config.c

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/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2011 Red Hat, Inc.  All rights reserved.
**
**  This copyrighted material is made available to anyone wishing to use,
**  modify, copy, or redistribute it subject to the terms and conditions
**  of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/configfs.h>
#include <linux/slab.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/dlmconstants.h>
#include <net/ipv6.h>
#include <net/sock.h>

#include "config.h"
#include "lowcomms.h"

/*
 * /config/dlm/<cluster>/spaces/<space>/nodes/<node>/nodeid
 * /config/dlm/<cluster>/spaces/<space>/nodes/<node>/weight
 * /config/dlm/<cluster>/comms/<comm>/nodeid
 * /config/dlm/<cluster>/comms/<comm>/local
 * /config/dlm/<cluster>/comms/<comm>/addr      (write only)
 * /config/dlm/<cluster>/comms/<comm>/addr_list (read only)
 * The <cluster> level is useless, but I haven't figured out how to avoid it.
 */

static struct config_group *space_list;
static struct config_group *comm_list;
static struct dlm_comm *local_comm;
static uint32_t dlm_comm_count;

struct dlm_clusters;
struct dlm_cluster;
struct dlm_spaces;
struct dlm_space;
struct dlm_comms;
struct dlm_comm;
struct dlm_nodes;
struct dlm_node;

static struct config_group *make_cluster(struct config_group *, const char *);
static void drop_cluster(struct config_group *, struct config_item *);
static void release_cluster(struct config_item *);
static struct config_group *make_space(struct config_group *, const char *);
static void drop_space(struct config_group *, struct config_item *);
static void release_space(struct config_item *);
static struct config_item *make_comm(struct config_group *, const char *);
static void drop_comm(struct config_group *, struct config_item *);
static void release_comm(struct config_item *);
static struct config_item *make_node(struct config_group *, const char *);
static void drop_node(struct config_group *, struct config_item *);
static void release_node(struct config_item *);

static ssize_t show_cluster(struct config_item *i, struct configfs_attribute *a,
                char *buf);
static ssize_t store_cluster(struct config_item *i,
                 struct configfs_attribute *a,
                 const char *buf, size_t len);
static ssize_t show_comm(struct config_item *i, struct configfs_attribute *a,
             char *buf);
static ssize_t store_comm(struct config_item *i, struct configfs_attribute *a,
              const char *buf, size_t len);
static ssize_t show_node(struct config_item *i, struct configfs_attribute *a,
             char *buf);
static ssize_t store_node(struct config_item *i, struct configfs_attribute *a,
              const char *buf, size_t len);

static ssize_t comm_nodeid_read(struct dlm_comm *cm, char *buf);
static ssize_t comm_nodeid_write(struct dlm_comm *cm, const char *buf,
                size_t len);
static ssize_t comm_local_read(struct dlm_comm *cm, char *buf);
static ssize_t comm_local_write(struct dlm_comm *cm, const char *buf,
                size_t len);
static ssize_t comm_addr_write(struct dlm_comm *cm, const char *buf,
                size_t len);
static ssize_t comm_addr_list_read(struct dlm_comm *cm, char *buf);
static ssize_t node_nodeid_read(struct dlm_node *nd, char *buf);
static ssize_t node_nodeid_write(struct dlm_node *nd, const char *buf,
                size_t len);
static ssize_t node_weight_read(struct dlm_node *nd, char *buf);
static ssize_t node_weight_write(struct dlm_node *nd, const char *buf,
                size_t len);

struct dlm_cluster {
    struct config_group group;
    unsigned int cl_tcp_port;
    unsigned int cl_buffer_size;
    unsigned int cl_rsbtbl_size;
    unsigned int cl_recover_timer;
    unsigned int cl_toss_secs;
    unsigned int cl_scan_secs;
    unsigned int cl_log_debug;
    unsigned int cl_protocol;
    unsigned int cl_timewarn_cs;
    unsigned int cl_waitwarn_us;
    unsigned int cl_new_rsb_count;
    unsigned int cl_recover_callbacks;
    char cl_cluster_name[DLM_LOCKSPACE_LEN];
};

enum {
    CLUSTER_ATTR_TCP_PORT = 0,
    CLUSTER_ATTR_BUFFER_SIZE,
    CLUSTER_ATTR_RSBTBL_SIZE,
    CLUSTER_ATTR_RECOVER_TIMER,
    CLUSTER_ATTR_TOSS_SECS,
    CLUSTER_ATTR_SCAN_SECS,
    CLUSTER_ATTR_LOG_DEBUG,
    CLUSTER_ATTR_PROTOCOL,
    CLUSTER_ATTR_TIMEWARN_CS,
    CLUSTER_ATTR_WAITWARN_US,
    CLUSTER_ATTR_NEW_RSB_COUNT,
    CLUSTER_ATTR_RECOVER_CALLBACKS,
    CLUSTER_ATTR_CLUSTER_NAME,
};

struct cluster_attribute {
    struct configfs_attribute attr;
    ssize_t (*show)(struct dlm_cluster *, char *);
    ssize_t (*store)(struct dlm_cluster *, const char *, size_t);
};

static ssize_t cluster_cluster_name_read(struct dlm_cluster *cl, char *buf)
{
    return sprintf(buf, "%s\n", cl->cl_cluster_name);
}

static ssize_t cluster_cluster_name_write(struct dlm_cluster *cl,
                      const char *buf, size_t len)
{
    strncpy(dlm_config.ci_cluster_name, buf, DLM_LOCKSPACE_LEN);
    strncpy(cl->cl_cluster_name, buf, DLM_LOCKSPACE_LEN);
    return len;
}

static struct cluster_attribute cluster_attr_cluster_name = {
    .attr   = { .ca_owner = THIS_MODULE,
                    .ca_name = "cluster_name",
                    .ca_mode = S_IRUGO | S_IWUSR },
    .show   = cluster_cluster_name_read,
    .store  = cluster_cluster_name_write,
};

static ssize_t cluster_set(struct dlm_cluster *cl, unsigned int *cl_field,
               int *info_field, int check_zero,
               const char *buf, size_t len)
{
    unsigned int x;

    if (!capable(CAP_SYS_ADMIN))
        return -EACCES;

    x = simple_strtoul(buf, NULL, 0);

    if (check_zero && !x)
        return -EINVAL;

    *cl_field = x;
    *info_field = x;

    return len;
}

#define CLUSTER_ATTR(name, check_zero)                                        \
static ssize_t name##_write(struct dlm_cluster *cl, const char *buf, size_t len) \
{                                                                             \
    return cluster_set(cl, &cl->cl_##name, &dlm_config.ci_##name,         \
               check_zero, buf, len);                             \
}                                                                             \
static ssize_t name##_read(struct dlm_cluster *cl, char *buf)                 \
{                                                                             \
    return snprintf(buf, PAGE_SIZE, "%u\n", cl->cl_##name);               \
}                                                                             \
static struct cluster_attribute cluster_attr_##name =                         \
__CONFIGFS_ATTR(name, 0644, name##_read, name##_write)

CLUSTER_ATTR(tcp_port, 1);
CLUSTER_ATTR(buffer_size, 1);
CLUSTER_ATTR(rsbtbl_size, 1);
CLUSTER_ATTR(recover_timer, 1);
CLUSTER_ATTR(toss_secs, 1);
CLUSTER_ATTR(scan_secs, 1);
CLUSTER_ATTR(log_debug, 0);
CLUSTER_ATTR(protocol, 0);
CLUSTER_ATTR(timewarn_cs, 1);
CLUSTER_ATTR(waitwarn_us, 0);
CLUSTER_ATTR(new_rsb_count, 0);
CLUSTER_ATTR(recover_callbacks, 0);

static struct configfs_attribute *cluster_attrs[] = {
    [CLUSTER_ATTR_TCP_PORT] = &cluster_attr_tcp_port.attr,
    [CLUSTER_ATTR_BUFFER_SIZE] = &cluster_attr_buffer_size.attr,
    [CLUSTER_ATTR_RSBTBL_SIZE] = &cluster_attr_rsbtbl_size.attr,
    [CLUSTER_ATTR_RECOVER_TIMER] = &cluster_attr_recover_timer.attr,
    [CLUSTER_ATTR_TOSS_SECS] = &cluster_attr_toss_secs.attr,
    [CLUSTER_ATTR_SCAN_SECS] = &cluster_attr_scan_secs.attr,
    [CLUSTER_ATTR_LOG_DEBUG] = &cluster_attr_log_debug.attr,
    [CLUSTER_ATTR_PROTOCOL] = &cluster_attr_protocol.attr,
    [CLUSTER_ATTR_TIMEWARN_CS] = &cluster_attr_timewarn_cs.attr,
    [CLUSTER_ATTR_WAITWARN_US] = &cluster_attr_waitwarn_us.attr,
    [CLUSTER_ATTR_NEW_RSB_COUNT] = &cluster_attr_new_rsb_count.attr,
    [CLUSTER_ATTR_RECOVER_CALLBACKS] = &cluster_attr_recover_callbacks.attr,
    [CLUSTER_ATTR_CLUSTER_NAME] = &cluster_attr_cluster_name.attr,
    NULL,
};

enum {
    COMM_ATTR_NODEID = 0,
    COMM_ATTR_LOCAL,
    COMM_ATTR_ADDR,
    COMM_ATTR_ADDR_LIST,
};

struct comm_attribute {
    struct configfs_attribute attr;
    ssize_t (*show)(struct dlm_comm *, char *);
    ssize_t (*store)(struct dlm_comm *, const char *, size_t);
};

static struct comm_attribute comm_attr_nodeid = {
    .attr   = { .ca_owner = THIS_MODULE,
                    .ca_name = "nodeid",
                    .ca_mode = S_IRUGO | S_IWUSR },
    .show   = comm_nodeid_read,
    .store  = comm_nodeid_write,
};

static struct comm_attribute comm_attr_local = {
    .attr   = { .ca_owner = THIS_MODULE,
                    .ca_name = "local",
                    .ca_mode = S_IRUGO | S_IWUSR },
    .show   = comm_local_read,
    .store  = comm_local_write,
};

static struct comm_attribute comm_attr_addr = {
    .attr   = { .ca_owner = THIS_MODULE,
                    .ca_name = "addr",
                    .ca_mode = S_IWUSR },
    .store  = comm_addr_write,
};

static struct comm_attribute comm_attr_addr_list = {
    .attr   = { .ca_owner = THIS_MODULE,
                    .ca_name = "addr_list",
                    .ca_mode = S_IRUGO },
    .show   = comm_addr_list_read,
};

static struct configfs_attribute *comm_attrs[] = {
    [COMM_ATTR_NODEID] = &comm_attr_nodeid.attr,
    [COMM_ATTR_LOCAL] = &comm_attr_local.attr,
    [COMM_ATTR_ADDR] = &comm_attr_addr.attr,
    [COMM_ATTR_ADDR_LIST] = &comm_attr_addr_list.attr,
    NULL,
};

enum {
    NODE_ATTR_NODEID = 0,
    NODE_ATTR_WEIGHT,
};

struct node_attribute {
    struct configfs_attribute attr;
    ssize_t (*show)(struct dlm_node *, char *);
    ssize_t (*store)(struct dlm_node *, const char *, size_t);
};

static struct node_attribute node_attr_nodeid = {
    .attr   = { .ca_owner = THIS_MODULE,
                    .ca_name = "nodeid",
                    .ca_mode = S_IRUGO | S_IWUSR },
    .show   = node_nodeid_read,
    .store  = node_nodeid_write,
};

static struct node_attribute node_attr_weight = {
    .attr   = { .ca_owner = THIS_MODULE,
                    .ca_name = "weight",
                    .ca_mode = S_IRUGO | S_IWUSR },
    .show   = node_weight_read,
    .store  = node_weight_write,
};

static struct configfs_attribute *node_attrs[] = {
    [NODE_ATTR_NODEID] = &node_attr_nodeid.attr,
    [NODE_ATTR_WEIGHT] = &node_attr_weight.attr,
    NULL,
};

struct dlm_clusters {
    struct configfs_subsystem subsys;
};

struct dlm_spaces {
    struct config_group ss_group;
};

struct dlm_space {
    struct config_group group;
    struct list_head members;
    struct mutex members_lock;
    int members_count;
};

struct dlm_comms {
    struct config_group cs_group;
};

struct dlm_comm {
    struct config_item item;
    int seq;
    int nodeid;
    int local;
    int addr_count;
    struct sockaddr_storage *addr[DLM_MAX_ADDR_COUNT];
};

struct dlm_nodes {
    struct config_group ns_group;
};

struct dlm_node {
    struct config_item item;
    struct list_head list; /* space->members */
    int nodeid;
    int weight;
    int new;
    int comm_seq; /* copy of cm->seq when nd->nodeid is set */
};

static struct configfs_group_operations clusters_ops = {
    .make_group = make_cluster,
    .drop_item = drop_cluster,
};

static struct configfs_item_operations cluster_ops = {
    .release = release_cluster,
    .show_attribute = show_cluster,
    .store_attribute = store_cluster,
};

static struct configfs_group_operations spaces_ops = {
    .make_group = make_space,
    .drop_item = drop_space,
};

static struct configfs_item_operations space_ops = {
    .release = release_space,
};

static struct configfs_group_operations comms_ops = {
    .make_item = make_comm,
    .drop_item = drop_comm,
};

static struct configfs_item_operations comm_ops = {
    .release = release_comm,
    .show_attribute = show_comm,
    .store_attribute = store_comm,
};

static struct configfs_group_operations nodes_ops = {
    .make_item = make_node,
    .drop_item = drop_node,
};

static struct configfs_item_operations node_ops = {
    .release = release_node,
    .show_attribute = show_node,
    .store_attribute = store_node,
};

static struct config_item_type clusters_type = {
    .ct_group_ops = &clusters_ops,
    .ct_owner = THIS_MODULE,
};

static struct config_item_type cluster_type = {
    .ct_item_ops = &cluster_ops,
    .ct_attrs = cluster_attrs,
    .ct_owner = THIS_MODULE,
};

static struct config_item_type spaces_type = {
    .ct_group_ops = &spaces_ops,
    .ct_owner = THIS_MODULE,
};

static struct config_item_type space_type = {
    .ct_item_ops = &space_ops,
    .ct_owner = THIS_MODULE,
};

static struct config_item_type comms_type = {
    .ct_group_ops = &comms_ops,
    .ct_owner = THIS_MODULE,
};

static struct config_item_type comm_type = {
    .ct_item_ops = &comm_ops,
    .ct_attrs = comm_attrs,
    .ct_owner = THIS_MODULE,
};

static struct config_item_type nodes_type = {
    .ct_group_ops = &nodes_ops,
    .ct_owner = THIS_MODULE,
};

static struct config_item_type node_type = {
    .ct_item_ops = &node_ops,
    .ct_attrs = node_attrs,
    .ct_owner = THIS_MODULE,
};

static struct dlm_cluster *config_item_to_cluster(struct config_item *i)
{
    return i ? container_of(to_config_group(i), struct dlm_cluster, group) :
           NULL;
}

static struct dlm_space *config_item_to_space(struct config_item *i)
{
    return i ? container_of(to_config_group(i), struct dlm_space, group) :
           NULL;
}

static struct dlm_comm *config_item_to_comm(struct config_item *i)
{
    return i ? container_of(i, struct dlm_comm, item) : NULL;
}

static struct dlm_node *config_item_to_node(struct config_item *i)
{
    return i ? container_of(i, struct dlm_node, item) : NULL;
}

static struct config_group *make_cluster(struct config_group *g,
                     const char *name)
{
    struct dlm_cluster *cl = NULL;
    struct dlm_spaces *sps = NULL;
    struct dlm_comms *cms = NULL;
    void *gps = NULL;

    cl = kzalloc(sizeof(struct dlm_cluster), GFP_NOFS);
    gps = kcalloc(3, sizeof(struct config_group *), GFP_NOFS);
    sps = kzalloc(sizeof(struct dlm_spaces), GFP_NOFS);
    cms = kzalloc(sizeof(struct dlm_comms), GFP_NOFS);

    if (!cl || !gps || !sps || !cms)
        goto fail;

    config_group_init_type_name(&cl->group, name, &cluster_type);
    config_group_init_type_name(&sps->ss_group, "spaces", &spaces_type);
    config_group_init_type_name(&cms->cs_group, "comms", &comms_type);

    cl->group.default_groups = gps;
    cl->group.default_groups[0] = &sps->ss_group;
    cl->group.default_groups[1] = &cms->cs_group;
    cl->group.default_groups[2] = NULL;

    cl->cl_tcp_port = dlm_config.ci_tcp_port;
    cl->cl_buffer_size = dlm_config.ci_buffer_size;
    cl->cl_rsbtbl_size = dlm_config.ci_rsbtbl_size;
    cl->cl_recover_timer = dlm_config.ci_recover_timer;
    cl->cl_toss_secs = dlm_config.ci_toss_secs;
    cl->cl_scan_secs = dlm_config.ci_scan_secs;
    cl->cl_log_debug = dlm_config.ci_log_debug;
    cl->cl_protocol = dlm_config.ci_protocol;
    cl->cl_timewarn_cs = dlm_config.ci_timewarn_cs;
    cl->cl_waitwarn_us = dlm_config.ci_waitwarn_us;
    cl->cl_new_rsb_count = dlm_config.ci_new_rsb_count;
    cl->cl_recover_callbacks = dlm_config.ci_recover_callbacks;
    memcpy(cl->cl_cluster_name, dlm_config.ci_cluster_name,
           DLM_LOCKSPACE_LEN);

    space_list = &sps->ss_group;
    comm_list = &cms->cs_group;
    return &cl->group;

 fail:
    kfree(cl);
    kfree(gps);
    kfree(sps);
    kfree(cms);
    return ERR_PTR(-ENOMEM);
}

static void drop_cluster(struct config_group *g, struct config_item *i)
{
    struct dlm_cluster *cl = config_item_to_cluster(i);
    struct config_item *tmp;
    int j;

    for (j = 0; cl->group.default_groups[j]; j++) {
        tmp = &cl->group.default_groups[j]->cg_item;
        cl->group.default_groups[j] = NULL;
        config_item_put(tmp);
    }

    space_list = NULL;
    comm_list = NULL;

    config_item_put(i);
}

static void release_cluster(struct config_item *i)
{
    struct dlm_cluster *cl = config_item_to_cluster(i);
    kfree(cl->group.default_groups);
    kfree(cl);
}

static struct config_group *make_space(struct config_group *g, const char *name)
{
    struct dlm_space *sp = NULL;
    struct dlm_nodes *nds = NULL;
    void *gps = NULL;

    sp = kzalloc(sizeof(struct dlm_space), GFP_NOFS);
    gps = kcalloc(2, sizeof(struct config_group *), GFP_NOFS);
    nds = kzalloc(sizeof(struct dlm_nodes), GFP_NOFS);

    if (!sp || !gps || !nds)
        goto fail;

    config_group_init_type_name(&sp->group, name, &space_type);
    config_group_init_type_name(&nds->ns_group, "nodes", &nodes_type);

    sp->group.default_groups = gps;
    sp->group.default_groups[0] = &nds->ns_group;
    sp->group.default_groups[1] = NULL;

    INIT_LIST_HEAD(&sp->members);
    mutex_init(&sp->members_lock);
    sp->members_count = 0;
    return &sp->group;

 fail:
    kfree(sp);
    kfree(gps);
    kfree(nds);
    return ERR_PTR(-ENOMEM);
}

static void drop_space(struct config_group *g, struct config_item *i)
{
    struct dlm_space *sp = config_item_to_space(i);
    struct config_item *tmp;
    int j;

    /* assert list_empty(&sp->members) */

    for (j = 0; sp->group.default_groups[j]; j++) {
        tmp = &sp->group.default_groups[j]->cg_item;
        sp->group.default_groups[j] = NULL;
        config_item_put(tmp);
    }

    config_item_put(i);
}

static void release_space(struct config_item *i)
{
    struct dlm_space *sp = config_item_to_space(i);
    kfree(sp->group.default_groups);
    kfree(sp);
}

static struct config_item *make_comm(struct config_group *g, const char *name)
{
    struct dlm_comm *cm;

    cm = kzalloc(sizeof(struct dlm_comm), GFP_NOFS);
    if (!cm)
        return ERR_PTR(-ENOMEM);

    config_item_init_type_name(&cm->item, name, &comm_type);

    cm->seq = dlm_comm_count++;
    if (!cm->seq)
        cm->seq = dlm_comm_count++;

    cm->nodeid = -1;
    cm->local = 0;
    cm->addr_count = 0;
    return &cm->item;
}

static void drop_comm(struct config_group *g, struct config_item *i)
{
    struct dlm_comm *cm = config_item_to_comm(i);
    if (local_comm == cm)
        local_comm = NULL;
    dlm_lowcomms_close(cm->nodeid);
    while (cm->addr_count--)
        kfree(cm->addr[cm->addr_count]);
    config_item_put(i);
}

static void release_comm(struct config_item *i)
{
    struct dlm_comm *cm = config_item_to_comm(i);
    kfree(cm);
}

static struct config_item *make_node(struct config_group *g, const char *name)
{
    struct dlm_space *sp = config_item_to_space(g->cg_item.ci_parent);
    struct dlm_node *nd;

    nd = kzalloc(sizeof(struct dlm_node), GFP_NOFS);
    if (!nd)
        return ERR_PTR(-ENOMEM);

    config_item_init_type_name(&nd->item, name, &node_type);
    nd->nodeid = -1;
    nd->weight = 1;  /* default weight of 1 if none is set */
    nd->new = 1;     /* set to 0 once it's been read by dlm_nodeid_list() */

    mutex_lock(&sp->members_lock);
    list_add(&nd->list, &sp->members);
    sp->members_count++;
    mutex_unlock(&sp->members_lock);

    return &nd->item;
}

static void drop_node(struct config_group *g, struct config_item *i)
{
    struct dlm_space *sp = config_item_to_space(g->cg_item.ci_parent);
    struct dlm_node *nd = config_item_to_node(i);

    mutex_lock(&sp->members_lock);
    list_del(&nd->list);
    sp->members_count--;
    mutex_unlock(&sp->members_lock);

    config_item_put(i);
}

static void release_node(struct config_item *i)
{
    struct dlm_node *nd = config_item_to_node(i);
    kfree(nd);
}

static struct dlm_clusters clusters_root = {
    .subsys = {
        .su_group = {
            .cg_item = {
                .ci_namebuf = "dlm",
                .ci_type = &clusters_type,
            },
        },
    },
};

int __init dlm_config_init(void)
{
    config_group_init(&clusters_root.subsys.su_group);
    mutex_init(&clusters_root.subsys.su_mutex);
    return configfs_register_subsystem(&clusters_root.subsys);
}

void dlm_config_exit(void)
{
    configfs_unregister_subsystem(&clusters_root.subsys);
}

/*
 * Functions for user space to read/write attributes
 */

static ssize_t show_cluster(struct config_item *i, struct configfs_attribute *a,
                char *buf)
{
    struct dlm_cluster *cl = config_item_to_cluster(i);
    struct cluster_attribute *cla =
            container_of(a, struct cluster_attribute, attr);
    return cla->show ? cla->show(cl, buf) : 0;
}

static ssize_t store_cluster(struct config_item *i,
                 struct configfs_attribute *a,
                 const char *buf, size_t len)
{
    struct dlm_cluster *cl = config_item_to_cluster(i);
    struct cluster_attribute *cla =
        container_of(a, struct cluster_attribute, attr);
    return cla->store ? cla->store(cl, buf, len) : -EINVAL;
}

static ssize_t show_comm(struct config_item *i, struct configfs_attribute *a,
             char *buf)
{
    struct dlm_comm *cm = config_item_to_comm(i);
    struct comm_attribute *cma =
            container_of(a, struct comm_attribute, attr);
    return cma->show ? cma->show(cm, buf) : 0;
}

static ssize_t store_comm(struct config_item *i, struct configfs_attribute *a,
              const char *buf, size_t len)
{
    struct dlm_comm *cm = config_item_to_comm(i);
    struct comm_attribute *cma =
        container_of(a, struct comm_attribute, attr);
    return cma->store ? cma->store(cm, buf, len) : -EINVAL;
}

static ssize_t comm_nodeid_read(struct dlm_comm *cm, char *buf)
{
    return sprintf(buf, "%d\n", cm->nodeid);
}

static ssize_t comm_nodeid_write(struct dlm_comm *cm, const char *buf,
                 size_t len)
{
    cm->nodeid = simple_strtol(buf, NULL, 0);
    return len;
}

static ssize_t comm_local_read(struct dlm_comm *cm, char *buf)
{
    return sprintf(buf, "%d\n", cm->local);
}

static ssize_t comm_local_write(struct dlm_comm *cm, const char *buf,
                size_t len)
{
    cm->local= simple_strtol(buf, NULL, 0);
    if (cm->local && !local_comm)
        local_comm = cm;
    return len;
}

static ssize_t comm_addr_write(struct dlm_comm *cm, const char *buf, size_t len)
{
    struct sockaddr_storage *addr;
    int rv;

    if (len != sizeof(struct sockaddr_storage))
        return -EINVAL;

    if (cm->addr_count >= DLM_MAX_ADDR_COUNT)
        return -ENOSPC;

    addr = kzalloc(sizeof(*addr), GFP_NOFS);
    if (!addr)
        return -ENOMEM;

    memcpy(addr, buf, len);

    rv = dlm_lowcomms_addr(cm->nodeid, addr, len);
    if (rv) {
        kfree(addr);
        return rv;
    }

    cm->addr[cm->addr_count++] = addr;
    return len;
}

static ssize_t comm_addr_list_read(struct dlm_comm *cm, char *buf)
{
    ssize_t s;
    ssize_t allowance;
    int i;
    struct sockaddr_storage *addr;
    struct sockaddr_in *addr_in;
    struct sockaddr_in6 *addr_in6;
    
    /* Taken from ip6_addr_string() defined in lib/vsprintf.c */
    char buf0[sizeof("AF_INET6  xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255\n")];
    

    /* Derived from SIMPLE_ATTR_SIZE of fs/configfs/file.c */
    allowance = 4096;
    buf[0] = '\0';

    for (i = 0; i < cm->addr_count; i++) {
        addr = cm->addr[i];

        switch(addr->ss_family) {
        case AF_INET:
            addr_in = (struct sockaddr_in *)addr;
            s = sprintf(buf0, "AF_INET  %pI4\n", &addr_in->sin_addr.s_addr);
            break;
        case AF_INET6:
            addr_in6 = (struct sockaddr_in6 *)addr;
            s = sprintf(buf0, "AF_INET6 %pI6\n", &addr_in6->sin6_addr);
            break;
        default:
            s = sprintf(buf0, "%s\n", "<UNKNOWN>");
            break;
        }
        allowance -= s;
        if (allowance >= 0)
            strcat(buf, buf0);
        else {
            allowance += s;
            break;
        }
    }
    return 4096 - allowance;
}

static ssize_t show_node(struct config_item *i, struct configfs_attribute *a,
             char *buf)
{
    struct dlm_node *nd = config_item_to_node(i);
    struct node_attribute *nda =
            container_of(a, struct node_attribute, attr);
    return nda->show ? nda->show(nd, buf) : 0;
}

static ssize_t store_node(struct config_item *i, struct configfs_attribute *a,
              const char *buf, size_t len)
{
    struct dlm_node *nd = config_item_to_node(i);
    struct node_attribute *nda =
        container_of(a, struct node_attribute, attr);
    return nda->store ? nda->store(nd, buf, len) : -EINVAL;
}

static ssize_t node_nodeid_read(struct dlm_node *nd, char *buf)
{
    return sprintf(buf, "%d\n", nd->nodeid);
}

static ssize_t node_nodeid_write(struct dlm_node *nd, const char *buf,
                 size_t len)
{
    uint32_t seq = 0;
    nd->nodeid = simple_strtol(buf, NULL, 0);
    dlm_comm_seq(nd->nodeid, &seq);
    nd->comm_seq = seq;
    return len;
}

static ssize_t node_weight_read(struct dlm_node *nd, char *buf)
{
    return sprintf(buf, "%d\n", nd->weight);
}

static ssize_t node_weight_write(struct dlm_node *nd, const char *buf,
                 size_t len)
{
    nd->weight = simple_strtol(buf, NULL, 0);
    return len;
}

/*
 * Functions for the dlm to get the info that's been configured
 */

static struct dlm_space *get_space(char *name)
{
    struct config_item *i;

    if (!space_list)
        return NULL;

    mutex_lock(&space_list->cg_subsys->su_mutex);
    i = config_group_find_item(space_list, name);
    mutex_unlock(&space_list->cg_subsys->su_mutex);

    return config_item_to_space(i);
}

static void put_space(struct dlm_space *sp)
{
    config_item_put(&sp->group.cg_item);
}

static struct dlm_comm *get_comm(int nodeid)
{
    struct config_item *i;
    struct dlm_comm *cm = NULL;
    int found = 0;

    if (!comm_list)
        return NULL;

    mutex_lock(&clusters_root.subsys.su_mutex);

    list_for_each_entry(i, &comm_list->cg_children, ci_entry) {
        cm = config_item_to_comm(i);

        if (cm->nodeid != nodeid)
            continue;
        found = 1;
        config_item_get(i);
        break;
    }
    mutex_unlock(&clusters_root.subsys.su_mutex);

    if (!found)
        cm = NULL;
    return cm;
}

static void put_comm(struct dlm_comm *cm)
{
    config_item_put(&cm->item);
}

/* caller must free mem */
int dlm_config_nodes(char *lsname, struct dlm_config_node **nodes_out,
             int *count_out)
{
    struct dlm_space *sp;
    struct dlm_node *nd;
    struct dlm_config_node *nodes, *node;
    int rv, count;

    sp = get_space(lsname);
    if (!sp)
        return -EEXIST;

    mutex_lock(&sp->members_lock);
    if (!sp->members_count) {
        rv = -EINVAL;
        printk(KERN_ERR "dlm: zero members_count\n");
        goto out;
    }

    count = sp->members_count;

    nodes = kcalloc(count, sizeof(struct dlm_config_node), GFP_NOFS);
    if (!nodes) {
        rv = -ENOMEM;
        goto out;
    }

    node = nodes;
    list_for_each_entry(nd, &sp->members, list) {
        node->nodeid = nd->nodeid;
        node->weight = nd->weight;
        node->new = nd->new;
        node->comm_seq = nd->comm_seq;
        node++;

        nd->new = 0;
    }

    *count_out = count;
    *nodes_out = nodes;
    rv = 0;
 out:
    mutex_unlock(&sp->members_lock);
    put_space(sp);
    return rv;
}

int dlm_comm_seq(int nodeid, uint32_t *seq)
{
    struct dlm_comm *cm = get_comm(nodeid);
    if (!cm)
        return -EEXIST;
    *seq = cm->seq;
    put_comm(cm);
    return 0;
}

int dlm_our_nodeid(void)
{
    return local_comm ? local_comm->nodeid : 0;
}

/* num 0 is first addr, num 1 is second addr */
int dlm_our_addr(struct sockaddr_storage *addr, int num)
{
    if (!local_comm)
        return -1;
    if (num + 1 > local_comm->addr_count)
        return -1;
    memcpy(addr, local_comm->addr[num], sizeof(*addr));
    return 0;
}

/* Config file defaults */
#define DEFAULT_TCP_PORT       21064
#define DEFAULT_BUFFER_SIZE     4096
#define DEFAULT_RSBTBL_SIZE     1024
#define DEFAULT_RECOVER_TIMER      5
#define DEFAULT_TOSS_SECS         10
#define DEFAULT_SCAN_SECS          5
#define DEFAULT_LOG_DEBUG          0
#define DEFAULT_PROTOCOL           0
#define DEFAULT_TIMEWARN_CS      500 /* 5 sec = 500 centiseconds */
#define DEFAULT_WAITWARN_US    0
#define DEFAULT_NEW_RSB_COUNT    128
#define DEFAULT_RECOVER_CALLBACKS  0
#define DEFAULT_CLUSTER_NAME      ""

struct dlm_config_info dlm_config = {
    .ci_tcp_port = DEFAULT_TCP_PORT,
    .ci_buffer_size = DEFAULT_BUFFER_SIZE,
    .ci_rsbtbl_size = DEFAULT_RSBTBL_SIZE,
    .ci_recover_timer = DEFAULT_RECOVER_TIMER,
    .ci_toss_secs = DEFAULT_TOSS_SECS,
    .ci_scan_secs = DEFAULT_SCAN_SECS,
    .ci_log_debug = DEFAULT_LOG_DEBUG,
    .ci_protocol = DEFAULT_PROTOCOL,
    .ci_timewarn_cs = DEFAULT_TIMEWARN_CS,
    .ci_waitwarn_us = DEFAULT_WAITWARN_US,
    .ci_new_rsb_count = DEFAULT_NEW_RSB_COUNT,
    .ci_recover_callbacks = DEFAULT_RECOVER_CALLBACKS,
    .ci_cluster_name = DEFAULT_CLUSTER_NAME
};