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Commit 6b26cc8c authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
Browse files

sunrpc: Advertise maximum backchannel payload size 



RPC-over-RDMA transports have a limit on how large a backward
direction (backchannel) RPC message can be. Ensure that the NFSv4.x
CREATE_SESSION operation advertises this limit to servers.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Tested-by: default avatarSteve Wise <swise@opengridcomputing.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 4b9c7f9d

fs/nfs/nfs4proc.c

+6 −4
Original line number Diff line number Diff line
@@ -7371,9 +7371,11 @@ int nfs4_proc_get_lease_time(struct nfs_client *clp, struct nfs_fsinfo *fsinfo) 
 * always set csa_cachethis to FALSE because the current implementation

 * of the back channel DRC only supports caching the CB_SEQUENCE operation.

 */

static void nfs4_init_channel_attrs(struct nfs41_create_session_args *args)

static void nfs4_init_channel_attrs(struct nfs41_create_session_args *args,

				    struct rpc_clnt *clnt)

{

	unsigned int max_rqst_sz, max_resp_sz;

	unsigned int max_bc_payload = rpc_max_bc_payload(clnt);



	max_rqst_sz = NFS_MAX_FILE_IO_SIZE + nfs41_maxwrite_overhead;

	max_resp_sz = NFS_MAX_FILE_IO_SIZE + nfs41_maxread_overhead;
@@ -7391,8 +7393,8 @@ static void nfs4_init_channel_attrs(struct nfs41_create_session_args *args) 
		args->fc_attrs.max_ops, args->fc_attrs.max_reqs);



	/* Back channel attributes */

	args->bc_attrs.max_rqst_sz = PAGE_SIZE;

	args->bc_attrs.max_resp_sz = PAGE_SIZE;

	args->bc_attrs.max_rqst_sz = max_bc_payload;

	args->bc_attrs.max_resp_sz = max_bc_payload;

	args->bc_attrs.max_resp_sz_cached = 0;

	args->bc_attrs.max_ops = NFS4_MAX_BACK_CHANNEL_OPS;

	args->bc_attrs.max_reqs = NFS41_BC_MAX_CALLBACKS;
@@ -7496,7 +7498,7 @@ static int _nfs4_proc_create_session(struct nfs_client *clp, 
	};

	int status;



	nfs4_init_channel_attrs(&args);

	nfs4_init_channel_attrs(&args, clp->cl_rpcclient);

	args.flags = (SESSION4_PERSIST | SESSION4_BACK_CHAN);



	status = rpc_call_sync(session->clp->cl_rpcclient, &msg, RPC_TASK_TIMEOUT);

include/linux/sunrpc/clnt.h

+1 −0
Original line number Diff line number Diff line
@@ -176,6 +176,7 @@ void rpc_setbufsize(struct rpc_clnt *, unsigned int, unsigned int); 
int		rpc_protocol(struct rpc_clnt *);

struct net *	rpc_net_ns(struct rpc_clnt *);

size_t		rpc_max_payload(struct rpc_clnt *);

size_t		rpc_max_bc_payload(struct rpc_clnt *);

unsigned long	rpc_get_timeout(struct rpc_clnt *clnt);

void		rpc_force_rebind(struct rpc_clnt *);

size_t		rpc_peeraddr(struct rpc_clnt *, struct sockaddr *, size_t);

include/linux/sunrpc/xprt.h

+1 −0
Original line number Diff line number Diff line
@@ -142,6 +142,7 @@ struct rpc_xprt_ops { 
	int		(*bc_setup)(struct rpc_xprt *xprt,

				    unsigned int min_reqs);

	int		(*bc_up)(struct svc_serv *serv, struct net *net);

	size_t		(*bc_maxpayload)(struct rpc_xprt *xprt);

	void		(*bc_free_rqst)(struct rpc_rqst *rqst);

	void		(*bc_destroy)(struct rpc_xprt *xprt,

				      unsigned int max_reqs);

net/sunrpc/clnt.c

+17 −0
Original line number Diff line number Diff line
@@ -1413,6 +1413,23 @@ size_t rpc_max_payload(struct rpc_clnt *clnt) 
}

EXPORT_SYMBOL_GPL(rpc_max_payload);



/**

 * rpc_max_bc_payload - Get maximum backchannel payload size, in bytes

 * @clnt: RPC client to query

 */

size_t rpc_max_bc_payload(struct rpc_clnt *clnt)

{

	struct rpc_xprt *xprt;

	size_t ret;



	rcu_read_lock();

	xprt = rcu_dereference(clnt->cl_xprt);

	ret = xprt->ops->bc_maxpayload(xprt);

	rcu_read_unlock();

	return ret;

}

EXPORT_SYMBOL_GPL(rpc_max_bc_payload);



/**

 * rpc_get_timeout - Get timeout for transport in units of HZ

 * @clnt: RPC client to query

net/sunrpc/xprtrdma/backchannel.c

+16 −0
Original line number Diff line number Diff line
@@ -191,6 +191,22 @@ int xprt_rdma_bc_up(struct svc_serv *serv, struct net *net) 
	return 0;

}



/**

 * xprt_rdma_bc_maxpayload - Return maximum backchannel message size

 * @xprt: transport

 *

 * Returns maximum size, in bytes, of a backchannel message

 */

size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *xprt)

{

	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);

	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;

	size_t maxmsg;



	maxmsg = min_t(unsigned int, cdata->inline_rsize, cdata->inline_wsize);

	return maxmsg - RPCRDMA_HDRLEN_MIN;

}



/**

 * rpcrdma_bc_marshal_reply - Send backwards direction reply

 * @rqst: buffer containing RPC reply data