drivers/md/dm-uevent.c

   1 /*
   2  * Device Mapper Uevent Support (dm-uevent)
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the
   6  * Free Software Foundation; either version 2 of the License, or (at your
   7  * option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright IBM Corporation, 2007
  19  *      Author: Mike Anderson <andmike@linux.vnet.ibm.com>
  20  */
  21 #include <linux/list.h>
  22 #include <linux/slab.h>
  23 #include <linux/kobject.h>
  24 #include <linux/dm-ioctl.h>
  25
  26 #include "dm.h"
  27 #include "dm-uevent.h"
  28
  29 #define DM_MSG_PREFIX "uevent"
  30
  31 static const struct {
  32         enum dm_uevent_type type;
  33         enum kobject_action action;
  34         char *name;
  35 } _dm_uevent_type_names[] = {
  36         {DM_UEVENT_PATH_FAILED, KOBJ_CHANGE, "PATH_FAILED"},
  37         {DM_UEVENT_PATH_REINSTATED, KOBJ_CHANGE, "PATH_REINSTATED"},
  38 };
  39
  40 static struct kmem_cache *_dm_event_cache;
  41
  42 struct dm_uevent {
  43         struct mapped_device *md;
  44         enum kobject_action action;
  45         struct kobj_uevent_env ku_env;
  46         struct list_head elist;
  47         char name[DM_NAME_LEN];
  48         char uuid[DM_UUID_LEN];
  49 };
  50
  51 static void dm_uevent_free(struct dm_uevent *event)
  52 {
  53         kmem_cache_free(_dm_event_cache, event);
  54 }
  55
  56 static struct dm_uevent *dm_uevent_alloc(struct mapped_device *md)
  57 {
  58         struct dm_uevent *event;
  59
  60         event = kmem_cache_zalloc(_dm_event_cache, GFP_ATOMIC);
  61         if (!event)
  62                 return NULL;
  63
  64         INIT_LIST_HEAD(&event->elist);
  65         event->md = md;
  66
  67         return event;
  68 }
  69
  70 static struct dm_uevent *dm_build_path_uevent(struct mapped_device *md,
  71                                               struct dm_target *ti,
  72                                               enum kobject_action action,
  73                                               const char *dm_action,
  74                                               const char *path,
  75                                               unsigned nr_valid_paths)
  76 {
  77         struct dm_uevent *event;
  78
  79         event = dm_uevent_alloc(md);
  80         if (!event) {
  81                 DMERR("%s: dm_uevent_alloc() failed", __func__);
  82                 goto err_nomem;
  83         }
  84
  85         event->action = action;
  86
  87         if (add_uevent_var(&event->ku_env, "DM_TARGET=%s", ti->type->name)) {
  88                 DMERR("%s: add_uevent_var() for DM_TARGET failed",
  89                       __func__);
  90                 goto err_add;
  91         }
  92
  93         if (add_uevent_var(&event->ku_env, "DM_ACTION=%s", dm_action)) {
  94                 DMERR("%s: add_uevent_var() for DM_ACTION failed",
  95                       __func__);
  96                 goto err_add;
  97         }
  98
  99         if (add_uevent_var(&event->ku_env, "DM_SEQNUM=%u",
 100                            dm_next_uevent_seq(md))) {
 101                 DMERR("%s: add_uevent_var() for DM_SEQNUM failed",
 102                       __func__);
 103                 goto err_add;
 104         }
 105
 106         if (add_uevent_var(&event->ku_env, "DM_PATH=%s", path)) {
 107                 DMERR("%s: add_uevent_var() for DM_PATH failed", __func__);
 108                 goto err_add;
 109         }
 110
 111         if (add_uevent_var(&event->ku_env, "DM_NR_VALID_PATHS=%d",
 112                            nr_valid_paths)) {
 113                 DMERR("%s: add_uevent_var() for DM_NR_VALID_PATHS failed",
 114                       __func__);
 115                 goto err_add;
 116         }
 117
 118         return event;
 119
 120 err_add:
 121         dm_uevent_free(event);
 122 err_nomem:
 123         return ERR_PTR(-ENOMEM);
 124 }
 125
 126 /**
 127  * dm_send_uevents - send uevents for given list
 128  *
 129  * @events:     list of events to send
 130  * @kobj:       kobject generating event
 131  *
 132  */
 133 void dm_send_uevents(struct list_head *events, struct kobject *kobj)
 134 {
 135         int r;
 136         struct dm_uevent *event, *next;
 137
 138         list_for_each_entry_safe(event, next, events, elist) {
 139                 list_del_init(&event->elist);
 140
 141                 /*
 142                  * When a device is being removed this copy fails and we
 143                  * discard these unsent events.
 144                  */
 145                 if (dm_copy_name_and_uuid(event->md, event->name,
 146                                           event->uuid)) {
 147                         DMINFO("%s: skipping sending uevent for lost device",
 148                                __func__);
 149                         goto uevent_free;
 150                 }
 151
 152                 if (add_uevent_var(&event->ku_env, "DM_NAME=%s", event->name)) {
 153                         DMERR("%s: add_uevent_var() for DM_NAME failed",
 154                               __func__);
 155                         goto uevent_free;
 156                 }
 157
 158                 if (add_uevent_var(&event->ku_env, "DM_UUID=%s", event->uuid)) {
 159                         DMERR("%s: add_uevent_var() for DM_UUID failed",
 160                               __func__);
 161                         goto uevent_free;
 162                 }
 163
 164                 r = kobject_uevent_env(kobj, event->action, event->ku_env.envp);
 165                 if (r)
 166                         DMERR("%s: kobject_uevent_env failed", __func__);
 167 uevent_free:
 168                 dm_uevent_free(event);
 169         }
 170 }
 171 EXPORT_SYMBOL_GPL(dm_send_uevents);
 172
 173 /**
 174  * dm_path_uevent - called to create a new path event and queue it
 175  *
 176  * @event_type: path event type enum
 177  * @ti:                 pointer to a dm_target
 178  * @path:               string containing pathname
 179  * @nr_valid_paths:     number of valid paths remaining
 180  *
 181  */
 182 void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
 183                    const char *path, unsigned nr_valid_paths)
 184 {
 185         struct mapped_device *md = dm_table_get_md(ti->table);
 186         struct dm_uevent *event;
 187
 188         if (event_type >= ARRAY_SIZE(_dm_uevent_type_names)) {
 189                 DMERR("%s: Invalid event_type %d", __func__, event_type);
 190                 return;
 191         }
 192
 193         event = dm_build_path_uevent(md, ti,
 194                                      _dm_uevent_type_names[event_type].action,
 195                                      _dm_uevent_type_names[event_type].name,
 196                                      path, nr_valid_paths);
 197         if (IS_ERR(event))
 198                 return;
 199
 200         dm_uevent_add(md, &event->elist);
 201 }
 202 EXPORT_SYMBOL_GPL(dm_path_uevent);
 203
 204 int dm_uevent_init(void)
 205 {
 206         _dm_event_cache = KMEM_CACHE(dm_uevent, 0);
 207         if (!_dm_event_cache)
 208                 return -ENOMEM;
 209
 210         DMINFO("version 1.0.3");
 211
 212         return 0;
 213 }
 214
 215 void dm_uevent_exit(void)
 216 {
 217         kmem_cache_destroy(_dm_event_cache);
 218 }