Re: [PATCH v2 5/5] sunrpc: turn swapper_enable/disable functions into rpc_xprt_ops

[Trond Myklebust]

On Wed, Jun 3, 2015 at 10:43 AM, Jeff Layton <jlayton@xxxxxxxxxxxxxxx> wrote:
> RDMA xprts don't have a sock_xprt, but an rdma_xprt, so the
> xs_swapper_enable/disable functions will likely oops when fed an RDMA
> xprt. Turn these functions into rpc_xprt_ops so that that doesn't
> occur. For now the RDMA versions are no-ops.
>
> Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
> Signed-off-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
> ---
>  include/linux/sunrpc/xprt.h     | 16 ++++++++++++++--
>  net/sunrpc/clnt.c               |  4 ++--
>  net/sunrpc/xprtrdma/transport.c | 15 ++++++++++++++-
>  net/sunrpc/xprtsock.c           | 31 +++++++++++++++++++++++++------
>  4 files changed, 55 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
> index 26b1624128ec..7eb58610eb94 100644
> --- a/include/linux/sunrpc/xprt.h
> +++ b/include/linux/sunrpc/xprt.h
> @@ -133,6 +133,8 @@ struct rpc_xprt_ops {
>         void            (*close)(struct rpc_xprt *xprt);
>         void            (*destroy)(struct rpc_xprt *xprt);
>         void            (*print_stats)(struct rpc_xprt *xprt, struct seq_file *seq);
> +       int             (*enable_swap)(struct rpc_xprt *xprt);
> +       void            (*disable_swap)(struct rpc_xprt *xprt);
>  };
>
>  /*
> @@ -327,6 +329,18 @@ static inline __be32 *xprt_skip_transport_header(struct rpc_xprt *xprt, __be32 *
>         return p + xprt->tsh_size;
>  }
>
> +static inline int
> +xprt_enable_swap(struct rpc_xprt *xprt)
> +{
> +       return xprt->ops->enable_swap(xprt);
> +}
> +
> +static inline void
> +xprt_disable_swap(struct rpc_xprt *xprt)
> +{
> +       xprt->ops->disable_swap(xprt);
> +}
> +
>  /*
>   * Transport switch helper functions
>   */
> @@ -345,8 +359,6 @@ void                        xprt_release_rqst_cong(struct rpc_task *task);
>  void                   xprt_disconnect_done(struct rpc_xprt *xprt);
>  void                   xprt_force_disconnect(struct rpc_xprt *xprt);
>  void                   xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie);
> -int                    xs_swapper_enable(struct rpc_xprt *xprt);
> -void                   xs_swapper_disable(struct rpc_xprt *xprt);
>
>  bool                   xprt_lock_connect(struct rpc_xprt *, struct rpc_task *, void *);
>  void                   xprt_unlock_connect(struct rpc_xprt *, void *);
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index 804a75e71e84..60d1835edb26 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -2492,7 +2492,7 @@ retry:
>                         goto retry;
>                 }
>
> -               ret = xs_swapper_enable(xprt);
> +               ret = xprt_enable_swap(xprt);
>                 xprt_put(xprt);
>         }
>         return ret;
> @@ -2519,7 +2519,7 @@ retry:
>                         goto retry;
>                 }
>
> -               xs_swapper_disable(xprt);
> +               xprt_disable_swap(xprt);
>                 xprt_put(xprt);
>         }
>  }
> diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
> index 54f23b1be986..e7a157754095 100644
> --- a/net/sunrpc/xprtrdma/transport.c
> +++ b/net/sunrpc/xprtrdma/transport.c
> @@ -682,6 +682,17 @@ static void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
>            r_xprt->rx_stats.bad_reply_count);
>  }
>
> +static int
> +xprt_rdma_enable_swap(struct rpc_xprt *xprt)
> +{
> +       return 0;

Shouldn't the function be returning an error here? What does swapon
expect if the device you are trying to enable doesn't support swap?

> +}
> +
> +static void
> +xprt_rdma_disable_swap(struct rpc_xprt *xprt)
> +{
> +}
> +
>  /*
>   * Plumbing for rpc transport switch and kernel module
>   */
> @@ -700,7 +711,9 @@ static struct rpc_xprt_ops xprt_rdma_procs = {
>         .send_request           = xprt_rdma_send_request,
>         .close                  = xprt_rdma_close,
>         .destroy                = xprt_rdma_destroy,
> -       .print_stats            = xprt_rdma_print_stats
> +       .print_stats            = xprt_rdma_print_stats,
> +       .enable_swap            = xprt_rdma_enable_swap,
> +       .disable_swap           = xprt_rdma_disable_swap,
>  };
>
>  static struct xprt_class xprt_rdma = {
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index 16aa5dad41b2..b8aaf20aea96 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -1985,14 +1985,14 @@ static void xs_set_memalloc(struct rpc_xprt *xprt)
>  }
>
>  /**
> - * xs_swapper_enable - Tag this transport as being used for swap.
> + * xs_enable_swap - Tag this transport as being used for swap.
>   * @xprt: transport to tag
>   *
>   * Take a reference to this transport on behalf of the rpc_clnt, and
>   * optionally mark it for swapping if it wasn't already.
>   */
> -int
> -xs_swapper_enable(struct rpc_xprt *xprt)
> +static int
> +xs_enable_swap(struct rpc_xprt *xprt)
>  {
>         struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
>
> @@ -2007,14 +2007,14 @@ xs_swapper_enable(struct rpc_xprt *xprt)
>  }
>
>  /**
> - * xs_swapper_disable - Untag this transport as being used for swap.
> + * xs_disable_swap - Untag this transport as being used for swap.
>   * @xprt: transport to tag
>   *
>   * Drop a "swapper" reference to this xprt on behalf of the rpc_clnt. If the
>   * swapper refcount goes to 0, untag the socket as a memalloc socket.
>   */
> -void
> -xs_swapper_disable(struct rpc_xprt *xprt)
> +static void
> +xs_disable_swap(struct rpc_xprt *xprt)
>  {
>         struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt);
>
> @@ -2030,6 +2030,17 @@ xs_swapper_disable(struct rpc_xprt *xprt)
>  static void xs_set_memalloc(struct rpc_xprt *xprt)
>  {
>  }
> +
> +static int
> +xs_enable_swap(struct rpc_xprt *xprt)
> +{
> +       return 0;

Ditto.

> +}
> +
> +static void
> +xs_disable_swap(struct rpc_xprt *xprt)
> +{
> +}
>  #endif
>
>  static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
> @@ -2496,6 +2507,8 @@ static struct rpc_xprt_ops xs_local_ops = {
>         .close                  = xs_close,
>         .destroy                = xs_destroy,
>         .print_stats            = xs_local_print_stats,
> +       .enable_swap            = xs_enable_swap,
> +       .disable_swap           = xs_disable_swap,
>  };
>
>  static struct rpc_xprt_ops xs_udp_ops = {
> @@ -2515,6 +2528,8 @@ static struct rpc_xprt_ops xs_udp_ops = {
>         .close                  = xs_close,
>         .destroy                = xs_destroy,
>         .print_stats            = xs_udp_print_stats,
> +       .enable_swap            = xs_enable_swap,
> +       .disable_swap           = xs_disable_swap,
>  };
>
>  static struct rpc_xprt_ops xs_tcp_ops = {
> @@ -2531,6 +2546,8 @@ static struct rpc_xprt_ops xs_tcp_ops = {
>         .close                  = xs_tcp_shutdown,
>         .destroy                = xs_destroy,
>         .print_stats            = xs_tcp_print_stats,
> +       .enable_swap            = xs_enable_swap,
> +       .disable_swap           = xs_disable_swap,
>  };
>
>  /*
> @@ -2548,6 +2565,8 @@ static struct rpc_xprt_ops bc_tcp_ops = {
>         .close                  = bc_close,
>         .destroy                = bc_destroy,
>         .print_stats            = xs_tcp_print_stats,
> +       .enable_swap            = xs_enable_swap,
> +       .disable_swap           = xs_disable_swap,
>  };
>
>  static int xs_init_anyaddr(const int family, struct sockaddr *sap)
> --
> 2.4.2
>
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