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  * ubi_wl_get_peb - get a physical eraseblock.
 176  * @ubi: UBI device description object
 177  *
 178  * This function returns a physical eraseblock in case of success and a
 179  * negative error code in case of failure.
 180  * Returns with ubi->fm_eba_sem held in read mode!
 181  */
 182 int ubi_wl_get_peb(struct ubi_device *ubi)
 183 {
 184         int ret, retried = 0;
 185         struct ubi_fm_pool *pool = &ubi->fm_pool;
 186         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
 187
 188 again:
 189         down_read(&ubi->fm_eba_sem);
 190         spin_lock(&ubi->wl_lock);
 191
 192         /* We check here also for the WL pool because at this point we can
 193          * refill the WL pool synchronous. */
 194         if (pool->used == pool->size || wl_pool->used == wl_pool->size) {
 195                 spin_unlock(&ubi->wl_lock);
 196                 up_read(&ubi->fm_eba_sem);
 197                 ret = ubi_update_fastmap(ubi);
 198                 if (ret) {
 199                         ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
 200                         down_read(&ubi->fm_eba_sem);
 201                         return -ENOSPC;
 202                 }
 203                 down_read(&ubi->fm_eba_sem);
 204                 spin_lock(&ubi->wl_lock);
 205         }
 206
 207         if (pool->used == pool->size) {
 208                 spin_unlock(&ubi->wl_lock);
 209                 if (retried) {
 210                         ubi_err(ubi, "Unable to get a free PEB from user WL pool");
 211                         ret = -ENOSPC;
 212                         goto out;
 213                 }
 214                 retried = 1;
 215                 up_read(&ubi->fm_eba_sem);
 216                 goto again;
 217         }
 218
 219         ubi_assert(pool->used < pool->size);
 220         ret = pool->pebs[pool->used++];
 221         prot_queue_add(ubi, ubi->lookuptbl[ret]);
 222         spin_unlock(&ubi->wl_lock);
 223 out:
 224         return ret;
 225 }
 226
 227 /* get_peb_for_wl - returns a PEB to be used internally by the WL sub-system.
 228  *
 229  * @ubi: UBI device description object
 230  */
 231 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
 232 {
 233         struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
 234         int pnum;
 235
 236         if (pool->used == pool->size) {
 237                 /* We cannot update the fastmap here because this
 238                  * function is called in atomic context.
 239                  * Let's fail here and refill/update it as soon as possible. */
 240                 if (!ubi->fm_work_scheduled) {
 241                         ubi->fm_work_scheduled = 1;
 242                         schedule_work(&ubi->fm_work);
 243                 }
 244                 return NULL;
 245         }
 246
 247         pnum = pool->pebs[pool->used++];
 248         return ubi->lookuptbl[pnum];
 249 }
 250
 251 /**
 252  * ubi_ensure_anchor_pebs - schedule wear-leveling to produce an anchor PEB.
 253  * @ubi: UBI device description object
 254  */
 255 int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
 256 {
 257         struct ubi_work *wrk;
 258
 259         spin_lock(&ubi->wl_lock);
 260         if (ubi->wl_scheduled) {
 261                 spin_unlock(&ubi->wl_lock);
 262                 return 0;
 263         }
 264         ubi->wl_scheduled = 1;
 265         spin_unlock(&ubi->wl_lock);
 266
 267         wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
 268         if (!wrk) {
 269                 spin_lock(&ubi->wl_lock);
 270                 ubi->wl_scheduled = 0;
 271                 spin_unlock(&ubi->wl_lock);
 272                 return -ENOMEM;
 273         }
 274
 275         wrk->anchor = 1;
 276         wrk->func = &wear_leveling_worker;
 277         schedule_ubi_work(ubi, wrk);
 278         return 0;
 279 }
 280
 281 /**
 282  * ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
 283  * sub-system.
 284  * see: ubi_wl_put_peb()
 285  *
 286  * @ubi: UBI device description object
 287  * @fm_e: physical eraseblock to return
 288  * @lnum: the last used logical eraseblock number for the PEB
 289  * @torture: if this physical eraseblock has to be tortured
 290  */
 291 int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
 292                       int lnum, int torture)
 293 {
 294         struct ubi_wl_entry *e;
 295         int vol_id, pnum = fm_e->pnum;
 296
 297         dbg_wl("PEB %d", pnum);
 298
 299         ubi_assert(pnum >= 0);
 300         ubi_assert(pnum < ubi->peb_count);
 301
 302         spin_lock(&ubi->wl_lock);
 303         e = ubi->lookuptbl[pnum];
 304
 305         /* This can happen if we recovered from a fastmap the very
 306          * first time and writing now a new one. In this case the wl system
 307          * has never seen any PEB used by the original fastmap.
 308          */
 309         if (!e) {
 310                 e = fm_e;
 311                 ubi_assert(e->ec >= 0);
 312                 ubi->lookuptbl[pnum] = e;
 313         }
 314
 315         spin_unlock(&ubi->wl_lock);
 316
 317         vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
 318         return schedule_erase(ubi, e, vol_id, lnum, torture);
 319 }
 320
 321 /**
 322  * ubi_is_erase_work - checks whether a work is erase work.
 323  * @wrk: The work object to be checked
 324  */
 325 int ubi_is_erase_work(struct ubi_work *wrk)
 326 {
 327         return wrk->func == erase_worker;
 328 }
 329
 330 static void ubi_fastmap_close(struct ubi_device *ubi)
 331 {
 332         int i;
 333
 334         flush_work(&ubi->fm_work);
 335         return_unused_pool_pebs(ubi, &ubi->fm_pool);
 336         return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
 337
 338         if (ubi->fm) {
 339                 for (i = 0; i < ubi->fm->used_blocks; i++)
 340                         kfree(ubi->fm->e[i]);
 341         }
 342         kfree(ubi->fm);
 343 }
 344
 345 /**
 346  * may_reserve_for_fm - tests whether a PEB shall be reserved for fastmap.
 347  * See find_mean_wl_entry()
 348  *
 349  * @ubi: UBI device description object
 350  * @e: physical eraseblock to return
 351  * @root: RB tree to test against.
 352  */
 353 static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
 354                                            struct ubi_wl_entry *e,
 355                                            struct rb_root *root) {
 356         if (e && !ubi->fm_disabled && !ubi->fm &&
 357             e->pnum < UBI_FM_MAX_START)
 358                 e = rb_entry(rb_next(root->rb_node),
 359                              struct ubi_wl_entry, u.rb);
 360
 361         return e;
 362 }