drivers/mtd/ubi/fastmap-wl.c

   1 /*
   2  * Copyright (c) 2012 Linutronix GmbH
   3  * Copyright (c) 2014 sigma star gmbh
   4  * Author: Richard Weinberger <richard@nod.at>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  13  * the GNU General Public License for more details.
  14  *
  15  */
  16
  17 /**
  18  * update_fastmap_work_fn - calls ubi_update_fastmap from a work queue
  19  * @wrk: the work description object
  20  */
  21 static void update_fastmap_work_fn(struct work_struct *wrk)
  22 {
  23         struct ubi_device *ubi = container_of(wrk, struct ubi_device, fm_work);
  24
  25         ubi_update_fastmap(ubi);
  26         spin_lock(&ubi->wl_lock);
  27         ubi->fm_work_scheduled = 0;
  28         spin_unlock(&ubi->wl_lock);
  29 }
  30
  31 /**
  32  * find_anchor_wl_entry - find wear-leveling entry to used as anchor PEB.
  33  * @root: the RB-tree where to look for
  34  */
  35 static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root)
  36 {
  37         struct rb_node *p;
  38         struct ubi_wl_entry *e, *victim = NULL;
  39         int max_ec = UBI_MAX_ERASECOUNTER;
  40
  41         ubi_rb_for_each_entry(p, e, root, u.rb) {
  42                 if (e->pnum < UBI_FM_MAX_START && e->ec < max_ec) {
  43                         victim = e;
  44                         max_ec = e->ec;
  45                 }
  46         }
  47
  48         return victim;
  49 }
  50
  51 /**
  52  * return_unused_pool_pebs - returns unused PEB to the free tree.
  53  * @ubi: UBI device description object
  54  * @pool: fastmap pool description object
  55  */
  56 static void return_unused_pool_pebs(struct ubi_device *ubi,
  57                                     struct ubi_fm_pool *pool)
  58 {
  59         int i;
  60         struct ubi_wl_entry *e;
  61
  62         for (i = pool->used; i < pool->size; i++) {
  63                 e = ubi->lookuptbl[pool->pebs[i]];
  64                 wl_tree_add(e, &ubi->free);
  65                 ubi->free_count++;
  66         }
  67 }
  68
  69 static int anchor_pebs_avalible(struct rb_root *root)
  70 {
  71         struct rb_node *p;
  72         struct ubi_wl_entry *e;
  73
  74         ubi_rb_for_each_entry(p, e, root, u.rb)
  75                 if (e->pnum < UBI_FM_MAX_START)
  76                         return 1;
  77
  78         return 0;
  79 }
  80
  81 /**
  82  * ubi_wl_get_fm_peb - find a physical erase block with a given maximal number.
  83  * @ubi: UBI device description object
  84  * @anchor: This PEB will be used as anchor PEB by fastmap
  85  *
  86  * The function returns a physical erase block with a given maximal number
  87  * and removes it from the wl subsystem.
  88  * Must be called with wl_lock held!
  89  */
  90 struct ubi_wl_entry *ubi_wl_get_fm_peb(struct ubi_device *ubi, int anchor)
  91 {
  92         struct ubi_wl_entry *e = NULL;
  93
  94         if (!ubi->free.rb_node || (ubi->free_count - ubi->beb_rsvd_pebs < 1))
  95                 goto out;
  96
  97         if (anchor)
  98                 e = find_anchor_wl_entry(&ubi->free);
  99         else
 100                 e = find_mean_wl_entry(ubi, &ubi->free);
 101
 102         if (!e)
 103                 goto out;
 104
 105         self_check_in_wl_tree(ubi, e, &ubi->free);
 106
 107         /* remove it from the free list,
 108          * the wl subsystem does no longer know this erase block */
 109         rb_erase(&e->u.rb, &ubi->free);
 110         ubi->free_count--;
 111 out:
 112         return e;
 113 }
 114
 115 /**
 116  * ubi_refill_pools - refills all fastmap PEB pools.
 117  * @ubi: UBI device description object
 118  */
 119 void ubi_refill_pools(struct ubi_device *ubi)
 120 {
 121         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
 122         struct ubi_fm_pool *pool = &ubi->fm_pool;
 123         struct ubi_wl_entry *e;
 124         int enough;
 125
 126         spin_lock(&ubi->wl_lock);
 127
 128         return_unused_pool_pebs(ubi, wl_pool);
 129         return_unused_pool_pebs(ubi, pool);
 130
 131         wl_pool->size = 0;
 132         pool->size = 0;
 133
 134         for (;;) {
 135                 enough = 0;
 136                 if (pool->size < pool->max_size) {
 137                         if (!ubi->free.rb_node)
 138                                 break;
 139
 140                         e = wl_get_wle(ubi);
 141                         if (!e)
 142                                 break;
 143
 144                         pool->pebs[pool->size] = e->pnum;
 145                         pool->size++;
 146                 } else
 147                         enough++;
 148
 149                 if (wl_pool->size < wl_pool->max_size) {
 150                         if (!ubi->free.rb_node ||
 151                            (ubi->free_count - ubi->beb_rsvd_pebs < 5))
 152                                 break;
 153
 154                         e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
 155                         self_check_in_wl_tree(ubi, e, &ubi->free);
 156                         rb_erase(&e->u.rb, &ubi->free);
 157                         ubi->free_count--;
 158
 159                         wl_pool->pebs[wl_pool->size] = e->pnum;
 160                         wl_pool->size++;
 161                 } else
 162                         enough++;
 163
 164                 if (enough == 2)
 165                         break;
 166         }
 167
 168         wl_pool->used = 0;
 169         pool->used = 0;
 170
 171         spin_unlock(&ubi->wl_lock);
 172 }
 173
 174 /**
 175  * produce_free_peb - produce a free physical eraseblock.
 176  * @ubi: UBI device description object
 177  *
 178  * This function tries to make a free PEB by means of synchronous execution of
 179  * pending works. This may be needed if, for example the background thread is
 180  * disabled. Returns zero in case of success and a negative error code in case
 181  * of failure.
 182  */
 183 static int produce_free_peb(struct ubi_device *ubi)
 184 {
 185         int err;
 186
 187         while (!ubi->free.rb_node && ubi->works_count) {
 188                 dbg_wl("do one work synchronously");
 189                 err = do_work(ubi);
 190
 191                 if (err)
 192                         return err;
 193         }
 194
 195         return 0;
 196 }
 197
 198 /**
 199  * ubi_wl_get_peb - get a physical eraseblock.
 200  * @ubi: UBI device description object
 201  *
 202  * This function returns a physical eraseblock in case of success and a
 203  * negative error code in case of failure.
 204  * Returns with ubi->fm_eba_sem held in read mode!
 205  */
 206 int ubi_wl_get_peb(struct ubi_device *ubi)
 207 {
 208         int ret, retried = 0;
 209         struct ubi_fm_pool *pool = &ubi->fm_pool;
 210         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
 211
 212 again:
 213         down_read(&ubi->fm_eba_sem);
 214         spin_lock(&ubi->wl_lock);
 215
 216         /* We check here also for the WL pool because at this point we can
 217          * refill the WL pool synchronous. */
 218         if (pool->used == pool->size || wl_pool->used == wl_pool->size) {
 219                 spin_unlock(&ubi->wl_lock);
 220                 up_read(&ubi->fm_eba_sem);
 221                 ret = ubi_update_fastmap(ubi);
 222                 if (ret) {
 223                         ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
 224                         down_read(&ubi->fm_eba_sem);
 225                         return -ENOSPC;
 226                 }
 227                 down_read(&ubi->fm_eba_sem);
 228                 spin_lock(&ubi->wl_lock);
 229         }
 230
 231         if (pool->used == pool->size) {
 232                 spin_unlock(&ubi->wl_lock);
 233                 if (retried) {
 234                         ubi_err(ubi, "Unable to get a free PEB from user WL pool");
 235                         ret = -ENOSPC;
 236                         goto out;
 237                 }
 238                 retried = 1;
 239                 up_read(&ubi->fm_eba_sem);
 240                 ret = produce_free_peb(ubi);
 241                 if (ret < 0) {
 242                         down_read(&ubi->fm_eba_sem);
 243                         goto out;
 244                 }
 245                 goto again;
 246         }
 247
 248         ubi_assert(pool->used < pool->size);
 249         ret = pool->pebs[pool->used++];
 250         prot_queue_add(ubi, ubi->lookuptbl[ret]);
 251         spin_unlock(&ubi->wl_lock);
 252 out:
 253         return ret;
 254 }
 255
 256 /* get_peb_for_wl - returns a PEB to be used internally by the WL sub-system.
 257  *
 258  * @ubi: UBI device description object
 259  */
 260 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
 261 {
 262         struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
 263         int pnum;
 264
 265         ubi_assert(rwsem_is_locked(&ubi->fm_eba_sem));
 266
 267         if (pool->used == pool->size) {
 268                 /* We cannot update the fastmap here because this
 269                  * function is called in atomic context.
 270                  * Let's fail here and refill/update it as soon as possible. */
 271                 if (!ubi->fm_work_scheduled) {
 272                         ubi->fm_work_scheduled = 1;
 273                         schedule_work(&ubi->fm_work);
 274                 }
 275                 return NULL;
 276         }
 277
 278         pnum = pool->pebs[pool->used++];
 279         return ubi->lookuptbl[pnum];
 280 }
 281
 282 /**
 283  * ubi_ensure_anchor_pebs - schedule wear-leveling to produce an anchor PEB.
 284  * @ubi: UBI device description object
 285  */
 286 int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
 287 {
 288         struct ubi_work *wrk;
 289
 290         spin_lock(&ubi->wl_lock);
 291         if (ubi->wl_scheduled) {
 292                 spin_unlock(&ubi->wl_lock);
 293                 return 0;
 294         }
 295         ubi->wl_scheduled = 1;
 296         spin_unlock(&ubi->wl_lock);
 297
 298         wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
 299         if (!wrk) {
 300                 spin_lock(&ubi->wl_lock);
 301                 ubi->wl_scheduled = 0;
 302                 spin_unlock(&ubi->wl_lock);
 303                 return -ENOMEM;
 304         }
 305
 306         wrk->anchor = 1;
 307         wrk->func = &wear_leveling_worker;
 308         __schedule_ubi_work(ubi, wrk);
 309         return 0;
 310 }
 311
 312 /**
 313  * ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
 314  * sub-system.
 315  * see: ubi_wl_put_peb()
 316  *
 317  * @ubi: UBI device description object
 318  * @fm_e: physical eraseblock to return
 319  * @lnum: the last used logical eraseblock number for the PEB
 320  * @torture: if this physical eraseblock has to be tortured
 321  */
 322 int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
 323                       int lnum, int torture)
 324 {
 325         struct ubi_wl_entry *e;
 326         int vol_id, pnum = fm_e->pnum;
 327
 328         dbg_wl("PEB %d", pnum);
 329
 330         ubi_assert(pnum >= 0);
 331         ubi_assert(pnum < ubi->peb_count);
 332
 333         spin_lock(&ubi->wl_lock);
 334         e = ubi->lookuptbl[pnum];
 335
 336         /* This can happen if we recovered from a fastmap the very
 337          * first time and writing now a new one. In this case the wl system
 338          * has never seen any PEB used by the original fastmap.
 339          */
 340         if (!e) {
 341                 e = fm_e;
 342                 ubi_assert(e->ec >= 0);
 343                 ubi->lookuptbl[pnum] = e;
 344         }
 345
 346         spin_unlock(&ubi->wl_lock);
 347
 348         vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
 349         return schedule_erase(ubi, e, vol_id, lnum, torture, true);
 350 }
 351
 352 /**
 353  * ubi_is_erase_work - checks whether a work is erase work.
 354  * @wrk: The work object to be checked
 355  */
 356 int ubi_is_erase_work(struct ubi_work *wrk)
 357 {
 358         return wrk->func == erase_worker;
 359 }
 360
 361 static void ubi_fastmap_close(struct ubi_device *ubi)
 362 {
 363         int i;
 364
 365         flush_work(&ubi->fm_work);
 366         return_unused_pool_pebs(ubi, &ubi->fm_pool);
 367         return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
 368
 369         if (ubi->fm) {
 370                 for (i = 0; i < ubi->fm->used_blocks; i++)
 371                         kfree(ubi->fm->e[i]);
 372         }
 373         kfree(ubi->fm);
 374 }
 375
 376 /**
 377  * may_reserve_for_fm - tests whether a PEB shall be reserved for fastmap.
 378  * See find_mean_wl_entry()
 379  *
 380  * @ubi: UBI device description object
 381  * @e: physical eraseblock to return
 382  * @root: RB tree to test against.
 383  */
 384 static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
 385                                            struct ubi_wl_entry *e,
 386                                            struct rb_root *root) {
 387         if (e && !ubi->fm_disabled && !ubi->fm &&
 388             e->pnum < UBI_FM_MAX_START)
 389                 e = rb_entry(rb_next(root->rb_node),
 390                              struct ubi_wl_entry, u.rb);
 391
 392         return e;
 393 }