From 99de8ea962bbc11a51ad4c52e3dc93bee5f6ba70 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Wed, 8 Dec 2010 12:45:44 -0500 Subject: rpc: keep backchannel xprt as long as server connection Multiple backchannels can share the same tcp connection; from rfc 5661 section 2.10.3.1: A connection's association with a session is not exclusive. A connection associated with the channel(s) of one session may be simultaneously associated with the channel(s) of other sessions including sessions associated with other client IDs. However, multiple backchannels share a connection, they must all share the same xid stream (hence the same rpc_xprt); the only way we have to match replies with calls at the rpc layer is using the xid. So, keep the rpc_xprt around as long as the connection lasts, in case we're asked to use the connection as a backchannel again. Requests to create new backchannel clients over a given server connection should results in creating new clients that reuse the existing rpc_xprt. But to start, just reject attempts to associate multiple rpc_xprt's with the same underlying bc_xprt. Signed-off-by: J. Bruce Fields --- net/sunrpc/xprt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/sunrpc/xprt.c') diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 4c8f18aff7c3..749ad15ae305 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -965,6 +965,7 @@ struct rpc_xprt *xprt_alloc(struct net *net, int size, int max_req) xprt = kzalloc(size, GFP_KERNEL); if (xprt == NULL) goto out; + kref_init(&xprt->kref); xprt->max_reqs = max_req; xprt->slot = kcalloc(max_req, sizeof(struct rpc_rqst), GFP_KERNEL); @@ -1102,7 +1103,6 @@ found: return xprt; } - kref_init(&xprt->kref); spin_lock_init(&xprt->transport_lock); spin_lock_init(&xprt->reserve_lock); -- cgit v1.2.3-70-g09d2 From f0418aa4b1103f959d64dc18273efa04ee0140e9 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Wed, 8 Dec 2010 13:48:19 -0500 Subject: rpc: allow xprt_class->setup to return a preexisting xprt This allows us to reuse the xprt associated with a server connection if one has already been set up. Signed-off-by: J. Bruce Fields --- include/linux/sunrpc/xprt.h | 1 + net/sunrpc/xprt.c | 3 +++ net/sunrpc/xprtsock.c | 18 +++++++++--------- 3 files changed, 13 insertions(+), 9 deletions(-) (limited to 'net/sunrpc/xprt.c') diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h index 89d10d279a20..bef0f535f746 100644 --- a/include/linux/sunrpc/xprt.h +++ b/include/linux/sunrpc/xprt.h @@ -321,6 +321,7 @@ void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie); #define XPRT_CLOSING (6) #define XPRT_CONNECTION_ABORT (7) #define XPRT_CONNECTION_CLOSE (8) +#define XPRT_INITIALIZED (9) static inline void xprt_set_connected(struct rpc_xprt *xprt) { diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 749ad15ae305..856274d7e85c 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1102,6 +1102,9 @@ found: -PTR_ERR(xprt)); return xprt; } + if (test_and_set_bit(XPRT_INITIALIZED, &xprt->state)) + /* ->setup returned a pre-initialized xprt: */ + return xprt; spin_lock_init(&xprt->transport_lock); spin_lock_init(&xprt->reserve_lock); diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 0ef4dd4414ec..ee091c869fcd 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -2359,6 +2359,15 @@ 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 + * export; 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); if (IS_ERR(xprt)) return xprt; @@ -2396,15 +2405,6 @@ static struct rpc_xprt *xs_setup_bc_tcp(struct xprt_create *args) xprt->address_strings[RPC_DISPLAY_PORT], xprt->address_strings[RPC_DISPLAY_PROTO]); - /* - * The backchannel uses the same socket connection as the - * forechannel - */ - if (args->bc_xprt->xpt_bc_xprt) { - /* XXX: actually, want to catch this case... */ - ret = ERR_PTR(-EINVAL); - goto out_err; - } /* * Once we've associated a backchannel xprt with a connection, * we want to keep it around as long as long as the connection -- cgit v1.2.3-70-g09d2