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