drivers/mtd/mtdswap.c

   1 /*
   2  * Swap block device support for MTDs
   3  * Turns an MTD device into a swap device with block wear leveling
   4  *
   5  * Copyright © 2007,2011 Nokia Corporation. All rights reserved.
   6  *
   7  * Authors: Jarkko Lavinen <jarkko.lavinen@nokia.com>
   8  *
   9  * Based on Richard Purdie's earlier implementation in 2007. Background
  10  * support and lock-less operation written by Adrian Hunter.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * version 2 as published by the Free Software Foundation.
  15  *
  16  * This program is distributed in the hope that it will be useful, but
  17  * WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  24  * 02110-1301 USA
  25  */
  26
  27 #include <linux/kernel.h>
  28 #include <linux/module.h>
  29 #include <linux/mtd/mtd.h>
  30 #include <linux/mtd/blktrans.h>
  31 #include <linux/rbtree.h>
  32 #include <linux/sched.h>
  33 #include <linux/slab.h>
  34 #include <linux/vmalloc.h>
  35 #include <linux/genhd.h>
  36 #include <linux/swap.h>
  37 #include <linux/debugfs.h>
  38 #include <linux/seq_file.h>
  39 #include <linux/device.h>
  40 #include <linux/math64.h>
  41
  42 #define MTDSWAP_PREFIX "mtdswap"
  43
  44 /*
  45  * The number of free eraseblocks when GC should stop
  46  */
  47 #define CLEAN_BLOCK_THRESHOLD   20
  48
  49 /*
  50  * Number of free eraseblocks below which GC can also collect low frag
  51  * blocks.
  52  */
  53 #define LOW_FRAG_GC_THRESHOLD   5
  54
  55 /*
  56  * Wear level cost amortization. We want to do wear leveling on the background
  57  * without disturbing gc too much. This is made by defining max GC frequency.
  58  * Frequency value 6 means 1/6 of the GC passes will pick an erase block based
  59  * on the biggest wear difference rather than the biggest dirtiness.
  60  *
  61  * The lower freq2 should be chosen so that it makes sure the maximum erase
  62  * difference will decrease even if a malicious application is deliberately
  63  * trying to make erase differences large.
  64  */
  65 #define MAX_ERASE_DIFF          4000
  66 #define COLLECT_NONDIRTY_BASE   MAX_ERASE_DIFF
  67 #define COLLECT_NONDIRTY_FREQ1  6
  68 #define COLLECT_NONDIRTY_FREQ2  4
  69
  70 #define PAGE_UNDEF              UINT_MAX
  71 #define BLOCK_UNDEF             UINT_MAX
  72 #define BLOCK_ERROR             (UINT_MAX - 1)
  73 #define BLOCK_MAX               (UINT_MAX - 2)
  74
  75 #define EBLOCK_BAD              (1 << 0)
  76 #define EBLOCK_NOMAGIC          (1 << 1)
  77 #define EBLOCK_BITFLIP          (1 << 2)
  78 #define EBLOCK_FAILED           (1 << 3)
  79 #define EBLOCK_READERR          (1 << 4)
  80 #define EBLOCK_IDX_SHIFT        5
  81
  82 struct swap_eb {
  83         struct rb_node rb;
  84         struct rb_root *root;
  85
  86         unsigned int flags;
  87         unsigned int active_count;
  88         unsigned int erase_count;
  89         unsigned int pad;               /* speeds up pointer decrement */
  90 };
  91
  92 #define MTDSWAP_ECNT_MIN(rbroot) (rb_entry(rb_first(rbroot), struct swap_eb, \
  93                                 rb)->erase_count)
  94 #define MTDSWAP_ECNT_MAX(rbroot) (rb_entry(rb_last(rbroot), struct swap_eb, \
  95                                 rb)->erase_count)
  96
  97 struct mtdswap_tree {
  98         struct rb_root root;
  99         unsigned int count;
 100 };
 101
 102 enum {
 103         MTDSWAP_CLEAN,
 104         MTDSWAP_USED,
 105         MTDSWAP_LOWFRAG,
 106         MTDSWAP_HIFRAG,
 107         MTDSWAP_DIRTY,
 108         MTDSWAP_BITFLIP,
 109         MTDSWAP_FAILING,
 110         MTDSWAP_TREE_CNT,
 111 };
 112
 113 struct mtdswap_dev {
 114         struct mtd_blktrans_dev *mbd_dev;
 115         struct mtd_info *mtd;
 116         struct device *dev;
 117
 118         unsigned int *page_data;
 119         unsigned int *revmap;
 120
 121         unsigned int eblks;
 122         unsigned int spare_eblks;
 123         unsigned int pages_per_eblk;
 124         unsigned int max_erase_count;
 125         struct swap_eb *eb_data;
 126
 127         struct mtdswap_tree trees[MTDSWAP_TREE_CNT];
 128
 129         unsigned long long sect_read_count;
 130         unsigned long long sect_write_count;
 131         unsigned long long mtd_write_count;
 132         unsigned long long mtd_read_count;
 133         unsigned long long discard_count;
 134         unsigned long long discard_page_count;
 135
 136         unsigned int curr_write_pos;
 137         struct swap_eb *curr_write;
 138
 139         char *page_buf;
 140         char *oob_buf;
 141 };
 142
 143 struct mtdswap_oobdata {
 144         __le16 magic;
 145         __le32 count;
 146 } __packed;
 147
 148 #define MTDSWAP_MAGIC_CLEAN     0x2095
 149 #define MTDSWAP_MAGIC_DIRTY     (MTDSWAP_MAGIC_CLEAN + 1)
 150 #define MTDSWAP_TYPE_CLEAN      0
 151 #define MTDSWAP_TYPE_DIRTY      1
 152 #define MTDSWAP_OOBSIZE         sizeof(struct mtdswap_oobdata)
 153
 154 #define MTDSWAP_ERASE_RETRIES   3 /* Before marking erase block bad */
 155 #define MTDSWAP_IO_RETRIES      3
 156
 157 enum {
 158         MTDSWAP_SCANNED_CLEAN,
 159         MTDSWAP_SCANNED_DIRTY,
 160         MTDSWAP_SCANNED_BITFLIP,
 161         MTDSWAP_SCANNED_BAD,
 162 };
 163
 164 /*
 165  * In the worst case mtdswap_writesect() has allocated the last clean
 166  * page from the current block and is then pre-empted by the GC
 167  * thread. The thread can consume a full erase block when moving a
 168  * block.
 169  */
 170 #define MIN_SPARE_EBLOCKS       2
 171 #define MIN_ERASE_BLOCKS        (MIN_SPARE_EBLOCKS + 1)
 172
 173 #define TREE_ROOT(d, name) (&d->trees[MTDSWAP_ ## name].root)
 174 #define TREE_EMPTY(d, name) (TREE_ROOT(d, name)->rb_node == NULL)
 175 #define TREE_NONEMPTY(d, name) (!TREE_EMPTY(d, name))
 176 #define TREE_COUNT(d, name) (d->trees[MTDSWAP_ ## name].count)
 177
 178 #define MTDSWAP_MBD_TO_MTDSWAP(dev) ((struct mtdswap_dev *)dev->priv)
 179
 180 static char partitions[128] = "";
 181 module_param_string(partitions, partitions, sizeof(partitions), 0444);
 182 MODULE_PARM_DESC(partitions, "MTD partition numbers to use as swap "
 183                 "partitions=\"1,3,5\"");
 184
 185 static unsigned int spare_eblocks = 10;
 186 module_param(spare_eblocks, uint, 0444);
 187 MODULE_PARM_DESC(spare_eblocks, "Percentage of spare erase blocks for "
 188                 "garbage collection (default 10%)");
 189
 190 static bool header; /* false */
 191 module_param(header, bool, 0444);
 192 MODULE_PARM_DESC(header,
 193                 "Include builtin swap header (default 0, without header)");
 194
 195 static int mtdswap_gc(struct mtdswap_dev *d, unsigned int background);
 196
 197 static loff_t mtdswap_eb_offset(struct mtdswap_dev *d, struct swap_eb *eb)
 198 {
 199         return (loff_t)(eb - d->eb_data) * d->mtd->erasesize;
 200 }
 201
 202 static void mtdswap_eb_detach(struct mtdswap_dev *d, struct swap_eb *eb)
 203 {
 204         unsigned int oldidx;
 205         struct mtdswap_tree *tp;
 206
 207         if (eb->root) {
 208                 tp = container_of(eb->root, struct mtdswap_tree, root);
 209                 oldidx = tp - &d->trees[0];
 210
 211                 d->trees[oldidx].count--;
 212                 rb_erase(&eb->rb, eb->root);
 213         }
 214 }
 215
 216 static void __mtdswap_rb_add(struct rb_root *root, struct swap_eb *eb)
 217 {
 218         struct rb_node **p, *parent = NULL;
 219         struct swap_eb *cur;
 220
 221         p = &root->rb_node;
 222         while (*p) {
 223                 parent = *p;
 224                 cur = rb_entry(parent, struct swap_eb, rb);
 225                 if (eb->erase_count > cur->erase_count)
 226                         p = &(*p)->rb_right;
 227                 else
 228                         p = &(*p)->rb_left;
 229         }
 230
 231         rb_link_node(&eb->rb, parent, p);
 232         rb_insert_color(&eb->rb, root);
 233 }
 234
 235 static void mtdswap_rb_add(struct mtdswap_dev *d, struct swap_eb *eb, int idx)
 236 {
 237         struct rb_root *root;
 238
 239         if (eb->root == &d->trees[idx].root)
 240                 return;
 241
 242         mtdswap_eb_detach(d, eb);
 243         root = &d->trees[idx].root;
 244         __mtdswap_rb_add(root, eb);
 245         eb->root = root;
 246         d->trees[idx].count++;
 247 }
 248
 249 static struct rb_node *mtdswap_rb_index(struct rb_root *root, unsigned int idx)
 250 {
 251         struct rb_node *p;
 252         unsigned int i;
 253
 254         p = rb_first(root);
 255         i = 0;
 256         while (i < idx && p) {
 257                 p = rb_next(p);
 258                 i++;
 259         }
 260
 261         return p;
 262 }
 263
 264 static int mtdswap_handle_badblock(struct mtdswap_dev *d, struct swap_eb *eb)
 265 {
 266         int ret;
 267         loff_t offset;
 268
 269         d->spare_eblks--;
 270         eb->flags |= EBLOCK_BAD;
 271         mtdswap_eb_detach(d, eb);
 272         eb->root = NULL;
 273
 274         /* badblocks not supported */
 275         if (!mtd_can_have_bb(d->mtd))
 276                 return 1;
 277
 278         offset = mtdswap_eb_offset(d, eb);
 279         dev_warn(d->dev, "Marking bad block at %08llx\n", offset);
 280         ret = mtd_block_markbad(d->mtd, offset);
 281
 282         if (ret) {
 283                 dev_warn(d->dev, "Mark block bad failed for block at %08llx "
 284                         "error %d\n", offset, ret);
 285                 return ret;
 286         }
 287
 288         return 1;
 289
 290 }
 291
 292 static int mtdswap_handle_write_error(struct mtdswap_dev *d, struct swap_eb *eb)
 293 {
 294         unsigned int marked = eb->flags & EBLOCK_FAILED;
 295         struct swap_eb *curr_write = d->curr_write;
 296
 297         eb->flags |= EBLOCK_FAILED;
 298         if (curr_write == eb) {
 299                 d->curr_write = NULL;
 300
 301                 if (!marked && d->curr_write_pos != 0) {
 302                         mtdswap_rb_add(d, eb, MTDSWAP_FAILING);
 303                         return 0;
 304                 }
 305         }
 306
 307         return mtdswap_handle_badblock(d, eb);
 308 }
 309
 310 static int mtdswap_read_oob(struct mtdswap_dev *d, loff_t from,
 311                         struct mtd_oob_ops *ops)
 312 {
 313         int ret = mtd_read_oob(d->mtd, from, ops);
 314
 315         if (mtd_is_bitflip(ret))
 316                 return ret;
 317
 318         if (ret) {
 319                 dev_warn(d->dev, "Read OOB failed %d for block at %08llx\n",
 320                         ret, from);
 321                 return ret;
 322         }
 323
 324         if (ops->oobretlen < ops->ooblen) {
 325                 dev_warn(d->dev, "Read OOB return short read (%zd bytes not "
 326                         "%zd) for block at %08llx\n",
 327                         ops->oobretlen, ops->ooblen, from);
 328                 return -EIO;
 329         }
 330
 331         return 0;
 332 }
 333
 334 static int mtdswap_read_markers(struct mtdswap_dev *d, struct swap_eb *eb)
 335 {
 336         struct mtdswap_oobdata *data, *data2;
 337         int ret;
 338         loff_t offset;
 339         struct mtd_oob_ops ops;
 340
 341         offset = mtdswap_eb_offset(d, eb);
 342
 343         /* Check first if the block is bad. */
 344         if (mtd_can_have_bb(d->mtd) && mtd_block_isbad(d->mtd, offset))
 345                 return MTDSWAP_SCANNED_BAD;
 346
 347         ops.ooblen = 2 * d->mtd->oobavail;
 348         ops.oobbuf = d->oob_buf;
 349         ops.ooboffs = 0;
 350         ops.datbuf = NULL;
 351         ops.mode = MTD_OPS_AUTO_OOB;
 352
 353         ret = mtdswap_read_oob(d, offset, &ops);
 354
 355         if (ret && !mtd_is_bitflip(ret))
 356                 return ret;
 357
 358         data = (struct mtdswap_oobdata *)d->oob_buf;
 359         data2 = (struct mtdswap_oobdata *)
 360                 (d->oob_buf + d->mtd->oobavail);
 361
 362         if (le16_to_cpu(data->magic) == MTDSWAP_MAGIC_CLEAN) {
 363                 eb->erase_count = le32_to_cpu(data->count);
 364                 if (mtd_is_bitflip(ret))
 365                         ret = MTDSWAP_SCANNED_BITFLIP;
 366                 else {
 367                         if (le16_to_cpu(data2->magic) == MTDSWAP_MAGIC_DIRTY)
 368                                 ret = MTDSWAP_SCANNED_DIRTY;
 369                         else
 370                                 ret = MTDSWAP_SCANNED_CLEAN;
 371                 }
 372         } else {
 373                 eb->flags |= EBLOCK_NOMAGIC;
 374                 ret = MTDSWAP_SCANNED_DIRTY;
 375         }
 376
 377         return ret;
 378 }
 379
 380 static int mtdswap_write_marker(struct mtdswap_dev *d, struct swap_eb *eb,
 381                                 u16 marker)
 382 {
 383         struct mtdswap_oobdata n;
 384         int ret;
 385         loff_t offset;
 386         struct mtd_oob_ops ops;
 387
 388         ops.ooboffs = 0;
 389         ops.oobbuf = (uint8_t *)&n;
 390         ops.mode = MTD_OPS_AUTO_OOB;
 391         ops.datbuf = NULL;
 392
 393         if (marker == MTDSWAP_TYPE_CLEAN) {
 394                 n.magic = cpu_to_le16(MTDSWAP_MAGIC_CLEAN);
 395                 n.count = cpu_to_le32(eb->erase_count);
 396                 ops.ooblen = MTDSWAP_OOBSIZE;
 397                 offset = mtdswap_eb_offset(d, eb);
 398         } else {
 399                 n.magic = cpu_to_le16(MTDSWAP_MAGIC_DIRTY);
 400                 ops.ooblen = sizeof(n.magic);
 401                 offset = mtdswap_eb_offset(d, eb) + d->mtd->writesize;
 402         }
 403
 404         ret = mtd_write_oob(d->mtd, offset, &ops);
 405
 406         if (ret) {
 407                 dev_warn(d->dev, "Write OOB failed for block at %08llx "
 408                         "error %d\n", offset, ret);
 409                 if (ret == -EIO || mtd_is_eccerr(ret))
 410                         mtdswap_handle_write_error(d, eb);
 411                 return ret;
 412         }
 413
 414         if (ops.oobretlen != ops.ooblen) {
 415                 dev_warn(d->dev, "Short OOB write for block at %08llx: "
 416                         "%zd not %zd\n",
 417                         offset, ops.oobretlen, ops.ooblen);
 418                 return ret;
 419         }
 420
 421         return 0;
 422 }
 423
 424 /*
 425  * Are there any erase blocks without MAGIC_CLEAN header, presumably
 426  * because power was cut off after erase but before header write? We
 427  * need to guestimate the erase count.
 428  */
 429 static void mtdswap_check_counts(struct mtdswap_dev *d)
 430 {
 431         struct rb_root hist_root = RB_ROOT;
 432         struct rb_node *medrb;
 433         struct swap_eb *eb;
 434         unsigned int i, cnt, median;
 435
 436         cnt = 0;
 437         for (i = 0; i < d->eblks; i++) {
 438                 eb = d->eb_data + i;
 439
 440                 if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_BAD | EBLOCK_READERR))
 441                         continue;
 442
 443                 __mtdswap_rb_add(&hist_root, eb);
 444                 cnt++;
 445         }
 446
 447         if (cnt == 0)
 448                 return;
 449
 450         medrb = mtdswap_rb_index(&hist_root, cnt / 2);
 451         median = rb_entry(medrb, struct swap_eb, rb)->erase_count;
 452
 453         d->max_erase_count = MTDSWAP_ECNT_MAX(&hist_root);
 454
 455         for (i = 0; i < d->eblks; i++) {
 456                 eb = d->eb_data + i;
 457
 458                 if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_READERR))
 459                         eb->erase_count = median;
 460
 461                 if (eb->flags & (EBLOCK_NOMAGIC | EBLOCK_BAD | EBLOCK_READERR))
 462                         continue;
 463
 464                 rb_erase(&eb->rb, &hist_root);
 465         }
 466 }
 467
 468 static void mtdswap_scan_eblks(struct mtdswap_dev *d)
 469 {
 470         int status;
 471         unsigned int i, idx;
 472         struct swap_eb *eb;
 473
 474         for (i = 0; i < d->eblks; i++) {
 475                 eb = d->eb_data + i;
 476
 477                 status = mtdswap_read_markers(d, eb);
 478                 if (status < 0)
 479                         eb->flags |= EBLOCK_READERR;
 480                 else if (status == MTDSWAP_SCANNED_BAD) {
 481                         eb->flags |= EBLOCK_BAD;
 482                         continue;
 483                 }
 484
 485                 switch (status) {
 486                 case MTDSWAP_SCANNED_CLEAN:
 487                         idx = MTDSWAP_CLEAN;
 488                         break;
 489                 case MTDSWAP_SCANNED_DIRTY:
 490                 case MTDSWAP_SCANNED_BITFLIP:
 491                         idx = MTDSWAP_DIRTY;
 492                         break;
 493                 default:
 494                         idx = MTDSWAP_FAILING;
 495                 }
 496
 497                 eb->flags |= (idx << EBLOCK_IDX_SHIFT);
 498         }
 499
 500         mtdswap_check_counts(d);
 501
 502         for (i = 0; i < d->eblks; i++) {
 503                 eb = d->eb_data + i;
 504
 505                 if (eb->flags & EBLOCK_BAD)
 506                         continue;
 507
 508                 idx = eb->flags >> EBLOCK_IDX_SHIFT;
 509                 mtdswap_rb_add(d, eb, idx);
 510         }
 511 }
 512
 513 /*
 514  * Place eblk into a tree corresponding to its number of active blocks
 515  * it contains.
 516  */
 517 static void mtdswap_store_eb(struct mtdswap_dev *d, struct swap_eb *eb)
 518 {
 519         unsigned int weight = eb->active_count;
 520         unsigned int maxweight = d->pages_per_eblk;
 521
 522         if (eb == d->curr_write)
 523                 return;
 524
 525         if (eb->flags & EBLOCK_BITFLIP)
 526                 mtdswap_rb_add(d, eb, MTDSWAP_BITFLIP);
 527         else if (eb->flags & (EBLOCK_READERR | EBLOCK_FAILED))
 528                 mtdswap_rb_add(d, eb, MTDSWAP_FAILING);
 529         if (weight == maxweight)
 530                 mtdswap_rb_add(d, eb, MTDSWAP_USED);
 531         else if (weight == 0)
 532                 mtdswap_rb_add(d, eb, MTDSWAP_DIRTY);
 533         else if (weight > (maxweight/2))
 534                 mtdswap_rb_add(d, eb, MTDSWAP_LOWFRAG);
 535         else
 536                 mtdswap_rb_add(d, eb, MTDSWAP_HIFRAG);
 537 }
 538
 539 static int mtdswap_erase_block(struct mtdswap_dev *d, struct swap_eb *eb)
 540 {
 541         struct mtd_info *mtd = d->mtd;
 542         struct erase_info erase;
 543         unsigned int retries = 0;
 544         int ret;
 545
 546         eb->erase_count++;
 547         if (eb->erase_count > d->max_erase_count)
 548                 d->max_erase_count = eb->erase_count;
 549
 550 retry:
 551         memset(&erase, 0, sizeof(struct erase_info));
 552         erase.addr      = mtdswap_eb_offset(d, eb);
 553         erase.len       = mtd->erasesize;
 554
 555         ret = mtd_erase(mtd, &erase);
 556         if (ret) {
 557                 if (retries++ < MTDSWAP_ERASE_RETRIES) {
 558                         dev_warn(d->dev,
 559                                 "erase of erase block %#llx on %s failed",
 560                                 erase.addr, mtd->name);
 561                         yield();
 562                         goto retry;
 563                 }
 564
 565                 dev_err(d->dev, "Cannot erase erase block %#llx on %s\n",
 566                         erase.addr, mtd->name);
 567
 568                 mtdswap_handle_badblock(d, eb);
 569                 return -EIO;
 570         }
 571
 572         return 0;
 573 }
 574
 575 static int mtdswap_map_free_block(struct mtdswap_dev *d, unsigned int page,
 576                                 unsigned int *block)
 577 {
 578         int ret;
 579         struct swap_eb *old_eb = d->curr_write;
 580         struct rb_root *clean_root;
 581         struct swap_eb *eb;
 582
 583         if (old_eb == NULL || d->curr_write_pos >= d->pages_per_eblk) {
 584                 do {
 585                         if (TREE_EMPTY(d, CLEAN))
 586                                 return -ENOSPC;
 587
 588                         clean_root = TREE_ROOT(d, CLEAN);
 589                         eb = rb_entry(rb_first(clean_root), struct swap_eb, rb);
 590                         rb_erase(&eb->rb, clean_root);
 591                         eb->root = NULL;
 592                         TREE_COUNT(d, CLEAN)--;
 593
 594                         ret = mtdswap_write_marker(d, eb, MTDSWAP_TYPE_DIRTY);
 595                 } while (ret == -EIO || mtd_is_eccerr(ret));
 596
 597                 if (ret)
 598                         return ret;
 599
 600                 d->curr_write_pos = 0;
 601                 d->curr_write = eb;
 602                 if (old_eb)
 603                         mtdswap_store_eb(d, old_eb);
 604         }
 605
 606         *block = (d->curr_write - d->eb_data) * d->pages_per_eblk +
 607                 d->curr_write_pos;
 608
 609         d->curr_write->active_count++;
 610         d->revmap[*block] = page;
 611         d->curr_write_pos++;
 612
 613         return 0;
 614 }
 615
 616 static unsigned int mtdswap_free_page_cnt(struct mtdswap_dev *d)
 617 {
 618         return TREE_COUNT(d, CLEAN) * d->pages_per_eblk +
 619                 d->pages_per_eblk - d->curr_write_pos;
 620 }
 621
 622 static unsigned int mtdswap_enough_free_pages(struct mtdswap_dev *d)
 623 {
 624         return mtdswap_free_page_cnt(d) > d->pages_per_eblk;
 625 }
 626
 627 static int mtdswap_write_block(struct mtdswap_dev *d, char *buf,
 628                         unsigned int page, unsigned int *bp, int gc_context)
 629 {
 630         struct mtd_info *mtd = d->mtd;
 631         struct swap_eb *eb;
 632         size_t retlen;
 633         loff_t writepos;
 634         int ret;
 635
 636 retry:
 637         if (!gc_context)
 638                 while (!mtdswap_enough_free_pages(d))
 639                         if (mtdswap_gc(d, 0) > 0)
 640                                 return -ENOSPC;
 641
 642         ret = mtdswap_map_free_block(d, page, bp);
 643         eb = d->eb_data + (*bp / d->pages_per_eblk);
 644
 645         if (ret == -EIO || mtd_is_eccerr(ret)) {
 646                 d->curr_write = NULL;
 647                 eb->active_count--;
 648                 d->revmap[*bp] = PAGE_UNDEF;
 649                 goto retry;
 650         }
 651
 652         if (ret < 0)
 653                 return ret;
 654
 655         writepos = (loff_t)*bp << PAGE_SHIFT;
 656         ret =  mtd_write(mtd, writepos, PAGE_SIZE, &retlen, buf);
 657         if (ret == -EIO || mtd_is_eccerr(ret)) {
 658                 d->curr_write_pos--;
 659                 eb->active_count--;
 660                 d->revmap[*bp] = PAGE_UNDEF;
 661                 mtdswap_handle_write_error(d, eb);
 662                 goto retry;
 663         }
 664
 665         if (ret < 0) {
 666                 dev_err(d->dev, "Write to MTD device failed: %d (%zd written)",
 667                         ret, retlen);
 668                 goto err;
 669         }
 670
 671         if (retlen != PAGE_SIZE) {
 672                 dev_err(d->dev, "Short write to MTD device: %zd written",
 673                         retlen);
 674                 ret = -EIO;
 675                 goto err;
 676         }
 677
 678         return ret;
 679
 680 err:
 681         d->curr_write_pos--;
 682         eb->active_count--;
 683         d->revmap[*bp] = PAGE_UNDEF;
 684
 685         return ret;
 686 }
 687
 688 static int mtdswap_move_block(struct mtdswap_dev *d, unsigned int oldblock,
 689                 unsigned int *newblock)
 690 {
 691         struct mtd_info *mtd = d->mtd;
 692         struct swap_eb *eb, *oldeb;
 693         int ret;
 694         size_t retlen;
 695         unsigned int page, retries;
 696         loff_t readpos;
 697
 698         page = d->revmap[oldblock];
 699         readpos = (loff_t) oldblock << PAGE_SHIFT;
 700         retries = 0;
 701
 702 retry:
 703         ret = mtd_read(mtd, readpos, PAGE_SIZE, &retlen, d->page_buf);
 704
 705         if (ret < 0 && !mtd_is_bitflip(ret)) {
 706                 oldeb = d->eb_data + oldblock / d->pages_per_eblk;
 707                 oldeb->flags |= EBLOCK_READERR;
 708
 709                 dev_err(d->dev, "Read Error: %d (block %u)\n", ret,
 710                         oldblock);
 711                 retries++;
 712                 if (retries < MTDSWAP_IO_RETRIES)
 713                         goto retry;
 714
 715                 goto read_error;
 716         }
 717
 718         if (retlen != PAGE_SIZE) {
 719                 dev_err(d->dev, "Short read: %zd (block %u)\n", retlen,
 720                        oldblock);
 721                 ret = -EIO;
 722                 goto read_error;
 723         }
 724
 725         ret = mtdswap_write_block(d, d->page_buf, page, newblock, 1);
 726         if (ret < 0) {
 727                 d->page_data[page] = BLOCK_ERROR;
 728                 dev_err(d->dev, "Write error: %d\n", ret);
 729                 return ret;
 730         }
 731
 732         eb = d->eb_data + *newblock / d->pages_per_eblk;
 733         d->page_data[page] = *newblock;
 734         d->revmap[oldblock] = PAGE_UNDEF;
 735         eb = d->eb_data + oldblock / d->pages_per_eblk;
 736         eb->active_count--;
 737
 738         return 0;
 739
 740 read_error:
 741         d->page_data[page] = BLOCK_ERROR;
 742         d->revmap[oldblock] = PAGE_UNDEF;
 743         return ret;
 744 }
 745
 746 static int mtdswap_gc_eblock(struct mtdswap_dev *d, struct swap_eb *eb)
 747 {
 748         unsigned int i, block, eblk_base, newblock;
 749         int ret, errcode;
 750
 751         errcode = 0;
 752         eblk_base = (eb - d->eb_data) * d->pages_per_eblk;
 753
 754         for (i = 0; i < d->pages_per_eblk; i++) {
 755                 if (d->spare_eblks < MIN_SPARE_EBLOCKS)
 756                         return -ENOSPC;
 757
 758                 block = eblk_base + i;
 759                 if (d->revmap[block] == PAGE_UNDEF)
 760                         continue;
 761
 762                 ret = mtdswap_move_block(d, block, &newblock);
 763                 if (ret < 0 && !errcode)
 764                         errcode = ret;
 765         }
 766
 767         return errcode;
 768 }
 769
 770 static int __mtdswap_choose_gc_tree(struct mtdswap_dev *d)
 771 {
 772         int idx, stopat;
 773
 774         if (TREE_COUNT(d, CLEAN) < LOW_FRAG_GC_THRESHOLD)
 775                 stopat = MTDSWAP_LOWFRAG;
 776         else
 777                 stopat = MTDSWAP_HIFRAG;
 778
 779         for (idx = MTDSWAP_BITFLIP; idx >= stopat; idx--)
 780                 if (d->trees[idx].root.rb_node != NULL)
 781                         return idx;
 782
 783         return -1;
 784 }
 785
 786 static int mtdswap_wlfreq(unsigned int maxdiff)
 787 {
 788         unsigned int h, x, y, dist, base;
 789
 790         /*
 791          * Calculate linear ramp down from f1 to f2 when maxdiff goes from
 792          * MAX_ERASE_DIFF to MAX_ERASE_DIFF + COLLECT_NONDIRTY_BASE.  Similar
 793          * to triangle with height f1 - f1 and width COLLECT_NONDIRTY_BASE.
 794          */
 795
 796         dist = maxdiff - MAX_ERASE_DIFF;
 797         if (dist > COLLECT_NONDIRTY_BASE)
 798                 dist = COLLECT_NONDIRTY_BASE;
 799
 800         /*
 801          * Modelling the slop as right angular triangle with base
 802          * COLLECT_NONDIRTY_BASE and height freq1 - freq2. The ratio y/x is
 803          * equal to the ratio h/base.
 804          */
 805         h = COLLECT_NONDIRTY_FREQ1 - COLLECT_NONDIRTY_FREQ2;
 806         base = COLLECT_NONDIRTY_BASE;
 807
 808         x = dist - base;
 809         y = (x * h + base / 2) / base;
 810
 811         return COLLECT_NONDIRTY_FREQ2 + y;
 812 }
 813
 814 static int mtdswap_choose_wl_tree(struct mtdswap_dev *d)
 815 {
 816         static unsigned int pick_cnt;
 817         unsigned int i, idx = -1, wear, max;
 818         struct rb_root *root;
 819
 820         max = 0;
 821         for (i = 0; i <= MTDSWAP_DIRTY; i++) {
 822                 root = &d->trees[i].root;
 823                 if (root->rb_node == NULL)
 824                         continue;
 825
 826                 wear = d->max_erase_count - MTDSWAP_ECNT_MIN(root);
 827                 if (wear > max) {
 828                         max = wear;
 829                         idx = i;
 830                 }
 831         }
 832
 833         if (max > MAX_ERASE_DIFF && pick_cnt >= mtdswap_wlfreq(max) - 1) {
 834                 pick_cnt = 0;
 835                 return idx;
 836         }
 837
 838         pick_cnt++;
 839         return -1;
 840 }
 841
 842 static int mtdswap_choose_gc_tree(struct mtdswap_dev *d,
 843                                 unsigned int background)
 844 {
 845         int idx;
 846
 847         if (TREE_NONEMPTY(d, FAILING) &&
 848                 (background || (TREE_EMPTY(d, CLEAN) && TREE_EMPTY(d, DIRTY))))
 849                 return MTDSWAP_FAILING;
 850
 851         idx = mtdswap_choose_wl_tree(d);
 852         if (idx >= MTDSWAP_CLEAN)
 853                 return idx;
 854
 855         return __mtdswap_choose_gc_tree(d);
 856 }
 857
 858 static struct swap_eb *mtdswap_pick_gc_eblk(struct mtdswap_dev *d,
 859                                         unsigned int background)
 860 {
 861         struct rb_root *rp = NULL;
 862         struct swap_eb *eb = NULL;
 863         int idx;
 864
 865         if (background && TREE_COUNT(d, CLEAN) > CLEAN_BLOCK_THRESHOLD &&
 866                 TREE_EMPTY(d, DIRTY) && TREE_EMPTY(d, FAILING))
 867                 return NULL;
 868
 869         idx = mtdswap_choose_gc_tree(d, background);
 870         if (idx < 0)
 871                 return NULL;
 872
 873         rp = &d->trees[idx].root;
 874         eb = rb_entry(rb_first(rp), struct swap_eb, rb);
 875
 876         rb_erase(&eb->rb, rp);
 877         eb->root = NULL;
 878         d->trees[idx].count--;
 879         return eb;
 880 }
 881
 882 static unsigned int mtdswap_test_patt(unsigned int i)
 883 {
 884         return i % 2 ? 0x55555555 : 0xAAAAAAAA;
 885 }
 886
 887 static unsigned int mtdswap_eblk_passes(struct mtdswap_dev *d,
 888                                         struct swap_eb *eb)
 889 {
 890         struct mtd_info *mtd = d->mtd;
 891         unsigned int test, i, j, patt, mtd_pages;
 892         loff_t base, pos;
 893         unsigned int *p1 = (unsigned int *)d->page_buf;
 894         unsigned char *p2 = (unsigned char *)d->oob_buf;
 895         struct mtd_oob_ops ops;
 896         int ret;
 897
 898         ops.mode = MTD_OPS_AUTO_OOB;
 899         ops.len = mtd->writesize;
 900         ops.ooblen = mtd->oobavail;
 901         ops.ooboffs = 0;
 902         ops.datbuf = d->page_buf;
 903         ops.oobbuf = d->oob_buf;
 904         base = mtdswap_eb_offset(d, eb);
 905         mtd_pages = d->pages_per_eblk * PAGE_SIZE / mtd->writesize;
 906
 907         for (test = 0; test < 2; test++) {
 908                 pos = base;
 909                 for (i = 0; i < mtd_pages; i++) {
 910                         patt = mtdswap_test_patt(test + i);
 911                         memset(d->page_buf, patt, mtd->writesize);
 912                         memset(d->oob_buf, patt, mtd->oobavail);
 913                         ret = mtd_write_oob(mtd, pos, &ops);
 914                         if (ret)
 915                                 goto error;
 916
 917                         pos += mtd->writesize;
 918                 }
 919
 920                 pos = base;
 921                 for (i = 0; i < mtd_pages; i++) {
 922                         ret = mtd_read_oob(mtd, pos, &ops);
 923                         if (ret)
 924                                 goto error;
 925
 926                         patt = mtdswap_test_patt(test + i);
 927                         for (j = 0; j < mtd->writesize/sizeof(int); j++)
 928                                 if (p1[j] != patt)
 929                                         goto error;
 930
 931                         for (j = 0; j < mtd->oobavail; j++)
 932                                 if (p2[j] != (unsigned char)patt)
 933                                         goto error;
 934
 935                         pos += mtd->writesize;
 936                 }
 937
 938                 ret = mtdswap_erase_block(d, eb);
 939                 if (ret)
 940                         goto error;
 941         }
 942
 943         eb->flags &= ~EBLOCK_READERR;
 944         return 1;
 945
 946 error:
 947         mtdswap_handle_badblock(d, eb);
 948         return 0;
 949 }
 950
 951 static int mtdswap_gc(struct mtdswap_dev *d, unsigned int background)
 952 {
 953         struct swap_eb *eb;
 954         int ret;
 955
 956         if (d->spare_eblks < MIN_SPARE_EBLOCKS)
 957                 return 1;
 958
 959         eb = mtdswap_pick_gc_eblk(d, background);
 960         if (!eb)
 961                 return 1;
 962
 963         ret = mtdswap_gc_eblock(d, eb);
 964         if (ret == -ENOSPC)
 965                 return 1;
 966
 967         if (eb->flags & EBLOCK_FAILED) {
 968                 mtdswap_handle_badblock(d, eb);
 969                 return 0;
 970         }
 971
 972         eb->flags &= ~EBLOCK_BITFLIP;
 973         ret = mtdswap_erase_block(d, eb);
 974         if ((eb->flags & EBLOCK_READERR) &&
 975                 (ret || !mtdswap_eblk_passes(d, eb)))
 976                 return 0;
 977
 978         if (ret == 0)
 979                 ret = mtdswap_write_marker(d, eb, MTDSWAP_TYPE_CLEAN);
 980
 981         if (ret == 0)
 982                 mtdswap_rb_add(d, eb, MTDSWAP_CLEAN);
 983         else if (ret != -EIO && !mtd_is_eccerr(ret))
 984                 mtdswap_rb_add(d, eb, MTDSWAP_DIRTY);
 985
 986         return 0;
 987 }
 988
 989 static void mtdswap_background(struct mtd_blktrans_dev *dev)
 990 {
 991         struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev);
 992         int ret;
 993
 994         while (1) {
 995                 ret = mtdswap_gc(d, 1);
 996                 if (ret || mtd_blktrans_cease_background(dev))
 997                         return;
 998         }
 999 }
1000
1001 static void mtdswap_cleanup(struct mtdswap_dev *d)
1002 {
1003         vfree(d->eb_data);
1004         vfree(d->revmap);
1005         vfree(d->page_data);
1006         kfree(d->oob_buf);
1007         kfree(d->page_buf);
1008 }
1009
1010 static int mtdswap_flush(struct mtd_blktrans_dev *dev)
1011 {
1012         struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev);
1013
1014         mtd_sync(d->mtd);
1015         return 0;
1016 }
1017
1018 static unsigned int mtdswap_badblocks(struct mtd_info *mtd, uint64_t size)
1019 {
1020         loff_t offset;
1021         unsigned int badcnt;
1022
1023         badcnt = 0;
1024
1025         if (mtd_can_have_bb(mtd))
1026                 for (offset = 0; offset < size; offset += mtd->erasesize)
1027                         if (mtd_block_isbad(mtd, offset))
1028                                 badcnt++;
1029
1030         return badcnt;
1031 }
1032
1033 static int mtdswap_writesect(struct mtd_blktrans_dev *dev,
1034                         unsigned long page, char *buf)
1035 {
1036         struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev);
1037         unsigned int newblock, mapped;
1038         struct swap_eb *eb;
1039         int ret;
1040
1041         d->sect_write_count++;
1042
1043         if (d->spare_eblks < MIN_SPARE_EBLOCKS)
1044                 return -ENOSPC;
1045
1046         if (header) {
1047                 /* Ignore writes to the header page */
1048                 if (unlikely(page == 0))
1049                         return 0;
1050
1051                 page--;
1052         }
1053
1054         mapped = d->page_data[page];
1055         if (mapped <= BLOCK_MAX) {
1056                 eb = d->eb_data + (mapped / d->pages_per_eblk);
1057                 eb->active_count--;
1058                 mtdswap_store_eb(d, eb);
1059                 d->page_data[page] = BLOCK_UNDEF;
1060                 d->revmap[mapped] = PAGE_UNDEF;
1061         }
1062
1063         ret = mtdswap_write_block(d, buf, page, &newblock, 0);
1064         d->mtd_write_count++;
1065
1066         if (ret < 0)
1067                 return ret;
1068
1069         eb = d->eb_data + (newblock / d->pages_per_eblk);
1070         d->page_data[page] = newblock;
1071
1072         return 0;
1073 }
1074
1075 /* Provide a dummy swap header for the kernel */
1076 static int mtdswap_auto_header(struct mtdswap_dev *d, char *buf)
1077 {
1078         union swap_header *hd = (union swap_header *)(buf);
1079
1080         memset(buf, 0, PAGE_SIZE - 10);
1081
1082         hd->info.version = 1;
1083         hd->info.last_page = d->mbd_dev->size - 1;
1084         hd->info.nr_badpages = 0;
1085
1086         memcpy(buf + PAGE_SIZE - 10, "SWAPSPACE2", 10);
1087
1088         return 0;
1089 }
1090
1091 static int mtdswap_readsect(struct mtd_blktrans_dev *dev,
1092                         unsigned long page, char *buf)
1093 {
1094         struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev);
1095         struct mtd_info *mtd = d->mtd;
1096         unsigned int realblock, retries;
1097         loff_t readpos;
1098         struct swap_eb *eb;
1099         size_t retlen;
1100         int ret;
1101
1102         d->sect_read_count++;
1103
1104         if (header) {
1105                 if (unlikely(page == 0))
1106                         return mtdswap_auto_header(d, buf);
1107
1108                 page--;
1109         }
1110
1111         realblock = d->page_data[page];
1112         if (realblock > BLOCK_MAX) {
1113                 memset(buf, 0x0, PAGE_SIZE);
1114                 if (realblock == BLOCK_UNDEF)
1115                         return 0;
1116                 else
1117                         return -EIO;
1118         }
1119
1120         eb = d->eb_data + (realblock / d->pages_per_eblk);
1121         BUG_ON(d->revmap[realblock] == PAGE_UNDEF);
1122
1123         readpos = (loff_t)realblock << PAGE_SHIFT;
1124         retries = 0;
1125
1126 retry:
1127         ret = mtd_read(mtd, readpos, PAGE_SIZE, &retlen, buf);
1128
1129         d->mtd_read_count++;
1130         if (mtd_is_bitflip(ret)) {
1131                 eb->flags |= EBLOCK_BITFLIP;
1132                 mtdswap_rb_add(d, eb, MTDSWAP_BITFLIP);
1133                 ret = 0;
1134         }
1135
1136         if (ret < 0) {
1137                 dev_err(d->dev, "Read error %d\n", ret);
1138                 eb->flags |= EBLOCK_READERR;
1139                 mtdswap_rb_add(d, eb, MTDSWAP_FAILING);
1140                 retries++;
1141                 if (retries < MTDSWAP_IO_RETRIES)
1142                         goto retry;
1143
1144                 return ret;
1145         }
1146
1147         if (retlen != PAGE_SIZE) {
1148                 dev_err(d->dev, "Short read %zd\n", retlen);
1149                 return -EIO;
1150         }
1151
1152         return 0;
1153 }
1154
1155 static int mtdswap_discard(struct mtd_blktrans_dev *dev, unsigned long first,
1156                         unsigned nr_pages)
1157 {
1158         struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev);
1159         unsigned long page;
1160         struct swap_eb *eb;
1161         unsigned int mapped;
1162
1163         d->discard_count++;
1164
1165         for (page = first; page < first + nr_pages; page++) {
1166                 mapped = d->page_data[page];
1167                 if (mapped <= BLOCK_MAX) {
1168                         eb = d->eb_data + (mapped / d->pages_per_eblk);
1169                         eb->active_count--;
1170                         mtdswap_store_eb(d, eb);
1171                         d->page_data[page] = BLOCK_UNDEF;
1172                         d->revmap[mapped] = PAGE_UNDEF;
1173                         d->discard_page_count++;
1174                 } else if (mapped == BLOCK_ERROR) {
1175                         d->page_data[page] = BLOCK_UNDEF;
1176                         d->discard_page_count++;
1177                 }
1178         }
1179
1180         return 0;
1181 }
1182
1183 static int mtdswap_show(struct seq_file *s, void *data)
1184 {
1185         struct mtdswap_dev *d = (struct mtdswap_dev *) s->private;
1186         unsigned long sum;
1187         unsigned int count[MTDSWAP_TREE_CNT];
1188         unsigned int min[MTDSWAP_TREE_CNT];
1189         unsigned int max[MTDSWAP_TREE_CNT];
1190         unsigned int i, cw = 0, cwp = 0, cwecount = 0, bb_cnt, mapped, pages;
1191         uint64_t use_size;
1192         static const char * const name[] = {
1193                 "clean", "used", "low", "high", "dirty", "bitflip", "failing"
1194         };
1195
1196         mutex_lock(&d->mbd_dev->lock);
1197
1198         for (i = 0; i < MTDSWAP_TREE_CNT; i++) {
1199                 struct rb_root *root = &d->trees[i].root;
1200
1201                 if (root->rb_node) {
1202                         count[i] = d->trees[i].count;
1203                         min[i] = MTDSWAP_ECNT_MIN(root);
1204                         max[i] = MTDSWAP_ECNT_MAX(root);
1205                 } else
1206                         count[i] = 0;
1207         }
1208
1209         if (d->curr_write) {
1210                 cw = 1;
1211                 cwp = d->curr_write_pos;
1212                 cwecount = d->curr_write->erase_count;
1213         }
1214
1215         sum = 0;
1216         for (i = 0; i < d->eblks; i++)
1217                 sum += d->eb_data[i].erase_count;
1218
1219         use_size = (uint64_t)d->eblks * d->mtd->erasesize;
1220         bb_cnt = mtdswap_badblocks(d->mtd, use_size);
1221
1222         mapped = 0;
1223         pages = d->mbd_dev->size;
1224         for (i = 0; i < pages; i++)
1225                 if (d->page_data[i] != BLOCK_UNDEF)
1226                         mapped++;
1227
1228         mutex_unlock(&d->mbd_dev->lock);
1229
1230         for (i = 0; i < MTDSWAP_TREE_CNT; i++) {
1231                 if (!count[i])
1232                         continue;
1233
1234                 if (min[i] != max[i])
1235                         seq_printf(s, "%s:\t%5d erase blocks, erased min %d, "
1236                                 "max %d times\n",
1237                                 name[i], count[i], min[i], max[i]);
1238                 else
1239                         seq_printf(s, "%s:\t%5d erase blocks, all erased %d "
1240                                 "times\n", name[i], count[i], min[i]);
1241         }
1242
1243         if (bb_cnt)
1244                 seq_printf(s, "bad:\t%5u erase blocks\n", bb_cnt);
1245
1246         if (cw)
1247                 seq_printf(s, "current erase block: %u pages used, %u free, "
1248                         "erased %u times\n",
1249                         cwp, d->pages_per_eblk - cwp, cwecount);
1250
1251         seq_printf(s, "total erasures: %lu\n", sum);
1252
1253         seq_puts(s, "\n");
1254
1255         seq_printf(s, "mtdswap_readsect count: %llu\n", d->sect_read_count);
1256         seq_printf(s, "mtdswap_writesect count: %llu\n", d->sect_write_count);
1257         seq_printf(s, "mtdswap_discard count: %llu\n", d->discard_count);
1258         seq_printf(s, "mtd read count: %llu\n", d->mtd_read_count);
1259         seq_printf(s, "mtd write count: %llu\n", d->mtd_write_count);
1260         seq_printf(s, "discarded pages count: %llu\n", d->discard_page_count);
1261
1262         seq_puts(s, "\n");
1263         seq_printf(s, "total pages: %u\n", pages);
1264         seq_printf(s, "pages mapped: %u\n", mapped);
1265
1266         return 0;
1267 }
1268
1269 static int mtdswap_open(struct inode *inode, struct file *file)
1270 {
1271         return single_open(file, mtdswap_show, inode->i_private);
1272 }
1273
1274 static const struct file_operations mtdswap_fops = {
1275         .open           = mtdswap_open,
1276         .read           = seq_read,
1277         .llseek         = seq_lseek,
1278         .release        = single_release,
1279 };
1280
1281 static int mtdswap_add_debugfs(struct mtdswap_dev *d)
1282 {
1283         struct dentry *root = d->mtd->dbg.dfs_dir;
1284         struct dentry *dent;
1285
1286         if (!IS_ENABLED(CONFIG_DEBUG_FS))
1287                 return 0;
1288
1289         if (IS_ERR_OR_NULL(root))
1290                 return -1;
1291
1292         dent = debugfs_create_file("mtdswap_stats", S_IRUSR, root, d,
1293                                 &mtdswap_fops);
1294         if (!dent) {
1295                 dev_err(d->dev, "debugfs_create_file failed\n");
1296                 return -1;
1297         }
1298
1299         return 0;
1300 }
1301
1302 static int mtdswap_init(struct mtdswap_dev *d, unsigned int eblocks,
1303                         unsigned int spare_cnt)
1304 {
1305         struct mtd_info *mtd = d->mbd_dev->mtd;
1306         unsigned int i, eblk_bytes, pages, blocks;
1307         int ret = -ENOMEM;
1308
1309         d->mtd = mtd;
1310         d->eblks = eblocks;
1311         d->spare_eblks = spare_cnt;
1312         d->pages_per_eblk = mtd->erasesize >> PAGE_SHIFT;
1313
1314         pages = d->mbd_dev->size;
1315         blocks = eblocks * d->pages_per_eblk;
1316
1317         for (i = 0; i < MTDSWAP_TREE_CNT; i++)
1318                 d->trees[i].root = RB_ROOT;
1319
1320         d->page_data = vmalloc(array_size(pages, sizeof(int)));
1321         if (!d->page_data)
1322                 goto page_data_fail;
1323
1324         d->revmap = vmalloc(array_size(blocks, sizeof(int)));
1325         if (!d->revmap)
1326                 goto revmap_fail;
1327
1328         eblk_bytes = sizeof(struct swap_eb)*d->eblks;
1329         d->eb_data = vzalloc(eblk_bytes);
1330         if (!d->eb_data)
1331                 goto eb_data_fail;
1332
1333         for (i = 0; i < pages; i++)
1334                 d->page_data[i] = BLOCK_UNDEF;
1335
1336         for (i = 0; i < blocks; i++)
1337                 d->revmap[i] = PAGE_UNDEF;
1338
1339         d->page_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
1340         if (!d->page_buf)
1341                 goto page_buf_fail;
1342
1343         d->oob_buf = kmalloc_array(2, mtd->oobavail, GFP_KERNEL);
1344         if (!d->oob_buf)
1345                 goto oob_buf_fail;
1346
1347         mtdswap_scan_eblks(d);
1348
1349         return 0;
1350
1351 oob_buf_fail:
1352         kfree(d->page_buf);
1353 page_buf_fail:
1354         vfree(d->eb_data);
1355 eb_data_fail:
1356         vfree(d->revmap);
1357 revmap_fail:
1358         vfree(d->page_data);
1359 page_data_fail:
1360         printk(KERN_ERR "%s: init failed (%d)\n", MTDSWAP_PREFIX, ret);
1361         return ret;
1362 }
1363
1364 static void mtdswap_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
1365 {
1366         struct mtdswap_dev *d;
1367         struct mtd_blktrans_dev *mbd_dev;
1368         char *parts;
1369         char *this_opt;
1370         unsigned long part;
1371         unsigned int eblocks, eavailable, bad_blocks, spare_cnt;
1372         uint64_t swap_size, use_size, size_limit;
1373         int ret;
1374
1375         parts = &partitions[0];
1376         if (!*parts)
1377                 return;
1378
1379         while ((this_opt = strsep(&parts, ",")) != NULL) {
1380                 if (kstrtoul(this_opt, 0, &part) < 0)
1381                         return;
1382
1383                 if (mtd->index == part)
1384                         break;
1385         }
1386
1387         if (mtd->index != part)
1388                 return;
1389
1390         if (mtd->erasesize < PAGE_SIZE || mtd->erasesize % PAGE_SIZE) {
1391                 printk(KERN_ERR "%s: Erase size %u not multiple of PAGE_SIZE "
1392                         "%lu\n", MTDSWAP_PREFIX, mtd->erasesize, PAGE_SIZE);
1393                 return;
1394         }
1395
1396         if (PAGE_SIZE % mtd->writesize || mtd->writesize > PAGE_SIZE) {
1397                 printk(KERN_ERR "%s: PAGE_SIZE %lu not multiple of write size"
1398                         " %u\n", MTDSWAP_PREFIX, PAGE_SIZE, mtd->writesize);
1399                 return;
1400         }
1401
1402         if (!mtd->oobsize || mtd->oobavail < MTDSWAP_OOBSIZE) {
1403                 printk(KERN_ERR "%s: Not enough free bytes in OOB, "
1404                         "%d available, %zu needed.\n",
1405                         MTDSWAP_PREFIX, mtd->oobavail, MTDSWAP_OOBSIZE);
1406                 return;
1407         }
1408
1409         if (spare_eblocks > 100)
1410                 spare_eblocks = 100;
1411
1412         use_size = mtd->size;
1413         size_limit = (uint64_t) BLOCK_MAX * PAGE_SIZE;
1414
1415         if (mtd->size > size_limit) {
1416                 printk(KERN_WARNING "%s: Device too large. Limiting size to "
1417                         "%llu bytes\n", MTDSWAP_PREFIX, size_limit);
1418                 use_size = size_limit;
1419         }
1420
1421         eblocks = mtd_div_by_eb(use_size, mtd);
1422         use_size = (uint64_t)eblocks * mtd->erasesize;
1423         bad_blocks = mtdswap_badblocks(mtd, use_size);
1424         eavailable = eblocks - bad_blocks;
1425
1426         if (eavailable < MIN_ERASE_BLOCKS) {
1427                 printk(KERN_ERR "%s: Not enough erase blocks. %u available, "
1428                         "%d needed\n", MTDSWAP_PREFIX, eavailable,
1429                         MIN_ERASE_BLOCKS);
1430                 return;
1431         }
1432
1433         spare_cnt = div_u64((uint64_t)eavailable * spare_eblocks, 100);
1434
1435         if (spare_cnt < MIN_SPARE_EBLOCKS)
1436                 spare_cnt = MIN_SPARE_EBLOCKS;
1437
1438         if (spare_cnt > eavailable - 1)
1439                 spare_cnt = eavailable - 1;
1440
1441         swap_size = (uint64_t)(eavailable - spare_cnt) * mtd->erasesize +
1442                 (header ? PAGE_SIZE : 0);
1443
1444         printk(KERN_INFO "%s: Enabling MTD swap on device %lu, size %llu KB, "
1445                 "%u spare, %u bad blocks\n",
1446                 MTDSWAP_PREFIX, part, swap_size / 1024, spare_cnt, bad_blocks);
1447
1448         d = kzalloc(sizeof(struct mtdswap_dev), GFP_KERNEL);
1449         if (!d)
1450                 return;
1451
1452         mbd_dev = kzalloc(sizeof(struct mtd_blktrans_dev), GFP_KERNEL);
1453         if (!mbd_dev) {
1454                 kfree(d);
1455                 return;
1456         }
1457
1458         d->mbd_dev = mbd_dev;
1459         mbd_dev->priv = d;
1460
1461         mbd_dev->mtd = mtd;
1462         mbd_dev->devnum = mtd->index;
1463         mbd_dev->size = swap_size >> PAGE_SHIFT;
1464         mbd_dev->tr = tr;
1465
1466         if (!(mtd->flags & MTD_WRITEABLE))
1467                 mbd_dev->readonly = 1;
1468
1469         if (mtdswap_init(d, eblocks, spare_cnt) < 0)
1470                 goto init_failed;
1471
1472         if (add_mtd_blktrans_dev(mbd_dev) < 0)
1473                 goto cleanup;
1474
1475         d->dev = disk_to_dev(mbd_dev->disk);
1476
1477         ret = mtdswap_add_debugfs(d);
1478         if (ret < 0)
1479                 goto debugfs_failed;
1480
1481         return;
1482
1483 debugfs_failed:
1484         del_mtd_blktrans_dev(mbd_dev);
1485
1486 cleanup:
1487         mtdswap_cleanup(d);
1488
1489 init_failed:
1490         kfree(mbd_dev);
1491         kfree(d);
1492 }
1493
1494 static void mtdswap_remove_dev(struct mtd_blktrans_dev *dev)
1495 {
1496         struct mtdswap_dev *d = MTDSWAP_MBD_TO_MTDSWAP(dev);
1497
1498         del_mtd_blktrans_dev(dev);
1499         mtdswap_cleanup(d);
1500         kfree(d);
1501 }
1502
1503 static struct mtd_blktrans_ops mtdswap_ops = {
1504         .name           = "mtdswap",
1505         .major          = 0,
1506         .part_bits      = 0,
1507         .blksize        = PAGE_SIZE,
1508         .flush          = mtdswap_flush,
1509         .readsect       = mtdswap_readsect,
1510         .writesect      = mtdswap_writesect,
1511         .discard        = mtdswap_discard,
1512         .background     = mtdswap_background,
1513         .add_mtd        = mtdswap_add_mtd,
1514         .remove_dev     = mtdswap_remove_dev,
1515         .owner          = THIS_MODULE,
1516 };
1517
1518 static int __init mtdswap_modinit(void)
1519 {
1520         return register_mtd_blktrans(&mtdswap_ops);
1521 }
1522
1523 static void __exit mtdswap_modexit(void)
1524 {
1525         deregister_mtd_blktrans(&mtdswap_ops);
1526 }
1527
1528 module_init(mtdswap_modinit);
1529 module_exit(mtdswap_modexit);
1530
1531
1532 MODULE_LICENSE("GPL");
1533 MODULE_AUTHOR("Jarkko Lavinen <jarkko.lavinen@nokia.com>");
1534 MODULE_DESCRIPTION("Block device access to an MTD suitable for using as "
1535                 "swap space");