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/* Handle vlserver selection and rotation.
*
* Copyright (C) 2018 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 Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include "internal.h"
#include "afs_vl.h"
/*
* Begin an operation on a volume location server.
*/
bool afs_begin_vlserver_operation(struct afs_vl_cursor *vc, struct afs_cell *cell,
struct key *key)
{
memset(vc, 0, sizeof(*vc));
vc->cell = cell;
vc->key = key;
vc->error = -EDESTADDRREQ;
vc->ac.error = SHRT_MAX;
if (signal_pending(current)) {
vc->error = -EINTR;
vc->flags |= AFS_VL_CURSOR_STOP;
return false;
}
return true;
}
/*
* Begin iteration through a server list, starting with the last used server if
* possible, or the last recorded good server if not.
*/
static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
{
struct afs_cell *cell = vc->cell;
if (wait_on_bit(&cell->flags, AFS_CELL_FL_NO_LOOKUP_YET,
TASK_INTERRUPTIBLE)) {
vc->error = -ERESTARTSYS;
return false;
}
read_lock(&cell->vl_servers_lock);
vc->server_list = afs_get_vlserverlist(
rcu_dereference_protected(cell->vl_servers,
lockdep_is_held(&cell->vl_servers_lock)));
read_unlock(&cell->vl_servers_lock);
if (!vc->server_list || !vc->server_list->nr_servers)
return false;
vc->start = READ_ONCE(vc->server_list->index);
vc->index = vc->start;
return true;
}
/*
* Select the vlserver to use. May be called multiple times to rotate
* through the vlservers.
*/
bool afs_select_vlserver(struct afs_vl_cursor *vc)
{
struct afs_addr_list *alist;
struct afs_vlserver *vlserver;
int error = vc->ac.error;
_enter("%u/%u,%u/%u,%d,%d",
vc->index, vc->start,
vc->ac.index, vc->ac.start,
error, vc->ac.abort_code);
if (vc->flags & AFS_VL_CURSOR_STOP) {
_leave(" = f [stopped]");
return false;
}
/* Evaluate the result of the previous operation, if there was one. */
switch (error) {
case SHRT_MAX:
goto start;
default:
case 0:
/* Success or local failure. Stop. */
vc->error = error;
vc->flags |= AFS_VL_CURSOR_STOP;
_leave(" = f [okay/local %d]", vc->ac.error);
return false;
case -ECONNABORTED:
/* The far side rejected the operation on some grounds. This
* might involve the server being busy or the volume having been moved.
*/
switch (vc->ac.abort_code) {
case AFSVL_IO:
case AFSVL_BADVOLOPER:
case AFSVL_NOMEM:
/* The server went weird. */
vc->error = -EREMOTEIO;
//write_lock(&vc->cell->vl_servers_lock);
//vc->server_list->weird_mask |= 1 << vc->index;
//write_unlock(&vc->cell->vl_servers_lock);
goto next_server;
default:
vc->error = afs_abort_to_error(vc->ac.abort_code);
goto failed;
}
case -ENETUNREACH:
case -EHOSTUNREACH:
case -ECONNREFUSED:
case -ETIMEDOUT:
case -ETIME:
_debug("no conn %d", error);
vc->error = error;
goto iterate_address;
case -ECONNRESET:
_debug("call reset");
vc->error = error;
vc->flags |= AFS_VL_CURSOR_RETRY;
goto next_server;
}
restart_from_beginning:
_debug("restart");
afs_end_cursor(&vc->ac);
afs_put_vlserverlist(vc->cell->net, vc->server_list);
vc->server_list = NULL;
if (vc->flags & AFS_VL_CURSOR_RETRIED)
goto failed;
vc->flags |= AFS_VL_CURSOR_RETRIED;
start:
_debug("start");
/* TODO: Consider checking the VL server list */
if (!afs_start_vl_iteration(vc))
goto failed;
use_server:
_debug("use");
/* We're starting on a different vlserver from the list. We need to
* check it, find its address list and probe its capabilities before we
* use it.
*/
ASSERTCMP(vc->ac.alist, ==, NULL);
vlserver = vc->server_list->servers[vc->index].server;
// TODO: Check the vlserver occasionally
//if (!afs_check_vlserver_record(vc, vlserver))
// goto failed;
_debug("USING VLSERVER: %s", vlserver->name);
read_lock(&vlserver->lock);
alist = rcu_dereference_protected(vlserver->addresses,
lockdep_is_held(&vlserver->lock));
afs_get_addrlist(alist);
read_unlock(&vlserver->lock);
memset(&vc->ac, 0, sizeof(vc->ac));
/* Probe the current vlserver if we haven't done so yet. */
#if 0 // TODO
if (!test_bit(AFS_VLSERVER_FL_PROBED, &vlserver->flags)) {
vc->ac.alist = afs_get_addrlist(alist);
if (!afs_probe_vlserver(vc)) {
error = vc->ac.error;
switch (error) {
case -ENOMEM:
case -ERESTARTSYS:
case -EINTR:
goto failed_set_error;
default:
goto next_server;
}
}
}
#endif
if (!vc->ac.alist)
vc->ac.alist = alist;
else
afs_put_addrlist(alist);
vc->ac.start = READ_ONCE(alist->index);
vc->ac.index = vc->ac.start;
iterate_address:
ASSERT(vc->ac.alist);
_debug("iterate %d/%d", vc->ac.index, vc->ac.alist->nr_addrs);
/* Iterate over the current server's address list to try and find an
* address on which it will respond to us.
*/
if (!afs_iterate_addresses(&vc->ac))
goto next_server;
_leave(" = t %pISpc", &vc->ac.addr->transport);
return true;
next_server:
_debug("next");
afs_end_cursor(&vc->ac);
vc->index++;
if (vc->index >= vc->server_list->nr_servers)
vc->index = 0;
if (vc->index != vc->start)
goto use_server;
/* That's all the servers poked to no good effect. Try again if some
* of them were busy.
*/
if (vc->flags & AFS_VL_CURSOR_RETRY)
goto restart_from_beginning;
goto failed;
failed:
vc->flags |= AFS_VL_CURSOR_STOP;
afs_end_cursor(&vc->ac);
_leave(" = f [failed %d]", vc->error);
return false;
}
/*
* Tidy up a volume location server cursor and unlock the vnode.
*/
int afs_end_vlserver_operation(struct afs_vl_cursor *vc)
{
struct afs_net *net = vc->cell->net;
afs_end_cursor(&vc->ac);
afs_put_vlserverlist(net, vc->server_list);
if (vc->error == -ECONNABORTED)
vc->error = afs_abort_to_error(vc->ac.abort_code);
return vc->error;
}
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