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From:   Jeff Layton <jlayton@kernel.org>
To:     chuck.lever@oracle.com
Cc:     linux-nfs@vger.kernel.org
Subject: [PATCH v2 1/2] nfsd: make nfsd4_run_cb a bool return function
Date:   Mon, 26 Sep 2022 14:41:01 -0400
Message-Id: <20220926184102.57254-1-jlayton@kernel.org>
MIME-Version: 1.0
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queue_work can return false and not queue anything, if the work is
already queued. If that happens in the case of a CB_RECALL, we'll have
taken an extra reference to the stid that will never be put. Ensure we
throw a warning in that case.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfsd/nfs4callback.c | 14 ++++++++++++--
 fs/nfsd/nfs4state.c    |  5 ++---
 fs/nfsd/state.h        |  2 +-
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 4ce328209f61..c4ee4a820a62 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1371,11 +1371,21 @@ void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
 	cb->cb_holds_slot = false;
 }
 
-void nfsd4_run_cb(struct nfsd4_callback *cb)
+/**
+ * nfsd4_run_cb - queue up a callback job to run
+ * @cb: callback to queue
+ *
+ * Kick off a callback to do its thing. Returns false if it was already
+ * on a queue, true otherwise.
+ */
+bool nfsd4_run_cb(struct nfsd4_callback *cb)
 {
+	bool queued;
 	struct nfs4_client *clp = cb->cb_clp;
 
 	nfsd41_cb_inflight_begin(clp);
-	if (!nfsd4_queue_cb(cb))
+	queued = nfsd4_queue_cb(cb);
+	if (!queued)
 		nfsd41_cb_inflight_end(clp);
+	return queued;
 }
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index e116f50afcf2..c78c3223161e 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4859,14 +4859,13 @@ static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
 	 * we know it's safe to take a reference.
 	 */
 	refcount_inc(&dp->dl_stid.sc_count);
-	nfsd4_run_cb(&dp->dl_recall);
+	WARN_ON_ONCE(!nfsd4_run_cb(&dp->dl_recall));
 }
 
 /* Called from break_lease() with flc_lock held. */
 static bool
 nfsd_break_deleg_cb(struct file_lock *fl)
 {
-	bool ret = false;
 	struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;
 	struct nfs4_file *fp = dp->dl_stid.sc_file;
 	struct nfs4_client *clp = dp->dl_stid.sc_client;
@@ -4892,7 +4891,7 @@ nfsd_break_deleg_cb(struct file_lock *fl)
 	fp->fi_had_conflict = true;
 	nfsd_break_one_deleg(dp);
 	spin_unlock(&fp->fi_lock);
-	return ret;
+	return false;
 }
 
 /**
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index b3477087a9fc..e2daef3cc003 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -692,7 +692,7 @@ extern void nfsd4_probe_callback_sync(struct nfs4_client *clp);
 extern void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *);
 extern void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
 		const struct nfsd4_callback_ops *ops, enum nfsd4_cb_op op);
-extern void nfsd4_run_cb(struct nfsd4_callback *cb);
+extern bool nfsd4_run_cb(struct nfsd4_callback *cb);
 extern int nfsd4_create_callback_queue(void);
 extern void nfsd4_destroy_callback_queue(void);
 extern void nfsd4_shutdown_callback(struct nfs4_client *);
-- 
2.37.3