linux/fs/ubifs/io.c
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   1/*
   2 * This file is part of UBIFS.
   3 *
   4 * Copyright (C) 2006-2008 Nokia Corporation.
   5 * Copyright (C) 2006, 2007 University of Szeged, Hungary
   6 *
   7 * This program is free software; you can redistribute it and/or modify it
   8 * under the terms of the GNU General Public License version 2 as published by
   9 * the Free Software Foundation.
  10 *
  11 * This program is distributed in the hope that it will be useful, but WITHOUT
  12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14 * more details.
  15 *
  16 * You should have received a copy of the GNU General Public License along with
  17 * this program; if not, write to the Free Software Foundation, Inc., 51
  18 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19 *
  20 * Authors: Artem Bityutskiy (Битюцкий Артём)
  21 *          Adrian Hunter
  22 *          Zoltan Sogor
  23 */
  24
  25/*
  26 * This file implements UBIFS I/O subsystem which provides various I/O-related
  27 * helper functions (reading/writing/checking/validating nodes) and implements
  28 * write-buffering support. Write buffers help to save space which otherwise
  29 * would have been wasted for padding to the nearest minimal I/O unit boundary.
  30 * Instead, data first goes to the write-buffer and is flushed when the
  31 * buffer is full or when it is not used for some time (by timer). This is
  32 * similar to the mechanism is used by JFFS2.
  33 *
  34 * UBIFS distinguishes between minimum write size (@c->min_io_size) and maximum
  35 * write size (@c->max_write_size). The latter is the maximum amount of bytes
  36 * the underlying flash is able to program at a time, and writing in
  37 * @c->max_write_size units should presumably be faster. Obviously,
  38 * @c->min_io_size <= @c->max_write_size. Write-buffers are of
  39 * @c->max_write_size bytes in size for maximum performance. However, when a
  40 * write-buffer is flushed, only the portion of it (aligned to @c->min_io_size
  41 * boundary) which contains data is written, not the whole write-buffer,
  42 * because this is more space-efficient.
  43 *
  44 * This optimization adds few complications to the code. Indeed, on the one
  45 * hand, we want to write in optimal @c->max_write_size bytes chunks, which
  46 * also means aligning writes at the @c->max_write_size bytes offsets. On the
  47 * other hand, we do not want to waste space when synchronizing the write
  48 * buffer, so during synchronization we writes in smaller chunks. And this makes
  49 * the next write offset to be not aligned to @c->max_write_size bytes. So the
  50 * have to make sure that the write-buffer offset (@wbuf->offs) becomes aligned
  51 * to @c->max_write_size bytes again. We do this by temporarily shrinking
  52 * write-buffer size (@wbuf->size).
  53 *
  54 * Write-buffers are defined by 'struct ubifs_wbuf' objects and protected by
  55 * mutexes defined inside these objects. Since sometimes upper-level code
  56 * has to lock the write-buffer (e.g. journal space reservation code), many
  57 * functions related to write-buffers have "nolock" suffix which means that the
  58 * caller has to lock the write-buffer before calling this function.
  59 *
  60 * UBIFS stores nodes at 64 bit-aligned addresses. If the node length is not
  61 * aligned, UBIFS starts the next node from the aligned address, and the padded
  62 * bytes may contain any rubbish. In other words, UBIFS does not put padding
  63 * bytes in those small gaps. Common headers of nodes store real node lengths,
  64 * not aligned lengths. Indexing nodes also store real lengths in branches.
  65 *
  66 * UBIFS uses padding when it pads to the next min. I/O unit. In this case it
  67 * uses padding nodes or padding bytes, if the padding node does not fit.
  68 *
  69 * All UBIFS nodes are protected by CRC checksums and UBIFS checks CRC when
  70 * they are read from the flash media.
  71 */
  72
  73#include <linux/crc32.h>
  74#include <linux/slab.h>
  75#include "ubifs.h"
  76
  77/**
  78 * ubifs_ro_mode - switch UBIFS to read read-only mode.
  79 * @c: UBIFS file-system description object
  80 * @err: error code which is the reason of switching to R/O mode
  81 */
  82void ubifs_ro_mode(struct ubifs_info *c, int err)
  83{
  84        if (!c->ro_error) {
  85                c->ro_error = 1;
  86                c->no_chk_data_crc = 0;
  87                c->vfs_sb->s_flags |= MS_RDONLY;
  88                ubifs_warn("switched to read-only mode, error %d", err);
  89                dump_stack();
  90        }
  91}
  92
  93/*
  94 * Below are simple wrappers over UBI I/O functions which include some
  95 * additional checks and UBIFS debugging stuff. See corresponding UBI function
  96 * for more information.
  97 */
  98
  99int ubifs_leb_read(const struct ubifs_info *c, int lnum, void *buf, int offs,
 100                   int len, int even_ebadmsg)
 101{
 102        int err;
 103
 104        err = ubi_read(c->ubi, lnum, buf, offs, len);
 105        /*
 106         * In case of %-EBADMSG print the error message only if the
 107         * @even_ebadmsg is true.
 108         */
 109        if (err && (err != -EBADMSG || even_ebadmsg)) {
 110                ubifs_err("reading %d bytes from LEB %d:%d failed, error %d",
 111                          len, lnum, offs, err);
 112                dump_stack();
 113        }
 114        return err;
 115}
 116
 117int ubifs_leb_write(struct ubifs_info *c, int lnum, const void *buf, int offs,
 118                    int len)
 119{
 120        int err;
 121
 122        ubifs_assert(!c->ro_media && !c->ro_mount);
 123        if (c->ro_error)
 124                return -EROFS;
 125        if (!dbg_is_tst_rcvry(c))
 126                err = ubi_leb_write(c->ubi, lnum, buf, offs, len);
 127        else
 128                err = dbg_leb_write(c, lnum, buf, offs, len);
 129        if (err) {
 130                ubifs_err("writing %d bytes to LEB %d:%d failed, error %d",
 131                          len, lnum, offs, err);
 132                ubifs_ro_mode(c, err);
 133                dump_stack();
 134        }
 135        return err;
 136}
 137
 138int ubifs_leb_change(struct ubifs_info *c, int lnum, const void *buf, int len)
 139{
 140        int err;
 141
 142        ubifs_assert(!c->ro_media && !c->ro_mount);
 143        if (c->ro_error)
 144                return -EROFS;
 145        if (!dbg_is_tst_rcvry(c))
 146                err = ubi_leb_change(c->ubi, lnum, buf, len);
 147        else
 148                err = dbg_leb_change(c, lnum, buf, len);
 149        if (err) {
 150                ubifs_err("changing %d bytes in LEB %d failed, error %d",
 151                          len, lnum, err);
 152                ubifs_ro_mode(c, err);
 153                dump_stack();
 154        }
 155        return err;
 156}
 157
 158int ubifs_leb_unmap(struct ubifs_info *c, int lnum)
 159{
 160        int err;
 161
 162        ubifs_assert(!c->ro_media && !c->ro_mount);
 163        if (c->ro_error)
 164                return -EROFS;
 165        if (!dbg_is_tst_rcvry(c))
 166                err = ubi_leb_unmap(c->ubi, lnum);
 167        else
 168                err = dbg_leb_unmap(c, lnum);
 169        if (err) {
 170                ubifs_err("unmap LEB %d failed, error %d", lnum, err);
 171                ubifs_ro_mode(c, err);
 172                dump_stack();
 173        }
 174        return err;
 175}
 176
 177int ubifs_leb_map(struct ubifs_info *c, int lnum)
 178{
 179        int err;
 180
 181        ubifs_assert(!c->ro_media && !c->ro_mount);
 182        if (c->ro_error)
 183                return -EROFS;
 184        if (!dbg_is_tst_rcvry(c))
 185                err = ubi_leb_map(c->ubi, lnum);
 186        else
 187                err = dbg_leb_map(c, lnum);
 188        if (err) {
 189                ubifs_err("mapping LEB %d failed, error %d", lnum, err);
 190                ubifs_ro_mode(c, err);
 191                dump_stack();
 192        }
 193        return err;
 194}
 195
 196int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
 197{
 198        int err;
 199
 200        err = ubi_is_mapped(c->ubi, lnum);
 201        if (err < 0) {
 202                ubifs_err("ubi_is_mapped failed for LEB %d, error %d",
 203                          lnum, err);
 204                dump_stack();
 205        }
 206        return err;
 207}
 208
 209/**
 210 * ubifs_check_node - check node.
 211 * @c: UBIFS file-system description object
 212 * @buf: node to check
 213 * @lnum: logical eraseblock number
 214 * @offs: offset within the logical eraseblock
 215 * @quiet: print no messages
 216 * @must_chk_crc: indicates whether to always check the CRC
 217 *
 218 * This function checks node magic number and CRC checksum. This function also
 219 * validates node length to prevent UBIFS from becoming crazy when an attacker
 220 * feeds it a file-system image with incorrect nodes. For example, too large
 221 * node length in the common header could cause UBIFS to read memory outside of
 222 * allocated buffer when checking the CRC checksum.
 223 *
 224 * This function may skip data nodes CRC checking if @c->no_chk_data_crc is
 225 * true, which is controlled by corresponding UBIFS mount option. However, if
 226 * @must_chk_crc is true, then @c->no_chk_data_crc is ignored and CRC is
 227 * checked. Similarly, if @c->mounting or @c->remounting_rw is true (we are
 228 * mounting or re-mounting to R/W mode), @c->no_chk_data_crc is ignored and CRC
 229 * is checked. This is because during mounting or re-mounting from R/O mode to
 230 * R/W mode we may read journal nodes (when replying the journal or doing the
 231 * recovery) and the journal nodes may potentially be corrupted, so checking is
 232 * required.
 233 *
 234 * This function returns zero in case of success and %-EUCLEAN in case of bad
 235 * CRC or magic.
 236 */
 237int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
 238                     int offs, int quiet, int must_chk_crc)
 239{
 240        int err = -EINVAL, type, node_len;
 241        uint32_t crc, node_crc, magic;
 242        const struct ubifs_ch *ch = buf;
 243
 244        ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
 245        ubifs_assert(!(offs & 7) && offs < c->leb_size);
 246
 247        magic = le32_to_cpu(ch->magic);
 248        if (magic != UBIFS_NODE_MAGIC) {
 249                if (!quiet)
 250                        ubifs_err("bad magic %#08x, expected %#08x",
 251                                  magic, UBIFS_NODE_MAGIC);
 252                err = -EUCLEAN;
 253                goto out;
 254        }
 255
 256        type = ch->node_type;
 257        if (type < 0 || type >= UBIFS_NODE_TYPES_CNT) {
 258                if (!quiet)
 259                        ubifs_err("bad node type %d", type);
 260                goto out;
 261        }
 262
 263        node_len = le32_to_cpu(ch->len);
 264        if (node_len + offs > c->leb_size)
 265                goto out_len;
 266
 267        if (c->ranges[type].max_len == 0) {
 268                if (node_len != c->ranges[type].len)
 269                        goto out_len;
 270        } else if (node_len < c->ranges[type].min_len ||
 271                   node_len > c->ranges[type].max_len)
 272                goto out_len;
 273
 274        if (!must_chk_crc && type == UBIFS_DATA_NODE && !c->mounting &&
 275            !c->remounting_rw && c->no_chk_data_crc)
 276                return 0;
 277
 278        crc = crc32(UBIFS_CRC32_INIT, buf + 8, node_len - 8);
 279        node_crc = le32_to_cpu(ch->crc);
 280        if (crc != node_crc) {
 281                if (!quiet)
 282                        ubifs_err("bad CRC: calculated %#08x, read %#08x",
 283                                  crc, node_crc);
 284                err = -EUCLEAN;
 285                goto out;
 286        }
 287
 288        return 0;
 289
 290out_len:
 291        if (!quiet)
 292                ubifs_err("bad node length %d", node_len);
 293out:
 294        if (!quiet) {
 295                ubifs_err("bad node at LEB %d:%d", lnum, offs);
 296                ubifs_dump_node(c, buf);
 297                dump_stack();
 298        }
 299        return err;
 300}
 301
 302/**
 303 * ubifs_pad - pad flash space.
 304 * @c: UBIFS file-system description object
 305 * @buf: buffer to put padding to
 306 * @pad: how many bytes to pad
 307 *
 308 * The flash media obliges us to write only in chunks of %c->min_io_size and
 309 * when we have to write less data we add padding node to the write-buffer and
 310 * pad it to the next minimal I/O unit's boundary. Padding nodes help when the
 311 * media is being scanned. If the amount of wasted space is not enough to fit a
 312 * padding node which takes %UBIFS_PAD_NODE_SZ bytes, we write padding bytes
 313 * pattern (%UBIFS_PADDING_BYTE).
 314 *
 315 * Padding nodes are also used to fill gaps when the "commit-in-gaps" method is
 316 * used.
 317 */
 318void ubifs_pad(const struct ubifs_info *c, void *buf, int pad)
 319{
 320        uint32_t crc;
 321
 322        ubifs_assert(pad >= 0 && !(pad & 7));
 323
 324        if (pad >= UBIFS_PAD_NODE_SZ) {
 325                struct ubifs_ch *ch = buf;
 326                struct ubifs_pad_node *pad_node = buf;
 327
 328                ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
 329                ch->node_type = UBIFS_PAD_NODE;
 330                ch->group_type = UBIFS_NO_NODE_GROUP;
 331                ch->padding[0] = ch->padding[1] = 0;
 332                ch->sqnum = 0;
 333                ch->len = cpu_to_le32(UBIFS_PAD_NODE_SZ);
 334                pad -= UBIFS_PAD_NODE_SZ;
 335                pad_node->pad_len = cpu_to_le32(pad);
 336                crc = crc32(UBIFS_CRC32_INIT, buf + 8, UBIFS_PAD_NODE_SZ - 8);
 337                ch->crc = cpu_to_le32(crc);
 338                memset(buf + UBIFS_PAD_NODE_SZ, 0, pad);
 339        } else if (pad > 0)
 340                /* Too little space, padding node won't fit */
 341                memset(buf, UBIFS_PADDING_BYTE, pad);
 342}
 343
 344/**
 345 * next_sqnum - get next sequence number.
 346 * @c: UBIFS file-system description object
 347 */
 348static unsigned long long next_sqnum(struct ubifs_info *c)
 349{
 350        unsigned long long sqnum;
 351
 352        spin_lock(&c->cnt_lock);
 353        sqnum = ++c->max_sqnum;
 354        spin_unlock(&c->cnt_lock);
 355
 356        if (unlikely(sqnum >= SQNUM_WARN_WATERMARK)) {
 357                if (sqnum >= SQNUM_WATERMARK) {
 358                        ubifs_err("sequence number overflow %llu, end of life",
 359                                  sqnum);
 360                        ubifs_ro_mode(c, -EINVAL);
 361                }
 362                ubifs_warn("running out of sequence numbers, end of life soon");
 363        }
 364
 365        return sqnum;
 366}
 367
 368/**
 369 * ubifs_prepare_node - prepare node to be written to flash.
 370 * @c: UBIFS file-system description object
 371 * @node: the node to pad
 372 * @len: node length
 373 * @pad: if the buffer has to be padded
 374 *
 375 * This function prepares node at @node to be written to the media - it
 376 * calculates node CRC, fills the common header, and adds proper padding up to
 377 * the next minimum I/O unit if @pad is not zero.
 378 */
 379void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
 380{
 381        uint32_t crc;
 382        struct ubifs_ch *ch = node;
 383        unsigned long long sqnum = next_sqnum(c);
 384
 385        ubifs_assert(len >= UBIFS_CH_SZ);
 386
 387        ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
 388        ch->len = cpu_to_le32(len);
 389        ch->group_type = UBIFS_NO_NODE_GROUP;
 390        ch->sqnum = cpu_to_le64(sqnum);
 391        ch->padding[0] = ch->padding[1] = 0;
 392        crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
 393        ch->crc = cpu_to_le32(crc);
 394
 395        if (pad) {
 396                len = ALIGN(len, 8);
 397                pad = ALIGN(len, c->min_io_size) - len;
 398                ubifs_pad(c, node + len, pad);
 399        }
 400}
 401
 402/**
 403 * ubifs_prep_grp_node - prepare node of a group to be written to flash.
 404 * @c: UBIFS file-system description object
 405 * @node: the node to pad
 406 * @len: node length
 407 * @last: indicates the last node of the group
 408 *
 409 * This function prepares node at @node to be written to the media - it
 410 * calculates node CRC and fills the common header.
 411 */
 412void ubifs_prep_grp_node(struct ubifs_info *c, void *node, int len, int last)
 413{
 414        uint32_t crc;
 415        struct ubifs_ch *ch = node;
 416        unsigned long long sqnum = next_sqnum(c);
 417
 418        ubifs_assert(len >= UBIFS_CH_SZ);
 419
 420        ch->magic = cpu_to_le32(UBIFS_NODE_MAGIC);
 421        ch->len = cpu_to_le32(len);
 422        if (last)
 423                ch->group_type = UBIFS_LAST_OF_NODE_GROUP;
 424        else
 425                ch->group_type = UBIFS_IN_NODE_GROUP;
 426        ch->sqnum = cpu_to_le64(sqnum);
 427        ch->padding[0] = ch->padding[1] = 0;
 428        crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
 429        ch->crc = cpu_to_le32(crc);
 430}
 431
 432/**
 433 * wbuf_timer_callback - write-buffer timer callback function.
 434 * @data: timer data (write-buffer descriptor)
 435 *
 436 * This function is called when the write-buffer timer expires.
 437 */
 438static enum hrtimer_restart wbuf_timer_callback_nolock(struct hrtimer *timer)
 439{
 440        struct ubifs_wbuf *wbuf = container_of(timer, struct ubifs_wbuf, timer);
 441
 442        dbg_io("jhead %s", dbg_jhead(wbuf->jhead));
 443        wbuf->need_sync = 1;
 444        wbuf->c->need_wbuf_sync = 1;
 445        ubifs_wake_up_bgt(wbuf->c);
 446        return HRTIMER_NORESTART;
 447}
 448
 449/**
 450 * new_wbuf_timer - start new write-buffer timer.
 451 * @wbuf: write-buffer descriptor
 452 */
 453static void new_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
 454{
 455        ubifs_assert(!hrtimer_active(&wbuf->timer));
 456
 457        if (wbuf->no_timer)
 458                return;
 459        dbg_io("set timer for jhead %s, %llu-%llu millisecs",
 460               dbg_jhead(wbuf->jhead),
 461               div_u64(ktime_to_ns(wbuf->softlimit), USEC_PER_SEC),
 462               div_u64(ktime_to_ns(wbuf->softlimit) + wbuf->delta,
 463                       USEC_PER_SEC));
 464        hrtimer_start_range_ns(&wbuf->timer, wbuf->softlimit, wbuf->delta,
 465                               HRTIMER_MODE_REL);
 466}
 467
 468/**
 469 * cancel_wbuf_timer - cancel write-buffer timer.
 470 * @wbuf: write-buffer descriptor
 471 */
 472static void cancel_wbuf_timer_nolock(struct ubifs_wbuf *wbuf)
 473{
 474        if (wbuf->no_timer)
 475                return;
 476        wbuf->need_sync = 0;
 477        hrtimer_cancel(&wbuf->timer);
 478}
 479
 480/**
 481 * ubifs_wbuf_sync_nolock - synchronize write-buffer.
 482 * @wbuf: write-buffer to synchronize
 483 *
 484 * This function synchronizes write-buffer @buf and returns zero in case of
 485 * success or a negative error code in case of failure.
 486 *
 487 * Note, although write-buffers are of @c->max_write_size, this function does
 488 * not necessarily writes all @c->max_write_size bytes to the flash. Instead,
 489 * if the write-buffer is only partially filled with data, only the used part
 490 * of the write-buffer (aligned on @c->min_io_size boundary) is synchronized.
 491 * This way we waste less space.
 492 */
 493int ubifs_wbuf_sync_nolock(struct ubifs_wbuf *wbuf)
 494{
 495        struct ubifs_info *c = wbuf->c;
 496        int err, dirt, sync_len;
 497
 498        cancel_wbuf_timer_nolock(wbuf);
 499        if (!wbuf->used || wbuf->lnum == -1)
 500                /* Write-buffer is empty or not seeked */
 501                return 0;
 502
 503        dbg_io("LEB %d:%d, %d bytes, jhead %s",
 504               wbuf->lnum, wbuf->offs, wbuf->used, dbg_jhead(wbuf->jhead));
 505        ubifs_assert(!(wbuf->avail & 7));
 506        ubifs_assert(wbuf->offs + wbuf->size <= c->leb_size);
 507        ubifs_assert(wbuf->size >= c->min_io_size);
 508        ubifs_assert(wbuf->size <= c->max_write_size);
 509        ubifs_assert(wbuf->size % c->min_io_size == 0);
 510        ubifs_assert(!c->ro_media && !c->ro_mount);
 511        if (c->leb_size - wbuf->offs >= c->max_write_size)
 512                ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
 513
 514        if (c->ro_error)
 515                return -EROFS;
 516
 517        /*
 518         * Do not write whole write buffer but write only the minimum necessary
 519         * amount of min. I/O units.
 520         */
 521        sync_len = ALIGN(wbuf->used, c->min_io_size);
 522        dirt = sync_len - wbuf->used;
 523        if (dirt)
 524                ubifs_pad(c, wbuf->buf + wbuf->used, dirt);
 525        err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, sync_len);
 526        if (err)
 527                return err;
 528
 529        spin_lock(&wbuf->lock);
 530        wbuf->offs += sync_len;
 531        /*
 532         * Now @wbuf->offs is not necessarily aligned to @c->max_write_size.
 533         * But our goal is to optimize writes and make sure we write in
 534         * @c->max_write_size chunks and to @c->max_write_size-aligned offset.
 535         * Thus, if @wbuf->offs is not aligned to @c->max_write_size now, make
 536         * sure that @wbuf->offs + @wbuf->size is aligned to
 537         * @c->max_write_size. This way we make sure that after next
 538         * write-buffer flush we are again at the optimal offset (aligned to
 539         * @c->max_write_size).
 540         */
 541        if (c->leb_size - wbuf->offs < c->max_write_size)
 542                wbuf->size = c->leb_size - wbuf->offs;
 543        else if (wbuf->offs & (c->max_write_size - 1))
 544                wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
 545        else
 546                wbuf->size = c->max_write_size;
 547        wbuf->avail = wbuf->size;
 548        wbuf->used = 0;
 549        wbuf->next_ino = 0;
 550        spin_unlock(&wbuf->lock);
 551
 552        if (wbuf->sync_callback)
 553                err = wbuf->sync_callback(c, wbuf->lnum,
 554                                          c->leb_size - wbuf->offs, dirt);
 555        return err;
 556}
 557
 558/**
 559 * ubifs_wbuf_seek_nolock - seek write-buffer.
 560 * @wbuf: write-buffer
 561 * @lnum: logical eraseblock number to seek to
 562 * @offs: logical eraseblock offset to seek to
 563 *
 564 * This function targets the write-buffer to logical eraseblock @lnum:@offs.
 565 * The write-buffer has to be empty. Returns zero in case of success and a
 566 * negative error code in case of failure.
 567 */
 568int ubifs_wbuf_seek_nolock(struct ubifs_wbuf *wbuf, int lnum, int offs)
 569{
 570        const struct ubifs_info *c = wbuf->c;
 571
 572        dbg_io("LEB %d:%d, jhead %s", lnum, offs, dbg_jhead(wbuf->jhead));
 573        ubifs_assert(lnum >= 0 && lnum < c->leb_cnt);
 574        ubifs_assert(offs >= 0 && offs <= c->leb_size);
 575        ubifs_assert(offs % c->min_io_size == 0 && !(offs & 7));
 576        ubifs_assert(lnum != wbuf->lnum);
 577        ubifs_assert(wbuf->used == 0);
 578
 579        spin_lock(&wbuf->lock);
 580        wbuf->lnum = lnum;
 581        wbuf->offs = offs;
 582        if (c->leb_size - wbuf->offs < c->max_write_size)
 583                wbuf->size = c->leb_size - wbuf->offs;
 584        else if (wbuf->offs & (c->max_write_size - 1))
 585                wbuf->size = ALIGN(wbuf->offs, c->max_write_size) - wbuf->offs;
 586        else
 587                wbuf->size = c->max_write_size;
 588        wbuf->avail = wbuf->size;
 589        wbuf->used = 0;
 590        spin_unlock(&wbuf->lock);
 591
 592        return 0;
 593}
 594
 595/**
 596 * ubifs_bg_wbufs_sync - synchronize write-buffers.
 597 * @c: UBIFS file-system description object
 598 *
 599 * This function is called by background thread to synchronize write-buffers.
 600 * Returns zero in case of success and a negative error code in case of
 601 * failure.
 602 */
 603int ubifs_bg_wbufs_sync(struct ubifs_info *c)
 604{
 605        int err, i;
 606
 607        ubifs_assert(!c->ro_media && !c->ro_mount);
 608        if (!c->need_wbuf_sync)
 609                return 0;
 610        c->need_wbuf_sync = 0;
 611
 612        if (c->ro_error) {
 613                err = -EROFS;
 614                goto out_timers;
 615        }
 616
 617        dbg_io("synchronize");
 618        for (i = 0; i < c->jhead_cnt; i++) {
 619                struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
 620
 621                cond_resched();
 622
 623                /*
 624                 * If the mutex is locked then wbuf is being changed, so
 625                 * synchronization is not necessary.
 626                 */
 627                if (mutex_is_locked(&wbuf->io_mutex))
 628                        continue;
 629
 630                mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
 631                if (!wbuf->need_sync) {
 632                        mutex_unlock(&wbuf->io_mutex);
 633                        continue;
 634                }
 635
 636                err = ubifs_wbuf_sync_nolock(wbuf);
 637                mutex_unlock(&wbuf->io_mutex);
 638                if (err) {
 639                        ubifs_err("cannot sync write-buffer, error %d", err);
 640                        ubifs_ro_mode(c, err);
 641                        goto out_timers;
 642                }
 643        }
 644
 645        return 0;
 646
 647out_timers:
 648        /* Cancel all timers to prevent repeated errors */
 649        for (i = 0; i < c->jhead_cnt; i++) {
 650                struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
 651
 652                mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
 653                cancel_wbuf_timer_nolock(wbuf);
 654                mutex_unlock(&wbuf->io_mutex);
 655        }
 656        return err;
 657}
 658
 659/**
 660 * ubifs_wbuf_write_nolock - write data to flash via write-buffer.
 661 * @wbuf: write-buffer
 662 * @buf: node to write
 663 * @len: node length
 664 *
 665 * This function writes data to flash via write-buffer @wbuf. This means that
 666 * the last piece of the node won't reach the flash media immediately if it
 667 * does not take whole max. write unit (@c->max_write_size). Instead, the node
 668 * will sit in RAM until the write-buffer is synchronized (e.g., by timer, or
 669 * because more data are appended to the write-buffer).
 670 *
 671 * This function returns zero in case of success and a negative error code in
 672 * case of failure. If the node cannot be written because there is no more
 673 * space in this logical eraseblock, %-ENOSPC is returned.
 674 */
 675int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
 676{
 677        struct ubifs_info *c = wbuf->c;
 678        int err, written, n, aligned_len = ALIGN(len, 8);
 679
 680        dbg_io("%d bytes (%s) to jhead %s wbuf at LEB %d:%d", len,
 681               dbg_ntype(((struct ubifs_ch *)buf)->node_type),
 682               dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs + wbuf->used);
 683        ubifs_assert(len > 0 && wbuf->lnum >= 0 && wbuf->lnum < c->leb_cnt);
 684        ubifs_assert(wbuf->offs >= 0 && wbuf->offs % c->min_io_size == 0);
 685        ubifs_assert(!(wbuf->offs & 7) && wbuf->offs <= c->leb_size);
 686        ubifs_assert(wbuf->avail > 0 && wbuf->avail <= wbuf->size);
 687        ubifs_assert(wbuf->size >= c->min_io_size);
 688        ubifs_assert(wbuf->size <= c->max_write_size);
 689        ubifs_assert(wbuf->size % c->min_io_size == 0);
 690        ubifs_assert(mutex_is_locked(&wbuf->io_mutex));
 691        ubifs_assert(!c->ro_media && !c->ro_mount);
 692        ubifs_assert(!c->space_fixup);
 693        if (c->leb_size - wbuf->offs >= c->max_write_size)
 694                ubifs_assert(!((wbuf->offs + wbuf->size) % c->max_write_size));
 695
 696        if (c->leb_size - wbuf->offs - wbuf->used < aligned_len) {
 697                err = -ENOSPC;
 698                goto out;
 699        }
 700
 701        cancel_wbuf_timer_nolock(wbuf);
 702
 703        if (c->ro_error)
 704                return -EROFS;
 705
 706        if (aligned_len <= wbuf->avail) {
 707                /*
 708                 * The node is not very large and fits entirely within
 709                 * write-buffer.
 710                 */
 711                memcpy(wbuf->buf + wbuf->used, buf, len);
 712
 713                if (aligned_len == wbuf->avail) {
 714                        dbg_io("flush jhead %s wbuf to LEB %d:%d",
 715                               dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
 716                        err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf,
 717                                              wbuf->offs, wbuf->size);
 718                        if (err)
 719                                goto out;
 720
 721                        spin_lock(&wbuf->lock);
 722                        wbuf->offs += wbuf->size;
 723                        if (c->leb_size - wbuf->offs >= c->max_write_size)
 724                                wbuf->size = c->max_write_size;
 725                        else
 726                                wbuf->size = c->leb_size - wbuf->offs;
 727                        wbuf->avail = wbuf->size;
 728                        wbuf->used = 0;
 729                        wbuf->next_ino = 0;
 730                        spin_unlock(&wbuf->lock);
 731                } else {
 732                        spin_lock(&wbuf->lock);
 733                        wbuf->avail -= aligned_len;
 734                        wbuf->used += aligned_len;
 735                        spin_unlock(&wbuf->lock);
 736                }
 737
 738                goto exit;
 739        }
 740
 741        written = 0;
 742
 743        if (wbuf->used) {
 744                /*
 745                 * The node is large enough and does not fit entirely within
 746                 * current available space. We have to fill and flush
 747                 * write-buffer and switch to the next max. write unit.
 748                 */
 749                dbg_io("flush jhead %s wbuf to LEB %d:%d",
 750                       dbg_jhead(wbuf->jhead), wbuf->lnum, wbuf->offs);
 751                memcpy(wbuf->buf + wbuf->used, buf, wbuf->avail);
 752                err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs,
 753                                      wbuf->size);
 754                if (err)
 755                        goto out;
 756
 757                wbuf->offs += wbuf->size;
 758                len -= wbuf->avail;
 759                aligned_len -= wbuf->avail;
 760                written += wbuf->avail;
 761        } else if (wbuf->offs & (c->max_write_size - 1)) {
 762                /*
 763                 * The write-buffer offset is not aligned to
 764                 * @c->max_write_size and @wbuf->size is less than
 765                 * @c->max_write_size. Write @wbuf->size bytes to make sure the
 766                 * following writes are done in optimal @c->max_write_size
 767                 * chunks.
 768                 */
 769                dbg_io("write %d bytes to LEB %d:%d",
 770                       wbuf->size, wbuf->lnum, wbuf->offs);
 771                err = ubifs_leb_write(c, wbuf->lnum, buf, wbuf->offs,
 772                                      wbuf->size);
 773                if (err)
 774                        goto out;
 775
 776                wbuf->offs += wbuf->size;
 777                len -= wbuf->size;
 778                aligned_len -= wbuf->size;
 779                written += wbuf->size;
 780        }
 781
 782        /*
 783         * The remaining data may take more whole max. write units, so write the
 784         * remains multiple to max. write unit size directly to the flash media.
 785         * We align node length to 8-byte boundary because we anyway flash wbuf
 786         * if the remaining space is less than 8 bytes.
 787         */
 788        n = aligned_len >> c->max_write_shift;
 789        if (n) {
 790                n <<= c->max_write_shift;
 791                dbg_io("write %d bytes to LEB %d:%d", n, wbuf->lnum,
 792                       wbuf->offs);
 793                err = ubifs_leb_write(c, wbuf->lnum, buf + written,
 794                                      wbuf->offs, n);
 795                if (err)
 796                        goto out;
 797                wbuf->offs += n;
 798                aligned_len -= n;
 799                len -= n;
 800                written += n;
 801        }
 802
 803        spin_lock(&wbuf->lock);
 804        if (aligned_len)
 805                /*
 806                 * And now we have what's left and what does not take whole
 807                 * max. write unit, so write it to the write-buffer and we are
 808                 * done.
 809                 */
 810                memcpy(wbuf->buf, buf + written, len);
 811
 812        if (c->leb_size - wbuf->offs >= c->max_write_size)
 813                wbuf->size = c->max_write_size;
 814        else
 815                wbuf->size = c->leb_size - wbuf->offs;
 816        wbuf->avail = wbuf->size - aligned_len;
 817        wbuf->used = aligned_len;
 818        wbuf->next_ino = 0;
 819        spin_unlock(&wbuf->lock);
 820
 821exit:
 822        if (wbuf->sync_callback) {
 823                int free = c->leb_size - wbuf->offs - wbuf->used;
 824
 825                err = wbuf->sync_callback(c, wbuf->lnum, free, 0);
 826                if (err)
 827                        goto out;
 828        }
 829
 830        if (wbuf->used)
 831                new_wbuf_timer_nolock(wbuf);
 832
 833        return 0;
 834
 835out:
 836        ubifs_err("cannot write %d bytes to LEB %d:%d, error %d",
 837                  len, wbuf->lnum, wbuf->offs, err);
 838        ubifs_dump_node(c, buf);
 839        dump_stack();
 840        ubifs_dump_leb(c, wbuf->lnum);
 841        return err;
 842}
 843
 844/**
 845 * ubifs_write_node - write node to the media.
 846 * @c: UBIFS file-system description object
 847 * @buf: the node to write
 848 * @len: node length
 849 * @lnum: logical eraseblock number
 850 * @offs: offset within the logical eraseblock
 851 *
 852 * This function automatically fills node magic number, assigns sequence
 853 * number, and calculates node CRC checksum. The length of the @buf buffer has
 854 * to be aligned to the minimal I/O unit size. This function automatically
 855 * appends padding node and padding bytes if needed. Returns zero in case of
 856 * success and a negative error code in case of failure.
 857 */
 858int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
 859                     int offs)
 860{
 861        int err, buf_len = ALIGN(len, c->min_io_size);
 862
 863        dbg_io("LEB %d:%d, %s, length %d (aligned %d)",
 864               lnum, offs, dbg_ntype(((struct ubifs_ch *)buf)->node_type), len,
 865               buf_len);
 866        ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
 867        ubifs_assert(offs % c->min_io_size == 0 && offs < c->leb_size);
 868        ubifs_assert(!c->ro_media && !c->ro_mount);
 869        ubifs_assert(!c->space_fixup);
 870
 871        if (c->ro_error)
 872                return -EROFS;
 873
 874        ubifs_prepare_node(c, buf, len, 1);
 875        err = ubifs_leb_write(c, lnum, buf, offs, buf_len);
 876        if (err)
 877                ubifs_dump_node(c, buf);
 878
 879        return err;
 880}
 881
 882/**
 883 * ubifs_read_node_wbuf - read node from the media or write-buffer.
 884 * @wbuf: wbuf to check for un-written data
 885 * @buf: buffer to read to
 886 * @type: node type
 887 * @len: node length
 888 * @lnum: logical eraseblock number
 889 * @offs: offset within the logical eraseblock
 890 *
 891 * This function reads a node of known type and length, checks it and stores
 892 * in @buf. If the node partially or fully sits in the write-buffer, this
 893 * function takes data from the buffer, otherwise it reads the flash media.
 894 * Returns zero in case of success, %-EUCLEAN if CRC mismatched and a negative
 895 * error code in case of failure.
 896 */
 897int ubifs_read_node_wbuf(struct ubifs_wbuf *wbuf, void *buf, int type, int len,
 898                         int lnum, int offs)
 899{
 900        const struct ubifs_info *c = wbuf->c;
 901        int err, rlen, overlap;
 902        struct ubifs_ch *ch = buf;
 903
 904        dbg_io("LEB %d:%d, %s, length %d, jhead %s", lnum, offs,
 905               dbg_ntype(type), len, dbg_jhead(wbuf->jhead));
 906        ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
 907        ubifs_assert(!(offs & 7) && offs < c->leb_size);
 908        ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
 909
 910        spin_lock(&wbuf->lock);
 911        overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
 912        if (!overlap) {
 913                /* We may safely unlock the write-buffer and read the data */
 914                spin_unlock(&wbuf->lock);
 915                return ubifs_read_node(c, buf, type, len, lnum, offs);
 916        }
 917
 918        /* Don't read under wbuf */
 919        rlen = wbuf->offs - offs;
 920        if (rlen < 0)
 921                rlen = 0;
 922
 923        /* Copy the rest from the write-buffer */
 924        memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
 925        spin_unlock(&wbuf->lock);
 926
 927        if (rlen > 0) {
 928                /* Read everything that goes before write-buffer */
 929                err = ubifs_leb_read(c, lnum, buf, offs, rlen, 0);
 930                if (err && err != -EBADMSG)
 931                        return err;
 932        }
 933
 934        if (type != ch->node_type) {
 935                ubifs_err("bad node type (%d but expected %d)",
 936                          ch->node_type, type);
 937                goto out;
 938        }
 939
 940        err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
 941        if (err) {
 942                ubifs_err("expected node type %d", type);
 943                return err;
 944        }
 945
 946        rlen = le32_to_cpu(ch->len);
 947        if (rlen != len) {
 948                ubifs_err("bad node length %d, expected %d", rlen, len);
 949                goto out;
 950        }
 951
 952        return 0;
 953
 954out:
 955        ubifs_err("bad node at LEB %d:%d", lnum, offs);
 956        ubifs_dump_node(c, buf);
 957        dump_stack();
 958        return -EINVAL;
 959}
 960
 961/**
 962 * ubifs_read_node - read node.
 963 * @c: UBIFS file-system description object
 964 * @buf: buffer to read to
 965 * @type: node type
 966 * @len: node length (not aligned)
 967 * @lnum: logical eraseblock number
 968 * @offs: offset within the logical eraseblock
 969 *
 970 * This function reads a node of known type and and length, checks it and
 971 * stores in @buf. Returns zero in case of success, %-EUCLEAN if CRC mismatched
 972 * and a negative error code in case of failure.
 973 */
 974int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
 975                    int lnum, int offs)
 976{
 977        int err, l;
 978        struct ubifs_ch *ch = buf;
 979
 980        dbg_io("LEB %d:%d, %s, length %d", lnum, offs, dbg_ntype(type), len);
 981        ubifs_assert(lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
 982        ubifs_assert(len >= UBIFS_CH_SZ && offs + len <= c->leb_size);
 983        ubifs_assert(!(offs & 7) && offs < c->leb_size);
 984        ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
 985
 986        err = ubifs_leb_read(c, lnum, buf, offs, len, 0);
 987        if (err && err != -EBADMSG)
 988                return err;
 989
 990        if (type != ch->node_type) {
 991                ubifs_err("bad node type (%d but expected %d)",
 992                          ch->node_type, type);
 993                goto out;
 994        }
 995
 996        err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
 997        if (err) {
 998                ubifs_err("expected node type %d", type);
 999                return err;
1000        }
1001
1002        l = le32_to_cpu(ch->len);
1003        if (l != len) {
1004                ubifs_err("bad node length %d, expected %d", l, len);
1005                goto out;
1006        }
1007
1008        return 0;
1009
1010out:
1011        ubifs_err("bad node at LEB %d:%d, LEB mapping status %d", lnum, offs,
1012                  ubi_is_mapped(c->ubi, lnum));
1013        ubifs_dump_node(c, buf);
1014        dump_stack();
1015        return -EINVAL;
1016}
1017
1018/**
1019 * ubifs_wbuf_init - initialize write-buffer.
1020 * @c: UBIFS file-system description object
1021 * @wbuf: write-buffer to initialize
1022 *
1023 * This function initializes write-buffer. Returns zero in case of success
1024 * %-ENOMEM in case of failure.
1025 */
1026int ubifs_wbuf_init(struct ubifs_info *c, struct ubifs_wbuf *wbuf)
1027{
1028        size_t size;
1029
1030        wbuf->buf = kmalloc(c->max_write_size, GFP_KERNEL);
1031        if (!wbuf->buf)
1032                return -ENOMEM;
1033
1034        size = (c->max_write_size / UBIFS_CH_SZ + 1) * sizeof(ino_t);
1035        wbuf->inodes = kmalloc(size, GFP_KERNEL);
1036        if (!wbuf->inodes) {
1037                kfree(wbuf->buf);
1038                wbuf->buf = NULL;
1039                return -ENOMEM;
1040        }
1041
1042        wbuf->used = 0;
1043        wbuf->lnum = wbuf->offs = -1;
1044        /*
1045         * If the LEB starts at the max. write size aligned address, then
1046         * write-buffer size has to be set to @c->max_write_size. Otherwise,
1047         * set it to something smaller so that it ends at the closest max.
1048         * write size boundary.
1049         */
1050        size = c->max_write_size - (c->leb_start % c->max_write_size);
1051        wbuf->avail = wbuf->size = size;
1052        wbuf->sync_callback = NULL;
1053        mutex_init(&wbuf->io_mutex);
1054        spin_lock_init(&wbuf->lock);
1055        wbuf->c = c;
1056        wbuf->next_ino = 0;
1057
1058        hrtimer_init(&wbuf->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1059        wbuf->timer.function = wbuf_timer_callback_nolock;
1060        wbuf->softlimit = ktime_set(WBUF_TIMEOUT_SOFTLIMIT, 0);
1061        wbuf->delta = WBUF_TIMEOUT_HARDLIMIT - WBUF_TIMEOUT_SOFTLIMIT;
1062        wbuf->delta *= 1000000000ULL;
1063        ubifs_assert(wbuf->delta <= ULONG_MAX);
1064        return 0;
1065}
1066
1067/**
1068 * ubifs_wbuf_add_ino_nolock - add an inode number into the wbuf inode array.
1069 * @wbuf: the write-buffer where to add
1070 * @inum: the inode number
1071 *
1072 * This function adds an inode number to the inode array of the write-buffer.
1073 */
1074void ubifs_wbuf_add_ino_nolock(struct ubifs_wbuf *wbuf, ino_t inum)
1075{
1076        if (!wbuf->buf)
1077                /* NOR flash or something similar */
1078                return;
1079
1080        spin_lock(&wbuf->lock);
1081        if (wbuf->used)
1082                wbuf->inodes[wbuf->next_ino++] = inum;
1083        spin_unlock(&wbuf->lock);
1084}
1085
1086/**
1087 * wbuf_has_ino - returns if the wbuf contains data from the inode.
1088 * @wbuf: the write-buffer
1089 * @inum: the inode number
1090 *
1091 * This function returns with %1 if the write-buffer contains some data from the
1092 * given inode otherwise it returns with %0.
1093 */
1094static int wbuf_has_ino(struct ubifs_wbuf *wbuf, ino_t inum)
1095{
1096        int i, ret = 0;
1097
1098        spin_lock(&wbuf->lock);
1099        for (i = 0; i < wbuf->next_ino; i++)
1100                if (inum == wbuf->inodes[i]) {
1101                        ret = 1;
1102                        break;
1103                }
1104        spin_unlock(&wbuf->lock);
1105
1106        return ret;
1107}
1108
1109/**
1110 * ubifs_sync_wbufs_by_inode - synchronize write-buffers for an inode.
1111 * @c: UBIFS file-system description object
1112 * @inode: inode to synchronize
1113 *
1114 * This function synchronizes write-buffers which contain nodes belonging to
1115 * @inode. Returns zero in case of success and a negative error code in case of
1116 * failure.
1117 */
1118int ubifs_sync_wbufs_by_inode(struct ubifs_info *c, struct inode *inode)
1119{
1120        int i, err = 0;
1121
1122        for (i = 0; i < c->jhead_cnt; i++) {
1123                struct ubifs_wbuf *wbuf = &c->jheads[i].wbuf;
1124
1125                if (i == GCHD)
1126                        /*
1127                         * GC head is special, do not look at it. Even if the
1128                         * head contains something related to this inode, it is
1129                         * a _copy_ of corresponding on-flash node which sits
1130                         * somewhere else.
1131                         */
1132                        continue;
1133
1134                if (!wbuf_has_ino(wbuf, inode->i_ino))
1135                        continue;
1136
1137                mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
1138                if (wbuf_has_ino(wbuf, inode->i_ino))
1139                        err = ubifs_wbuf_sync_nolock(wbuf);
1140                mutex_unlock(&wbuf->io_mutex);
1141
1142                if (err) {
1143                        ubifs_ro_mode(c, err);
1144                        return err;
1145                }
1146        }
1147        return 0;
1148}
1149
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