fs/afs/server.c - kernel/msm-4.9 - Gitiles

 /* server.c: AFS server record management
  *
  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  */

 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <rxrpc/peer.h>
 #include <rxrpc/connection.h>
 #include "volume.h"
 #include "cell.h"
 #include "server.h"
 #include "transport.h"
 #include "vlclient.h"
 #include "kafstimod.h"
 #include "internal.h"

 DEFINE_SPINLOCK(afs_server_peer_lock);

 #define FS_SERVICE_ID		1	/* AFS Volume Location Service ID */
 #define VL_SERVICE_ID		52	/* AFS Volume Location Service ID */

 static void __afs_server_timeout(struct afs_timer *timer)
 {
 	struct afs_server *server =
 		list_entry(timer, struct afs_server, timeout);

 	_debug("SERVER TIMEOUT [%p{u=%d}]",
 	       server, atomic_read(&server->usage));

 	afs_server_do_timeout(server);
 }

 static const struct afs_timer_ops afs_server_timer_ops = {
 	.timed_out	= __afs_server_timeout,
 };

 /*****************************************************************************/
 /*
  * lookup a server record in a cell
  * - TODO: search the cell's server list
  */
 int afs_server_lookup(struct afs_cell *cell, const struct in_addr *addr,
 		      struct afs_server **_server)
 {
 	struct afs_server *server, *active, *zombie;
 	int loop;

 	_enter("%p,%08x,", cell, ntohl(addr->s_addr));

 	/* allocate and initialise a server record */
 	server = kmalloc(sizeof(struct afs_server), GFP_KERNEL);
 	if (!server) {
 		_leave(" = -ENOMEM");
 		return -ENOMEM;
 	}

 	memset(server, 0, sizeof(struct afs_server));
 	atomic_set(&server->usage, 1);

 	INIT_LIST_HEAD(&server->link);
 	init_rwsem(&server->sem);
 	INIT_LIST_HEAD(&server->fs_callq);
 	spin_lock_init(&server->fs_lock);
 	INIT_LIST_HEAD(&server->cb_promises);
 	spin_lock_init(&server->cb_lock);

 	for (loop = 0; loop < AFS_SERVER_CONN_LIST_SIZE; loop++)
 		server->fs_conn_cnt[loop] = 4;

 	memcpy(&server->addr, addr, sizeof(struct in_addr));
 	server->addr.s_addr = addr->s_addr;

 	afs_timer_init(&server->timeout, &afs_server_timer_ops);

 	/* add to the cell */
 	write_lock(&cell->sv_lock);

 	/* check the active list */
 	list_for_each_entry(active, &cell->sv_list, link) {
 		if (active->addr.s_addr == addr->s_addr)
 			goto use_active_server;
 	}

 	/* check the inactive list */
 	spin_lock(&cell->sv_gylock);
 	list_for_each_entry(zombie, &cell->sv_graveyard, link) {
 		if (zombie->addr.s_addr == addr->s_addr)
 			goto resurrect_server;
 	}
 	spin_unlock(&cell->sv_gylock);

 	afs_get_cell(cell);
 	server->cell = cell;
 	list_add_tail(&server->link, &cell->sv_list);

 	write_unlock(&cell->sv_lock);

 	*_server = server;
 	_leave(" = 0 (%p)", server);
 	return 0;

 	/* found a matching active server */
  use_active_server:
 	_debug("active server");
 	afs_get_server(active);
 	write_unlock(&cell->sv_lock);

 	kfree(server);

 	*_server = active;
 	_leave(" = 0 (%p)", active);
 	return 0;

 	/* found a matching server in the graveyard, so resurrect it and
 	 * dispose of the new record */
  resurrect_server:
 	_debug("resurrecting server");

 	list_del(&zombie->link);
 	list_add_tail(&zombie->link, &cell->sv_list);
 	afs_get_server(zombie);
 	afs_kafstimod_del_timer(&zombie->timeout);
 	spin_unlock(&cell->sv_gylock);
 	write_unlock(&cell->sv_lock);

 	kfree(server);

 	*_server = zombie;
 	_leave(" = 0 (%p)", zombie);
 	return 0;

 } /* end afs_server_lookup() */

 /*****************************************************************************/
 /*
  * destroy a server record
  * - removes from the cell list
  */
 void afs_put_server(struct afs_server *server)
 {
 	struct afs_cell *cell;

 	if (!server)
 		return;

 	_enter("%p", server);

 	cell = server->cell;

 	/* sanity check */
 	BUG_ON(atomic_read(&server->usage) <= 0);

 	/* to prevent a race, the decrement and the dequeue must be effectively
 	 * atomic */
 	write_lock(&cell->sv_lock);

 	if (likely(!atomic_dec_and_test(&server->usage))) {
 		write_unlock(&cell->sv_lock);
 		_leave("");
 		return;
 	}

 	spin_lock(&cell->sv_gylock);
 	list_del(&server->link);
 	list_add_tail(&server->link, &cell->sv_graveyard);

 	/* time out in 10 secs */
 	afs_kafstimod_add_timer(&server->timeout, 10 * HZ);

 	spin_unlock(&cell->sv_gylock);
 	write_unlock(&cell->sv_lock);

 	_leave(" [killed]");
 } /* end afs_put_server() */

 /*****************************************************************************/
 /*
  * timeout server record
  * - removes from the cell's graveyard if the usage count is zero
  */
 void afs_server_do_timeout(struct afs_server *server)
 {
 	struct rxrpc_peer *peer;
 	struct afs_cell *cell;
 	int loop;

 	_enter("%p", server);

 	cell = server->cell;

 	BUG_ON(atomic_read(&server->usage) < 0);

 	/* remove from graveyard if still dead */
 	spin_lock(&cell->vl_gylock);
 	if (atomic_read(&server->usage) == 0)
 		list_del_init(&server->link);
 	else
 		server = NULL;
 	spin_unlock(&cell->vl_gylock);

 	if (!server) {
 		_leave("");
 		return; /* resurrected */
 	}

 	/* we can now destroy it properly */
 	afs_put_cell(cell);

 	/* uncross-point the structs under a global lock */
 	spin_lock(&afs_server_peer_lock);
 	peer = server->peer;
 	if (peer) {
 		server->peer = NULL;
 		peer->user = NULL;
 	}
 	spin_unlock(&afs_server_peer_lock);

 	/* finish cleaning up the server */
 	for (loop = AFS_SERVER_CONN_LIST_SIZE - 1; loop >= 0; loop--)
 		if (server->fs_conn[loop])
 			rxrpc_put_connection(server->fs_conn[loop]);

 	if (server->vlserver)
 		rxrpc_put_connection(server->vlserver);

 	kfree(server);

 	_leave(" [destroyed]");
 } /* end afs_server_do_timeout() */

 /*****************************************************************************/
 /*
  * get a callslot on a connection to the fileserver on the specified server
  */
 int afs_server_request_callslot(struct afs_server *server,
 				struct afs_server_callslot *callslot)
 {
 	struct afs_server_callslot *pcallslot;
 	struct rxrpc_connection *conn;
 	int nconn, ret;

 	_enter("%p,",server);

 	INIT_LIST_HEAD(&callslot->link);
 	callslot->task = current;
 	callslot->conn = NULL;
 	callslot->nconn = -1;
 	callslot->ready = 0;

 	ret = 0;
 	conn = NULL;

 	/* get hold of a callslot first */
 	spin_lock(&server->fs_lock);

 	/* resurrect the server if it's death timeout has expired */
 	if (server->fs_state) {
 		if (time_before(jiffies, server->fs_dead_jif)) {
 			ret = server->fs_state;
 			spin_unlock(&server->fs_lock);
 			_leave(" = %d [still dead]", ret);
 			return ret;
 		}

 		server->fs_state = 0;
 	}

 	/* try and find a connection that has spare callslots */
 	for (nconn = 0; nconn < AFS_SERVER_CONN_LIST_SIZE; nconn++) {
 		if (server->fs_conn_cnt[nconn] > 0) {
 			server->fs_conn_cnt[nconn]--;
 			spin_unlock(&server->fs_lock);
 			callslot->nconn = nconn;
 			goto obtained_slot;
 		}
 	}

 	/* none were available - wait interruptibly for one to become
 	 * available */
 	set_current_state(TASK_INTERRUPTIBLE);
 	list_add_tail(&callslot->link, &server->fs_callq);
 	spin_unlock(&server->fs_lock);

 	while (!callslot->ready && !signal_pending(current)) {
 		schedule();
 		set_current_state(TASK_INTERRUPTIBLE);
 	}

 	set_current_state(TASK_RUNNING);

 	/* even if we were interrupted we may still be queued */
 	if (!callslot->ready) {
 		spin_lock(&server->fs_lock);
 		list_del_init(&callslot->link);
 		spin_unlock(&server->fs_lock);
 	}

 	nconn = callslot->nconn;

 	/* if interrupted, we must release any slot we also got before
 	 * returning an error */
 	if (signal_pending(current)) {
 		ret = -EINTR;
 		goto error_release;
 	}

 	/* if we were woken up with an error, then pass that error back to the
 	 * called */
 	if (nconn < 0) {
 		_leave(" = %d", callslot->errno);
 		return callslot->errno;
 	}

 	/* were we given a connection directly? */
 	if (callslot->conn) {
 		/* yes - use it */
 		_leave(" = 0 (nc=%d)", nconn);
 		return 0;
 	}

 	/* got a callslot, but no connection */
  obtained_slot:

 	/* need to get hold of the RxRPC connection */
 	down_write(&server->sem);

 	/* quick check to see if there's an outstanding error */
 	ret = server->fs_state;
 	if (ret)
 		goto error_release_upw;

 	if (server->fs_conn[nconn]) {
 		/* reuse an existing connection */
 		rxrpc_get_connection(server->fs_conn[nconn]);
 		callslot->conn = server->fs_conn[nconn];
 	}
 	else {
 		/* create a new connection */
 		ret = rxrpc_create_connection(afs_transport,
 					      htons(7000),
 					      server->addr.s_addr,
 					      FS_SERVICE_ID,
 					      NULL,
 					      &server->fs_conn[nconn]);

 		if (ret < 0)
 			goto error_release_upw;

 		callslot->conn = server->fs_conn[0];
 		rxrpc_get_connection(callslot->conn);
 	}

 	up_write(&server->sem);

  	_leave(" = 0");
 	return 0;

 	/* handle an error occurring */
  error_release_upw:
 	up_write(&server->sem);

  error_release:
 	/* either release the callslot or pass it along to another deserving
 	 * task */
 	spin_lock(&server->fs_lock);

 	if (nconn < 0) {
 		/* no callslot allocated */
 	}
 	else if (list_empty(&server->fs_callq)) {
 		/* no one waiting */
 		server->fs_conn_cnt[nconn]++;
 		spin_unlock(&server->fs_lock);
 	}
 	else {
 		/* someone's waiting - dequeue them and wake them up */
 		pcallslot = list_entry(server->fs_callq.next,
 				       struct afs_server_callslot, link);
 		list_del_init(&pcallslot->link);

 		pcallslot->errno = server->fs_state;
 		if (!pcallslot->errno) {
 			/* pass them out callslot details */
 			callslot->conn = xchg(&pcallslot->conn,
 					      callslot->conn);
 			pcallslot->nconn = nconn;
 			callslot->nconn = nconn = -1;
 		}
 		pcallslot->ready = 1;
 		wake_up_process(pcallslot->task);
 		spin_unlock(&server->fs_lock);
 	}

 	rxrpc_put_connection(callslot->conn);
 	callslot->conn = NULL;

 	_leave(" = %d", ret);
 	return ret;

 } /* end afs_server_request_callslot() */

 /*****************************************************************************/
 /*
  * release a callslot back to the server
  * - transfers the RxRPC connection to the next pending callslot if possible
  */
 void afs_server_release_callslot(struct afs_server *server,
 				 struct afs_server_callslot *callslot)
 {
 	struct afs_server_callslot *pcallslot;

 	_enter("{ad=%08x,cnt=%u},{%d}",
 	       ntohl(server->addr.s_addr),
 	       server->fs_conn_cnt[callslot->nconn],
 	       callslot->nconn);

 	BUG_ON(callslot->nconn < 0);

 	spin_lock(&server->fs_lock);

 	if (list_empty(&server->fs_callq)) {
 		/* no one waiting */
 		server->fs_conn_cnt[callslot->nconn]++;
 		spin_unlock(&server->fs_lock);
 	}
 	else {
 		/* someone's waiting - dequeue them and wake them up */
 		pcallslot = list_entry(server->fs_callq.next,
 				       struct afs_server_callslot, link);
 		list_del_init(&pcallslot->link);

 		pcallslot->errno = server->fs_state;
 		if (!pcallslot->errno) {
 			/* pass them out callslot details */
 			callslot->conn = xchg(&pcallslot->conn, callslot->conn);
 			pcallslot->nconn = callslot->nconn;
 			callslot->nconn = -1;
 		}

 		pcallslot->ready = 1;
 		wake_up_process(pcallslot->task);
 		spin_unlock(&server->fs_lock);
 	}

 	rxrpc_put_connection(callslot->conn);

 	_leave("");
 } /* end afs_server_release_callslot() */

 /*****************************************************************************/
 /*
  * get a handle to a connection to the vlserver (volume location) on the
  * specified server
  */
 int afs_server_get_vlconn(struct afs_server *server,
 			  struct rxrpc_connection **_conn)
 {
 	struct rxrpc_connection *conn;
 	int ret;

 	_enter("%p,", server);

 	ret = 0;
 	conn = NULL;
 	down_read(&server->sem);

 	if (server->vlserver) {
 		/* reuse an existing connection */
 		rxrpc_get_connection(server->vlserver);
 		conn = server->vlserver;
 		up_read(&server->sem);
 	}
 	else {
 		/* create a new connection */
 		up_read(&server->sem);
 		down_write(&server->sem);
 		if (!server->vlserver) {
 			ret = rxrpc_create_connection(afs_transport,
 						      htons(7003),
 						      server->addr.s_addr,
 						      VL_SERVICE_ID,
 						      NULL,
 						      &server->vlserver);
 		}
 		if (ret == 0) {
 			rxrpc_get_connection(server->vlserver);
 			conn = server->vlserver;
 		}
 		up_write(&server->sem);
 	}

 	*_conn = conn;
 	_leave(" = %d", ret);
 	return ret;
 } /* end afs_server_get_vlconn() */
	/* server.c: AFS server record management
	*
	* Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

	#include <linux/sched.h>
	#include <linux/slab.h>
	#include <rxrpc/peer.h>
	#include <rxrpc/connection.h>
	#include "volume.h"
	#include "cell.h"
	#include "server.h"
	#include "transport.h"
	#include "vlclient.h"
	#include "kafstimod.h"
	#include "internal.h"

	DEFINE_SPINLOCK(afs_server_peer_lock);

	#define FS_SERVICE_ID 1 /* AFS Volume Location Service ID */
	#define VL_SERVICE_ID 52 /* AFS Volume Location Service ID */

	static void __afs_server_timeout(struct afs_timer *timer)
	{
	struct afs_server *server =
	list_entry(timer, struct afs_server, timeout);

	_debug("SERVER TIMEOUT [%p{u=%d}]",
	server, atomic_read(&server->usage));

	afs_server_do_timeout(server);
	}

	static const struct afs_timer_ops afs_server_timer_ops = {
	.timed_out = __afs_server_timeout,
	};

	/*****************************************************************************/
	/*
	* lookup a server record in a cell
	* - TODO: search the cell's server list
	*/
	int afs_server_lookup(struct afs_cell cell, const struct in_addr addr,
	struct afs_server **_server)
	{
	struct afs_server server, active, *zombie;
	int loop;

	_enter("%p,%08x,", cell, ntohl(addr->s_addr));

	/* allocate and initialise a server record */
	server = kmalloc(sizeof(struct afs_server), GFP_KERNEL);
	if (!server) {
	_leave(" = -ENOMEM");
	return -ENOMEM;
	}

	memset(server, 0, sizeof(struct afs_server));
	atomic_set(&server->usage, 1);

	INIT_LIST_HEAD(&server->link);
	init_rwsem(&server->sem);
	INIT_LIST_HEAD(&server->fs_callq);
	spin_lock_init(&server->fs_lock);
	INIT_LIST_HEAD(&server->cb_promises);
	spin_lock_init(&server->cb_lock);

	for (loop = 0; loop < AFS_SERVER_CONN_LIST_SIZE; loop++)
	server->fs_conn_cnt[loop] = 4;

	memcpy(&server->addr, addr, sizeof(struct in_addr));
	server->addr.s_addr = addr->s_addr;

	afs_timer_init(&server->timeout, &afs_server_timer_ops);

	/* add to the cell */
	write_lock(&cell->sv_lock);

	/* check the active list */
	list_for_each_entry(active, &cell->sv_list, link) {
	if (active->addr.s_addr == addr->s_addr)
	goto use_active_server;
	}

	/* check the inactive list */
	spin_lock(&cell->sv_gylock);
	list_for_each_entry(zombie, &cell->sv_graveyard, link) {
	if (zombie->addr.s_addr == addr->s_addr)
	goto resurrect_server;
	}
	spin_unlock(&cell->sv_gylock);

	afs_get_cell(cell);
	server->cell = cell;
	list_add_tail(&server->link, &cell->sv_list);

	write_unlock(&cell->sv_lock);

	*_server = server;
	_leave(" = 0 (%p)", server);
	return 0;

	/* found a matching active server */
	use_active_server:
	_debug("active server");
	afs_get_server(active);
	write_unlock(&cell->sv_lock);

	kfree(server);

	*_server = active;
	_leave(" = 0 (%p)", active);
	return 0;

	/* found a matching server in the graveyard, so resurrect it and
	* dispose of the new record */
	resurrect_server:
	_debug("resurrecting server");

	list_del(&zombie->link);
	list_add_tail(&zombie->link, &cell->sv_list);
	afs_get_server(zombie);
	afs_kafstimod_del_timer(&zombie->timeout);
	spin_unlock(&cell->sv_gylock);
	write_unlock(&cell->sv_lock);

	kfree(server);

	*_server = zombie;
	_leave(" = 0 (%p)", zombie);
	return 0;

	} /* end afs_server_lookup() */

	/*****************************************************************************/
	/*
	* destroy a server record
	* - removes from the cell list
	*/
	void afs_put_server(struct afs_server *server)
	{
	struct afs_cell *cell;

	if (!server)
	return;

	_enter("%p", server);

	cell = server->cell;

	/* sanity check */
	BUG_ON(atomic_read(&server->usage) <= 0);

	/* to prevent a race, the decrement and the dequeue must be effectively
	* atomic */
	write_lock(&cell->sv_lock);

	if (likely(!atomic_dec_and_test(&server->usage))) {
	write_unlock(&cell->sv_lock);
	_leave("");
	return;
	}

	spin_lock(&cell->sv_gylock);
	list_del(&server->link);
	list_add_tail(&server->link, &cell->sv_graveyard);

	/* time out in 10 secs */
	afs_kafstimod_add_timer(&server->timeout, 10 * HZ);

	spin_unlock(&cell->sv_gylock);
	write_unlock(&cell->sv_lock);

	_leave(" [killed]");
	} /* end afs_put_server() */

	/*****************************************************************************/
	/*
	* timeout server record
	* - removes from the cell's graveyard if the usage count is zero
	*/
	void afs_server_do_timeout(struct afs_server *server)
	{
	struct rxrpc_peer *peer;
	struct afs_cell *cell;
	int loop;

	_enter("%p", server);

	cell = server->cell;

	BUG_ON(atomic_read(&server->usage) < 0);

	/* remove from graveyard if still dead */
	spin_lock(&cell->vl_gylock);
	if (atomic_read(&server->usage) == 0)
	list_del_init(&server->link);
	else
	server = NULL;
	spin_unlock(&cell->vl_gylock);

	if (!server) {
	_leave("");
	return; /* resurrected */
	}

	/* we can now destroy it properly */
	afs_put_cell(cell);

	/* uncross-point the structs under a global lock */
	spin_lock(&afs_server_peer_lock);
	peer = server->peer;
	if (peer) {
	server->peer = NULL;
	peer->user = NULL;
	}
	spin_unlock(&afs_server_peer_lock);

	/* finish cleaning up the server */
	for (loop = AFS_SERVER_CONN_LIST_SIZE - 1; loop >= 0; loop--)
	if (server->fs_conn[loop])
	rxrpc_put_connection(server->fs_conn[loop]);

	if (server->vlserver)
	rxrpc_put_connection(server->vlserver);

	kfree(server);

	_leave(" [destroyed]");
	} /* end afs_server_do_timeout() */

	/*****************************************************************************/
	/*
	* get a callslot on a connection to the fileserver on the specified server
	*/
	int afs_server_request_callslot(struct afs_server *server,
	struct afs_server_callslot *callslot)
	{
	struct afs_server_callslot *pcallslot;
	struct rxrpc_connection *conn;
	int nconn, ret;

	_enter("%p,",server);

	INIT_LIST_HEAD(&callslot->link);
	callslot->task = current;
	callslot->conn = NULL;
	callslot->nconn = -1;
	callslot->ready = 0;

	ret = 0;
	conn = NULL;

	/* get hold of a callslot first */
	spin_lock(&server->fs_lock);

	/* resurrect the server if it's death timeout has expired */
	if (server->fs_state) {
	if (time_before(jiffies, server->fs_dead_jif)) {
	ret = server->fs_state;
	spin_unlock(&server->fs_lock);
	_leave(" = %d [still dead]", ret);
	return ret;
	}

	server->fs_state = 0;
	}

	/* try and find a connection that has spare callslots */
	for (nconn = 0; nconn < AFS_SERVER_CONN_LIST_SIZE; nconn++) {
	if (server->fs_conn_cnt[nconn] > 0) {
	server->fs_conn_cnt[nconn]--;
	spin_unlock(&server->fs_lock);
	callslot->nconn = nconn;
	goto obtained_slot;
	}
	}

	/* none were available - wait interruptibly for one to become
	* available */
	set_current_state(TASK_INTERRUPTIBLE);
	list_add_tail(&callslot->link, &server->fs_callq);
	spin_unlock(&server->fs_lock);

	while (!callslot->ready && !signal_pending(current)) {
	schedule();
	set_current_state(TASK_INTERRUPTIBLE);
	}

	set_current_state(TASK_RUNNING);

	/* even if we were interrupted we may still be queued */
	if (!callslot->ready) {
	spin_lock(&server->fs_lock);
	list_del_init(&callslot->link);
	spin_unlock(&server->fs_lock);
	}

	nconn = callslot->nconn;

	/* if interrupted, we must release any slot we also got before
	* returning an error */
	if (signal_pending(current)) {
	ret = -EINTR;
	goto error_release;
	}

	/* if we were woken up with an error, then pass that error back to the
	* called */
	if (nconn < 0) {
	_leave(" = %d", callslot->errno);
	return callslot->errno;
	}

	/* were we given a connection directly? */
	if (callslot->conn) {
	/* yes - use it */
	_leave(" = 0 (nc=%d)", nconn);
	return 0;
	}

	/* got a callslot, but no connection */
	obtained_slot:

	/* need to get hold of the RxRPC connection */
	down_write(&server->sem);

	/* quick check to see if there's an outstanding error */
	ret = server->fs_state;
	if (ret)
	goto error_release_upw;

	if (server->fs_conn[nconn]) {
	/* reuse an existing connection */
	rxrpc_get_connection(server->fs_conn[nconn]);
	callslot->conn = server->fs_conn[nconn];
	}
	else {
	/* create a new connection */
	ret = rxrpc_create_connection(afs_transport,
	htons(7000),
	server->addr.s_addr,
	FS_SERVICE_ID,
	NULL,
	&server->fs_conn[nconn]);

	if (ret < 0)
	goto error_release_upw;

	callslot->conn = server->fs_conn[0];
	rxrpc_get_connection(callslot->conn);
	}

	up_write(&server->sem);

	_leave(" = 0");
	return 0;

	/* handle an error occurring */
	error_release_upw:
	up_write(&server->sem);

	error_release:
	/* either release the callslot or pass it along to another deserving
	* task */
	spin_lock(&server->fs_lock);

	if (nconn < 0) {
	/* no callslot allocated */
	}
	else if (list_empty(&server->fs_callq)) {
	/* no one waiting */
	server->fs_conn_cnt[nconn]++;
	spin_unlock(&server->fs_lock);
	}
	else {
	/* someone's waiting - dequeue them and wake them up */
	pcallslot = list_entry(server->fs_callq.next,
	struct afs_server_callslot, link);
	list_del_init(&pcallslot->link);

	pcallslot->errno = server->fs_state;
	if (!pcallslot->errno) {
	/* pass them out callslot details */
	callslot->conn = xchg(&pcallslot->conn,
	callslot->conn);
	pcallslot->nconn = nconn;
	callslot->nconn = nconn = -1;
	}
	pcallslot->ready = 1;
	wake_up_process(pcallslot->task);
	spin_unlock(&server->fs_lock);
	}

	rxrpc_put_connection(callslot->conn);
	callslot->conn = NULL;

	_leave(" = %d", ret);
	return ret;

	} /* end afs_server_request_callslot() */

	/*****************************************************************************/
	/*
	* release a callslot back to the server
	* - transfers the RxRPC connection to the next pending callslot if possible
	*/
	void afs_server_release_callslot(struct afs_server *server,
	struct afs_server_callslot *callslot)
	{
	struct afs_server_callslot *pcallslot;

	_enter("{ad=%08x,cnt=%u},{%d}",
	ntohl(server->addr.s_addr),
	server->fs_conn_cnt[callslot->nconn],
	callslot->nconn);

	BUG_ON(callslot->nconn < 0);

	spin_lock(&server->fs_lock);

	if (list_empty(&server->fs_callq)) {
	/* no one waiting */
	server->fs_conn_cnt[callslot->nconn]++;
	spin_unlock(&server->fs_lock);
	}
	else {
	/* someone's waiting - dequeue them and wake them up */
	pcallslot = list_entry(server->fs_callq.next,
	struct afs_server_callslot, link);
	list_del_init(&pcallslot->link);

	pcallslot->errno = server->fs_state;
	if (!pcallslot->errno) {
	/* pass them out callslot details */
	callslot->conn = xchg(&pcallslot->conn, callslot->conn);
	pcallslot->nconn = callslot->nconn;
	callslot->nconn = -1;
	}

	pcallslot->ready = 1;
	wake_up_process(pcallslot->task);
	spin_unlock(&server->fs_lock);
	}

	rxrpc_put_connection(callslot->conn);

	_leave("");
	} /* end afs_server_release_callslot() */

	/*****************************************************************************/
	/*
	* get a handle to a connection to the vlserver (volume location) on the
	* specified server
	*/
	int afs_server_get_vlconn(struct afs_server *server,
	struct rxrpc_connection **_conn)
	{
	struct rxrpc_connection *conn;
	int ret;

	_enter("%p,", server);

	ret = 0;
	conn = NULL;
	down_read(&server->sem);

	if (server->vlserver) {
	/* reuse an existing connection */
	rxrpc_get_connection(server->vlserver);
	conn = server->vlserver;
	up_read(&server->sem);
	}
	else {
	/* create a new connection */
	up_read(&server->sem);
	down_write(&server->sem);
	if (!server->vlserver) {
	ret = rxrpc_create_connection(afs_transport,
	htons(7003),
	server->addr.s_addr,
	VL_SERVICE_ID,
	NULL,
	&server->vlserver);
	}
	if (ret == 0) {
	rxrpc_get_connection(server->vlserver);
	conn = server->vlserver;
	}
	up_write(&server->sem);
	}

	*_conn = conn;
	_leave(" = %d", ret);
	return ret;
	} /* end afs_server_get_vlconn() */