fs/ubifs/sb.c

   1 /*
   2  * This file is part of UBIFS.
   3  *
   4  * Copyright (C) 2006-2008 Nokia Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program; if not, write to the Free Software Foundation, Inc., 51
  17  * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  18  *
  19  * Authors: Artem Bityutskiy (Битюцкий Артём)
  20  *          Adrian Hunter
  21  */
  22
  23 /*
  24  * This file implements UBIFS superblock. The superblock is stored at the first
  25  * LEB of the volume and is never changed by UBIFS. Only user-space tools may
  26  * change it. The superblock node mostly contains geometry information.
  27  */
  28
  29 #include "ubifs.h"
  30 #include <linux/slab.h>
  31 #include <linux/random.h>
  32 #include <linux/math64.h>
  33
  34 /*
  35  * Default journal size in logical eraseblocks as a percent of total
  36  * flash size.
  37  */
  38 #define DEFAULT_JNL_PERCENT 5
  39
  40 /* Default maximum journal size in bytes */
  41 #define DEFAULT_MAX_JNL (32*1024*1024)
  42
  43 /* Default indexing tree fanout */
  44 #define DEFAULT_FANOUT 8
  45
  46 /* Default number of data journal heads */
  47 #define DEFAULT_JHEADS_CNT 1
  48
  49 /* Default positions of different LEBs in the main area */
  50 #define DEFAULT_IDX_LEB  0
  51 #define DEFAULT_DATA_LEB 1
  52 #define DEFAULT_GC_LEB   2
  53
  54 /* Default number of LEB numbers in LPT's save table */
  55 #define DEFAULT_LSAVE_CNT 256
  56
  57 /* Default reserved pool size as a percent of maximum free space */
  58 #define DEFAULT_RP_PERCENT 5
  59
  60 /* The default maximum size of reserved pool in bytes */
  61 #define DEFAULT_MAX_RP_SIZE (5*1024*1024)
  62
  63 /* Default time granularity in nanoseconds */
  64 #define DEFAULT_TIME_GRAN 1000000000
  65
  66 /**
  67  * create_default_filesystem - format empty UBI volume.
  68  * @c: UBIFS file-system description object
  69  *
  70  * This function creates default empty file-system. Returns zero in case of
  71  * success and a negative error code in case of failure.
  72  */
  73 static int create_default_filesystem(struct ubifs_info *c)
  74 {
  75         struct ubifs_sb_node *sup;
  76         struct ubifs_mst_node *mst;
  77         struct ubifs_idx_node *idx;
  78         struct ubifs_branch *br;
  79         struct ubifs_ino_node *ino;
  80         struct ubifs_cs_node *cs;
  81         union ubifs_key key;
  82         int err, tmp, jnl_lebs, log_lebs, max_buds, main_lebs, main_first;
  83         int lpt_lebs, lpt_first, orph_lebs, big_lpt, ino_waste, sup_flags = 0;
  84         int min_leb_cnt = UBIFS_MIN_LEB_CNT;
  85         long long tmp64, main_bytes;
  86         __le64 tmp_le64;
  87
  88         /* Some functions called from here depend on the @c->key_len filed */
  89         c->key_len = UBIFS_SK_LEN;
  90
  91         /*
  92          * First of all, we have to calculate default file-system geometry -
  93          * log size, journal size, etc.
  94          */
  95         if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
  96                 /* We can first multiply then divide and have no overflow */
  97                 jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
  98         else
  99                 jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;
 100
 101         if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
 102                 jnl_lebs = UBIFS_MIN_JNL_LEBS;
 103         if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
 104                 jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;
 105
 106         /*
 107          * The log should be large enough to fit reference nodes for all bud
 108          * LEBs. Because buds do not have to start from the beginning of LEBs
 109          * (half of the LEB may contain committed data), the log should
 110          * generally be larger, make it twice as large.
 111          */
 112         tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
 113         log_lebs = tmp / c->leb_size;
 114         /* Plus one LEB reserved for commit */
 115         log_lebs += 1;
 116         if (c->leb_cnt - min_leb_cnt > 8) {
 117                 /* And some extra space to allow writes while committing */
 118                 log_lebs += 1;
 119                 min_leb_cnt += 1;
 120         }
 121
 122         max_buds = jnl_lebs - log_lebs;
 123         if (max_buds < UBIFS_MIN_BUD_LEBS)
 124                 max_buds = UBIFS_MIN_BUD_LEBS;
 125
 126         /*
 127          * Orphan nodes are stored in a separate area. One node can store a lot
 128          * of orphan inode numbers, but when new orphan comes we just add a new
 129          * orphan node. At some point the nodes are consolidated into one
 130          * orphan node.
 131          */
 132         orph_lebs = UBIFS_MIN_ORPH_LEBS;
 133 #ifdef CONFIG_UBIFS_FS_DEBUG
 134         if (c->leb_cnt - min_leb_cnt > 1)
 135                 /*
 136                  * For debugging purposes it is better to have at least 2
 137                  * orphan LEBs, because the orphan subsystem would need to do
 138                  * consolidations and would be stressed more.
 139                  */
 140                 orph_lebs += 1;
 141 #endif
 142
 143         main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS - log_lebs;
 144         main_lebs -= orph_lebs;
 145
 146         lpt_first = UBIFS_LOG_LNUM + log_lebs;
 147         c->lsave_cnt = DEFAULT_LSAVE_CNT;
 148         c->max_leb_cnt = c->leb_cnt;
 149         err = ubifs_create_dflt_lpt(c, &main_lebs, lpt_first, &lpt_lebs,
 150                                     &big_lpt);
 151         if (err)
 152                 return err;
 153
 154         dbg_gen("LEB Properties Tree created (LEBs %d-%d)", lpt_first,
 155                 lpt_first + lpt_lebs - 1);
 156
 157         main_first = c->leb_cnt - main_lebs;
 158
 159         /* Create default superblock */
 160         tmp = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
 161         sup = kzalloc(tmp, GFP_KERNEL);
 162         if (!sup)
 163                 return -ENOMEM;
 164
 165         tmp64 = (long long)max_buds * c->leb_size;
 166         if (big_lpt)
 167                 sup_flags |= UBIFS_FLG_BIGLPT;
 168
 169         sup->ch.node_type  = UBIFS_SB_NODE;
 170         sup->key_hash      = UBIFS_KEY_HASH_R5;
 171         sup->flags         = cpu_to_le32(sup_flags);
 172         sup->min_io_size   = cpu_to_le32(c->min_io_size);
 173         sup->leb_size      = cpu_to_le32(c->leb_size);
 174         sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
 175         sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
 176         sup->max_bud_bytes = cpu_to_le64(tmp64);
 177         sup->log_lebs      = cpu_to_le32(log_lebs);
 178         sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
 179         sup->orph_lebs     = cpu_to_le32(orph_lebs);
 180         sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
 181         sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
 182         sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
 183         sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
 184         sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
 185         if (c->mount_opts.override_compr)
 186                 sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
 187         else
 188                 sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
 189
 190         generate_random_uuid(sup->uuid);
 191
 192         main_bytes = (long long)main_lebs * c->leb_size;
 193         tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
 194         if (tmp64 > DEFAULT_MAX_RP_SIZE)
 195                 tmp64 = DEFAULT_MAX_RP_SIZE;
 196         sup->rp_size = cpu_to_le64(tmp64);
 197         sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
 198
 199         err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0, UBI_LONGTERM);
 200         kfree(sup);
 201         if (err)
 202                 return err;
 203
 204         dbg_gen("default superblock created at LEB 0:0");
 205
 206         /* Create default master node */
 207         mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
 208         if (!mst)
 209                 return -ENOMEM;
 210
 211         mst->ch.node_type = UBIFS_MST_NODE;
 212         mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
 213         mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
 214         mst->cmt_no       = 0;
 215         mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
 216         mst->root_offs    = 0;
 217         tmp = ubifs_idx_node_sz(c, 1);
 218         mst->root_len     = cpu_to_le32(tmp);
 219         mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
 220         mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
 221         mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
 222         mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
 223         mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
 224         mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
 225         mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
 226         mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
 227         mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
 228         mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
 229         mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
 230         mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
 231         mst->lscan_lnum   = cpu_to_le32(main_first);
 232         mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
 233         mst->idx_lebs     = cpu_to_le32(1);
 234         mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
 235
 236         /* Calculate lprops statistics */
 237         tmp64 = main_bytes;
 238         tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
 239         tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
 240         mst->total_free = cpu_to_le64(tmp64);
 241
 242         tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
 243         ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
 244                           UBIFS_INO_NODE_SZ;
 245         tmp64 += ino_waste;
 246         tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
 247         mst->total_dirty = cpu_to_le64(tmp64);
 248
 249         /*  The indexing LEB does not contribute to dark space */
 250         tmp64 = (c->main_lebs - 1) * c->dark_wm;
 251         mst->total_dark = cpu_to_le64(tmp64);
 252
 253         mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
 254
 255         err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0,
 256                                UBI_UNKNOWN);
 257         if (err) {
 258                 kfree(mst);
 259                 return err;
 260         }
 261         err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM + 1, 0,
 262                                UBI_UNKNOWN);
 263         kfree(mst);
 264         if (err)
 265                 return err;
 266
 267         dbg_gen("default master node created at LEB %d:0", UBIFS_MST_LNUM);
 268
 269         /* Create the root indexing node */
 270         tmp = ubifs_idx_node_sz(c, 1);
 271         idx = kzalloc(ALIGN(tmp, c->min_io_size), GFP_KERNEL);
 272         if (!idx)
 273                 return -ENOMEM;
 274
 275         c->key_fmt = UBIFS_SIMPLE_KEY_FMT;
 276         c->key_hash = key_r5_hash;
 277
 278         idx->ch.node_type = UBIFS_IDX_NODE;
 279         idx->child_cnt = cpu_to_le16(1);
 280         ino_key_init(c, &key, UBIFS_ROOT_INO);
 281         br = ubifs_idx_branch(c, idx, 0);
 282         key_write_idx(c, &key, &br->key);
 283         br->lnum = cpu_to_le32(main_first + DEFAULT_DATA_LEB);
 284         br->len  = cpu_to_le32(UBIFS_INO_NODE_SZ);
 285         err = ubifs_write_node(c, idx, tmp, main_first + DEFAULT_IDX_LEB, 0,
 286                                UBI_UNKNOWN);
 287         kfree(idx);
 288         if (err)
 289                 return err;
 290
 291         dbg_gen("default root indexing node created LEB %d:0",
 292                 main_first + DEFAULT_IDX_LEB);
 293
 294         /* Create default root inode */
 295         tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
 296         ino = kzalloc(tmp, GFP_KERNEL);
 297         if (!ino)
 298                 return -ENOMEM;
 299
 300         ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
 301         ino->ch.node_type = UBIFS_INO_NODE;
 302         ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
 303         ino->nlink = cpu_to_le32(2);
 304         tmp_le64 = cpu_to_le64(CURRENT_TIME_SEC.tv_sec);
 305         ino->atime_sec   = tmp_le64;
 306         ino->ctime_sec   = tmp_le64;
 307         ino->mtime_sec   = tmp_le64;
 308         ino->atime_nsec  = 0;
 309         ino->ctime_nsec  = 0;
 310         ino->mtime_nsec  = 0;
 311         ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
 312         ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
 313
 314         /* Set compression enabled by default */
 315         ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
 316
 317         err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
 318                                main_first + DEFAULT_DATA_LEB, 0,
 319                                UBI_UNKNOWN);
 320         kfree(ino);
 321         if (err)
 322                 return err;
 323
 324         dbg_gen("root inode created at LEB %d:0",
 325                 main_first + DEFAULT_DATA_LEB);
 326
 327         /*
 328          * The first node in the log has to be the commit start node. This is
 329          * always the case during normal file-system operation. Write a fake
 330          * commit start node to the log.
 331          */
 332         tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
 333         cs = kzalloc(tmp, GFP_KERNEL);
 334         if (!cs)
 335                 return -ENOMEM;
 336
 337         cs->ch.node_type = UBIFS_CS_NODE;
 338         err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM,
 339                                0, UBI_UNKNOWN);
 340         kfree(cs);
 341
 342         ubifs_msg("default file-system created");
 343         return 0;
 344 }
 345
 346 /**
 347  * validate_sb - validate superblock node.
 348  * @c: UBIFS file-system description object
 349  * @sup: superblock node
 350  *
 351  * This function validates superblock node @sup. Since most of data was read
 352  * from the superblock and stored in @c, the function validates fields in @c
 353  * instead. Returns zero in case of success and %-EINVAL in case of validation
 354  * failure.
 355  */
 356 static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
 357 {
 358         long long max_bytes;
 359         int err = 1, min_leb_cnt;
 360
 361         if (!c->key_hash) {
 362                 err = 2;
 363                 goto failed;
 364         }
 365
 366         if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
 367                 err = 3;
 368                 goto failed;
 369         }
 370
 371         if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
 372                 ubifs_err("min. I/O unit mismatch: %d in superblock, %d real",
 373                           le32_to_cpu(sup->min_io_size), c->min_io_size);
 374                 goto failed;
 375         }
 376
 377         if (le32_to_cpu(sup->leb_size) != c->leb_size) {
 378                 ubifs_err("LEB size mismatch: %d in superblock, %d real",
 379                           le32_to_cpu(sup->leb_size), c->leb_size);
 380                 goto failed;
 381         }
 382
 383         if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
 384             c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
 385             c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
 386             c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
 387                 err = 4;
 388                 goto failed;
 389         }
 390
 391         /*
 392          * Calculate minimum allowed amount of main area LEBs. This is very
 393          * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
 394          * have just read from the superblock.
 395          */
 396         min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
 397         min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
 398
 399         if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
 400                 ubifs_err("bad LEB count: %d in superblock, %d on UBI volume, "
 401                           "%d minimum required", c->leb_cnt, c->vi.size,
 402                           min_leb_cnt);
 403                 goto failed;
 404         }
 405
 406         if (c->max_leb_cnt < c->leb_cnt) {
 407                 ubifs_err("max. LEB count %d less than LEB count %d",
 408                           c->max_leb_cnt, c->leb_cnt);
 409                 goto failed;
 410         }
 411
 412         if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
 413                 err = 7;
 414                 goto failed;
 415         }
 416
 417         if (c->max_bud_bytes < (long long)c->leb_size * UBIFS_MIN_BUD_LEBS ||
 418             c->max_bud_bytes > (long long)c->leb_size * c->main_lebs) {
 419                 err = 8;
 420                 goto failed;
 421         }
 422
 423         if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
 424             c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
 425                 err = 9;
 426                 goto failed;
 427         }
 428
 429         if (c->fanout < UBIFS_MIN_FANOUT ||
 430             ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
 431                 err = 10;
 432                 goto failed;
 433         }
 434
 435         if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
 436             c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
 437             c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
 438                 err = 11;
 439                 goto failed;
 440         }
 441
 442         if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
 443             c->orph_lebs + c->main_lebs != c->leb_cnt) {
 444                 err = 12;
 445                 goto failed;
 446         }
 447
 448         if (c->default_compr < 0 || c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
 449                 err = 13;
 450                 goto failed;
 451         }
 452
 453         max_bytes = c->main_lebs * (long long)c->leb_size;
 454         if (c->rp_size < 0 || max_bytes < c->rp_size) {
 455                 err = 14;
 456                 goto failed;
 457         }
 458
 459         if (le32_to_cpu(sup->time_gran) > 1000000000 ||
 460             le32_to_cpu(sup->time_gran) < 1) {
 461                 err = 15;
 462                 goto failed;
 463         }
 464
 465         return 0;
 466
 467 failed:
 468         ubifs_err("bad superblock, error %d", err);
 469         dbg_dump_node(c, sup);
 470         return -EINVAL;
 471 }
 472
 473 /**
 474  * ubifs_read_sb_node - read superblock node.
 475  * @c: UBIFS file-system description object
 476  *
 477  * This function returns a pointer to the superblock node or a negative error
 478  * code. Note, the user of this function is responsible of kfree()'ing the
 479  * returned superblock buffer.
 480  */
 481 struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
 482 {
 483         struct ubifs_sb_node *sup;
 484         int err;
 485
 486         sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
 487         if (!sup)
 488                 return ERR_PTR(-ENOMEM);
 489
 490         err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
 491                               UBIFS_SB_LNUM, 0);
 492         if (err) {
 493                 kfree(sup);
 494                 return ERR_PTR(err);
 495         }
 496
 497         return sup;
 498 }
 499
 500 /**
 501  * ubifs_write_sb_node - write superblock node.
 502  * @c: UBIFS file-system description object
 503  * @sup: superblock node read with 'ubifs_read_sb_node()'
 504  *
 505  * This function returns %0 on success and a negative error code on failure.
 506  */
 507 int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
 508 {
 509         int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
 510
 511         ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
 512         return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len, UBI_LONGTERM);
 513 }
 514
 515 /**
 516  * ubifs_read_superblock - read superblock.
 517  * @c: UBIFS file-system description object
 518  *
 519  * This function finds, reads and checks the superblock. If an empty UBI volume
 520  * is being mounted, this function creates default superblock. Returns zero in
 521  * case of success, and a negative error code in case of failure.
 522  */
 523 int ubifs_read_superblock(struct ubifs_info *c)
 524 {
 525         int err, sup_flags;
 526         struct ubifs_sb_node *sup;
 527
 528         if (c->empty) {
 529                 err = create_default_filesystem(c);
 530                 if (err)
 531                         return err;
 532         }
 533
 534         sup = ubifs_read_sb_node(c);
 535         if (IS_ERR(sup))
 536                 return PTR_ERR(sup);
 537
 538         c->fmt_version = le32_to_cpu(sup->fmt_version);
 539         c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
 540
 541         /*
 542          * The software supports all previous versions but not future versions,
 543          * due to the unavailability of time-travelling equipment.
 544          */
 545         if (c->fmt_version > UBIFS_FORMAT_VERSION) {
 546                 ubifs_assert(!c->ro_media || c->ro_mount);
 547                 if (!c->ro_mount ||
 548                     c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
 549                         ubifs_err("on-flash format version is w%d/r%d, but "
 550                                   "software only supports up to version "
 551                                   "w%d/r%d", c->fmt_version,
 552                                   c->ro_compat_version, UBIFS_FORMAT_VERSION,
 553                                   UBIFS_RO_COMPAT_VERSION);
 554                         if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
 555                                 ubifs_msg("only R/O mounting is possible");
 556                                 err = -EROFS;
 557                         } else
 558                                 err = -EINVAL;
 559                         goto out;
 560                 }
 561
 562                 /*
 563                  * The FS is mounted R/O, and the media format is
 564                  * R/O-compatible with the UBIFS implementation, so we can
 565                  * mount.
 566                  */
 567                 c->rw_incompat = 1;
 568         }
 569
 570         if (c->fmt_version < 3) {
 571                 ubifs_err("on-flash format version %d is not supported",
 572                           c->fmt_version);
 573                 err = -EINVAL;
 574                 goto out;
 575         }
 576
 577         switch (sup->key_hash) {
 578         case UBIFS_KEY_HASH_R5:
 579                 c->key_hash = key_r5_hash;
 580                 c->key_hash_type = UBIFS_KEY_HASH_R5;
 581                 break;
 582
 583         case UBIFS_KEY_HASH_TEST:
 584                 c->key_hash = key_test_hash;
 585                 c->key_hash_type = UBIFS_KEY_HASH_TEST;
 586                 break;
 587         };
 588
 589         c->key_fmt = sup->key_fmt;
 590
 591         switch (c->key_fmt) {
 592         case UBIFS_SIMPLE_KEY_FMT:
 593                 c->key_len = UBIFS_SK_LEN;
 594                 break;
 595         default:
 596                 ubifs_err("unsupported key format");
 597                 err = -EINVAL;
 598                 goto out;
 599         }
 600
 601         c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
 602         c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
 603         c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
 604         c->log_lebs      = le32_to_cpu(sup->log_lebs);
 605         c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
 606         c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
 607         c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
 608         c->fanout        = le32_to_cpu(sup->fanout);
 609         c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
 610         c->rp_size       = le64_to_cpu(sup->rp_size);
 611         c->rp_uid        = le32_to_cpu(sup->rp_uid);
 612         c->rp_gid        = le32_to_cpu(sup->rp_gid);
 613         sup_flags        = le32_to_cpu(sup->flags);
 614         if (!c->mount_opts.override_compr)
 615                 c->default_compr = le16_to_cpu(sup->default_compr);
 616
 617         c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
 618         memcpy(&c->uuid, &sup->uuid, 16);
 619         c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
 620         c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
 621
 622         /* Automatically increase file system size to the maximum size */
 623         c->old_leb_cnt = c->leb_cnt;
 624         if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
 625                 c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
 626                 if (c->ro_mount)
 627                         dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
 628                                 c->old_leb_cnt, c->leb_cnt);
 629                 else {
 630                         dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
 631                                 c->old_leb_cnt, c->leb_cnt);
 632                         sup->leb_cnt = cpu_to_le32(c->leb_cnt);
 633                         err = ubifs_write_sb_node(c, sup);
 634                         if (err)
 635                                 goto out;
 636                         c->old_leb_cnt = c->leb_cnt;
 637                 }
 638         }
 639
 640         c->log_bytes = (long long)c->log_lebs * c->leb_size;
 641         c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
 642         c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
 643         c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
 644         c->orph_first = c->lpt_last + 1;
 645         c->orph_last = c->orph_first + c->orph_lebs - 1;
 646         c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
 647         c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
 648         c->main_first = c->leb_cnt - c->main_lebs;
 649
 650         err = validate_sb(c, sup);
 651 out:
 652         kfree(sup);
 653         return err;
 654 }
 655
 656 /**
 657  * fixup_leb - fixup/unmap an LEB containing free space.
 658  * @c: UBIFS file-system description object
 659  * @lnum: the LEB number to fix up
 660  * @len: number of used bytes in LEB (starting at offset 0)
 661  *
 662  * This function reads the contents of the given LEB number @lnum, then fixes
 663  * it up, so that empty min. I/O units in the end of LEB are actually erased on
 664  * flash (rather than being just all-0xff real data). If the LEB is completely
 665  * empty, it is simply unmapped.
 666  */
 667 static int fixup_leb(struct ubifs_info *c, int lnum, int len)
 668 {
 669         int err;
 670
 671         ubifs_assert(len >= 0);
 672         ubifs_assert(len % c->min_io_size == 0);
 673         ubifs_assert(len < c->leb_size);
 674
 675         if (len == 0) {
 676                 dbg_mnt("unmap empty LEB %d", lnum);
 677                 return ubi_leb_unmap(c->ubi, lnum);
 678         }
 679
 680         dbg_mnt("fixup LEB %d, data len %d", lnum, len);
 681         err = ubi_read(c->ubi, lnum, c->sbuf, 0, len);
 682         if (err)
 683                 return err;
 684
 685         return ubi_leb_change(c->ubi, lnum, c->sbuf, len, UBI_UNKNOWN);
 686 }
 687
 688 /**
 689  * fixup_free_space - find & remap all LEBs containing free space.
 690  * @c: UBIFS file-system description object
 691  *
 692  * This function walks through all LEBs in the filesystem and fiexes up those
 693  * containing free/empty space.
 694  */
 695 static int fixup_free_space(struct ubifs_info *c)
 696 {
 697         int lnum, err = 0;
 698         struct ubifs_lprops *lprops;
 699
 700         ubifs_get_lprops(c);
 701
 702         /* Fixup LEBs in the master area */
 703         for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {
 704                 err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);
 705                 if (err)
 706                         goto out;
 707         }
 708
 709         /* Unmap unused log LEBs */
 710         lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
 711         while (lnum != c->ltail_lnum) {
 712                 err = fixup_leb(c, lnum, 0);
 713                 if (err)
 714                         goto out;
 715                 lnum = ubifs_next_log_lnum(c, lnum);
 716         }
 717
 718         /* Fixup the current log head */
 719         err = fixup_leb(c, c->lhead_lnum, c->lhead_offs);
 720         if (err)
 721                 goto out;
 722
 723         /* Fixup LEBs in the LPT area */
 724         for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
 725                 int free = c->ltab[lnum - c->lpt_first].free;
 726
 727                 if (free > 0) {
 728                         err = fixup_leb(c, lnum, c->leb_size - free);
 729                         if (err)
 730                                 goto out;
 731                 }
 732         }
 733
 734         /* Unmap LEBs in the orphans area */
 735         for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
 736                 err = fixup_leb(c, lnum, 0);
 737                 if (err)
 738                         goto out;
 739         }
 740
 741         /* Fixup LEBs in the main area */
 742         for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {
 743                 lprops = ubifs_lpt_lookup(c, lnum);
 744                 if (IS_ERR(lprops)) {
 745                         err = PTR_ERR(lprops);
 746                         goto out;
 747                 }
 748
 749                 if (lprops->free > 0) {
 750                         err = fixup_leb(c, lnum, c->leb_size - lprops->free);
 751                         if (err)
 752                                 goto out;
 753                 }
 754         }
 755
 756 out:
 757         ubifs_release_lprops(c);
 758         return err;
 759 }
 760
 761 /**
 762  * ubifs_fixup_free_space - find & fix all LEBs with free space.
 763  * @c: UBIFS file-system description object
 764  *
 765  * This function fixes up LEBs containing free space on first mount, if the
 766  * appropriate flag was set when the FS was created. Each LEB with one or more
 767  * empty min. I/O unit (i.e. free-space-count > 0) is re-written, to make sure
 768  * the free space is actually erased. E.g., this is necessary for some NAND
 769  * chips, since the free space may have been programmed like real "0xff" data
 770  * (generating a non-0xff ECC), causing future writes to the not-really-erased
 771  * NAND pages to behave badly. After the space is fixed up, the superblock flag
 772  * is cleared, so that this is skipped for all future mounts.
 773  */
 774 int ubifs_fixup_free_space(struct ubifs_info *c)
 775 {
 776         int err;
 777         struct ubifs_sb_node *sup;
 778
 779         ubifs_assert(c->space_fixup);
 780         ubifs_assert(!c->ro_mount);
 781
 782         ubifs_msg("start fixing up free space");
 783
 784         err = fixup_free_space(c);
 785         if (err)
 786                 return err;
 787
 788         sup = ubifs_read_sb_node(c);
 789         if (IS_ERR(sup))
 790                 return PTR_ERR(sup);
 791
 792         /* Free-space fixup is no longer required */
 793         c->space_fixup = 0;
 794         sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
 795
 796         err = ubifs_write_sb_node(c, sup);
 797         kfree(sup);
 798         if (err)
 799                 return err;
 800
 801         ubifs_msg("free space fixup complete");
 802         return err;
 803 }