rpc: share one xps between all backchannels

The spec allows backchannels for multiple clients to share the same tcp
connection.  When that happens, we need to use the same xprt for all of
them.  Similarly, we need the same xps.

This fixes list corruption introduced by the multipath code.

Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: Trond Myklebust <trondmy@primarydata.com>

diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h
index b7dabc4baafd817d0b2a41c5cf8e54e4b3fddc47..79ba50856707b9b9a619be78335b27b383312ed9 100644 (file)
--- a/include/linux/sunrpc/svc_xprt.h
+++ b/include/linux/sunrpc/svc_xprt.h
@@ -84,6 +84,7 @@ struct svc_xprt {
 
        struct net              *xpt_net;
        struct rpc_xprt         *xpt_bc_xprt;   /* NFSv4.1 backchannel */
+       struct rpc_xprt_switch  *xpt_bc_xps;    /* NFSv4.1 backchannel */
 };
 
 static inline void unregister_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 5aa3834619a8c3222be6530f927ef30349e2fa74..5e3e1b63dbb3c97f0145bd15a23dba7d4e916528 100644 (file)
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -297,6 +297,7 @@ struct xprt_create {
        size_t                  addrlen;
        const char              *servername;
        struct svc_xprt         *bc_xprt;       /* NFSv4.1 backchannel */
+       struct rpc_xprt_switch  *bc_xps;
        unsigned int            flags;
 };
 

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index b33721d41adce8c8faefa1ce43915a3287744384..2808d550d2730ff8e36b6d8c072c65e1631064c4 100644 (file)
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -452,10 +452,20 @@ static struct rpc_clnt *rpc_create_xprt(struct rpc_create_args *args,
        struct rpc_clnt *clnt = NULL;
        struct rpc_xprt_switch *xps;
 
-       xps = xprt_switch_alloc(xprt, GFP_KERNEL);
-       if (xps == NULL) {
-               xprt_put(xprt);
-               return ERR_PTR(-ENOMEM);
+       if (args->bc_xprt && args->bc_xprt->xpt_bc_xps) {
+               WARN_ON(args->protocol != XPRT_TRANSPORT_BC_TCP);
+               xps = args->bc_xprt->xpt_bc_xps;
+               xprt_switch_get(xps);
+       } else {
+               xps = xprt_switch_alloc(xprt, GFP_KERNEL);
+               if (xps == NULL) {
+                       xprt_put(xprt);
+                       return ERR_PTR(-ENOMEM);
+               }
+               if (xprt->bc_xprt) {
+                       xprt_switch_get(xps);
+                       xprt->bc_xprt->xpt_bc_xps = xps;
+               }
        }
        clnt = rpc_new_client(args, xps, xprt, NULL);
        if (IS_ERR(clnt))

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index f5572e31d518f85b2afbbb9ec1b8e89d36448803..4f01f63102ee5d1ce936f54fa8feb3cedfc15607 100644 (file)
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -136,6 +136,8 @@ static void svc_xprt_free(struct kref *kref)
        /* See comment on corresponding get in xs_setup_bc_tcp(): */
        if (xprt->xpt_bc_xprt)
                xprt_put(xprt->xpt_bc_xprt);
+       if (xprt->xpt_bc_xps)
+               xprt_switch_put(xprt->xpt_bc_xps);
        xprt->xpt_ops->xpo_free(xprt);
        module_put(owner);
 }

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 2d3e0c42361e6190555eb3b0cd9465851c88fd7b..7e2b2fa189c340e7f0968aead6f878879e8a9a72 100644 (file)
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -3057,6 +3057,7 @@ static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args)
                return xprt;
 
        args->bc_xprt->xpt_bc_xprt = NULL;
+       args->bc_xprt->xpt_bc_xps = NULL;
        xprt_put(xprt);
        ret = ERR_PTR(-EINVAL);
 out_err: