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dm-uevent.c

/*
 * 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 <andmike@linux.vnet.ibm.com>
 */
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/kobject.h>
#include <linux/dm-ioctl.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", __FUNCTION__);
            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",
                  __FUNCTION__);
            goto err_add;
      }

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

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

      return event;

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

/**
 * dm_send_uevents - send uevents for given list
 *
 * @events: list of events to send
 * @kobj:   kobject generating event
 *
 */
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);

            /*
             * Need to call dm_copy_name_and_uuid from here for now.
             * Context of previous var adds and locking used for
             * hash_cell not compatable.
             */
            if (dm_copy_name_and_uuid(event->md, event->name,
                                event->uuid)) {
                  DMERR("%s: dm_copy_name_and_uuid() failed",
                        __FUNCTION__);
                  goto uevent_free;
            }

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

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

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

/**
 * dm_path_uevent - called to create a new path event and queue it
 *
 * @event_type:   path event type enum
 * @ti:                 pointer to a dm_target
 * @path:         string containing pathname
 * @nr_valid_paths:     number of valid paths remaining
 *
 */
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", __FUNCTION__, event_type);
            goto out;
      }

      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))
            goto out;

      dm_uevent_add(md, &event->elist);

out:
      dm_put(md);
}
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);
}

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