drivers/md/dm-uevent.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Device Mapper Uevent Support (dm-uevent)
   4  *
   5  * Copyright IBM Corporation, 2007
   6  *      Author: Mike Anderson <andmike@linux.vnet.ibm.com>
   7  */
   8 #include <linux/list.h>
   9 #include <linux/slab.h>
  10 #include <linux/kobject.h>
  11 #include <linux/dm-ioctl.h>
  12 #include <linux/export.h>
  13
  14 #include "dm.h"
  15 #include "dm-uevent.h"
  16
  17 #define DM_MSG_PREFIX "uevent"
  18
  19 static const struct {
  20         enum dm_uevent_type type;
  21         enum kobject_action action;
  22         char *name;
  23 } _dm_uevent_type_names[] = {
  24         {DM_UEVENT_PATH_FAILED, KOBJ_CHANGE, "PATH_FAILED"},
  25         {DM_UEVENT_PATH_REINSTATED, KOBJ_CHANGE, "PATH_REINSTATED"},
  26 };
  27
  28 static struct kmem_cache *_dm_event_cache;
  29
  30 struct dm_uevent {
  31         struct mapped_device *md;
  32         enum kobject_action action;
  33         struct kobj_uevent_env ku_env;
  34         struct list_head elist;
  35         char name[DM_NAME_LEN];
  36         char uuid[DM_UUID_LEN];
  37 };
  38
  39 static void dm_uevent_free(struct dm_uevent *event)
  40 {
  41         kmem_cache_free(_dm_event_cache, event);
  42 }
  43
  44 static struct dm_uevent *dm_uevent_alloc(struct mapped_device *md)
  45 {
  46         struct dm_uevent *event;
  47
  48         event = kmem_cache_zalloc(_dm_event_cache, GFP_ATOMIC);
  49         if (!event)
  50                 return NULL;
  51
  52         INIT_LIST_HEAD(&event->elist);
  53         event->md = md;
  54
  55         return event;
  56 }
  57
  58 static struct dm_uevent *dm_build_path_uevent(struct mapped_device *md,
  59                                               struct dm_target *ti,
  60                                               enum kobject_action action,
  61                                               const char *dm_action,
  62                                               const char *path,
  63                                               unsigned int nr_valid_paths)
  64 {
  65         struct dm_uevent *event;
  66
  67         event = dm_uevent_alloc(md);
  68         if (!event) {
  69                 DMERR("%s: dm_uevent_alloc() failed", __func__);
  70                 goto err_nomem;
  71         }
  72
  73         event->action = action;
  74
  75         if (add_uevent_var(&event->ku_env, "DM_TARGET=%s", ti->type->name)) {
  76                 DMERR("%s: add_uevent_var() for DM_TARGET failed",
  77                       __func__);
  78                 goto err_add;
  79         }
  80
  81         if (add_uevent_var(&event->ku_env, "DM_ACTION=%s", dm_action)) {
  82                 DMERR("%s: add_uevent_var() for DM_ACTION failed",
  83                       __func__);
  84                 goto err_add;
  85         }
  86
  87         if (add_uevent_var(&event->ku_env, "DM_SEQNUM=%u",
  88                            dm_next_uevent_seq(md))) {
  89                 DMERR("%s: add_uevent_var() for DM_SEQNUM failed",
  90                       __func__);
  91                 goto err_add;
  92         }
  93
  94         if (add_uevent_var(&event->ku_env, "DM_PATH=%s", path)) {
  95                 DMERR("%s: add_uevent_var() for DM_PATH failed", __func__);
  96                 goto err_add;
  97         }
  98
  99         if (add_uevent_var(&event->ku_env, "DM_NR_VALID_PATHS=%d",
 100                            nr_valid_paths)) {
 101                 DMERR("%s: add_uevent_var() for DM_NR_VALID_PATHS failed",
 102                       __func__);
 103                 goto err_add;
 104         }
 105
 106         return event;
 107
 108 err_add:
 109         dm_uevent_free(event);
 110 err_nomem:
 111         return ERR_PTR(-ENOMEM);
 112 }
 113
 114 /**
 115  * dm_send_uevents - send uevents for given list
 116  *
 117  * @events:     list of events to send
 118  * @kobj:       kobject generating event
 119  *
 120  */
 121 void dm_send_uevents(struct list_head *events, struct kobject *kobj)
 122 {
 123         int r;
 124         struct dm_uevent *event, *next;
 125
 126         list_for_each_entry_safe(event, next, events, elist) {
 127                 list_del_init(&event->elist);
 128
 129                 /*
 130                  * When a device is being removed this copy fails and we
 131                  * discard these unsent events.
 132                  */
 133                 if (dm_copy_name_and_uuid(event->md, event->name,
 134                                           event->uuid)) {
 135                         DMINFO("%s: skipping sending uevent for lost device",
 136                                __func__);
 137                         goto uevent_free;
 138                 }
 139
 140                 if (add_uevent_var(&event->ku_env, "DM_NAME=%s", event->name)) {
 141                         DMERR("%s: add_uevent_var() for DM_NAME failed",
 142                               __func__);
 143                         goto uevent_free;
 144                 }
 145
 146                 if (add_uevent_var(&event->ku_env, "DM_UUID=%s", event->uuid)) {
 147                         DMERR("%s: add_uevent_var() for DM_UUID failed",
 148                               __func__);
 149                         goto uevent_free;
 150                 }
 151
 152                 r = kobject_uevent_env(kobj, event->action, event->ku_env.envp);
 153                 if (r)
 154                         DMERR("%s: kobject_uevent_env failed", __func__);
 155 uevent_free:
 156                 dm_uevent_free(event);
 157         }
 158 }
 159 EXPORT_SYMBOL_GPL(dm_send_uevents);
 160
 161 /**
 162  * dm_path_uevent - called to create a new path event and queue it
 163  *
 164  * @event_type: path event type enum
 165  * @ti:                 pointer to a dm_target
 166  * @path:               string containing pathname
 167  * @nr_valid_paths:     number of valid paths remaining
 168  *
 169  */
 170 void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
 171                    const char *path, unsigned int nr_valid_paths)
 172 {
 173         struct mapped_device *md = dm_table_get_md(ti->table);
 174         struct dm_uevent *event;
 175
 176         if (event_type >= ARRAY_SIZE(_dm_uevent_type_names)) {
 177                 DMERR("%s: Invalid event_type %d", __func__, event_type);
 178                 return;
 179         }
 180
 181         event = dm_build_path_uevent(md, ti,
 182                                      _dm_uevent_type_names[event_type].action,
 183                                      _dm_uevent_type_names[event_type].name,
 184                                      path, nr_valid_paths);
 185         if (IS_ERR(event))
 186                 return;
 187
 188         dm_uevent_add(md, &event->elist);
 189 }
 190 EXPORT_SYMBOL_GPL(dm_path_uevent);
 191
 192 int dm_uevent_init(void)
 193 {
 194         _dm_event_cache = KMEM_CACHE(dm_uevent, 0);
 195         if (!_dm_event_cache)
 196                 return -ENOMEM;
 197
 198         DMINFO("version 1.0.3");
 199
 200         return 0;
 201 }
 202
 203 void dm_uevent_exit(void)
 204 {
 205         kmem_cache_destroy(_dm_event_cache);
 206 }