linux/fs/jbd2/transaction.c
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   1/*
   2 * linux/fs/jbd2/transaction.c
   3 *
   4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
   5 *
   6 * Copyright 1998 Red Hat corp --- 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 * Generic filesystem transaction handling code; part of the ext2fs
  13 * journaling system.
  14 *
  15 * This file manages transactions (compound commits managed by the
  16 * journaling code) and handles (individual atomic operations by the
  17 * filesystem).
  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/timer.h>
  26#include <linux/mm.h>
  27#include <linux/highmem.h>
  28#include <linux/hrtimer.h>
  29#include <linux/backing-dev.h>
  30#include <linux/module.h>
  31
  32static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
  33
  34/*
  35 * jbd2_get_transaction: obtain a new transaction_t object.
  36 *
  37 * Simply allocate and initialise a new transaction.  Create it in
  38 * RUNNING state and add it to the current journal (which should not
  39 * have an existing running transaction: we only make a new transaction
  40 * once we have started to commit the old one).
  41 *
  42 * Preconditions:
  43 *      The journal MUST be locked.  We don't perform atomic mallocs on the
  44 *      new transaction and we can't block without protecting against other
  45 *      processes trying to touch the journal while it is in transition.
  46 *
  47 */
  48
  49static transaction_t *
  50jbd2_get_transaction(journal_t *journal, transaction_t *transaction)
  51{
  52        transaction->t_journal = journal;
  53        transaction->t_state = T_RUNNING;
  54        transaction->t_start_time = ktime_get();
  55        transaction->t_tid = journal->j_transaction_sequence++;
  56        transaction->t_expires = jiffies + journal->j_commit_interval;
  57        spin_lock_init(&transaction->t_handle_lock);
  58        atomic_set(&transaction->t_updates, 0);
  59        atomic_set(&transaction->t_outstanding_credits, 0);
  60        atomic_set(&transaction->t_handle_count, 0);
  61        INIT_LIST_HEAD(&transaction->t_inode_list);
  62        INIT_LIST_HEAD(&transaction->t_private_list);
  63
  64        /* Set up the commit timer for the new transaction. */
  65        journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires);
  66        add_timer(&journal->j_commit_timer);
  67
  68        J_ASSERT(journal->j_running_transaction == NULL);
  69        journal->j_running_transaction = transaction;
  70        transaction->t_max_wait = 0;
  71        transaction->t_start = jiffies;
  72
  73        return transaction;
  74}
  75
  76/*
  77 * Handle management.
  78 *
  79 * A handle_t is an object which represents a single atomic update to a
  80 * filesystem, and which tracks all of the modifications which form part
  81 * of that one update.
  82 */
  83
  84/*
  85 * Update transiaction's maximum wait time, if debugging is enabled.
  86 *
  87 * In order for t_max_wait to be reliable, it must be protected by a
  88 * lock.  But doing so will mean that start_this_handle() can not be
  89 * run in parallel on SMP systems, which limits our scalability.  So
  90 * unless debugging is enabled, we no longer update t_max_wait, which
  91 * means that maximum wait time reported by the jbd2_run_stats
  92 * tracepoint will always be zero.
  93 */
  94static inline void update_t_max_wait(transaction_t *transaction)
  95{
  96#ifdef CONFIG_JBD2_DEBUG
  97        unsigned long ts = jiffies;
  98
  99        if (jbd2_journal_enable_debug &&
 100            time_after(transaction->t_start, ts)) {
 101                ts = jbd2_time_diff(ts, transaction->t_start);
 102                spin_lock(&transaction->t_handle_lock);
 103                if (ts > transaction->t_max_wait)
 104                        transaction->t_max_wait = ts;
 105                spin_unlock(&transaction->t_handle_lock);
 106        }
 107#endif
 108}
 109
 110/*
 111 * start_this_handle: Given a handle, deal with any locking or stalling
 112 * needed to make sure that there is enough journal space for the handle
 113 * to begin.  Attach the handle to a transaction and set up the
 114 * transaction's buffer credits.
 115 */
 116
 117static int start_this_handle(journal_t *journal, handle_t *handle,
 118                             int gfp_mask)
 119{
 120        transaction_t   *transaction, *new_transaction = NULL;
 121        tid_t           tid;
 122        int             needed, need_to_start;
 123        int             nblocks = handle->h_buffer_credits;
 124
 125        if (nblocks > journal->j_max_transaction_buffers) {
 126                printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
 127                       current->comm, nblocks,
 128                       journal->j_max_transaction_buffers);
 129                return -ENOSPC;
 130        }
 131
 132alloc_transaction:
 133        if (!journal->j_running_transaction) {
 134                new_transaction = kzalloc(sizeof(*new_transaction), gfp_mask);
 135                if (!new_transaction) {
 136                        /*
 137                         * If __GFP_FS is not present, then we may be
 138                         * being called from inside the fs writeback
 139                         * layer, so we MUST NOT fail.  Since
 140                         * __GFP_NOFAIL is going away, we will arrange
 141                         * to retry the allocation ourselves.
 142                         */
 143                        if ((gfp_mask & __GFP_FS) == 0) {
 144                                congestion_wait(BLK_RW_ASYNC, HZ/50);
 145                                goto alloc_transaction;
 146                        }
 147                        return -ENOMEM;
 148                }
 149        }
 150
 151        jbd_debug(3, "New handle %p going live.\n", handle);
 152
 153        /*
 154         * We need to hold j_state_lock until t_updates has been incremented,
 155         * for proper journal barrier handling
 156         */
 157repeat:
 158        read_lock(&journal->j_state_lock);
 159        BUG_ON(journal->j_flags & JBD2_UNMOUNT);
 160        if (is_journal_aborted(journal) ||
 161            (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
 162                read_unlock(&journal->j_state_lock);
 163                kfree(new_transaction);
 164                return -EROFS;
 165        }
 166
 167        /* Wait on the journal's transaction barrier if necessary */
 168        if (journal->j_barrier_count) {
 169                read_unlock(&journal->j_state_lock);
 170                wait_event(journal->j_wait_transaction_locked,
 171                                journal->j_barrier_count == 0);
 172                goto repeat;
 173        }
 174
 175        if (!journal->j_running_transaction) {
 176                read_unlock(&journal->j_state_lock);
 177                if (!new_transaction)
 178                        goto alloc_transaction;
 179                write_lock(&journal->j_state_lock);
 180                if (!journal->j_running_transaction) {
 181                        jbd2_get_transaction(journal, new_transaction);
 182                        new_transaction = NULL;
 183                }
 184                write_unlock(&journal->j_state_lock);
 185                goto repeat;
 186        }
 187
 188        transaction = journal->j_running_transaction;
 189
 190        /*
 191         * If the current transaction is locked down for commit, wait for the
 192         * lock to be released.
 193         */
 194        if (transaction->t_state == T_LOCKED) {
 195                DEFINE_WAIT(wait);
 196
 197                prepare_to_wait(&journal->j_wait_transaction_locked,
 198                                        &wait, TASK_UNINTERRUPTIBLE);
 199                read_unlock(&journal->j_state_lock);
 200                schedule();
 201                finish_wait(&journal->j_wait_transaction_locked, &wait);
 202                goto repeat;
 203        }
 204
 205        /*
 206         * If there is not enough space left in the log to write all potential
 207         * buffers requested by this operation, we need to stall pending a log
 208         * checkpoint to free some more log space.
 209         */
 210        needed = atomic_add_return(nblocks,
 211                                   &transaction->t_outstanding_credits);
 212
 213        if (needed > journal->j_max_transaction_buffers) {
 214                /*
 215                 * If the current transaction is already too large, then start
 216                 * to commit it: we can then go back and attach this handle to
 217                 * a new transaction.
 218                 */
 219                DEFINE_WAIT(wait);
 220
 221                jbd_debug(2, "Handle %p starting new commit...\n", handle);
 222                atomic_sub(nblocks, &transaction->t_outstanding_credits);
 223                prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
 224                                TASK_UNINTERRUPTIBLE);
 225                tid = transaction->t_tid;
 226                need_to_start = !tid_geq(journal->j_commit_request, tid);
 227                read_unlock(&journal->j_state_lock);
 228                if (need_to_start)
 229                        jbd2_log_start_commit(journal, tid);
 230                schedule();
 231                finish_wait(&journal->j_wait_transaction_locked, &wait);
 232                goto repeat;
 233        }
 234
 235        /*
 236         * The commit code assumes that it can get enough log space
 237         * without forcing a checkpoint.  This is *critical* for
 238         * correctness: a checkpoint of a buffer which is also
 239         * associated with a committing transaction creates a deadlock,
 240         * so commit simply cannot force through checkpoints.
 241         *
 242         * We must therefore ensure the necessary space in the journal
 243         * *before* starting to dirty potentially checkpointed buffers
 244         * in the new transaction.
 245         *
 246         * The worst part is, any transaction currently committing can
 247         * reduce the free space arbitrarily.  Be careful to account for
 248         * those buffers when checkpointing.
 249         */
 250
 251        /*
 252         * @@@ AKPM: This seems rather over-defensive.  We're giving commit
 253         * a _lot_ of headroom: 1/4 of the journal plus the size of
 254         * the committing transaction.  Really, we only need to give it
 255         * committing_transaction->t_outstanding_credits plus "enough" for
 256         * the log control blocks.
 257         * Also, this test is inconsistent with the matching one in
 258         * jbd2_journal_extend().
 259         */
 260        if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) {
 261                jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
 262                atomic_sub(nblocks, &transaction->t_outstanding_credits);
 263                read_unlock(&journal->j_state_lock);
 264                write_lock(&journal->j_state_lock);
 265                if (__jbd2_log_space_left(journal) < jbd_space_needed(journal))
 266                        __jbd2_log_wait_for_space(journal);
 267                write_unlock(&journal->j_state_lock);
 268                goto repeat;
 269        }
 270
 271        /* OK, account for the buffers that this operation expects to
 272         * use and add the handle to the running transaction. 
 273         */
 274        update_t_max_wait(transaction);
 275        handle->h_transaction = transaction;
 276        atomic_inc(&transaction->t_updates);
 277        atomic_inc(&transaction->t_handle_count);
 278        jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
 279                  handle, nblocks,
 280                  atomic_read(&transaction->t_outstanding_credits),
 281                  __jbd2_log_space_left(journal));
 282        read_unlock(&journal->j_state_lock);
 283
 284        lock_map_acquire(&handle->h_lockdep_map);
 285        kfree(new_transaction);
 286        return 0;
 287}
 288
 289static struct lock_class_key jbd2_handle_key;
 290
 291/* Allocate a new handle.  This should probably be in a slab... */
 292static handle_t *new_handle(int nblocks)
 293{
 294        handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
 295        if (!handle)
 296                return NULL;
 297        memset(handle, 0, sizeof(*handle));
 298        handle->h_buffer_credits = nblocks;
 299        handle->h_ref = 1;
 300
 301        lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle",
 302                                                &jbd2_handle_key, 0);
 303
 304        return handle;
 305}
 306
 307/**
 308 * handle_t *jbd2_journal_start() - Obtain a new handle.
 309 * @journal: Journal to start transaction on.
 310 * @nblocks: number of block buffer we might modify
 311 *
 312 * We make sure that the transaction can guarantee at least nblocks of
 313 * modified buffers in the log.  We block until the log can guarantee
 314 * that much space.
 315 *
 316 * This function is visible to journal users (like ext3fs), so is not
 317 * called with the journal already locked.
 318 *
 319 * Return a pointer to a newly allocated handle, or NULL on failure
 320 */
 321handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int gfp_mask)
 322{
 323        handle_t *handle = journal_current_handle();
 324        int err;
 325
 326        if (!journal)
 327                return ERR_PTR(-EROFS);
 328
 329        if (handle) {
 330                J_ASSERT(handle->h_transaction->t_journal == journal);
 331                handle->h_ref++;
 332                return handle;
 333        }
 334
 335        handle = new_handle(nblocks);
 336        if (!handle)
 337                return ERR_PTR(-ENOMEM);
 338
 339        current->journal_info = handle;
 340
 341        err = start_this_handle(journal, handle, gfp_mask);
 342        if (err < 0) {
 343                jbd2_free_handle(handle);
 344                current->journal_info = NULL;
 345                handle = ERR_PTR(err);
 346        }
 347        return handle;
 348}
 349EXPORT_SYMBOL(jbd2__journal_start);
 350
 351
 352handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
 353{
 354        return jbd2__journal_start(journal, nblocks, GFP_NOFS);
 355}
 356EXPORT_SYMBOL(jbd2_journal_start);
 357
 358
 359/**
 360 * int jbd2_journal_extend() - extend buffer credits.
 361 * @handle:  handle to 'extend'
 362 * @nblocks: nr blocks to try to extend by.
 363 *
 364 * Some transactions, such as large extends and truncates, can be done
 365 * atomically all at once or in several stages.  The operation requests
 366 * a credit for a number of buffer modications in advance, but can
 367 * extend its credit if it needs more.
 368 *
 369 * jbd2_journal_extend tries to give the running handle more buffer credits.
 370 * It does not guarantee that allocation - this is a best-effort only.
 371 * The calling process MUST be able to deal cleanly with a failure to
 372 * extend here.
 373 *
 374 * Return 0 on success, non-zero on failure.
 375 *
 376 * return code < 0 implies an error
 377 * return code > 0 implies normal transaction-full status.
 378 */
 379int jbd2_journal_extend(handle_t *handle, int nblocks)
 380{
 381        transaction_t *transaction = handle->h_transaction;
 382        journal_t *journal = transaction->t_journal;
 383        int result;
 384        int wanted;
 385
 386        result = -EIO;
 387        if (is_handle_aborted(handle))
 388                goto out;
 389
 390        result = 1;
 391
 392        read_lock(&journal->j_state_lock);
 393
 394        /* Don't extend a locked-down transaction! */
 395        if (handle->h_transaction->t_state != T_RUNNING) {
 396                jbd_debug(3, "denied handle %p %d blocks: "
 397                          "transaction not running\n", handle, nblocks);
 398                goto error_out;
 399        }
 400
 401        spin_lock(&transaction->t_handle_lock);
 402        wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks;
 403
 404        if (wanted > journal->j_max_transaction_buffers) {
 405                jbd_debug(3, "denied handle %p %d blocks: "
 406                          "transaction too large\n", handle, nblocks);
 407                goto unlock;
 408        }
 409
 410        if (wanted > __jbd2_log_space_left(journal)) {
 411                jbd_debug(3, "denied handle %p %d blocks: "
 412                          "insufficient log space\n", handle, nblocks);
 413                goto unlock;
 414        }
 415
 416        handle->h_buffer_credits += nblocks;
 417        atomic_add(nblocks, &transaction->t_outstanding_credits);
 418        result = 0;
 419
 420        jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
 421unlock:
 422        spin_unlock(&transaction->t_handle_lock);
 423error_out:
 424        read_unlock(&journal->j_state_lock);
 425out:
 426        return result;
 427}
 428
 429
 430/**
 431 * int jbd2_journal_restart() - restart a handle .
 432 * @handle:  handle to restart
 433 * @nblocks: nr credits requested
 434 *
 435 * Restart a handle for a multi-transaction filesystem
 436 * operation.
 437 *
 438 * If the jbd2_journal_extend() call above fails to grant new buffer credits
 439 * to a running handle, a call to jbd2_journal_restart will commit the
 440 * handle's transaction so far and reattach the handle to a new
 441 * transaction capabable of guaranteeing the requested number of
 442 * credits.
 443 */
 444int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask)
 445{
 446        transaction_t *transaction = handle->h_transaction;
 447        journal_t *journal = transaction->t_journal;
 448        tid_t           tid;
 449        int             need_to_start, ret;
 450
 451        /* If we've had an abort of any type, don't even think about
 452         * actually doing the restart! */
 453        if (is_handle_aborted(handle))
 454                return 0;
 455
 456        /*
 457         * First unlink the handle from its current transaction, and start the
 458         * commit on that.
 459         */
 460        J_ASSERT(atomic_read(&transaction->t_updates) > 0);
 461        J_ASSERT(journal_current_handle() == handle);
 462
 463        read_lock(&journal->j_state_lock);
 464        spin_lock(&transaction->t_handle_lock);
 465        atomic_sub(handle->h_buffer_credits,
 466                   &transaction->t_outstanding_credits);
 467        if (atomic_dec_and_test(&transaction->t_updates))
 468                wake_up(&journal->j_wait_updates);
 469        spin_unlock(&transaction->t_handle_lock);
 470
 471        jbd_debug(2, "restarting handle %p\n", handle);
 472        tid = transaction->t_tid;
 473        need_to_start = !tid_geq(journal->j_commit_request, tid);
 474        read_unlock(&journal->j_state_lock);
 475        if (need_to_start)
 476                jbd2_log_start_commit(journal, tid);
 477
 478        lock_map_release(&handle->h_lockdep_map);
 479        handle->h_buffer_credits = nblocks;
 480        ret = start_this_handle(journal, handle, gfp_mask);
 481        return ret;
 482}
 483EXPORT_SYMBOL(jbd2__journal_restart);
 484
 485
 486int jbd2_journal_restart(handle_t *handle, int nblocks)
 487{
 488        return jbd2__journal_restart(handle, nblocks, GFP_NOFS);
 489}
 490EXPORT_SYMBOL(jbd2_journal_restart);
 491
 492/**
 493 * void jbd2_journal_lock_updates () - establish a transaction barrier.
 494 * @journal:  Journal to establish a barrier on.
 495 *
 496 * This locks out any further updates from being started, and blocks
 497 * until all existing updates have completed, returning only once the
 498 * journal is in a quiescent state with no updates running.
 499 *
 500 * The journal lock should not be held on entry.
 501 */
 502void jbd2_journal_lock_updates(journal_t *journal)
 503{
 504        DEFINE_WAIT(wait);
 505
 506        write_lock(&journal->j_state_lock);
 507        ++journal->j_barrier_count;
 508
 509        /* Wait until there are no running updates */
 510        while (1) {
 511                transaction_t *transaction = journal->j_running_transaction;
 512
 513                if (!transaction)
 514                        break;
 515
 516                spin_lock(&transaction->t_handle_lock);
 517                if (!atomic_read(&transaction->t_updates)) {
 518                        spin_unlock(&transaction->t_handle_lock);
 519                        break;
 520                }
 521                prepare_to_wait(&journal->j_wait_updates, &wait,
 522                                TASK_UNINTERRUPTIBLE);
 523                spin_unlock(&transaction->t_handle_lock);
 524                write_unlock(&journal->j_state_lock);
 525                schedule();
 526                finish_wait(&journal->j_wait_updates, &wait);
 527                write_lock(&journal->j_state_lock);
 528        }
 529        write_unlock(&journal->j_state_lock);
 530
 531        /*
 532         * We have now established a barrier against other normal updates, but
 533         * we also need to barrier against other jbd2_journal_lock_updates() calls
 534         * to make sure that we serialise special journal-locked operations
 535         * too.
 536         */
 537        mutex_lock(&journal->j_barrier);
 538}
 539
 540/**
 541 * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
 542 * @journal:  Journal to release the barrier on.
 543 *
 544 * Release a transaction barrier obtained with jbd2_journal_lock_updates().
 545 *
 546 * Should be called without the journal lock held.
 547 */
 548void jbd2_journal_unlock_updates (journal_t *journal)
 549{
 550        J_ASSERT(journal->j_barrier_count != 0);
 551
 552        mutex_unlock(&journal->j_barrier);
 553        write_lock(&journal->j_state_lock);
 554        --journal->j_barrier_count;
 555        write_unlock(&journal->j_state_lock);
 556        wake_up(&journal->j_wait_transaction_locked);
 557}
 558
 559static void warn_dirty_buffer(struct buffer_head *bh)
 560{
 561        char b[BDEVNAME_SIZE];
 562
 563        printk(KERN_WARNING
 564               "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
 565               "There's a risk of filesystem corruption in case of system "
 566               "crash.\n",
 567               bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
 568}
 569
 570/*
 571 * If the buffer is already part of the current transaction, then there
 572 * is nothing we need to do.  If it is already part of a prior
 573 * transaction which we are still committing to disk, then we need to
 574 * make sure that we do not overwrite the old copy: we do copy-out to
 575 * preserve the copy going to disk.  We also account the buffer against
 576 * the handle's metadata buffer credits (unless the buffer is already
 577 * part of the transaction, that is).
 578 *
 579 */
 580static int
 581do_get_write_access(handle_t *handle, struct journal_head *jh,
 582                        int force_copy)
 583{
 584        struct buffer_head *bh;
 585        transaction_t *transaction;
 586        journal_t *journal;
 587        int error;
 588        char *frozen_buffer = NULL;
 589        int need_copy = 0;
 590
 591        if (is_handle_aborted(handle))
 592                return -EROFS;
 593
 594        transaction = handle->h_transaction;
 595        journal = transaction->t_journal;
 596
 597        jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
 598
 599        JBUFFER_TRACE(jh, "entry");
 600repeat:
 601        bh = jh2bh(jh);
 602
 603        /* @@@ Need to check for errors here at some point. */
 604
 605        lock_buffer(bh);
 606        jbd_lock_bh_state(bh);
 607
 608        /* We now hold the buffer lock so it is safe to query the buffer
 609         * state.  Is the buffer dirty?
 610         *
 611         * If so, there are two possibilities.  The buffer may be
 612         * non-journaled, and undergoing a quite legitimate writeback.
 613         * Otherwise, it is journaled, and we don't expect dirty buffers
 614         * in that state (the buffers should be marked JBD_Dirty
 615         * instead.)  So either the IO is being done under our own
 616         * control and this is a bug, or it's a third party IO such as
 617         * dump(8) (which may leave the buffer scheduled for read ---
 618         * ie. locked but not dirty) or tune2fs (which may actually have
 619         * the buffer dirtied, ugh.)  */
 620
 621        if (buffer_dirty(bh)) {
 622                /*
 623                 * First question: is this buffer already part of the current
 624                 * transaction or the existing committing transaction?
 625                 */
 626                if (jh->b_transaction) {
 627                        J_ASSERT_JH(jh,
 628                                jh->b_transaction == transaction ||
 629                                jh->b_transaction ==
 630                                        journal->j_committing_transaction);
 631                        if (jh->b_next_transaction)
 632                                J_ASSERT_JH(jh, jh->b_next_transaction ==
 633                                                        transaction);
 634                        warn_dirty_buffer(bh);
 635                }
 636                /*
 637                 * In any case we need to clean the dirty flag and we must
 638                 * do it under the buffer lock to be sure we don't race
 639                 * with running write-out.
 640                 */
 641                JBUFFER_TRACE(jh, "Journalling dirty buffer");
 642                clear_buffer_dirty(bh);
 643                set_buffer_jbddirty(bh);
 644        }
 645
 646        unlock_buffer(bh);
 647
 648        error = -EROFS;
 649        if (is_handle_aborted(handle)) {
 650                jbd_unlock_bh_state(bh);
 651                goto out;
 652        }
 653        error = 0;
 654
 655        /*
 656         * The buffer is already part of this transaction if b_transaction or
 657         * b_next_transaction points to it
 658         */
 659        if (jh->b_transaction == transaction ||
 660            jh->b_next_transaction == transaction)
 661                goto done;
 662
 663        /*
 664         * this is the first time this transaction is touching this buffer,
 665         * reset the modified flag
 666         */
 667       jh->b_modified = 0;
 668
 669        /*
 670         * If there is already a copy-out version of this buffer, then we don't
 671         * need to make another one
 672         */
 673        if (jh->b_frozen_data) {
 674                JBUFFER_TRACE(jh, "has frozen data");
 675                J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
 676                jh->b_next_transaction = transaction;
 677                goto done;
 678        }
 679
 680        /* Is there data here we need to preserve? */
 681
 682        if (jh->b_transaction && jh->b_transaction != transaction) {
 683                JBUFFER_TRACE(jh, "owned by older transaction");
 684                J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
 685                J_ASSERT_JH(jh, jh->b_transaction ==
 686                                        journal->j_committing_transaction);
 687
 688                /* There is one case we have to be very careful about.
 689                 * If the committing transaction is currently writing
 690                 * this buffer out to disk and has NOT made a copy-out,
 691                 * then we cannot modify the buffer contents at all
 692                 * right now.  The essence of copy-out is that it is the
 693                 * extra copy, not the primary copy, which gets
 694                 * journaled.  If the primary copy is already going to
 695                 * disk then we cannot do copy-out here. */
 696
 697                if (jh->b_jlist == BJ_Shadow) {
 698                        DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
 699                        wait_queue_head_t *wqh;
 700
 701                        wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
 702
 703                        JBUFFER_TRACE(jh, "on shadow: sleep");
 704                        jbd_unlock_bh_state(bh);
 705                        /* commit wakes up all shadow buffers after IO */
 706                        for ( ; ; ) {
 707                                prepare_to_wait(wqh, &wait.wait,
 708                                                TASK_UNINTERRUPTIBLE);
 709                                if (jh->b_jlist != BJ_Shadow)
 710                                        break;
 711                                schedule();
 712                        }
 713                        finish_wait(wqh, &wait.wait);
 714                        goto repeat;
 715                }
 716
 717                /* Only do the copy if the currently-owning transaction
 718                 * still needs it.  If it is on the Forget list, the
 719                 * committing transaction is past that stage.  The
 720                 * buffer had better remain locked during the kmalloc,
 721                 * but that should be true --- we hold the journal lock
 722                 * still and the buffer is already on the BUF_JOURNAL
 723                 * list so won't be flushed.
 724                 *
 725                 * Subtle point, though: if this is a get_undo_access,
 726                 * then we will be relying on the frozen_data to contain
 727                 * the new value of the committed_data record after the
 728                 * transaction, so we HAVE to force the frozen_data copy
 729                 * in that case. */
 730
 731                if (jh->b_jlist != BJ_Forget || force_copy) {
 732                        JBUFFER_TRACE(jh, "generate frozen data");
 733                        if (!frozen_buffer) {
 734                                JBUFFER_TRACE(jh, "allocate memory for buffer");
 735                                jbd_unlock_bh_state(bh);
 736                                frozen_buffer =
 737                                        jbd2_alloc(jh2bh(jh)->b_size,
 738                                                         GFP_NOFS);
 739                                if (!frozen_buffer) {
 740                                        printk(KERN_EMERG
 741                                               "%s: OOM for frozen_buffer\n",
 742                                               __func__);
 743                                        JBUFFER_TRACE(jh, "oom!");
 744                                        error = -ENOMEM;
 745                                        jbd_lock_bh_state(bh);
 746                                        goto done;
 747                                }
 748                                goto repeat;
 749                        }
 750                        jh->b_frozen_data = frozen_buffer;
 751                        frozen_buffer = NULL;
 752                        need_copy = 1;
 753                }
 754                jh->b_next_transaction = transaction;
 755        }
 756
 757
 758        /*
 759         * Finally, if the buffer is not journaled right now, we need to make
 760         * sure it doesn't get written to disk before the caller actually
 761         * commits the new data
 762         */
 763        if (!jh->b_transaction) {
 764                JBUFFER_TRACE(jh, "no transaction");
 765                J_ASSERT_JH(jh, !jh->b_next_transaction);
 766                jh->b_transaction = transaction;
 767                JBUFFER_TRACE(jh, "file as BJ_Reserved");
 768                spin_lock(&journal->j_list_lock);
 769                __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
 770                spin_unlock(&journal->j_list_lock);
 771        }
 772
 773done:
 774        if (need_copy) {
 775                struct page *page;
 776                int offset;
 777                char *source;
 778
 779                J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
 780                            "Possible IO failure.\n");
 781                page = jh2bh(jh)->b_page;
 782                offset = offset_in_page(jh2bh(jh)->b_data);
 783                source = kmap_atomic(page, KM_USER0);
 784                /* Fire data frozen trigger just before we copy the data */
 785                jbd2_buffer_frozen_trigger(jh, source + offset,
 786                                           jh->b_triggers);
 787                memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
 788                kunmap_atomic(source, KM_USER0);
 789
 790                /*
 791                 * Now that the frozen data is saved off, we need to store
 792                 * any matching triggers.
 793                 */
 794                jh->b_frozen_triggers = jh->b_triggers;
 795        }
 796        jbd_unlock_bh_state(bh);
 797
 798        /*
 799         * If we are about to journal a buffer, then any revoke pending on it is
 800         * no longer valid
 801         */
 802        jbd2_journal_cancel_revoke(handle, jh);
 803
 804out:
 805        if (unlikely(frozen_buffer))    /* It's usually NULL */
 806                jbd2_free(frozen_buffer, bh->b_size);
 807
 808        JBUFFER_TRACE(jh, "exit");
 809        return error;
 810}
 811
 812/**
 813 * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
 814 * @handle: transaction to add buffer modifications to
 815 * @bh:     bh to be used for metadata writes
 816 * @credits: variable that will receive credits for the buffer
 817 *
 818 * Returns an error code or 0 on success.
 819 *
 820 * In full data journalling mode the buffer may be of type BJ_AsyncData,
 821 * because we're write()ing a buffer which is also part of a shared mapping.
 822 */
 823
 824int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
 825{
 826        struct journal_head *jh = jbd2_journal_add_journal_head(bh);
 827        int rc;
 828
 829        /* We do not want to get caught playing with fields which the
 830         * log thread also manipulates.  Make sure that the buffer
 831         * completes any outstanding IO before proceeding. */
 832        rc = do_get_write_access(handle, jh, 0);
 833        jbd2_journal_put_journal_head(jh);
 834        return rc;
 835}
 836
 837
 838/*
 839 * When the user wants to journal a newly created buffer_head
 840 * (ie. getblk() returned a new buffer and we are going to populate it
 841 * manually rather than reading off disk), then we need to keep the
 842 * buffer_head locked until it has been completely filled with new
 843 * data.  In this case, we should be able to make the assertion that
 844 * the bh is not already part of an existing transaction.
 845 *
 846 * The buffer should already be locked by the caller by this point.
 847 * There is no lock ranking violation: it was a newly created,
 848 * unlocked buffer beforehand. */
 849
 850/**
 851 * int jbd2_journal_get_create_access () - notify intent to use newly created bh
 852 * @handle: transaction to new buffer to
 853 * @bh: new buffer.
 854 *
 855 * Call this if you create a new bh.
 856 */
 857int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
 858{
 859        transaction_t *transaction = handle->h_transaction;
 860        journal_t *journal = transaction->t_journal;
 861        struct journal_head *jh = jbd2_journal_add_journal_head(bh);
 862        int err;
 863
 864        jbd_debug(5, "journal_head %p\n", jh);
 865        err = -EROFS;
 866        if (is_handle_aborted(handle))
 867                goto out;
 868        err = 0;
 869
 870        JBUFFER_TRACE(jh, "entry");
 871        /*
 872         * The buffer may already belong to this transaction due to pre-zeroing
 873         * in the filesystem's new_block code.  It may also be on the previous,
 874         * committing transaction's lists, but it HAS to be in Forget state in
 875         * that case: the transaction must have deleted the buffer for it to be
 876         * reused here.
 877         */
 878        jbd_lock_bh_state(bh);
 879        spin_lock(&journal->j_list_lock);
 880        J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
 881                jh->b_transaction == NULL ||
 882                (jh->b_transaction == journal->j_committing_transaction &&
 883                          jh->b_jlist == BJ_Forget)));
 884
 885        J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
 886        J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
 887
 888        if (jh->b_transaction == NULL) {
 889                /*
 890                 * Previous jbd2_journal_forget() could have left the buffer
 891                 * with jbddirty bit set because it was being committed. When
 892                 * the commit finished, we've filed the buffer for
 893                 * checkpointing and marked it dirty. Now we are reallocating
 894                 * the buffer so the transaction freeing it must have
 895                 * committed and so it's safe to clear the dirty bit.
 896                 */
 897                clear_buffer_dirty(jh2bh(jh));
 898                jh->b_transaction = transaction;
 899
 900                /* first access by this transaction */
 901                jh->b_modified = 0;
 902
 903                JBUFFER_TRACE(jh, "file as BJ_Reserved");
 904                __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
 905        } else if (jh->b_transaction == journal->j_committing_transaction) {
 906                /* first access by this transaction */
 907                jh->b_modified = 0;
 908
 909                JBUFFER_TRACE(jh, "set next transaction");
 910                jh->b_next_transaction = transaction;
 911        }
 912        spin_unlock(&journal->j_list_lock);
 913        jbd_unlock_bh_state(bh);
 914
 915        /*
 916         * akpm: I added this.  ext3_alloc_branch can pick up new indirect
 917         * blocks which contain freed but then revoked metadata.  We need
 918         * to cancel the revoke in case we end up freeing it yet again
 919         * and the reallocating as data - this would cause a second revoke,
 920         * which hits an assertion error.
 921         */
 922        JBUFFER_TRACE(jh, "cancelling revoke");
 923        jbd2_journal_cancel_revoke(handle, jh);
 924        jbd2_journal_put_journal_head(jh);
 925out:
 926        return err;
 927}
 928
 929/**
 930 * int jbd2_journal_get_undo_access() -  Notify intent to modify metadata with
 931 *     non-rewindable consequences
 932 * @handle: transaction
 933 * @bh: buffer to undo
 934 * @credits: store the number of taken credits here (if not NULL)
 935 *
 936 * Sometimes there is a need to distinguish between metadata which has
 937 * been committed to disk and that which has not.  The ext3fs code uses
 938 * this for freeing and allocating space, we have to make sure that we
 939 * do not reuse freed space until the deallocation has been committed,
 940 * since if we overwrote that space we would make the delete
 941 * un-rewindable in case of a crash.
 942 *
 943 * To deal with that, jbd2_journal_get_undo_access requests write access to a
 944 * buffer for parts of non-rewindable operations such as delete
 945 * operations on the bitmaps.  The journaling code must keep a copy of
 946 * the buffer's contents prior to the undo_access call until such time
 947 * as we know that the buffer has definitely been committed to disk.
 948 *
 949 * We never need to know which transaction the committed data is part
 950 * of, buffers touched here are guaranteed to be dirtied later and so
 951 * will be committed to a new transaction in due course, at which point
 952 * we can discard the old committed data pointer.
 953 *
 954 * Returns error number or 0 on success.
 955 */
 956int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
 957{
 958        int err;
 959        struct journal_head *jh = jbd2_journal_add_journal_head(bh);
 960        char *committed_data = NULL;
 961
 962        JBUFFER_TRACE(jh, "entry");
 963
 964        /*
 965         * Do this first --- it can drop the journal lock, so we want to
 966         * make sure that obtaining the committed_data is done
 967         * atomically wrt. completion of any outstanding commits.
 968         */
 969        err = do_get_write_access(handle, jh, 1);
 970        if (err)
 971                goto out;
 972
 973repeat:
 974        if (!jh->b_committed_data) {
 975                committed_data = jbd2_alloc(jh2bh(jh)->b_size, GFP_NOFS);
 976                if (!committed_data) {
 977                        printk(KERN_EMERG "%s: No memory for committed data\n",
 978                                __func__);
 979                        err = -ENOMEM;
 980                        goto out;
 981                }
 982        }
 983
 984        jbd_lock_bh_state(bh);
 985        if (!jh->b_committed_data) {
 986                /* Copy out the current buffer contents into the
 987                 * preserved, committed copy. */
 988                JBUFFER_TRACE(jh, "generate b_committed data");
 989                if (!committed_data) {
 990                        jbd_unlock_bh_state(bh);
 991                        goto repeat;
 992                }
 993
 994                jh->b_committed_data = committed_data;
 995                committed_data = NULL;
 996                memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
 997        }
 998        jbd_unlock_bh_state(bh);
 999out:
1000        jbd2_journal_put_journal_head(jh);
1001        if (unlikely(committed_data))
1002                jbd2_free(committed_data, bh->b_size);
1003        return err;
1004}
1005
1006/**
1007 * void jbd2_journal_set_triggers() - Add triggers for commit writeout
1008 * @bh: buffer to trigger on
1009 * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
1010 *
1011 * Set any triggers on this journal_head.  This is always safe, because
1012 * triggers for a committing buffer will be saved off, and triggers for
1013 * a running transaction will match the buffer in that transaction.
1014 *
1015 * Call with NULL to clear the triggers.
1016 */
1017void jbd2_journal_set_triggers(struct buffer_head *bh,
1018                               struct jbd2_buffer_trigger_type *type)
1019{
1020        struct journal_head *jh = bh2jh(bh);
1021
1022        jh->b_triggers = type;
1023}
1024
1025void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
1026                                struct jbd2_buffer_trigger_type *triggers)
1027{
1028        struct buffer_head *bh = jh2bh(jh);
1029
1030        if (!triggers || !triggers->t_frozen)
1031                return;
1032
1033        triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
1034}
1035
1036void jbd2_buffer_abort_trigger(struct journal_head *jh,
1037                               struct jbd2_buffer_trigger_type *triggers)
1038{
1039        if (!triggers || !triggers->t_abort)
1040                return;
1041
1042        triggers->t_abort(triggers, jh2bh(jh));
1043}
1044
1045
1046
1047/**
1048 * int jbd2_journal_dirty_metadata() -  mark a buffer as containing dirty metadata
1049 * @handle: transaction to add buffer to.
1050 * @bh: buffer to mark
1051 *
1052 * mark dirty metadata which needs to be journaled as part of the current
1053 * transaction.
1054 *
1055 * The buffer is placed on the transaction's metadata list and is marked
1056 * as belonging to the transaction.
1057 *
1058 * Returns error number or 0 on success.
1059 *
1060 * Special care needs to be taken if the buffer already belongs to the
1061 * current committing transaction (in which case we should have frozen
1062 * data present for that commit).  In that case, we don't relink the
1063 * buffer: that only gets done when the old transaction finally
1064 * completes its commit.
1065 */
1066int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1067{
1068        transaction_t *transaction = handle->h_transaction;
1069        journal_t *journal = transaction->t_journal;
1070        struct journal_head *jh = bh2jh(bh);
1071
1072        jbd_debug(5, "journal_head %p\n", jh);
1073        JBUFFER_TRACE(jh, "entry");
1074        if (is_handle_aborted(handle))
1075                goto out;
1076
1077        jbd_lock_bh_state(bh);
1078
1079        if (jh->b_modified == 0) {
1080                /*
1081                 * This buffer's got modified and becoming part
1082                 * of the transaction. This needs to be done
1083                 * once a transaction -bzzz
1084                 */
1085                jh->b_modified = 1;
1086                J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
1087                handle->h_buffer_credits--;
1088        }
1089
1090        /*
1091         * fastpath, to avoid expensive locking.  If this buffer is already
1092         * on the running transaction's metadata list there is nothing to do.
1093         * Nobody can take it off again because there is a handle open.
1094         * I _think_ we're OK here with SMP barriers - a mistaken decision will
1095         * result in this test being false, so we go in and take the locks.
1096         */
1097        if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1098                JBUFFER_TRACE(jh, "fastpath");
1099                J_ASSERT_JH(jh, jh->b_transaction ==
1100                                        journal->j_running_transaction);
1101                goto out_unlock_bh;
1102        }
1103
1104        set_buffer_jbddirty(bh);
1105
1106        /*
1107         * Metadata already on the current transaction list doesn't
1108         * need to be filed.  Metadata on another transaction's list must
1109         * be committing, and will be refiled once the commit completes:
1110         * leave it alone for now.
1111         */
1112        if (jh->b_transaction != transaction) {
1113                JBUFFER_TRACE(jh, "already on other transaction");
1114                J_ASSERT_JH(jh, jh->b_transaction ==
1115                                        journal->j_committing_transaction);
1116                J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1117                /* And this case is illegal: we can't reuse another
1118                 * transaction's data buffer, ever. */
1119                goto out_unlock_bh;
1120        }
1121
1122        /* That test should have eliminated the following case: */
1123        J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
1124
1125        JBUFFER_TRACE(jh, "file as BJ_Metadata");
1126        spin_lock(&journal->j_list_lock);
1127        __jbd2_journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1128        spin_unlock(&journal->j_list_lock);
1129out_unlock_bh:
1130        jbd_unlock_bh_state(bh);
1131out:
1132        JBUFFER_TRACE(jh, "exit");
1133        return 0;
1134}
1135
1136/*
1137 * jbd2_journal_release_buffer: undo a get_write_access without any buffer
1138 * updates, if the update decided in the end that it didn't need access.
1139 *
1140 */
1141void
1142jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
1143{
1144        BUFFER_TRACE(bh, "entry");
1145}
1146
1147/**
1148 * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
1149 * @handle: transaction handle
1150 * @bh:     bh to 'forget'
1151 *
1152 * We can only do the bforget if there are no commits pending against the
1153 * buffer.  If the buffer is dirty in the current running transaction we
1154 * can safely unlink it.
1155 *
1156 * bh may not be a journalled buffer at all - it may be a non-JBD
1157 * buffer which came off the hashtable.  Check for this.
1158 *
1159 * Decrements bh->b_count by one.
1160 *
1161 * Allow this call even if the handle has aborted --- it may be part of
1162 * the caller's cleanup after an abort.
1163 */
1164int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
1165{
1166        transaction_t *transaction = handle->h_transaction;
1167        journal_t *journal = transaction->t_journal;
1168        struct journal_head *jh;
1169        int drop_reserve = 0;
1170        int err = 0;
1171        int was_modified = 0;
1172
1173        BUFFER_TRACE(bh, "entry");
1174
1175        jbd_lock_bh_state(bh);
1176        spin_lock(&journal->j_list_lock);
1177
1178        if (!buffer_jbd(bh))
1179                goto not_jbd;
1180        jh = bh2jh(bh);
1181
1182        /* Critical error: attempting to delete a bitmap buffer, maybe?
1183         * Don't do any jbd operations, and return an error. */
1184        if (!J_EXPECT_JH(jh, !jh->b_committed_data,
1185                         "inconsistent data on disk")) {
1186                err = -EIO;
1187                goto not_jbd;
1188        }
1189
1190        /* keep track of wether or not this transaction modified us */
1191        was_modified = jh->b_modified;
1192
1193        /*
1194         * The buffer's going from the transaction, we must drop
1195         * all references -bzzz
1196         */
1197        jh->b_modified = 0;
1198
1199        if (jh->b_transaction == handle->h_transaction) {
1200                J_ASSERT_JH(jh, !jh->b_frozen_data);
1201
1202                /* If we are forgetting a buffer which is already part
1203                 * of this transaction, then we can just drop it from
1204                 * the transaction immediately. */
1205                clear_buffer_dirty(bh);
1206                clear_buffer_jbddirty(bh);
1207
1208                JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1209
1210                /*
1211                 * we only want to drop a reference if this transaction
1212                 * modified the buffer
1213                 */
1214                if (was_modified)
1215                        drop_reserve = 1;
1216
1217                /*
1218                 * We are no longer going to journal this buffer.
1219                 * However, the commit of this transaction is still
1220                 * important to the buffer: the delete that we are now
1221                 * processing might obsolete an old log entry, so by
1222                 * committing, we can satisfy the buffer's checkpoint.
1223                 *
1224                 * So, if we have a checkpoint on the buffer, we should
1225                 * now refile the buffer on our BJ_Forget list so that
1226                 * we know to remove the checkpoint after we commit.
1227                 */
1228
1229                if (jh->b_cp_transaction) {
1230                        __jbd2_journal_temp_unlink_buffer(jh);
1231                        __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1232                } else {
1233                        __jbd2_journal_unfile_buffer(jh);
1234                        jbd2_journal_remove_journal_head(bh);
1235                        __brelse(bh);
1236                        if (!buffer_jbd(bh)) {
1237                                spin_unlock(&journal->j_list_lock);
1238                                jbd_unlock_bh_state(bh);
1239                                __bforget(bh);
1240                                goto drop;
1241                        }
1242                }
1243        } else if (jh->b_transaction) {
1244                J_ASSERT_JH(jh, (jh->b_transaction ==
1245                                 journal->j_committing_transaction));
1246                /* However, if the buffer is still owned by a prior
1247                 * (committing) transaction, we can't drop it yet... */
1248                JBUFFER_TRACE(jh, "belongs to older transaction");
1249                /* ... but we CAN drop it from the new transaction if we
1250                 * have also modified it since the original commit. */
1251
1252                if (jh->b_next_transaction) {
1253                        J_ASSERT(jh->b_next_transaction == transaction);
1254                        jh->b_next_transaction = NULL;
1255
1256                        /*
1257                         * only drop a reference if this transaction modified
1258                         * the buffer
1259                         */
1260                        if (was_modified)
1261                                drop_reserve = 1;
1262                }
1263        }
1264
1265not_jbd:
1266        spin_unlock(&journal->j_list_lock);
1267        jbd_unlock_bh_state(bh);
1268        __brelse(bh);
1269drop:
1270        if (drop_reserve) {
1271                /* no need to reserve log space for this block -bzzz */
1272                handle->h_buffer_credits++;
1273        }
1274        return err;
1275}
1276
1277/**
1278 * int jbd2_journal_stop() - complete a transaction
1279 * @handle: tranaction to complete.
1280 *
1281 * All done for a particular handle.
1282 *
1283 * There is not much action needed here.  We just return any remaining
1284 * buffer credits to the transaction and remove the handle.  The only
1285 * complication is that we need to start a commit operation if the
1286 * filesystem is marked for synchronous update.
1287 *
1288 * jbd2_journal_stop itself will not usually return an error, but it may
1289 * do so in unusual circumstances.  In particular, expect it to
1290 * return -EIO if a jbd2_journal_abort has been executed since the
1291 * transaction began.
1292 */
1293int jbd2_journal_stop(handle_t *handle)
1294{
1295        transaction_t *transaction = handle->h_transaction;
1296        journal_t *journal = transaction->t_journal;
1297        int err, wait_for_commit = 0;
1298        tid_t tid;
1299        pid_t pid;
1300
1301        J_ASSERT(journal_current_handle() == handle);
1302
1303        if (is_handle_aborted(handle))
1304                err = -EIO;
1305        else {
1306                J_ASSERT(atomic_read(&transaction->t_updates) > 0);
1307                err = 0;
1308        }
1309
1310        if (--handle->h_ref > 0) {
1311                jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1312                          handle->h_ref);
1313                return err;
1314        }
1315
1316        jbd_debug(4, "Handle %p going down\n", handle);
1317
1318        /*
1319         * Implement synchronous transaction batching.  If the handle
1320         * was synchronous, don't force a commit immediately.  Let's
1321         * yield and let another thread piggyback onto this
1322         * transaction.  Keep doing that while new threads continue to
1323         * arrive.  It doesn't cost much - we're about to run a commit
1324         * and sleep on IO anyway.  Speeds up many-threaded, many-dir
1325         * operations by 30x or more...
1326         *
1327         * We try and optimize the sleep time against what the
1328         * underlying disk can do, instead of having a static sleep
1329         * time.  This is useful for the case where our storage is so
1330         * fast that it is more optimal to go ahead and force a flush
1331         * and wait for the transaction to be committed than it is to
1332         * wait for an arbitrary amount of time for new writers to
1333         * join the transaction.  We achieve this by measuring how
1334         * long it takes to commit a transaction, and compare it with
1335         * how long this transaction has been running, and if run time
1336         * < commit time then we sleep for the delta and commit.  This
1337         * greatly helps super fast disks that would see slowdowns as
1338         * more threads started doing fsyncs.
1339         *
1340         * But don't do this if this process was the most recent one
1341         * to perform a synchronous write.  We do this to detect the
1342         * case where a single process is doing a stream of sync
1343         * writes.  No point in waiting for joiners in that case.
1344         */
1345        pid = current->pid;
1346        if (handle->h_sync && journal->j_last_sync_writer != pid) {
1347                u64 commit_time, trans_time;
1348
1349                journal->j_last_sync_writer = pid;
1350
1351                read_lock(&journal->j_state_lock);
1352                commit_time = journal->j_average_commit_time;
1353                read_unlock(&journal->j_state_lock);
1354
1355                trans_time = ktime_to_ns(ktime_sub(ktime_get(),
1356                                                   transaction->t_start_time));
1357
1358                commit_time = max_t(u64, commit_time,
1359                                    1000*journal->j_min_batch_time);
1360                commit_time = min_t(u64, commit_time,
1361                                    1000*journal->j_max_batch_time);
1362
1363                if (trans_time < commit_time) {
1364                        ktime_t expires = ktime_add_ns(ktime_get(),
1365                                                       commit_time);
1366                        set_current_state(TASK_UNINTERRUPTIBLE);
1367                        schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
1368                }
1369        }
1370
1371        if (handle->h_sync)
1372                transaction->t_synchronous_commit = 1;
1373        current->journal_info = NULL;
1374        atomic_sub(handle->h_buffer_credits,
1375                   &transaction->t_outstanding_credits);
1376
1377        /*
1378         * If the handle is marked SYNC, we need to set another commit
1379         * going!  We also want to force a commit if the current
1380         * transaction is occupying too much of the log, or if the
1381         * transaction is too old now.
1382         */
1383        if (handle->h_sync ||
1384            (atomic_read(&transaction->t_outstanding_credits) >
1385             journal->j_max_transaction_buffers) ||
1386            time_after_eq(jiffies, transaction->t_expires)) {
1387                /* Do this even for aborted journals: an abort still
1388                 * completes the commit thread, it just doesn't write
1389                 * anything to disk. */
1390
1391                jbd_debug(2, "transaction too old, requesting commit for "
1392                                        "handle %p\n", handle);
1393                /* This is non-blocking */
1394                jbd2_log_start_commit(journal, transaction->t_tid);
1395
1396                /*
1397                 * Special case: JBD2_SYNC synchronous updates require us
1398                 * to wait for the commit to complete.
1399                 */
1400                if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1401                        wait_for_commit = 1;
1402        }
1403
1404        /*
1405         * Once we drop t_updates, if it goes to zero the transaction
1406         * could start commiting on us and eventually disappear.  So
1407         * once we do this, we must not dereference transaction
1408         * pointer again.
1409         */
1410        tid = transaction->t_tid;
1411        if (atomic_dec_and_test(&transaction->t_updates)) {
1412                wake_up(&journal->j_wait_updates);
1413                if (journal->j_barrier_count)
1414                        wake_up(&journal->j_wait_transaction_locked);
1415        }
1416
1417        if (wait_for_commit)
1418                err = jbd2_log_wait_commit(journal, tid);
1419
1420        lock_map_release(&handle->h_lockdep_map);
1421
1422        jbd2_free_handle(handle);
1423        return err;
1424}
1425
1426/**
1427 * int jbd2_journal_force_commit() - force any uncommitted transactions
1428 * @journal: journal to force
1429 *
1430 * For synchronous operations: force any uncommitted transactions
1431 * to disk.  May seem kludgy, but it reuses all the handle batching
1432 * code in a very simple manner.
1433 */
1434int jbd2_journal_force_commit(journal_t *journal)
1435{
1436        handle_t *handle;
1437        int ret;
1438
1439        handle = jbd2_journal_start(journal, 1);
1440        if (IS_ERR(handle)) {
1441                ret = PTR_ERR(handle);
1442        } else {
1443                handle->h_sync = 1;
1444                ret = jbd2_journal_stop(handle);
1445        }
1446        return ret;
1447}
1448
1449/*
1450 *
1451 * List management code snippets: various functions for manipulating the
1452 * transaction buffer lists.
1453 *
1454 */
1455
1456/*
1457 * Append a buffer to a transaction list, given the transaction's list head
1458 * pointer.
1459 *
1460 * j_list_lock is held.
1461 *
1462 * jbd_lock_bh_state(jh2bh(jh)) is held.
1463 */
1464
1465static inline void
1466__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1467{
1468        if (!*list) {
1469                jh->b_tnext = jh->b_tprev = jh;
1470                *list = jh;
1471        } else {
1472                /* Insert at the tail of the list to preserve order */
1473                struct journal_head *first = *list, *last = first->b_tprev;
1474                jh->b_tprev = last;
1475                jh->b_tnext = first;
1476                last->b_tnext = first->b_tprev = jh;
1477        }
1478}
1479
1480/*
1481 * Remove a buffer from a transaction list, given the transaction's list
1482 * head pointer.
1483 *
1484 * Called with j_list_lock held, and the journal may not be locked.
1485 *
1486 * jbd_lock_bh_state(jh2bh(jh)) is held.
1487 */
1488
1489static inline void
1490__blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1491{
1492        if (*list == jh) {
1493                *list = jh->b_tnext;
1494                if (*list == jh)
1495                        *list = NULL;
1496        }
1497        jh->b_tprev->b_tnext = jh->b_tnext;
1498        jh->b_tnext->b_tprev = jh->b_tprev;
1499}
1500
1501/*
1502 * Remove a buffer from the appropriate transaction list.
1503 *
1504 * Note that this function can *change* the value of
1505 * bh->b_transaction->t_buffers, t_forget, t_iobuf_list, t_shadow_list,
1506 * t_log_list or t_reserved_list.  If the caller is holding onto a copy of one
1507 * of these pointers, it could go bad.  Generally the caller needs to re-read
1508 * the pointer from the transaction_t.
1509 *
1510 * Called under j_list_lock.  The journal may not be locked.
1511 */
1512void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
1513{
1514        struct journal_head **list = NULL;
1515        transaction_t *transaction;
1516        struct buffer_head *bh = jh2bh(jh);
1517
1518        J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1519        transaction = jh->b_transaction;
1520        if (transaction)
1521                assert_spin_locked(&transaction->t_journal->j_list_lock);
1522
1523        J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1524        if (jh->b_jlist != BJ_None)
1525                J_ASSERT_JH(jh, transaction != NULL);
1526
1527        switch (jh->b_jlist) {
1528        case BJ_None:
1529                return;
1530        case BJ_Metadata:
1531                transaction->t_nr_buffers--;
1532                J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1533                list = &transaction->t_buffers;
1534                break;
1535        case BJ_Forget:
1536                list = &transaction->t_forget;
1537                break;
1538        case BJ_IO:
1539                list = &transaction->t_iobuf_list;
1540                break;
1541        case BJ_Shadow:
1542                list = &transaction->t_shadow_list;
1543                break;
1544        case BJ_LogCtl:
1545                list = &transaction->t_log_list;
1546                break;
1547        case BJ_Reserved:
1548                list = &transaction->t_reserved_list;
1549                break;
1550        }
1551
1552        __blist_del_buffer(list, jh);
1553        jh->b_jlist = BJ_None;
1554        if (test_clear_buffer_jbddirty(bh))
1555                mark_buffer_dirty(bh);  /* Expose it to the VM */
1556}
1557
1558void __jbd2_journal_unfile_buffer(struct journal_head *jh)
1559{
1560        __jbd2_journal_temp_unlink_buffer(jh);
1561        jh->b_transaction = NULL;
1562}
1563
1564void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1565{
1566        jbd_lock_bh_state(jh2bh(jh));
1567        spin_lock(&journal->j_list_lock);
1568        __jbd2_journal_unfile_buffer(jh);
1569        spin_unlock(&journal->j_list_lock);
1570        jbd_unlock_bh_state(jh2bh(jh));
1571}
1572
1573/*
1574 * Called from jbd2_journal_try_to_free_buffers().
1575 *
1576 * Called under jbd_lock_bh_state(bh)
1577 */
1578static void
1579__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1580{
1581        struct journal_head *jh;
1582
1583        jh = bh2jh(bh);
1584
1585        if (buffer_locked(bh) || buffer_dirty(bh))
1586                goto out;
1587
1588        if (jh->b_next_transaction != NULL)
1589                goto out;
1590
1591        spin_lock(&journal->j_list_lock);
1592        if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
1593                /* written-back checkpointed metadata buffer */
1594                if (jh->b_jlist == BJ_None) {
1595                        JBUFFER_TRACE(jh, "remove from checkpoint list");
1596                        __jbd2_journal_remove_checkpoint(jh);
1597                        jbd2_journal_remove_journal_head(bh);
1598                        __brelse(bh);
1599                }
1600        }
1601        spin_unlock(&journal->j_list_lock);
1602out:
1603        return;
1604}
1605
1606/**
1607 * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
1608 * @journal: journal for operation
1609 * @page: to try and free
1610 * @gfp_mask: we use the mask to detect how hard should we try to release
1611 * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
1612 * release the buffers.
1613 *
1614 *
1615 * For all the buffers on this page,
1616 * if they are fully written out ordered data, move them onto BUF_CLEAN
1617 * so try_to_free_buffers() can reap them.
1618 *
1619 * This function returns non-zero if we wish try_to_free_buffers()
1620 * to be called. We do this if the page is releasable by try_to_free_buffers().
1621 * We also do it if the page has locked or dirty buffers and the caller wants
1622 * us to perform sync or async writeout.
1623 *
1624 * This complicates JBD locking somewhat.  We aren't protected by the
1625 * BKL here.  We wish to remove the buffer from its committing or
1626 * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
1627 *
1628 * This may *change* the value of transaction_t->t_datalist, so anyone
1629 * who looks at t_datalist needs to lock against this function.
1630 *
1631 * Even worse, someone may be doing a jbd2_journal_dirty_data on this
1632 * buffer.  So we need to lock against that.  jbd2_journal_dirty_data()
1633 * will come out of the lock with the buffer dirty, which makes it
1634 * ineligible for release here.
1635 *
1636 * Who else is affected by this?  hmm...  Really the only contender
1637 * is do_get_write_access() - it could be looking at the buffer while
1638 * journal_try_to_free_buffer() is changing its state.  But that
1639 * cannot happen because we never reallocate freed data as metadata
1640 * while the data is part of a transaction.  Yes?
1641 *
1642 * Return 0 on failure, 1 on success
1643 */
1644int jbd2_journal_try_to_free_buffers(journal_t *journal,
1645                                struct page *page, gfp_t gfp_mask)
1646{
1647        struct buffer_head *head;
1648        struct buffer_head *bh;
1649        int ret = 0;
1650
1651        J_ASSERT(PageLocked(page));
1652
1653        head = page_buffers(page);
1654        bh = head;
1655        do {
1656                struct journal_head *jh;
1657
1658                /*
1659                 * We take our own ref against the journal_head here to avoid
1660                 * having to add tons of locking around each instance of
1661                 * jbd2_journal_remove_journal_head() and
1662                 * jbd2_journal_put_journal_head().
1663                 */
1664                jh = jbd2_journal_grab_journal_head(bh);
1665                if (!jh)
1666                        continue;
1667
1668                jbd_lock_bh_state(bh);
1669                __journal_try_to_free_buffer(journal, bh);
1670                jbd2_journal_put_journal_head(jh);
1671                jbd_unlock_bh_state(bh);
1672                if (buffer_jbd(bh))
1673                        goto busy;
1674        } while ((bh = bh->b_this_page) != head);
1675
1676        ret = try_to_free_buffers(page);
1677
1678busy:
1679        return ret;
1680}
1681
1682/*
1683 * This buffer is no longer needed.  If it is on an older transaction's
1684 * checkpoint list we need to record it on this transaction's forget list
1685 * to pin this buffer (and hence its checkpointing transaction) down until
1686 * this transaction commits.  If the buffer isn't on a checkpoint list, we
1687 * release it.
1688 * Returns non-zero if JBD no longer has an interest in the buffer.
1689 *
1690 * Called under j_list_lock.
1691 *
1692 * Called under jbd_lock_bh_state(bh).
1693 */
1694static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1695{
1696        int may_free = 1;
1697        struct buffer_head *bh = jh2bh(jh);
1698
1699        __jbd2_journal_unfile_buffer(jh);
1700
1701        if (jh->b_cp_transaction) {
1702                JBUFFER_TRACE(jh, "on running+cp transaction");
1703                /*
1704                 * We don't want to write the buffer anymore, clear the
1705                 * bit so that we don't confuse checks in
1706                 * __journal_file_buffer
1707                 */
1708                clear_buffer_dirty(bh);
1709                __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
1710                may_free = 0;
1711        } else {
1712                JBUFFER_TRACE(jh, "on running transaction");
1713                jbd2_journal_remove_journal_head(bh);
1714                __brelse(bh);
1715        }
1716        return may_free;
1717}
1718
1719/*
1720 * jbd2_journal_invalidatepage
1721 *
1722 * This code is tricky.  It has a number of cases to deal with.
1723 *
1724 * There are two invariants which this code relies on:
1725 *
1726 * i_size must be updated on disk before we start calling invalidatepage on the
1727 * data.
1728 *
1729 *  This is done in ext3 by defining an ext3_setattr method which
1730 *  updates i_size before truncate gets going.  By maintaining this
1731 *  invariant, we can be sure that it is safe to throw away any buffers
1732 *  attached to the current transaction: once the transaction commits,
1733 *  we know that the data will not be needed.
1734 *
1735 *  Note however that we can *not* throw away data belonging to the
1736 *  previous, committing transaction!
1737 *
1738 * Any disk blocks which *are* part of the previous, committing
1739 * transaction (and which therefore cannot be discarded immediately) are
1740 * not going to be reused in the new running transaction
1741 *
1742 *  The bitmap committed_data images guarantee this: any block which is
1743 *  allocated in one transaction and removed in the next will be marked
1744 *  as in-use in the committed_data bitmap, so cannot be reused until
1745 *  the next transaction to delete the block commits.  This means that
1746 *  leaving committing buffers dirty is quite safe: the disk blocks
1747 *  cannot be reallocated to a different file and so buffer aliasing is
1748 *  not possible.
1749 *
1750 *
1751 * The above applies mainly to ordered data mode.  In writeback mode we
1752 * don't make guarantees about the order in which data hits disk --- in
1753 * particular we don't guarantee that new dirty data is flushed before
1754 * transaction commit --- so it is always safe just to discard data
1755 * immediately in that mode.  --sct
1756 */
1757
1758/*
1759 * The journal_unmap_buffer helper function returns zero if the buffer
1760 * concerned remains pinned as an anonymous buffer belonging to an older
1761 * transaction.
1762 *
1763 * We're outside-transaction here.  Either or both of j_running_transaction
1764 * and j_committing_transaction may be NULL.
1765 */
1766static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1767{
1768        transaction_t *transaction;
1769        struct journal_head *jh;
1770        int may_free = 1;
1771        int ret;
1772
1773        BUFFER_TRACE(bh, "entry");
1774
1775        /*
1776         * It is safe to proceed here without the j_list_lock because the
1777         * buffers cannot be stolen by try_to_free_buffers as long as we are
1778         * holding the page lock. --sct
1779         */
1780
1781        if (!buffer_jbd(bh))
1782                goto zap_buffer_unlocked;
1783
1784        /* OK, we have data buffer in journaled mode */
1785        write_lock(&journal->j_state_lock);
1786        jbd_lock_bh_state(bh);
1787        spin_lock(&journal->j_list_lock);
1788
1789        jh = jbd2_journal_grab_journal_head(bh);
1790        if (!jh)
1791                goto zap_buffer_no_jh;
1792
1793        /*
1794         * We cannot remove the buffer from checkpoint lists until the
1795         * transaction adding inode to orphan list (let's call it T)
1796         * is committed.  Otherwise if the transaction changing the
1797         * buffer would be cleaned from the journal before T is
1798         * committed, a crash will cause that the correct contents of
1799         * the buffer will be lost.  On the other hand we have to
1800         * clear the buffer dirty bit at latest at the moment when the
1801         * transaction marking the buffer as freed in the filesystem
1802         * structures is committed because from that moment on the
1803         * buffer can be reallocated and used by a different page.
1804         * Since the block hasn't been freed yet but the inode has
1805         * already been added to orphan list, it is safe for us to add
1806         * the buffer to BJ_Forget list of the newest transaction.
1807         */
1808        transaction = jh->b_transaction;
1809        if (transaction == NULL) {
1810                /* First case: not on any transaction.  If it
1811                 * has no checkpoint link, then we can zap it:
1812                 * it's a writeback-mode buffer so we don't care
1813                 * if it hits disk safely. */
1814                if (!jh->b_cp_transaction) {
1815                        JBUFFER_TRACE(jh, "not on any transaction: zap");
1816                        goto zap_buffer;
1817                }
1818
1819                if (!buffer_dirty(bh)) {
1820                        /* bdflush has written it.  We can drop it now */
1821                        goto zap_buffer;
1822                }
1823
1824                /* OK, it must be in the journal but still not
1825                 * written fully to disk: it's metadata or
1826                 * journaled data... */
1827
1828                if (journal->j_running_transaction) {
1829                        /* ... and once the current transaction has
1830                         * committed, the buffer won't be needed any
1831                         * longer. */
1832                        JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1833                        ret = __dispose_buffer(jh,
1834                                        journal->j_running_transaction);
1835                        jbd2_journal_put_journal_head(jh);
1836                        spin_unlock(&journal->j_list_lock);
1837                        jbd_unlock_bh_state(bh);
1838                        write_unlock(&journal->j_state_lock);
1839                        return ret;
1840                } else {
1841                        /* There is no currently-running transaction. So the
1842                         * orphan record which we wrote for this file must have
1843                         * passed into commit.  We must attach this buffer to
1844                         * the committing transaction, if it exists. */
1845                        if (journal->j_committing_transaction) {
1846                                JBUFFER_TRACE(jh, "give to committing trans");
1847                                ret = __dispose_buffer(jh,
1848                                        journal->j_committing_transaction);
1849                                jbd2_journal_put_journal_head(jh);
1850                                spin_unlock(&journal->j_list_lock);
1851                                jbd_unlock_bh_state(bh);
1852                                write_unlock(&journal->j_state_lock);
1853                                return ret;
1854                        } else {
1855                                /* The orphan record's transaction has
1856                                 * committed.  We can cleanse this buffer */
1857                                clear_buffer_jbddirty(bh);
1858                                goto zap_buffer;
1859                        }
1860                }
1861        } else if (transaction == journal->j_committing_transaction) {
1862                JBUFFER_TRACE(jh, "on committing transaction");
1863                /*
1864                 * The buffer is committing, we simply cannot touch
1865                 * it. So we just set j_next_transaction to the
1866                 * running transaction (if there is one) and mark
1867                 * buffer as freed so that commit code knows it should
1868                 * clear dirty bits when it is done with the buffer.
1869                 */
1870                set_buffer_freed(bh);
1871                if (journal->j_running_transaction && buffer_jbddirty(bh))
1872                        jh->b_next_transaction = journal->j_running_transaction;
1873                jbd2_journal_put_journal_head(jh);
1874                spin_unlock(&journal->j_list_lock);
1875                jbd_unlock_bh_state(bh);
1876                write_unlock(&journal->j_state_lock);
1877                return 0;
1878        } else {
1879                /* Good, the buffer belongs to the running transaction.
1880                 * We are writing our own transaction's data, not any
1881                 * previous one's, so it is safe to throw it away
1882                 * (remember that we expect the filesystem to have set
1883                 * i_size already for this truncate so recovery will not
1884                 * expose the disk blocks we are discarding here.) */
1885                J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1886                JBUFFER_TRACE(jh, "on running transaction");
1887                may_free = __dispose_buffer(jh, transaction);
1888        }
1889
1890zap_buffer:
1891        jbd2_journal_put_journal_head(jh);
1892zap_buffer_no_jh:
1893        spin_unlock(&journal->j_list_lock);
1894        jbd_unlock_bh_state(bh);
1895        write_unlock(&journal->j_state_lock);
1896zap_buffer_unlocked:
1897        clear_buffer_dirty(bh);
1898        J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1899        clear_buffer_mapped(bh);
1900        clear_buffer_req(bh);
1901        clear_buffer_new(bh);
1902        bh->b_bdev = NULL;
1903        return may_free;
1904}
1905
1906/**
1907 * void jbd2_journal_invalidatepage()
1908 * @journal: journal to use for flush...
1909 * @page:    page to flush
1910 * @offset:  length of page to invalidate.
1911 *
1912 * Reap page buffers containing data after offset in page.
1913 *
1914 */
1915void jbd2_journal_invalidatepage(journal_t *journal,
1916                      struct page *page,
1917                      unsigned long offset)
1918{
1919        struct buffer_head *head, *bh, *next;
1920        unsigned int curr_off = 0;
1921        int may_free = 1;
1922
1923        if (!PageLocked(page))
1924                BUG();
1925        if (!page_has_buffers(page))
1926                return;
1927
1928        /* We will potentially be playing with lists other than just the
1929         * data lists (especially for journaled data mode), so be
1930         * cautious in our locking. */
1931
1932        head = bh = page_buffers(page);
1933        do {
1934                unsigned int next_off = curr_off + bh->b_size;
1935                next = bh->b_this_page;
1936
1937                if (offset <= curr_off) {
1938                        /* This block is wholly outside the truncation point */
1939                        lock_buffer(bh);
1940                        may_free &= journal_unmap_buffer(journal, bh);
1941                        unlock_buffer(bh);
1942                }
1943                curr_off = next_off;
1944                bh = next;
1945
1946        } while (bh != head);
1947
1948        if (!offset) {
1949                if (may_free && try_to_free_buffers(page))
1950                        J_ASSERT(!page_has_buffers(page));
1951        }
1952}
1953
1954/*
1955 * File a buffer on the given transaction list.
1956 */
1957void __jbd2_journal_file_buffer(struct journal_head *jh,
1958                        transaction_t *transaction, int jlist)
1959{
1960        struct journal_head **list = NULL;
1961        int was_dirty = 0;
1962        struct buffer_head *bh = jh2bh(jh);
1963
1964        J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1965        assert_spin_locked(&transaction->t_journal->j_list_lock);
1966
1967        J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1968        J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1969                                jh->b_transaction == NULL);
1970
1971        if (jh->b_transaction && jh->b_jlist == jlist)
1972                return;
1973
1974        if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
1975            jlist == BJ_Shadow || jlist == BJ_Forget) {
1976                /*
1977                 * For metadata buffers, we track dirty bit in buffer_jbddirty
1978                 * instead of buffer_dirty. We should not see a dirty bit set
1979                 * here because we clear it in do_get_write_access but e.g.
1980                 * tune2fs can modify the sb and set the dirty bit at any time
1981                 * so we try to gracefully handle that.
1982                 */
1983                if (buffer_dirty(bh))
1984                        warn_dirty_buffer(bh);
1985                if (test_clear_buffer_dirty(bh) ||
1986                    test_clear_buffer_jbddirty(bh))
1987                        was_dirty = 1;
1988        }
1989
1990        if (jh->b_transaction)
1991                __jbd2_journal_temp_unlink_buffer(jh);
1992        jh->b_transaction = transaction;
1993
1994        switch (jlist) {
1995        case BJ_None:
1996                J_ASSERT_JH(jh, !jh->b_committed_data);
1997                J_ASSERT_JH(jh, !jh->b_frozen_data);
1998                return;
1999        case BJ_Metadata:
2000                transaction->t_nr_buffers++;
2001                list = &transaction->t_buffers;
2002                break;
2003        case BJ_Forget:
2004                list = &transaction->t_forget;
2005                break;
2006        case BJ_IO:
2007                list = &transaction->t_iobuf_list;
2008                break;
2009        case BJ_Shadow:
2010                list = &transaction->t_shadow_list;
2011                break;
2012        case BJ_LogCtl:
2013                list = &transaction->t_log_list;
2014                break;
2015        case BJ_Reserved:
2016                list = &transaction->t_reserved_list;
2017                break;
2018        }
2019
2020        __blist_add_buffer(list, jh);
2021        jh->b_jlist = jlist;
2022
2023        if (was_dirty)
2024                set_buffer_jbddirty(bh);
2025}
2026
2027void jbd2_journal_file_buffer(struct journal_head *jh,
2028                                transaction_t *transaction, int jlist)
2029{
2030        jbd_lock_bh_state(jh2bh(jh));
2031        spin_lock(&transaction->t_journal->j_list_lock);
2032        __jbd2_journal_file_buffer(jh, transaction, jlist);
2033        spin_unlock(&transaction->t_journal->j_list_lock);
2034        jbd_unlock_bh_state(jh2bh(jh));
2035}
2036
2037/*
2038 * Remove a buffer from its current buffer list in preparation for
2039 * dropping it from its current transaction entirely.  If the buffer has
2040 * already started to be used by a subsequent transaction, refile the
2041 * buffer on that transaction's metadata list.
2042 *
2043 * Called under journal->j_list_lock
2044 *
2045 * Called under jbd_lock_bh_state(jh2bh(jh))
2046 */
2047void __jbd2_journal_refile_buffer(struct journal_head *jh)
2048{
2049        int was_dirty, jlist;
2050        struct buffer_head *bh = jh2bh(jh);
2051
2052        J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2053        if (jh->b_transaction)
2054                assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2055
2056        /* If the buffer is now unused, just drop it. */
2057        if (jh->b_next_transaction == NULL) {
2058                __jbd2_journal_unfile_buffer(jh);
2059                return;
2060        }
2061
2062        /*
2063         * It has been modified by a later transaction: add it to the new
2064         * transaction's metadata list.
2065         */
2066
2067        was_dirty = test_clear_buffer_jbddirty(bh);
2068        __jbd2_journal_temp_unlink_buffer(jh);
2069        jh->b_transaction = jh->b_next_transaction;
2070        jh->b_next_transaction = NULL;
2071        if (buffer_freed(bh))
2072                jlist = BJ_Forget;
2073        else if (jh->b_modified)
2074                jlist = BJ_Metadata;
2075        else
2076                jlist = BJ_Reserved;
2077        __jbd2_journal_file_buffer(jh, jh->b_transaction, jlist);
2078        J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2079
2080        if (was_dirty)
2081                set_buffer_jbddirty(bh);
2082}
2083
2084/*
2085 * For the unlocked version of this call, also make sure that any
2086 * hanging journal_head is cleaned up if necessary.
2087 *
2088 * __jbd2_journal_refile_buffer is usually called as part of a single locked
2089 * operation on a buffer_head, in which the caller is probably going to
2090 * be hooking the journal_head onto other lists.  In that case it is up
2091 * to the caller to remove the journal_head if necessary.  For the
2092 * unlocked jbd2_journal_refile_buffer call, the caller isn't going to be
2093 * doing anything else to the buffer so we need to do the cleanup
2094 * ourselves to avoid a jh leak.
2095 *
2096 * *** The journal_head may be freed by this call! ***
2097 */
2098void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2099{
2100        struct buffer_head *bh = jh2bh(jh);
2101
2102        jbd_lock_bh_state(bh);
2103        spin_lock(&journal->j_list_lock);
2104
2105        __jbd2_journal_refile_buffer(jh);
2106        jbd_unlock_bh_state(bh);
2107        jbd2_journal_remove_journal_head(bh);
2108
2109        spin_unlock(&journal->j_list_lock);
2110        __brelse(bh);
2111}
2112
2113/*
2114 * File inode in the inode list of the handle's transaction
2115 */
2116int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode)
2117{
2118        transaction_t *transaction = handle->h_transaction;
2119        journal_t *journal = transaction->t_journal;
2120
2121        if (is_handle_aborted(handle))
2122                return -EIO;
2123
2124        jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
2125                        transaction->t_tid);
2126
2127        /*
2128         * First check whether inode isn't already on the transaction's
2129         * lists without taking the lock. Note that this check is safe
2130         * without the lock as we cannot race with somebody removing inode
2131         * from the transaction. The reason is that we remove inode from the
2132         * transaction only in journal_release_jbd_inode() and when we commit
2133         * the transaction. We are guarded from the first case by holding
2134         * a reference to the inode. We are safe against the second case
2135         * because if jinode->i_transaction == transaction, commit code
2136         * cannot touch the transaction because we hold reference to it,
2137         * and if jinode->i_next_transaction == transaction, commit code
2138         * will only file the inode where we want it.
2139         */
2140        if (jinode->i_transaction == transaction ||
2141            jinode->i_next_transaction == transaction)
2142                return 0;
2143
2144        spin_lock(&journal->j_list_lock);
2145
2146        if (jinode->i_transaction == transaction ||
2147            jinode->i_next_transaction == transaction)
2148                goto done;
2149
2150        /* On some different transaction's list - should be
2151         * the committing one */
2152        if (jinode->i_transaction) {
2153                J_ASSERT(jinode->i_next_transaction == NULL);
2154                J_ASSERT(jinode->i_transaction ==
2155                                        journal->j_committing_transaction);
2156                jinode->i_next_transaction = transaction;
2157                goto done;
2158        }
2159        /* Not on any transaction list... */
2160        J_ASSERT(!jinode->i_next_transaction);
2161        jinode->i_transaction = transaction;
2162        list_add(&jinode->i_list, &transaction->t_inode_list);
2163done:
2164        spin_unlock(&journal->j_list_lock);
2165
2166        return 0;
2167}
2168
2169/*
2170 * File truncate and transaction commit interact with each other in a
2171 * non-trivial way.  If a transaction writing data block A is
2172 * committing, we cannot discard the data by truncate until we have
2173 * written them.  Otherwise if we crashed after the transaction with
2174 * write has committed but before the transaction with truncate has
2175 * committed, we could see stale data in block A.  This function is a
2176 * helper to solve this problem.  It starts writeout of the truncated
2177 * part in case it is in the committing transaction.
2178 *
2179 * Filesystem code must call this function when inode is journaled in
2180 * ordered mode before truncation happens and after the inode has been
2181 * placed on orphan list with the new inode size. The second condition
2182 * avoids the race that someone writes new data and we start
2183 * committing the transaction after this function has been called but
2184 * before a transaction for truncate is started (and furthermore it
2185 * allows us to optimize the case where the addition to orphan list
2186 * happens in the same transaction as write --- we don't have to write
2187 * any data in such case).
2188 */
2189int jbd2_journal_begin_ordered_truncate(journal_t *journal,
2190                                        struct jbd2_inode *jinode,
2191                                        loff_t new_size)
2192{
2193        transaction_t *inode_trans, *commit_trans;
2194        int ret = 0;
2195
2196        /* This is a quick check to avoid locking if not necessary */
2197        if (!jinode->i_transaction)
2198                goto out;
2199        /* Locks are here just to force reading of recent values, it is
2200         * enough that the transaction was not committing before we started
2201         * a transaction adding the inode to orphan list */
2202        read_lock(&journal->j_state_lock);
2203        commit_trans = journal->j_committing_transaction;
2204        read_unlock(&journal->j_state_lock);
2205        spin_lock(&journal->j_list_lock);
2206        inode_trans = jinode->i_transaction;
2207        spin_unlock(&journal->j_list_lock);
2208        if (inode_trans == commit_trans) {
2209                ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping,
2210                        new_size, LLONG_MAX);
2211                if (ret)
2212                        jbd2_journal_abort(journal, ret);
2213        }
2214out:
2215        return ret;
2216}
2217