From cba5f62b1830c1919b47544789bc993e6e617dc6 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Thu, 30 Apr 2015 11:49:24 +0200
Subject: [PATCH] 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>
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