linux/fs/jbd2/revoke.c
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   1/*
   2 * linux/fs/jbd2/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 * We cache revoke status of a buffer in the current transaction in b_states
  51 * bits.  As the name says, revokevalid flag indicates that the cached revoke
  52 * status of a buffer is valid and we can rely on the cached status.
  53 *
  54 * Revoke information on buffers is a tri-state value:
  55 *
  56 * RevokeValid clear:   no cached revoke status, need to look it up
  57 * RevokeValid set, Revoked clear:
  58 *                      buffer has not been revoked, and cancel_revoke
  59 *                      need do nothing.
  60 * RevokeValid set, Revoked set:
  61 *                      buffer has been revoked.
  62 *
  63 * Locking rules:
  64 * We keep two hash tables of revoke records. One hashtable belongs to the
  65 * running transaction (is pointed to by journal->j_revoke), the other one
  66 * belongs to the committing transaction. Accesses to the second hash table
  67 * happen only from the kjournald and no other thread touches this table.  Also
  68 * journal_switch_revoke_table() which switches which hashtable belongs to the
  69 * running and which to the committing transaction is called only from
  70 * kjournald. Therefore we need no locks when accessing the hashtable belonging
  71 * to the committing transaction.
  72 *
  73 * All users operating on the hash table belonging to the running transaction
  74 * have a handle to the transaction. Therefore they are safe from kjournald
  75 * switching hash tables under them. For operations on the lists of entries in
  76 * the hash table j_revoke_lock is used.
  77 *
  78 * Finally, also replay code uses the hash tables but at this moment no one else
  79 * can touch them (filesystem isn't mounted yet) and hence no locking is
  80 * needed.
  81 */
  82
  83#ifndef __KERNEL__
  84#include "jfs_user.h"
  85#else
  86#include <linux/time.h>
  87#include <linux/fs.h>
  88#include <linux/jbd2.h>
  89#include <linux/errno.h>
  90#include <linux/slab.h>
  91#include <linux/list.h>
  92#include <linux/init.h>
  93#include <linux/bio.h>
  94#endif
  95#include <linux/log2.h>
  96
  97static struct kmem_cache *jbd2_revoke_record_cache;
  98static struct kmem_cache *jbd2_revoke_table_cache;
  99
 100/* Each revoke record represents one single revoked block.  During
 101   journal replay, this involves recording the transaction ID of the
 102   last transaction to revoke this block. */
 103
 104struct jbd2_revoke_record_s
 105{
 106        struct list_head  hash;
 107        tid_t             sequence;     /* Used for recovery only */
 108        unsigned long long        blocknr;
 109};
 110
 111
 112/* The revoke table is just a simple hash table of revoke records. */
 113struct jbd2_revoke_table_s
 114{
 115        /* It is conceivable that we might want a larger hash table
 116         * for recovery.  Must be a power of two. */
 117        int               hash_size;
 118        int               hash_shift;
 119        struct list_head *hash_table;
 120};
 121
 122
 123#ifdef __KERNEL__
 124static void write_one_revoke_record(journal_t *, transaction_t *,
 125                                    struct list_head *,
 126                                    struct buffer_head **, int *,
 127                                    struct jbd2_revoke_record_s *, int);
 128static void flush_descriptor(journal_t *, struct buffer_head *, int, int);
 129#endif
 130
 131/* Utility functions to maintain the revoke table */
 132
 133/* Borrowed from buffer.c: this is a tried and tested block hash function */
 134static inline int hash(journal_t *journal, unsigned long long block)
 135{
 136        struct jbd2_revoke_table_s *table = journal->j_revoke;
 137        int hash_shift = table->hash_shift;
 138        int hash = (int)block ^ (int)((block >> 31) >> 1);
 139
 140        return ((hash << (hash_shift - 6)) ^
 141                (hash >> 13) ^
 142                (hash << (hash_shift - 12))) & (table->hash_size - 1);
 143}
 144
 145static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
 146                              tid_t seq)
 147{
 148        struct list_head *hash_list;
 149        struct jbd2_revoke_record_s *record;
 150
 151repeat:
 152        record = kmem_cache_alloc(jbd2_revoke_record_cache, GFP_NOFS);
 153        if (!record)
 154                goto oom;
 155
 156        record->sequence = seq;
 157        record->blocknr = blocknr;
 158        hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
 159        spin_lock(&journal->j_revoke_lock);
 160        list_add(&record->hash, hash_list);
 161        spin_unlock(&journal->j_revoke_lock);
 162        return 0;
 163
 164oom:
 165        if (!journal_oom_retry)
 166                return -ENOMEM;
 167        jbd_debug(1, "ENOMEM in %s, retrying\n", __func__);
 168        yield();
 169        goto repeat;
 170}
 171
 172/* Find a revoke record in the journal's hash table. */
 173
 174static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
 175                                                      unsigned long long blocknr)
 176{
 177        struct list_head *hash_list;
 178        struct jbd2_revoke_record_s *record;
 179
 180        hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
 181
 182        spin_lock(&journal->j_revoke_lock);
 183        record = (struct jbd2_revoke_record_s *) hash_list->next;
 184        while (&(record->hash) != hash_list) {
 185                if (record->blocknr == blocknr) {
 186                        spin_unlock(&journal->j_revoke_lock);
 187                        return record;
 188                }
 189                record = (struct jbd2_revoke_record_s *) record->hash.next;
 190        }
 191        spin_unlock(&journal->j_revoke_lock);
 192        return NULL;
 193}
 194
 195void jbd2_journal_destroy_revoke_caches(void)
 196{
 197        if (jbd2_revoke_record_cache) {
 198                kmem_cache_destroy(jbd2_revoke_record_cache);
 199                jbd2_revoke_record_cache = NULL;
 200        }
 201        if (jbd2_revoke_table_cache) {
 202                kmem_cache_destroy(jbd2_revoke_table_cache);
 203                jbd2_revoke_table_cache = NULL;
 204        }
 205}
 206
 207int __init jbd2_journal_init_revoke_caches(void)
 208{
 209        J_ASSERT(!jbd2_revoke_record_cache);
 210        J_ASSERT(!jbd2_revoke_table_cache);
 211
 212        jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s,
 213                                        SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY);
 214        if (!jbd2_revoke_record_cache)
 215                goto record_cache_failure;
 216
 217        jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s,
 218                                             SLAB_TEMPORARY);
 219        if (!jbd2_revoke_table_cache)
 220                goto table_cache_failure;
 221        return 0;
 222table_cache_failure:
 223        jbd2_journal_destroy_revoke_caches();
 224record_cache_failure:
 225                return -ENOMEM;
 226}
 227
 228static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size)
 229{
 230        int shift = 0;
 231        int tmp = hash_size;
 232        struct jbd2_revoke_table_s *table;
 233
 234        table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
 235        if (!table)
 236                goto out;
 237
 238        while((tmp >>= 1UL) != 0UL)
 239                shift++;
 240
 241        table->hash_size = hash_size;
 242        table->hash_shift = shift;
 243        table->hash_table =
 244                kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
 245        if (!table->hash_table) {
 246                kmem_cache_free(jbd2_revoke_table_cache, table);
 247                table = NULL;
 248                goto out;
 249        }
 250
 251        for (tmp = 0; tmp < hash_size; tmp++)
 252                INIT_LIST_HEAD(&table->hash_table[tmp]);
 253
 254out:
 255        return table;
 256}
 257
 258static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table)
 259{
 260        int i;
 261        struct list_head *hash_list;
 262
 263        for (i = 0; i < table->hash_size; i++) {
 264                hash_list = &table->hash_table[i];
 265                J_ASSERT(list_empty(hash_list));
 266        }
 267
 268        kfree(table->hash_table);
 269        kmem_cache_free(jbd2_revoke_table_cache, table);
 270}
 271
 272/* Initialise the revoke table for a given journal to a given size. */
 273int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
 274{
 275        J_ASSERT(journal->j_revoke_table[0] == NULL);
 276        J_ASSERT(is_power_of_2(hash_size));
 277
 278        journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size);
 279        if (!journal->j_revoke_table[0])
 280                goto fail0;
 281
 282        journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size);
 283        if (!journal->j_revoke_table[1])
 284                goto fail1;
 285
 286        journal->j_revoke = journal->j_revoke_table[1];
 287
 288        spin_lock_init(&journal->j_revoke_lock);
 289
 290        return 0;
 291
 292fail1:
 293        jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
 294fail0:
 295        return -ENOMEM;
 296}
 297
 298/* Destroy a journal's revoke table.  The table must already be empty! */
 299void jbd2_journal_destroy_revoke(journal_t *journal)
 300{
 301        journal->j_revoke = NULL;
 302        if (journal->j_revoke_table[0])
 303                jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
 304        if (journal->j_revoke_table[1])
 305                jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]);
 306}
 307
 308
 309#ifdef __KERNEL__
 310
 311/*
 312 * jbd2_journal_revoke: revoke a given buffer_head from the journal.  This
 313 * prevents the block from being replayed during recovery if we take a
 314 * crash after this current transaction commits.  Any subsequent
 315 * metadata writes of the buffer in this transaction cancel the
 316 * revoke.
 317 *
 318 * Note that this call may block --- it is up to the caller to make
 319 * sure that there are no further calls to journal_write_metadata
 320 * before the revoke is complete.  In ext3, this implies calling the
 321 * revoke before clearing the block bitmap when we are deleting
 322 * metadata.
 323 *
 324 * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
 325 * parameter, but does _not_ forget the buffer_head if the bh was only
 326 * found implicitly.
 327 *
 328 * bh_in may not be a journalled buffer - it may have come off
 329 * the hash tables without an attached journal_head.
 330 *
 331 * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
 332 * by one.
 333 */
 334
 335int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
 336                   struct buffer_head *bh_in)
 337{
 338        struct buffer_head *bh = NULL;
 339        journal_t *journal;
 340        struct block_device *bdev;
 341        int err;
 342
 343        might_sleep();
 344        if (bh_in)
 345                BUFFER_TRACE(bh_in, "enter");
 346
 347        journal = handle->h_transaction->t_journal;
 348        if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
 349                J_ASSERT (!"Cannot set revoke feature!");
 350                return -EINVAL;
 351        }
 352
 353        bdev = journal->j_fs_dev;
 354        bh = bh_in;
 355
 356        if (!bh) {
 357                bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
 358                if (bh)
 359                        BUFFER_TRACE(bh, "found on hash");
 360        }
 361#ifdef JBD2_EXPENSIVE_CHECKING
 362        else {
 363                struct buffer_head *bh2;
 364
 365                /* If there is a different buffer_head lying around in
 366                 * memory anywhere... */
 367                bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
 368                if (bh2) {
 369                        /* ... and it has RevokeValid status... */
 370                        if (bh2 != bh && buffer_revokevalid(bh2))
 371                                /* ...then it better be revoked too,
 372                                 * since it's illegal to create a revoke
 373                                 * record against a buffer_head which is
 374                                 * not marked revoked --- that would
 375                                 * risk missing a subsequent revoke
 376                                 * cancel. */
 377                                J_ASSERT_BH(bh2, buffer_revoked(bh2));
 378                        put_bh(bh2);
 379                }
 380        }
 381#endif
 382
 383        /* We really ought not ever to revoke twice in a row without
 384           first having the revoke cancelled: it's illegal to free a
 385           block twice without allocating it in between! */
 386        if (bh) {
 387                if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
 388                                 "inconsistent data on disk")) {
 389                        if (!bh_in)
 390                                brelse(bh);
 391                        return -EIO;
 392                }
 393                set_buffer_revoked(bh);
 394                set_buffer_revokevalid(bh);
 395                if (bh_in) {
 396                        BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
 397                        jbd2_journal_forget(handle, bh_in);
 398                } else {
 399                        BUFFER_TRACE(bh, "call brelse");
 400                        __brelse(bh);
 401                }
 402        }
 403
 404        jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
 405        err = insert_revoke_hash(journal, blocknr,
 406                                handle->h_transaction->t_tid);
 407        BUFFER_TRACE(bh_in, "exit");
 408        return err;
 409}
 410
 411/*
 412 * Cancel an outstanding revoke.  For use only internally by the
 413 * journaling code (called from jbd2_journal_get_write_access).
 414 *
 415 * We trust buffer_revoked() on the buffer if the buffer is already
 416 * being journaled: if there is no revoke pending on the buffer, then we
 417 * don't do anything here.
 418 *
 419 * This would break if it were possible for a buffer to be revoked and
 420 * discarded, and then reallocated within the same transaction.  In such
 421 * a case we would have lost the revoked bit, but when we arrived here
 422 * the second time we would still have a pending revoke to cancel.  So,
 423 * do not trust the Revoked bit on buffers unless RevokeValid is also
 424 * set.
 425 */
 426int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
 427{
 428        struct jbd2_revoke_record_s *record;
 429        journal_t *journal = handle->h_transaction->t_journal;
 430        int need_cancel;
 431        int did_revoke = 0;     /* akpm: debug */
 432        struct buffer_head *bh = jh2bh(jh);
 433
 434        jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
 435
 436        /* Is the existing Revoke bit valid?  If so, we trust it, and
 437         * only perform the full cancel if the revoke bit is set.  If
 438         * not, we can't trust the revoke bit, and we need to do the
 439         * full search for a revoke record. */
 440        if (test_set_buffer_revokevalid(bh)) {
 441                need_cancel = test_clear_buffer_revoked(bh);
 442        } else {
 443                need_cancel = 1;
 444                clear_buffer_revoked(bh);
 445        }
 446
 447        if (need_cancel) {
 448                record = find_revoke_record(journal, bh->b_blocknr);
 449                if (record) {
 450                        jbd_debug(4, "cancelled existing revoke on "
 451                                  "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
 452                        spin_lock(&journal->j_revoke_lock);
 453                        list_del(&record->hash);
 454                        spin_unlock(&journal->j_revoke_lock);
 455                        kmem_cache_free(jbd2_revoke_record_cache, record);
 456                        did_revoke = 1;
 457                }
 458        }
 459
 460#ifdef JBD2_EXPENSIVE_CHECKING
 461        /* There better not be one left behind by now! */
 462        record = find_revoke_record(journal, bh->b_blocknr);
 463        J_ASSERT_JH(jh, record == NULL);
 464#endif
 465
 466        /* Finally, have we just cleared revoke on an unhashed
 467         * buffer_head?  If so, we'd better make sure we clear the
 468         * revoked status on any hashed alias too, otherwise the revoke
 469         * state machine will get very upset later on. */
 470        if (need_cancel) {
 471                struct buffer_head *bh2;
 472                bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
 473                if (bh2) {
 474                        if (bh2 != bh)
 475                                clear_buffer_revoked(bh2);
 476                        __brelse(bh2);
 477                }
 478        }
 479        return did_revoke;
 480}
 481
 482/*
 483 * journal_clear_revoked_flag clears revoked flag of buffers in
 484 * revoke table to reflect there is no revoked buffers in the next
 485 * transaction which is going to be started.
 486 */
 487void jbd2_clear_buffer_revoked_flags(journal_t *journal)
 488{
 489        struct jbd2_revoke_table_s *revoke = journal->j_revoke;
 490        int i = 0;
 491
 492        for (i = 0; i < revoke->hash_size; i++) {
 493                struct list_head *hash_list;
 494                struct list_head *list_entry;
 495                hash_list = &revoke->hash_table[i];
 496
 497                list_for_each(list_entry, hash_list) {
 498                        struct jbd2_revoke_record_s *record;
 499                        struct buffer_head *bh;
 500                        record = (struct jbd2_revoke_record_s *)list_entry;
 501                        bh = __find_get_block(journal->j_fs_dev,
 502                                              record->blocknr,
 503                                              journal->j_blocksize);
 504                        if (bh) {
 505                                clear_buffer_revoked(bh);
 506                                __brelse(bh);
 507                        }
 508                }
 509        }
 510}
 511
 512/* journal_switch_revoke table select j_revoke for next transaction
 513 * we do not want to suspend any processing until all revokes are
 514 * written -bzzz
 515 */
 516void jbd2_journal_switch_revoke_table(journal_t *journal)
 517{
 518        int i;
 519
 520        if (journal->j_revoke == journal->j_revoke_table[0])
 521                journal->j_revoke = journal->j_revoke_table[1];
 522        else
 523                journal->j_revoke = journal->j_revoke_table[0];
 524
 525        for (i = 0; i < journal->j_revoke->hash_size; i++)
 526                INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
 527}
 528
 529/*
 530 * Write revoke records to the journal for all entries in the current
 531 * revoke hash, deleting the entries as we go.
 532 */
 533void jbd2_journal_write_revoke_records(journal_t *journal,
 534                                       transaction_t *transaction,
 535                                       struct list_head *log_bufs,
 536                                       int write_op)
 537{
 538        struct buffer_head *descriptor;
 539        struct jbd2_revoke_record_s *record;
 540        struct jbd2_revoke_table_s *revoke;
 541        struct list_head *hash_list;
 542        int i, offset, count;
 543
 544        descriptor = NULL;
 545        offset = 0;
 546        count = 0;
 547
 548        /* select revoke table for committing transaction */
 549        revoke = journal->j_revoke == journal->j_revoke_table[0] ?
 550                journal->j_revoke_table[1] : journal->j_revoke_table[0];
 551
 552        for (i = 0; i < revoke->hash_size; i++) {
 553                hash_list = &revoke->hash_table[i];
 554
 555                while (!list_empty(hash_list)) {
 556                        record = (struct jbd2_revoke_record_s *)
 557                                hash_list->next;
 558                        write_one_revoke_record(journal, transaction, log_bufs,
 559                                                &descriptor, &offset,
 560                                                record, write_op);
 561                        count++;
 562                        list_del(&record->hash);
 563                        kmem_cache_free(jbd2_revoke_record_cache, record);
 564                }
 565        }
 566        if (descriptor)
 567                flush_descriptor(journal, descriptor, offset, write_op);
 568        jbd_debug(1, "Wrote %d revoke records\n", count);
 569}
 570
 571/*
 572 * Write out one revoke record.  We need to create a new descriptor
 573 * block if the old one is full or if we have not already created one.
 574 */
 575
 576static void write_one_revoke_record(journal_t *journal,
 577                                    transaction_t *transaction,
 578                                    struct list_head *log_bufs,
 579                                    struct buffer_head **descriptorp,
 580                                    int *offsetp,
 581                                    struct jbd2_revoke_record_s *record,
 582                                    int write_op)
 583{
 584        int csum_size = 0;
 585        struct buffer_head *descriptor;
 586        int offset;
 587        journal_header_t *header;
 588
 589        /* If we are already aborting, this all becomes a noop.  We
 590           still need to go round the loop in
 591           jbd2_journal_write_revoke_records in order to free all of the
 592           revoke records: only the IO to the journal is omitted. */
 593        if (is_journal_aborted(journal))
 594                return;
 595
 596        descriptor = *descriptorp;
 597        offset = *offsetp;
 598
 599        /* Do we need to leave space at the end for a checksum? */
 600        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 601                csum_size = sizeof(struct jbd2_journal_revoke_tail);
 602
 603        /* Make sure we have a descriptor with space left for the record */
 604        if (descriptor) {
 605                if (offset >= journal->j_blocksize - csum_size) {
 606                        flush_descriptor(journal, descriptor, offset, write_op);
 607                        descriptor = NULL;
 608                }
 609        }
 610
 611        if (!descriptor) {
 612                descriptor = jbd2_journal_get_descriptor_buffer(journal);
 613                if (!descriptor)
 614                        return;
 615                header = (journal_header_t *)descriptor->b_data;
 616                header->h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
 617                header->h_blocktype = cpu_to_be32(JBD2_REVOKE_BLOCK);
 618                header->h_sequence  = cpu_to_be32(transaction->t_tid);
 619
 620                /* Record it so that we can wait for IO completion later */
 621                BUFFER_TRACE(descriptor, "file in log_bufs");
 622                jbd2_file_log_bh(log_bufs, descriptor);
 623
 624                offset = sizeof(jbd2_journal_revoke_header_t);
 625                *descriptorp = descriptor;
 626        }
 627
 628        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) {
 629                * ((__be64 *)(&descriptor->b_data[offset])) =
 630                        cpu_to_be64(record->blocknr);
 631                offset += 8;
 632
 633        } else {
 634                * ((__be32 *)(&descriptor->b_data[offset])) =
 635                        cpu_to_be32(record->blocknr);
 636                offset += 4;
 637        }
 638
 639        *offsetp = offset;
 640}
 641
 642static void jbd2_revoke_csum_set(journal_t *j, struct buffer_head *bh)
 643{
 644        struct jbd2_journal_revoke_tail *tail;
 645        __u32 csum;
 646
 647        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 648                return;
 649
 650        tail = (struct jbd2_journal_revoke_tail *)(bh->b_data + j->j_blocksize -
 651                        sizeof(struct jbd2_journal_revoke_tail));
 652        tail->r_checksum = 0;
 653        csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize);
 654        tail->r_checksum = cpu_to_be32(csum);
 655}
 656
 657/*
 658 * Flush a revoke descriptor out to the journal.  If we are aborting,
 659 * this is a noop; otherwise we are generating a buffer which needs to
 660 * be waited for during commit, so it has to go onto the appropriate
 661 * journal buffer list.
 662 */
 663
 664static void flush_descriptor(journal_t *journal,
 665                             struct buffer_head *descriptor,
 666                             int offset, int write_op)
 667{
 668        jbd2_journal_revoke_header_t *header;
 669
 670        if (is_journal_aborted(journal)) {
 671                put_bh(descriptor);
 672                return;
 673        }
 674
 675        header = (jbd2_journal_revoke_header_t *)descriptor->b_data;
 676        header->r_count = cpu_to_be32(offset);
 677        jbd2_revoke_csum_set(journal, descriptor);
 678
 679        set_buffer_jwrite(descriptor);
 680        BUFFER_TRACE(descriptor, "write");
 681        set_buffer_dirty(descriptor);
 682        write_dirty_buffer(descriptor, write_op);
 683}
 684#endif
 685
 686/*
 687 * Revoke support for recovery.
 688 *
 689 * Recovery needs to be able to:
 690 *
 691 *  record all revoke records, including the tid of the latest instance
 692 *  of each revoke in the journal
 693 *
 694 *  check whether a given block in a given transaction should be replayed
 695 *  (ie. has not been revoked by a revoke record in that or a subsequent
 696 *  transaction)
 697 *
 698 *  empty the revoke table after recovery.
 699 */
 700
 701/*
 702 * First, setting revoke records.  We create a new revoke record for
 703 * every block ever revoked in the log as we scan it for recovery, and
 704 * we update the existing records if we find multiple revokes for a
 705 * single block.
 706 */
 707
 708int jbd2_journal_set_revoke(journal_t *journal,
 709                       unsigned long long blocknr,
 710                       tid_t sequence)
 711{
 712        struct jbd2_revoke_record_s *record;
 713
 714        record = find_revoke_record(journal, blocknr);
 715        if (record) {
 716                /* If we have multiple occurrences, only record the
 717                 * latest sequence number in the hashed record */
 718                if (tid_gt(sequence, record->sequence))
 719                        record->sequence = sequence;
 720                return 0;
 721        }
 722        return insert_revoke_hash(journal, blocknr, sequence);
 723}
 724
 725/*
 726 * Test revoke records.  For a given block referenced in the log, has
 727 * that block been revoked?  A revoke record with a given transaction
 728 * sequence number revokes all blocks in that transaction and earlier
 729 * ones, but later transactions still need replayed.
 730 */
 731
 732int jbd2_journal_test_revoke(journal_t *journal,
 733                        unsigned long long blocknr,
 734                        tid_t sequence)
 735{
 736        struct jbd2_revoke_record_s *record;
 737
 738        record = find_revoke_record(journal, blocknr);
 739        if (!record)
 740                return 0;
 741        if (tid_gt(sequence, record->sequence))
 742                return 0;
 743        return 1;
 744}
 745
 746/*
 747 * Finally, once recovery is over, we need to clear the revoke table so
 748 * that it can be reused by the running filesystem.
 749 */
 750
 751void jbd2_journal_clear_revoke(journal_t *journal)
 752{
 753        int i;
 754        struct list_head *hash_list;
 755        struct jbd2_revoke_record_s *record;
 756        struct jbd2_revoke_table_s *revoke;
 757
 758        revoke = journal->j_revoke;
 759
 760        for (i = 0; i < revoke->hash_size; i++) {
 761                hash_list = &revoke->hash_table[i];
 762                while (!list_empty(hash_list)) {
 763                        record = (struct jbd2_revoke_record_s*) hash_list->next;
 764                        list_del(&record->hash);
 765                        kmem_cache_free(jbd2_revoke_record_cache, record);
 766                }
 767        }
 768}
 769
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