linux-kernel - [PATCH RFC 1/2] sunrpc: delay pc_release callback until after sending a reply

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Message-Id: <20250703-nfsd-testing-v1-1-cece54f36556@kernel.org>
Date: Thu, 03 Jul 2025 15:53:12 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Trond Myklebust <trondmy@...nel.org>, Anna Schumaker <anna@...nel.org>, 
 Chuck Lever <chuck.lever@...cle.com>, NeilBrown <neil@...wn.name>, 
 Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>, 
 Tom Talpey <tom@...pey.com>, Mike Snitzer <snitzer@...nel.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Jeff Layton <jlayton@...nel.org>
Subject: [PATCH RFC 1/2] sunrpc: delay pc_release callback until after
 sending a reply

The server-side sunrpc code currently calls pc_release before sending
the reply. A later nfsd patch will change some pc_release callbacks to
do extra work to clean the pagecache. There is no need to delay sending
the reply for this, however.

Change svc_process and svc_process_bc to call pc_release after sending
the reply instead of before.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 net/sunrpc/svc.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index b1fab3a6954437cf751e4725fa52cfc83eddf2ab..103bb6ba8e140fdccd6cab124e715caeb41bb445 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -1426,8 +1426,6 @@ svc_process_common(struct svc_rqst *rqstp)
 
 	/* Call the function that processes the request. */
 	rc = process.dispatch(rqstp);
-	if (procp->pc_release)
-		procp->pc_release(rqstp);
 	xdr_finish_decode(xdr);
 
 	if (!rc)
@@ -1526,6 +1524,14 @@ static void svc_drop(struct svc_rqst *rqstp)
 	trace_svc_drop(rqstp);
 }
 
+static void svc_release_rqst(struct svc_rqst *rqstp)
+{
+	const struct svc_procedure *procp = rqstp->rq_procinfo;
+
+	if (procp && procp->pc_release)
+		procp->pc_release(rqstp);
+}
+
 /**
  * svc_process - Execute one RPC transaction
  * @rqstp: RPC transaction context
@@ -1533,7 +1539,7 @@ static void svc_drop(struct svc_rqst *rqstp)
  */
 void svc_process(struct svc_rqst *rqstp)
 {
-	struct kvec		*resv = &rqstp->rq_res.head[0];
+	struct kvec			*resv = &rqstp->rq_res.head[0];
 	__be32 *p;
 
 #if IS_ENABLED(CONFIG_FAIL_SUNRPC)
@@ -1565,9 +1571,12 @@ void svc_process(struct svc_rqst *rqstp)
 	if (unlikely(*p != rpc_call))
 		goto out_baddir;
 
-	if (!svc_process_common(rqstp))
+	if (!svc_process_common(rqstp)) {
+		svc_release_rqst(rqstp);
 		goto out_drop;
+	}
 	svc_send(rqstp);
+	svc_release_rqst(rqstp);
 	return;
 
 out_baddir:
@@ -1635,6 +1644,7 @@ void svc_process_bc(struct rpc_rqst *req, struct svc_rqst *rqstp)
 	if (!proc_error) {
 		/* Processing error: drop the request */
 		xprt_free_bc_request(req);
+		svc_release_rqst(rqstp);
 		return;
 	}
 	/* Finally, send the reply synchronously */
@@ -1648,6 +1658,7 @@ void svc_process_bc(struct rpc_rqst *req, struct svc_rqst *rqstp)
 	timeout.to_maxval = timeout.to_initval;
 	memcpy(&req->rq_snd_buf, &rqstp->rq_res, sizeof(req->rq_snd_buf));
 	task = rpc_run_bc_task(req, &timeout);
+	svc_release_rqst(rqstp);
 
 	if (IS_ERR(task))
 		return;

-- 
2.50.0