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   1 /*
   2  * linux/fs/checkpoint.c
   3  *
   4  * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
   5  *
   6  * Copyright 1999 Red Hat Software --- 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  * Checkpoint routines for the generic filesystem journaling code.
  13  * Part of the ext2fs journaling system.
  14  *
  15  * Checkpointing is the process of ensuring that a section of the log is
  16  * committed fully to disk, so that that portion of the log can be
  17  * reused.
  18  */
  19
  20 #include <linux/time.h>
  21 #include <linux/fs.h>
  22 #include <linux/jbd.h>
  23 #include <linux/errno.h>
  24 #include <linux/slab.h>
  25
  26 /*
  27  * Unlink a buffer from a transaction checkpoint list.
  28  *
  29  * Called with j_list_lock held.
  30  */
  31
  32 static void __buffer_unlink_first(struct journal_head *jh)
  33 {
  34         transaction_t *transaction;
  35
  36         transaction = jh->b_cp_transaction;
  37
  38         jh->b_cpnext->b_cpprev = jh->b_cpprev;
  39         jh->b_cpprev->b_cpnext = jh->b_cpnext;
  40         if (transaction->t_checkpoint_list == jh) {
  41                 transaction->t_checkpoint_list = jh->b_cpnext;
  42                 if (transaction->t_checkpoint_list == jh)
  43                         transaction->t_checkpoint_list = NULL;
  44         }
  45 }
  46
  47 /*
  48  * Unlink a buffer from a transaction checkpoint(io) list.
  49  *
  50  * Called with j_list_lock held.
  51  */
  52
  53 static inline void __buffer_unlink(struct journal_head *jh)
  54 {
  55         transaction_t *transaction;
  56
  57         transaction = jh->b_cp_transaction;
  58
  59         __buffer_unlink_first(jh);
  60         if (transaction->t_checkpoint_io_list == jh) {
  61                 transaction->t_checkpoint_io_list = jh->b_cpnext;
  62                 if (transaction->t_checkpoint_io_list == jh)
  63                         transaction->t_checkpoint_io_list = NULL;
  64         }
  65 }
  66
  67 /*
  68  * Move a buffer from the checkpoint list to the checkpoint io list
  69  *
  70  * Called with j_list_lock held
  71  */
  72
  73 static inline void __buffer_relink_io(struct journal_head *jh)
  74 {
  75         transaction_t *transaction;
  76
  77         transaction = jh->b_cp_transaction;
  78         __buffer_unlink_first(jh);
  79
  80         if (!transaction->t_checkpoint_io_list) {
  81                 jh->b_cpnext = jh->b_cpprev = jh;
  82         } else {
  83                 jh->b_cpnext = transaction->t_checkpoint_io_list;
  84                 jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
  85                 jh->b_cpprev->b_cpnext = jh;
  86                 jh->b_cpnext->b_cpprev = jh;
  87         }
  88         transaction->t_checkpoint_io_list = jh;
  89 }
  90
  91 /*
  92  * Try to release a checkpointed buffer from its transaction.
  93  * Returns 1 if we released it and 2 if we also released the
  94  * whole transaction.
  95  *
  96  * Requires j_list_lock
  97  * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
  98  */
  99 static int __try_to_free_cp_buf(struct journal_head *jh)
 100 {
 101         int ret = 0;
 102         struct buffer_head *bh = jh2bh(jh);
 103
 104         if (jh->b_jlist == BJ_None && !buffer_locked(bh) && !buffer_dirty(bh)) {
 105                 JBUFFER_TRACE(jh, "remove from checkpoint list");
 106                 ret = __journal_remove_checkpoint(jh) + 1;
 107                 jbd_unlock_bh_state(bh);
 108                 journal_remove_journal_head(bh);
 109                 BUFFER_TRACE(bh, "release");
 110                 __brelse(bh);
 111         } else {
 112                 jbd_unlock_bh_state(bh);
 113         }
 114         return ret;
 115 }
 116
 117 /*
 118  * __log_wait_for_space: wait until there is space in the journal.
 119  *
 120  * Called under j-state_lock *only*.  It will be unlocked if we have to wait
 121  * for a checkpoint to free up some space in the log.
 122  */
 123 void __log_wait_for_space(journal_t *journal)
 124 {
 125         int nblocks;
 126         assert_spin_locked(&journal->j_state_lock);
 127
 128         nblocks = jbd_space_needed(journal);
 129         while (__log_space_left(journal) < nblocks) {
 130                 if (journal->j_flags & JFS_ABORT)
 131                         return;
 132                 spin_unlock(&journal->j_state_lock);
 133                 down(&journal->j_checkpoint_sem);
 134
 135                 /*
 136                  * Test again, another process may have checkpointed while we
 137                  * were waiting for the checkpoint lock
 138                  */
 139                 spin_lock(&journal->j_state_lock);
 140                 nblocks = jbd_space_needed(journal);
 141                 if (__log_space_left(journal) < nblocks) {
 142                         spin_unlock(&journal->j_state_lock);
 143                         log_do_checkpoint(journal);
 144                         spin_lock(&journal->j_state_lock);
 145                 }
 146                 up(&journal->j_checkpoint_sem);
 147         }
 148 }
 149
 150 /*
 151  * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
 152  * The caller must restart a list walk.  Wait for someone else to run
 153  * jbd_unlock_bh_state().
 154  */
 155 static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
 156 {
 157         get_bh(bh);
 158         spin_unlock(&journal->j_list_lock);
 159         jbd_lock_bh_state(bh);
 160         jbd_unlock_bh_state(bh);
 161         put_bh(bh);
 162 }
 163
 164 /*
 165  * Clean up transaction's list of buffers submitted for io.
 166  * We wait for any pending IO to complete and remove any clean
 167  * buffers. Note that we take the buffers in the opposite ordering
 168  * from the one in which they were submitted for IO.
 169  *
 170  * Called with j_list_lock held.
 171  */
 172
 173 static void __wait_cp_io(journal_t *journal, transaction_t *transaction)
 174 {
 175         struct journal_head *jh;
 176         struct buffer_head *bh;
 177         tid_t this_tid;
 178         int released = 0;
 179
 180         this_tid = transaction->t_tid;
 181 restart:
 182         /* Didn't somebody clean up the transaction in the meanwhile */
 183         if (journal->j_checkpoint_transactions != transaction ||
 184                 transaction->t_tid != this_tid)
 185                 return;
 186         while (!released && transaction->t_checkpoint_io_list) {
 187                 jh = transaction->t_checkpoint_io_list;
 188                 bh = jh2bh(jh);
 189                 if (!jbd_trylock_bh_state(bh)) {
 190                         jbd_sync_bh(journal, bh);
 191                         spin_lock(&journal->j_list_lock);
 192                         goto restart;
 193                 }
 194                 if (buffer_locked(bh)) {
 195                         atomic_inc(&bh->b_count);
 196                         spin_unlock(&journal->j_list_lock);
 197                         jbd_unlock_bh_state(bh);
 198                         wait_on_buffer(bh);
 199                         /* the journal_head may have gone by now */
 200                         BUFFER_TRACE(bh, "brelse");
 201                         __brelse(bh);
 202                         spin_lock(&journal->j_list_lock);
 203                         goto restart;
 204                 }
 205                 /*
 206                  * Now in whatever state the buffer currently is, we know that
 207                  * it has been written out and so we can drop it from the list
 208                  */
 209                 released = __journal_remove_checkpoint(jh);
 210                 jbd_unlock_bh_state(bh);
 211         }
 212 }
 213
 214 #define NR_BATCH        64
 215
 216 static void
 217 __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
 218 {
 219         int i;
 220
 221         ll_rw_block(SWRITE, *batch_count, bhs);
 222         for (i = 0; i < *batch_count; i++) {
 223                 struct buffer_head *bh = bhs[i];
 224                 clear_buffer_jwrite(bh);
 225                 BUFFER_TRACE(bh, "brelse");
 226                 __brelse(bh);
 227         }
 228         *batch_count = 0;
 229 }
 230
 231 /*
 232  * Try to flush one buffer from the checkpoint list to disk.
 233  *
 234  * Return 1 if something happened which requires us to abort the current
 235  * scan of the checkpoint list.
 236  *
 237  * Called with j_list_lock held and drops it if 1 is returned
 238  * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
 239  */
 240 static int __process_buffer(journal_t *journal, struct journal_head *jh,
 241                         struct buffer_head **bhs, int *batch_count)
 242 {
 243         struct buffer_head *bh = jh2bh(jh);
 244         int ret = 0;
 245
 246         if (buffer_locked(bh)) {
 247                 get_bh(bh);
 248                 spin_unlock(&journal->j_list_lock);
 249                 jbd_unlock_bh_state(bh);
 250                 wait_on_buffer(bh);
 251                 /* the journal_head may have gone by now */
 252                 BUFFER_TRACE(bh, "brelse");
 253                 put_bh(bh);
 254                 ret = 1;
 255         }
 256         else if (jh->b_transaction != NULL) {
 257                 transaction_t *t = jh->b_transaction;
 258                 tid_t tid = t->t_tid;
 259
 260                 spin_unlock(&journal->j_list_lock);
 261                 jbd_unlock_bh_state(bh);
 262                 log_start_commit(journal, tid);
 263                 log_wait_commit(journal, tid);
 264                 ret = 1;
 265         }
 266         else if (!buffer_dirty(bh)) {
 267                 J_ASSERT_JH(jh, !buffer_jbddirty(bh));
 268                 BUFFER_TRACE(bh, "remove from checkpoint");
 269                 __journal_remove_checkpoint(jh);
 270                 spin_unlock(&journal->j_list_lock);
 271                 jbd_unlock_bh_state(bh);
 272                 journal_remove_journal_head(bh);
 273                 put_bh(bh);
 274                 ret = 1;
 275         }
 276         else {
 277                 /*
 278                  * Important: we are about to write the buffer, and
 279                  * possibly block, while still holding the journal lock.
 280                  * We cannot afford to let the transaction logic start
 281                  * messing around with this buffer before we write it to
 282                  * disk, as that would break recoverability.
 283                  */
 284                 BUFFER_TRACE(bh, "queue");
 285                 get_bh(bh);
 286                 J_ASSERT_BH(bh, !buffer_jwrite(bh));
 287                 set_buffer_jwrite(bh);
 288                 bhs[*batch_count] = bh;
 289                 __buffer_relink_io(jh);
 290                 jbd_unlock_bh_state(bh);
 291                 (*batch_count)++;
 292                 if (*batch_count == NR_BATCH) {
 293                         spin_unlock(&journal->j_list_lock);
 294                         __flush_batch(journal, bhs, batch_count);
 295                         ret = 1;
 296                 }
 297         }
 298         return ret;
 299 }
 300
 301 /*
 302  * Perform an actual checkpoint. We take the first transaction on the
 303  * list of transactions to be checkpointed and send all its buffers
 304  * to disk. We submit larger chunks of data at once.
 305  *
 306  * The journal should be locked before calling this function.
 307  */
 308 int log_do_checkpoint(journal_t *journal)
 309 {
 310         transaction_t *transaction;
 311         tid_t this_tid;
 312         int result;
 313
 314         jbd_debug(1, "Start checkpoint\n");
 315
 316         /*
 317          * First thing: if there are any transactions in the log which
 318          * don't need checkpointing, just eliminate them from the
 319          * journal straight away.
 320          */
 321         result = cleanup_journal_tail(journal);
 322         jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
 323         if (result <= 0)
 324                 return result;
 325
 326         /*
 327          * OK, we need to start writing disk blocks.  Take one transaction
 328          * and write it.
 329          */
 330         spin_lock(&journal->j_list_lock);
 331         if (!journal->j_checkpoint_transactions)
 332                 goto out;
 333         transaction = journal->j_checkpoint_transactions;
 334         this_tid = transaction->t_tid;
 335 restart:
 336         /*
 337          * If someone cleaned up this transaction while we slept, we're
 338          * done (maybe it's a new transaction, but it fell at the same
 339          * address).
 340          */
 341         if (journal->j_checkpoint_transactions == transaction ||
 342                         transaction->t_tid == this_tid) {
 343                 int batch_count = 0;
 344                 struct buffer_head *bhs[NR_BATCH];
 345                 struct journal_head *jh;
 346                 int retry = 0;
 347
 348                 while (!retry && transaction->t_checkpoint_list) {
 349                         struct buffer_head *bh;
 350
 351                         jh = transaction->t_checkpoint_list;
 352                         bh = jh2bh(jh);
 353                         if (!jbd_trylock_bh_state(bh)) {
 354                                 jbd_sync_bh(journal, bh);
 355                                 retry = 1;
 356                                 break;
 357                         }
 358                         retry = __process_buffer(journal, jh, bhs,
 359                                                 &batch_count);
 360                         if (!retry &&
 361                             lock_need_resched(&journal->j_list_lock)) {
 362                                 spin_unlock(&journal->j_list_lock);
 363                                 retry = 1;
 364                                 break;
 365                         }
 366                 }
 367
 368                 if (batch_count) {
 369                         if (!retry) {
 370                                 spin_unlock(&journal->j_list_lock);
 371                                 retry = 1;
 372                         }
 373                         __flush_batch(journal, bhs, &batch_count);
 374                 }
 375
 376                 if (retry) {
 377                         spin_lock(&journal->j_list_lock);
 378                         goto restart;
 379                 }
 380                 /*
 381                  * Now we have cleaned up the first transaction's checkpoint
 382                  * list.  Let's clean up the second one.
 383                  */
 384                 __wait_cp_io(journal, transaction);
 385         }
 386 out:
 387         spin_unlock(&journal->j_list_lock);
 388         result = cleanup_journal_tail(journal);
 389         if (result < 0)
 390                 return result;
 391         return 0;
 392 }
 393
 394 /*
 395  * Check the list of checkpoint transactions for the journal to see if
 396  * we have already got rid of any since the last update of the log tail
 397  * in the journal superblock.  If so, we can instantly roll the
 398  * superblock forward to remove those transactions from the log.
 399  *
 400  * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
 401  *
 402  * Called with the journal lock held.
 403  *
 404  * This is the only part of the journaling code which really needs to be
 405  * aware of transaction aborts.  Checkpointing involves writing to the
 406  * main filesystem area rather than to the journal, so it can proceed
 407  * even in abort state, but we must not update the journal superblock if
 408  * we have an abort error outstanding.
 409  */
 410
 411 int cleanup_journal_tail(journal_t *journal)
 412 {
 413         transaction_t * transaction;
 414         tid_t           first_tid;
 415         unsigned long   blocknr, freed;
 416
 417         /* OK, work out the oldest transaction remaining in the log, and
 418          * the log block it starts at.
 419          *
 420          * If the log is now empty, we need to work out which is the
 421          * next transaction ID we will write, and where it will
 422          * start. */
 423
 424         spin_lock(&journal->j_state_lock);
 425         spin_lock(&journal->j_list_lock);
 426         transaction = journal->j_checkpoint_transactions;
 427         if (transaction) {
 428                 first_tid = transaction->t_tid;
 429                 blocknr = transaction->t_log_start;
 430         } else if ((transaction = journal->j_committing_transaction) != NULL) {
 431                 first_tid = transaction->t_tid;
 432                 blocknr = transaction->t_log_start;
 433         } else if ((transaction = journal->j_running_transaction) != NULL) {
 434                 first_tid = transaction->t_tid;
 435                 blocknr = journal->j_head;
 436         } else {
 437                 first_tid = journal->j_transaction_sequence;
 438                 blocknr = journal->j_head;
 439         }
 440         spin_unlock(&journal->j_list_lock);
 441         J_ASSERT(blocknr != 0);
 442
 443         /* If the oldest pinned transaction is at the tail of the log
 444            already then there's not much we can do right now. */
 445         if (journal->j_tail_sequence == first_tid) {
 446                 spin_unlock(&journal->j_state_lock);
 447                 return 1;
 448         }
 449
 450         /* OK, update the superblock to recover the freed space.
 451          * Physical blocks come first: have we wrapped beyond the end of
 452          * the log?  */
 453         freed = blocknr - journal->j_tail;
 454         if (blocknr < journal->j_tail)
 455                 freed = freed + journal->j_last - journal->j_first;
 456
 457         jbd_debug(1,
 458                   "Cleaning journal tail from %d to %d (offset %lu), "
 459                   "freeing %lu\n",
 460                   journal->j_tail_sequence, first_tid, blocknr, freed);
 461
 462         journal->j_free += freed;
 463         journal->j_tail_sequence = first_tid;
 464         journal->j_tail = blocknr;
 465         spin_unlock(&journal->j_state_lock);
 466         if (!(journal->j_flags & JFS_ABORT))
 467                 journal_update_superblock(journal, 1);
 468         return 0;
 469 }
 470
 471
 472 /* Checkpoint list management */
 473
 474 /*
 475  * journal_clean_one_cp_list
 476  *
 477  * Find all the written-back checkpoint buffers in the given list and release them.
 478  *
 479  * Called with the journal locked.
 480  * Called with j_list_lock held.
 481  * Returns number of bufers reaped (for debug)
 482  */
 483
 484 static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
 485 {
 486         struct journal_head *last_jh;
 487         struct journal_head *next_jh = jh;
 488         int ret, freed = 0;
 489
 490         *released = 0;
 491         if (!jh)
 492                 return 0;
 493
 494         last_jh = jh->b_cpprev;
 495         do {
 496                 jh = next_jh;
 497                 next_jh = jh->b_cpnext;
 498                 /* Use trylock because of the ranking */
 499                 if (jbd_trylock_bh_state(jh2bh(jh))) {
 500                         ret = __try_to_free_cp_buf(jh);
 501                         if (ret) {
 502                                 freed++;
 503                                 if (ret == 2) {
 504                                         *released = 1;
 505                                         return freed;
 506                                 }
 507                         }
 508                 }
 509                 /*
 510                  * This function only frees up some memory if possible so we
 511                  * dont have an obligation to finish processing. Bail out if
 512                  * preemption requested:
 513                  */
 514                 if (need_resched())
 515                         return freed;
 516         } while (jh != last_jh);
 517
 518         return freed;
 519 }
 520
 521 /*
 522  * journal_clean_checkpoint_list
 523  *
 524  * Find all the written-back checkpoint buffers in the journal and release them.
 525  *
 526  * Called with the journal locked.
 527  * Called with j_list_lock held.
 528  * Returns number of buffers reaped (for debug)
 529  */
 530
 531 int __journal_clean_checkpoint_list(journal_t *journal)
 532 {
 533         transaction_t *transaction, *last_transaction, *next_transaction;
 534         int ret = 0, released;
 535
 536         transaction = journal->j_checkpoint_transactions;
 537         if (!transaction)
 538                 goto out;
 539
 540         last_transaction = transaction->t_cpprev;
 541         next_transaction = transaction;
 542         do {
 543                 transaction = next_transaction;
 544                 next_transaction = transaction->t_cpnext;
 545                 ret += journal_clean_one_cp_list(transaction->
 546                                 t_checkpoint_list, &released);
 547                 if (need_resched())
 548                         goto out;
 549                 if (released)
 550                         continue;
 551                 /*
 552                  * It is essential that we are as careful as in the case of
 553                  * t_checkpoint_list with removing the buffer from the list as
 554                  * we can possibly see not yet submitted buffers on io_list
 555                  */
 556                 ret += journal_clean_one_cp_list(transaction->
 557                                 t_checkpoint_io_list, &released);
 558                 if (need_resched())
 559                         goto out;
 560         } while (transaction != last_transaction);
 561 out:
 562         return ret;
 563 }
 564
 565 /*
 566  * journal_remove_checkpoint: called after a buffer has been committed
 567  * to disk (either by being write-back flushed to disk, or being
 568  * committed to the log).
 569  *
 570  * We cannot safely clean a transaction out of the log until all of the
 571  * buffer updates committed in that transaction have safely been stored
 572  * elsewhere on disk.  To achieve this, all of the buffers in a
 573  * transaction need to be maintained on the transaction's checkpoint
 574  * lists until they have been rewritten, at which point this function is
 575  * called to remove the buffer from the existing transaction's
 576  * checkpoint lists.
 577  *
 578  * The function returns 1 if it frees the transaction, 0 otherwise.
 579  *
 580  * This function is called with the journal locked.
 581  * This function is called with j_list_lock held.
 582  * This function is called with jbd_lock_bh_state(jh2bh(jh))
 583  */
 584
 585 int __journal_remove_checkpoint(struct journal_head *jh)
 586 {
 587         transaction_t *transaction;
 588         journal_t *journal;
 589         int ret = 0;
 590
 591         JBUFFER_TRACE(jh, "entry");
 592
 593         if ((transaction = jh->b_cp_transaction) == NULL) {
 594                 JBUFFER_TRACE(jh, "not on transaction");
 595                 goto out;
 596         }
 597         journal = transaction->t_journal;
 598
 599         __buffer_unlink(jh);
 600         jh->b_cp_transaction = NULL;
 601
 602         if (transaction->t_checkpoint_list != NULL ||
 603             transaction->t_checkpoint_io_list != NULL)
 604                 goto out;
 605         JBUFFER_TRACE(jh, "transaction has no more buffers");
 606
 607         /*
 608          * There is one special case to worry about: if we have just pulled the
 609          * buffer off a committing transaction's forget list, then even if the
 610          * checkpoint list is empty, the transaction obviously cannot be
 611          * dropped!
 612          *
 613          * The locking here around j_committing_transaction is a bit sleazy.
 614          * See the comment at the end of journal_commit_transaction().
 615          */
 616         if (transaction == journal->j_committing_transaction) {
 617                 JBUFFER_TRACE(jh, "belongs to committing transaction");
 618                 goto out;
 619         }
 620
 621         /* OK, that was the last buffer for the transaction: we can now
 622            safely remove this transaction from the log */
 623
 624         __journal_drop_transaction(journal, transaction);
 625
 626         /* Just in case anybody was waiting for more transactions to be
 627            checkpointed... */
 628         wake_up(&journal->j_wait_logspace);
 629         ret = 1;
 630 out:
 631         JBUFFER_TRACE(jh, "exit");
 632         return ret;
 633 }
 634
 635 /*
 636  * journal_insert_checkpoint: put a committed buffer onto a checkpoint
 637  * list so that we know when it is safe to clean the transaction out of
 638  * the log.
 639  *
 640  * Called with the journal locked.
 641  * Called with j_list_lock held.
 642  */
 643 void __journal_insert_checkpoint(struct journal_head *jh,
 644                                transaction_t *transaction)
 645 {
 646         JBUFFER_TRACE(jh, "entry");
 647         J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
 648         J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
 649
 650         jh->b_cp_transaction = transaction;
 651
 652         if (!transaction->t_checkpoint_list) {
 653                 jh->b_cpnext = jh->b_cpprev = jh;
 654         } else {
 655                 jh->b_cpnext = transaction->t_checkpoint_list;
 656                 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
 657                 jh->b_cpprev->b_cpnext = jh;
 658                 jh->b_cpnext->b_cpprev = jh;
 659         }
 660         transaction->t_checkpoint_list = jh;
 661 }
 662
 663 /*
 664  * We've finished with this transaction structure: adios...
 665  *
 666  * The transaction must have no links except for the checkpoint by this
 667  * point.
 668  *
 669  * Called with the journal locked.
 670  * Called with j_list_lock held.
 671  */
 672
 673 void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)
 674 {
 675         assert_spin_locked(&journal->j_list_lock);
 676         if (transaction->t_cpnext) {
 677                 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
 678                 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
 679                 if (journal->j_checkpoint_transactions == transaction)
 680                         journal->j_checkpoint_transactions =
 681                                 transaction->t_cpnext;
 682                 if (journal->j_checkpoint_transactions == transaction)
 683                         journal->j_checkpoint_transactions = NULL;
 684         }
 685
 686         J_ASSERT(transaction->t_state == T_FINISHED);
 687         J_ASSERT(transaction->t_buffers == NULL);
 688         J_ASSERT(transaction->t_sync_datalist == NULL);
 689         J_ASSERT(transaction->t_forget == NULL);
 690         J_ASSERT(transaction->t_iobuf_list == NULL);
 691         J_ASSERT(transaction->t_shadow_list == NULL);
 692         J_ASSERT(transaction->t_log_list == NULL);
 693         J_ASSERT(transaction->t_checkpoint_list == NULL);
 694         J_ASSERT(transaction->t_checkpoint_io_list == NULL);
 695         J_ASSERT(transaction->t_updates == 0);
 696         J_ASSERT(journal->j_committing_transaction != transaction);
 697         J_ASSERT(journal->j_running_transaction != transaction);
 698
 699         jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
 700         kfree(transaction);
 701 }