Hi Trond,
Have you tried nfsv3 mount with this patch?
Currently with this patch upstream kernel hangs.
On Mon, Feb 9, 2015 at 5:48 PM, Trond Myklebust
<trond.myklebust@xxxxxxxxxxxxxxx> wrote:
> The socket lock is currently held by the task that is requesting the
> connection be established. While that is efficient in the case where
> the connection happens quickly, it is racy in the case where it doesn't.
> What we really want is for the connect helper to be able to block access
> to the socket while it is being set up.
>
> This patch does so by arranging to transfer the socket lock from the
> task that is requesting the connect attempt, and then releasing that
> lock once everything is done.
> This scheme also gives us automatic protection against collisions with
> the RPC close code, so we can kill the cancel_delayed_work_sync()
> call in xs_close().
>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> include/linux/sunrpc/xprt.h | 3 +++
> net/sunrpc/xprt.c | 37 +++++++++++++++++++++++++++++++++----
> net/sunrpc/xprtsock.c | 7 +++++--
> 3 files changed, 41 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
> index 9d27ac45b909..2926e618dbc6 100644
> --- a/include/linux/sunrpc/xprt.h
> +++ b/include/linux/sunrpc/xprt.h
> @@ -347,6 +347,9 @@ void xprt_force_disconnect(struct rpc_xprt *xprt);
> void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie);
> int xs_swapper(struct rpc_xprt *xprt, int enable);
>
> +bool xprt_lock_connect(struct rpc_xprt *, struct rpc_task *, void *);
> +void xprt_unlock_connect(struct rpc_xprt *, void *);
> +
> /*
> * Reserved bit positions in xprt->state
> */
> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
> index ebbefad21a37..ff3574df8344 100644
> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -690,6 +690,37 @@ out_abort:
> spin_unlock(&xprt->transport_lock);
> }
>
> +bool xprt_lock_connect(struct rpc_xprt *xprt,
> + struct rpc_task *task,
> + void *cookie)
> +{
> + bool ret = false;
> +
> + spin_lock_bh(&xprt->transport_lock);
> + if (!test_bit(XPRT_LOCKED, &xprt->state))
> + goto out;
> + if (xprt->snd_task != task)
> + goto out;
> + xprt->snd_task = cookie;
> + ret = true;
> +out:
> + spin_unlock_bh(&xprt->transport_lock);
> + return ret;
> +}
> +
> +void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
> +{
> + spin_lock_bh(&xprt->transport_lock);
> + if (xprt->snd_task != cookie)
> + goto out;
> + if (!test_bit(XPRT_LOCKED, &xprt->state))
> + goto out;
> + xprt->snd_task =NULL;
> + xprt->ops->release_xprt(xprt, NULL);
> +out:
> + spin_unlock_bh(&xprt->transport_lock);
> +}
> +
> /**
> * xprt_connect - schedule a transport connect operation
> * @task: RPC task that is requesting the connect
> @@ -712,9 +743,7 @@ void xprt_connect(struct rpc_task *task)
> if (test_and_clear_bit(XPRT_CLOSE_WAIT, &xprt->state))
> xprt->ops->close(xprt);
>
> - if (xprt_connected(xprt))
> - xprt_release_write(xprt, task);
> - else {
> + if (!xprt_connected(xprt)) {
> task->tk_rqstp->rq_bytes_sent = 0;
> task->tk_timeout = task->tk_rqstp->rq_timeout;
> rpc_sleep_on(&xprt->pending, task, xprt_connect_status);
> @@ -726,6 +755,7 @@ void xprt_connect(struct rpc_task *task)
> xprt->stat.connect_start = jiffies;
> xprt->ops->connect(xprt, task);
> }
> + xprt_release_write(xprt, task);
> }
>
> static void xprt_connect_status(struct rpc_task *task)
> @@ -758,7 +788,6 @@ static void xprt_connect_status(struct rpc_task *task)
> dprintk("RPC: %5u xprt_connect_status: error %d connecting to "
> "server %s\n", task->tk_pid, -task->tk_status,
> xprt->servername);
> - xprt_release_write(xprt, task);
> task->tk_status = -EIO;
> }
> }
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index 0fa7ed93dc20..e57d8ed2c4d8 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -852,8 +852,6 @@ static void xs_close(struct rpc_xprt *xprt)
>
> dprintk("RPC: xs_close xprt %p\n", xprt);
>
> - cancel_delayed_work_sync(&transport->connect_worker);
> -
> xs_reset_transport(transport);
> xprt->reestablish_timeout = 0;
>
> @@ -2101,6 +2099,7 @@ static void xs_udp_setup_socket(struct work_struct *work)
> trace_rpc_socket_connect(xprt, sock, 0);
> status = 0;
> out:
> + xprt_unlock_connect(xprt, transport);
> xprt_clear_connecting(xprt);
> xprt_wake_pending_tasks(xprt, status);
> }
> @@ -2286,6 +2285,7 @@ static void xs_tcp_setup_socket(struct work_struct *work)
> case 0:
> case -EINPROGRESS:
> case -EALREADY:
> + xprt_unlock_connect(xprt, transport);
> xprt_clear_connecting(xprt);
> return;
> case -EINVAL:
> @@ -2303,6 +2303,7 @@ static void xs_tcp_setup_socket(struct work_struct *work)
> out_eagain:
> status = -EAGAIN;
> out:
> + xprt_unlock_connect(xprt, transport);
> xprt_clear_connecting(xprt);
> xprt_wake_pending_tasks(xprt, status);
> }
> @@ -2325,6 +2326,8 @@ static void xs_connect(struct rpc_xprt *xprt, struct rpc_task *task)
> {
> struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
>
> + WARN_ON_ONCE(!xprt_lock_connect(xprt, task, transport));
> +
> if (transport->sock != NULL && !RPC_IS_SOFTCONN(task)) {
> dprintk("RPC: xs_connect delayed xprt %p for %lu "
> "seconds\n",
> --
> 2.1.0
>
> --
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