[Devel] [PATCH v2 2/3] sunrpc: bring back SUNRPC task abort logic

[Stanislav Kinsburskiy]

We had this logic in vz6. But it was applied to any stop there.
The intention was to solve 2 tasks:
1) allow to stop container when network is unaccessible
2) allow to suspend container with blocked network traffic.

In vz7 we need the traffic to flow on suspend. Thus we have to distinguish
between suspend (where the network must work) and "fast stop", when we
want to kill container quickly (something similar to "reset" button).
This dinstiguishment can be based on per-net SUNRPC "kill-tasks" attribute,
which has to be set only in case of "fast stop".

This solution allows us to mimic hardware behaviour closely. IOW, on normal
stop (or migration) SUNRPC operates normally. But when user wants to stop it
fast (i.e. he doesn't care about data, etc), then he can use "--fast" option
and this patch comes into play.

https://jira.sw.ru/browse/PSBM-66510

Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
---
 include/linux/sunrpc/clnt.h |    2 ++
 net/sunrpc/clnt.c           |   14 ++++++++++++++
 net/sunrpc/sched.c          |    5 +++++
 3 files changed, 21 insertions(+)

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index 597e5ae..75677554 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -186,5 +186,7 @@ const char *rpc_proc_name(const struct rpc_task *task);
 int rpc_task_kill_proc_init(struct net *net);
 void rpc_task_kill_proc_fini(struct net *net);
 
+bool rpc_abort_task(struct rpc_task *task);
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_SUNRPC_CLNT_H */
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index e64f751..2635c49 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -2607,3 +2607,17 @@ void rpc_task_kill_proc_fini(struct net *net)
 	if (sn->kill_tasks_proc)
 		remove_proc_entry("kill-tasks", sn->proc_net_rpc);
 }
+
+bool rpc_abort_task(struct rpc_task *task)
+{
+	struct net *net = rpc_net_ns(task->tk_client);
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+	if (!sn->kill_tasks)
+		return false;
+
+	dprintk("RPC: SUNRPC traffic is suppressed. Drop task %5u with EIO.\n",
+			task->tk_pid);
+
+	return true;
+}
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 16ada61..cd41946 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -728,6 +728,11 @@ static void __rpc_execute(struct rpc_task *task)
 	if (RPC_IS_QUEUED(task))
 		return;
 
+	if (rpc_abort_task(task)) {
+		task->tk_flags |= RPC_TASK_KILLED;
+		rpc_exit(task, -EIO);
+	}
+
 	for (;;) {
 		void (*do_action)(struct rpc_task *);