linux/fs/ubifs/sb.c
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   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/math64.h>
  32#include <linux/uuid.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 */
  73static 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        __le32 tmp_le32;
  88        struct timespec64 ts;
  89
  90        /* Some functions called from here depend on the @c->key_len filed */
  91        c->key_len = UBIFS_SK_LEN;
  92
  93        /*
  94         * First of all, we have to calculate default file-system geometry -
  95         * log size, journal size, etc.
  96         */
  97        if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
  98                /* We can first multiply then divide and have no overflow */
  99                jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
 100        else
 101                jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;
 102
 103        if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
 104                jnl_lebs = UBIFS_MIN_JNL_LEBS;
 105        if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
 106                jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;
 107
 108        /*
 109         * The log should be large enough to fit reference nodes for all bud
 110         * LEBs. Because buds do not have to start from the beginning of LEBs
 111         * (half of the LEB may contain committed data), the log should
 112         * generally be larger, make it twice as large.
 113         */
 114        tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
 115        log_lebs = tmp / c->leb_size;
 116        /* Plus one LEB reserved for commit */
 117        log_lebs += 1;
 118        if (c->leb_cnt - min_leb_cnt > 8) {
 119                /* And some extra space to allow writes while committing */
 120                log_lebs += 1;
 121                min_leb_cnt += 1;
 122        }
 123
 124        max_buds = jnl_lebs - log_lebs;
 125        if (max_buds < UBIFS_MIN_BUD_LEBS)
 126                max_buds = UBIFS_MIN_BUD_LEBS;
 127
 128        /*
 129         * Orphan nodes are stored in a separate area. One node can store a lot
 130         * of orphan inode numbers, but when new orphan comes we just add a new
 131         * orphan node. At some point the nodes are consolidated into one
 132         * orphan node.
 133         */
 134        orph_lebs = UBIFS_MIN_ORPH_LEBS;
 135        if (c->leb_cnt - min_leb_cnt > 1)
 136                /*
 137                 * For debugging purposes it is better to have at least 2
 138                 * orphan LEBs, because the orphan subsystem would need to do
 139                 * consolidations and would be stressed more.
 140                 */
 141                orph_lebs += 1;
 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        sup_flags |= UBIFS_FLG_DOUBLE_HASH;
 169
 170        sup->ch.node_type  = UBIFS_SB_NODE;
 171        sup->key_hash      = UBIFS_KEY_HASH_R5;
 172        sup->flags         = cpu_to_le32(sup_flags);
 173        sup->min_io_size   = cpu_to_le32(c->min_io_size);
 174        sup->leb_size      = cpu_to_le32(c->leb_size);
 175        sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
 176        sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
 177        sup->max_bud_bytes = cpu_to_le64(tmp64);
 178        sup->log_lebs      = cpu_to_le32(log_lebs);
 179        sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
 180        sup->orph_lebs     = cpu_to_le32(orph_lebs);
 181        sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
 182        sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
 183        sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
 184        sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
 185        sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
 186        if (c->mount_opts.override_compr)
 187                sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
 188        else
 189                sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);
 190
 191        generate_random_uuid(sup->uuid);
 192
 193        main_bytes = (long long)main_lebs * c->leb_size;
 194        tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
 195        if (tmp64 > DEFAULT_MAX_RP_SIZE)
 196                tmp64 = DEFAULT_MAX_RP_SIZE;
 197        sup->rp_size = cpu_to_le64(tmp64);
 198        sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);
 199
 200        err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0);
 201        kfree(sup);
 202        if (err)
 203                return err;
 204
 205        dbg_gen("default superblock created at LEB 0:0");
 206
 207        /* Create default master node */
 208        mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
 209        if (!mst)
 210                return -ENOMEM;
 211
 212        mst->ch.node_type = UBIFS_MST_NODE;
 213        mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
 214        mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
 215        mst->cmt_no       = 0;
 216        mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
 217        mst->root_offs    = 0;
 218        tmp = ubifs_idx_node_sz(c, 1);
 219        mst->root_len     = cpu_to_le32(tmp);
 220        mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
 221        mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
 222        mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
 223        mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
 224        mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
 225        mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
 226        mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
 227        mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
 228        mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
 229        mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
 230        mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
 231        mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
 232        mst->lscan_lnum   = cpu_to_le32(main_first);
 233        mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
 234        mst->idx_lebs     = cpu_to_le32(1);
 235        mst->leb_cnt      = cpu_to_le32(c->leb_cnt);
 236
 237        /* Calculate lprops statistics */
 238        tmp64 = main_bytes;
 239        tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
 240        tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
 241        mst->total_free = cpu_to_le64(tmp64);
 242
 243        tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
 244        ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
 245                          UBIFS_INO_NODE_SZ;
 246        tmp64 += ino_waste;
 247        tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
 248        mst->total_dirty = cpu_to_le64(tmp64);
 249
 250        /*  The indexing LEB does not contribute to dark space */
 251        tmp64 = ((long long)(c->main_lebs - 1) * c->dark_wm);
 252        mst->total_dark = cpu_to_le64(tmp64);
 253
 254        mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);
 255
 256        err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0);
 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,
 262                               0);
 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        kfree(idx);
 287        if (err)
 288                return err;
 289
 290        dbg_gen("default root indexing node created LEB %d:0",
 291                main_first + DEFAULT_IDX_LEB);
 292
 293        /* Create default root inode */
 294        tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
 295        ino = kzalloc(tmp, GFP_KERNEL);
 296        if (!ino)
 297                return -ENOMEM;
 298
 299        ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
 300        ino->ch.node_type = UBIFS_INO_NODE;
 301        ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
 302        ino->nlink = cpu_to_le32(2);
 303
 304        ktime_get_real_ts64(&ts);
 305        ts = timespec64_trunc(ts, DEFAULT_TIME_GRAN);
 306        tmp_le64 = cpu_to_le64(ts.tv_sec);
 307        ino->atime_sec   = tmp_le64;
 308        ino->ctime_sec   = tmp_le64;
 309        ino->mtime_sec   = tmp_le64;
 310        tmp_le32 = cpu_to_le32(ts.tv_nsec);
 311        ino->atime_nsec  = tmp_le32;
 312        ino->ctime_nsec  = tmp_le32;
 313        ino->mtime_nsec  = tmp_le32;
 314        ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
 315        ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);
 316
 317        /* Set compression enabled by default */
 318        ino->flags = cpu_to_le32(UBIFS_COMPR_FL);
 319
 320        err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
 321                               main_first + DEFAULT_DATA_LEB, 0);
 322        kfree(ino);
 323        if (err)
 324                return err;
 325
 326        dbg_gen("root inode created at LEB %d:0",
 327                main_first + DEFAULT_DATA_LEB);
 328
 329        /*
 330         * The first node in the log has to be the commit start node. This is
 331         * always the case during normal file-system operation. Write a fake
 332         * commit start node to the log.
 333         */
 334        tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
 335        cs = kzalloc(tmp, GFP_KERNEL);
 336        if (!cs)
 337                return -ENOMEM;
 338
 339        cs->ch.node_type = UBIFS_CS_NODE;
 340        err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM, 0);
 341        kfree(cs);
 342        if (err)
 343                return err;
 344
 345        ubifs_msg(c, "default file-system created");
 346        return 0;
 347}
 348
 349/**
 350 * validate_sb - validate superblock node.
 351 * @c: UBIFS file-system description object
 352 * @sup: superblock node
 353 *
 354 * This function validates superblock node @sup. Since most of data was read
 355 * from the superblock and stored in @c, the function validates fields in @c
 356 * instead. Returns zero in case of success and %-EINVAL in case of validation
 357 * failure.
 358 */
 359static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
 360{
 361        long long max_bytes;
 362        int err = 1, min_leb_cnt;
 363
 364        if (!c->key_hash) {
 365                err = 2;
 366                goto failed;
 367        }
 368
 369        if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
 370                err = 3;
 371                goto failed;
 372        }
 373
 374        if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
 375                ubifs_err(c, "min. I/O unit mismatch: %d in superblock, %d real",
 376                          le32_to_cpu(sup->min_io_size), c->min_io_size);
 377                goto failed;
 378        }
 379
 380        if (le32_to_cpu(sup->leb_size) != c->leb_size) {
 381                ubifs_err(c, "LEB size mismatch: %d in superblock, %d real",
 382                          le32_to_cpu(sup->leb_size), c->leb_size);
 383                goto failed;
 384        }
 385
 386        if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
 387            c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
 388            c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
 389            c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
 390                err = 4;
 391                goto failed;
 392        }
 393
 394        /*
 395         * Calculate minimum allowed amount of main area LEBs. This is very
 396         * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
 397         * have just read from the superblock.
 398         */
 399        min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
 400        min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;
 401
 402        if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
 403                ubifs_err(c, "bad LEB count: %d in superblock, %d on UBI volume, %d minimum required",
 404                          c->leb_cnt, c->vi.size, min_leb_cnt);
 405                goto failed;
 406        }
 407
 408        if (c->max_leb_cnt < c->leb_cnt) {
 409                ubifs_err(c, "max. LEB count %d less than LEB count %d",
 410                          c->max_leb_cnt, c->leb_cnt);
 411                goto failed;
 412        }
 413
 414        if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
 415                ubifs_err(c, "too few main LEBs count %d, must be at least %d",
 416                          c->main_lebs, UBIFS_MIN_MAIN_LEBS);
 417                goto failed;
 418        }
 419
 420        max_bytes = (long long)c->leb_size * UBIFS_MIN_BUD_LEBS;
 421        if (c->max_bud_bytes < max_bytes) {
 422                ubifs_err(c, "too small journal (%lld bytes), must be at least %lld bytes",
 423                          c->max_bud_bytes, max_bytes);
 424                goto failed;
 425        }
 426
 427        max_bytes = (long long)c->leb_size * c->main_lebs;
 428        if (c->max_bud_bytes > max_bytes) {
 429                ubifs_err(c, "too large journal size (%lld bytes), only %lld bytes available in the main area",
 430                          c->max_bud_bytes, max_bytes);
 431                goto failed;
 432        }
 433
 434        if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
 435            c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
 436                err = 9;
 437                goto failed;
 438        }
 439
 440        if (c->fanout < UBIFS_MIN_FANOUT ||
 441            ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
 442                err = 10;
 443                goto failed;
 444        }
 445
 446        if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
 447            c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
 448            c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
 449                err = 11;
 450                goto failed;
 451        }
 452
 453        if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
 454            c->orph_lebs + c->main_lebs != c->leb_cnt) {
 455                err = 12;
 456                goto failed;
 457        }
 458
 459        if (c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
 460                err = 13;
 461                goto failed;
 462        }
 463
 464        if (c->rp_size < 0 || max_bytes < c->rp_size) {
 465                err = 14;
 466                goto failed;
 467        }
 468
 469        if (le32_to_cpu(sup->time_gran) > 1000000000 ||
 470            le32_to_cpu(sup->time_gran) < 1) {
 471                err = 15;
 472                goto failed;
 473        }
 474
 475        if (!c->double_hash && c->fmt_version >= 5) {
 476                err = 16;
 477                goto failed;
 478        }
 479
 480        if (c->encrypted && c->fmt_version < 5) {
 481                err = 17;
 482                goto failed;
 483        }
 484
 485        return 0;
 486
 487failed:
 488        ubifs_err(c, "bad superblock, error %d", err);
 489        ubifs_dump_node(c, sup);
 490        return -EINVAL;
 491}
 492
 493/**
 494 * ubifs_read_sb_node - read superblock node.
 495 * @c: UBIFS file-system description object
 496 *
 497 * This function returns a pointer to the superblock node or a negative error
 498 * code. Note, the user of this function is responsible of kfree()'ing the
 499 * returned superblock buffer.
 500 */
 501struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
 502{
 503        struct ubifs_sb_node *sup;
 504        int err;
 505
 506        sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
 507        if (!sup)
 508                return ERR_PTR(-ENOMEM);
 509
 510        err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
 511                              UBIFS_SB_LNUM, 0);
 512        if (err) {
 513                kfree(sup);
 514                return ERR_PTR(err);
 515        }
 516
 517        return sup;
 518}
 519
 520/**
 521 * ubifs_write_sb_node - write superblock node.
 522 * @c: UBIFS file-system description object
 523 * @sup: superblock node read with 'ubifs_read_sb_node()'
 524 *
 525 * This function returns %0 on success and a negative error code on failure.
 526 */
 527int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
 528{
 529        int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
 530
 531        ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
 532        return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len);
 533}
 534
 535/**
 536 * ubifs_read_superblock - read superblock.
 537 * @c: UBIFS file-system description object
 538 *
 539 * This function finds, reads and checks the superblock. If an empty UBI volume
 540 * is being mounted, this function creates default superblock. Returns zero in
 541 * case of success, and a negative error code in case of failure.
 542 */
 543int ubifs_read_superblock(struct ubifs_info *c)
 544{
 545        int err, sup_flags;
 546        struct ubifs_sb_node *sup;
 547
 548        if (c->empty) {
 549                err = create_default_filesystem(c);
 550                if (err)
 551                        return err;
 552        }
 553
 554        sup = ubifs_read_sb_node(c);
 555        if (IS_ERR(sup))
 556                return PTR_ERR(sup);
 557
 558        c->fmt_version = le32_to_cpu(sup->fmt_version);
 559        c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);
 560
 561        /*
 562         * The software supports all previous versions but not future versions,
 563         * due to the unavailability of time-travelling equipment.
 564         */
 565        if (c->fmt_version > UBIFS_FORMAT_VERSION) {
 566                ubifs_assert(c, !c->ro_media || c->ro_mount);
 567                if (!c->ro_mount ||
 568                    c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
 569                        ubifs_err(c, "on-flash format version is w%d/r%d, but software only supports up to version w%d/r%d",
 570                                  c->fmt_version, c->ro_compat_version,
 571                                  UBIFS_FORMAT_VERSION,
 572                                  UBIFS_RO_COMPAT_VERSION);
 573                        if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
 574                                ubifs_msg(c, "only R/O mounting is possible");
 575                                err = -EROFS;
 576                        } else
 577                                err = -EINVAL;
 578                        goto out;
 579                }
 580
 581                /*
 582                 * The FS is mounted R/O, and the media format is
 583                 * R/O-compatible with the UBIFS implementation, so we can
 584                 * mount.
 585                 */
 586                c->rw_incompat = 1;
 587        }
 588
 589        if (c->fmt_version < 3) {
 590                ubifs_err(c, "on-flash format version %d is not supported",
 591                          c->fmt_version);
 592                err = -EINVAL;
 593                goto out;
 594        }
 595
 596        switch (sup->key_hash) {
 597        case UBIFS_KEY_HASH_R5:
 598                c->key_hash = key_r5_hash;
 599                c->key_hash_type = UBIFS_KEY_HASH_R5;
 600                break;
 601
 602        case UBIFS_KEY_HASH_TEST:
 603                c->key_hash = key_test_hash;
 604                c->key_hash_type = UBIFS_KEY_HASH_TEST;
 605                break;
 606        };
 607
 608        c->key_fmt = sup->key_fmt;
 609
 610        switch (c->key_fmt) {
 611        case UBIFS_SIMPLE_KEY_FMT:
 612                c->key_len = UBIFS_SK_LEN;
 613                break;
 614        default:
 615                ubifs_err(c, "unsupported key format");
 616                err = -EINVAL;
 617                goto out;
 618        }
 619
 620        c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
 621        c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
 622        c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
 623        c->log_lebs      = le32_to_cpu(sup->log_lebs);
 624        c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
 625        c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
 626        c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
 627        c->fanout        = le32_to_cpu(sup->fanout);
 628        c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
 629        c->rp_size       = le64_to_cpu(sup->rp_size);
 630        c->rp_uid        = make_kuid(&init_user_ns, le32_to_cpu(sup->rp_uid));
 631        c->rp_gid        = make_kgid(&init_user_ns, le32_to_cpu(sup->rp_gid));
 632        sup_flags        = le32_to_cpu(sup->flags);
 633        if (!c->mount_opts.override_compr)
 634                c->default_compr = le16_to_cpu(sup->default_compr);
 635
 636        c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
 637        memcpy(&c->uuid, &sup->uuid, 16);
 638        c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
 639        c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);
 640        c->double_hash = !!(sup_flags & UBIFS_FLG_DOUBLE_HASH);
 641        c->encrypted = !!(sup_flags & UBIFS_FLG_ENCRYPTION);
 642
 643        if ((sup_flags & ~UBIFS_FLG_MASK) != 0) {
 644                ubifs_err(c, "Unknown feature flags found: %#x",
 645                          sup_flags & ~UBIFS_FLG_MASK);
 646                err = -EINVAL;
 647                goto out;
 648        }
 649
 650#ifndef CONFIG_UBIFS_FS_ENCRYPTION
 651        if (c->encrypted) {
 652                ubifs_err(c, "file system contains encrypted files but UBIFS"
 653                             " was built without crypto support.");
 654                err = -EINVAL;
 655                goto out;
 656        }
 657#endif
 658
 659        /* Automatically increase file system size to the maximum size */
 660        c->old_leb_cnt = c->leb_cnt;
 661        if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
 662                c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
 663                if (c->ro_mount)
 664                        dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
 665                                c->old_leb_cnt, c->leb_cnt);
 666                else {
 667                        dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
 668                                c->old_leb_cnt, c->leb_cnt);
 669                        sup->leb_cnt = cpu_to_le32(c->leb_cnt);
 670                        err = ubifs_write_sb_node(c, sup);
 671                        if (err)
 672                                goto out;
 673                        c->old_leb_cnt = c->leb_cnt;
 674                }
 675        }
 676
 677        c->log_bytes = (long long)c->log_lebs * c->leb_size;
 678        c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
 679        c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
 680        c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
 681        c->orph_first = c->lpt_last + 1;
 682        c->orph_last = c->orph_first + c->orph_lebs - 1;
 683        c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
 684        c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
 685        c->main_first = c->leb_cnt - c->main_lebs;
 686
 687        err = validate_sb(c, sup);
 688out:
 689        kfree(sup);
 690        return err;
 691}
 692
 693/**
 694 * fixup_leb - fixup/unmap an LEB containing free space.
 695 * @c: UBIFS file-system description object
 696 * @lnum: the LEB number to fix up
 697 * @len: number of used bytes in LEB (starting at offset 0)
 698 *
 699 * This function reads the contents of the given LEB number @lnum, then fixes
 700 * it up, so that empty min. I/O units in the end of LEB are actually erased on
 701 * flash (rather than being just all-0xff real data). If the LEB is completely
 702 * empty, it is simply unmapped.
 703 */
 704static int fixup_leb(struct ubifs_info *c, int lnum, int len)
 705{
 706        int err;
 707
 708        ubifs_assert(c, len >= 0);
 709        ubifs_assert(c, len % c->min_io_size == 0);
 710        ubifs_assert(c, len < c->leb_size);
 711
 712        if (len == 0) {
 713                dbg_mnt("unmap empty LEB %d", lnum);
 714                return ubifs_leb_unmap(c, lnum);
 715        }
 716
 717        dbg_mnt("fixup LEB %d, data len %d", lnum, len);
 718        err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 1);
 719        if (err)
 720                return err;
 721
 722        return ubifs_leb_change(c, lnum, c->sbuf, len);
 723}
 724
 725/**
 726 * fixup_free_space - find & remap all LEBs containing free space.
 727 * @c: UBIFS file-system description object
 728 *
 729 * This function walks through all LEBs in the filesystem and fiexes up those
 730 * containing free/empty space.
 731 */
 732static int fixup_free_space(struct ubifs_info *c)
 733{
 734        int lnum, err = 0;
 735        struct ubifs_lprops *lprops;
 736
 737        ubifs_get_lprops(c);
 738
 739        /* Fixup LEBs in the master area */
 740        for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {
 741                err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);
 742                if (err)
 743                        goto out;
 744        }
 745
 746        /* Unmap unused log LEBs */
 747        lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
 748        while (lnum != c->ltail_lnum) {
 749                err = fixup_leb(c, lnum, 0);
 750                if (err)
 751                        goto out;
 752                lnum = ubifs_next_log_lnum(c, lnum);
 753        }
 754
 755        /*
 756         * Fixup the log head which contains the only a CS node at the
 757         * beginning.
 758         */
 759        err = fixup_leb(c, c->lhead_lnum,
 760                        ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size));
 761        if (err)
 762                goto out;
 763
 764        /* Fixup LEBs in the LPT area */
 765        for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
 766                int free = c->ltab[lnum - c->lpt_first].free;
 767
 768                if (free > 0) {
 769                        err = fixup_leb(c, lnum, c->leb_size - free);
 770                        if (err)
 771                                goto out;
 772                }
 773        }
 774
 775        /* Unmap LEBs in the orphans area */
 776        for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
 777                err = fixup_leb(c, lnum, 0);
 778                if (err)
 779                        goto out;
 780        }
 781
 782        /* Fixup LEBs in the main area */
 783        for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {
 784                lprops = ubifs_lpt_lookup(c, lnum);
 785                if (IS_ERR(lprops)) {
 786                        err = PTR_ERR(lprops);
 787                        goto out;
 788                }
 789
 790                if (lprops->free > 0) {
 791                        err = fixup_leb(c, lnum, c->leb_size - lprops->free);
 792                        if (err)
 793                                goto out;
 794                }
 795        }
 796
 797out:
 798        ubifs_release_lprops(c);
 799        return err;
 800}
 801
 802/**
 803 * ubifs_fixup_free_space - find & fix all LEBs with free space.
 804 * @c: UBIFS file-system description object
 805 *
 806 * This function fixes up LEBs containing free space on first mount, if the
 807 * appropriate flag was set when the FS was created. Each LEB with one or more
 808 * empty min. I/O unit (i.e. free-space-count > 0) is re-written, to make sure
 809 * the free space is actually erased. E.g., this is necessary for some NAND
 810 * chips, since the free space may have been programmed like real "0xff" data
 811 * (generating a non-0xff ECC), causing future writes to the not-really-erased
 812 * NAND pages to behave badly. After the space is fixed up, the superblock flag
 813 * is cleared, so that this is skipped for all future mounts.
 814 */
 815int ubifs_fixup_free_space(struct ubifs_info *c)
 816{
 817        int err;
 818        struct ubifs_sb_node *sup;
 819
 820        ubifs_assert(c, c->space_fixup);
 821        ubifs_assert(c, !c->ro_mount);
 822
 823        ubifs_msg(c, "start fixing up free space");
 824
 825        err = fixup_free_space(c);
 826        if (err)
 827                return err;
 828
 829        sup = ubifs_read_sb_node(c);
 830        if (IS_ERR(sup))
 831                return PTR_ERR(sup);
 832
 833        /* Free-space fixup is no longer required */
 834        c->space_fixup = 0;
 835        sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
 836
 837        err = ubifs_write_sb_node(c, sup);
 838        kfree(sup);
 839        if (err)
 840                return err;
 841
 842        ubifs_msg(c, "free space fixup complete");
 843        return err;
 844}
 845
 846int ubifs_enable_encryption(struct ubifs_info *c)
 847{
 848        int err;
 849        struct ubifs_sb_node *sup;
 850
 851        if (c->encrypted)
 852                return 0;
 853
 854        if (c->ro_mount || c->ro_media)
 855                return -EROFS;
 856
 857        if (c->fmt_version < 5) {
 858                ubifs_err(c, "on-flash format version 5 is needed for encryption");
 859                return -EINVAL;
 860        }
 861
 862        sup = ubifs_read_sb_node(c);
 863        if (IS_ERR(sup))
 864                return PTR_ERR(sup);
 865
 866        sup->flags |= cpu_to_le32(UBIFS_FLG_ENCRYPTION);
 867
 868        err = ubifs_write_sb_node(c, sup);
 869        if (!err)
 870                c->encrypted = 1;
 871        kfree(sup);
 872
 873        return err;
 874}
 875