fs/jbd2/checkpoint.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * linux/fs/jbd2/checkpoint.c
   4  *
   5  * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
   6  *
   7  * Copyright 1999 Red Hat Software --- All Rights Reserved
   8  *
   9  * Checkpoint routines for the generic filesystem journaling code.
  10  * Part of the ext2fs journaling system.
  11  *
  12  * Checkpointing is the process of ensuring that a section of the log is
  13  * committed fully to disk, so that that portion of the log can be
  14  * reused.
  15  */
  16
  17 #include <linux/time.h>
  18 #include <linux/fs.h>
  19 #include <linux/jbd2.h>
  20 #include <linux/errno.h>
  21 #include <linux/slab.h>
  22 #include <linux/blkdev.h>
  23 #include <trace/events/jbd2.h>
  24
  25 /*
  26  * Unlink a buffer from a transaction checkpoint list.
  27  *
  28  * Called with j_list_lock held.
  29  */
  30 static inline void __buffer_unlink_first(struct journal_head *jh)
  31 {
  32         transaction_t *transaction = jh->b_cp_transaction;
  33
  34         jh->b_cpnext->b_cpprev = jh->b_cpprev;
  35         jh->b_cpprev->b_cpnext = jh->b_cpnext;
  36         if (transaction->t_checkpoint_list == jh) {
  37                 transaction->t_checkpoint_list = jh->b_cpnext;
  38                 if (transaction->t_checkpoint_list == jh)
  39                         transaction->t_checkpoint_list = NULL;
  40         }
  41 }
  42
  43 /*
  44  * Unlink a buffer from a transaction checkpoint(io) list.
  45  *
  46  * Called with j_list_lock held.
  47  */
  48 static inline void __buffer_unlink(struct journal_head *jh)
  49 {
  50         transaction_t *transaction = jh->b_cp_transaction;
  51
  52         __buffer_unlink_first(jh);
  53         if (transaction->t_checkpoint_io_list == jh) {
  54                 transaction->t_checkpoint_io_list = jh->b_cpnext;
  55                 if (transaction->t_checkpoint_io_list == jh)
  56                         transaction->t_checkpoint_io_list = NULL;
  57         }
  58 }
  59
  60 /*
  61  * Move a buffer from the checkpoint list to the checkpoint io list
  62  *
  63  * Called with j_list_lock held
  64  */
  65 static inline void __buffer_relink_io(struct journal_head *jh)
  66 {
  67         transaction_t *transaction = jh->b_cp_transaction;
  68
  69         __buffer_unlink_first(jh);
  70
  71         if (!transaction->t_checkpoint_io_list) {
  72                 jh->b_cpnext = jh->b_cpprev = jh;
  73         } else {
  74                 jh->b_cpnext = transaction->t_checkpoint_io_list;
  75                 jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
  76                 jh->b_cpprev->b_cpnext = jh;
  77                 jh->b_cpnext->b_cpprev = jh;
  78         }
  79         transaction->t_checkpoint_io_list = jh;
  80 }
  81
  82 /*
  83  * Try to release a checkpointed buffer from its transaction.
  84  * Returns 1 if we released it and 2 if we also released the
  85  * whole transaction.
  86  *
  87  * Requires j_list_lock
  88  */
  89 static int __try_to_free_cp_buf(struct journal_head *jh)
  90 {
  91         int ret = 0;
  92         struct buffer_head *bh = jh2bh(jh);
  93
  94         if (jh->b_transaction == NULL && !buffer_locked(bh) &&
  95             !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
  96                 JBUFFER_TRACE(jh, "remove from checkpoint list");
  97                 ret = __jbd2_journal_remove_checkpoint(jh) + 1;
  98         }
  99         return ret;
 100 }
 101
 102 /*
 103  * __jbd2_log_wait_for_space: wait until there is space in the journal.
 104  *
 105  * Called under j-state_lock *only*.  It will be unlocked if we have to wait
 106  * for a checkpoint to free up some space in the log.
 107  */
 108 void __jbd2_log_wait_for_space(journal_t *journal)
 109 {
 110         int nblocks, space_left;
 111         /* assert_spin_locked(&journal->j_state_lock); */
 112
 113         nblocks = jbd2_space_needed(journal);
 114         while (jbd2_log_space_left(journal) < nblocks) {
 115                 write_unlock(&journal->j_state_lock);
 116                 mutex_lock(&journal->j_checkpoint_mutex);
 117
 118                 /*
 119                  * Test again, another process may have checkpointed while we
 120                  * were waiting for the checkpoint lock. If there are no
 121                  * transactions ready to be checkpointed, try to recover
 122                  * journal space by calling cleanup_journal_tail(), and if
 123                  * that doesn't work, by waiting for the currently committing
 124                  * transaction to complete.  If there is absolutely no way
 125                  * to make progress, this is either a BUG or corrupted
 126                  * filesystem, so abort the journal and leave a stack
 127                  * trace for forensic evidence.
 128                  */
 129                 write_lock(&journal->j_state_lock);
 130                 if (journal->j_flags & JBD2_ABORT) {
 131                         mutex_unlock(&journal->j_checkpoint_mutex);
 132                         return;
 133                 }
 134                 spin_lock(&journal->j_list_lock);
 135                 nblocks = jbd2_space_needed(journal);
 136                 space_left = jbd2_log_space_left(journal);
 137                 if (space_left < nblocks) {
 138                         int chkpt = journal->j_checkpoint_transactions != NULL;
 139                         tid_t tid = 0;
 140
 141                         if (journal->j_committing_transaction)
 142                                 tid = journal->j_committing_transaction->t_tid;
 143                         spin_unlock(&journal->j_list_lock);
 144                         write_unlock(&journal->j_state_lock);
 145                         if (chkpt) {
 146                                 jbd2_log_do_checkpoint(journal);
 147                         } else if (jbd2_cleanup_journal_tail(journal) == 0) {
 148                                 /* We were able to recover space; yay! */
 149                                 ;
 150                         } else if (tid) {
 151                                 /*
 152                                  * jbd2_journal_commit_transaction() may want
 153                                  * to take the checkpoint_mutex if JBD2_FLUSHED
 154                                  * is set.  So we need to temporarily drop it.
 155                                  */
 156                                 mutex_unlock(&journal->j_checkpoint_mutex);
 157                                 jbd2_log_wait_commit(journal, tid);
 158                                 write_lock(&journal->j_state_lock);
 159                                 continue;
 160                         } else {
 161                                 printk(KERN_ERR "%s: needed %d blocks and "
 162                                        "only had %d space available\n",
 163                                        __func__, nblocks, space_left);
 164                                 printk(KERN_ERR "%s: no way to get more "
 165                                        "journal space in %s\n", __func__,
 166                                        journal->j_devname);
 167                                 WARN_ON(1);
 168                                 jbd2_journal_abort(journal, 0);
 169                         }
 170                         write_lock(&journal->j_state_lock);
 171                 } else {
 172                         spin_unlock(&journal->j_list_lock);
 173                 }
 174                 mutex_unlock(&journal->j_checkpoint_mutex);
 175         }
 176 }
 177
 178 static void
 179 __flush_batch(journal_t *journal, int *batch_count)
 180 {
 181         int i;
 182         struct blk_plug plug;
 183
 184         blk_start_plug(&plug);
 185         for (i = 0; i < *batch_count; i++)
 186                 write_dirty_buffer(journal->j_chkpt_bhs[i], REQ_SYNC);
 187         blk_finish_plug(&plug);
 188
 189         for (i = 0; i < *batch_count; i++) {
 190                 struct buffer_head *bh = journal->j_chkpt_bhs[i];
 191                 BUFFER_TRACE(bh, "brelse");
 192                 __brelse(bh);
 193         }
 194         *batch_count = 0;
 195 }
 196
 197 /*
 198  * Perform an actual checkpoint. We take the first transaction on the
 199  * list of transactions to be checkpointed and send all its buffers
 200  * to disk. We submit larger chunks of data at once.
 201  *
 202  * The journal should be locked before calling this function.
 203  * Called with j_checkpoint_mutex held.
 204  */
 205 int jbd2_log_do_checkpoint(journal_t *journal)
 206 {
 207         struct journal_head     *jh;
 208         struct buffer_head      *bh;
 209         transaction_t           *transaction;
 210         tid_t                   this_tid;
 211         int                     result, batch_count = 0;
 212
 213         jbd_debug(1, "Start checkpoint\n");
 214
 215         /*
 216          * First thing: if there are any transactions in the log which
 217          * don't need checkpointing, just eliminate them from the
 218          * journal straight away.
 219          */
 220         result = jbd2_cleanup_journal_tail(journal);
 221         trace_jbd2_checkpoint(journal, result);
 222         jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
 223         if (result <= 0)
 224                 return result;
 225
 226         /*
 227          * OK, we need to start writing disk blocks.  Take one transaction
 228          * and write it.
 229          */
 230         result = 0;
 231         spin_lock(&journal->j_list_lock);
 232         if (!journal->j_checkpoint_transactions)
 233                 goto out;
 234         transaction = journal->j_checkpoint_transactions;
 235         if (transaction->t_chp_stats.cs_chp_time == 0)
 236                 transaction->t_chp_stats.cs_chp_time = jiffies;
 237         this_tid = transaction->t_tid;
 238 restart:
 239         /*
 240          * If someone cleaned up this transaction while we slept, we're
 241          * done (maybe it's a new transaction, but it fell at the same
 242          * address).
 243          */
 244         if (journal->j_checkpoint_transactions != transaction ||
 245             transaction->t_tid != this_tid)
 246                 goto out;
 247
 248         /* checkpoint all of the transaction's buffers */
 249         while (transaction->t_checkpoint_list) {
 250                 jh = transaction->t_checkpoint_list;
 251                 bh = jh2bh(jh);
 252
 253                 if (buffer_locked(bh)) {
 254                         get_bh(bh);
 255                         spin_unlock(&journal->j_list_lock);
 256                         wait_on_buffer(bh);
 257                         /* the journal_head may have gone by now */
 258                         BUFFER_TRACE(bh, "brelse");
 259                         __brelse(bh);
 260                         goto retry;
 261                 }
 262                 if (jh->b_transaction != NULL) {
 263                         transaction_t *t = jh->b_transaction;
 264                         tid_t tid = t->t_tid;
 265
 266                         transaction->t_chp_stats.cs_forced_to_close++;
 267                         spin_unlock(&journal->j_list_lock);
 268                         if (unlikely(journal->j_flags & JBD2_UNMOUNT))
 269                                 /*
 270                                  * The journal thread is dead; so
 271                                  * starting and waiting for a commit
 272                                  * to finish will cause us to wait for
 273                                  * a _very_ long time.
 274                                  */
 275                                 printk(KERN_ERR
 276                 "JBD2: %s: Waiting for Godot: block %llu\n",
 277                 journal->j_devname, (unsigned long long) bh->b_blocknr);
 278
 279                         jbd2_log_start_commit(journal, tid);
 280                         jbd2_log_wait_commit(journal, tid);
 281                         goto retry;
 282                 }
 283                 if (!buffer_dirty(bh)) {
 284                         if (unlikely(buffer_write_io_error(bh)) && !result)
 285                                 result = -EIO;
 286                         BUFFER_TRACE(bh, "remove from checkpoint");
 287                         if (__jbd2_journal_remove_checkpoint(jh))
 288                                 /* The transaction was released; we're done */
 289                                 goto out;
 290                         continue;
 291                 }
 292                 /*
 293                  * Important: we are about to write the buffer, and
 294                  * possibly block, while still holding the journal
 295                  * lock.  We cannot afford to let the transaction
 296                  * logic start messing around with this buffer before
 297                  * we write it to disk, as that would break
 298                  * recoverability.
 299                  */
 300                 BUFFER_TRACE(bh, "queue");
 301                 get_bh(bh);
 302                 J_ASSERT_BH(bh, !buffer_jwrite(bh));
 303                 journal->j_chkpt_bhs[batch_count++] = bh;
 304                 __buffer_relink_io(jh);
 305                 transaction->t_chp_stats.cs_written++;
 306                 if ((batch_count == JBD2_NR_BATCH) ||
 307                     need_resched() ||
 308                     spin_needbreak(&journal->j_list_lock))
 309                         goto unlock_and_flush;
 310         }
 311
 312         if (batch_count) {
 313                 unlock_and_flush:
 314                         spin_unlock(&journal->j_list_lock);
 315                 retry:
 316                         if (batch_count)
 317                                 __flush_batch(journal, &batch_count);
 318                         spin_lock(&journal->j_list_lock);
 319                         goto restart;
 320         }
 321
 322         /*
 323          * Now we issued all of the transaction's buffers, let's deal
 324          * with the buffers that are out for I/O.
 325          */
 326 restart2:
 327         /* Did somebody clean up the transaction in the meanwhile? */
 328         if (journal->j_checkpoint_transactions != transaction ||
 329             transaction->t_tid != this_tid)
 330                 goto out;
 331
 332         while (transaction->t_checkpoint_io_list) {
 333                 jh = transaction->t_checkpoint_io_list;
 334                 bh = jh2bh(jh);
 335                 if (buffer_locked(bh)) {
 336                         get_bh(bh);
 337                         spin_unlock(&journal->j_list_lock);
 338                         wait_on_buffer(bh);
 339                         /* the journal_head may have gone by now */
 340                         BUFFER_TRACE(bh, "brelse");
 341                         __brelse(bh);
 342                         spin_lock(&journal->j_list_lock);
 343                         goto restart2;
 344                 }
 345                 if (unlikely(buffer_write_io_error(bh)) && !result)
 346                         result = -EIO;
 347
 348                 /*
 349                  * Now in whatever state the buffer currently is, we
 350                  * know that it has been written out and so we can
 351                  * drop it from the list
 352                  */
 353                 if (__jbd2_journal_remove_checkpoint(jh))
 354                         break;
 355         }
 356 out:
 357         spin_unlock(&journal->j_list_lock);
 358         if (result < 0)
 359                 jbd2_journal_abort(journal, result);
 360         else
 361                 result = jbd2_cleanup_journal_tail(journal);
 362
 363         return (result < 0) ? result : 0;
 364 }
 365
 366 /*
 367  * Check the list of checkpoint transactions for the journal to see if
 368  * we have already got rid of any since the last update of the log tail
 369  * in the journal superblock.  If so, we can instantly roll the
 370  * superblock forward to remove those transactions from the log.
 371  *
 372  * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
 373  *
 374  * Called with the journal lock held.
 375  *
 376  * This is the only part of the journaling code which really needs to be
 377  * aware of transaction aborts.  Checkpointing involves writing to the
 378  * main filesystem area rather than to the journal, so it can proceed
 379  * even in abort state, but we must not update the super block if
 380  * checkpointing may have failed.  Otherwise, we would lose some metadata
 381  * buffers which should be written-back to the filesystem.
 382  */
 383
 384 int jbd2_cleanup_journal_tail(journal_t *journal)
 385 {
 386         tid_t           first_tid;
 387         unsigned long   blocknr;
 388
 389         if (is_journal_aborted(journal))
 390                 return -EIO;
 391
 392         if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
 393                 return 1;
 394         J_ASSERT(blocknr != 0);
 395
 396         /*
 397          * We need to make sure that any blocks that were recently written out
 398          * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
 399          * we drop the transactions from the journal. It's unlikely this will
 400          * be necessary, especially with an appropriately sized journal, but we
 401          * need this to guarantee correctness.  Fortunately
 402          * jbd2_cleanup_journal_tail() doesn't get called all that often.
 403          */
 404         if (journal->j_flags & JBD2_BARRIER)
 405                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS, NULL);
 406
 407         return __jbd2_update_log_tail(journal, first_tid, blocknr);
 408 }
 409
 410
 411 /* Checkpoint list management */
 412
 413 /*
 414  * journal_clean_one_cp_list
 415  *
 416  * Find all the written-back checkpoint buffers in the given list and
 417  * release them. If 'destroy' is set, clean all buffers unconditionally.
 418  *
 419  * Called with j_list_lock held.
 420  * Returns 1 if we freed the transaction, 0 otherwise.
 421  */
 422 static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy)
 423 {
 424         struct journal_head *last_jh;
 425         struct journal_head *next_jh = jh;
 426         int ret;
 427
 428         if (!jh)
 429                 return 0;
 430
 431         last_jh = jh->b_cpprev;
 432         do {
 433                 jh = next_jh;
 434                 next_jh = jh->b_cpnext;
 435                 if (!destroy)
 436                         ret = __try_to_free_cp_buf(jh);
 437                 else
 438                         ret = __jbd2_journal_remove_checkpoint(jh) + 1;
 439                 if (!ret)
 440                         return 0;
 441                 if (ret == 2)
 442                         return 1;
 443                 /*
 444                  * This function only frees up some memory
 445                  * if possible so we dont have an obligation
 446                  * to finish processing. Bail out if preemption
 447                  * requested:
 448                  */
 449                 if (need_resched())
 450                         return 0;
 451         } while (jh != last_jh);
 452
 453         return 0;
 454 }
 455
 456 /*
 457  * journal_clean_checkpoint_list
 458  *
 459  * Find all the written-back checkpoint buffers in the journal and release them.
 460  * If 'destroy' is set, release all buffers unconditionally.
 461  *
 462  * Called with j_list_lock held.
 463  */
 464 void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
 465 {
 466         transaction_t *transaction, *last_transaction, *next_transaction;
 467         int ret;
 468
 469         transaction = journal->j_checkpoint_transactions;
 470         if (!transaction)
 471                 return;
 472
 473         last_transaction = transaction->t_cpprev;
 474         next_transaction = transaction;
 475         do {
 476                 transaction = next_transaction;
 477                 next_transaction = transaction->t_cpnext;
 478                 ret = journal_clean_one_cp_list(transaction->t_checkpoint_list,
 479                                                 destroy);
 480                 /*
 481                  * This function only frees up some memory if possible so we
 482                  * dont have an obligation to finish processing. Bail out if
 483                  * preemption requested:
 484                  */
 485                 if (need_resched())
 486                         return;
 487                 if (ret)
 488                         continue;
 489                 /*
 490                  * It is essential that we are as careful as in the case of
 491                  * t_checkpoint_list with removing the buffer from the list as
 492                  * we can possibly see not yet submitted buffers on io_list
 493                  */
 494                 ret = journal_clean_one_cp_list(transaction->
 495                                 t_checkpoint_io_list, destroy);
 496                 if (need_resched())
 497                         return;
 498                 /*
 499                  * Stop scanning if we couldn't free the transaction. This
 500                  * avoids pointless scanning of transactions which still
 501                  * weren't checkpointed.
 502                  */
 503                 if (!ret)
 504                         return;
 505         } while (transaction != last_transaction);
 506 }
 507
 508 /*
 509  * Remove buffers from all checkpoint lists as journal is aborted and we just
 510  * need to free memory
 511  */
 512 void jbd2_journal_destroy_checkpoint(journal_t *journal)
 513 {
 514         /*
 515          * We loop because __jbd2_journal_clean_checkpoint_list() may abort
 516          * early due to a need of rescheduling.
 517          */
 518         while (1) {
 519                 spin_lock(&journal->j_list_lock);
 520                 if (!journal->j_checkpoint_transactions) {
 521                         spin_unlock(&journal->j_list_lock);
 522                         break;
 523                 }
 524                 __jbd2_journal_clean_checkpoint_list(journal, true);
 525                 spin_unlock(&journal->j_list_lock);
 526                 cond_resched();
 527         }
 528 }
 529
 530 /*
 531  * journal_remove_checkpoint: called after a buffer has been committed
 532  * to disk (either by being write-back flushed to disk, or being
 533  * committed to the log).
 534  *
 535  * We cannot safely clean a transaction out of the log until all of the
 536  * buffer updates committed in that transaction have safely been stored
 537  * elsewhere on disk.  To achieve this, all of the buffers in a
 538  * transaction need to be maintained on the transaction's checkpoint
 539  * lists until they have been rewritten, at which point this function is
 540  * called to remove the buffer from the existing transaction's
 541  * checkpoint lists.
 542  *
 543  * The function returns 1 if it frees the transaction, 0 otherwise.
 544  * The function can free jh and bh.
 545  *
 546  * This function is called with j_list_lock held.
 547  */
 548 int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
 549 {
 550         struct transaction_chp_stats_s *stats;
 551         transaction_t *transaction;
 552         journal_t *journal;
 553         int ret = 0;
 554
 555         JBUFFER_TRACE(jh, "entry");
 556
 557         if ((transaction = jh->b_cp_transaction) == NULL) {
 558                 JBUFFER_TRACE(jh, "not on transaction");
 559                 goto out;
 560         }
 561         journal = transaction->t_journal;
 562
 563         JBUFFER_TRACE(jh, "removing from transaction");
 564         __buffer_unlink(jh);
 565         jh->b_cp_transaction = NULL;
 566         jbd2_journal_put_journal_head(jh);
 567
 568         if (transaction->t_checkpoint_list != NULL ||
 569             transaction->t_checkpoint_io_list != NULL)
 570                 goto out;
 571
 572         /*
 573          * There is one special case to worry about: if we have just pulled the
 574          * buffer off a running or committing transaction's checkpoing list,
 575          * then even if the checkpoint list is empty, the transaction obviously
 576          * cannot be dropped!
 577          *
 578          * The locking here around t_state is a bit sleazy.
 579          * See the comment at the end of jbd2_journal_commit_transaction().
 580          */
 581         if (transaction->t_state != T_FINISHED)
 582                 goto out;
 583
 584         /* OK, that was the last buffer for the transaction: we can now
 585            safely remove this transaction from the log */
 586         stats = &transaction->t_chp_stats;
 587         if (stats->cs_chp_time)
 588                 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
 589                                                     jiffies);
 590         trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
 591                                     transaction->t_tid, stats);
 592
 593         __jbd2_journal_drop_transaction(journal, transaction);
 594         jbd2_journal_free_transaction(transaction);
 595         ret = 1;
 596 out:
 597         return ret;
 598 }
 599
 600 /*
 601  * journal_insert_checkpoint: put a committed buffer onto a checkpoint
 602  * list so that we know when it is safe to clean the transaction out of
 603  * the log.
 604  *
 605  * Called with the journal locked.
 606  * Called with j_list_lock held.
 607  */
 608 void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
 609                                transaction_t *transaction)
 610 {
 611         JBUFFER_TRACE(jh, "entry");
 612         J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
 613         J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
 614
 615         /* Get reference for checkpointing transaction */
 616         jbd2_journal_grab_journal_head(jh2bh(jh));
 617         jh->b_cp_transaction = transaction;
 618
 619         if (!transaction->t_checkpoint_list) {
 620                 jh->b_cpnext = jh->b_cpprev = jh;
 621         } else {
 622                 jh->b_cpnext = transaction->t_checkpoint_list;
 623                 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
 624                 jh->b_cpprev->b_cpnext = jh;
 625                 jh->b_cpnext->b_cpprev = jh;
 626         }
 627         transaction->t_checkpoint_list = jh;
 628 }
 629
 630 /*
 631  * We've finished with this transaction structure: adios...
 632  *
 633  * The transaction must have no links except for the checkpoint by this
 634  * point.
 635  *
 636  * Called with the journal locked.
 637  * Called with j_list_lock held.
 638  */
 639
 640 void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
 641 {
 642         assert_spin_locked(&journal->j_list_lock);
 643         if (transaction->t_cpnext) {
 644                 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
 645                 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
 646                 if (journal->j_checkpoint_transactions == transaction)
 647                         journal->j_checkpoint_transactions =
 648                                 transaction->t_cpnext;
 649                 if (journal->j_checkpoint_transactions == transaction)
 650                         journal->j_checkpoint_transactions = NULL;
 651         }
 652
 653         J_ASSERT(transaction->t_state == T_FINISHED);
 654         J_ASSERT(transaction->t_buffers == NULL);
 655         J_ASSERT(transaction->t_forget == NULL);
 656         J_ASSERT(transaction->t_shadow_list == NULL);
 657         J_ASSERT(transaction->t_checkpoint_list == NULL);
 658         J_ASSERT(transaction->t_checkpoint_io_list == NULL);
 659         J_ASSERT(atomic_read(&transaction->t_updates) == 0);
 660         J_ASSERT(journal->j_committing_transaction != transaction);
 661         J_ASSERT(journal->j_running_transaction != transaction);
 662
 663         trace_jbd2_drop_transaction(journal, transaction);
 664
 665         jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
 666 }