fs/jbd2/checkpoint.c

   1 /*
   2  * linux/fs/jbd2/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/jbd2.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 static inline void __buffer_unlink_first(struct journal_head *jh)
  32 {
  33         transaction_t *transaction = jh->b_cp_transaction;
  34
  35         jh->b_cpnext->b_cpprev = jh->b_cpprev;
  36         jh->b_cpprev->b_cpnext = jh->b_cpnext;
  37         if (transaction->t_checkpoint_list == jh) {
  38                 transaction->t_checkpoint_list = jh->b_cpnext;
  39                 if (transaction->t_checkpoint_list == jh)
  40                         transaction->t_checkpoint_list = NULL;
  41         }
  42 }
  43
  44 /*
  45  * Unlink a buffer from a transaction checkpoint(io) list.
  46  *
  47  * Called with j_list_lock held.
  48  */
  49 static inline void __buffer_unlink(struct journal_head *jh)
  50 {
  51         transaction_t *transaction = jh->b_cp_transaction;
  52
  53         __buffer_unlink_first(jh);
  54         if (transaction->t_checkpoint_io_list == jh) {
  55                 transaction->t_checkpoint_io_list = jh->b_cpnext;
  56                 if (transaction->t_checkpoint_io_list == jh)
  57                         transaction->t_checkpoint_io_list = NULL;
  58         }
  59 }
  60
  61 /*
  62  * Move a buffer from the checkpoint list to the checkpoint io list
  63  *
  64  * Called with j_list_lock held
  65  */
  66 static inline void __buffer_relink_io(struct journal_head *jh)
  67 {
  68         transaction_t *transaction = jh->b_cp_transaction;
  69
  70         __buffer_unlink_first(jh);
  71
  72         if (!transaction->t_checkpoint_io_list) {
  73                 jh->b_cpnext = jh->b_cpprev = jh;
  74         } else {
  75                 jh->b_cpnext = transaction->t_checkpoint_io_list;
  76                 jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
  77                 jh->b_cpprev->b_cpnext = jh;
  78                 jh->b_cpnext->b_cpprev = jh;
  79         }
  80         transaction->t_checkpoint_io_list = jh;
  81 }
  82
  83 /*
  84  * Try to release a checkpointed buffer from its transaction.
  85  * Returns 1 if we released it and 2 if we also released the
  86  * whole transaction.
  87  *
  88  * Requires j_list_lock
  89  * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
  90  */
  91 static int __try_to_free_cp_buf(struct journal_head *jh)
  92 {
  93         int ret = 0;
  94         struct buffer_head *bh = jh2bh(jh);
  95
  96         if (jh->b_jlist == BJ_None && !buffer_locked(bh) && !buffer_dirty(bh)) {
  97                 JBUFFER_TRACE(jh, "remove from checkpoint list");
  98                 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
  99                 jbd_unlock_bh_state(bh);
 100                 jbd2_journal_remove_journal_head(bh);
 101                 BUFFER_TRACE(bh, "release");
 102                 __brelse(bh);
 103         } else {
 104                 jbd_unlock_bh_state(bh);
 105         }
 106         return ret;
 107 }
 108
 109 /*
 110  * __jbd2_log_wait_for_space: wait until there is space in the journal.
 111  *
 112  * Called under j-state_lock *only*.  It will be unlocked if we have to wait
 113  * for a checkpoint to free up some space in the log.
 114  */
 115 void __jbd2_log_wait_for_space(journal_t *journal)
 116 {
 117         int nblocks;
 118         assert_spin_locked(&journal->j_state_lock);
 119
 120         nblocks = jbd_space_needed(journal);
 121         while (__jbd2_log_space_left(journal) < nblocks) {
 122                 if (journal->j_flags & JBD2_ABORT)
 123                         return;
 124                 spin_unlock(&journal->j_state_lock);
 125                 mutex_lock(&journal->j_checkpoint_mutex);
 126
 127                 /*
 128                  * Test again, another process may have checkpointed while we
 129                  * were waiting for the checkpoint lock. If there are no
 130                  * outstanding transactions there is nothing to checkpoint and
 131                  * we can't make progress. Abort the journal in this case.
 132                  */
 133                 spin_lock(&journal->j_state_lock);
 134                 spin_lock(&journal->j_list_lock);
 135                 nblocks = jbd_space_needed(journal);
 136                 if (__jbd2_log_space_left(journal) < nblocks) {
 137                         int chkpt = journal->j_checkpoint_transactions != NULL;
 138
 139                         spin_unlock(&journal->j_list_lock);
 140                         spin_unlock(&journal->j_state_lock);
 141                         if (chkpt) {
 142                                 jbd2_log_do_checkpoint(journal);
 143                         } else {
 144                                 printk(KERN_ERR "%s: no transactions\n",
 145                                        __func__);
 146                                 jbd2_journal_abort(journal, 0);
 147                         }
 148
 149                         spin_lock(&journal->j_state_lock);
 150                 } else {
 151                         spin_unlock(&journal->j_list_lock);
 152                 }
 153                 mutex_unlock(&journal->j_checkpoint_mutex);
 154         }
 155 }
 156
 157 /*
 158  * We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
 159  * The caller must restart a list walk.  Wait for someone else to run
 160  * jbd_unlock_bh_state().
 161  */
 162 static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
 163         __releases(journal->j_list_lock)
 164 {
 165         get_bh(bh);
 166         spin_unlock(&journal->j_list_lock);
 167         jbd_lock_bh_state(bh);
 168         jbd_unlock_bh_state(bh);
 169         put_bh(bh);
 170 }
 171
 172 /*
 173  * Clean up transaction's list of buffers submitted for io.
 174  * We wait for any pending IO to complete and remove any clean
 175  * buffers. Note that we take the buffers in the opposite ordering
 176  * from the one in which they were submitted for IO.
 177  *
 178  * Called with j_list_lock held.
 179  */
 180 static void __wait_cp_io(journal_t *journal, transaction_t *transaction)
 181 {
 182         struct journal_head *jh;
 183         struct buffer_head *bh;
 184         tid_t this_tid;
 185         int released = 0;
 186
 187         this_tid = transaction->t_tid;
 188 restart:
 189         /* Did somebody clean up the transaction in the meanwhile? */
 190         if (journal->j_checkpoint_transactions != transaction ||
 191                         transaction->t_tid != this_tid)
 192                 return;
 193         while (!released && transaction->t_checkpoint_io_list) {
 194                 jh = transaction->t_checkpoint_io_list;
 195                 bh = jh2bh(jh);
 196                 if (!jbd_trylock_bh_state(bh)) {
 197                         jbd_sync_bh(journal, bh);
 198                         spin_lock(&journal->j_list_lock);
 199                         goto restart;
 200                 }
 201                 if (buffer_locked(bh)) {
 202                         atomic_inc(&bh->b_count);
 203                         spin_unlock(&journal->j_list_lock);
 204                         jbd_unlock_bh_state(bh);
 205                         wait_on_buffer(bh);
 206                         /* the journal_head may have gone by now */
 207                         BUFFER_TRACE(bh, "brelse");
 208                         __brelse(bh);
 209                         spin_lock(&journal->j_list_lock);
 210                         goto restart;
 211                 }
 212                 /*
 213                  * Now in whatever state the buffer currently is, we know that
 214                  * it has been written out and so we can drop it from the list
 215                  */
 216                 released = __jbd2_journal_remove_checkpoint(jh);
 217                 jbd_unlock_bh_state(bh);
 218                 jbd2_journal_remove_journal_head(bh);
 219                 __brelse(bh);
 220         }
 221 }
 222
 223 #define NR_BATCH        64
 224
 225 static void
 226 __flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
 227 {
 228         int i;
 229
 230         ll_rw_block(SWRITE, *batch_count, bhs);
 231         for (i = 0; i < *batch_count; i++) {
 232                 struct buffer_head *bh = bhs[i];
 233                 clear_buffer_jwrite(bh);
 234                 BUFFER_TRACE(bh, "brelse");
 235                 __brelse(bh);
 236         }
 237         *batch_count = 0;
 238 }
 239
 240 /*
 241  * Try to flush one buffer from the checkpoint list to disk.
 242  *
 243  * Return 1 if something happened which requires us to abort the current
 244  * scan of the checkpoint list.
 245  *
 246  * Called with j_list_lock held and drops it if 1 is returned
 247  * Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
 248  */
 249 static int __process_buffer(journal_t *journal, struct journal_head *jh,
 250                         struct buffer_head **bhs, int *batch_count,
 251                         transaction_t *transaction)
 252 {
 253         struct buffer_head *bh = jh2bh(jh);
 254         int ret = 0;
 255
 256         if (buffer_locked(bh)) {
 257                 atomic_inc(&bh->b_count);
 258                 spin_unlock(&journal->j_list_lock);
 259                 jbd_unlock_bh_state(bh);
 260                 wait_on_buffer(bh);
 261                 /* the journal_head may have gone by now */
 262                 BUFFER_TRACE(bh, "brelse");
 263                 __brelse(bh);
 264                 ret = 1;
 265         } else if (jh->b_transaction != NULL) {
 266                 transaction_t *t = jh->b_transaction;
 267                 tid_t tid = t->t_tid;
 268
 269                 transaction->t_chp_stats.cs_forced_to_close++;
 270                 spin_unlock(&journal->j_list_lock);
 271                 jbd_unlock_bh_state(bh);
 272                 jbd2_log_start_commit(journal, tid);
 273                 jbd2_log_wait_commit(journal, tid);
 274                 ret = 1;
 275         } else if (!buffer_dirty(bh)) {
 276                 J_ASSERT_JH(jh, !buffer_jbddirty(bh));
 277                 BUFFER_TRACE(bh, "remove from checkpoint");
 278                 __jbd2_journal_remove_checkpoint(jh);
 279                 spin_unlock(&journal->j_list_lock);
 280                 jbd_unlock_bh_state(bh);
 281                 jbd2_journal_remove_journal_head(bh);
 282                 __brelse(bh);
 283                 ret = 1;
 284         } else {
 285                 /*
 286                  * Important: we are about to write the buffer, and
 287                  * possibly block, while still holding the journal lock.
 288                  * We cannot afford to let the transaction logic start
 289                  * messing around with this buffer before we write it to
 290                  * disk, as that would break recoverability.
 291                  */
 292                 BUFFER_TRACE(bh, "queue");
 293                 get_bh(bh);
 294                 J_ASSERT_BH(bh, !buffer_jwrite(bh));
 295                 set_buffer_jwrite(bh);
 296                 bhs[*batch_count] = bh;
 297                 __buffer_relink_io(jh);
 298                 jbd_unlock_bh_state(bh);
 299                 transaction->t_chp_stats.cs_written++;
 300                 (*batch_count)++;
 301                 if (*batch_count == NR_BATCH) {
 302                         spin_unlock(&journal->j_list_lock);
 303                         __flush_batch(journal, bhs, batch_count);
 304                         ret = 1;
 305                 }
 306         }
 307         return ret;
 308 }
 309
 310 /*
 311  * Perform an actual checkpoint. We take the first transaction on the
 312  * list of transactions to be checkpointed and send all its buffers
 313  * to disk. We submit larger chunks of data at once.
 314  *
 315  * The journal should be locked before calling this function.
 316  */
 317 int jbd2_log_do_checkpoint(journal_t *journal)
 318 {
 319         transaction_t *transaction;
 320         tid_t this_tid;
 321         int result;
 322
 323         jbd_debug(1, "Start checkpoint\n");
 324
 325         /*
 326          * First thing: if there are any transactions in the log which
 327          * don't need checkpointing, just eliminate them from the
 328          * journal straight away.
 329          */
 330         result = jbd2_cleanup_journal_tail(journal);
 331         jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
 332         if (result <= 0)
 333                 return result;
 334
 335         /*
 336          * OK, we need to start writing disk blocks.  Take one transaction
 337          * and write it.
 338          */
 339         spin_lock(&journal->j_list_lock);
 340         if (!journal->j_checkpoint_transactions)
 341                 goto out;
 342         transaction = journal->j_checkpoint_transactions;
 343         if (transaction->t_chp_stats.cs_chp_time == 0)
 344                 transaction->t_chp_stats.cs_chp_time = jiffies;
 345         this_tid = transaction->t_tid;
 346 restart:
 347         /*
 348          * If someone cleaned up this transaction while we slept, we're
 349          * done (maybe it's a new transaction, but it fell at the same
 350          * address).
 351          */
 352         if (journal->j_checkpoint_transactions == transaction &&
 353                         transaction->t_tid == this_tid) {
 354                 int batch_count = 0;
 355                 struct buffer_head *bhs[NR_BATCH];
 356                 struct journal_head *jh;
 357                 int retry = 0;
 358
 359                 while (!retry && transaction->t_checkpoint_list) {
 360                         struct buffer_head *bh;
 361
 362                         jh = transaction->t_checkpoint_list;
 363                         bh = jh2bh(jh);
 364                         if (!jbd_trylock_bh_state(bh)) {
 365                                 jbd_sync_bh(journal, bh);
 366                                 retry = 1;
 367                                 break;
 368                         }
 369                         retry = __process_buffer(journal, jh, bhs, &batch_count,
 370                                                  transaction);
 371                         if (!retry && (need_resched() ||
 372                                 spin_needbreak(&journal->j_list_lock))) {
 373                                 spin_unlock(&journal->j_list_lock);
 374                                 retry = 1;
 375                                 break;
 376                         }
 377                 }
 378
 379                 if (batch_count) {
 380                         if (!retry) {
 381                                 spin_unlock(&journal->j_list_lock);
 382                                 retry = 1;
 383                         }
 384                         __flush_batch(journal, bhs, &batch_count);
 385                 }
 386
 387                 if (retry) {
 388                         spin_lock(&journal->j_list_lock);
 389                         goto restart;
 390                 }
 391                 /*
 392                  * Now we have cleaned up the first transaction's checkpoint
 393                  * list. Let's clean up the second one
 394                  */
 395                 __wait_cp_io(journal, transaction);
 396         }
 397 out:
 398         spin_unlock(&journal->j_list_lock);
 399         result = jbd2_cleanup_journal_tail(journal);
 400         if (result < 0)
 401                 return result;
 402         return 0;
 403 }
 404
 405 /*
 406  * Check the list of checkpoint transactions for the journal to see if
 407  * we have already got rid of any since the last update of the log tail
 408  * in the journal superblock.  If so, we can instantly roll the
 409  * superblock forward to remove those transactions from the log.
 410  *
 411  * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
 412  *
 413  * Called with the journal lock held.
 414  *
 415  * This is the only part of the journaling code which really needs to be
 416  * aware of transaction aborts.  Checkpointing involves writing to the
 417  * main filesystem area rather than to the journal, so it can proceed
 418  * even in abort state, but we must not update the journal superblock if
 419  * we have an abort error outstanding.
 420  */
 421
 422 int jbd2_cleanup_journal_tail(journal_t *journal)
 423 {
 424         transaction_t * transaction;
 425         tid_t           first_tid;
 426         unsigned long   blocknr, freed;
 427
 428         /* OK, work out the oldest transaction remaining in the log, and
 429          * the log block it starts at.
 430          *
 431          * If the log is now empty, we need to work out which is the
 432          * next transaction ID we will write, and where it will
 433          * start. */
 434
 435         spin_lock(&journal->j_state_lock);
 436         spin_lock(&journal->j_list_lock);
 437         transaction = journal->j_checkpoint_transactions;
 438         if (transaction) {
 439                 first_tid = transaction->t_tid;
 440                 blocknr = transaction->t_log_start;
 441         } else if ((transaction = journal->j_committing_transaction) != NULL) {
 442                 first_tid = transaction->t_tid;
 443                 blocknr = transaction->t_log_start;
 444         } else if ((transaction = journal->j_running_transaction) != NULL) {
 445                 first_tid = transaction->t_tid;
 446                 blocknr = journal->j_head;
 447         } else {
 448                 first_tid = journal->j_transaction_sequence;
 449                 blocknr = journal->j_head;
 450         }
 451         spin_unlock(&journal->j_list_lock);
 452         J_ASSERT(blocknr != 0);
 453
 454         /* If the oldest pinned transaction is at the tail of the log
 455            already then there's not much we can do right now. */
 456         if (journal->j_tail_sequence == first_tid) {
 457                 spin_unlock(&journal->j_state_lock);
 458                 return 1;
 459         }
 460
 461         /* OK, update the superblock to recover the freed space.
 462          * Physical blocks come first: have we wrapped beyond the end of
 463          * the log?  */
 464         freed = blocknr - journal->j_tail;
 465         if (blocknr < journal->j_tail)
 466                 freed = freed + journal->j_last - journal->j_first;
 467
 468         jbd_debug(1,
 469                   "Cleaning journal tail from %d to %d (offset %lu), "
 470                   "freeing %lu\n",
 471                   journal->j_tail_sequence, first_tid, blocknr, freed);
 472
 473         journal->j_free += freed;
 474         journal->j_tail_sequence = first_tid;
 475         journal->j_tail = blocknr;
 476         spin_unlock(&journal->j_state_lock);
 477         if (!(journal->j_flags & JBD2_ABORT))
 478                 jbd2_journal_update_superblock(journal, 1);
 479         return 0;
 480 }
 481
 482
 483 /* Checkpoint list management */
 484
 485 /*
 486  * journal_clean_one_cp_list
 487  *
 488  * Find all the written-back checkpoint buffers in the given list and release them.
 489  *
 490  * Called with the journal locked.
 491  * Called with j_list_lock held.
 492  * Returns number of bufers reaped (for debug)
 493  */
 494
 495 static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
 496 {
 497         struct journal_head *last_jh;
 498         struct journal_head *next_jh = jh;
 499         int ret, freed = 0;
 500
 501         *released = 0;
 502         if (!jh)
 503                 return 0;
 504
 505         last_jh = jh->b_cpprev;
 506         do {
 507                 jh = next_jh;
 508                 next_jh = jh->b_cpnext;
 509                 /* Use trylock because of the ranking */
 510                 if (jbd_trylock_bh_state(jh2bh(jh))) {
 511                         ret = __try_to_free_cp_buf(jh);
 512                         if (ret) {
 513                                 freed++;
 514                                 if (ret == 2) {
 515                                         *released = 1;
 516                                         return freed;
 517                                 }
 518                         }
 519                 }
 520                 /*
 521                  * This function only frees up some memory
 522                  * if possible so we dont have an obligation
 523                  * to finish processing. Bail out if preemption
 524                  * requested:
 525                  */
 526                 if (need_resched())
 527                         return freed;
 528         } while (jh != last_jh);
 529
 530         return freed;
 531 }
 532
 533 /*
 534  * journal_clean_checkpoint_list
 535  *
 536  * Find all the written-back checkpoint buffers in the journal and release them.
 537  *
 538  * Called with the journal locked.
 539  * Called with j_list_lock held.
 540  * Returns number of buffers reaped (for debug)
 541  */
 542
 543 int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
 544 {
 545         transaction_t *transaction, *last_transaction, *next_transaction;
 546         int ret = 0;
 547         int released;
 548
 549         transaction = journal->j_checkpoint_transactions;
 550         if (!transaction)
 551                 goto out;
 552
 553         last_transaction = transaction->t_cpprev;
 554         next_transaction = transaction;
 555         do {
 556                 transaction = next_transaction;
 557                 next_transaction = transaction->t_cpnext;
 558                 ret += journal_clean_one_cp_list(transaction->
 559                                 t_checkpoint_list, &released);
 560                 /*
 561                  * This function only frees up some memory if possible so we
 562                  * dont have an obligation to finish processing. Bail out if
 563                  * preemption requested:
 564                  */
 565                 if (need_resched())
 566                         goto out;
 567                 if (released)
 568                         continue;
 569                 /*
 570                  * It is essential that we are as careful as in the case of
 571                  * t_checkpoint_list with removing the buffer from the list as
 572                  * we can possibly see not yet submitted buffers on io_list
 573                  */
 574                 ret += journal_clean_one_cp_list(transaction->
 575                                 t_checkpoint_io_list, &released);
 576                 if (need_resched())
 577                         goto out;
 578         } while (transaction != last_transaction);
 579 out:
 580         return ret;
 581 }
 582
 583 /*
 584  * journal_remove_checkpoint: called after a buffer has been committed
 585  * to disk (either by being write-back flushed to disk, or being
 586  * committed to the log).
 587  *
 588  * We cannot safely clean a transaction out of the log until all of the
 589  * buffer updates committed in that transaction have safely been stored
 590  * elsewhere on disk.  To achieve this, all of the buffers in a
 591  * transaction need to be maintained on the transaction's checkpoint
 592  * lists until they have been rewritten, at which point this function is
 593  * called to remove the buffer from the existing transaction's
 594  * checkpoint lists.
 595  *
 596  * The function returns 1 if it frees the transaction, 0 otherwise.
 597  *
 598  * This function is called with the journal locked.
 599  * This function is called with j_list_lock held.
 600  * This function is called with jbd_lock_bh_state(jh2bh(jh))
 601  */
 602
 603 int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
 604 {
 605         transaction_t *transaction;
 606         journal_t *journal;
 607         int ret = 0;
 608
 609         JBUFFER_TRACE(jh, "entry");
 610
 611         if ((transaction = jh->b_cp_transaction) == NULL) {
 612                 JBUFFER_TRACE(jh, "not on transaction");
 613                 goto out;
 614         }
 615         journal = transaction->t_journal;
 616
 617         __buffer_unlink(jh);
 618         jh->b_cp_transaction = NULL;
 619
 620         if (transaction->t_checkpoint_list != NULL ||
 621             transaction->t_checkpoint_io_list != NULL)
 622                 goto out;
 623         JBUFFER_TRACE(jh, "transaction has no more buffers");
 624
 625         /*
 626          * There is one special case to worry about: if we have just pulled the
 627          * buffer off a running or committing transaction's checkpoing list,
 628          * then even if the checkpoint list is empty, the transaction obviously
 629          * cannot be dropped!
 630          *
 631          * The locking here around t_state is a bit sleazy.
 632          * See the comment at the end of jbd2_journal_commit_transaction().
 633          */
 634         if (transaction->t_state != T_FINISHED) {
 635                 JBUFFER_TRACE(jh, "belongs to running/committing transaction");
 636                 goto out;
 637         }
 638
 639         /* OK, that was the last buffer for the transaction: we can now
 640            safely remove this transaction from the log */
 641
 642         __jbd2_journal_drop_transaction(journal, transaction);
 643
 644         /* Just in case anybody was waiting for more transactions to be
 645            checkpointed... */
 646         wake_up(&journal->j_wait_logspace);
 647         ret = 1;
 648 out:
 649         JBUFFER_TRACE(jh, "exit");
 650         return ret;
 651 }
 652
 653 /*
 654  * journal_insert_checkpoint: put a committed buffer onto a checkpoint
 655  * list so that we know when it is safe to clean the transaction out of
 656  * the log.
 657  *
 658  * Called with the journal locked.
 659  * Called with j_list_lock held.
 660  */
 661 void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
 662                                transaction_t *transaction)
 663 {
 664         JBUFFER_TRACE(jh, "entry");
 665         J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
 666         J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
 667
 668         jh->b_cp_transaction = transaction;
 669
 670         if (!transaction->t_checkpoint_list) {
 671                 jh->b_cpnext = jh->b_cpprev = jh;
 672         } else {
 673                 jh->b_cpnext = transaction->t_checkpoint_list;
 674                 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
 675                 jh->b_cpprev->b_cpnext = jh;
 676                 jh->b_cpnext->b_cpprev = jh;
 677         }
 678         transaction->t_checkpoint_list = jh;
 679 }
 680
 681 /*
 682  * We've finished with this transaction structure: adios...
 683  *
 684  * The transaction must have no links except for the checkpoint by this
 685  * point.
 686  *
 687  * Called with the journal locked.
 688  * Called with j_list_lock held.
 689  */
 690
 691 void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
 692 {
 693         assert_spin_locked(&journal->j_list_lock);
 694         if (transaction->t_cpnext) {
 695                 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
 696                 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
 697                 if (journal->j_checkpoint_transactions == transaction)
 698                         journal->j_checkpoint_transactions =
 699                                 transaction->t_cpnext;
 700                 if (journal->j_checkpoint_transactions == transaction)
 701                         journal->j_checkpoint_transactions = NULL;
 702         }
 703
 704         J_ASSERT(transaction->t_state == T_FINISHED);
 705         J_ASSERT(transaction->t_buffers == NULL);
 706         J_ASSERT(transaction->t_forget == NULL);
 707         J_ASSERT(transaction->t_iobuf_list == NULL);
 708         J_ASSERT(transaction->t_shadow_list == NULL);
 709         J_ASSERT(transaction->t_log_list == NULL);
 710         J_ASSERT(transaction->t_checkpoint_list == NULL);
 711         J_ASSERT(transaction->t_checkpoint_io_list == NULL);
 712         J_ASSERT(transaction->t_updates == 0);
 713         J_ASSERT(journal->j_committing_transaction != transaction);
 714         J_ASSERT(journal->j_running_transaction != transaction);
 715
 716         jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
 717         kfree(transaction);
 718 }