nfsd: fix callback restarts

Checking the rpc_client pointer is not a reliable way to detect
backchannel changes: cl_cb_client is changed only after shutting down
the rpc client, so the condition cl_cb_client = tk_client will always be
true.

Check the RPC_TASK_KILLED flag instead, and rewrite the code to avoid
the buggy cl_callbacks list and fix the lifetime rules due to double
calls of the ->prepare callback operations method for this retry case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 1 insertions, 3 deletions

diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index e791985..dbc4f85 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -63,13 +63,12 @@ typedef struct {
 
 struct nfsd4_callback {
 	struct nfs4_client *cb_clp;
-	struct list_head cb_per_client;
 	u32 cb_minorversion;
 	struct rpc_message cb_msg;
 	struct nfsd4_callback_ops *cb_ops;
 	struct work_struct cb_work;
 	int cb_status;
-	bool cb_done;
+	bool cb_need_restart;
 };
 
 struct nfsd4_callback_ops {
@@ -334,7 +333,6 @@ struct nfs4_client {
 	int			cl_cb_state;
 	struct nfsd4_callback	cl_cb_null;
 	struct nfsd4_session	*cl_cb_session;
-	struct list_head	cl_callbacks; /* list of in-progress callbacks */
 
 	/* for all client information that callback code might need: */
 	spinlock_t		cl_lock;