[PATCH 5.10 61/66] SUNRPC: Ensure we flush any closed sockets before xs_xprt_free()

Greg Kroah-Hartman
2022-05-16T19:53:56Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

commit f00432063db1a0db484e85193eccc6845435b80e upstream.

We must ensure that all sockets are closed before we call xprt_free()
and release the reference to the net namespace. The problem is that
calling fput() will defer closing the socket until delayed_fput() gets
called.
Let's fix the situation by allowing rpciod and the transport teardown
code (which runs on the system wq) to call __fput_sync(), and directly
close the socket.

Reported-by: Felix Fu <foyjog@gmail.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: a73881c96d73 ("SUNRPC: Fix an Oops in udp_poll()")
Cc: stable@vger.kernel.org # 5.1.x: 3be232f11a3c: SUNRPC: Prevent immediate close+reconnect
Cc: stable@vger.kernel.org # 5.1.x: 89f42494f92f: SUNRPC: Don't call connect() more than once on a TCP socket
Cc: stable@vger.kernel.org # 5.1.x
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Meena Shanmugam <meenashanmugam@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/file_table.c | 1 +
include/trace/events/sunrpc.h | 1 -
net/sunrpc/xprt.c | 7 +------
net/sunrpc/xprtsock.c | 16 +++++++++++++---
4 files changed, 15 insertions(+), 10 deletions(-)

--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -376,6 +376,7 @@ void __fput_sync(struct file *file)
}

EXPORT_SYMBOL(fput);
+EXPORT_SYMBOL(__fput_sync);

void __init files_init(void)
{
--- a/include/trace/events/sunrpc.h
+++ b/include/trace/events/sunrpc.h
@@ -1006,7 +1006,6 @@ DEFINE_RPC_XPRT_LIFETIME_EVENT(connect);
DEFINE_RPC_XPRT_LIFETIME_EVENT(disconnect_auto);
DEFINE_RPC_XPRT_LIFETIME_EVENT(disconnect_done);
DEFINE_RPC_XPRT_LIFETIME_EVENT(disconnect_force);
-DEFINE_RPC_XPRT_LIFETIME_EVENT(disconnect_cleanup);
DEFINE_RPC_XPRT_LIFETIME_EVENT(destroy);

DECLARE_EVENT_CLASS(rpc_xprt_event,
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -886,12 +886,7 @@ void xprt_connect(struct rpc_task *task)
if (!xprt_lock_write(xprt, task))
return;

- if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
- trace_xprt_disconnect_cleanup(xprt);
- xprt->ops->close(xprt);
- }
-
- if (!xprt_connected(xprt)) {
+ if (!xprt_connected(xprt) && !test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
rpc_sleep_on_timeout(&xprt->pending, task, NULL,
xprt_request_timeout(task->tk_rqstp));
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -871,7 +871,7 @@ static int xs_local_send_request(struct

/* Close the stream if the previous transmission was incomplete */
if (xs_send_request_was_aborted(transport, req)) {
- xs_close(xprt);
+ xprt_force_disconnect(xprt);
return -ENOTCONN;
}

@@ -909,7 +909,7 @@ static int xs_local_send_request(struct
-status);
fallthrough;
case -EPIPE:
- xs_close(xprt);
+ xprt_force_disconnect(xprt);
status = -ENOTCONN;
}

@@ -1191,6 +1191,16 @@ static void xs_reset_transport(struct so

if (sk == NULL)
return;
+ /*
+ * Make sure we're calling this in a context from which it is safe
+ * to call __fput_sync(). In practice that means rpciod and the
+ * system workqueue.
+ */
+ if (!(current->flags & PF_WQ_WORKER)) {
+ WARN_ON_ONCE(1);
+ set_bit(XPRT_CLOSE_WAIT, &xprt->state);
+ return;
+ }

if (atomic_read(&transport->xprt.swapper))
sk_clear_memalloc(sk);
@@ -1214,7 +1224,7 @@ static void xs_reset_transport(struct so
mutex_unlock(&transport->recv_mutex);

trace_rpc_socket_close(xprt, sock);
- fput(filp);
+ __fput_sync(filp);

xprt_disconnect_done(xprt);
}