[PATCH v3 3/4] SUNRPC: Server-side disconnect injection

[Chuck Lever <chuck.lever@oracle.com>]

Disconnect injection stress-tests the ability for both client and
server implementations to behave resiliently in the face of network
instability.

A file called /sys/kernel/debug/fail_sunrpc/ignore-server-disconnect
enables administrators to turn off server-side disconnect injection
while allowing other types of sunrpc errors to be injected. The
default setting is that server-side disconnect injection is enabled
(ignore=false).

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/debugfs.c |    3 +++
 net/sunrpc/fail.h    |    2 ++
 net/sunrpc/svc.c     |    8 ++++++++
 3 files changed, 13 insertions(+)

diff --git a/net/sunrpc/debugfs.c b/net/sunrpc/debugfs.c
index 04e453ad3508..827bf3a28178 100644
--- a/net/sunrpc/debugfs.c
+++ b/net/sunrpc/debugfs.c
@@ -259,6 +259,9 @@ static void fail_sunrpc_init(void)
 
 	debugfs_create_bool("ignore-client-disconnect", S_IFREG | 0600, dir,
 			    &fail_sunrpc.ignore_client_disconnect);
+
+	debugfs_create_bool("ignore-server-disconnect", S_IFREG | 0600, dir,
+			    &fail_sunrpc.ignore_server_disconnect);
 }
 #else
 static void fail_sunrpc_init(void)
diff --git a/net/sunrpc/fail.h b/net/sunrpc/fail.h
index 62c1b9fd59e2..69dc30cc44b8 100644
--- a/net/sunrpc/fail.h
+++ b/net/sunrpc/fail.h
@@ -14,6 +14,8 @@ struct fail_sunrpc_attr {
 	struct fault_attr	attr;
 
 	bool			ignore_client_disconnect;
+
+	bool			ignore_server_disconnect;
 };
 
 extern struct fail_sunrpc_attr fail_sunrpc;
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index 5aa263326b6a..bfcbaf7b3822 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -31,6 +31,8 @@
 
 #include <trace/events/sunrpc.h>
 
+#include "fail.h"
+
 #define RPCDBG_FACILITY	RPCDBG_SVCDSP
 
 static void svc_unregister(const struct svc_serv *serv, struct net *net);
@@ -1524,6 +1526,12 @@ svc_process(struct svc_rqst *rqstp)
 	struct svc_serv		*serv = rqstp->rq_server;
 	u32			dir;
 
+#if IS_ENABLED(CONFIG_FAIL_SUNRPC)
+	if (!fail_sunrpc.ignore_server_disconnect &&
+	    should_fail(&fail_sunrpc.attr, 1))
+		svc_xprt_deferred_close(rqstp->rq_xprt);
+#endif
+
 	/*
 	 * Setup response xdr_buf.
 	 * Initially it has just one page