swap.c

   1 /*-*- Mode: C; c-basic-offset: 8 -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <errno.h>
  23 #include <limits.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <sys/epoll.h>
  27 #include <sys/stat.h>
  28 #include <sys/swap.h>
  29
  30 #include "unit.h"
  31 #include "swap.h"
  32 #include "load-fragment.h"
  33 #include "load-dropin.h"
  34 #include "unit-name.h"
  35 #include "dbus-swap.h"
  36
  37 static const UnitActiveState state_translation_table[_SWAP_STATE_MAX] = {
  38         [SWAP_DEAD] = UNIT_INACTIVE,
  39         [SWAP_ACTIVE] = UNIT_ACTIVE,
  40         [SWAP_MAINTAINANCE] = UNIT_INACTIVE
  41 };
  42
  43 static int swap_verify(Swap *s) {
  44         bool b;
  45         char *e;
  46
  47         if (UNIT(s)->meta.load_state != UNIT_LOADED)
  48                   return 0;
  49
  50         if (!(e = unit_name_from_path(s->what, ".swap")))
  51                   return -ENOMEM;
  52
  53         b = unit_has_name(UNIT(s), e);
  54         free(e);
  55
  56         if (!b) {
  57                 log_error("%s: Value of \"What\" and unit name do not match, not loading.\n", UNIT(s)->meta.id);
  58                 return -EINVAL;
  59         }
  60         return 0;
  61 }
  62
  63 static int swap_add_target_links(Swap *s) {
  64         Manager *m = s->meta.manager;
  65         Unit *tu;
  66         int r;
  67
  68         r = manager_load_unit(m, SPECIAL_SWAP_TARGET, NULL, &tu);
  69         if (r < 0)
  70                 return r;
  71
  72         if (!s->no_auto && (r = unit_add_dependency(tu, UNIT_WANTS, UNIT(s), true)) < 0)
  73                 return r;
  74
  75         return unit_add_dependency(UNIT(s), UNIT_BEFORE, tu, true);
  76 }
  77
  78 static int swap_load(Unit *u) {
  79         int r;
  80         Swap *s = SWAP(u);
  81
  82         assert(s);
  83         assert(u->meta.load_state == UNIT_STUB);
  84
  85         /* Load a .swap file */
  86         if ((r = unit_load_fragment_and_dropin_optional(u)) < 0)
  87                 return r;
  88
  89         if (u->meta.load_state == UNIT_LOADED) {
  90                 if (!s->what)
  91                         if (!(s->what = unit_name_to_path(u->meta.id)))
  92                                 return -ENOMEM;
  93
  94                 path_kill_slashes(s->what);
  95
  96                 if ((r = mount_add_node_links(u, s->what)) < 0)
  97                         return r;
  98
  99                 if (!path_startswith(s->what, "/dev/"))
 100                         if ((r = mount_add_path_links(u, s->what, true)) < 0)
 101                                 return r;
 102
 103                 if ((r = swap_add_target_links(s)) < 0)
 104                         return r;
 105         }
 106
 107         return swap_verify(s);
 108 }
 109
 110 int swap_add_one(Manager *m, const char *what, bool no_auto, int prio, bool from_proc_swaps) {
 111         Unit *u;
 112         char *e;
 113         bool delete;
 114         int r;
 115
 116         if (!(e = unit_name_from_path(what, ".swap")))
 117                 return -ENOMEM;
 118
 119         if (!(u = manager_get_unit(m, e))) {
 120                 delete = true;
 121
 122                 if (!(u = unit_new(m))) {
 123                         free(e);
 124                         return -ENOMEM;
 125                 }
 126
 127                 r = unit_add_name(u, e);
 128                 free(e);
 129
 130                 if (r < 0)
 131                         goto fail;
 132
 133                 if (!(SWAP(u)->what = strdup(what))) {
 134                         r = -ENOMEM;
 135                         goto fail;
 136                 }
 137
 138                 if ((r = unit_set_description(u, what)) < 0)
 139                         goto fail;
 140
 141                 unit_add_to_load_queue(u);
 142
 143                 SWAP(u)->from_proc_swaps_only = from_proc_swaps;
 144         } else {
 145                 if (SWAP(u)->from_proc_swaps_only && !from_proc_swaps)
 146                         SWAP(u)->from_proc_swaps_only = false;
 147
 148                 delete = false;
 149                 free(e);
 150         }
 151
 152         if (!from_proc_swaps)
 153                 SWAP(u)->no_auto = no_auto;
 154         else
 155                 SWAP(u)->found_in_proc_swaps = true;
 156
 157         SWAP(u)->priority = prio;
 158
 159         return 0;
 160
 161 fail:
 162         if (delete)
 163                 unit_free(u);
 164
 165         return 0;
 166 }
 167
 168 static void swap_set_state(Swap *s, SwapState state) {
 169         SwapState old_state;
 170         assert(s);
 171
 172         old_state = s->state;
 173         s->state = state;
 174
 175         if (state != old_state)
 176                 log_debug("%s changed %s -> %s",
 177                           UNIT(s)->meta.id,
 178                           swap_state_to_string(old_state),
 179                           swap_state_to_string(state));
 180
 181         unit_notify(UNIT(s), state_translation_table[old_state], state_translation_table[state]);
 182 }
 183
 184 static int swap_coldplug(Unit *u) {
 185         Swap *s = SWAP(u);
 186         SwapState new_state = SWAP_DEAD;
 187
 188         assert(s);
 189         assert(s->state == SWAP_DEAD);
 190
 191         if (s->deserialized_state != s->state)
 192                 new_state = s->deserialized_state;
 193         else if (s->found_in_proc_swaps)
 194                 new_state = SWAP_ACTIVE;
 195
 196         if (new_state != s->state)
 197                 swap_set_state(s, s->deserialized_state);
 198
 199         return 0;
 200 }
 201
 202 static void swap_dump(Unit *u, FILE *f, const char *prefix) {
 203         Swap *s = SWAP(u);
 204
 205         assert(s);
 206
 207         fprintf(f,
 208                 "%sAutomount State: %s\n"
 209                 "%sWhat: %s\n"
 210                 "%sPriority: %i\n"
 211                 "%sNoAuto: %s\n",
 212                 prefix, swap_state_to_string(s->state),
 213                 prefix, s->what,
 214                 prefix, s->priority,
 215                 prefix, yes_no(s->no_auto));
 216 }
 217
 218 static void swap_enter_dead(Swap *s, bool success) {
 219         assert(s);
 220
 221         swap_set_state(s, success ? SWAP_MAINTAINANCE : SWAP_DEAD);
 222 }
 223
 224 static int swap_start(Unit *u) {
 225         Swap *s = SWAP(u);
 226         int r;
 227
 228         assert(s);
 229
 230         assert(s->state == SWAP_DEAD || s->state == SWAP_MAINTAINANCE);
 231
 232         r = swapon(s->what, (s->priority << SWAP_FLAG_PRIO_SHIFT) & SWAP_FLAG_PRIO_MASK);
 233
 234         if (r < 0 && errno != EBUSY) {
 235                 r = -errno;
 236                 swap_enter_dead(s, false);
 237                 return r;
 238         }
 239
 240         swap_set_state(s, SWAP_ACTIVE);
 241         return 0;
 242 }
 243
 244 static int swap_stop(Unit *u) {
 245         Swap *s = SWAP(u);
 246         int r;
 247
 248         assert(s);
 249
 250         assert(s->state == SWAP_ACTIVE);
 251
 252         r = swapoff(s->what);
 253         swap_enter_dead(s, r >= 0 || errno == EINVAL);
 254
 255         return 0;
 256 }
 257
 258 static int swap_serialize(Unit *u, FILE *f, FDSet *fds) {
 259         Swap *s = SWAP(u);
 260
 261         assert(s);
 262         assert(f);
 263         assert(fds);
 264
 265         unit_serialize_item(u, f, "state", swap_state_to_string(s->state));
 266
 267         return 0;
 268 }
 269
 270 static int swap_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
 271         Swap *s = SWAP(u);
 272
 273         assert(s);
 274         assert(fds);
 275
 276         if (streq(key, "state")) {
 277                 SwapState state;
 278
 279                 if ((state = swap_state_from_string(value)) < 0)
 280                         log_debug("Failed to parse state value %s", value);
 281                 else
 282                         s->deserialized_state = state;
 283         } else
 284                 log_debug("Unknown serialization key '%s'", key);
 285
 286         return 0;
 287 }
 288
 289 static UnitActiveState swap_active_state(Unit *u) {
 290         assert(u);
 291
 292         return state_translation_table[SWAP(u)->state];
 293 }
 294
 295 static const char *swap_sub_state_to_string(Unit *u) {
 296         assert(u);
 297
 298         return swap_state_to_string(SWAP(u)->state);
 299 }
 300
 301 static bool swap_check_gc(Unit *u) {
 302         Swap *s = SWAP(u);
 303
 304         assert(s);
 305
 306         return !s->from_proc_swaps_only || s->found_in_proc_swaps;
 307 }
 308
 309 static int swap_load_proc_swaps(Manager *m) {
 310         Meta *meta;
 311
 312         rewind(m->proc_swaps);
 313         fscanf(m->proc_self_mountinfo, "%*s %*s %*s %*s %*s\n");
 314
 315         for (;;) {
 316                 char *dev = NULL, *d;
 317                 int prio = 0, k;
 318
 319                 k = fscanf(m->proc_self_mountinfo,
 320                            "%ms " /* device/file */
 321                            "%*s " /* type of swap */
 322                            "%*s " /* swap size */
 323                            "%*s " /* used */
 324                            "%d\n", /* priority */
 325                            &dev, &prio);
 326
 327                 if (k != 2) {
 328                         if (k == EOF)
 329                                 k = 0;
 330
 331                         free(dev);
 332                         return -EBADMSG;
 333                 }
 334                 if (!(d = cunescape(dev))) {
 335                         free(dev);
 336                         k = -ENOMEM;
 337                         return k;
 338                 }
 339
 340                 k = swap_add_one(m, d, false, prio, true);
 341                 free(dev);
 342                 free(d);
 343
 344                 if (k < 0)
 345                         return k;
 346         }
 347
 348         LIST_FOREACH(units_per_type, meta, m->units_per_type[UNIT_SWAP]) {
 349                 Swap *s = (Swap*) meta;
 350
 351                 if (s->state != SWAP_DEAD && s->state != SWAP_ACTIVE)
 352                         continue;
 353
 354                 if ((s->state == SWAP_DEAD && !s->found_in_proc_swaps) ||
 355                     (s->state == SWAP_ACTIVE && s->found_in_proc_swaps))
 356                         continue;
 357
 358                 swap_set_state(s, s->found_in_proc_swaps ? SWAP_ACTIVE : SWAP_DEAD);
 359
 360                 /* Reset the flags for later calls */
 361                 s->found_in_proc_swaps = false;
 362         }
 363 }
 364
 365 static void swap_shutdown(Manager *m) {
 366         assert(m);
 367
 368         if (m->proc_swaps) {
 369                 fclose(m->proc_swaps);
 370                 m->proc_swaps = NULL;
 371         }
 372 }
 373
 374 static const char* const swap_state_table[_SWAP_STATE_MAX] = {
 375         [SWAP_DEAD] = "dead",
 376         [SWAP_ACTIVE] = "active",
 377         [SWAP_MAINTAINANCE] = "maintainance"
 378 };
 379
 380 DEFINE_STRING_TABLE_LOOKUP(swap_state, SwapState);
 381
 382 static int swap_enumerate(Manager *m) {
 383         int r;
 384         assert(m);
 385
 386         if (!m->proc_swaps &&
 387             !(m->proc_swaps = fopen("/proc/swaps", "er")))
 388                 return -errno;
 389
 390         if ((r = swap_load_proc_swaps(m)) < 0)
 391                 swap_shutdown(m);
 392
 393         return r;
 394 }
 395
 396 const UnitVTable swap_vtable = {
 397         .suffix = ".swap",
 398
 399         .no_alias = true,
 400         .no_instances = true,
 401
 402         .load = swap_load,
 403
 404         .coldplug = swap_coldplug,
 405
 406         .dump = swap_dump,
 407
 408         .start = swap_start,
 409         .stop = swap_stop,
 410
 411         .serialize = swap_serialize,
 412         .deserialize_item = swap_deserialize_item,
 413
 414         .active_state = swap_active_state,
 415         .sub_state_to_string = swap_sub_state_to_string,
 416
 417         .check_gc = swap_check_gc,
 418
 419         .bus_message_handler = bus_swap_message_handler,
 420
 421         .shutdown = swap_shutdown,
 422
 423         .enumerate = swap_enumerate
 424 };