[PATCH 2 02/14] NFSD: Convert the callback workqueue to use delayed_work

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

Normally, NFSv4 callback operations are supposed to be sent to the
client as soon as they are queued up.

In a moment, I will introduce a recovery path where the server has
to wait for the client to reconnect. We don't want a hard busy wait
here -- the callback should be requeued to try again in several
milliseconds.

For now, convert nfsd4_callback from struct work_struct to struct
delayed_work, and queue with a zero delay argument. This should
avoid behavior changes for current operation.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs4callback.c |    6 +++---
 fs/nfsd/state.h        |    2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 43b0a34a5d5b..1ed2512b3648 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -887,7 +887,7 @@ static struct workqueue_struct *callback_wq;
 
 static bool nfsd4_queue_cb(struct nfsd4_callback *cb)
 {
-	return queue_work(callback_wq, &cb->cb_work);
+	return queue_delayed_work(callback_wq, &cb->cb_work, 0);
 }
 
 static void nfsd41_cb_inflight_begin(struct nfs4_client *clp)
@@ -1370,7 +1370,7 @@ static void
 nfsd4_run_cb_work(struct work_struct *work)
 {
 	struct nfsd4_callback *cb =
-		container_of(work, struct nfsd4_callback, cb_work);
+		container_of(work, struct nfsd4_callback, cb_work.work);
 	struct nfs4_client *clp = cb->cb_clp;
 	struct rpc_clnt *clnt;
 	int flags;
@@ -1415,7 +1415,7 @@ void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
 	cb->cb_msg.rpc_argp = cb;
 	cb->cb_msg.rpc_resp = cb;
 	cb->cb_ops = ops;
-	INIT_WORK(&cb->cb_work, nfsd4_run_cb_work);
+	INIT_DELAYED_WORK(&cb->cb_work, nfsd4_run_cb_work);
 	cb->cb_seq_status = 1;
 	cb->cb_status = 0;
 	cb->cb_need_restart = false;
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 41bdc913fa71..87c4372ba36a 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -68,7 +68,7 @@ struct nfsd4_callback {
 	struct nfs4_client *cb_clp;
 	struct rpc_message cb_msg;
 	const struct nfsd4_callback_ops *cb_ops;
-	struct work_struct cb_work;
+	struct delayed_work cb_work;
 	int cb_seq_status;
 	int cb_status;
 	bool cb_need_restart;