SUNRPC: ensure correct error is reported by xs_tcp_setup_socket()

[ Upstream commit 6ea44adce91526700535b3150f77f8639ae8c82d ]

If you attempt a TCP mount from an host that is unreachable in a way
that triggers an immediate error from kernel_connect(), that error
does not propagate up, instead EAGAIN is reported.

This results in call_connect_status receiving the wrong error.

A case that it easy to demonstrate is to attempt to mount from an
address that results in ENETUNREACH, but first deleting any default
route.
Without this patch, the mount.nfs process is persistently runnable
and is hard to kill.  With this patch it exits as it should.

The problem is caused by the fact that xs_tcp_force_close() eventually
calls
      xprt_wake_pending_tasks(xprt, -EAGAIN);
which causes an error return of -EAGAIN.  so when xs_tcp_setup_sock()
calls
      xprt_wake_pending_tasks(xprt, status);
the status is ignored.

Fixes: 4efdd92c9211 ("SUNRPC: Remove TCP client connection reset hack")
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 728d65fbab0ca8e3ee214de61eb24759f2652b3a..c9c0976d3bbbd230060ce5fd7821d7ae9bb8ccaf 100644 (file)
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -2363,7 +2363,12 @@ static void xs_tcp_setup_socket(struct work_struct *work)
        case -EHOSTUNREACH:
        case -EADDRINUSE:
        case -ENOBUFS:
-               /* retry with existing socket, after a delay */
+               /*
+                * xs_tcp_force_close() wakes tasks with -EIO.
+                * We need to wake them first to ensure the
+                * correct error code.
+                */
+               xprt_wake_pending_tasks(xprt, status);
                xs_tcp_force_close(xprt);
                goto out;
        }