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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0a5143f2f8
Track VL servers as independent entities rather than lumping all their addresses together into one set and implement server-level rotation by: (1) Add the concept of a VL server list, where each server has its own separate address list. This code is similar to the FS server list. (2) Use the DNS resolver to retrieve a set of servers and their associated addresses, ports, preference and weight ratings. (3) In the case of a legacy DNS resolver or an address list given directly through /proc/net/afs/cells, create a list containing just a dummy server record and attach all the addresses to that. (4) Implement a simple rotation policy, for the moment ignoring the priorities and weights assigned to the servers. (5) Show the address list through /proc/net/afs/<cell>/vlservers. This also displays the source and status of the data as indicated by the upcall. Signed-off-by: David Howells <dhowells@redhat.com>
252 lines
5.9 KiB
C
252 lines
5.9 KiB
C
/* Handle vlserver selection and rotation.
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*
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* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/sched/signal.h>
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#include "internal.h"
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#include "afs_vl.h"
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/*
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* Begin an operation on a volume location server.
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*/
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bool afs_begin_vlserver_operation(struct afs_vl_cursor *vc, struct afs_cell *cell,
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struct key *key)
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{
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memset(vc, 0, sizeof(*vc));
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vc->cell = cell;
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vc->key = key;
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vc->error = -EDESTADDRREQ;
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vc->ac.error = SHRT_MAX;
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if (signal_pending(current)) {
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vc->error = -EINTR;
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vc->flags |= AFS_VL_CURSOR_STOP;
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return false;
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}
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return true;
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}
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/*
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* Begin iteration through a server list, starting with the last used server if
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* possible, or the last recorded good server if not.
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*/
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static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
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{
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struct afs_cell *cell = vc->cell;
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if (wait_on_bit(&cell->flags, AFS_CELL_FL_NO_LOOKUP_YET,
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TASK_INTERRUPTIBLE)) {
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vc->error = -ERESTARTSYS;
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return false;
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}
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read_lock(&cell->vl_servers_lock);
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vc->server_list = afs_get_vlserverlist(
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rcu_dereference_protected(cell->vl_servers,
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lockdep_is_held(&cell->vl_servers_lock)));
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read_unlock(&cell->vl_servers_lock);
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if (!vc->server_list || !vc->server_list->nr_servers)
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return false;
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vc->start = READ_ONCE(vc->server_list->index);
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vc->index = vc->start;
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return true;
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}
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/*
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* Select the vlserver to use. May be called multiple times to rotate
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* through the vlservers.
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*/
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bool afs_select_vlserver(struct afs_vl_cursor *vc)
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{
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struct afs_addr_list *alist;
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struct afs_vlserver *vlserver;
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int error = vc->ac.error;
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_enter("%u/%u,%u/%u,%d,%d",
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vc->index, vc->start,
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vc->ac.index, vc->ac.start,
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error, vc->ac.abort_code);
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if (vc->flags & AFS_VL_CURSOR_STOP) {
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_leave(" = f [stopped]");
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return false;
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}
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/* Evaluate the result of the previous operation, if there was one. */
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switch (error) {
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case SHRT_MAX:
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goto start;
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default:
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case 0:
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/* Success or local failure. Stop. */
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vc->error = error;
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vc->flags |= AFS_VL_CURSOR_STOP;
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_leave(" = f [okay/local %d]", vc->ac.error);
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return false;
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case -ECONNABORTED:
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/* The far side rejected the operation on some grounds. This
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* might involve the server being busy or the volume having been moved.
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*/
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switch (vc->ac.abort_code) {
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case AFSVL_IO:
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case AFSVL_BADVOLOPER:
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case AFSVL_NOMEM:
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/* The server went weird. */
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vc->error = -EREMOTEIO;
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//write_lock(&vc->cell->vl_servers_lock);
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//vc->server_list->weird_mask |= 1 << vc->index;
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//write_unlock(&vc->cell->vl_servers_lock);
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goto next_server;
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default:
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vc->error = afs_abort_to_error(vc->ac.abort_code);
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goto failed;
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}
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case -ENETUNREACH:
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case -EHOSTUNREACH:
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case -ECONNREFUSED:
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case -ETIMEDOUT:
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case -ETIME:
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_debug("no conn %d", error);
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vc->error = error;
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goto iterate_address;
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case -ECONNRESET:
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_debug("call reset");
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vc->error = error;
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vc->flags |= AFS_VL_CURSOR_RETRY;
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goto next_server;
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}
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restart_from_beginning:
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_debug("restart");
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afs_end_cursor(&vc->ac);
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afs_put_vlserverlist(vc->cell->net, vc->server_list);
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vc->server_list = NULL;
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if (vc->flags & AFS_VL_CURSOR_RETRIED)
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goto failed;
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vc->flags |= AFS_VL_CURSOR_RETRIED;
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start:
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_debug("start");
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/* TODO: Consider checking the VL server list */
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if (!afs_start_vl_iteration(vc))
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goto failed;
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use_server:
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_debug("use");
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/* We're starting on a different vlserver from the list. We need to
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* check it, find its address list and probe its capabilities before we
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* use it.
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*/
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ASSERTCMP(vc->ac.alist, ==, NULL);
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vlserver = vc->server_list->servers[vc->index].server;
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// TODO: Check the vlserver occasionally
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//if (!afs_check_vlserver_record(vc, vlserver))
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// goto failed;
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_debug("USING VLSERVER: %s", vlserver->name);
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read_lock(&vlserver->lock);
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alist = rcu_dereference_protected(vlserver->addresses,
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lockdep_is_held(&vlserver->lock));
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afs_get_addrlist(alist);
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read_unlock(&vlserver->lock);
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memset(&vc->ac, 0, sizeof(vc->ac));
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/* Probe the current vlserver if we haven't done so yet. */
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#if 0 // TODO
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if (!test_bit(AFS_VLSERVER_FL_PROBED, &vlserver->flags)) {
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vc->ac.alist = afs_get_addrlist(alist);
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if (!afs_probe_vlserver(vc)) {
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error = vc->ac.error;
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switch (error) {
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case -ENOMEM:
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case -ERESTARTSYS:
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case -EINTR:
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goto failed_set_error;
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default:
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goto next_server;
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}
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}
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}
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#endif
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if (!vc->ac.alist)
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vc->ac.alist = alist;
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else
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afs_put_addrlist(alist);
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vc->ac.start = READ_ONCE(alist->index);
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vc->ac.index = vc->ac.start;
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iterate_address:
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ASSERT(vc->ac.alist);
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_debug("iterate %d/%d", vc->ac.index, vc->ac.alist->nr_addrs);
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/* Iterate over the current server's address list to try and find an
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* address on which it will respond to us.
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*/
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if (!afs_iterate_addresses(&vc->ac))
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goto next_server;
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_leave(" = t %pISpc", &vc->ac.addr->transport);
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return true;
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next_server:
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_debug("next");
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afs_end_cursor(&vc->ac);
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vc->index++;
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if (vc->index >= vc->server_list->nr_servers)
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vc->index = 0;
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if (vc->index != vc->start)
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goto use_server;
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/* That's all the servers poked to no good effect. Try again if some
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* of them were busy.
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*/
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if (vc->flags & AFS_VL_CURSOR_RETRY)
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goto restart_from_beginning;
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goto failed;
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failed:
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vc->flags |= AFS_VL_CURSOR_STOP;
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afs_end_cursor(&vc->ac);
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_leave(" = f [failed %d]", vc->error);
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return false;
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}
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/*
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* Tidy up a volume location server cursor and unlock the vnode.
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*/
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int afs_end_vlserver_operation(struct afs_vl_cursor *vc)
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{
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struct afs_net *net = vc->cell->net;
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afs_end_cursor(&vc->ac);
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afs_put_vlserverlist(net, vc->server_list);
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if (vc->error == -ECONNABORTED)
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vc->error = afs_abort_to_error(vc->ac.abort_code);
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return vc->error;
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}
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