linux-kernel - [PATCH 7/8] nfsd: clean up and amend comments around nfsd4_cb_sequence

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Message-Id: <20250123-nfsd-6-14-v1-7-c1137a4fa2ae@kernel.org>
Date: Thu, 23 Jan 2025 15:25:24 -0500
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>, Neil Brown <neilb@...e.de>, 
 Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>, 
 Tom Talpey <tom@...pey.com>, "J. Bruce Fields" <bfields@...ldses.org>, 
 Kinglong Mee <kinglongmee@...il.com>, Trond Myklebust <trondmy@...nel.org>, 
 Anna Schumaker <anna@...nel.org>, "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
 netdev@...r.kernel.org, Jeff Layton <jlayton@...nel.org>
Subject: [PATCH 7/8] nfsd: clean up and amend comments around
 nfsd4_cb_sequence_done()

Add a new kerneldoc header, and clean up the comments a bit.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 fs/nfsd/nfs4callback.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 6e0561f3b21bd850b0387b5af7084eb05e818231..415fc8aae0f47c36f00b2384805c7a996fb1feb0 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1325,6 +1325,17 @@ static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
 	rpc_call_start(task);
 }
 
+/**
+ * nfsd4_cb_sequence_done - process the result of a CB_SEQUENCE
+ * @task: rpc_task
+ * @cb: nfsd4_callback for this call
+ *
+ * For minorversion 0, there is no CB_SEQUENCE. Only restart the call
+ * if the callback RPC client was killed. For v4.1+ the error handling
+ * is more sophisticated.
+ *
+ * Returns true if reply processing should continue.
+ */
 static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback *cb)
 {
 	struct nfs4_client *clp = cb->cb_clp;
@@ -1334,11 +1345,11 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
 	if (!clp->cl_minorversion) {
 		/*
 		 * If the backchannel connection was shut down while this
-		 * task was queued, we need to resubmit it after setting up
-		 * a new backchannel connection.
+		 * task was queued, resubmit it after setting up a new
+		 * backchannel connection.
 		 *
-		 * Note that if we lost our callback connection permanently
-		 * the submission code will error out, so we don't need to
+		 * Note that if the callback connection is permanently lost,
+		 * the submission code will error out. There is no need to
 		 * handle that case here.
 		 */
 		if (RPC_SIGNALLED(task))
@@ -1355,8 +1366,6 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
 	switch (cb->cb_seq_status) {
 	case 0:
 		/*
-		 * No need for lock, access serialized in nfsd4_cb_prepare
-		 *
 		 * RFC5661 20.9.3
 		 * If CB_SEQUENCE returns an error, then the state of the slot
 		 * (sequence ID, cached reply) MUST NOT change.
@@ -1365,6 +1374,11 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
 		ret = true;
 		break;
 	case -ESERVERFAULT:
+		/*
+		 * Client returned NFS4_OK, but decoding failed. Mark the
+		 * backchannel as faulty, but don't retransmit since the
+		 * call was successful.
+		 */
 		++session->se_cb_seq_nr[cb->cb_held_slot];
 		nfsd4_mark_cb_fault(cb->cb_clp);
 		break;

-- 
2.48.1