linux-imx

/* 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->untried = (1UL << vc->server_list->nr_servers) - 1;

    vc->index = -1;

    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;

    struct afs_error e;

    u32 rtt;

    int error = vc->ac.error, i;

​

    _enter("%lx[%d],%lx[%d],%d,%d",

           vc->untried, vc->index,

           vc->ac.tried, vc->ac.index,

           error, vc->ac.abort_code);

​

    if (vc->flags & AFS_VL_CURSOR_STOP) {

        _leave(" = f [stopped]");

        return false;

    }

​

    vc->nr_iterations++;

​

    /* Evaluate the result of the previous operation, if there was one. */

    switch (error) {

    case SHRT_MAX: