drivers/mtd/ubi/fastmap-wl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2012 Linutronix GmbH
   4  * Copyright (c) 2014 sigma star gmbh
   5  * Author: Richard Weinberger <richard@nod.at>
   6  */
   7
   8 /**
   9  * update_fastmap_work_fn - calls ubi_update_fastmap from a work queue
  10  * @wrk: the work description object
  11  */
  12 static void update_fastmap_work_fn(struct work_struct *wrk)
  13 {
  14         struct ubi_device *ubi = container_of(wrk, struct ubi_device, fm_work);
  15
  16         ubi_update_fastmap(ubi);
  17         spin_lock(&ubi->wl_lock);
  18         ubi->fm_work_scheduled = 0;
  19         spin_unlock(&ubi->wl_lock);
  20 }
  21
  22 /**
  23  * find_anchor_wl_entry - find wear-leveling entry to used as anchor PEB.
  24  * @root: the RB-tree where to look for
  25  */
  26 static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root)
  27 {
  28         struct rb_node *p;
  29         struct ubi_wl_entry *e, *victim = NULL;
  30         int max_ec = UBI_MAX_ERASECOUNTER;
  31
  32         ubi_rb_for_each_entry(p, e, root, u.rb) {
  33                 if (e->pnum < UBI_FM_MAX_START && e->ec < max_ec) {
  34                         victim = e;
  35                         max_ec = e->ec;
  36                 }
  37         }
  38
  39         return victim;
  40 }
  41
  42 static inline void return_unused_peb(struct ubi_device *ubi,
  43                                      struct ubi_wl_entry *e)
  44 {
  45         wl_tree_add(e, &ubi->free);
  46         ubi->free_count++;
  47 }
  48
  49 /**
  50  * return_unused_pool_pebs - returns unused PEB to the free tree.
  51  * @ubi: UBI device description object
  52  * @pool: fastmap pool description object
  53  */
  54 static void return_unused_pool_pebs(struct ubi_device *ubi,
  55                                     struct ubi_fm_pool *pool)
  56 {
  57         int i;
  58         struct ubi_wl_entry *e;
  59
  60         for (i = pool->used; i < pool->size; i++) {
  61                 e = ubi->lookuptbl[pool->pebs[i]];
  62                 return_unused_peb(ubi, e);
  63         }
  64 }
  65
  66 /**
  67  * ubi_wl_get_fm_peb - find a physical erase block with a given maximal number.
  68  * @ubi: UBI device description object
  69  * @anchor: This PEB will be used as anchor PEB by fastmap
  70  *
  71  * The function returns a physical erase block with a given maximal number
  72  * and removes it from the wl subsystem.
  73  * Must be called with wl_lock held!
  74  */
  75 struct ubi_wl_entry *ubi_wl_get_fm_peb(struct ubi_device *ubi, int anchor)
  76 {
  77         struct ubi_wl_entry *e = NULL;
  78
  79         if (!ubi->free.rb_node)
  80                 goto out;
  81
  82         if (anchor)
  83                 e = find_anchor_wl_entry(&ubi->free);
  84         else
  85                 e = find_mean_wl_entry(ubi, &ubi->free);
  86
  87         if (!e)
  88                 goto out;
  89
  90         self_check_in_wl_tree(ubi, e, &ubi->free);
  91
  92         /* remove it from the free list,
  93          * the wl subsystem does no longer know this erase block */
  94         rb_erase(&e->u.rb, &ubi->free);
  95         ubi->free_count--;
  96 out:
  97         return e;
  98 }
  99
 100 /*
 101  * wait_free_pebs_for_pool - wait until there enough free pebs
 102  * @ubi: UBI device description object
 103  *
 104  * Wait and execute do_work until there are enough free pebs, fill pool
 105  * as much as we can. This will reduce pool refilling times, which can
 106  * reduce the fastmap updating frequency.
 107  */
 108 static void wait_free_pebs_for_pool(struct ubi_device *ubi)
 109 {
 110         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
 111         struct ubi_fm_pool *pool = &ubi->fm_pool;
 112         int free, expect_free, executed;
 113         /*
 114          * There are at least following free pebs which reserved by UBI:
 115          * 1. WL_RESERVED_PEBS[1]
 116          * 2. EBA_RESERVED_PEBS[1]
 117          * 3. fm pebs - 1: Twice fastmap size deducted by fastmap and fm_anchor
 118          * 4. beb_rsvd_pebs: This value should be get under lock ubi->wl_lock
 119          */
 120         int reserved = WL_RESERVED_PEBS + EBA_RESERVED_PEBS +
 121                        ubi->fm_size / ubi->leb_size - 1 + ubi->fm_pool_rsv_cnt;
 122
 123         do {
 124                 spin_lock(&ubi->wl_lock);
 125                 free = ubi->free_count;
 126                 free += pool->size - pool->used + wl_pool->size - wl_pool->used;
 127                 expect_free = reserved + ubi->beb_rsvd_pebs;
 128                 spin_unlock(&ubi->wl_lock);
 129
 130                 /*
 131                  * Break out if there are no works or work is executed failure,
 132                  * given the fact that erase_worker will schedule itself when
 133                  * -EBUSY is returned from mtd layer caused by system shutdown.
 134                  */
 135                 if (do_work(ubi, &executed) || !executed)
 136                         break;
 137         } while (free < expect_free);
 138 }
 139
 140 /*
 141  * left_free_count - returns the number of free pebs to fill fm pools
 142  * @ubi: UBI device description object
 143  *
 144  * This helper function returns the number of free pebs (deducted
 145  * by fastmap pebs) to fill fm_pool and fm_wl_pool.
 146  */
 147 static int left_free_count(struct ubi_device *ubi)
 148 {
 149         int fm_used = 0;        // fastmap non anchor pebs.
 150
 151         if (!ubi->free.rb_node)
 152                 return 0;
 153
 154         if (!ubi->ro_mode && !ubi->fm_disabled)
 155                 fm_used = ubi->fm_size / ubi->leb_size - 1;
 156
 157         return ubi->free_count - fm_used;
 158 }
 159
 160 /*
 161  * can_fill_pools - whether free PEBs will be left after filling pools
 162  * @ubi: UBI device description object
 163  * @free: current number of free PEBs
 164  *
 165  * Return %1 if there are still left free PEBs after filling pools,
 166  * otherwise %0 is returned.
 167  */
 168 static int can_fill_pools(struct ubi_device *ubi, int free)
 169 {
 170         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
 171         struct ubi_fm_pool *pool = &ubi->fm_pool;
 172         int pool_need = pool->max_size - pool->size +
 173                         wl_pool->max_size - wl_pool->size;
 174
 175         if (free - pool_need < 1)
 176                 return 0;
 177
 178         return 1;
 179 }
 180
 181 /**
 182  * ubi_refill_pools_and_lock - refills all fastmap PEB pools and takes fm locks.
 183  * @ubi: UBI device description object
 184  */
 185 void ubi_refill_pools_and_lock(struct ubi_device *ubi)
 186 {
 187         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
 188         struct ubi_fm_pool *pool = &ubi->fm_pool;
 189         struct ubi_wl_entry *e;
 190         int enough;
 191
 192         if (!ubi->ro_mode && !ubi->fm_disabled)
 193                 wait_free_pebs_for_pool(ubi);
 194
 195         down_write(&ubi->fm_protect);
 196         down_write(&ubi->work_sem);
 197         down_write(&ubi->fm_eba_sem);
 198
 199         spin_lock(&ubi->wl_lock);
 200
 201         return_unused_pool_pebs(ubi, wl_pool);
 202         return_unused_pool_pebs(ubi, pool);
 203
 204         wl_pool->size = 0;
 205         pool->size = 0;
 206
 207         if (ubi->fm_anchor) {
 208                 wl_tree_add(ubi->fm_anchor, &ubi->free);
 209                 ubi->free_count++;
 210                 ubi->fm_anchor = NULL;
 211         }
 212
 213         if (!ubi->fm_disabled)
 214                 /*
 215                  * All available PEBs are in ubi->free, now is the time to get
 216                  * the best anchor PEBs.
 217                  */
 218                 ubi->fm_anchor = ubi_wl_get_fm_peb(ubi, 1);
 219
 220         for (;;) {
 221                 enough = 0;
 222                 if (pool->size < pool->max_size) {
 223                         if (left_free_count(ubi) <= 0)
 224                                 break;
 225
 226                         e = wl_get_wle(ubi);
 227                         if (!e)
 228                                 break;
 229
 230                         pool->pebs[pool->size] = e->pnum;
 231                         pool->size++;
 232                 } else
 233                         enough++;
 234
 235                 if (wl_pool->size < wl_pool->max_size) {
 236                         int left_free = left_free_count(ubi);
 237
 238                         if (left_free <= 0)
 239                                 break;
 240
 241                         e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF,
 242                                           !can_fill_pools(ubi, left_free));
 243                         self_check_in_wl_tree(ubi, e, &ubi->free);
 244                         rb_erase(&e->u.rb, &ubi->free);
 245                         ubi->free_count--;
 246
 247                         wl_pool->pebs[wl_pool->size] = e->pnum;
 248                         wl_pool->size++;
 249                 } else
 250                         enough++;
 251
 252                 if (enough == 2)
 253                         break;
 254         }
 255
 256         wl_pool->used = 0;
 257         pool->used = 0;
 258
 259         spin_unlock(&ubi->wl_lock);
 260 }
 261
 262 /**
 263  * produce_free_peb - produce a free physical eraseblock.
 264  * @ubi: UBI device description object
 265  *
 266  * This function tries to make a free PEB by means of synchronous execution of
 267  * pending works. This may be needed if, for example the background thread is
 268  * disabled. Returns zero in case of success and a negative error code in case
 269  * of failure.
 270  */
 271 static int produce_free_peb(struct ubi_device *ubi)
 272 {
 273         int err;
 274
 275         while (!ubi->free.rb_node && ubi->works_count) {
 276                 dbg_wl("do one work synchronously");
 277                 err = do_work(ubi, NULL);
 278
 279                 if (err)
 280                         return err;
 281         }
 282
 283         return 0;
 284 }
 285
 286 /**
 287  * ubi_wl_get_peb - get a physical eraseblock.
 288  * @ubi: UBI device description object
 289  *
 290  * This function returns a physical eraseblock in case of success and a
 291  * negative error code in case of failure.
 292  * Returns with ubi->fm_eba_sem held in read mode!
 293  */
 294 int ubi_wl_get_peb(struct ubi_device *ubi)
 295 {
 296         int ret, attempts = 0;
 297         struct ubi_fm_pool *pool = &ubi->fm_pool;
 298         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
 299
 300 again:
 301         down_read(&ubi->fm_eba_sem);
 302         spin_lock(&ubi->wl_lock);
 303
 304         /* We check here also for the WL pool because at this point we can
 305          * refill the WL pool synchronous. */
 306         if (pool->used == pool->size || wl_pool->used == wl_pool->size) {
 307                 spin_unlock(&ubi->wl_lock);
 308                 up_read(&ubi->fm_eba_sem);
 309                 ret = ubi_update_fastmap(ubi);
 310                 if (ret) {
 311                         ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
 312                         down_read(&ubi->fm_eba_sem);
 313                         return -ENOSPC;
 314                 }
 315                 down_read(&ubi->fm_eba_sem);
 316                 spin_lock(&ubi->wl_lock);
 317         }
 318
 319         if (pool->used == pool->size) {
 320                 spin_unlock(&ubi->wl_lock);
 321                 attempts++;
 322                 if (attempts == 10) {
 323                         ubi_err(ubi, "Unable to get a free PEB from user WL pool");
 324                         ret = -ENOSPC;
 325                         goto out;
 326                 }
 327                 up_read(&ubi->fm_eba_sem);
 328                 ret = produce_free_peb(ubi);
 329                 if (ret < 0) {
 330                         down_read(&ubi->fm_eba_sem);
 331                         goto out;
 332                 }
 333                 goto again;
 334         }
 335
 336         ubi_assert(pool->used < pool->size);
 337         ret = pool->pebs[pool->used++];
 338         prot_queue_add(ubi, ubi->lookuptbl[ret]);
 339         spin_unlock(&ubi->wl_lock);
 340 out:
 341         return ret;
 342 }
 343
 344 /**
 345  * next_peb_for_wl - returns next PEB to be used internally by the
 346  * WL sub-system.
 347  *
 348  * @ubi: UBI device description object
 349  */
 350 static struct ubi_wl_entry *next_peb_for_wl(struct ubi_device *ubi)
 351 {
 352         struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
 353         int pnum;
 354
 355         if (pool->used == pool->size)
 356                 return NULL;
 357
 358         pnum = pool->pebs[pool->used];
 359         return ubi->lookuptbl[pnum];
 360 }
 361
 362 /**
 363  * need_wear_leveling - checks whether to trigger a wear leveling work.
 364  * UBI fetches free PEB from wl_pool, we check free PEBs from both 'wl_pool'
 365  * and 'ubi->free', because free PEB in 'ubi->free' tree maybe moved into
 366  * 'wl_pool' by ubi_refill_pools().
 367  *
 368  * @ubi: UBI device description object
 369  */
 370 static bool need_wear_leveling(struct ubi_device *ubi)
 371 {
 372         int ec;
 373         struct ubi_wl_entry *e;
 374
 375         if (!ubi->used.rb_node)
 376                 return false;
 377
 378         e = next_peb_for_wl(ubi);
 379         if (!e) {
 380                 if (!ubi->free.rb_node)
 381                         return false;
 382                 e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF, 0);
 383                 ec = e->ec;
 384         } else {
 385                 ec = e->ec;
 386                 if (ubi->free.rb_node) {
 387                         e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF, 0);
 388                         ec = max(ec, e->ec);
 389                 }
 390         }
 391         e = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
 392
 393         return ec - e->ec >= UBI_WL_THRESHOLD;
 394 }
 395
 396 /* get_peb_for_wl - returns a PEB to be used internally by the WL sub-system.
 397  *
 398  * @ubi: UBI device description object
 399  */
 400 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
 401 {
 402         struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
 403         int pnum;
 404
 405         ubi_assert(rwsem_is_locked(&ubi->fm_eba_sem));
 406
 407         if (pool->used == pool->size) {
 408                 /* We cannot update the fastmap here because this
 409                  * function is called in atomic context.
 410                  * Let's fail here and refill/update it as soon as possible. */
 411                 if (!ubi->fm_work_scheduled) {
 412                         ubi->fm_work_scheduled = 1;
 413                         schedule_work(&ubi->fm_work);
 414                 }
 415                 return NULL;
 416         }
 417
 418         pnum = pool->pebs[pool->used++];
 419         return ubi->lookuptbl[pnum];
 420 }
 421
 422 /**
 423  * ubi_ensure_anchor_pebs - schedule wear-leveling to produce an anchor PEB.
 424  * @ubi: UBI device description object
 425  */
 426 int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
 427 {
 428         struct ubi_work *wrk;
 429         struct ubi_wl_entry *anchor;
 430
 431         spin_lock(&ubi->wl_lock);
 432
 433         /* Do we already have an anchor? */
 434         if (ubi->fm_anchor) {
 435                 spin_unlock(&ubi->wl_lock);
 436                 return 0;
 437         }
 438
 439         /* See if we can find an anchor PEB on the list of free PEBs */
 440         anchor = ubi_wl_get_fm_peb(ubi, 1);
 441         if (anchor) {
 442                 ubi->fm_anchor = anchor;
 443                 spin_unlock(&ubi->wl_lock);
 444                 return 0;
 445         }
 446
 447         ubi->fm_do_produce_anchor = 1;
 448         /* No luck, trigger wear leveling to produce a new anchor PEB. */
 449         if (ubi->wl_scheduled) {
 450                 spin_unlock(&ubi->wl_lock);
 451                 return 0;
 452         }
 453         ubi->wl_scheduled = 1;
 454         spin_unlock(&ubi->wl_lock);
 455
 456         wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
 457         if (!wrk) {
 458                 spin_lock(&ubi->wl_lock);
 459                 ubi->wl_scheduled = 0;
 460                 spin_unlock(&ubi->wl_lock);
 461                 return -ENOMEM;
 462         }
 463
 464         wrk->func = &wear_leveling_worker;
 465         __schedule_ubi_work(ubi, wrk);
 466         return 0;
 467 }
 468
 469 /**
 470  * ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
 471  * sub-system.
 472  * see: ubi_wl_put_peb()
 473  *
 474  * @ubi: UBI device description object
 475  * @fm_e: physical eraseblock to return
 476  * @lnum: the last used logical eraseblock number for the PEB
 477  * @torture: if this physical eraseblock has to be tortured
 478  */
 479 int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
 480                       int lnum, int torture)
 481 {
 482         struct ubi_wl_entry *e;
 483         int vol_id, pnum = fm_e->pnum;
 484
 485         dbg_wl("PEB %d", pnum);
 486
 487         ubi_assert(pnum >= 0);
 488         ubi_assert(pnum < ubi->peb_count);
 489
 490         spin_lock(&ubi->wl_lock);
 491         e = ubi->lookuptbl[pnum];
 492
 493         /* This can happen if we recovered from a fastmap the very
 494          * first time and writing now a new one. In this case the wl system
 495          * has never seen any PEB used by the original fastmap.
 496          */
 497         if (!e) {
 498                 e = fm_e;
 499                 ubi_assert(e->ec >= 0);
 500                 ubi->lookuptbl[pnum] = e;
 501         }
 502
 503         spin_unlock(&ubi->wl_lock);
 504
 505         vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
 506         return schedule_erase(ubi, e, vol_id, lnum, torture, true);
 507 }
 508
 509 /**
 510  * ubi_is_erase_work - checks whether a work is erase work.
 511  * @wrk: The work object to be checked
 512  */
 513 int ubi_is_erase_work(struct ubi_work *wrk)
 514 {
 515         return wrk->func == erase_worker;
 516 }
 517
 518 static void ubi_fastmap_close(struct ubi_device *ubi)
 519 {
 520         int i;
 521
 522         return_unused_pool_pebs(ubi, &ubi->fm_pool);
 523         return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
 524
 525         if (ubi->fm_anchor) {
 526                 return_unused_peb(ubi, ubi->fm_anchor);
 527                 ubi->fm_anchor = NULL;
 528         }
 529
 530         if (ubi->fm) {
 531                 for (i = 0; i < ubi->fm->used_blocks; i++)
 532                         kfree(ubi->fm->e[i]);
 533         }
 534         kfree(ubi->fm);
 535 }
 536
 537 /**
 538  * may_reserve_for_fm - tests whether a PEB shall be reserved for fastmap.
 539  * See find_mean_wl_entry()
 540  *
 541  * @ubi: UBI device description object
 542  * @e: physical eraseblock to return
 543  * @root: RB tree to test against.
 544  */
 545 static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
 546                                            struct ubi_wl_entry *e,
 547                                            struct rb_root *root) {
 548         if (e && !ubi->fm_disabled && !ubi->fm && !ubi->fm_anchor &&
 549             e->pnum < UBI_FM_MAX_START)
 550                 e = rb_entry(rb_next(root->rb_node),
 551                              struct ubi_wl_entry, u.rb);
 552
 553         return e;
 554 }