On Thu, Jan 09, 2014 at 06:33:10PM +0800, Kinglong Mee wrote:
> Besides checking rpc_xprt out of xs_setup_bc_tcp,
> increase it's reference (it's important).
This sounds wrong to me: the presence of a backchannel can't prevent the
client's connection from going away. Instead, when the connection dies,
any associated backchannels should be immediately destroyed.
--b.
>
> Signed-off-by: Kinglong Mee <kinglongmee@xxxxxxxxx>
> ---
> fs/nfsd/nfs4callback.c | 19 ++++++++++++++++++-
> include/linux/sunrpc/xprt.h | 13 ++++++++++++-
> net/sunrpc/xprt.c | 12 ------------
> net/sunrpc/xprtsock.c | 9 ---------
> 4 files changed, 30 insertions(+), 23 deletions(-)
>
> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> index 7f05cd1..39c8ef8 100644
> --- a/fs/nfsd/nfs4callback.c
> +++ b/fs/nfsd/nfs4callback.c
> @@ -32,6 +32,7 @@
> */
>
> #include <linux/sunrpc/clnt.h>
> +#include <linux/sunrpc/xprt.h>
> #include <linux/sunrpc/svc_xprt.h>
> #include <linux/slab.h>
> #include "nfsd.h"
> @@ -635,6 +636,22 @@ static struct rpc_cred *get_backchannel_cred(struct nfs4_client *clp, struct rpc
> }
> }
>
> +static struct rpc_clnt *create_backchannel_client(struct rpc_create_args *args)
> +{
> + struct rpc_xprt *xprt;
> +
> + if (args->protocol != XPRT_TRANSPORT_BC_TCP)
> + return rpc_create(args);
> +
> + xprt = args->bc_xprt->xpt_bc_xprt;
> + if (xprt) {
> + xprt_get(xprt);
> + return rpc_create_xprt(args, xprt);
> + }
> +
> + return rpc_create(args);
> +}
> +
> static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *conn, struct nfsd4_session *ses)
> {
> struct rpc_timeout timeparms = {
> @@ -674,7 +691,7 @@ static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *c
> args.authflavor = ses->se_cb_sec.flavor;
> }
> /* Create RPC client */
> - client = rpc_create(&args);
> + client = create_backchannel_client(&args);
> if (IS_ERR(client)) {
> dprintk("NFSD: couldn't create callback client: %ld\n",
> PTR_ERR(client));
> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
> index 8097b9d..3e5efb2 100644
> --- a/include/linux/sunrpc/xprt.h
> +++ b/include/linux/sunrpc/xprt.h
> @@ -295,13 +295,24 @@ int xprt_adjust_timeout(struct rpc_rqst *req);
> void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
> void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);
> void xprt_release(struct rpc_task *task);
> -struct rpc_xprt * xprt_get(struct rpc_xprt *xprt);
> void xprt_put(struct rpc_xprt *xprt);
> struct rpc_xprt * xprt_alloc(struct net *net, size_t size,
> unsigned int num_prealloc,
> unsigned int max_req);
> void xprt_free(struct rpc_xprt *);
>
> +/**
> + * xprt_get - return a reference to an RPC transport.
> + * @xprt: pointer to the transport
> + *
> + */
> +static inline struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
> +{
> + if (atomic_inc_not_zero(&xprt->count))
> + return xprt;
> + return NULL;
> +}
> +
> static inline __be32 *xprt_skip_transport_header(struct rpc_xprt *xprt, __be32 *p)
> {
> return p + xprt->tsh_size;
> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
> index ddd198e..b0a1bbb 100644
> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -1383,15 +1383,3 @@ void xprt_put(struct rpc_xprt *xprt)
> if (atomic_dec_and_test(&xprt->count))
> xprt_destroy(xprt);
> }
> -
> -/**
> - * xprt_get - return a reference to an RPC transport.
> - * @xprt: pointer to the transport
> - *
> - */
> -struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
> -{
> - if (atomic_inc_not_zero(&xprt->count))
> - return xprt;
> - return NULL;
> -}
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index 7289e3c..37ea15a 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -2923,15 +2923,6 @@ static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
> struct svc_sock *bc_sock;
> struct rpc_xprt *ret;
>
> - if (args->bc_xprt->xpt_bc_xprt) {
> - /*
> - * This server connection already has a backchannel
> - * transport; we can't create a new one, as we wouldn't
> - * be able to match replies based on xid any more. So,
> - * reuse the already-existing one:
> - */
> - return args->bc_xprt->xpt_bc_xprt;
> - }
> xprt = xs_setup_xprt(args, xprt_tcp_slot_table_entries,
> xprt_tcp_slot_table_entries);
> if (IS_ERR(xprt))
> --
> 1.8.4.2
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