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Commit 55ae1aab authored by Ricardo Labiaga's avatar Ricardo Labiaga Committed by Benny Halevy
Browse files

nfs41: Add backchannel processing support to RPC state machine 



Adds rpc_run_bc_task() which is called by the NFS callback service to
process backchannel requests.  It performs similar work to rpc_run_task()
though "schedules" the backchannel task to be executed starting at the
call_trasmit state in the RPC state machine.

It also introduces some miscellaneous updates to the argument validation,
call_transmit, and transport cleanup functions to take into account
that there are now forechannel and backchannel tasks.

Backchannel requests do not carry an RPC message structure, since the
payload has already been XDR encoded using the existing NFSv4 callback
mechanism.

Introduce a new transmit state for the client to reply on to backchannel
requests.  This new state simply reserves the transport and issues the
reply.  In case of a connection related error, disconnects the transport and
drops the reply.  It requires the forechannel to re-establish the connection
and the server to retransmit the request, as stated in NFSv4.1 section
2.9.2 "Client and Server Transport Behavior".

Note: There is no need to loop attempting to reserve the transport.  If EAGAIN
is returned by xprt_prepare_transmit(), return with tk_status == 0,
setting tk_action to call_bc_transmit.  rpc_execute() will invoke it again
after the task is taken off the sleep queue.

[nfs41: rpc_run_bc_task() need not be exported outside RPC module]
[nfs41: New call_bc_transmit RPC state]
Signed-off-by: default avatarRicardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: default avatarBenny Halevy <bhalevy@panasas.com>
[nfs41: Backchannel: No need to loop in call_bc_transmit()]
Signed-off-by: default avatarAndy Adamson <andros@netapp.com>
Signed-off-by: default avatarRicardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: default avatarBenny Halevy <bhalevy@panasas.com>
[rpc_count_iostats incorrectly exits early]
Signed-off-by: default avatarRicardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: default avatarBenny Halevy <bhalevy@panasas.com>
[Convert rpc_reply_expected() to inline function]
[Remove unnecessary BUG_ON()]
[Rename variable]
Signed-off-by: default avatarRicardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: default avatarBenny Halevy <bhalevy@panasas.com>
parent 44b98efd

include/linux/sunrpc/sched.h

+2 −0
Original line number Diff line number Diff line
@@ -210,6 +210,8 @@ struct rpc_wait_queue { 
 */

struct rpc_task *rpc_new_task(const struct rpc_task_setup *);

struct rpc_task *rpc_run_task(const struct rpc_task_setup *);

struct rpc_task *rpc_run_bc_task(struct rpc_rqst *req,

				const struct rpc_call_ops *ops);

void		rpc_put_task(struct rpc_task *);

void		rpc_exit_task(struct rpc_task *);

void		rpc_release_calldata(const struct rpc_call_ops *, void *);

include/linux/sunrpc/xprt.h

+12 −0
Original line number Diff line number Diff line
@@ -215,6 +215,18 @@ struct rpc_xprt { 
						/* buffer in use */

#endif /* CONFIG_NFS_V4_1 */



#if defined(CONFIG_NFS_V4_1)

static inline int bc_prealloc(struct rpc_rqst *req)

{

	return test_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);

}

#else

static inline int bc_prealloc(struct rpc_rqst *req)

{

	return 0;

}

#endif /* CONFIG_NFS_V4_1 */



struct xprt_create {

	int			ident;		/* XPRT_TRANSPORT identifier */

	struct sockaddr *	srcaddr;	/* optional local address */

net/sunrpc/clnt.c

+116 −1
Original line number Diff line number Diff line
@@ -36,7 +36,9 @@ 
#include <linux/sunrpc/clnt.h>

#include <linux/sunrpc/rpc_pipe_fs.h>

#include <linux/sunrpc/metrics.h>

#include <linux/sunrpc/bc_xprt.h>



#include "sunrpc.h"



#ifdef RPC_DEBUG

# define RPCDBG_FACILITY	RPCDBG_CALL
@@ -63,6 +65,9 @@ static void call_decode(struct rpc_task *task); 
static void	call_bind(struct rpc_task *task);

static void	call_bind_status(struct rpc_task *task);

static void	call_transmit(struct rpc_task *task);

#if defined(CONFIG_NFS_V4_1)

static void	call_bc_transmit(struct rpc_task *task);

#endif /* CONFIG_NFS_V4_1 */

static void	call_status(struct rpc_task *task);

static void	call_transmit_status(struct rpc_task *task);

static void	call_refresh(struct rpc_task *task);
@@ -613,6 +618,50 @@ rpc_call_async(struct rpc_clnt *clnt, const struct rpc_message *msg, int flags, 
}

EXPORT_SYMBOL_GPL(rpc_call_async);



#if defined(CONFIG_NFS_V4_1)

/**

 * rpc_run_bc_task - Allocate a new RPC task for backchannel use, then run

 * rpc_execute against it

 * @ops: RPC call ops

 */

struct rpc_task *rpc_run_bc_task(struct rpc_rqst *req,

					const struct rpc_call_ops *tk_ops)

{

	struct rpc_task *task;

	struct xdr_buf *xbufp = &req->rq_snd_buf;

	struct rpc_task_setup task_setup_data = {

		.callback_ops = tk_ops,

	};



	dprintk("RPC: rpc_run_bc_task req= %p\n", req);

	/*

	 * Create an rpc_task to send the data

	 */

	task = rpc_new_task(&task_setup_data);

	if (!task) {

		xprt_free_bc_request(req);

		goto out;

	}

	task->tk_rqstp = req;



	/*

	 * Set up the xdr_buf length.

	 * This also indicates that the buffer is XDR encoded already.

	 */

	xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +

			xbufp->tail[0].iov_len;



	task->tk_action = call_bc_transmit;

	atomic_inc(&task->tk_count);

	BUG_ON(atomic_read(&task->tk_count) != 2);

	rpc_execute(task);



out:

	dprintk("RPC: rpc_run_bc_task: task= %p\n", task);

	return task;

}

#endif /* CONFIG_NFS_V4_1 */



void

rpc_call_start(struct rpc_task *task)

{
@@ -1098,7 +1147,7 @@ call_transmit(struct rpc_task *task) 
	 * in order to allow access to the socket to other RPC requests.

	 */

	call_transmit_status(task);

	if (task->tk_msg.rpc_proc->p_decode != NULL)

	if (rpc_reply_expected(task))

		return;

	task->tk_action = rpc_exit_task;

	rpc_wake_up_queued_task(&task->tk_xprt->pending, task);
@@ -1133,6 +1182,72 @@ call_transmit_status(struct rpc_task *task) 
	}

}



#if defined(CONFIG_NFS_V4_1)

/*

 * 5b.	Send the backchannel RPC reply.  On error, drop the reply.  In

 * addition, disconnect on connectivity errors.

 */

static void

call_bc_transmit(struct rpc_task *task)

{

	struct rpc_rqst *req = task->tk_rqstp;



	BUG_ON(task->tk_status != 0);

	task->tk_status = xprt_prepare_transmit(task);

	if (task->tk_status == -EAGAIN) {

		/*

		 * Could not reserve the transport. Try again after the

		 * transport is released.

		 */

		task->tk_status = 0;

		task->tk_action = call_bc_transmit;

		return;

	}



	task->tk_action = rpc_exit_task;

	if (task->tk_status < 0) {

		printk(KERN_NOTICE "RPC: Could not send backchannel reply "

			"error: %d\n", task->tk_status);

		return;

	}



	xprt_transmit(task);

	xprt_end_transmit(task);

	dprint_status(task);

	switch (task->tk_status) {

	case 0:

		/* Success */

		break;

	case -EHOSTDOWN:

	case -EHOSTUNREACH:

	case -ENETUNREACH:

	case -ETIMEDOUT:

		/*

		 * Problem reaching the server.  Disconnect and let the

		 * forechannel reestablish the connection.  The server will

		 * have to retransmit the backchannel request and we'll

		 * reprocess it.  Since these ops are idempotent, there's no

		 * need to cache our reply at this time.

		 */

		printk(KERN_NOTICE "RPC: Could not send backchannel reply "

			"error: %d\n", task->tk_status);

		xprt_conditional_disconnect(task->tk_xprt,

			req->rq_connect_cookie);

		break;

	default:

		/*

		 * We were unable to reply and will have to drop the

		 * request.  The server should reconnect and retransmit.

		 */

		BUG_ON(task->tk_status == -EAGAIN);

		printk(KERN_NOTICE "RPC: Could not send backchannel reply "

			"error: %d\n", task->tk_status);

		break;

	}

	rpc_wake_up_queued_task(&req->rq_xprt->pending, task);

}

#endif /* CONFIG_NFS_V4_1 */



/*

 * 6.	Sort out the RPC call status

 */

net/sunrpc/stats.c

+4 −2
Original line number Diff line number Diff line
@@ -141,12 +141,14 @@ EXPORT_SYMBOL_GPL(rpc_free_iostats); 
void rpc_count_iostats(struct rpc_task *task)

{

	struct rpc_rqst *req = task->tk_rqstp;

	struct rpc_iostats *stats = task->tk_client->cl_metrics;

	struct rpc_iostats *stats;

	struct rpc_iostats *op_metrics;

	long rtt, execute, queue;



	if (!stats || !req)

	if (!task->tk_client || !task->tk_client->cl_metrics || !req)

		return;



	stats = task->tk_client->cl_metrics;

	op_metrics = &stats[task->tk_msg.rpc_proc->p_statidx];



	op_metrics->om_ops++;

net/sunrpc/sunrpc.h

0 → 100644
+37 −0
Original line number Diff line number Diff line 
/******************************************************************************



(c) 2008 NetApp.  All Rights Reserved.



NetApp provides this source code under the GPL v2 License.

The GPL v2 license is available at

http://opensource.org/licenses/gpl-license.php.



THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR

CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.



******************************************************************************/



/*

 * Functions and macros used internally by RPC

 */



#ifndef _NET_SUNRPC_SUNRPC_H

#define _NET_SUNRPC_SUNRPC_H



static inline int rpc_reply_expected(struct rpc_task *task)

{

	return (task->tk_msg.rpc_proc != NULL) &&

		(task->tk_msg.rpc_proc->p_decode != NULL);

}



#endif /* _NET_SUNRPC_SUNRPC_H */