linux/fs/jbd2/revoke.c
<<
>>
Prefs
   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 journal_head **, int *,
 126                                    struct jbd2_revoke_record_s *, int);
 127static void flush_descriptor(journal_t *, struct journal_head *, int, int);
 128#endif
 129
 130/* Utility functions to maintain the revoke table */
 131
 132/* Borrowed from buffer.c: this is a tried and tested block hash function */
 133static inline int hash(journal_t *journal, unsigned long long block)
 134{
 135        struct jbd2_revoke_table_s *table = journal->j_revoke;
 136        int hash_shift = table->hash_shift;
 137        int hash = (int)block ^ (int)((block >> 31) >> 1);
 138
 139        return ((hash << (hash_shift - 6)) ^
 140                (hash >> 13) ^
 141                (hash << (hash_shift - 12))) & (table->hash_size - 1);
 142}
 143
 144static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
 145                              tid_t seq)
 146{
 147        struct list_head *hash_list;
 148        struct jbd2_revoke_record_s *record;
 149
 150repeat:
 151        record = kmem_cache_alloc(jbd2_revoke_record_cache, GFP_NOFS);
 152        if (!record)
 153                goto oom;
 154
 155        record->sequence = seq;
 156        record->blocknr = blocknr;
 157        hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
 158        spin_lock(&journal->j_revoke_lock);
 159        list_add(&record->hash, hash_list);
 160        spin_unlock(&journal->j_revoke_lock);
 161        return 0;
 162
 163oom:
 164        if (!journal_oom_retry)
 165                return -ENOMEM;
 166        jbd_debug(1, "ENOMEM in %s, retrying\n", __func__);
 167        yield();
 168        goto repeat;
 169}
 170
 171/* Find a revoke record in the journal's hash table. */
 172
 173static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal,
 174                                                      unsigned long long blocknr)
 175{
 176        struct list_head *hash_list;
 177        struct jbd2_revoke_record_s *record;
 178
 179        hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)];
 180
 181        spin_lock(&journal->j_revoke_lock);
 182        record = (struct jbd2_revoke_record_s *) hash_list->next;
 183        while (&(record->hash) != hash_list) {
 184                if (record->blocknr == blocknr) {
 185                        spin_unlock(&journal->j_revoke_lock);
 186                        return record;
 187                }
 188                record = (struct jbd2_revoke_record_s *) record->hash.next;
 189        }
 190        spin_unlock(&journal->j_revoke_lock);
 191        return NULL;
 192}
 193
 194void jbd2_journal_destroy_revoke_caches(void)
 195{
 196        if (jbd2_revoke_record_cache) {
 197                kmem_cache_destroy(jbd2_revoke_record_cache);
 198                jbd2_revoke_record_cache = NULL;
 199        }
 200        if (jbd2_revoke_table_cache) {
 201                kmem_cache_destroy(jbd2_revoke_table_cache);
 202                jbd2_revoke_table_cache = NULL;
 203        }
 204}
 205
 206int __init jbd2_journal_init_revoke_caches(void)
 207{
 208        J_ASSERT(!jbd2_revoke_record_cache);
 209        J_ASSERT(!jbd2_revoke_table_cache);
 210
 211        jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s,
 212                                        SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY);
 213        if (!jbd2_revoke_record_cache)
 214                goto record_cache_failure;
 215
 216        jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s,
 217                                             SLAB_TEMPORARY);
 218        if (!jbd2_revoke_table_cache)
 219                goto table_cache_failure;
 220        return 0;
 221table_cache_failure:
 222        jbd2_journal_destroy_revoke_caches();
 223record_cache_failure:
 224                return -ENOMEM;
 225}
 226
 227static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size)
 228{
 229        int shift = 0;
 230        int tmp = hash_size;
 231        struct jbd2_revoke_table_s *table;
 232
 233        table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL);
 234        if (!table)
 235                goto out;
 236
 237        while((tmp >>= 1UL) != 0UL)
 238                shift++;
 239
 240        table->hash_size = hash_size;
 241        table->hash_shift = shift;
 242        table->hash_table =
 243                kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL);
 244        if (!table->hash_table) {
 245                kmem_cache_free(jbd2_revoke_table_cache, table);
 246                table = NULL;
 247                goto out;
 248        }
 249
 250        for (tmp = 0; tmp < hash_size; tmp++)
 251                INIT_LIST_HEAD(&table->hash_table[tmp]);
 252
 253out:
 254        return table;
 255}
 256
 257static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table)
 258{
 259        int i;
 260        struct list_head *hash_list;
 261
 262        for (i = 0; i < table->hash_size; i++) {
 263                hash_list = &table->hash_table[i];
 264                J_ASSERT(list_empty(hash_list));
 265        }
 266
 267        kfree(table->hash_table);
 268        kmem_cache_free(jbd2_revoke_table_cache, table);
 269}
 270
 271/* Initialise the revoke table for a given journal to a given size. */
 272int jbd2_journal_init_revoke(journal_t *journal, int hash_size)
 273{
 274        J_ASSERT(journal->j_revoke_table[0] == NULL);
 275        J_ASSERT(is_power_of_2(hash_size));
 276
 277        journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size);
 278        if (!journal->j_revoke_table[0])
 279                goto fail0;
 280
 281        journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size);
 282        if (!journal->j_revoke_table[1])
 283                goto fail1;
 284
 285        journal->j_revoke = journal->j_revoke_table[1];
 286
 287        spin_lock_init(&journal->j_revoke_lock);
 288
 289        return 0;
 290
 291fail1:
 292        jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
 293fail0:
 294        return -ENOMEM;
 295}
 296
 297/* Destroy a journal's revoke table.  The table must already be empty! */
 298void jbd2_journal_destroy_revoke(journal_t *journal)
 299{
 300        journal->j_revoke = NULL;
 301        if (journal->j_revoke_table[0])
 302                jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]);
 303        if (journal->j_revoke_table[1])
 304                jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]);
 305}
 306
 307
 308#ifdef __KERNEL__
 309
 310/*
 311 * jbd2_journal_revoke: revoke a given buffer_head from the journal.  This
 312 * prevents the block from being replayed during recovery if we take a
 313 * crash after this current transaction commits.  Any subsequent
 314 * metadata writes of the buffer in this transaction cancel the
 315 * revoke.
 316 *
 317 * Note that this call may block --- it is up to the caller to make
 318 * sure that there are no further calls to journal_write_metadata
 319 * before the revoke is complete.  In ext3, this implies calling the
 320 * revoke before clearing the block bitmap when we are deleting
 321 * metadata.
 322 *
 323 * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a
 324 * parameter, but does _not_ forget the buffer_head if the bh was only
 325 * found implicitly.
 326 *
 327 * bh_in may not be a journalled buffer - it may have come off
 328 * the hash tables without an attached journal_head.
 329 *
 330 * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count
 331 * by one.
 332 */
 333
 334int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr,
 335                   struct buffer_head *bh_in)
 336{
 337        struct buffer_head *bh = NULL;
 338        journal_t *journal;
 339        struct block_device *bdev;
 340        int err;
 341
 342        might_sleep();
 343        if (bh_in)
 344                BUFFER_TRACE(bh_in, "enter");
 345
 346        journal = handle->h_transaction->t_journal;
 347        if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){
 348                J_ASSERT (!"Cannot set revoke feature!");
 349                return -EINVAL;
 350        }
 351
 352        bdev = journal->j_fs_dev;
 353        bh = bh_in;
 354
 355        if (!bh) {
 356                bh = __find_get_block(bdev, blocknr, journal->j_blocksize);
 357                if (bh)
 358                        BUFFER_TRACE(bh, "found on hash");
 359        }
 360#ifdef JBD2_EXPENSIVE_CHECKING
 361        else {
 362                struct buffer_head *bh2;
 363
 364                /* If there is a different buffer_head lying around in
 365                 * memory anywhere... */
 366                bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize);
 367                if (bh2) {
 368                        /* ... and it has RevokeValid status... */
 369                        if (bh2 != bh && buffer_revokevalid(bh2))
 370                                /* ...then it better be revoked too,
 371                                 * since it's illegal to create a revoke
 372                                 * record against a buffer_head which is
 373                                 * not marked revoked --- that would
 374                                 * risk missing a subsequent revoke
 375                                 * cancel. */
 376                                J_ASSERT_BH(bh2, buffer_revoked(bh2));
 377                        put_bh(bh2);
 378                }
 379        }
 380#endif
 381
 382        /* We really ought not ever to revoke twice in a row without
 383           first having the revoke cancelled: it's illegal to free a
 384           block twice without allocating it in between! */
 385        if (bh) {
 386                if (!J_EXPECT_BH(bh, !buffer_revoked(bh),
 387                                 "inconsistent data on disk")) {
 388                        if (!bh_in)
 389                                brelse(bh);
 390                        return -EIO;
 391                }
 392                set_buffer_revoked(bh);
 393                set_buffer_revokevalid(bh);
 394                if (bh_in) {
 395                        BUFFER_TRACE(bh_in, "call jbd2_journal_forget");
 396                        jbd2_journal_forget(handle, bh_in);
 397                } else {
 398                        BUFFER_TRACE(bh, "call brelse");
 399                        __brelse(bh);
 400                }
 401        }
 402
 403        jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in);
 404        err = insert_revoke_hash(journal, blocknr,
 405                                handle->h_transaction->t_tid);
 406        BUFFER_TRACE(bh_in, "exit");
 407        return err;
 408}
 409
 410/*
 411 * Cancel an outstanding revoke.  For use only internally by the
 412 * journaling code (called from jbd2_journal_get_write_access).
 413 *
 414 * We trust buffer_revoked() on the buffer if the buffer is already
 415 * being journaled: if there is no revoke pending on the buffer, then we
 416 * don't do anything here.
 417 *
 418 * This would break if it were possible for a buffer to be revoked and
 419 * discarded, and then reallocated within the same transaction.  In such
 420 * a case we would have lost the revoked bit, but when we arrived here
 421 * the second time we would still have a pending revoke to cancel.  So,
 422 * do not trust the Revoked bit on buffers unless RevokeValid is also
 423 * set.
 424 */
 425int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh)
 426{
 427        struct jbd2_revoke_record_s *record;
 428        journal_t *journal = handle->h_transaction->t_journal;
 429        int need_cancel;
 430        int did_revoke = 0;     /* akpm: debug */
 431        struct buffer_head *bh = jh2bh(jh);
 432
 433        jbd_debug(4, "journal_head %p, cancelling revoke\n", jh);
 434
 435        /* Is the existing Revoke bit valid?  If so, we trust it, and
 436         * only perform the full cancel if the revoke bit is set.  If
 437         * not, we can't trust the revoke bit, and we need to do the
 438         * full search for a revoke record. */
 439        if (test_set_buffer_revokevalid(bh)) {
 440                need_cancel = test_clear_buffer_revoked(bh);
 441        } else {
 442                need_cancel = 1;
 443                clear_buffer_revoked(bh);
 444        }
 445
 446        if (need_cancel) {
 447                record = find_revoke_record(journal, bh->b_blocknr);
 448                if (record) {
 449                        jbd_debug(4, "cancelled existing revoke on "
 450                                  "blocknr %llu\n", (unsigned long long)bh->b_blocknr);
 451                        spin_lock(&journal->j_revoke_lock);
 452                        list_del(&record->hash);
 453                        spin_unlock(&journal->j_revoke_lock);
 454                        kmem_cache_free(jbd2_revoke_record_cache, record);
 455                        did_revoke = 1;
 456                }
 457        }
 458
 459#ifdef JBD2_EXPENSIVE_CHECKING
 460        /* There better not be one left behind by now! */
 461        record = find_revoke_record(journal, bh->b_blocknr);
 462        J_ASSERT_JH(jh, record == NULL);
 463#endif
 464
 465        /* Finally, have we just cleared revoke on an unhashed
 466         * buffer_head?  If so, we'd better make sure we clear the
 467         * revoked status on any hashed alias too, otherwise the revoke
 468         * state machine will get very upset later on. */
 469        if (need_cancel) {
 470                struct buffer_head *bh2;
 471                bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size);
 472                if (bh2) {
 473                        if (bh2 != bh)
 474                                clear_buffer_revoked(bh2);
 475                        __brelse(bh2);
 476                }
 477        }
 478        return did_revoke;
 479}
 480
 481/*
 482 * journal_clear_revoked_flag clears revoked flag of buffers in
 483 * revoke table to reflect there is no revoked buffers in the next
 484 * transaction which is going to be started.
 485 */
 486void jbd2_clear_buffer_revoked_flags(journal_t *journal)
 487{
 488        struct jbd2_revoke_table_s *revoke = journal->j_revoke;
 489        int i = 0;
 490
 491        for (i = 0; i < revoke->hash_size; i++) {
 492                struct list_head *hash_list;
 493                struct list_head *list_entry;
 494                hash_list = &revoke->hash_table[i];
 495
 496                list_for_each(list_entry, hash_list) {
 497                        struct jbd2_revoke_record_s *record;
 498                        struct buffer_head *bh;
 499                        record = (struct jbd2_revoke_record_s *)list_entry;
 500                        bh = __find_get_block(journal->j_fs_dev,
 501                                              record->blocknr,
 502                                              journal->j_blocksize);
 503                        if (bh) {
 504                                clear_buffer_revoked(bh);
 505                                __brelse(bh);
 506                        }
 507                }
 508        }
 509}
 510
 511/* journal_switch_revoke table select j_revoke for next transaction
 512 * we do not want to suspend any processing until all revokes are
 513 * written -bzzz
 514 */
 515void jbd2_journal_switch_revoke_table(journal_t *journal)
 516{
 517        int i;
 518
 519        if (journal->j_revoke == journal->j_revoke_table[0])
 520                journal->j_revoke = journal->j_revoke_table[1];
 521        else
 522                journal->j_revoke = journal->j_revoke_table[0];
 523
 524        for (i = 0; i < journal->j_revoke->hash_size; i++)
 525                INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]);
 526}
 527
 528/*
 529 * Write revoke records to the journal for all entries in the current
 530 * revoke hash, deleting the entries as we go.
 531 */
 532void jbd2_journal_write_revoke_records(journal_t *journal,
 533                                       transaction_t *transaction,
 534                                       int write_op)
 535{
 536        struct journal_head *descriptor;
 537        struct jbd2_revoke_record_s *record;
 538        struct jbd2_revoke_table_s *revoke;
 539        struct list_head *hash_list;
 540        int i, offset, count;
 541
 542        descriptor = NULL;
 543        offset = 0;
 544        count = 0;
 545
 546        /* select revoke table for committing transaction */
 547        revoke = journal->j_revoke == journal->j_revoke_table[0] ?
 548                journal->j_revoke_table[1] : journal->j_revoke_table[0];
 549
 550        for (i = 0; i < revoke->hash_size; i++) {
 551                hash_list = &revoke->hash_table[i];
 552
 553                while (!list_empty(hash_list)) {
 554                        record = (struct jbd2_revoke_record_s *)
 555                                hash_list->next;
 556                        write_one_revoke_record(journal, transaction,
 557                                                &descriptor, &offset,
 558                                                record, write_op);
 559                        count++;
 560                        list_del(&record->hash);
 561                        kmem_cache_free(jbd2_revoke_record_cache, record);
 562                }
 563        }
 564        if (descriptor)
 565                flush_descriptor(journal, descriptor, offset, write_op);
 566        jbd_debug(1, "Wrote %d revoke records\n", count);
 567}
 568
 569/*
 570 * Write out one revoke record.  We need to create a new descriptor
 571 * block if the old one is full or if we have not already created one.
 572 */
 573
 574static void write_one_revoke_record(journal_t *journal,
 575                                    transaction_t *transaction,
 576                                    struct journal_head **descriptorp,
 577                                    int *offsetp,
 578                                    struct jbd2_revoke_record_s *record,
 579                                    int write_op)
 580{
 581        int csum_size = 0;
 582        struct journal_head *descriptor;
 583        int offset;
 584        journal_header_t *header;
 585
 586        /* If we are already aborting, this all becomes a noop.  We
 587           still need to go round the loop in
 588           jbd2_journal_write_revoke_records in order to free all of the
 589           revoke records: only the IO to the journal is omitted. */
 590        if (is_journal_aborted(journal))
 591                return;
 592
 593        descriptor = *descriptorp;
 594        offset = *offsetp;
 595
 596        /* Do we need to leave space at the end for a checksum? */
 597        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 598                csum_size = sizeof(struct jbd2_journal_revoke_tail);
 599
 600        /* Make sure we have a descriptor with space left for the record */
 601        if (descriptor) {
 602                if (offset >= journal->j_blocksize - csum_size) {
 603                        flush_descriptor(journal, descriptor, offset, write_op);
 604                        descriptor = NULL;
 605                }
 606        }
 607
 608        if (!descriptor) {
 609                descriptor = jbd2_journal_get_descriptor_buffer(journal);
 610                if (!descriptor)
 611                        return;
 612                header = (journal_header_t *) &jh2bh(descriptor)->b_data[0];
 613                header->h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
 614                header->h_blocktype = cpu_to_be32(JBD2_REVOKE_BLOCK);
 615                header->h_sequence  = cpu_to_be32(transaction->t_tid);
 616
 617                /* Record it so that we can wait for IO completion later */
 618                JBUFFER_TRACE(descriptor, "file as BJ_LogCtl");
 619                jbd2_journal_file_buffer(descriptor, transaction, BJ_LogCtl);
 620
 621                offset = sizeof(jbd2_journal_revoke_header_t);
 622                *descriptorp = descriptor;
 623        }
 624
 625        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) {
 626                * ((__be64 *)(&jh2bh(descriptor)->b_data[offset])) =
 627                        cpu_to_be64(record->blocknr);
 628                offset += 8;
 629
 630        } else {
 631                * ((__be32 *)(&jh2bh(descriptor)->b_data[offset])) =
 632                        cpu_to_be32(record->blocknr);
 633                offset += 4;
 634        }
 635
 636        *offsetp = offset;
 637}
 638
 639static void jbd2_revoke_csum_set(journal_t *j,
 640                                 struct journal_head *descriptor)
 641{
 642        struct jbd2_journal_revoke_tail *tail;
 643        __u32 csum;
 644
 645        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 646                return;
 647
 648        tail = (struct jbd2_journal_revoke_tail *)
 649                        (jh2bh(descriptor)->b_data + j->j_blocksize -
 650                        sizeof(struct jbd2_journal_revoke_tail));
 651        tail->r_checksum = 0;
 652        csum = jbd2_chksum(j, j->j_csum_seed, jh2bh(descriptor)->b_data,
 653                           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 journal_head *descriptor,
 666                             int offset, int write_op)
 667{
 668        jbd2_journal_revoke_header_t *header;
 669        struct buffer_head *bh = jh2bh(descriptor);
 670
 671        if (is_journal_aborted(journal)) {
 672                put_bh(bh);
 673                return;
 674        }
 675
 676        header = (jbd2_journal_revoke_header_t *) jh2bh(descriptor)->b_data;
 677        header->r_count = cpu_to_be32(offset);
 678        jbd2_revoke_csum_set(journal, descriptor);
 679
 680        set_buffer_jwrite(bh);
 681        BUFFER_TRACE(bh, "write");
 682        set_buffer_dirty(bh);
 683        write_dirty_buffer(bh, write_op);
 684}
 685#endif
 686
 687/*
 688 * Revoke support for recovery.
 689 *
 690 * Recovery needs to be able to:
 691 *
 692 *  record all revoke records, including the tid of the latest instance
 693 *  of each revoke in the journal
 694 *
 695 *  check whether a given block in a given transaction should be replayed
 696 *  (ie. has not been revoked by a revoke record in that or a subsequent
 697 *  transaction)
 698 *
 699 *  empty the revoke table after recovery.
 700 */
 701
 702/*
 703 * First, setting revoke records.  We create a new revoke record for
 704 * every block ever revoked in the log as we scan it for recovery, and
 705 * we update the existing records if we find multiple revokes for a
 706 * single block.
 707 */
 708
 709int jbd2_journal_set_revoke(journal_t *journal,
 710                       unsigned long long blocknr,
 711                       tid_t sequence)
 712{
 713        struct jbd2_revoke_record_s *record;
 714
 715        record = find_revoke_record(journal, blocknr);
 716        if (record) {
 717                /* If we have multiple occurrences, only record the
 718                 * latest sequence number in the hashed record */
 719                if (tid_gt(sequence, record->sequence))
 720                        record->sequence = sequence;
 721                return 0;
 722        }
 723        return insert_revoke_hash(journal, blocknr, sequence);
 724}
 725
 726/*
 727 * Test revoke records.  For a given block referenced in the log, has
 728 * that block been revoked?  A revoke record with a given transaction
 729 * sequence number revokes all blocks in that transaction and earlier
 730 * ones, but later transactions still need replayed.
 731 */
 732
 733int jbd2_journal_test_revoke(journal_t *journal,
 734                        unsigned long long blocknr,
 735                        tid_t sequence)
 736{
 737        struct jbd2_revoke_record_s *record;
 738
 739        record = find_revoke_record(journal, blocknr);
 740        if (!record)
 741                return 0;
 742        if (tid_gt(sequence, record->sequence))
 743                return 0;
 744        return 1;
 745}
 746
 747/*
 748 * Finally, once recovery is over, we need to clear the revoke table so
 749 * that it can be reused by the running filesystem.
 750 */
 751
 752void jbd2_journal_clear_revoke(journal_t *journal)
 753{
 754        int i;
 755        struct list_head *hash_list;
 756        struct jbd2_revoke_record_s *record;
 757        struct jbd2_revoke_table_s *revoke;
 758
 759        revoke = journal->j_revoke;
 760
 761        for (i = 0; i < revoke->hash_size; i++) {
 762                hash_list = &revoke->hash_table[i];
 763                while (!list_empty(hash_list)) {
 764                        record = (struct jbd2_revoke_record_s*) hash_list->next;
 765                        list_del(&record->hash);
 766                        kmem_cache_free(jbd2_revoke_record_cache, record);
 767                }
 768        }
 769}
 770
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.