-nfs@vger.kernel.org
Cc:     Chuck Lever <chuck.lever@oracle.com>, dhowells@redhat.com
Date:   Sun, 09 Jul 2023 16:05:11 -0400
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From: Chuck Lever <chuck.lever@oracle.com>

TCP receives are serialized, so we need only one bio_vec array per
socket. This shrinks the size of struct svc_rqst by 4144 bytes on
x86_64.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 include/linux/sunrpc/svc.h     |    1 -
 include/linux/sunrpc/svcsock.h |    2 ++
 net/sunrpc/svcsock.c           |    2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index f8751118c122..36052188222d 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -224,7 +224,6 @@ struct svc_rqst {
 
 	struct folio_batch	rq_fbatch;
 	struct kvec		rq_vec[RPCSVC_MAXPAGES]; /* generally useful.. */
-	struct bio_vec		rq_bvec[RPCSVC_MAXPAGES];
 
 	__be32			rq_xid;		/* transmission id */
 	u32			rq_prog;	/* program number */
diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
index a9bfeadf4cbe..4efae760f3cb 100644
--- a/include/linux/sunrpc/svcsock.h
+++ b/include/linux/sunrpc/svcsock.h
@@ -40,6 +40,8 @@ struct svc_sock {
 
 	struct completion	sk_handshake_done;
 
+	struct bio_vec		sk_recv_bvec[RPCSVC_MAXPAGES]
+						____cacheline_aligned;
 	struct bio_vec		sk_send_bvec[RPCSVC_MAXPAGES]
 						____cacheline_aligned;
 
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index ae7143f68343..6f672cb0b0b3 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -333,7 +333,7 @@ static ssize_t svc_tcp_read_msg(struct svc_rqst *rqstp, size_t buflen,
 {
 	struct svc_sock *svsk =
 		container_of(rqstp->rq_xprt, struct svc_sock, sk_xprt);
-	struct bio_vec *bvec = rqstp->rq_bvec;
+	struct bio_vec *bvec = svsk->sk_recv_bvec;
 	struct msghdr msg = { NULL };
 	unsigned int i;
 	ssize_t len;