linux/fs/jbd/revoke.c
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   1/*
   2 * linux/fs/jbd/revoke.c
   3 *
   4 * Written by Stephen C. Tweedie <sct@redhat.com>, 2000
   5 *
   6 * Copyright 2000 Red Hat corp --- All Rights Reserved
   7 *
   8 * This file is part of the Linux kernel and is made available under
   9 * the terms of the GNU General Public License, version 2, or at your
  10 * option, any later version, incorporated herein by reference.
  11 *
  12 * Journal revoke routines for the generic filesystem journaling code;
  13 * part of the ext2fs journaling system.
  14 *
  15 * Revoke is the mechanism used to prevent old log records for deleted
  16 * metadata from being replayed on top of newer data using the same
  17 * blocks.  The revoke mechanism is used in two separate places:
  18 *
  19 * + Commit: during commit we write the entire list of the current
  20 *   transaction's revoked blocks to the journal
  21 *
  22 * + Recovery: during recovery we record the transaction ID of all
  23 *   revoked blocks.  If there are multiple revoke records in the log
  24 *   for a single block, only the last one counts, and if there is a log
  25 *   entry for a block beyond the last revoke, then that log entry still
  26 *   gets replayed.
  27 *
  28 * We can get interactions between revokes and new log data within a
  29 * single transaction:
  30 *
  31 * Block is revoked and then journaled:
  32 *   The desired end result is the journaling of the new block, so we
  33 *   cancel the revoke before the transaction commits.
  34 *
  35 * Block is journaled and then revoked:
  36 *   The revoke must take precedence over the write of the block, so we
  37 *   need either to cancel the journal entry or to write the revoke
  38 *   later in the log than the log block.  In this case, we choose the
  39 *   latter: journaling a block cancels any revoke record for that block
  40 *   in the current transaction, so any revoke for that block in the
  41 *   transaction must have happened after the block was journaled and so
  42 *   the revoke must take precedence.
  43 *
  44 * Block is revoked and then written as data:
  45 *   The data write is allowed to succeed, but the revoke is _not_
  46 *   cancelled.  We still need to prevent old log records from
  47 *   overwriting the new data.  We don't even need to clear the revoke
  48 *   bit here.
  49 *
  50 * Revoke information on buffers is a tri-state value:
  51 *
  52 * RevokeValid clear:   no cached revoke status, need to look it up
  53 * RevokeValid set, Revoked clear:
  54 *                      buffer has not been revoked, and cancel_revoke
  55 *                      need do nothing.
  56 * RevokeValid set, Revoked set:
  57 *                      buffer has been revoked.
  58 */
  59
  60#ifndef __KERNEL__
  61#include "jfs_user.h"
  62#else
  63#include <linux/time.h>
  64#include <linux/fs.h>
  65#include <linux/jbd.h>
  66#include <linux/errno.h>
  67#include <linux/slab.h>
  68#include <linux/list.h>
  69#include <linux/init.h>
  70#endif
  71#include <linux/log2.h>
  72
  73static struct kmem_cache *revoke_record_cache;
  74static struct kmem_cache *revoke_table_cache;
  75
  76/* Each revoke record represents one single revoked block.  During
  77   journal replay, this involves recording the transaction ID of the
  78   last transaction to revoke this block. */
  79
  80struct jbd_revoke_record_s
  81{
  82        struct list_head  hash;
  83        tid_t             sequence;     /* Used for recovery only */
  84        unsigned long     blocknr;
  85};
  86
  87
  88/* The revoke table is just a simple hash table of revoke records. */
  89struct jbd_revoke_table_s
  90{
  91        /* It is conceivable that we might want a larger hash table
  92         * for recovery.  Must be a power of two. */
  93        int               hash_size;
  94        int               hash_shift;
  95        struct list_head *hash_table;
  96};
  97
  98
  99#ifdef __KERNEL__
 100static void write_one_revoke_record(journal_t *, transaction_t *,
 101                                    struct journal_head **, int *,
 102                                    struct jbd_revoke_record_s *);
 103static void flush_descriptor(journal_t *, struct journal_head *, int);
 104#endif
 105
 106/* Utility functions to maintain the revoke table */
 107
 108/* Borrowed from buffer.c: this is a tried and tested block hash function */
 109static inline int hash(journal_t *journal, unsigned long block)
 110{
 111        struct jbd_revoke_table_s *table = journal->j_revoke;
 112        int hash_shift = table->hash_shift;
 113
 114        return ((block << (hash_shift - 6)) ^
 115                (block >> 13) ^
 116                (block << (hash_shift - 12))) & (table->hash_size - 1);
 117}
 118
 119static int insert_revoke_hash(journal_t *journal, unsigned long blocknr,
 120                              tid_t seq)
 121{
 122        struct list_head *hash_list;
 123        struct jbd_revoke_record_s *record;
 124
 125repeat:
 126        record = kmem_cache_alloc(revoke_record_cache, GFP_NOFS);
 127        if (!record)
 128                goto oom;
 129
 130        record->sequence = seq;
 131        record->blocknr = blocknr;
 132        hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
 133        spin_lock(&journal->j_revoke_lock);
 134        list_add(&record->hash, hash_list);
 135        spin_unlock(&journal->j_revoke_lock);
 136        return 0;
 137
 138oom:
 139        if (!journal_oom_retry)
 140                return -ENOMEM;
 141        jbd_debug(1, "ENOMEM in %s, retrying\n", __FUNCTION__);
 142        yield();
 143        goto repeat;
 144}
 145
 146/* Find a revoke record in the journal's hash table. */
 147
 148static struct jbd_revoke_record_s *find_revoke_record(journal_t *journal,
 149                                                      unsigned long blocknr)
 150{
 151        struct list_head *hash_list;
 152        struct jbd_revoke_record_s *record;
 153
 154        hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
 155
 156        spin_lock(&journal->j_revoke_lock);
 157        record = (struct jbd_revoke_record_s *) hash_list->next;
 158        while (&(record->hash) != hash_list) {
 159                if (record->blocknr == blocknr) {
 160                        spin_unlock(&journal->j_revoke_lock);
 161                        return record;
 162                }
 163                record = (struct jbd_revoke_record_s *) record->hash.next;
 164        }
 165        spin_unlock(&journal->j_revoke_lock);
 166        return NULL;
 167}
 168
 169int __init journal_init_revoke_caches(void)
 170{
 171        revoke_record_cache = kmem_cache_create("revoke_record",
 172                                           sizeof(struct jbd_revoke_record_s),
 173                                           0,
 174                                           SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY,
 175                                           NULL);
 176        if (revoke_record_cache == 0)
 177                return -ENOMEM;
 178
 179        revoke_table_cache = kmem_cache_create("revoke_table",
 180                                           sizeof(struct jbd_revoke_table_s),
 181                                           0, SLAB_TEMPORARY, NULL);
 182        if (revoke_table_cache == 0) {
 183                kmem_cache_destroy(revoke_record_cache);
 184                revoke_record_cache = NULL;
 185                return -ENOMEM;
 186        }
 187        return 0;
 188}
 189
 190void journal_destroy_revoke_caches(void)
 191{
 192        kmem_cache_destroy(revoke_record_cache);
 193        revoke_record_cache = NULL;
 194        kmem_cache_destroy(revoke_table_cache);
 195        revoke_table_cache = NULL;
 196}
 197
 198/* Initialise the revoke table for a given journal to a given size. */
 199
 200int journal_init_revoke(journal_t *journal, int hash_size)
 201{
 202        int shift, tmp;
 203
 204        J_ASSERT (journal->j_revoke_table[0] == NULL);
 205
 206        shift = 0;
 207        tmp = hash_size;
 208        while((tmp >>= 1UL) != 0UL)
 209                shift++;
 210
 211        journal->j_revoke_table[0] = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL);
 212        if (!journal->j_revoke_table[0])
 213                return -ENOMEM;
 214        journal->j_revoke = journal->j_revoke_table[0];
 215
 216        /* Check that the hash_size is a power of two */
 217        J_ASSERT(is_power_of_2(hash_size));
 218
 219        journal->j_revoke->hash_size = hash_size;
 220
 221        journal->j_revoke->hash_shift = shift;
 222
 223        journal->j_revoke->hash_table =
 224                kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
 225        if (!journal->j_revoke->hash_table) {
 226                kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]);
 227                journal->j_revoke = NULL;
 228                return -ENOMEM;
 229        }
 230
 231        for (tmp = 0; tmp < hash_size; tmp++)
 232                INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]);
 233
 234        journal->j_revoke_table[1] = kmem_cache_alloc(revoke_table_cache, GFP_KERNEL);
 235        if (!journal->j_revoke_table[1]) {
 236                kfree(journal->j_revoke_table[0]->hash_table);
 237                kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]);
 238                return -ENOMEM;
 239        }
 240
 241        journal->j_revoke = journal->j_revoke_table[1];
 242
 243        /* Check that the hash_size is a power of two */
 244        J_ASSERT(is_power_of_2(hash_size));
 245
 246        journal->j_revoke->hash_size = hash_size;
 247
 248        journal->j_revoke->hash_shift = shift;
 249
 250        journal->j_revoke->hash_table =
 251                kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
 252        if (!journal->j_revoke->hash_table) {
 253                kfree(journal->j_revoke_table[0]->hash_table);
 254                kmem_cache_free(revoke_table_cache, journal->j_revoke_table[0]);
 255                kmem_cache_free(revoke_table_cache, journal->j_revoke_table[1]);
 256                journal->j_revoke = NULL;
 257                return -ENOMEM;
 258        }
 259
 260        for (tmp = 0; tmp < hash_size; tmp++)
 261                INIT_LIST_HEAD(&journal->j_revoke->hash_table[tmp]);
 262
 263        spin_lock_init(&journal->j_revoke_lock);
 264
 265        return 0;
 266}
 267
 268/* Destoy a journal's revoke table.  The table must already be empty! */
 269
 270void journal_destroy_revoke(journal_t *journal)
 271{
 272        struct jbd_revoke_table_s *table;
 273        struct list_head *hash_list;
 274        int i;
 275
 276        table = journal->j_revoke_table[0];
 277        if (!table)
 278                return;
 279
 280        for (i=0; i<table->hash_size; i++) {
 281                hash_list = &table->hash_table[i];
 282                J_ASSERT (list_empty(hash_list));
 283        }
 284
 285        kfree(table->hash_table);
 286        kmem_cache_free(revoke_table_cache, table);
 287        journal->j_revoke = NULL;
 288
 289        table = journal->j_revoke_table[1];
 290        if (!table)
 291                return;
 292
 293        for (i=0; i<table->hash_size; i++) {
 294                hash_list = &table->hash_table[i];
 295                J_ASSERT (list_empty(hash_list));
 296        }
 297
 298        kfree(table->hash_table);
 299        kmem_cache_free(revoke_table_cache, table);
 300        journal->j_revoke = NULL;
 301}
 302
 303
 304#ifdef __KERNEL__
 305
 306/*
 307 * journal_revoke: revoke a given buffer_head from the journal.  This
 308 * prevents the block from being replayed during recovery if we take a
 309 * crash after this current transaction commits.  Any subsequent
 310 * metadata writes of the buffer in this transaction cancel the
 311 * revoke.
 312 *
 313 * Note that this call may block --- it is up to the caller to make
 314 * sure that there are no further calls to journal_write_metadata
 315 * before the revoke is complete.  In ext3, this implies calling the
 316 * revoke before clearing the block bitmap when we are deleting
 317 * metadata.
 318 *
 319 * Revoke performs a journal_forget on any buffer_head passed in as a
 320 * parameter, but does _not_ forget the buffer_head if the bh was only
 321 * found implicitly.
 322 *
 323 * bh_in may not be a journalled buffer - it may have come off
 324 * the hash tables without an attached journal_head.
 325 *
 326 * If bh_in is non-zero, journal_revoke() will decrement its b_count
 327 * by one.
 328 */
 329
 330int journal_revoke(handle_t *handle, unsigned long blocknr,
 331                   struct buffer_head *bh_in)
 332{
 333        struct buffer_head *bh = NULL;
 334        journal_t *journal;
 335        struct block_device *bdev;
 336        int err;
 337
 338        might_sleep();
 339        if (bh_in)
 340                BUFFER_TRACE(bh_in, "enter");
 341
 342        journal = handle->h_transaction->t_journal;
 343        if (!journal_set_features(journal, 0, 0, JFS_FEATURE_INCOMPAT_REVOKE)){
 344                J_ASSERT (!"Cannot set revoke feature!");
 345                return -EINVAL;
 346        }
 347
 348        bdev = journal->j_fs_dev;
 349        bh = bh_in;
 350
 351        if (!bh) {
 352                bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
 353                if (bh)
 354                        BUFFER_TRACE(bh, "found on hash");
 355        }
 356#ifdef JBD_EXPENSIVE_CHECKING
 357        else {
 358                struct buffer_head *bh2;
 359
 360                /* If there is a different buffer_head lying around in
 361                 * memory anywhere... */
 362                bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
 363                if (bh2) {
 364                        /* ... and it has RevokeValid status... */
 365                        if (bh2 != bh && buffer_revokevalid(bh2))
 366                                /* ...then it better be revoked too,
 367                                 * since it's illegal to create a revoke
 368                                 * record against a buffer_head which is
 369                                 * not marked revoked --- that would
 370                                 * risk missing a subsequent revoke
 371                                 * cancel. */
 372                                J_ASSERT_BH(bh2, buffer_revoked(bh2));
 373                        put_bh(bh2);
 374                }
 375        }
 376#endif
 377
 378        /* We really ought not ever to revoke twice in a row without
 379           first having the revoke cancelled: it's illegal to free a
 380           block twice without allocating it in between! */
 381        if (bh) {
 382                if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
 383                                 "inconsistent data on disk")) {
 384                        if (!bh_in)
 385                                brelse(bh);
 386                        return -EIO;
 387                }
 388                set_buffer_revoked(bh);
 389                set_buffer_revokevalid(bh);
 390                if (bh_in) {
 391                        BUFFER_TRACE(bh_in, "call journal_forget");
 392                        journal_forget(handle, bh_in);
 393                } else {
 394                        BUFFER_TRACE(bh, "call brelse");
 395                        __brelse(bh);
 396                }
 397        }
 398
 399        jbd_debug(2, "insert revoke for block %lu, bh_in=%p\n", blocknr, bh_in);
 400        err = insert_revoke_hash(journal, blocknr,
 401                                handle->h_transaction->t_tid);
 402        BUFFER_TRACE(bh_in, "exit");
 403        return err;
 404}
 405
 406/*
 407 * Cancel an outstanding revoke.  For use only internally by the
 408 * journaling code (called from journal_get_write_access).
 409 *
 410 * We trust buffer_revoked() on the buffer if the buffer is already
 411 * being journaled: if there is no revoke pending on the buffer, then we
 412 * don't do anything here.
 413 *
 414 * This would break if it were possible for a buffer to be revoked and
 415 * discarded, and then reallocated within the same transaction.  In such
 416 * a case we would have lost the revoked bit, but when we arrived here
 417 * the second time we would still have a pending revoke to cancel.  So,
 418 * do not trust the Revoked bit on buffers unless RevokeValid is also
 419 * set.
 420 *
 421 * The caller must have the journal locked.
 422 */
 423int journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
 424{
 425        struct jbd_revoke_record_s *record;
 426        journal_t *journal = handle->h_transaction->t_journal;
 427        int need_cancel;
 428        int did_revoke = 0;     /* akpm: debug */
 429        struct buffer_head *bh = jh2bh(jh);
 430
 431        jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
 432
 433        /* Is the existing Revoke bit valid?  If so, we trust it, and
 434         * only perform the full cancel if the revoke bit is set.  If
 435         * not, we can't trust the revoke bit, and we need to do the
 436         * full search for a revoke record. */
 437        if (test_set_buffer_revokevalid(bh)) {
 438                need_cancel = test_clear_buffer_revoked(bh);
 439        } else {
 440                need_cancel = 1;
 441                clear_buffer_revoked(bh);
 442        }
 443
 444        if (need_cancel) {
 445                record = find_revoke_record(journal, bh->b_blocknr);
 446                if (record) {
 447                        jbd_debug(4, "cancelled existing revoke on "
 448                                  "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
 449                        spin_lock(&journal->j_revoke_lock);
 450                        list_del(&record->hash);
 451                        spin_unlock(&journal->j_revoke_lock);
 452                        kmem_cache_free(revoke_record_cache, record);
 453                        did_revoke = 1;
 454                }
 455        }
 456
 457#ifdef JBD_EXPENSIVE_CHECKING
 458        /* There better not be one left behind by now! */
 459        record = find_revoke_record(journal, bh->b_blocknr);
 460        J_ASSERT_JH(jh, record == NULL);
 461#endif
 462
 463        /* Finally, have we just cleared revoke on an unhashed
 464         * buffer_head?  If so, we'd better make sure we clear the
 465         * revoked status on any hashed alias too, otherwise the revoke
 466         * state machine will get very upset later on. */
 467        if (need_cancel) {
 468                struct buffer_head *bh2;
 469                bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
 470                if (bh2) {
 471                        if (bh2 != bh)
 472                                clear_buffer_revoked(bh2);
 473                        __brelse(bh2);
 474                }
 475        }
 476        return did_revoke;
 477}
 478
 479/* journal_switch_revoke table select j_revoke for next transaction
 480 * we do not want to suspend any processing until all revokes are
 481 * written -bzzz
 482 */
 483void journal_switch_revoke_table(journal_t *journal)
 484{
 485        int i;
 486
 487        if (journal->j_revoke == journal->j_revoke_table[0])
 488                journal->j_revoke = journal->j_revoke_table[1];
 489        else
 490                journal->j_revoke = journal->j_revoke_table[0];
 491
 492        for (i = 0; i < journal->j_revoke->hash_size; i++)
 493                INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
 494}
 495
 496/*
 497 * Write revoke records to the journal for all entries in the current
 498 * revoke hash, deleting the entries as we go.
 499 *
 500 * Called with the journal lock held.
 501 */
 502
 503void journal_write_revoke_records(journal_t *journal,
 504                                  transaction_t *transaction)
 505{
 506        struct journal_head *descriptor;
 507        struct jbd_revoke_record_s *record;
 508        struct jbd_revoke_table_s *revoke;
 509        struct list_head *hash_list;
 510        int i, offset, count;
 511
 512        descriptor = NULL;
 513        offset = 0;
 514        count = 0;
 515
 516        /* select revoke table for committing transaction */
 517        revoke = journal->j_revoke == journal->j_revoke_table[0] ?
 518                journal->j_revoke_table[1] : journal->j_revoke_table[0];
 519
 520        for (i = 0; i < revoke->hash_size; i++) {
 521                hash_list = &revoke->hash_table[i];
 522
 523                while (!list_empty(hash_list)) {
 524                        record = (struct jbd_revoke_record_s *)
 525                                hash_list->next;
 526                        write_one_revoke_record(journal, transaction,
 527                                                &descriptor, &offset,
 528                                                record);
 529                        count++;
 530                        list_del(&record->hash);
 531                        kmem_cache_free(revoke_record_cache, record);
 532                }
 533        }
 534        if (descriptor)
 535                flush_descriptor(journal, descriptor, offset);
 536        jbd_debug(1, "Wrote %d revoke records\n", count);
 537}
 538
 539/*
 540 * Write out one revoke record.  We need to create a new descriptor
 541 * block if the old one is full or if we have not already created one.
 542 */
 543
 544static void write_one_revoke_record(journal_t *journal,
 545                                    transaction_t *transaction,
 546                                    struct journal_head **descriptorp,
 547                                    int *offsetp,
 548                                    struct jbd_revoke_record_s *record)
 549{
 550        struct journal_head *descriptor;
 551        int offset;
 552        journal_header_t *header;
 553
 554        /* If we are already aborting, this all becomes a noop.  We
 555           still need to go round the loop in
 556           journal_write_revoke_records in order to free all of the
 557           revoke records: only the IO to the journal is omitted. */
 558        if (is_journal_aborted(journal))
 559                return;
 560
 561        descriptor = *descriptorp;
 562        offset = *offsetp;
 563
 564        /* Make sure we have a descriptor with space left for the record */
 565        if (descriptor) {
 566                if (offset == journal->j_blocksize) {
 567                        flush_descriptor(journal, descriptor, offset);
 568                        descriptor = NULL;
 569                }
 570        }
 571
 572        if (!descriptor) {
 573                descriptor = journal_get_descriptor_buffer(journal);
 574                if (!descriptor)
 575                        return;
 576                header = (journal_header_t *) &jh2bh(descriptor)->b_data[0];
 577                header->h_magic     = cpu_to_be32(JFS_MAGIC_NUMBER);
 578                header->h_blocktype = cpu_to_be32(JFS_REVOKE_BLOCK);
 579                header->h_sequence  = cpu_to_be32(transaction->t_tid);
 580
 581                /* Record it so that we can wait for IO completion later */
 582                JBUFFER_TRACE(descriptor, "file as BJ_LogCtl");
 583                journal_file_buffer(descriptor, transaction, BJ_LogCtl);
 584
 585                offset = sizeof(journal_revoke_header_t);
 586                *descriptorp = descriptor;
 587        }
 588
 589        * ((__be32 *)(&jh2bh(descriptor)->b_data[offset])) =
 590                cpu_to_be32(record->blocknr);
 591        offset += 4;
 592        *offsetp = offset;
 593}
 594
 595/*
 596 * Flush a revoke descriptor out to the journal.  If we are aborting,
 597 * this is a noop; otherwise we are generating a buffer which needs to
 598 * be waited for during commit, so it has to go onto the appropriate
 599 * journal buffer list.
 600 */
 601
 602static void flush_descriptor(journal_t *journal,
 603                             struct journal_head *descriptor,
 604                             int offset)
 605{
 606        journal_revoke_header_t *header;
 607        struct buffer_head *bh = jh2bh(descriptor);
 608
 609        if (is_journal_aborted(journal)) {
 610                put_bh(bh);
 611                return;
 612        }
 613
 614        header = (journal_revoke_header_t *) jh2bh(descriptor)->b_data;
 615        header->r_count = cpu_to_be32(offset);
 616        set_buffer_jwrite(bh);
 617        BUFFER_TRACE(bh, "write");
 618        set_buffer_dirty(bh);
 619        ll_rw_block(SWRITE, 1, &bh);
 620}
 621#endif
 622
 623/*
 624 * Revoke support for recovery.
 625 *
 626 * Recovery needs to be able to:
 627 *
 628 *  record all revoke records, including the tid of the latest instance
 629 *  of each revoke in the journal
 630 *
 631 *  check whether a given block in a given transaction should be replayed
 632 *  (ie. has not been revoked by a revoke record in that or a subsequent
 633 *  transaction)
 634 *
 635 *  empty the revoke table after recovery.
 636 */
 637
 638/*
 639 * First, setting revoke records.  We create a new revoke record for
 640 * every block ever revoked in the log as we scan it for recovery, and
 641 * we update the existing records if we find multiple revokes for a
 642 * single block.
 643 */
 644
 645int journal_set_revoke(journal_t *journal,
 646                       unsigned long blocknr,
 647                       tid_t sequence)
 648{
 649        struct jbd_revoke_record_s *record;
 650
 651        record = find_revoke_record(journal, blocknr);
 652        if (record) {
 653                /* If we have multiple occurrences, only record the
 654                 * latest sequence number in the hashed record */
 655                if (tid_gt(sequence, record->sequence))
 656                        record->sequence = sequence;
 657                return 0;
 658        }
 659        return insert_revoke_hash(journal, blocknr, sequence);
 660}
 661
 662/*
 663 * Test revoke records.  For a given block referenced in the log, has
 664 * that block been revoked?  A revoke record with a given transaction
 665 * sequence number revokes all blocks in that transaction and earlier
 666 * ones, but later transactions still need replayed.
 667 */
 668
 669int journal_test_revoke(journal_t *journal,
 670                        unsigned long blocknr,
 671                        tid_t sequence)
 672{
 673        struct jbd_revoke_record_s *record;
 674
 675        record = find_revoke_record(journal, blocknr);
 676        if (!record)
 677                return 0;
 678        if (tid_gt(sequence, record->sequence))
 679                return 0;
 680        return 1;
 681}
 682
 683/*
 684 * Finally, once recovery is over, we need to clear the revoke table so
 685 * that it can be reused by the running filesystem.
 686 */
 687
 688void journal_clear_revoke(journal_t *journal)
 689{
 690        int i;
 691        struct list_head *hash_list;
 692        struct jbd_revoke_record_s *record;
 693        struct jbd_revoke_table_s *revoke;
 694
 695        revoke = journal->j_revoke;
 696
 697        for (i = 0; i < revoke->hash_size; i++) {
 698                hash_list = &revoke->hash_table[i];
 699                while (!list_empty(hash_list)) {
 700                        record = (struct jbd_revoke_record_s*) hash_list->next;
 701                        list_del(&record->hash);
 702                        kmem_cache_free(revoke_record_cache, record);
 703                }
 704        }
 705}
 706