linux/fs/jbd2/checkpoint.c
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   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#include <linux/blkdev.h>
  26#include <trace/events/jbd2.h>
  27
  28/*
  29 * Unlink a buffer from a transaction checkpoint list.
  30 *
  31 * Called with j_list_lock held.
  32 */
  33static inline void __buffer_unlink_first(struct journal_head *jh)
  34{
  35        transaction_t *transaction = jh->b_cp_transaction;
  36
  37        jh->b_cpnext->b_cpprev = jh->b_cpprev;
  38        jh->b_cpprev->b_cpnext = jh->b_cpnext;
  39        if (transaction->t_checkpoint_list == jh) {
  40                transaction->t_checkpoint_list = jh->b_cpnext;
  41                if (transaction->t_checkpoint_list == jh)
  42                        transaction->t_checkpoint_list = NULL;
  43        }
  44}
  45
  46/*
  47 * Unlink a buffer from a transaction checkpoint(io) list.
  48 *
  49 * Called with j_list_lock held.
  50 */
  51static inline void __buffer_unlink(struct journal_head *jh)
  52{
  53        transaction_t *transaction = jh->b_cp_transaction;
  54
  55        __buffer_unlink_first(jh);
  56        if (transaction->t_checkpoint_io_list == jh) {
  57                transaction->t_checkpoint_io_list = jh->b_cpnext;
  58                if (transaction->t_checkpoint_io_list == jh)
  59                        transaction->t_checkpoint_io_list = NULL;
  60        }
  61}
  62
  63/*
  64 * Move a buffer from the checkpoint list to the checkpoint io list
  65 *
  66 * Called with j_list_lock held
  67 */
  68static inline void __buffer_relink_io(struct journal_head *jh)
  69{
  70        transaction_t *transaction = jh->b_cp_transaction;
  71
  72        __buffer_unlink_first(jh);
  73
  74        if (!transaction->t_checkpoint_io_list) {
  75                jh->b_cpnext = jh->b_cpprev = jh;
  76        } else {
  77                jh->b_cpnext = transaction->t_checkpoint_io_list;
  78                jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
  79                jh->b_cpprev->b_cpnext = jh;
  80                jh->b_cpnext->b_cpprev = jh;
  81        }
  82        transaction->t_checkpoint_io_list = jh;
  83}
  84
  85/*
  86 * Try to release a checkpointed buffer from its transaction.
  87 * Returns 1 if we released it and 2 if we also released the
  88 * whole transaction.
  89 *
  90 * Requires j_list_lock
  91 */
  92static int __try_to_free_cp_buf(struct journal_head *jh)
  93{
  94        int ret = 0;
  95        struct buffer_head *bh = jh2bh(jh);
  96
  97        if (jh->b_transaction == NULL && !buffer_locked(bh) &&
  98            !buffer_dirty(bh) && !buffer_write_io_error(bh)) {
  99                /*
 100                 * Get our reference so that bh cannot be freed before
 101                 * we unlock it
 102                 */
 103                get_bh(bh);
 104                JBUFFER_TRACE(jh, "remove from checkpoint list");
 105                ret = __jbd2_journal_remove_checkpoint(jh) + 1;
 106                BUFFER_TRACE(bh, "release");
 107                __brelse(bh);
 108        }
 109        return ret;
 110}
 111
 112/*
 113 * __jbd2_log_wait_for_space: wait until there is space in the journal.
 114 *
 115 * Called under j-state_lock *only*.  It will be unlocked if we have to wait
 116 * for a checkpoint to free up some space in the log.
 117 */
 118void __jbd2_log_wait_for_space(journal_t *journal)
 119{
 120        int nblocks, space_left;
 121        /* assert_spin_locked(&journal->j_state_lock); */
 122
 123        nblocks = jbd_space_needed(journal);
 124        while (__jbd2_log_space_left(journal) < nblocks) {
 125                if (journal->j_flags & JBD2_ABORT)
 126                        return;
 127                write_unlock(&journal->j_state_lock);
 128                mutex_lock(&journal->j_checkpoint_mutex);
 129
 130                /*
 131                 * Test again, another process may have checkpointed while we
 132                 * were waiting for the checkpoint lock. If there are no
 133                 * transactions ready to be checkpointed, try to recover
 134                 * journal space by calling cleanup_journal_tail(), and if
 135                 * that doesn't work, by waiting for the currently committing
 136                 * transaction to complete.  If there is absolutely no way
 137                 * to make progress, this is either a BUG or corrupted
 138                 * filesystem, so abort the journal and leave a stack
 139                 * trace for forensic evidence.
 140                 */
 141                write_lock(&journal->j_state_lock);
 142                spin_lock(&journal->j_list_lock);
 143                nblocks = jbd_space_needed(journal);
 144                space_left = __jbd2_log_space_left(journal);
 145                if (space_left < nblocks) {
 146                        int chkpt = journal->j_checkpoint_transactions != NULL;
 147                        tid_t tid = 0;
 148
 149                        if (journal->j_committing_transaction)
 150                                tid = journal->j_committing_transaction->t_tid;
 151                        spin_unlock(&journal->j_list_lock);
 152                        write_unlock(&journal->j_state_lock);
 153                        if (chkpt) {
 154                                jbd2_log_do_checkpoint(journal);
 155                        } else if (jbd2_cleanup_journal_tail(journal) == 0) {
 156                                /* We were able to recover space; yay! */
 157                                ;
 158                        } else if (tid) {
 159                                jbd2_log_wait_commit(journal, tid);
 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/*
 179 * Clean up transaction's list of buffers submitted for io.
 180 * We wait for any pending IO to complete and remove any clean
 181 * buffers. Note that we take the buffers in the opposite ordering
 182 * from the one in which they were submitted for IO.
 183 *
 184 * Return 0 on success, and return <0 if some buffers have failed
 185 * to be written out.
 186 *
 187 * Called with j_list_lock held.
 188 */
 189static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
 190{
 191        struct journal_head *jh;
 192        struct buffer_head *bh;
 193        tid_t this_tid;
 194        int released = 0;
 195        int ret = 0;
 196
 197        this_tid = transaction->t_tid;
 198restart:
 199        /* Did somebody clean up the transaction in the meanwhile? */
 200        if (journal->j_checkpoint_transactions != transaction ||
 201                        transaction->t_tid != this_tid)
 202                return ret;
 203        while (!released && transaction->t_checkpoint_io_list) {
 204                jh = transaction->t_checkpoint_io_list;
 205                bh = jh2bh(jh);
 206                get_bh(bh);
 207                if (buffer_locked(bh)) {
 208                        spin_unlock(&journal->j_list_lock);
 209                        wait_on_buffer(bh);
 210                        /* the journal_head may have gone by now */
 211                        BUFFER_TRACE(bh, "brelse");
 212                        __brelse(bh);
 213                        spin_lock(&journal->j_list_lock);
 214                        goto restart;
 215                }
 216                if (unlikely(buffer_write_io_error(bh)))
 217                        ret = -EIO;
 218
 219                /*
 220                 * Now in whatever state the buffer currently is, we know that
 221                 * it has been written out and so we can drop it from the list
 222                 */
 223                released = __jbd2_journal_remove_checkpoint(jh);
 224                __brelse(bh);
 225        }
 226
 227        return ret;
 228}
 229
 230static void
 231__flush_batch(journal_t *journal, int *batch_count)
 232{
 233        int i;
 234        struct blk_plug plug;
 235
 236        blk_start_plug(&plug);
 237        for (i = 0; i < *batch_count; i++)
 238                write_dirty_buffer(journal->j_chkpt_bhs[i], WRITE_SYNC);
 239        blk_finish_plug(&plug);
 240
 241        for (i = 0; i < *batch_count; i++) {
 242                struct buffer_head *bh = journal->j_chkpt_bhs[i];
 243                BUFFER_TRACE(bh, "brelse");
 244                __brelse(bh);
 245        }
 246        *batch_count = 0;
 247}
 248
 249/*
 250 * Try to flush one buffer from the checkpoint list to disk.
 251 *
 252 * Return 1 if something happened which requires us to abort the current
 253 * scan of the checkpoint list.  Return <0 if the buffer has failed to
 254 * be written out.
 255 *
 256 * Called with j_list_lock held and drops it if 1 is returned
 257 */
 258static int __process_buffer(journal_t *journal, struct journal_head *jh,
 259                            int *batch_count, transaction_t *transaction)
 260{
 261        struct buffer_head *bh = jh2bh(jh);
 262        int ret = 0;
 263
 264        if (buffer_locked(bh)) {
 265                get_bh(bh);
 266                spin_unlock(&journal->j_list_lock);
 267                wait_on_buffer(bh);
 268                /* the journal_head may have gone by now */
 269                BUFFER_TRACE(bh, "brelse");
 270                __brelse(bh);
 271                ret = 1;
 272        } else if (jh->b_transaction != NULL) {
 273                transaction_t *t = jh->b_transaction;
 274                tid_t tid = t->t_tid;
 275
 276                transaction->t_chp_stats.cs_forced_to_close++;
 277                spin_unlock(&journal->j_list_lock);
 278                if (unlikely(journal->j_flags & JBD2_UNMOUNT))
 279                        /*
 280                         * The journal thread is dead; so starting and
 281                         * waiting for a commit to finish will cause
 282                         * us to wait for a _very_ long time.
 283                         */
 284                        printk(KERN_ERR "JBD2: %s: "
 285                               "Waiting for Godot: block %llu\n",
 286                               journal->j_devname,
 287                               (unsigned long long) bh->b_blocknr);
 288                jbd2_log_start_commit(journal, tid);
 289                jbd2_log_wait_commit(journal, tid);
 290                ret = 1;
 291        } else if (!buffer_dirty(bh)) {
 292                ret = 1;
 293                if (unlikely(buffer_write_io_error(bh)))
 294                        ret = -EIO;
 295                get_bh(bh);
 296                BUFFER_TRACE(bh, "remove from checkpoint");
 297                __jbd2_journal_remove_checkpoint(jh);
 298                spin_unlock(&journal->j_list_lock);
 299                __brelse(bh);
 300        } else {
 301                /*
 302                 * Important: we are about to write the buffer, and
 303                 * possibly block, while still holding the journal lock.
 304                 * We cannot afford to let the transaction logic start
 305                 * messing around with this buffer before we write it to
 306                 * disk, as that would break recoverability.
 307                 */
 308                BUFFER_TRACE(bh, "queue");
 309                get_bh(bh);
 310                J_ASSERT_BH(bh, !buffer_jwrite(bh));
 311                journal->j_chkpt_bhs[*batch_count] = bh;
 312                __buffer_relink_io(jh);
 313                transaction->t_chp_stats.cs_written++;
 314                (*batch_count)++;
 315                if (*batch_count == JBD2_NR_BATCH) {
 316                        spin_unlock(&journal->j_list_lock);
 317                        __flush_batch(journal, batch_count);
 318                        ret = 1;
 319                }
 320        }
 321        return ret;
 322}
 323
 324/*
 325 * Perform an actual checkpoint. We take the first transaction on the
 326 * list of transactions to be checkpointed and send all its buffers
 327 * to disk. We submit larger chunks of data at once.
 328 *
 329 * The journal should be locked before calling this function.
 330 * Called with j_checkpoint_mutex held.
 331 */
 332int jbd2_log_do_checkpoint(journal_t *journal)
 333{
 334        transaction_t *transaction;
 335        tid_t this_tid;
 336        int result;
 337
 338        jbd_debug(1, "Start checkpoint\n");
 339
 340        /*
 341         * First thing: if there are any transactions in the log which
 342         * don't need checkpointing, just eliminate them from the
 343         * journal straight away.
 344         */
 345        result = jbd2_cleanup_journal_tail(journal);
 346        trace_jbd2_checkpoint(journal, result);
 347        jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
 348        if (result <= 0)
 349                return result;
 350
 351        /*
 352         * OK, we need to start writing disk blocks.  Take one transaction
 353         * and write it.
 354         */
 355        result = 0;
 356        spin_lock(&journal->j_list_lock);
 357        if (!journal->j_checkpoint_transactions)
 358                goto out;
 359        transaction = journal->j_checkpoint_transactions;
 360        if (transaction->t_chp_stats.cs_chp_time == 0)
 361                transaction->t_chp_stats.cs_chp_time = jiffies;
 362        this_tid = transaction->t_tid;
 363restart:
 364        /*
 365         * If someone cleaned up this transaction while we slept, we're
 366         * done (maybe it's a new transaction, but it fell at the same
 367         * address).
 368         */
 369        if (journal->j_checkpoint_transactions == transaction &&
 370                        transaction->t_tid == this_tid) {
 371                int batch_count = 0;
 372                struct journal_head *jh;
 373                int retry = 0, err;
 374
 375                while (!retry && transaction->t_checkpoint_list) {
 376                        jh = transaction->t_checkpoint_list;
 377                        retry = __process_buffer(journal, jh, &batch_count,
 378                                                 transaction);
 379                        if (retry < 0 && !result)
 380                                result = retry;
 381                        if (!retry && (need_resched() ||
 382                                spin_needbreak(&journal->j_list_lock))) {
 383                                spin_unlock(&journal->j_list_lock);
 384                                retry = 1;
 385                                break;
 386                        }
 387                }
 388
 389                if (batch_count) {
 390                        if (!retry) {
 391                                spin_unlock(&journal->j_list_lock);
 392                                retry = 1;
 393                        }
 394                        __flush_batch(journal, &batch_count);
 395                }
 396
 397                if (retry) {
 398                        spin_lock(&journal->j_list_lock);
 399                        goto restart;
 400                }
 401                /*
 402                 * Now we have cleaned up the first transaction's checkpoint
 403                 * list. Let's clean up the second one
 404                 */
 405                err = __wait_cp_io(journal, transaction);
 406                if (!result)
 407                        result = err;
 408        }
 409out:
 410        spin_unlock(&journal->j_list_lock);
 411        if (result < 0)
 412                jbd2_journal_abort(journal, result);
 413        else
 414                result = jbd2_cleanup_journal_tail(journal);
 415
 416        return (result < 0) ? result : 0;
 417}
 418
 419/*
 420 * Check the list of checkpoint transactions for the journal to see if
 421 * we have already got rid of any since the last update of the log tail
 422 * in the journal superblock.  If so, we can instantly roll the
 423 * superblock forward to remove those transactions from the log.
 424 *
 425 * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
 426 *
 427 * Called with the journal lock held.
 428 *
 429 * This is the only part of the journaling code which really needs to be
 430 * aware of transaction aborts.  Checkpointing involves writing to the
 431 * main filesystem area rather than to the journal, so it can proceed
 432 * even in abort state, but we must not update the super block if
 433 * checkpointing may have failed.  Otherwise, we would lose some metadata
 434 * buffers which should be written-back to the filesystem.
 435 */
 436
 437int jbd2_cleanup_journal_tail(journal_t *journal)
 438{
 439        tid_t           first_tid;
 440        unsigned long   blocknr;
 441
 442        if (is_journal_aborted(journal))
 443                return 1;
 444
 445        if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
 446                return 1;
 447        J_ASSERT(blocknr != 0);
 448
 449        /*
 450         * We need to make sure that any blocks that were recently written out
 451         * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
 452         * we drop the transactions from the journal. It's unlikely this will
 453         * be necessary, especially with an appropriately sized journal, but we
 454         * need this to guarantee correctness.  Fortunately
 455         * jbd2_cleanup_journal_tail() doesn't get called all that often.
 456         */
 457        if (journal->j_flags & JBD2_BARRIER)
 458                blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
 459
 460        __jbd2_update_log_tail(journal, first_tid, blocknr);
 461        return 0;
 462}
 463
 464
 465/* Checkpoint list management */
 466
 467/*
 468 * journal_clean_one_cp_list
 469 *
 470 * Find all the written-back checkpoint buffers in the given list and
 471 * release them.
 472 *
 473 * Called with the journal locked.
 474 * Called with j_list_lock held.
 475 * Returns number of buffers reaped (for debug)
 476 */
 477
 478static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
 479{
 480        struct journal_head *last_jh;
 481        struct journal_head *next_jh = jh;
 482        int ret, freed = 0;
 483
 484        *released = 0;
 485        if (!jh)
 486                return 0;
 487
 488        last_jh = jh->b_cpprev;
 489        do {
 490                jh = next_jh;
 491                next_jh = jh->b_cpnext;
 492                ret = __try_to_free_cp_buf(jh);
 493                if (ret) {
 494                        freed++;
 495                        if (ret == 2) {
 496                                *released = 1;
 497                                return freed;
 498                        }
 499                }
 500                /*
 501                 * This function only frees up some memory
 502                 * if possible so we dont have an obligation
 503                 * to finish processing. Bail out if preemption
 504                 * requested:
 505                 */
 506                if (need_resched())
 507                        return freed;
 508        } while (jh != last_jh);
 509
 510        return freed;
 511}
 512
 513/*
 514 * journal_clean_checkpoint_list
 515 *
 516 * Find all the written-back checkpoint buffers in the journal and release them.
 517 *
 518 * Called with the journal locked.
 519 * Called with j_list_lock held.
 520 * Returns number of buffers reaped (for debug)
 521 */
 522
 523int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
 524{
 525        transaction_t *transaction, *last_transaction, *next_transaction;
 526        int ret = 0;
 527        int released;
 528
 529        transaction = journal->j_checkpoint_transactions;
 530        if (!transaction)
 531                goto out;
 532
 533        last_transaction = transaction->t_cpprev;
 534        next_transaction = transaction;
 535        do {
 536                transaction = next_transaction;
 537                next_transaction = transaction->t_cpnext;
 538                ret += journal_clean_one_cp_list(transaction->
 539                                t_checkpoint_list, &released);
 540                /*
 541                 * This function only frees up some memory if possible so we
 542                 * dont have an obligation to finish processing. Bail out if
 543                 * preemption requested:
 544                 */
 545                if (need_resched())
 546                        goto out;
 547                if (released)
 548                        continue;
 549                /*
 550                 * It is essential that we are as careful as in the case of
 551                 * t_checkpoint_list with removing the buffer from the list as
 552                 * we can possibly see not yet submitted buffers on io_list
 553                 */
 554                ret += journal_clean_one_cp_list(transaction->
 555                                t_checkpoint_io_list, &released);
 556                if (need_resched())
 557                        goto out;
 558        } while (transaction != last_transaction);
 559out:
 560        return ret;
 561}
 562
 563/*
 564 * journal_remove_checkpoint: called after a buffer has been committed
 565 * to disk (either by being write-back flushed to disk, or being
 566 * committed to the log).
 567 *
 568 * We cannot safely clean a transaction out of the log until all of the
 569 * buffer updates committed in that transaction have safely been stored
 570 * elsewhere on disk.  To achieve this, all of the buffers in a
 571 * transaction need to be maintained on the transaction's checkpoint
 572 * lists until they have been rewritten, at which point this function is
 573 * called to remove the buffer from the existing transaction's
 574 * checkpoint lists.
 575 *
 576 * The function returns 1 if it frees the transaction, 0 otherwise.
 577 * The function can free jh and bh.
 578 *
 579 * This function is called with j_list_lock held.
 580 */
 581int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
 582{
 583        struct transaction_chp_stats_s *stats;
 584        transaction_t *transaction;
 585        journal_t *journal;
 586        int ret = 0;
 587
 588        JBUFFER_TRACE(jh, "entry");
 589
 590        if ((transaction = jh->b_cp_transaction) == NULL) {
 591                JBUFFER_TRACE(jh, "not on transaction");
 592                goto out;
 593        }
 594        journal = transaction->t_journal;
 595
 596        JBUFFER_TRACE(jh, "removing from transaction");
 597        __buffer_unlink(jh);
 598        jh->b_cp_transaction = NULL;
 599        jbd2_journal_put_journal_head(jh);
 600
 601        if (transaction->t_checkpoint_list != NULL ||
 602            transaction->t_checkpoint_io_list != NULL)
 603                goto out;
 604
 605        /*
 606         * There is one special case to worry about: if we have just pulled the
 607         * buffer off a running or committing transaction's checkpoing list,
 608         * then even if the checkpoint list is empty, the transaction obviously
 609         * cannot be dropped!
 610         *
 611         * The locking here around t_state is a bit sleazy.
 612         * See the comment at the end of jbd2_journal_commit_transaction().
 613         */
 614        if (transaction->t_state != T_FINISHED)
 615                goto out;
 616
 617        /* OK, that was the last buffer for the transaction: we can now
 618           safely remove this transaction from the log */
 619        stats = &transaction->t_chp_stats;
 620        if (stats->cs_chp_time)
 621                stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
 622                                                    jiffies);
 623        trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
 624                                    transaction->t_tid, stats);
 625
 626        __jbd2_journal_drop_transaction(journal, transaction);
 627        jbd2_journal_free_transaction(transaction);
 628
 629        /* Just in case anybody was waiting for more transactions to be
 630           checkpointed... */
 631        wake_up(&journal->j_wait_logspace);
 632        ret = 1;
 633out:
 634        return ret;
 635}
 636
 637/*
 638 * journal_insert_checkpoint: put a committed buffer onto a checkpoint
 639 * list so that we know when it is safe to clean the transaction out of
 640 * the log.
 641 *
 642 * Called with the journal locked.
 643 * Called with j_list_lock held.
 644 */
 645void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
 646                               transaction_t *transaction)
 647{
 648        JBUFFER_TRACE(jh, "entry");
 649        J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
 650        J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
 651
 652        /* Get reference for checkpointing transaction */
 653        jbd2_journal_grab_journal_head(jh2bh(jh));
 654        jh->b_cp_transaction = transaction;
 655
 656        if (!transaction->t_checkpoint_list) {
 657                jh->b_cpnext = jh->b_cpprev = jh;
 658        } else {
 659                jh->b_cpnext = transaction->t_checkpoint_list;
 660                jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
 661                jh->b_cpprev->b_cpnext = jh;
 662                jh->b_cpnext->b_cpprev = jh;
 663        }
 664        transaction->t_checkpoint_list = jh;
 665}
 666
 667/*
 668 * We've finished with this transaction structure: adios...
 669 *
 670 * The transaction must have no links except for the checkpoint by this
 671 * point.
 672 *
 673 * Called with the journal locked.
 674 * Called with j_list_lock held.
 675 */
 676
 677void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
 678{
 679        assert_spin_locked(&journal->j_list_lock);
 680        if (transaction->t_cpnext) {
 681                transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
 682                transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
 683                if (journal->j_checkpoint_transactions == transaction)
 684                        journal->j_checkpoint_transactions =
 685                                transaction->t_cpnext;
 686                if (journal->j_checkpoint_transactions == transaction)
 687                        journal->j_checkpoint_transactions = NULL;
 688        }
 689
 690        J_ASSERT(transaction->t_state == T_FINISHED);
 691        J_ASSERT(transaction->t_buffers == NULL);
 692        J_ASSERT(transaction->t_forget == NULL);
 693        J_ASSERT(transaction->t_iobuf_list == NULL);
 694        J_ASSERT(transaction->t_shadow_list == NULL);
 695        J_ASSERT(transaction->t_log_list == NULL);
 696        J_ASSERT(transaction->t_checkpoint_list == NULL);
 697        J_ASSERT(transaction->t_checkpoint_io_list == NULL);
 698        J_ASSERT(atomic_read(&transaction->t_updates) == 0);
 699        J_ASSERT(journal->j_committing_transaction != transaction);
 700        J_ASSERT(journal->j_running_transaction != transaction);
 701
 702        trace_jbd2_drop_transaction(journal, transaction);
 703
 704        jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
 705}
 706
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