dm-uevent.c

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/*
 * Device Mapper Uevent Support (dm-uevent)
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright IBM Corporation, 2007
 *  Author: Mike Anderson <[email protected]>
 */
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/kobject.h>
#include <linux/dm-ioctl.h>
#include <linux/export.h>

#include "dm.h"
#include "dm-uevent.h"

#define DM_MSG_PREFIX "uevent"

static const struct {
    enum dm_uevent_type type;
    enum kobject_action action;
    char *name;
} _dm_uevent_type_names[] = {
    {DM_UEVENT_PATH_FAILED, KOBJ_CHANGE, "PATH_FAILED"},
    {DM_UEVENT_PATH_REINSTATED, KOBJ_CHANGE, "PATH_REINSTATED"},
};

static struct kmem_cache *_dm_event_cache;

struct dm_uevent {
    struct mapped_device *md;
    enum kobject_action action;
    struct kobj_uevent_env ku_env;
    struct list_head elist;
    char name[DM_NAME_LEN];
    char uuid[DM_UUID_LEN];
};

static void dm_uevent_free(struct dm_uevent *event)
{
    kmem_cache_free(_dm_event_cache, event);
}

static struct dm_uevent *dm_uevent_alloc(struct mapped_device *md)
{
    struct dm_uevent *event;

    event = kmem_cache_zalloc(_dm_event_cache, GFP_ATOMIC);
    if (!event)
        return NULL;

    INIT_LIST_HEAD(&event->elist);
    event->md = md;

    return event;
}

static struct dm_uevent *dm_build_path_uevent(struct mapped_device *md,
                          struct dm_target *ti,
                          enum kobject_action action,
                          const char *dm_action,
                          const char *path,
                          unsigned nr_valid_paths)
{
    struct dm_uevent *event;

    event = dm_uevent_alloc(md);
    if (!event) {
        DMERR("%s: dm_uevent_alloc() failed", __func__);
        goto err_nomem;
    }

    event->action = action;

    if (add_uevent_var(&event->ku_env, "DM_TARGET=%s", ti->type->name)) {
        DMERR("%s: add_uevent_var() for DM_TARGET failed",
              __func__);
        goto err_add;
    }

    if (add_uevent_var(&event->ku_env, "DM_ACTION=%s", dm_action)) {
        DMERR("%s: add_uevent_var() for DM_ACTION failed",
              __func__);
        goto err_add;
    }

    if (add_uevent_var(&event->ku_env, "DM_SEQNUM=%u",
               dm_next_uevent_seq(md))) {
        DMERR("%s: add_uevent_var() for DM_SEQNUM failed",
              __func__);
        goto err_add;
    }

    if (add_uevent_var(&event->ku_env, "DM_PATH=%s", path)) {
        DMERR("%s: add_uevent_var() for DM_PATH failed", __func__);
        goto err_add;
    }

    if (add_uevent_var(&event->ku_env, "DM_NR_VALID_PATHS=%d",
               nr_valid_paths)) {
        DMERR("%s: add_uevent_var() for DM_NR_VALID_PATHS failed",
              __func__);
        goto err_add;
    }

    return event;

err_add:
    dm_uevent_free(event);
err_nomem:
    return ERR_PTR(-ENOMEM);
}

void dm_send_uevents(struct list_head *events, struct kobject *kobj)
{
    int r;
    struct dm_uevent *event, *next;

    list_for_each_entry_safe(event, next, events, elist) {
        list_del_init(&event->elist);

        /*
         * When a device is being removed this copy fails and we
         * discard these unsent events.
         */
        if (dm_copy_name_and_uuid(event->md, event->name,
                      event->uuid)) {
            DMINFO("%s: skipping sending uevent for lost device",
                   __func__);
            goto uevent_free;
        }

        if (add_uevent_var(&event->ku_env, "DM_NAME=%s", event->name)) {
            DMERR("%s: add_uevent_var() for DM_NAME failed",
                  __func__);
            goto uevent_free;
        }

        if (add_uevent_var(&event->ku_env, "DM_UUID=%s", event->uuid)) {
            DMERR("%s: add_uevent_var() for DM_UUID failed",
                  __func__);
            goto uevent_free;
        }

        r = kobject_uevent_env(kobj, event->action, event->ku_env.envp);
        if (r)
            DMERR("%s: kobject_uevent_env failed", __func__);
uevent_free:
        dm_uevent_free(event);
    }
}
EXPORT_SYMBOL_GPL(dm_send_uevents);

void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
           const char *path, unsigned nr_valid_paths)
{
    struct mapped_device *md = dm_table_get_md(ti->table);
    struct dm_uevent *event;

    if (event_type >= ARRAY_SIZE(_dm_uevent_type_names)) {
        DMERR("%s: Invalid event_type %d", __func__, event_type);
        return;
    }

    event = dm_build_path_uevent(md, ti,
                     _dm_uevent_type_names[event_type].action,
                     _dm_uevent_type_names[event_type].name,
                     path, nr_valid_paths);
    if (IS_ERR(event))
        return;

    dm_uevent_add(md, &event->elist);
}
EXPORT_SYMBOL_GPL(dm_path_uevent);

int dm_uevent_init(void)
{
    _dm_event_cache = KMEM_CACHE(dm_uevent, 0);
    if (!_dm_event_cache)
        return -ENOMEM;

    DMINFO("version 1.0.3");

    return 0;
}

void dm_uevent_exit(void)
{
    kmem_cache_destroy(_dm_event_cache);
}