text: // SPDX-License-Identifier: GPL-2.0-or-later
  /* Maintain an RxRPC server socket to do AFS communications through
   *
   * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   */
  
  #include <linux/slab.h>
  #include <linux/sched/signal.h>
  
  #include <net/sock.h>
  #include <net/af_rxrpc.h>
  #include "internal.h"
  #include "afs_cm.h"
  #include "protocol_yfs.h"
  
  struct workqueue_struct *afs_async_calls;
  
  static void afs_wake_up_call_waiter(struct sock *, struct rxrpc_call *, unsigned long);
  static void afs_wake_up_async_call(struct sock *, struct rxrpc_call *, unsigned long);
  static void afs_delete_async_call(struct work_struct *);
  static void afs_process_async_call(struct work_struct *);
  static void afs_rx_new_call(struct sock *, struct rxrpc_call *, unsigned long);
  static void afs_rx_discard_new_call(struct rxrpc_call *, unsigned long);
  static int afs_deliver_cm_op_id(struct afs_call *);
  
  /* asynchronous incoming call initial processing */
  static const struct afs_call_type afs_RXCMxxxx = {
  	.name		= "CB.xxxx",
  	.deliver	= afs_deliver_cm_op_id,
  };
  
  /*
   * open an RxRPC socket and bind it to be a server for callback notifications
   * - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
   */
  int afs_open_socket(struct afs_net *net)
  {
  	struct sockaddr_rxrpc srx;
  	struct socket *socket;
  	unsigned int min_level;
  	int ret;
  
  	_enter("");
  
  	ret = sock_create_kern(net->net, AF_RXRPC, SOCK_DGRAM, PF_INET6, &socket);
  	if (ret < 0)
  		goto error_1;
  
  	socket->sk->sk_allocation = GFP_NOFS;
  
  	/* bind the callback manager's address to make this a server socket */
  	memset(&srx, 0, sizeof(srx));
  	srx.srx_family			= AF_RXRPC;
  	srx.srx_service			= CM_SERVICE;
  	srx.transport_type		= SOCK_DGRAM;
  	srx.transport_len		= sizeof(srx.transport.sin6);
  	srx.transport.sin6.sin6_family	= AF_INET6;
  	srx.transport.sin6.sin6_port	= htons(AFS_CM_PORT);
  
  	min_level = RXRPC_SECURITY_ENCRYPT;
  	ret = kernel_setsockopt(socket, SOL_RXRPC, RXRPC_MIN_SECURITY_LEVEL,
  				(void *)&min_level, sizeof(min_level));
  	if (ret < 0)
  		goto error_2;
  
  	ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
  	if (ret == -EADDRINUSE) {
  		srx.transport.sin6.sin6_port = 0;
  		ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
  	}
  	if (ret < 0)
  		goto error_2;
  
  	srx.srx_service = YFS_CM_SERVICE;
  	ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
  	if (ret < 0)
  		goto error_2;
  
  	/* Ideally, we'd turn on service upgrade here, but we can't because
  	 * OpenAFS is buggy and leaks the userStatus field from packet to
  	 * packet and between FS packets and CB packets - so if we try to do an
  	 * upgrade on an FS packet, OpenAFS will leak that into the CB packet
  	 * it sends back to us.
  	 */
  
  	rxrpc_kernel_new_call_notification(socket, afs_rx_new_call,
  					   afs_rx_discard_new_call);
  
  	ret = kernel_listen(socket, INT_MAX);
  	if (ret < 0)
  		goto error_2;
  
  	net->socket = socket;
  	afs_charge_preallocation(&net->charge_preallocation_work);
  	_leave(" = 0");
  	return 0;
  
  error_2:
  	sock_release(socket);
  error_1:
  	_leave(" = %d", ret);
  	return ret;
  }
  
  /*
   * close the RxRPC socket AFS was using
   */
  void afs_close_socket(struct afs_net *net)
  {
  	_enter("");
  
  	kernel_listen(net->socket, 0);
  	flush_workqueue(afs_async_calls);
  
  	if (net->spare_incoming_call) {
  		afs_put_call(net->spare_incoming_call);
  		net->spare_incoming_call = NULL;
  	}
  
  	_debug("outstanding %u", atomic_read(&net->nr_outstanding_calls));
  	wait_var_event(&net->nr_outstanding_calls,
  		       !atomic_read(&net->nr_outstanding_calls));
  	_debug("no outstanding calls");
  
  	kernel_sock_shutdown(net->socket, SHUT_RDWR);
  	flush_workqueue(afs_async_calls);
  	sock_release(net->socket);
  
  	_debug("dework");
  	_leave("");
  }
  
  /*
   * Allocate a call.
   */
  static struct afs_call *afs_alloc_call(struct afs_net *net,
  				       const struct afs_call_type *type,
  				       gfp_t gfp)
  {
  	struct afs_call *call;
  	int o;
  
  	call = kzalloc(sizeof(*call), gfp);
  	if (!call)
  		return NULL;
  
  	call->type = type;
  	call->net = net;
  	call->debug_id = atomic_inc_return(&rxrpc_debug_id);
  	atomic_set(&call->usage, 1);
  	INIT_WORK(&call->async_work, afs_process_async_call);
  	init_waitqueue_head(&call->waitq);
  	spin_lock_init(&call->state_lock);
  	call->_iter = &call->iter;
  
  	o = atomic_inc_return(&net->nr_outstanding_calls);
  	trace_afs_call(call, afs_call_trace_alloc, 1, o,
  		       __builtin_return_address(0));
  	return call;
  }
  
  /*
   * Dispose of a reference on a call.
   */
  void afs_put_call(struct afs_call *call)
  {
  	struct afs_net *net = call->net;
  	int n = atomic_dec_return(&call->usage);
  	int o = atomic_read(&net->nr_outstanding_calls);
  
  	trace_afs_call(call, afs_call_trace_put, n + 1, o,
  		       __builtin_return_address(0));
  
  	ASSERTCMP(n, >=, 0);
  	if (n == 0) {
  		ASSERT(!work_pending(&call->async_work));
  		ASSERT(call->type->name != NULL);
  
  		if (call->rxcall) {
  			rxrpc_kernel_end_call(net->socket, call->rxcall);
  			call->rxcall = NULL;
  		}
  		if (call->type->destructor)
  			call->type->destructor(call);
  
  		afs_put_server(call->net, call->server);
  		afs_put_cb_interest(call->net, call->cbi);
  		afs_put_addrlist(call->alist);
  		kfree(call->request);
  
  		trace_afs_call(call, afs_call_trace_free, 0, o,
  			       __builtin_return_address(0));
  		kfree(call);
  
  		o = atomic_dec_return(&net->nr_outstanding_calls);
  		if (o == 0)
  			wake_up_var(&net->nr_outstanding_calls);
  	}
  }
  
  static struct afs_call *afs_get_call(struct afs_call *call,
  				     enum afs_call_trace why)
  {
  	int u = atomic_inc_return(&call->usage);
  
  	trace_afs_call(call, why, u,
  		       atomic_read(&call->net->nr_outstanding_calls),
  		       __builtin_return_address(0));
  	return call;
  }
  
  /*
   * Queue the call for actual work.
   */
  static void afs_queue_call_work(struct afs_call *call)
  {
  	if (call->type->work) {
  		INIT_WORK(&call->work, call->type->work);
  
  		afs_get_call(call, afs_call_trace_work);
  		if (!queue_work(afs_wq, &call->work))
  			afs_put_call(call);
  	}
  }
  
  /*
   * allocate a call with flat request and reply buffers
   */
  struct afs_call *afs_alloc_flat_call(struct afs_net *net,
  				     const struct afs_call_type *type,
  				     size_t request_size, size_t reply_max)
  {
  	struct afs_call *call;
  
  	call = afs_alloc_call(net, type, GFP_NOFS);
  	if (!call)
  		goto nomem_call;
  
  	if (request_size) {
  		call->request_size = request_size;
  		call->request = kmalloc(request_size, GFP_NOFS);
  		if (!call->request)
  			goto nomem_free;
  	}
  
  	if (reply_max) {
  		call->reply_max = reply_max;
  		call->buffer = kmalloc(reply_max, GFP_NOFS);
  		if (!call->buffer)
  			goto nomem_free;
  	}
  
  	afs_extract_to_buf(call, call->reply_max);
  	call->operation_ID = type->op;
  	init_waitqueue_head(&call->waitq);
  	return call;
  
  nomem_free:
  	afs_put_call(call);
  nomem_call:
  	return NULL;
  }
  
  /*
   * clean up a call with flat buffer
   */
  void afs_flat_call_destructor(struct afs_call *call)
  {
  	_enter("");
  
  	kfree(call->request);
  	call->request = NULL;
  	kfree(call->buffer);
  	call->buffer = NULL;
  }
  
  #define AFS_BVEC_MAX 8
  
  /*
   * Load the given bvec with the next few pages.
   */
  static void afs_load_bvec(struct afs_call *call, struct msghdr *msg,
  			  struct bio_vec *bv, pgoff_t first, pgoff_t last,
  			  unsigned offset)
  {
  	struct page *pages[AFS_BVEC_MAX];
  	unsigned int nr, n, i, to, bytes = 0;
  
  	nr = min_t(pgoff_t, last - first + 1, AFS_BVEC_MAX);
  	n = find_get_pages_contig(call->mapping, first, nr, pages);
  	ASSERTCMP(n, ==, nr);
  
  	msg->msg_flags |= MSG_MORE;
  	for (i = 0; i < nr; i++) {
  		to = PAGE_SIZE;
  		if (first + i >= last) {
  			to = call->last_to;
  			msg->msg_flags &= ~MSG_MORE;
  		}
  		bv[i].bv_page = pages[i];
  		bv[i].bv_len = to - offset;
  		bv[i].bv_offset = offset;
  		bytes += to - offset;
  		offset = 0;
  	}
  
  	iov_iter_bvec(&msg->msg_iter, WRITE, bv, nr, bytes);
  }
  
  /*
   * Advance the AFS call state when the RxRPC call ends the transmit phase.
   */
  static void afs_notify_end_request_tx(struct sock *sock,
  				      struct rxrpc_call *rxcall,
  				      unsigned long call_user_ID)
  {
  	struct afs_call *call = (struct afs_call *)call_user_ID;
  
  	afs_set_call_state(call, AFS_CALL_CL_REQUESTING, AFS_CALL_CL_AWAIT_REPLY);
  }
  
  /*
   * attach the data from a bunch of pages on an inode to a call
   */
  static int afs_send_pages(struct afs_call *call, struct msghdr *msg)
  {
  	struct bio_vec bv[AFS_BVEC_MAX];
  	unsigned int bytes, nr, loop, offset;
  	pgoff_t first = call->first, last = call->last;
  	int ret;
  
  	offset = call->first_offset;
  	call->first_offset = 0;
  
  	do {
  		afs_load_bvec(call, msg, bv, first, last, offset);
  		trace_afs_send_pages(call, msg, first, last, offset);
  
  		offset = 0;
  		bytes = msg->msg_iter.count;
  		nr = msg->msg_iter.nr_segs;
  
  		ret = rxrpc_kernel_send_data(call->net->socket, call->rxcall, msg,
  					     bytes, afs_notify_end_request_tx);
  		for (loop = 0; loop < nr; loop++)
  			put_page(bv[loop].bv_page);
  		if (ret < 0)
  			break;
  
  		first += nr;
  	} while (first <= last);
  
  	trace_afs_sent_pages(call, call->first, last, first, ret);
  	return ret;
  }
  
  /*
   * Initiate a call and synchronously queue up the parameters for dispatch.  Any
   * error is stored into the call struct, which the caller must check for.
   */
  void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
  {
  	struct sockaddr_rxrpc *srx = &ac->alist->addrs[ac->index];
  	struct rxrpc_call *rxcall;
  	struct msghdr msg;
  	struct kvec iov[1];
  	s64 tx_total_len;
  	int ret;
  
  	_enter(",{%pISp},", &srx->transport);
  
  	ASSERT(call->type != NULL);
  	ASSERT(call->type->name != NULL);
  
  	_debug("____MAKE %p{%s,%x} [%d]____",
  	       call, call->type->name, key_serial(call->key),
  	       atomic_read(&call->net->nr_outstanding_calls));
  
  	call->addr_ix = ac->index;
  	call->alist = afs_get_addrlist(ac->alist);
  
  	/* Work out the length we're going to transmit.  This is awkward for
  	 * calls such as FS.StoreData where there's an extra injection of data
  	 * after the initial fixed part.
  	 */
  	tx_total_len = call->request_size;
  	if (call->send_pages) {
  		if (call->last == call->first) {
  			tx_total_len += call->last_to - call->first_offset;
  		} else {
  			/* It looks mathematically like you should be able to
  			 * combine the following lines with the ones above, but
  			 * unsigned arithmetic is fun when it wraps...
  			 */
  			tx_total_len += PAGE_SIZE - call->first_offset;
  			tx_total_len += call->last_to;
  			tx_total_len += (call->last - call->first - 1) * PAGE_SIZE;
  		}
  	}
  
  	/* If the call is going to be asynchronous, we need an extra ref for
  	 * the call to hold itself so the caller need not hang on to its ref.
  	 */
  	if (call->async)
  		afs_get_call(call, afs_call_trace_get);
  
  	/* create a call */
  	rxcall = rxrpc_kernel_begin_call(call->net->socket, srx, call->key,
  					 (unsigned long)call,
  					 tx_total_len, gfp,
  					 (call->async ?
  					  afs_wake_up_async_call :
  					  afs_wake_up_call_waiter),
  					 call->upgrade,
  					 call->intr,
  					 call->debug_id);
  	if (IS_ERR(rxcall)) {
  		ret = PTR_ERR(rxcall);
  		call->error = ret;
  		goto error_kill_call;
  	}
  
  	call->rxcall = rxcall;
  
  	if (call->max_lifespan)
  		rxrpc_kernel_set_max_life(call->net->socket, rxcall,
  					  call->max_lifespan);
  
  	/* send the request */
  	iov[0].iov_base	= call->request;
  	iov[0].iov_len	= call->request_size;
  
  	msg.msg_name		= NULL;
  	msg.msg_namelen		= 0;
  	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, call->request_size);
  	msg.msg_control		= NULL;
  	msg.msg_controllen	= 0;
  	msg.msg_flags		= MSG_WAITALL | (call->send_pages ? MSG_MORE : 0);
  
  	ret = rxrpc_kernel_send_data(call->net->socket, rxcall,
  				     &msg, call->request_size,
  				     afs_notify_end_request_tx);
  	if (ret < 0)
  		goto error_do_abort;
  
  	if (call->send_pages) {
  		ret = afs_send_pages(call, &msg);
  		if (ret < 0)
  			goto error_do_abort;
  	}
  
  	/* Note that at this point, we may have received the reply or an abort
  	 * - and an asynchronous call may already have completed.
  	 *
  	 * afs_wait_for_call_to_complete(call, ac)
  	 * must be called to synchronously clean up.
  	 */
  	return;
  
  error_do_abort:
  	if (ret != -ECONNABORTED) {
  		rxrpc_kernel_abort_call(call->net->socket, rxcall,
  					RX_USER_ABORT, ret, "KSD");
  	} else {
  		iov_iter_kvec(&msg.msg_iter, READ, NULL, 0, 0);
  		rxrpc_kernel_recv_data(call->net->socket, rxcall,
  				       &msg.msg_iter, false,
  				       &call->abort_code, &call->service_id);
  		ac->abort_code = call->abort_code;
  		ac->responded = true;
  	}
  	call->error = ret;
  	trace_afs_call_done(call);
  error_kill_call:
  	if (call->type->done)
  		call->type->done(call);
  
  	/* We need to dispose of the extra ref we grabbed for an async call.
  	 * The call, however, might be queued on afs_async_calls and we need to
  	 * make sure we don't get any more notifications that might requeue it.
  	 */
  	if (call->rxcall) {
  		rxrpc_kernel_end_call(call->net->socket, call->rxcall);
  		call->rxcall = NULL;
  	}
  	if (call->async) {
  		if (cancel_work_sync(&call->async_work))
  			afs_put_call(call);
  		afs_put_call(call);
  	}
  
  	ac->error = ret;
  	call->state = AFS_CALL_COMPLETE;
  	_leave(" = %d", ret);
  }
  
  /*
   * deliver messages to a call
   */
  static void afs_deliver_to_call(struct afs_call *call)
  {
  	enum afs_call_state state;
  	u32 abort_code, remote_abort = 0;
  	int ret;
  
  	_enter("%s", call->type->name);
  
  	while (state = READ_ONCE(call->state),
  	       state == AFS_CALL_CL_AWAIT_REPLY ||
  	       state == AFS_CALL_SV_AWAIT_OP_ID ||
  	       state == AFS_CALL_SV_AWAIT_REQUEST ||
  	       state == AFS_CALL_SV_AWAIT_ACK
  	       ) {
  		if (state == AFS_CALL_SV_AWAIT_ACK) {
  			iov_iter_kvec(&call->iter, READ, NULL, 0, 0);
  			ret = rxrpc_kernel_recv_data(call->net->socket,
  						     call->rxcall, &call->iter,
  						     false, &remote_abort,
  						     &call->service_id);
  			trace_afs_receive_data(call, &call->iter, false, ret);
  
  			if (ret == -EINPROGRESS || ret == -EAGAIN)
  				return;
  			if (ret < 0 || ret == 1) {
  				if (ret == 1)
  					ret = 0;
  				goto call_complete;
  			}
  			return;
  		}
  
  		if (!call->have_reply_time &&
  		    rxrpc_kernel_get_reply_time(call->net->socket,
  						call->rxcall,
  						&call->reply_time))
  			call->have_reply_time = true;
  
  		ret = call->type->deliver(call);
  		state = READ_ONCE(call->state);
  		switch (ret) {
  		case 0:
  			afs_queue_call_work(call);
  			if (state == AFS_CALL_CL_PROC_REPLY) {
  				if (call->cbi)
  					set_bit(AFS_SERVER_FL_MAY_HAVE_CB,
  						&call->cbi->server->flags);
  				goto call_complete;
  			}
  			ASSERTCMP(state, >, AFS_CALL_CL_PROC_REPLY);
  			goto done;
  		case -EINPROGRESS:
  		case -EAGAIN:
  			goto out;
  		case -ECONNABORTED:
  			ASSERTCMP(state, ==, AFS_CALL_COMPLETE);
  			goto done;
  		case -ENOTSUPP:
  			abort_code = RXGEN_OPCODE;
  			rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
  						abort_code, ret, "KIV");
  			goto local_abort;
  		case -EIO:
  			pr_err("kAFS: Call %u in bad state %u\n",
  			       call->debug_id, state);
  			/* Fall through */
  		case -ENODATA:
  		case -EBADMSG:
  		case -EMSGSIZE:
  			abort_code = RXGEN_CC_UNMARSHAL;
  			if (state != AFS_CALL_CL_AWAIT_REPLY)
  				abort_code = RXGEN_SS_UNMARSHAL;
  			rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
  						abort_code, ret, "KUM");
  			goto local_abort;
  		default:
  			abort_code = RX_USER_ABORT;
  			rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
  						abort_code, ret, "KER");
  			goto local_abort;
  		}
  	}
  
  done:
  	if (call->type->done)
  		call->type->done(call);
  	if (state == AFS_CALL_COMPLETE && call->incoming)
  		afs_put_call(call);
  out:
  	_leave("");
  	return;
  
  local_abort:
  	abort_code = 0;
  call_complete:
  	afs_set_call_complete(call, ret, remote_abort);
  	state = AFS_CALL_COMPLETE;
  	goto done;
  }
  
  /*
   * Wait synchronously for a call to complete and clean up the call struct.
   */
  long afs_wait_for_call_to_complete(struct afs_call *call,
  				   struct afs_addr_cursor *ac)
  {
  	signed long rtt2, timeout;
  	long ret;
  	bool stalled = false;
  	u64 rtt;
  	u32 life, last_life;
  	bool rxrpc_complete = false;
  
  	DECLARE_WAITQUEUE(myself, current);
  
  	_enter("");
  
  	ret = call->error;
  	if (ret < 0)
  		goto out;
  
  	rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
  	rtt2 = nsecs_to_jiffies64(rtt) * 2;
  	if (rtt2 < 2)
  		rtt2 = 2;
  
  	timeout = rtt2;
  	rxrpc_kernel_check_life(call->net->socket, call->rxcall, &last_life);
  
  	add_wait_queue(&call->waitq, &myself);
  	for (;;) {
  		set_current_state(TASK_UNINTERRUPTIBLE);
  
  		/* deliver any messages that are in the queue */
  		if (!afs_check_call_state(call, AFS_CALL_COMPLETE) &&
  		    call->need_attention) {
  			call->need_attention = false;
  			__set_current_state(TASK_RUNNING);
  			afs_deliver_to_call(call);
  			continue;
  		}
  
  		if (afs_check_call_state(call, AFS_CALL_COMPLETE))
  			break;
  
  		if (!rxrpc_kernel_check_life(call->net->socket, call->rxcall, &life)) {
  			/* rxrpc terminated the call. */
  			rxrpc_complete = true;
  			break;
  		}
  
  		if (call->intr && timeout == 0 &&
  		    life == last_life && signal_pending(current)) {
  			if (stalled)
  				break;
  			__set_current_state(TASK_RUNNING);
  			rxrpc_kernel_probe_life(call->net->socket, call->rxcall);
  			timeout = rtt2;
  			stalled = true;
  			continue;
  		}
  
  		if (life != last_life) {
  			timeout = rtt2;
  			last_life = life;
  			stalled = false;
  		}
  
  		timeout = schedule_timeout(timeout);
  	}
  
  	remove_wait_queue(&call->waitq, &myself);
  	__set_current_state(TASK_RUNNING);
  
  	if (!afs_check_call_state(call, AFS_CALL_COMPLETE)) {
  		if (rxrpc_complete) {
  			afs_set_call_complete(call, call->error, call->abort_code);
  		} else {
  			/* Kill off the call if it's still live. */
  			_debug("call interrupted");
  			if (rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
  						    RX_USER_ABORT, -EINTR, "KWI"))
  				afs_set_call_complete(call, -EINTR, 0);
  		}
  	}
  
  	spin_lock_bh(&call->state_lock);
  	ac->abort_code = call->abort_code;
  	ac->error = call->error;
  	spin_unlock_bh(&call->state_lock);
  
  	ret = ac->error;
  	switch (ret) {
  	case 0:
  		ret = call->ret0;
  		call->ret0 = 0;
  
  		/* Fall through */
  	case -ECONNABORTED:
  		ac->responded = true;
  		break;
  	}
  
  out:
  	_debug("call complete");
  	afs_put_call(call);
  	_leave(" = %p", (void *)ret);
  	return ret;
  }
  
  /*
   * wake up a waiting call
   */
  static void afs_wake_up_call_waiter(struct sock *sk, struct rxrpc_call *rxcall,
  				    unsigned long call_user_ID)
  {
  	struct afs_call *call = (struct afs_call *)call_user_ID;
  
  	call->need_attention = true;
  	wake_up(&call->waitq);
  }
  
  /*
   * wake up an asynchronous call
   */
  static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall,
  				   unsigned long call_user_ID)
  {
  	struct afs_call *call = (struct afs_call *)call_user_ID;
  	int u;
  
  	trace_afs_notify_call(rxcall, call);
  	call->need_attention = true;
  
  	u = atomic_fetch_add_unless(&call->usage, 1, 0);
  	if (u != 0) {
  		trace_afs_call(call, afs_call_trace_wake, u,
  			       atomic_read(&call->net->nr_outstanding_calls),
  			       __builtin_return_address(0));
  
  		if (!queue_work(afs_async_calls, &call->async_work))
  			afs_put_call(call);
  	}
  }
  
  /*
   * Delete an asynchronous call.  The work item carries a ref to the call struct
   * that we need to release.
   */
  static void afs_delete_async_call(struct work_struct *work)
  {
  	struct afs_call *call = container_of(work, struct afs_call, async_work);
  
  	_enter("");
  
  	afs_put_call(call);
  
  	_leave("");
  }
  
  /*
   * Perform I/O processing on an asynchronous call.  The work item carries a ref
   * to the call struct that we either need to release or to pass on.
   */
  static void afs_process_async_call(struct work_struct *work)
  {
  	struct afs_call *call = container_of(work, struct afs_call, async_work);
  
  	_enter("");
  
  	if (call->state < AFS_CALL_COMPLETE && call->need_attention) {
  		call->need_attention = false;
  		afs_deliver_to_call(call);
  	}
  
  	if (call->state == AFS_CALL_COMPLETE) {
  		/* We have two refs to release - one from the alloc and one
  		 * queued with the work item - and we can't just deallocate the
  		 * call because the work item may be queued again.
  		 */
  		call->async_work.func = afs_delete_async_call;
  		if (!queue_work(afs_async_calls, &call->async_work))
  			afs_put_call(call);
  	}
  
  	afs_put_call(call);
  	_leave("");
  }
  
  static void afs_rx_attach(struct rxrpc_call *rxcall, unsigned long user_call_ID)
  {
  	struct afs_call *call = (struct afs_call *)user_call_ID;
  
  	call->rxcall = rxcall;
  }
  
  /*
   * Charge the incoming call preallocation.
   */
  void afs_charge_preallocation(struct work_struct *work)
  {
  	struct afs_net *net =
  		container_of(work, struct afs_net, charge_preallocation_work);
  	struct afs_call *call = net->spare_incoming_call;
  
  	for (;;) {
  		if (!call) {
  			call = afs_alloc_call(net, &afs_RXCMxxxx, GFP_KERNEL);
  			if (!call)
  				break;
  
  			call->async = true;
  			call->state = AFS_CALL_SV_AWAIT_OP_ID;
  			init_waitqueue_head(&call->waitq);
  			afs_extract_to_tmp(call);
  		}
  
  		if (rxrpc_kernel_charge_accept(net->socket,
  					       afs_wake_up_async_call,
  					       afs_rx_attach,
  					       (unsigned long)call,
  					       GFP_KERNEL,
  					       call->debug_id) < 0)
  			break;
  		call = NULL;
  	}
  	net->spare_incoming_call = call;
  }
  
  /*
   * Discard a preallocated call when a socket is shut down.
   */
  static void afs_rx_discard_new_call(struct rxrpc_call *rxcall,
  				    unsigned long user_call_ID)
  {
  	struct afs_call *call = (struct afs_call *)user_call_ID;
  
  	call->rxcall = NULL;
  	afs_put_call(call);
  }
  
  /*
   * Notification of an incoming call.
   */
  static void afs_rx_new_call(struct sock *sk, struct rxrpc_call *rxcall,
  			    unsigned long user_call_ID)
  {
  	struct afs_net *net = afs_sock2net(sk);
  
  	queue_work(afs_wq, &net->charge_preallocation_work);
  }
  
  /*
   * Grab the operation ID from an incoming cache manager call.  The socket
   * buffer is discarded on error or if we don't yet have sufficient data.
   */
  static int afs_deliver_cm_op_id(struct afs_call *call)
  {
  	int ret;
  
  	_enter("{%zu}", iov_iter_count(call->_iter));
  
  	/* the operation ID forms the first four bytes of the request data */
  	ret = afs_extract_data(call, true);
  	if (ret < 0)
  		return ret;
  
  	call->operation_ID = ntohl(call->tmp);
  	afs_set_call_state(call, AFS_CALL_SV_AWAIT_OP_ID, AFS_CALL_SV_AWAIT_REQUEST);
  
  	/* ask the cache manager to route the call (it'll change the call type
  	 * if successful) */
  	if (!afs_cm_incoming_call(call))
  		return -ENOTSUPP;
  
  	trace_afs_cb_call(call);
  
  	/* pass responsibility for the remainer of this message off to the
  	 * cache manager op */
  	return call->type->deliver(call);
  }
  
  /*
   * Advance the AFS call state when an RxRPC service call ends the transmit
   * phase.
   */
  static void afs_notify_end_reply_tx(struct sock *sock,
  				    struct rxrpc_call *rxcall,
  				    unsigned long call_user_ID)
  {
  	struct afs_call *call = (struct afs_call *)call_user_ID;
  
  	afs_set_call_state(call, AFS_CALL_SV_REPLYING, AFS_CALL_SV_AWAIT_ACK);
  }
  
  /*
   * send an empty reply
   */
  void afs_send_empty_reply(struct afs_call *call)
  {
  	struct afs_net *net = call->net;
  	struct msghdr msg;
  
  	_enter("");
  
  	rxrpc_kernel_set_tx_length(net->socket, call->rxcall, 0);
  
  	msg.msg_name		= NULL;
  	msg.msg_namelen		= 0;
  	iov_iter_kvec(&msg.msg_iter, WRITE, NULL, 0, 0);
  	msg.msg_control		= NULL;
  	msg.msg_controllen	= 0;
  	msg.msg_flags		= 0;
  
  	switch (rxrpc_kernel_send_data(net->socket, call->rxcall, &msg, 0,
  				       afs_notify_end_reply_tx)) {
  	case 0:
  		_leave(" [replied]");
  		return;
  
  	case -ENOMEM:
  		_debug("oom");
  		rxrpc_kernel_abort_call(net->socket, call->rxcall,
  					RX_USER_ABORT, -ENOMEM, "KOO");
  		/* Fall through */
  	default:
  		_leave(" [error]");
  		return;
  	}
  }
  
  /*
   * send a simple reply
   */
  void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
  {
  	struct afs_net *net = call->net;
  	struct msghdr msg;
  	struct kvec iov[1];
  	int n;
  
  	_enter("");
  
  	rxrpc_kernel_set_tx_length(net->socket, call->rxcall, len);
  
  	iov[0].iov_base		= (void *) buf;
  	iov[0].iov_len		= len;
  	msg.msg_name		= NULL;
  	msg.msg_namelen		= 0;
  	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, len);
  	msg.msg_control		= NULL;
  	msg.msg_controllen	= 0;
  	msg.msg_flags		= 0;
  
  	n = rxrpc_kernel_send_data(net->socket, call->rxcall, &msg, len,
  				   afs_notify_end_reply_tx);
  	if (n >= 0) {
  		/* Success */
  		_leave(" [replied]");
  		return;
  	}
  
  	if (n == -ENOMEM) {
  		_debug("oom");
  		rxrpc_kernel_abort_call(net->socket, call->rxcall,
  					RX_USER_ABORT, -ENOMEM, "KOO");
  	}
  	_leave(" [error]");
  }
  
  /*
   * Extract a piece of data from the received data socket buffers.
   */
  int afs_extract_data(struct afs_call *call, bool want_more)
  {
  	struct afs_net *net = call->net;
  	struct iov_iter *iter = call->_iter;
  	enum afs_call_state state;
  	u32 remote_abort = 0;
  	int ret;
  
  	_enter("{%s,%zu},%d", call->type->name, iov_iter_count(iter), want_more);
  
  	ret = rxrpc_kernel_recv_data(net->socket, call->rxcall, iter,
  				     want_more, &remote_abort,
  				     &call->service_id);
  	if (ret == 0 || ret == -EAGAIN)
  		return ret;
  
  	state = READ_ONCE(call->state);
  	if (ret == 1) {
  		switch (state) {
  		case AFS_CALL_CL_AWAIT_REPLY:
  			afs_set_call_state(call, state, AFS_CALL_CL_PROC_REPLY);
  			break;
  		case AFS_CALL_SV_AWAIT_REQUEST:
  			afs_set_call_state(call, state, AFS_CALL_SV_REPLYING);
  			break;
  		case AFS_CALL_COMPLETE:
  			kdebug("prem complete %d", call->error);
  			return afs_io_error(call, afs_io_error_extract);
  		default:
  			break;
  		}
  		return 0;
  	}
  
  	afs_set_call_complete(call, ret, remote_abort);
  	return ret;
  }
  
  /*
   * Log protocol error production.
   */
  noinline int afs_protocol_error(struct afs_call *call, int error,
  				enum afs_eproto_cause cause)
  {
  	trace_afs_protocol_error(call, error, cause);
  	return error;
  }
  