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 __acquires(&journal->j_state_lock)
 110 __releases(&journal->j_state_lock)
 111 {
 112         int nblocks, space_left;
 113         /* assert_spin_locked(&journal->j_state_lock); */
 114
 115         nblocks = journal->j_max_transaction_buffers;
 116         while (jbd2_log_space_left(journal) < nblocks) {
 117                 write_unlock(&journal->j_state_lock);
 118                 mutex_lock_io(&journal->j_checkpoint_mutex);
 119
 120                 /*
 121                  * Test again, another process may have checkpointed while we
 122                  * were waiting for the checkpoint lock. If there are no
 123                  * transactions ready to be checkpointed, try to recover
 124                  * journal space by calling cleanup_journal_tail(), and if
 125                  * that doesn't work, by waiting for the currently committing
 126                  * transaction to complete.  If there is absolutely no way
 127                  * to make progress, this is either a BUG or corrupted
 128                  * filesystem, so abort the journal and leave a stack
 129                  * trace for forensic evidence.
 130                  */
 131                 write_lock(&journal->j_state_lock);
 132                 if (journal->j_flags & JBD2_ABORT) {
 133                         mutex_unlock(&journal->j_checkpoint_mutex);
 134                         return;
 135                 }
 136                 spin_lock(&journal->j_list_lock);
 137                 space_left = jbd2_log_space_left(journal);
 138                 if (space_left < nblocks) {
 139                         int chkpt = journal->j_checkpoint_transactions != NULL;
 140                         tid_t tid = 0;
 141
 142                         if (journal->j_committing_transaction)
 143                                 tid = journal->j_committing_transaction->t_tid;
 144                         spin_unlock(&journal->j_list_lock);
 145                         write_unlock(&journal->j_state_lock);
 146                         if (chkpt) {
 147                                 jbd2_log_do_checkpoint(journal);
 148                         } else if (jbd2_cleanup_journal_tail(journal) == 0) {
 149                                 /* We were able to recover space; yay! */
 150                                 ;
 151                         } else if (tid) {
 152                                 /*
 153                                  * jbd2_journal_commit_transaction() may want
 154                                  * to take the checkpoint_mutex if JBD2_FLUSHED
 155                                  * is set.  So we need to temporarily drop it.
 156                                  */
 157                                 mutex_unlock(&journal->j_checkpoint_mutex);
 158                                 jbd2_log_wait_commit(journal, tid);
 159                                 write_lock(&journal->j_state_lock);
 160                                 continue;
 161                         } else {
 162                                 printk(KERN_ERR "%s: needed %d blocks and "
 163                                        "only had %d space available\n",
 164                                        __func__, nblocks, space_left);
 165                                 printk(KERN_ERR "%s: no way to get more "
 166                                        "journal space in %s\n", __func__,
 167                                        journal->j_devname);
 168                                 WARN_ON(1);
 169                                 jbd2_journal_abort(journal, -EIO);
 170                         }
 171                         write_lock(&journal->j_state_lock);
 172                 } else {
 173                         spin_unlock(&journal->j_list_lock);
 174                 }
 175                 mutex_unlock(&journal->j_checkpoint_mutex);
 176         }
 177 }
 178
 179 static void
 180 __flush_batch(journal_t *journal, int *batch_count)
 181 {
 182         int i;
 183         struct blk_plug plug;
 184
 185         blk_start_plug(&plug);
 186         for (i = 0; i < *batch_count; i++)
 187                 write_dirty_buffer(journal->j_chkpt_bhs[i], REQ_SYNC);
 188         blk_finish_plug(&plug);
 189
 190         for (i = 0; i < *batch_count; i++) {
 191                 struct buffer_head *bh = journal->j_chkpt_bhs[i];
 192                 BUFFER_TRACE(bh, "brelse");
 193                 __brelse(bh);
 194         }
 195         *batch_count = 0;
 196 }
 197
 198 /*
 199  * Perform an actual checkpoint. We take the first transaction on the
 200  * list of transactions to be checkpointed and send all its buffers
 201  * to disk. We submit larger chunks of data at once.
 202  *
 203  * The journal should be locked before calling this function.
 204  * Called with j_checkpoint_mutex held.
 205  */
 206 int jbd2_log_do_checkpoint(journal_t *journal)
 207 {
 208         struct journal_head     *jh;
 209         struct buffer_head      *bh;
 210         transaction_t           *transaction;
 211         tid_t                   this_tid;
 212         int                     result, batch_count = 0;
 213
 214         jbd_debug(1, "Start checkpoint\n");
 215
 216         /*
 217          * First thing: if there are any transactions in the log which
 218          * don't need checkpointing, just eliminate them from the
 219          * journal straight away.
 220          */
 221         result = jbd2_cleanup_journal_tail(journal);
 222         trace_jbd2_checkpoint(journal, result);
 223         jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
 224         if (result <= 0)
 225                 return result;
 226
 227         /*
 228          * OK, we need to start writing disk blocks.  Take one transaction
 229          * and write it.
 230          */
 231         result = 0;
 232         spin_lock(&journal->j_list_lock);
 233         if (!journal->j_checkpoint_transactions)
 234                 goto out;
 235         transaction = journal->j_checkpoint_transactions;
 236         if (transaction->t_chp_stats.cs_chp_time == 0)
 237                 transaction->t_chp_stats.cs_chp_time = jiffies;
 238         this_tid = transaction->t_tid;
 239 restart:
 240         /*
 241          * If someone cleaned up this transaction while we slept, we're
 242          * done (maybe it's a new transaction, but it fell at the same
 243          * address).
 244          */
 245         if (journal->j_checkpoint_transactions != transaction ||
 246             transaction->t_tid != this_tid)
 247                 goto out;
 248
 249         /* checkpoint all of the transaction's buffers */
 250         while (transaction->t_checkpoint_list) {
 251                 jh = transaction->t_checkpoint_list;
 252                 bh = jh2bh(jh);
 253
 254                 if (buffer_locked(bh)) {
 255                         get_bh(bh);
 256                         spin_unlock(&journal->j_list_lock);
 257                         wait_on_buffer(bh);
 258                         /* the journal_head may have gone by now */
 259                         BUFFER_TRACE(bh, "brelse");
 260                         __brelse(bh);
 261                         goto retry;
 262                 }
 263                 if (jh->b_transaction != NULL) {
 264                         transaction_t *t = jh->b_transaction;
 265                         tid_t tid = t->t_tid;
 266
 267                         transaction->t_chp_stats.cs_forced_to_close++;
 268                         spin_unlock(&journal->j_list_lock);
 269                         if (unlikely(journal->j_flags & JBD2_UNMOUNT))
 270                                 /*
 271                                  * The journal thread is dead; so
 272                                  * starting and waiting for a commit
 273                                  * to finish will cause us to wait for
 274                                  * a _very_ long time.
 275                                  */
 276                                 printk(KERN_ERR
 277                 "JBD2: %s: Waiting for Godot: block %llu\n",
 278                 journal->j_devname, (unsigned long long) bh->b_blocknr);
 279
 280                         if (batch_count)
 281                                 __flush_batch(journal, &batch_count);
 282                         jbd2_log_start_commit(journal, tid);
 283                         /*
 284                          * jbd2_journal_commit_transaction() may want
 285                          * to take the checkpoint_mutex if JBD2_FLUSHED
 286                          * is set, jbd2_update_log_tail() called by
 287                          * jbd2_journal_commit_transaction() may also take
 288                          * checkpoint_mutex.  So we need to temporarily
 289                          * drop it.
 290                          */
 291                         mutex_unlock(&journal->j_checkpoint_mutex);
 292                         jbd2_log_wait_commit(journal, tid);
 293                         mutex_lock_io(&journal->j_checkpoint_mutex);
 294                         spin_lock(&journal->j_list_lock);
 295                         goto restart;
 296                 }
 297                 if (!buffer_dirty(bh)) {
 298                         if (unlikely(buffer_write_io_error(bh)) && !result)
 299                                 result = -EIO;
 300                         BUFFER_TRACE(bh, "remove from checkpoint");
 301                         if (__jbd2_journal_remove_checkpoint(jh))
 302                                 /* The transaction was released; we're done */
 303                                 goto out;
 304                         continue;
 305                 }
 306                 /*
 307                  * Important: we are about to write the buffer, and
 308                  * possibly block, while still holding the journal
 309                  * lock.  We cannot afford to let the transaction
 310                  * logic start messing around with this buffer before
 311                  * we write it to disk, as that would break
 312                  * recoverability.
 313                  */
 314                 BUFFER_TRACE(bh, "queue");
 315                 get_bh(bh);
 316                 J_ASSERT_BH(bh, !buffer_jwrite(bh));
 317                 journal->j_chkpt_bhs[batch_count++] = bh;
 318                 __buffer_relink_io(jh);
 319                 transaction->t_chp_stats.cs_written++;
 320                 if ((batch_count == JBD2_NR_BATCH) ||
 321                     need_resched() ||
 322                     spin_needbreak(&journal->j_list_lock))
 323                         goto unlock_and_flush;
 324         }
 325
 326         if (batch_count) {
 327                 unlock_and_flush:
 328                         spin_unlock(&journal->j_list_lock);
 329                 retry:
 330                         if (batch_count)
 331                                 __flush_batch(journal, &batch_count);
 332                         spin_lock(&journal->j_list_lock);
 333                         goto restart;
 334         }
 335
 336         /*
 337          * Now we issued all of the transaction's buffers, let's deal
 338          * with the buffers that are out for I/O.
 339          */
 340 restart2:
 341         /* Did somebody clean up the transaction in the meanwhile? */
 342         if (journal->j_checkpoint_transactions != transaction ||
 343             transaction->t_tid != this_tid)
 344                 goto out;
 345
 346         while (transaction->t_checkpoint_io_list) {
 347                 jh = transaction->t_checkpoint_io_list;
 348                 bh = jh2bh(jh);
 349                 if (buffer_locked(bh)) {
 350                         get_bh(bh);
 351                         spin_unlock(&journal->j_list_lock);
 352                         wait_on_buffer(bh);
 353                         /* the journal_head may have gone by now */
 354                         BUFFER_TRACE(bh, "brelse");
 355                         __brelse(bh);
 356                         spin_lock(&journal->j_list_lock);
 357                         goto restart2;
 358                 }
 359                 if (unlikely(buffer_write_io_error(bh)) && !result)
 360                         result = -EIO;
 361
 362                 /*
 363                  * Now in whatever state the buffer currently is, we
 364                  * know that it has been written out and so we can
 365                  * drop it from the list
 366                  */
 367                 if (__jbd2_journal_remove_checkpoint(jh))
 368                         break;
 369         }
 370 out:
 371         spin_unlock(&journal->j_list_lock);
 372         if (result < 0)
 373                 jbd2_journal_abort(journal, result);
 374         else
 375                 result = jbd2_cleanup_journal_tail(journal);
 376
 377         return (result < 0) ? result : 0;
 378 }
 379
 380 /*
 381  * Check the list of checkpoint transactions for the journal to see if
 382  * we have already got rid of any since the last update of the log tail
 383  * in the journal superblock.  If so, we can instantly roll the
 384  * superblock forward to remove those transactions from the log.
 385  *
 386  * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
 387  *
 388  * Called with the journal lock held.
 389  *
 390  * This is the only part of the journaling code which really needs to be
 391  * aware of transaction aborts.  Checkpointing involves writing to the
 392  * main filesystem area rather than to the journal, so it can proceed
 393  * even in abort state, but we must not update the super block if
 394  * checkpointing may have failed.  Otherwise, we would lose some metadata
 395  * buffers which should be written-back to the filesystem.
 396  */
 397
 398 int jbd2_cleanup_journal_tail(journal_t *journal)
 399 {
 400         tid_t           first_tid;
 401         unsigned long   blocknr;
 402
 403         if (is_journal_aborted(journal))
 404                 return -EIO;
 405
 406         if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
 407                 return 1;
 408         J_ASSERT(blocknr != 0);
 409
 410         /*
 411          * We need to make sure that any blocks that were recently written out
 412          * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
 413          * we drop the transactions from the journal. It's unlikely this will
 414          * be necessary, especially with an appropriately sized journal, but we
 415          * need this to guarantee correctness.  Fortunately
 416          * jbd2_cleanup_journal_tail() doesn't get called all that often.
 417          */
 418         if (journal->j_flags & JBD2_BARRIER)
 419                 blkdev_issue_flush(journal->j_fs_dev, GFP_NOFS);
 420
 421         return __jbd2_update_log_tail(journal, first_tid, blocknr);
 422 }
 423
 424
 425 /* Checkpoint list management */
 426
 427 /*
 428  * journal_clean_one_cp_list
 429  *
 430  * Find all the written-back checkpoint buffers in the given list and
 431  * release them. If 'destroy' is set, clean all buffers unconditionally.
 432  *
 433  * Called with j_list_lock held.
 434  * Returns 1 if we freed the transaction, 0 otherwise.
 435  */
 436 static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy)
 437 {
 438         struct journal_head *last_jh;
 439         struct journal_head *next_jh = jh;
 440         int ret;
 441
 442         if (!jh)
 443                 return 0;
 444
 445         last_jh = jh->b_cpprev;
 446         do {
 447                 jh = next_jh;
 448                 next_jh = jh->b_cpnext;
 449                 if (!destroy)
 450                         ret = __try_to_free_cp_buf(jh);
 451                 else
 452                         ret = __jbd2_journal_remove_checkpoint(jh) + 1;
 453                 if (!ret)
 454                         return 0;
 455                 if (ret == 2)
 456                         return 1;
 457                 /*
 458                  * This function only frees up some memory
 459                  * if possible so we dont have an obligation
 460                  * to finish processing. Bail out if preemption
 461                  * requested:
 462                  */
 463                 if (need_resched())
 464                         return 0;
 465         } while (jh != last_jh);
 466
 467         return 0;
 468 }
 469
 470 /*
 471  * journal_clean_checkpoint_list
 472  *
 473  * Find all the written-back checkpoint buffers in the journal and release them.
 474  * If 'destroy' is set, release all buffers unconditionally.
 475  *
 476  * Called with j_list_lock held.
 477  */
 478 void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
 479 {
 480         transaction_t *transaction, *last_transaction, *next_transaction;
 481         int ret;
 482
 483         transaction = journal->j_checkpoint_transactions;
 484         if (!transaction)
 485                 return;
 486
 487         last_transaction = transaction->t_cpprev;
 488         next_transaction = transaction;
 489         do {
 490                 transaction = next_transaction;
 491                 next_transaction = transaction->t_cpnext;
 492                 ret = journal_clean_one_cp_list(transaction->t_checkpoint_list,
 493                                                 destroy);
 494                 /*
 495                  * This function only frees up some memory if possible so we
 496                  * dont have an obligation to finish processing. Bail out if
 497                  * preemption requested:
 498                  */
 499                 if (need_resched())
 500                         return;
 501                 if (ret)
 502                         continue;
 503                 /*
 504                  * It is essential that we are as careful as in the case of
 505                  * t_checkpoint_list with removing the buffer from the list as
 506                  * we can possibly see not yet submitted buffers on io_list
 507                  */
 508                 ret = journal_clean_one_cp_list(transaction->
 509                                 t_checkpoint_io_list, destroy);
 510                 if (need_resched())
 511                         return;
 512                 /*
 513                  * Stop scanning if we couldn't free the transaction. This
 514                  * avoids pointless scanning of transactions which still
 515                  * weren't checkpointed.
 516                  */
 517                 if (!ret)
 518                         return;
 519         } while (transaction != last_transaction);
 520 }
 521
 522 /*
 523  * Remove buffers from all checkpoint lists as journal is aborted and we just
 524  * need to free memory
 525  */
 526 void jbd2_journal_destroy_checkpoint(journal_t *journal)
 527 {
 528         /*
 529          * We loop because __jbd2_journal_clean_checkpoint_list() may abort
 530          * early due to a need of rescheduling.
 531          */
 532         while (1) {
 533                 spin_lock(&journal->j_list_lock);
 534                 if (!journal->j_checkpoint_transactions) {
 535                         spin_unlock(&journal->j_list_lock);
 536                         break;
 537                 }
 538                 __jbd2_journal_clean_checkpoint_list(journal, true);
 539                 spin_unlock(&journal->j_list_lock);
 540                 cond_resched();
 541         }
 542 }
 543
 544 /*
 545  * journal_remove_checkpoint: called after a buffer has been committed
 546  * to disk (either by being write-back flushed to disk, or being
 547  * committed to the log).
 548  *
 549  * We cannot safely clean a transaction out of the log until all of the
 550  * buffer updates committed in that transaction have safely been stored
 551  * elsewhere on disk.  To achieve this, all of the buffers in a
 552  * transaction need to be maintained on the transaction's checkpoint
 553  * lists until they have been rewritten, at which point this function is
 554  * called to remove the buffer from the existing transaction's
 555  * checkpoint lists.
 556  *
 557  * The function returns 1 if it frees the transaction, 0 otherwise.
 558  * The function can free jh and bh.
 559  *
 560  * This function is called with j_list_lock held.
 561  */
 562 int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
 563 {
 564         struct transaction_chp_stats_s *stats;
 565         transaction_t *transaction;
 566         journal_t *journal;
 567         int ret = 0;
 568
 569         JBUFFER_TRACE(jh, "entry");
 570
 571         if ((transaction = jh->b_cp_transaction) == NULL) {
 572                 JBUFFER_TRACE(jh, "not on transaction");
 573                 goto out;
 574         }
 575         journal = transaction->t_journal;
 576
 577         JBUFFER_TRACE(jh, "removing from transaction");
 578         __buffer_unlink(jh);
 579         jh->b_cp_transaction = NULL;
 580         jbd2_journal_put_journal_head(jh);
 581
 582         if (transaction->t_checkpoint_list != NULL ||
 583             transaction->t_checkpoint_io_list != NULL)
 584                 goto out;
 585
 586         /*
 587          * There is one special case to worry about: if we have just pulled the
 588          * buffer off a running or committing transaction's checkpoing list,
 589          * then even if the checkpoint list is empty, the transaction obviously
 590          * cannot be dropped!
 591          *
 592          * The locking here around t_state is a bit sleazy.
 593          * See the comment at the end of jbd2_journal_commit_transaction().
 594          */
 595         if (transaction->t_state != T_FINISHED)
 596                 goto out;
 597
 598         /* OK, that was the last buffer for the transaction: we can now
 599            safely remove this transaction from the log */
 600         stats = &transaction->t_chp_stats;
 601         if (stats->cs_chp_time)
 602                 stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
 603                                                     jiffies);
 604         trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
 605                                     transaction->t_tid, stats);
 606
 607         __jbd2_journal_drop_transaction(journal, transaction);
 608         jbd2_journal_free_transaction(transaction);
 609         ret = 1;
 610 out:
 611         return ret;
 612 }
 613
 614 /*
 615  * journal_insert_checkpoint: put a committed buffer onto a checkpoint
 616  * list so that we know when it is safe to clean the transaction out of
 617  * the log.
 618  *
 619  * Called with the journal locked.
 620  * Called with j_list_lock held.
 621  */
 622 void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
 623                                transaction_t *transaction)
 624 {
 625         JBUFFER_TRACE(jh, "entry");
 626         J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
 627         J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
 628
 629         /* Get reference for checkpointing transaction */
 630         jbd2_journal_grab_journal_head(jh2bh(jh));
 631         jh->b_cp_transaction = transaction;
 632
 633         if (!transaction->t_checkpoint_list) {
 634                 jh->b_cpnext = jh->b_cpprev = jh;
 635         } else {
 636                 jh->b_cpnext = transaction->t_checkpoint_list;
 637                 jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
 638                 jh->b_cpprev->b_cpnext = jh;
 639                 jh->b_cpnext->b_cpprev = jh;
 640         }
 641         transaction->t_checkpoint_list = jh;
 642 }
 643
 644 /*
 645  * We've finished with this transaction structure: adios...
 646  *
 647  * The transaction must have no links except for the checkpoint by this
 648  * point.
 649  *
 650  * Called with the journal locked.
 651  * Called with j_list_lock held.
 652  */
 653
 654 void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
 655 {
 656         assert_spin_locked(&journal->j_list_lock);
 657         if (transaction->t_cpnext) {
 658                 transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
 659                 transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
 660                 if (journal->j_checkpoint_transactions == transaction)
 661                         journal->j_checkpoint_transactions =
 662                                 transaction->t_cpnext;
 663                 if (journal->j_checkpoint_transactions == transaction)
 664                         journal->j_checkpoint_transactions = NULL;
 665         }
 666
 667         J_ASSERT(transaction->t_state == T_FINISHED);
 668         J_ASSERT(transaction->t_buffers == NULL);
 669         J_ASSERT(transaction->t_forget == NULL);
 670         J_ASSERT(transaction->t_shadow_list == NULL);
 671         J_ASSERT(transaction->t_checkpoint_list == NULL);
 672         J_ASSERT(transaction->t_checkpoint_io_list == NULL);
 673         J_ASSERT(atomic_read(&transaction->t_updates) == 0);
 674         J_ASSERT(journal->j_committing_transaction != transaction);
 675         J_ASSERT(journal->j_running_transaction != transaction);
 676
 677         trace_jbd2_drop_transaction(journal, transaction);
 678
 679         jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
 680 }