fs/jbd/transaction.c

   1 /*
   2  * linux/fs/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/jbd.h>
  23 #include <linux/errno.h>
  24 #include <linux/slab.h>
  25 #include <linux/timer.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/mm.h>
  28 #include <linux/highmem.h>
  29
  30 /*
  31  * get_transaction: obtain a new transaction_t object.
  32  *
  33  * Simply allocate and initialise a new transaction.  Create it in
  34  * RUNNING state and add it to the current journal (which should not
  35  * have an existing running transaction: we only make a new transaction
  36  * once we have started to commit the old one).
  37  *
  38  * Preconditions:
  39  *      The journal MUST be locked.  We don't perform atomic mallocs on the
  40  *      new transaction and we can't block without protecting against other
  41  *      processes trying to touch the journal while it is in transition.
  42  *
  43  * Called under j_state_lock
  44  */
  45
  46 static transaction_t *
  47 get_transaction(journal_t *journal, transaction_t *transaction)
  48 {
  49         transaction->t_journal = journal;
  50         transaction->t_state = T_RUNNING;
  51         transaction->t_tid = journal->j_transaction_sequence++;
  52         transaction->t_expires = jiffies + journal->j_commit_interval;
  53         INIT_LIST_HEAD(&transaction->t_jcb);
  54         spin_lock_init(&transaction->t_handle_lock);
  55         spin_lock_init(&transaction->t_jcb_lock);
  56
  57         /* Set up the commit timer for the new transaction. */
  58         journal->j_commit_timer->expires = transaction->t_expires;
  59         add_timer(journal->j_commit_timer);
  60
  61         J_ASSERT(journal->j_running_transaction == NULL);
  62         journal->j_running_transaction = transaction;
  63
  64         return transaction;
  65 }
  66
  67 /*
  68  * Handle management.
  69  *
  70  * A handle_t is an object which represents a single atomic update to a
  71  * filesystem, and which tracks all of the modifications which form part
  72  * of that one update.
  73  */
  74
  75 /*
  76  * start_this_handle: Given a handle, deal with any locking or stalling
  77  * needed to make sure that there is enough journal space for the handle
  78  * to begin.  Attach the handle to a transaction and set up the
  79  * transaction's buffer credits.
  80  */
  81
  82 static int start_this_handle(journal_t *journal, handle_t *handle)
  83 {
  84         transaction_t *transaction;
  85         int needed;
  86         int nblocks = handle->h_buffer_credits;
  87         transaction_t *new_transaction = NULL;
  88         int ret = 0;
  89
  90         if (nblocks > journal->j_max_transaction_buffers) {
  91                 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
  92                        current->comm, nblocks,
  93                        journal->j_max_transaction_buffers);
  94                 ret = -ENOSPC;
  95                 goto out;
  96         }
  97
  98 alloc_transaction:
  99         if (!journal->j_running_transaction) {
 100                 new_transaction = jbd_kmalloc(sizeof(*new_transaction),
 101                                                 GFP_NOFS);
 102                 if (!new_transaction) {
 103                         ret = -ENOMEM;
 104                         goto out;
 105                 }
 106                 memset(new_transaction, 0, sizeof(*new_transaction));
 107         }
 108
 109         jbd_debug(3, "New handle %p going live.\n", handle);
 110
 111 repeat:
 112
 113         /*
 114          * We need to hold j_state_lock until t_updates has been incremented,
 115          * for proper journal barrier handling
 116          */
 117         spin_lock(&journal->j_state_lock);
 118 repeat_locked:
 119         if (is_journal_aborted(journal) ||
 120             (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
 121                 spin_unlock(&journal->j_state_lock);
 122                 ret = -EROFS;
 123                 goto out;
 124         }
 125
 126         /* Wait on the journal's transaction barrier if necessary */
 127         if (journal->j_barrier_count) {
 128                 spin_unlock(&journal->j_state_lock);
 129                 wait_event(journal->j_wait_transaction_locked,
 130                                 journal->j_barrier_count == 0);
 131                 goto repeat;
 132         }
 133
 134         if (!journal->j_running_transaction) {
 135                 if (!new_transaction) {
 136                         spin_unlock(&journal->j_state_lock);
 137                         goto alloc_transaction;
 138                 }
 139                 get_transaction(journal, new_transaction);
 140                 new_transaction = NULL;
 141         }
 142
 143         transaction = journal->j_running_transaction;
 144
 145         /*
 146          * If the current transaction is locked down for commit, wait for the
 147          * lock to be released.
 148          */
 149         if (transaction->t_state == T_LOCKED) {
 150                 DEFINE_WAIT(wait);
 151
 152                 prepare_to_wait(&journal->j_wait_transaction_locked,
 153                                         &wait, TASK_UNINTERRUPTIBLE);
 154                 spin_unlock(&journal->j_state_lock);
 155                 schedule();
 156                 finish_wait(&journal->j_wait_transaction_locked, &wait);
 157                 goto repeat;
 158         }
 159
 160         /*
 161          * If there is not enough space left in the log to write all potential
 162          * buffers requested by this operation, we need to stall pending a log
 163          * checkpoint to free some more log space.
 164          */
 165         spin_lock(&transaction->t_handle_lock);
 166         needed = transaction->t_outstanding_credits + nblocks;
 167
 168         if (needed > journal->j_max_transaction_buffers) {
 169                 /*
 170                  * If the current transaction is already too large, then start
 171                  * to commit it: we can then go back and attach this handle to
 172                  * a new transaction.
 173                  */
 174                 DEFINE_WAIT(wait);
 175
 176                 jbd_debug(2, "Handle %p starting new commit...\n", handle);
 177                 spin_unlock(&transaction->t_handle_lock);
 178                 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
 179                                 TASK_UNINTERRUPTIBLE);
 180                 __log_start_commit(journal, transaction->t_tid);
 181                 spin_unlock(&journal->j_state_lock);
 182                 schedule();
 183                 finish_wait(&journal->j_wait_transaction_locked, &wait);
 184                 goto repeat;
 185         }
 186
 187         /*
 188          * The commit code assumes that it can get enough log space
 189          * without forcing a checkpoint.  This is *critical* for
 190          * correctness: a checkpoint of a buffer which is also
 191          * associated with a committing transaction creates a deadlock,
 192          * so commit simply cannot force through checkpoints.
 193          *
 194          * We must therefore ensure the necessary space in the journal
 195          * *before* starting to dirty potentially checkpointed buffers
 196          * in the new transaction.
 197          *
 198          * The worst part is, any transaction currently committing can
 199          * reduce the free space arbitrarily.  Be careful to account for
 200          * those buffers when checkpointing.
 201          */
 202
 203         /*
 204          * @@@ AKPM: This seems rather over-defensive.  We're giving commit
 205          * a _lot_ of headroom: 1/4 of the journal plus the size of
 206          * the committing transaction.  Really, we only need to give it
 207          * committing_transaction->t_outstanding_credits plus "enough" for
 208          * the log control blocks.
 209          * Also, this test is inconsitent with the matching one in
 210          * journal_extend().
 211          */
 212         if (__log_space_left(journal) < jbd_space_needed(journal)) {
 213                 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
 214                 spin_unlock(&transaction->t_handle_lock);
 215                 __log_wait_for_space(journal);
 216                 goto repeat_locked;
 217         }
 218
 219         /* OK, account for the buffers that this operation expects to
 220          * use and add the handle to the running transaction. */
 221
 222         handle->h_transaction = transaction;
 223         transaction->t_outstanding_credits += nblocks;
 224         transaction->t_updates++;
 225         transaction->t_handle_count++;
 226         jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
 227                   handle, nblocks, transaction->t_outstanding_credits,
 228                   __log_space_left(journal));
 229         spin_unlock(&transaction->t_handle_lock);
 230         spin_unlock(&journal->j_state_lock);
 231 out:
 232         if (new_transaction)
 233                 kfree(new_transaction);
 234         return ret;
 235 }
 236
 237 /* Allocate a new handle.  This should probably be in a slab... */
 238 static handle_t *new_handle(int nblocks)
 239 {
 240         handle_t *handle = jbd_alloc_handle(GFP_NOFS);
 241         if (!handle)
 242                 return NULL;
 243         memset(handle, 0, sizeof(*handle));
 244         handle->h_buffer_credits = nblocks;
 245         handle->h_ref = 1;
 246         INIT_LIST_HEAD(&handle->h_jcb);
 247
 248         return handle;
 249 }
 250
 251 /**
 252  * handle_t *journal_start() - Obtain a new handle.
 253  * @journal: Journal to start transaction on.
 254  * @nblocks: number of block buffer we might modify
 255  *
 256  * We make sure that the transaction can guarantee at least nblocks of
 257  * modified buffers in the log.  We block until the log can guarantee
 258  * that much space.
 259  *
 260  * This function is visible to journal users (like ext3fs), so is not
 261  * called with the journal already locked.
 262  *
 263  * Return a pointer to a newly allocated handle, or NULL on failure
 264  */
 265 handle_t *journal_start(journal_t *journal, int nblocks)
 266 {
 267         handle_t *handle = journal_current_handle();
 268         int err;
 269
 270         if (!journal)
 271                 return ERR_PTR(-EROFS);
 272
 273         if (handle) {
 274                 J_ASSERT(handle->h_transaction->t_journal == journal);
 275                 handle->h_ref++;
 276                 return handle;
 277         }
 278
 279         handle = new_handle(nblocks);
 280         if (!handle)
 281                 return ERR_PTR(-ENOMEM);
 282
 283         current->journal_info = handle;
 284
 285         err = start_this_handle(journal, handle);
 286         if (err < 0) {
 287                 jbd_free_handle(handle);
 288                 current->journal_info = NULL;
 289                 handle = ERR_PTR(err);
 290         }
 291         return handle;
 292 }
 293
 294 /**
 295  * int journal_extend() - extend buffer credits.
 296  * @handle:  handle to 'extend'
 297  * @nblocks: nr blocks to try to extend by.
 298  *
 299  * Some transactions, such as large extends and truncates, can be done
 300  * atomically all at once or in several stages.  The operation requests
 301  * a credit for a number of buffer modications in advance, but can
 302  * extend its credit if it needs more.
 303  *
 304  * journal_extend tries to give the running handle more buffer credits.
 305  * It does not guarantee that allocation - this is a best-effort only.
 306  * The calling process MUST be able to deal cleanly with a failure to
 307  * extend here.
 308  *
 309  * Return 0 on success, non-zero on failure.
 310  *
 311  * return code < 0 implies an error
 312  * return code > 0 implies normal transaction-full status.
 313  */
 314 int journal_extend(handle_t *handle, int nblocks)
 315 {
 316         transaction_t *transaction = handle->h_transaction;
 317         journal_t *journal = transaction->t_journal;
 318         int result;
 319         int wanted;
 320
 321         result = -EIO;
 322         if (is_handle_aborted(handle))
 323                 goto error_out;
 324
 325         result = 1;
 326
 327         spin_lock(&journal->j_state_lock);
 328
 329         /* Don't extend a locked-down transaction! */
 330         if (handle->h_transaction->t_state != T_RUNNING) {
 331                 jbd_debug(3, "denied handle %p %d blocks: "
 332                           "transaction not running\n", handle, nblocks);
 333                 goto error_out;
 334         }
 335
 336         spin_lock(&transaction->t_handle_lock);
 337         wanted = transaction->t_outstanding_credits + nblocks;
 338
 339         if (wanted > journal->j_max_transaction_buffers) {
 340                 jbd_debug(3, "denied handle %p %d blocks: "
 341                           "transaction too large\n", handle, nblocks);
 342                 goto unlock;
 343         }
 344
 345         if (wanted > __log_space_left(journal)) {
 346                 jbd_debug(3, "denied handle %p %d blocks: "
 347                           "insufficient log space\n", handle, nblocks);
 348                 goto unlock;
 349         }
 350
 351         handle->h_buffer_credits += nblocks;
 352         transaction->t_outstanding_credits += nblocks;
 353         result = 0;
 354
 355         jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
 356 unlock:
 357         spin_unlock(&transaction->t_handle_lock);
 358 error_out:
 359         spin_unlock(&journal->j_state_lock);
 360         return result;
 361 }
 362
 363
 364 /**
 365  * int journal_restart() - restart a handle .
 366  * @handle:  handle to restart
 367  * @nblocks: nr credits requested
 368  *
 369  * Restart a handle for a multi-transaction filesystem
 370  * operation.
 371  *
 372  * If the journal_extend() call above fails to grant new buffer credits
 373  * to a running handle, a call to journal_restart will commit the
 374  * handle's transaction so far and reattach the handle to a new
 375  * transaction capabable of guaranteeing the requested number of
 376  * credits.
 377  */
 378
 379 int journal_restart(handle_t *handle, int nblocks)
 380 {
 381         transaction_t *transaction = handle->h_transaction;
 382         journal_t *journal = transaction->t_journal;
 383         int ret;
 384
 385         /* If we've had an abort of any type, don't even think about
 386          * actually doing the restart! */
 387         if (is_handle_aborted(handle))
 388                 return 0;
 389
 390         /*
 391          * First unlink the handle from its current transaction, and start the
 392          * commit on that.
 393          */
 394         J_ASSERT(transaction->t_updates > 0);
 395         J_ASSERT(journal_current_handle() == handle);
 396
 397         spin_lock(&journal->j_state_lock);
 398         spin_lock(&transaction->t_handle_lock);
 399         transaction->t_outstanding_credits -= handle->h_buffer_credits;
 400         transaction->t_updates--;
 401
 402         if (!transaction->t_updates)
 403                 wake_up(&journal->j_wait_updates);
 404         spin_unlock(&transaction->t_handle_lock);
 405
 406         jbd_debug(2, "restarting handle %p\n", handle);
 407         __log_start_commit(journal, transaction->t_tid);
 408         spin_unlock(&journal->j_state_lock);
 409
 410         handle->h_buffer_credits = nblocks;
 411         ret = start_this_handle(journal, handle);
 412         return ret;
 413 }
 414
 415
 416 /**
 417  * void journal_lock_updates () - establish a transaction barrier.
 418  * @journal:  Journal to establish a barrier on.
 419  *
 420  * This locks out any further updates from being started, and blocks
 421  * until all existing updates have completed, returning only once the
 422  * journal is in a quiescent state with no updates running.
 423  *
 424  * The journal lock should not be held on entry.
 425  */
 426 void journal_lock_updates(journal_t *journal)
 427 {
 428         DEFINE_WAIT(wait);
 429
 430         spin_lock(&journal->j_state_lock);
 431         ++journal->j_barrier_count;
 432
 433         /* Wait until there are no running updates */
 434         while (1) {
 435                 transaction_t *transaction = journal->j_running_transaction;
 436
 437                 if (!transaction)
 438                         break;
 439
 440                 spin_lock(&transaction->t_handle_lock);
 441                 if (!transaction->t_updates) {
 442                         spin_unlock(&transaction->t_handle_lock);
 443                         break;
 444                 }
 445                 prepare_to_wait(&journal->j_wait_updates, &wait,
 446                                 TASK_UNINTERRUPTIBLE);
 447                 spin_unlock(&transaction->t_handle_lock);
 448                 spin_unlock(&journal->j_state_lock);
 449                 schedule();
 450                 finish_wait(&journal->j_wait_updates, &wait);
 451                 spin_lock(&journal->j_state_lock);
 452         }
 453         spin_unlock(&journal->j_state_lock);
 454
 455         /*
 456          * We have now established a barrier against other normal updates, but
 457          * we also need to barrier against other journal_lock_updates() calls
 458          * to make sure that we serialise special journal-locked operations
 459          * too.
 460          */
 461         down(&journal->j_barrier);
 462 }
 463
 464 /**
 465  * void journal_unlock_updates (journal_t* journal) - release barrier
 466  * @journal:  Journal to release the barrier on.
 467  *
 468  * Release a transaction barrier obtained with journal_lock_updates().
 469  *
 470  * Should be called without the journal lock held.
 471  */
 472 void journal_unlock_updates (journal_t *journal)
 473 {
 474         J_ASSERT(journal->j_barrier_count != 0);
 475
 476         up(&journal->j_barrier);
 477         spin_lock(&journal->j_state_lock);
 478         --journal->j_barrier_count;
 479         spin_unlock(&journal->j_state_lock);
 480         wake_up(&journal->j_wait_transaction_locked);
 481 }
 482
 483 /*
 484  * Report any unexpected dirty buffers which turn up.  Normally those
 485  * indicate an error, but they can occur if the user is running (say)
 486  * tune2fs to modify the live filesystem, so we need the option of
 487  * continuing as gracefully as possible.  #
 488  *
 489  * The caller should already hold the journal lock and
 490  * j_list_lock spinlock: most callers will need those anyway
 491  * in order to probe the buffer's journaling state safely.
 492  */
 493 static void jbd_unexpected_dirty_buffer(struct journal_head *jh)
 494 {
 495         struct buffer_head *bh = jh2bh(jh);
 496         int jlist;
 497
 498         if (buffer_dirty(bh)) {
 499                 /* If this buffer is one which might reasonably be dirty
 500                  * --- ie. data, or not part of this journal --- then
 501                  * we're OK to leave it alone, but otherwise we need to
 502                  * move the dirty bit to the journal's own internal
 503                  * JBDDirty bit. */
 504                 jlist = jh->b_jlist;
 505
 506                 if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
 507                     jlist == BJ_Shadow || jlist == BJ_Forget) {
 508                         if (test_clear_buffer_dirty(jh2bh(jh))) {
 509                                 set_bit(BH_JBDDirty, &jh2bh(jh)->b_state);
 510                         }
 511                 }
 512         }
 513 }
 514
 515 /*
 516  * If the buffer is already part of the current transaction, then there
 517  * is nothing we need to do.  If it is already part of a prior
 518  * transaction which we are still committing to disk, then we need to
 519  * make sure that we do not overwrite the old copy: we do copy-out to
 520  * preserve the copy going to disk.  We also account the buffer against
 521  * the handle's metadata buffer credits (unless the buffer is already
 522  * part of the transaction, that is).
 523  *
 524  */
 525 static int
 526 do_get_write_access(handle_t *handle, struct journal_head *jh,
 527                         int force_copy, int *credits)
 528 {
 529         struct buffer_head *bh;
 530         transaction_t *transaction;
 531         journal_t *journal;
 532         int error;
 533         char *frozen_buffer = NULL;
 534         int need_copy = 0;
 535
 536         if (is_handle_aborted(handle))
 537                 return -EROFS;
 538
 539         transaction = handle->h_transaction;
 540         journal = transaction->t_journal;
 541
 542         jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
 543
 544         JBUFFER_TRACE(jh, "entry");
 545 repeat:
 546         bh = jh2bh(jh);
 547
 548         /* @@@ Need to check for errors here at some point. */
 549
 550         lock_buffer(bh);
 551         jbd_lock_bh_state(bh);
 552
 553         /* We now hold the buffer lock so it is safe to query the buffer
 554          * state.  Is the buffer dirty?
 555          *
 556          * If so, there are two possibilities.  The buffer may be
 557          * non-journaled, and undergoing a quite legitimate writeback.
 558          * Otherwise, it is journaled, and we don't expect dirty buffers
 559          * in that state (the buffers should be marked JBD_Dirty
 560          * instead.)  So either the IO is being done under our own
 561          * control and this is a bug, or it's a third party IO such as
 562          * dump(8) (which may leave the buffer scheduled for read ---
 563          * ie. locked but not dirty) or tune2fs (which may actually have
 564          * the buffer dirtied, ugh.)  */
 565
 566         if (buffer_dirty(bh)) {
 567                 /*
 568                  * First question: is this buffer already part of the current
 569                  * transaction or the existing committing transaction?
 570                  */
 571                 if (jh->b_transaction) {
 572                         J_ASSERT_JH(jh,
 573                                 jh->b_transaction == transaction ||
 574                                 jh->b_transaction ==
 575                                         journal->j_committing_transaction);
 576                         if (jh->b_next_transaction)
 577                                 J_ASSERT_JH(jh, jh->b_next_transaction ==
 578                                                         transaction);
 579                         JBUFFER_TRACE(jh, "Unexpected dirty buffer");
 580                         jbd_unexpected_dirty_buffer(jh);
 581                 }
 582         }
 583
 584         unlock_buffer(bh);
 585
 586         error = -EROFS;
 587         if (is_handle_aborted(handle)) {
 588                 jbd_unlock_bh_state(bh);
 589                 goto out;
 590         }
 591         error = 0;
 592
 593         /*
 594          * The buffer is already part of this transaction if b_transaction or
 595          * b_next_transaction points to it
 596          */
 597         if (jh->b_transaction == transaction ||
 598             jh->b_next_transaction == transaction)
 599                 goto done;
 600
 601         /*
 602          * If there is already a copy-out version of this buffer, then we don't
 603          * need to make another one
 604          */
 605         if (jh->b_frozen_data) {
 606                 JBUFFER_TRACE(jh, "has frozen data");
 607                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
 608                 jh->b_next_transaction = transaction;
 609
 610                 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
 611                 handle->h_buffer_credits--;
 612                 if (credits)
 613                         (*credits)++;
 614                 goto done;
 615         }
 616
 617         /* Is there data here we need to preserve? */
 618
 619         if (jh->b_transaction && jh->b_transaction != transaction) {
 620                 JBUFFER_TRACE(jh, "owned by older transaction");
 621                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
 622                 J_ASSERT_JH(jh, jh->b_transaction ==
 623                                         journal->j_committing_transaction);
 624
 625                 /* There is one case we have to be very careful about.
 626                  * If the committing transaction is currently writing
 627                  * this buffer out to disk and has NOT made a copy-out,
 628                  * then we cannot modify the buffer contents at all
 629                  * right now.  The essence of copy-out is that it is the
 630                  * extra copy, not the primary copy, which gets
 631                  * journaled.  If the primary copy is already going to
 632                  * disk then we cannot do copy-out here. */
 633
 634                 if (jh->b_jlist == BJ_Shadow) {
 635                         wait_queue_head_t *wqh;
 636                         DEFINE_WAIT(wait);
 637
 638                         JBUFFER_TRACE(jh, "on shadow: sleep");
 639                         jbd_unlock_bh_state(bh);
 640                         /* commit wakes up all shadow buffers after IO */
 641                         wqh = bh_waitq_head(bh);
 642                         for ( ; ; ) {
 643                                 prepare_to_wait(wqh, &wait,
 644                                                 TASK_UNINTERRUPTIBLE);
 645                                 if (jh->b_jlist != BJ_Shadow)
 646                                         break;
 647                                 schedule();
 648                         }
 649                         finish_wait(wqh, &wait);
 650                         goto repeat;
 651                 }
 652
 653                 /* Only do the copy if the currently-owning transaction
 654                  * still needs it.  If it is on the Forget list, the
 655                  * committing transaction is past that stage.  The
 656                  * buffer had better remain locked during the kmalloc,
 657                  * but that should be true --- we hold the journal lock
 658                  * still and the buffer is already on the BUF_JOURNAL
 659                  * list so won't be flushed.
 660                  *
 661                  * Subtle point, though: if this is a get_undo_access,
 662                  * then we will be relying on the frozen_data to contain
 663                  * the new value of the committed_data record after the
 664                  * transaction, so we HAVE to force the frozen_data copy
 665                  * in that case. */
 666
 667                 if (jh->b_jlist != BJ_Forget || force_copy) {
 668                         JBUFFER_TRACE(jh, "generate frozen data");
 669                         if (!frozen_buffer) {
 670                                 JBUFFER_TRACE(jh, "allocate memory for buffer");
 671                                 jbd_unlock_bh_state(bh);
 672                                 frozen_buffer = jbd_kmalloc(jh2bh(jh)->b_size,
 673                                                             GFP_NOFS);
 674                                 if (!frozen_buffer) {
 675                                         printk(KERN_EMERG
 676                                                "%s: OOM for frozen_buffer\n",
 677                                                __FUNCTION__);
 678                                         JBUFFER_TRACE(jh, "oom!");
 679                                         error = -ENOMEM;
 680                                         jbd_lock_bh_state(bh);
 681                                         goto done;
 682                                 }
 683                                 goto repeat;
 684                         }
 685                         jh->b_frozen_data = frozen_buffer;
 686                         frozen_buffer = NULL;
 687                         need_copy = 1;
 688                 }
 689                 jh->b_next_transaction = transaction;
 690         }
 691
 692         J_ASSERT(handle->h_buffer_credits > 0);
 693         handle->h_buffer_credits--;
 694         if (credits)
 695                 (*credits)++;
 696
 697         /*
 698          * Finally, if the buffer is not journaled right now, we need to make
 699          * sure it doesn't get written to disk before the caller actually
 700          * commits the new data
 701          */
 702         if (!jh->b_transaction) {
 703                 JBUFFER_TRACE(jh, "no transaction");
 704                 J_ASSERT_JH(jh, !jh->b_next_transaction);
 705                 jh->b_transaction = transaction;
 706                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
 707                 spin_lock(&journal->j_list_lock);
 708                 __journal_file_buffer(jh, transaction, BJ_Reserved);
 709                 spin_unlock(&journal->j_list_lock);
 710         }
 711
 712 done:
 713         if (need_copy) {
 714                 struct page *page;
 715                 int offset;
 716                 char *source;
 717
 718                 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
 719                             "Possible IO failure.\n");
 720                 page = jh2bh(jh)->b_page;
 721                 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
 722                 source = kmap_atomic(page, KM_USER0);
 723                 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
 724                 kunmap_atomic(source, KM_USER0);
 725         }
 726         jbd_unlock_bh_state(bh);
 727
 728         /*
 729          * If we are about to journal a buffer, then any revoke pending on it is
 730          * no longer valid
 731          */
 732         journal_cancel_revoke(handle, jh);
 733
 734 out:
 735         if (frozen_buffer)
 736                 kfree(frozen_buffer);
 737
 738         JBUFFER_TRACE(jh, "exit");
 739         return error;
 740 }
 741
 742 /**
 743  * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
 744  * @handle: transaction to add buffer modifications to
 745  * @bh:     bh to be used for metadata writes
 746  *
 747  * Returns an error code or 0 on success.
 748  *
 749  * In full data journalling mode the buffer may be of type BJ_AsyncData,
 750  * because we're write()ing a buffer which is also part of a shared mapping.
 751  */
 752
 753 int journal_get_write_access(handle_t *handle,
 754                         struct buffer_head *bh, int *credits)
 755 {
 756         struct journal_head *jh = journal_add_journal_head(bh);
 757         int rc;
 758
 759         /* We do not want to get caught playing with fields which the
 760          * log thread also manipulates.  Make sure that the buffer
 761          * completes any outstanding IO before proceeding. */
 762         rc = do_get_write_access(handle, jh, 0, credits);
 763         journal_put_journal_head(jh);
 764         return rc;
 765 }
 766
 767
 768 /*
 769  * When the user wants to journal a newly created buffer_head
 770  * (ie. getblk() returned a new buffer and we are going to populate it
 771  * manually rather than reading off disk), then we need to keep the
 772  * buffer_head locked until it has been completely filled with new
 773  * data.  In this case, we should be able to make the assertion that
 774  * the bh is not already part of an existing transaction.
 775  *
 776  * The buffer should already be locked by the caller by this point.
 777  * There is no lock ranking violation: it was a newly created,
 778  * unlocked buffer beforehand. */
 779
 780 /**
 781  * int journal_get_create_access () - notify intent to use newly created bh
 782  * @handle: transaction to new buffer to
 783  * @bh: new buffer.
 784  *
 785  * Call this if you create a new bh.
 786  */
 787 int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
 788 {
 789         transaction_t *transaction = handle->h_transaction;
 790         journal_t *journal = transaction->t_journal;
 791         struct journal_head *jh = journal_add_journal_head(bh);
 792         int err;
 793
 794         jbd_debug(5, "journal_head %p\n", jh);
 795         err = -EROFS;
 796         if (is_handle_aborted(handle))
 797                 goto out;
 798         err = 0;
 799
 800         JBUFFER_TRACE(jh, "entry");
 801         /*
 802          * The buffer may already belong to this transaction due to pre-zeroing
 803          * in the filesystem's new_block code.  It may also be on the previous,
 804          * committing transaction's lists, but it HAS to be in Forget state in
 805          * that case: the transaction must have deleted the buffer for it to be
 806          * reused here.
 807          */
 808         jbd_lock_bh_state(bh);
 809         spin_lock(&journal->j_list_lock);
 810         J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
 811                 jh->b_transaction == NULL ||
 812                 (jh->b_transaction == journal->j_committing_transaction &&
 813                           jh->b_jlist == BJ_Forget)));
 814
 815         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
 816         J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
 817
 818         J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
 819         handle->h_buffer_credits--;
 820
 821         if (jh->b_transaction == NULL) {
 822                 jh->b_transaction = transaction;
 823                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
 824                 __journal_file_buffer(jh, transaction, BJ_Reserved);
 825         } else if (jh->b_transaction == journal->j_committing_transaction) {
 826                 JBUFFER_TRACE(jh, "set next transaction");
 827                 jh->b_next_transaction = transaction;
 828         }
 829         spin_unlock(&journal->j_list_lock);
 830         jbd_unlock_bh_state(bh);
 831
 832         /*
 833          * akpm: I added this.  ext3_alloc_branch can pick up new indirect
 834          * blocks which contain freed but then revoked metadata.  We need
 835          * to cancel the revoke in case we end up freeing it yet again
 836          * and the reallocating as data - this would cause a second revoke,
 837          * which hits an assertion error.
 838          */
 839         JBUFFER_TRACE(jh, "cancelling revoke");
 840         journal_cancel_revoke(handle, jh);
 841         journal_put_journal_head(jh);
 842 out:
 843         return err;
 844 }
 845
 846 /**
 847  * int journal_get_undo_access() -  Notify intent to modify metadata with
 848  *     non-rewindable consequences
 849  * @handle: transaction
 850  * @bh: buffer to undo
 851  * @credits: store the number of taken credits here (if not NULL)
 852  *
 853  * Sometimes there is a need to distinguish between metadata which has
 854  * been committed to disk and that which has not.  The ext3fs code uses
 855  * this for freeing and allocating space, we have to make sure that we
 856  * do not reuse freed space until the deallocation has been committed,
 857  * since if we overwrote that space we would make the delete
 858  * un-rewindable in case of a crash.
 859  *
 860  * To deal with that, journal_get_undo_access requests write access to a
 861  * buffer for parts of non-rewindable operations such as delete
 862  * operations on the bitmaps.  The journaling code must keep a copy of
 863  * the buffer's contents prior to the undo_access call until such time
 864  * as we know that the buffer has definitely been committed to disk.
 865  *
 866  * We never need to know which transaction the committed data is part
 867  * of, buffers touched here are guaranteed to be dirtied later and so
 868  * will be committed to a new transaction in due course, at which point
 869  * we can discard the old committed data pointer.
 870  *
 871  * Returns error number or 0 on success.
 872  */
 873 int journal_get_undo_access(handle_t *handle, struct buffer_head *bh,
 874                                 int *credits)
 875 {
 876         int err;
 877         struct journal_head *jh = journal_add_journal_head(bh);
 878         char *committed_data = NULL;
 879
 880         JBUFFER_TRACE(jh, "entry");
 881
 882         /*
 883          * Do this first --- it can drop the journal lock, so we want to
 884          * make sure that obtaining the committed_data is done
 885          * atomically wrt. completion of any outstanding commits.
 886          */
 887         err = do_get_write_access(handle, jh, 1, credits);
 888         if (err)
 889                 goto out;
 890
 891 repeat:
 892         if (!jh->b_committed_data) {
 893                 committed_data = jbd_kmalloc(jh2bh(jh)->b_size, GFP_NOFS);
 894                 if (!committed_data) {
 895                         printk(KERN_EMERG "%s: No memory for committed data\n",
 896                                 __FUNCTION__);
 897                         err = -ENOMEM;
 898                         goto out;
 899                 }
 900         }
 901
 902         jbd_lock_bh_state(bh);
 903         if (!jh->b_committed_data) {
 904                 /* Copy out the current buffer contents into the
 905                  * preserved, committed copy. */
 906                 JBUFFER_TRACE(jh, "generate b_committed data");
 907                 if (!committed_data) {
 908                         jbd_unlock_bh_state(bh);
 909                         goto repeat;
 910                 }
 911
 912                 jh->b_committed_data = committed_data;
 913                 committed_data = NULL;
 914                 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
 915         }
 916         jbd_unlock_bh_state(bh);
 917 out:
 918         journal_put_journal_head(jh);
 919         if (committed_data)
 920                 kfree(committed_data);
 921         return err;
 922 }
 923
 924 /**
 925  * int journal_dirty_data() -  mark a buffer as containing dirty data which
 926  *                             needs to be flushed before we can commit the
 927  *                             current transaction.
 928  * @handle: transaction
 929  * @bh: bufferhead to mark
 930  *
 931  * The buffer is placed on the transaction's data list and is marked as
 932  * belonging to the transaction.
 933  *
 934  * Returns error number or 0 on success.
 935  *
 936  * journal_dirty_data() can be called via page_launder->ext3_writepage
 937  * by kswapd.
 938  */
 939 int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
 940 {
 941         journal_t *journal = handle->h_transaction->t_journal;
 942         int need_brelse = 0;
 943         struct journal_head *jh;
 944
 945         if (is_handle_aborted(handle))
 946                 return 0;
 947
 948         jh = journal_add_journal_head(bh);
 949         JBUFFER_TRACE(jh, "entry");
 950
 951         /*
 952          * The buffer could *already* be dirty.  Writeout can start
 953          * at any time.
 954          */
 955         jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
 956
 957         /*
 958          * What if the buffer is already part of a running transaction?
 959          *
 960          * There are two cases:
 961          * 1) It is part of the current running transaction.  Refile it,
 962          *    just in case we have allocated it as metadata, deallocated
 963          *    it, then reallocated it as data.
 964          * 2) It is part of the previous, still-committing transaction.
 965          *    If all we want to do is to guarantee that the buffer will be
 966          *    written to disk before this new transaction commits, then
 967          *    being sure that the *previous* transaction has this same
 968          *    property is sufficient for us!  Just leave it on its old
 969          *    transaction.
 970          *
 971          * In case (2), the buffer must not already exist as metadata
 972          * --- that would violate write ordering (a transaction is free
 973          * to write its data at any point, even before the previous
 974          * committing transaction has committed).  The caller must
 975          * never, ever allow this to happen: there's nothing we can do
 976          * about it in this layer.
 977          */
 978         jbd_lock_bh_state(bh);
 979         spin_lock(&journal->j_list_lock);
 980         if (jh->b_transaction) {
 981                 JBUFFER_TRACE(jh, "has transaction");
 982                 if (jh->b_transaction != handle->h_transaction) {
 983                         JBUFFER_TRACE(jh, "belongs to older transaction");
 984                         J_ASSERT_JH(jh, jh->b_transaction ==
 985                                         journal->j_committing_transaction);
 986
 987                         /* @@@ IS THIS TRUE  ? */
 988                         /*
 989                          * Not any more.  Scenario: someone does a write()
 990                          * in data=journal mode.  The buffer's transaction has
 991                          * moved into commit.  Then someone does another
 992                          * write() to the file.  We do the frozen data copyout
 993                          * and set b_next_transaction to point to j_running_t.
 994                          * And while we're in that state, someone does a
 995                          * writepage() in an attempt to pageout the same area
 996                          * of the file via a shared mapping.  At present that
 997                          * calls journal_dirty_data(), and we get right here.
 998                          * It may be too late to journal the data.  Simply
 999                          * falling through to the next test will suffice: the
1000                          * data will be dirty and wil be checkpointed.  The
1001                          * ordering comments in the next comment block still
1002                          * apply.
1003                          */
1004                         //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
1005
1006                         /*
1007                          * If we're journalling data, and this buffer was
1008                          * subject to a write(), it could be metadata, forget
1009                          * or shadow against the committing transaction.  Now,
1010                          * someone has dirtied the same darn page via a mapping
1011                          * and it is being writepage()'d.
1012                          * We *could* just steal the page from commit, with some
1013                          * fancy locking there.  Instead, we just skip it -
1014                          * don't tie the page's buffers to the new transaction
1015                          * at all.
1016                          * Implication: if we crash before the writepage() data
1017                          * is written into the filesystem, recovery will replay
1018                          * the write() data.
1019                          */
1020                         if (jh->b_jlist != BJ_None &&
1021                                         jh->b_jlist != BJ_SyncData &&
1022                                         jh->b_jlist != BJ_Locked) {
1023                                 JBUFFER_TRACE(jh, "Not stealing");
1024                                 goto no_journal;
1025                         }
1026
1027                         /*
1028                          * This buffer may be undergoing writeout in commit.  We
1029                          * can't return from here and let the caller dirty it
1030                          * again because that can cause the write-out loop in
1031                          * commit to never terminate.
1032                          */
1033                         if (buffer_dirty(bh)) {
1034                                 get_bh(bh);
1035                                 spin_unlock(&journal->j_list_lock);
1036                                 jbd_unlock_bh_state(bh);
1037                                 need_brelse = 1;
1038                                 sync_dirty_buffer(bh);
1039                                 jbd_lock_bh_state(bh);
1040                                 spin_lock(&journal->j_list_lock);
1041                                 /* The buffer may become locked again at any
1042                                    time if it is redirtied */
1043                         }
1044
1045                         /* journal_clean_data_list() may have got there first */
1046                         if (jh->b_transaction != NULL) {
1047                                 JBUFFER_TRACE(jh, "unfile from commit");
1048                                 __journal_unfile_buffer(jh);
1049                         }
1050                         /* The buffer will be refiled below */
1051
1052                 }
1053                 /*
1054                  * Special case --- the buffer might actually have been
1055                  * allocated and then immediately deallocated in the previous,
1056                  * committing transaction, so might still be left on that
1057                  * transaction's metadata lists.
1058                  */
1059                 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
1060                         JBUFFER_TRACE(jh, "not on correct data list: unfile");
1061                         J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
1062                         __journal_unfile_buffer(jh);
1063                         JBUFFER_TRACE(jh, "file as data");
1064                         __journal_file_buffer(jh, handle->h_transaction,
1065                                                 BJ_SyncData);
1066                 }
1067         } else {
1068                 JBUFFER_TRACE(jh, "not on a transaction");
1069                 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
1070         }
1071 no_journal:
1072         spin_unlock(&journal->j_list_lock);
1073         jbd_unlock_bh_state(bh);
1074         if (need_brelse) {
1075                 BUFFER_TRACE(bh, "brelse");
1076                 __brelse(bh);
1077         }
1078         JBUFFER_TRACE(jh, "exit");
1079         journal_put_journal_head(jh);
1080         return 0;
1081 }
1082
1083 /**
1084  * int journal_dirty_metadata() -  mark a buffer as containing dirty metadata
1085  * @handle: transaction to add buffer to.
1086  * @bh: buffer to mark
1087  *
1088  * mark dirty metadata which needs to be journaled as part of the current
1089  * transaction.
1090  *
1091  * The buffer is placed on the transaction's metadata list and is marked
1092  * as belonging to the transaction.
1093  *
1094  * Returns error number or 0 on success.
1095  *
1096  * Special care needs to be taken if the buffer already belongs to the
1097  * current committing transaction (in which case we should have frozen
1098  * data present for that commit).  In that case, we don't relink the
1099  * buffer: that only gets done when the old transaction finally
1100  * completes its commit.
1101  */
1102 int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
1103 {
1104         transaction_t *transaction = handle->h_transaction;
1105         journal_t *journal = transaction->t_journal;
1106         struct journal_head *jh = bh2jh(bh);
1107
1108         jbd_debug(5, "journal_head %p\n", jh);
1109         JBUFFER_TRACE(jh, "entry");
1110         if (is_handle_aborted(handle))
1111                 goto out;
1112
1113         jbd_lock_bh_state(bh);
1114
1115         /*
1116          * fastpath, to avoid expensive locking.  If this buffer is already
1117          * on the running transaction's metadata list there is nothing to do.
1118          * Nobody can take it off again because there is a handle open.
1119          * I _think_ we're OK here with SMP barriers - a mistaken decision will
1120          * result in this test being false, so we go in and take the locks.
1121          */
1122         if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
1123                 JBUFFER_TRACE(jh, "fastpath");
1124                 J_ASSERT_JH(jh, jh->b_transaction ==
1125                                         journal->j_running_transaction);
1126                 goto out_unlock_bh;
1127         }
1128
1129         set_buffer_jbddirty(bh);
1130
1131         /*
1132          * Metadata already on the current transaction list doesn't
1133          * need to be filed.  Metadata on another transaction's list must
1134          * be committing, and will be refiled once the commit completes:
1135          * leave it alone for now.
1136          */
1137         if (jh->b_transaction != transaction) {
1138                 JBUFFER_TRACE(jh, "already on other transaction");
1139                 J_ASSERT_JH(jh, jh->b_transaction ==
1140                                         journal->j_committing_transaction);
1141                 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
1142                 /* And this case is illegal: we can't reuse another
1143                  * transaction's data buffer, ever. */
1144                 goto out_unlock_bh;
1145         }
1146
1147         /* That test should have eliminated the following case: */
1148         J_ASSERT_JH(jh, jh->b_frozen_data == 0);
1149
1150         JBUFFER_TRACE(jh, "file as BJ_Metadata");
1151         spin_lock(&journal->j_list_lock);
1152         __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
1153         spin_unlock(&journal->j_list_lock);
1154 out_unlock_bh:
1155         jbd_unlock_bh_state(bh);
1156 out:
1157         JBUFFER_TRACE(jh, "exit");
1158         return 0;
1159 }
1160
1161 /*
1162  * journal_release_buffer: undo a get_write_access without any buffer
1163  * updates, if the update decided in the end that it didn't need access.
1164  *
1165  * The caller passes in the number of credits which should be put back for
1166  * this buffer (zero or one).
1167  *
1168  * We leave the buffer attached to t_reserved_list because even though this
1169  * handle doesn't want it, some other concurrent handle may want to journal
1170  * this buffer.  If that handle is curently in between get_write_access() and
1171  * journal_dirty_metadata() then it expects the buffer to be reserved.  If
1172  * we were to rip it off t_reserved_list here, the other handle will explode
1173  * when journal_dirty_metadata is presented with a non-reserved buffer.
1174  *
1175  * If nobody really wants to journal this buffer then it will be thrown
1176  * away at the start of commit.
1177  */
1178 void
1179 journal_release_buffer(handle_t *handle, struct buffer_head *bh, int credits)
1180 {
1181         BUFFER_TRACE(bh, "entry");
1182         handle->h_buffer_credits += credits;
1183 }
1184
1185 /**
1186  * void journal_forget() - bforget() for potentially-journaled buffers.
1187  * @handle: transaction handle
1188  * @bh:     bh to 'forget'
1189  *
1190  * We can only do the bforget if there are no commits pending against the
1191  * buffer.  If the buffer is dirty in the current running transaction we
1192  * can safely unlink it.
1193  *
1194  * bh may not be a journalled buffer at all - it may be a non-JBD
1195  * buffer which came off the hashtable.  Check for this.
1196  *
1197  * Decrements bh->b_count by one.
1198  *
1199  * Allow this call even if the handle has aborted --- it may be part of
1200  * the caller's cleanup after an abort.
1201  */
1202 void journal_forget(handle_t *handle, struct buffer_head *bh)
1203 {
1204         transaction_t *transaction = handle->h_transaction;
1205         journal_t *journal = transaction->t_journal;
1206         struct journal_head *jh;
1207
1208         BUFFER_TRACE(bh, "entry");
1209
1210         jbd_lock_bh_state(bh);
1211         spin_lock(&journal->j_list_lock);
1212
1213         if (!buffer_jbd(bh))
1214                 goto not_jbd;
1215         jh = bh2jh(bh);
1216
1217         if (jh->b_transaction == handle->h_transaction) {
1218                 J_ASSERT_JH(jh, !jh->b_frozen_data);
1219
1220                 /* If we are forgetting a buffer which is already part
1221                  * of this transaction, then we can just drop it from
1222                  * the transaction immediately. */
1223                 clear_buffer_dirty(bh);
1224                 clear_buffer_jbddirty(bh);
1225
1226                 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
1227                 J_ASSERT_JH(jh, !jh->b_committed_data);
1228
1229                 __journal_unfile_buffer(jh);
1230
1231                 /*
1232                  * We are no longer going to journal this buffer.
1233                  * However, the commit of this transaction is still
1234                  * important to the buffer: the delete that we are now
1235                  * processing might obsolete an old log entry, so by
1236                  * committing, we can satisfy the buffer's checkpoint.
1237                  *
1238                  * So, if we have a checkpoint on the buffer, we should
1239                  * now refile the buffer on our BJ_Forget list so that
1240                  * we know to remove the checkpoint after we commit.
1241                  */
1242
1243                 if (jh->b_cp_transaction) {
1244                         __journal_file_buffer(jh, transaction, BJ_Forget);
1245                 } else {
1246                         journal_remove_journal_head(bh);
1247                         __brelse(bh);
1248                         if (!buffer_jbd(bh)) {
1249                                 spin_unlock(&journal->j_list_lock);
1250                                 jbd_unlock_bh_state(bh);
1251                                 __bforget(bh);
1252                                 return;
1253                         }
1254                 }
1255         } else if (jh->b_transaction) {
1256                 J_ASSERT_JH(jh, (jh->b_transaction ==
1257                                  journal->j_committing_transaction));
1258                 /* However, if the buffer is still owned by a prior
1259                  * (committing) transaction, we can't drop it yet... */
1260                 JBUFFER_TRACE(jh, "belongs to older transaction");
1261                 /* ... but we CAN drop it from the new transaction if we
1262                  * have also modified it since the original commit. */
1263
1264                 if (jh->b_next_transaction) {
1265                         J_ASSERT(jh->b_next_transaction == transaction);
1266                         jh->b_next_transaction = NULL;
1267                 }
1268         }
1269
1270 not_jbd:
1271         spin_unlock(&journal->j_list_lock);
1272         jbd_unlock_bh_state(bh);
1273         __brelse(bh);
1274         return;
1275 }
1276
1277 /**
1278  * void journal_callback_set() -  Register a callback function for this handle.
1279  * @handle: handle to attach the callback to.
1280  * @func: function to callback.
1281  * @jcb:  structure with additional information required by func() , and
1282  *        some space for jbd internal information.
1283  *
1284  * The function will be
1285  * called when the transaction that this handle is part of has been
1286  * committed to disk with the original callback data struct and the
1287  * error status of the journal as parameters.  There is no guarantee of
1288  * ordering between handles within a single transaction, nor between
1289  * callbacks registered on the same handle.
1290  *
1291  * The caller is responsible for allocating the journal_callback struct.
1292  * This is to allow the caller to add as much extra data to the callback
1293  * as needed, but reduce the overhead of multiple allocations.  The caller
1294  * allocated struct must start with a struct journal_callback at offset 0,
1295  * and has the caller-specific data afterwards.
1296  */
1297 void journal_callback_set(handle_t *handle,
1298                         void (*func)(struct journal_callback *jcb, int error),
1299                         struct journal_callback *jcb)
1300 {
1301         spin_lock(&handle->h_transaction->t_jcb_lock);
1302         list_add_tail(&jcb->jcb_list, &handle->h_jcb);
1303         spin_unlock(&handle->h_transaction->t_jcb_lock);
1304         jcb->jcb_func = func;
1305 }
1306
1307 /**
1308  * int journal_stop() - complete a transaction
1309  * @handle: tranaction to complete.
1310  *
1311  * All done for a particular handle.
1312  *
1313  * There is not much action needed here.  We just return any remaining
1314  * buffer credits to the transaction and remove the handle.  The only
1315  * complication is that we need to start a commit operation if the
1316  * filesystem is marked for synchronous update.
1317  *
1318  * journal_stop itself will not usually return an error, but it may
1319  * do so in unusual circumstances.  In particular, expect it to
1320  * return -EIO if a journal_abort has been executed since the
1321  * transaction began.
1322  */
1323 int journal_stop(handle_t *handle)
1324 {
1325         transaction_t *transaction = handle->h_transaction;
1326         journal_t *journal = transaction->t_journal;
1327         int old_handle_count, err;
1328
1329         J_ASSERT(transaction->t_updates > 0);
1330         J_ASSERT(journal_current_handle() == handle);
1331
1332         if (is_handle_aborted(handle))
1333                 err = -EIO;
1334         else
1335                 err = 0;
1336
1337         if (--handle->h_ref > 0) {
1338                 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
1339                           handle->h_ref);
1340                 return err;
1341         }
1342
1343         jbd_debug(4, "Handle %p going down\n", handle);
1344
1345         /*
1346          * Implement synchronous transaction batching.  If the handle
1347          * was synchronous, don't force a commit immediately.  Let's
1348          * yield and let another thread piggyback onto this transaction.
1349          * Keep doing that while new threads continue to arrive.
1350          * It doesn't cost much - we're about to run a commit and sleep
1351          * on IO anyway.  Speeds up many-threaded, many-dir operations
1352          * by 30x or more...
1353          */
1354         if (handle->h_sync) {
1355                 do {
1356                         old_handle_count = transaction->t_handle_count;
1357                         set_current_state(TASK_UNINTERRUPTIBLE);
1358                         schedule_timeout(1);
1359                 } while (old_handle_count != transaction->t_handle_count);
1360         }
1361
1362         current->journal_info = NULL;
1363         spin_lock(&journal->j_state_lock);
1364         spin_lock(&transaction->t_handle_lock);
1365         transaction->t_outstanding_credits -= handle->h_buffer_credits;
1366         transaction->t_updates--;
1367         if (!transaction->t_updates) {
1368                 wake_up(&journal->j_wait_updates);
1369                 if (journal->j_barrier_count)
1370                         wake_up(&journal->j_wait_transaction_locked);
1371         }
1372
1373         /* Move callbacks from the handle to the transaction. */
1374         spin_lock(&transaction->t_jcb_lock);
1375         list_splice(&handle->h_jcb, &transaction->t_jcb);
1376         spin_unlock(&transaction->t_jcb_lock);
1377
1378         /*
1379          * If the handle is marked SYNC, we need to set another commit
1380          * going!  We also want to force a commit if the current
1381          * transaction is occupying too much of the log, or if the
1382          * transaction is too old now.
1383          */
1384         if (handle->h_sync ||
1385                         transaction->t_outstanding_credits >
1386                                 journal->j_max_transaction_buffers ||
1387                         time_after_eq(jiffies, transaction->t_expires)) {
1388                 /* Do this even for aborted journals: an abort still
1389                  * completes the commit thread, it just doesn't write
1390                  * anything to disk. */
1391                 tid_t tid = transaction->t_tid;
1392
1393                 spin_unlock(&transaction->t_handle_lock);
1394                 jbd_debug(2, "transaction too old, requesting commit for "
1395                                         "handle %p\n", handle);
1396                 /* This is non-blocking */
1397                 __log_start_commit(journal, transaction->t_tid);
1398                 spin_unlock(&journal->j_state_lock);
1399
1400                 /*
1401                  * Special case: JFS_SYNC synchronous updates require us
1402                  * to wait for the commit to complete.
1403                  */
1404                 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
1405                         err = log_wait_commit(journal, tid);
1406         } else {
1407                 spin_unlock(&transaction->t_handle_lock);
1408                 spin_unlock(&journal->j_state_lock);
1409         }
1410
1411         jbd_free_handle(handle);
1412         return err;
1413 }
1414
1415 /**int journal_force_commit() - force any uncommitted transactions
1416  * @journal: journal to force
1417  *
1418  * For synchronous operations: force any uncommitted transactions
1419  * to disk.  May seem kludgy, but it reuses all the handle batching
1420  * code in a very simple manner.
1421  */
1422 int journal_force_commit(journal_t *journal)
1423 {
1424         handle_t *handle;
1425         int ret;
1426
1427         handle = journal_start(journal, 1);
1428         if (IS_ERR(handle)) {
1429                 ret = PTR_ERR(handle);
1430         } else {
1431                 handle->h_sync = 1;
1432                 ret = journal_stop(handle);
1433         }
1434         return ret;
1435 }
1436
1437 /*
1438  *
1439  * List management code snippets: various functions for manipulating the
1440  * transaction buffer lists.
1441  *
1442  */
1443
1444 /*
1445  * Append a buffer to a transaction list, given the transaction's list head
1446  * pointer.
1447  *
1448  * j_list_lock is held.
1449  *
1450  * jbd_lock_bh_state(jh2bh(jh)) is held.
1451  */
1452
1453 static inline void
1454 __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
1455 {
1456         if (!*list) {
1457                 jh->b_tnext = jh->b_tprev = jh;
1458                 *list = jh;
1459         } else {
1460                 /* Insert at the tail of the list to preserve order */
1461                 struct journal_head *first = *list, *last = first->b_tprev;
1462                 jh->b_tprev = last;
1463                 jh->b_tnext = first;
1464                 last->b_tnext = first->b_tprev = jh;
1465         }
1466 }
1467
1468 /*
1469  * Remove a buffer from a transaction list, given the transaction's list
1470  * head pointer.
1471  *
1472  * Called with j_list_lock held, and the journal may not be locked.
1473  *
1474  * jbd_lock_bh_state(jh2bh(jh)) is held.
1475  */
1476
1477 static inline void
1478 __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
1479 {
1480         if (*list == jh) {
1481                 *list = jh->b_tnext;
1482                 if (*list == jh)
1483                         *list = 0;
1484         }
1485         jh->b_tprev->b_tnext = jh->b_tnext;
1486         jh->b_tnext->b_tprev = jh->b_tprev;
1487 }
1488
1489 /*
1490  * Remove a buffer from the appropriate transaction list.
1491  *
1492  * Note that this function can *change* the value of
1493  * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
1494  * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list.  If the caller
1495  * is holding onto a copy of one of thee pointers, it could go bad.
1496  * Generally the caller needs to re-read the pointer from the transaction_t.
1497  *
1498  * Called under j_list_lock.  The journal may not be locked.
1499  */
1500 void __journal_unfile_buffer(struct journal_head *jh)
1501 {
1502         struct journal_head **list = 0;
1503         transaction_t *transaction;
1504         struct buffer_head *bh = jh2bh(jh);
1505
1506         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1507         transaction = jh->b_transaction;
1508         if (transaction)
1509                 assert_spin_locked(&transaction->t_journal->j_list_lock);
1510
1511         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1512         if (jh->b_jlist != BJ_None)
1513                 J_ASSERT_JH(jh, transaction != 0);
1514
1515         switch (jh->b_jlist) {
1516         case BJ_None:
1517                 goto out;
1518         case BJ_SyncData:
1519                 list = &transaction->t_sync_datalist;
1520                 break;
1521         case BJ_Metadata:
1522                 transaction->t_nr_buffers--;
1523                 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
1524                 list = &transaction->t_buffers;
1525                 break;
1526         case BJ_Forget:
1527                 list = &transaction->t_forget;
1528                 break;
1529         case BJ_IO:
1530                 list = &transaction->t_iobuf_list;
1531                 break;
1532         case BJ_Shadow:
1533                 list = &transaction->t_shadow_list;
1534                 break;
1535         case BJ_LogCtl:
1536                 list = &transaction->t_log_list;
1537                 break;
1538         case BJ_Reserved:
1539                 list = &transaction->t_reserved_list;
1540                 break;
1541         case BJ_Locked:
1542                 list = &transaction->t_locked_list;
1543                 break;
1544         }
1545
1546         __blist_del_buffer(list, jh);
1547         jh->b_jlist = BJ_None;
1548         if (test_clear_buffer_jbddirty(bh))
1549                 mark_buffer_dirty(bh);  /* Expose it to the VM */
1550 out:
1551         jh->b_transaction = NULL;
1552 }
1553
1554 void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
1555 {
1556         jbd_lock_bh_state(jh2bh(jh));
1557         spin_lock(&journal->j_list_lock);
1558         __journal_unfile_buffer(jh);
1559         spin_unlock(&journal->j_list_lock);
1560         jbd_unlock_bh_state(jh2bh(jh));
1561 }
1562
1563 /*
1564  * Called from journal_try_to_free_buffers().
1565  *
1566  * Called under jbd_lock_bh_state(bh)
1567  */
1568 static void
1569 __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
1570 {
1571         struct journal_head *jh;
1572
1573         jh = bh2jh(bh);
1574
1575         if (buffer_locked(bh) || buffer_dirty(bh))
1576                 goto out;
1577
1578         if (jh->b_next_transaction != 0)
1579                 goto out;
1580
1581         spin_lock(&journal->j_list_lock);
1582         if (jh->b_transaction != 0 && jh->b_cp_transaction == 0) {
1583                 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
1584                         /* A written-back ordered data buffer */
1585                         JBUFFER_TRACE(jh, "release data");
1586                         __journal_unfile_buffer(jh);
1587                         journal_remove_journal_head(bh);
1588                         __brelse(bh);
1589                 }
1590         } else if (jh->b_cp_transaction != 0 && jh->b_transaction == 0) {
1591                 /* written-back checkpointed metadata buffer */
1592                 if (jh->b_jlist == BJ_None) {
1593                         JBUFFER_TRACE(jh, "remove from checkpoint list");
1594                         __journal_remove_checkpoint(jh);
1595                         journal_remove_journal_head(bh);
1596                         __brelse(bh);
1597                 }
1598         }
1599         spin_unlock(&journal->j_list_lock);
1600 out:
1601         return;
1602 }
1603
1604
1605 /**
1606  * int journal_try_to_free_buffers() - try to free page buffers.
1607  * @journal: journal for operation
1608  * @page: to try and free
1609  * @gfp_mask: 'IO' mode for try_to_free_buffers()
1610  *
1611  *
1612  * For all the buffers on this page,
1613  * if they are fully written out ordered data, move them onto BUF_CLEAN
1614  * so try_to_free_buffers() can reap them.
1615  *
1616  * This function returns non-zero if we wish try_to_free_buffers()
1617  * to be called. We do this if the page is releasable by try_to_free_buffers().
1618  * We also do it if the page has locked or dirty buffers and the caller wants
1619  * us to perform sync or async writeout.
1620  *
1621  * This complicates JBD locking somewhat.  We aren't protected by the
1622  * BKL here.  We wish to remove the buffer from its committing or
1623  * running transaction's ->t_datalist via __journal_unfile_buffer.
1624  *
1625  * This may *change* the value of transaction_t->t_datalist, so anyone
1626  * who looks at t_datalist needs to lock against this function.
1627  *
1628  * Even worse, someone may be doing a journal_dirty_data on this
1629  * buffer.  So we need to lock against that.  journal_dirty_data()
1630  * will come out of the lock with the buffer dirty, which makes it
1631  * ineligible for release here.
1632  *
1633  * Who else is affected by this?  hmm...  Really the only contender
1634  * is do_get_write_access() - it could be looking at the buffer while
1635  * journal_try_to_free_buffer() is changing its state.  But that
1636  * cannot happen because we never reallocate freed data as metadata
1637  * while the data is part of a transaction.  Yes?
1638  */
1639 int journal_try_to_free_buffers(journal_t *journal,
1640                                 struct page *page, int unused_gfp_mask)
1641 {
1642         struct buffer_head *head;
1643         struct buffer_head *bh;
1644         int ret = 0;
1645
1646         J_ASSERT(PageLocked(page));
1647
1648         head = page_buffers(page);
1649         bh = head;
1650         do {
1651                 struct journal_head *jh;
1652
1653                 /*
1654                  * We take our own ref against the journal_head here to avoid
1655                  * having to add tons of locking around each instance of
1656                  * journal_remove_journal_head() and journal_put_journal_head().
1657                  */
1658                 jh = journal_grab_journal_head(bh);
1659                 if (!jh)
1660                         continue;
1661
1662                 jbd_lock_bh_state(bh);
1663                 __journal_try_to_free_buffer(journal, bh);
1664                 journal_put_journal_head(jh);
1665                 jbd_unlock_bh_state(bh);
1666                 if (buffer_jbd(bh))
1667                         goto busy;
1668         } while ((bh = bh->b_this_page) != head);
1669         ret = try_to_free_buffers(page);
1670 busy:
1671         return ret;
1672 }
1673
1674 /*
1675  * This buffer is no longer needed.  If it is on an older transaction's
1676  * checkpoint list we need to record it on this transaction's forget list
1677  * to pin this buffer (and hence its checkpointing transaction) down until
1678  * this transaction commits.  If the buffer isn't on a checkpoint list, we
1679  * release it.
1680  * Returns non-zero if JBD no longer has an interest in the buffer.
1681  *
1682  * Called under j_list_lock.
1683  *
1684  * Called under jbd_lock_bh_state(bh).
1685  */
1686 static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
1687 {
1688         int may_free = 1;
1689         struct buffer_head *bh = jh2bh(jh);
1690
1691         __journal_unfile_buffer(jh);
1692
1693         if (jh->b_cp_transaction) {
1694                 JBUFFER_TRACE(jh, "on running+cp transaction");
1695                 __journal_file_buffer(jh, transaction, BJ_Forget);
1696                 clear_buffer_jbddirty(bh);
1697                 may_free = 0;
1698         } else {
1699                 JBUFFER_TRACE(jh, "on running transaction");
1700                 journal_remove_journal_head(bh);
1701                 __brelse(bh);
1702         }
1703         return may_free;
1704 }
1705
1706 /*
1707  * journal_invalidatepage
1708  *
1709  * This code is tricky.  It has a number of cases to deal with.
1710  *
1711  * There are two invariants which this code relies on:
1712  *
1713  * i_size must be updated on disk before we start calling invalidatepage on the
1714  * data.
1715  *
1716  *  This is done in ext3 by defining an ext3_setattr method which
1717  *  updates i_size before truncate gets going.  By maintaining this
1718  *  invariant, we can be sure that it is safe to throw away any buffers
1719  *  attached to the current transaction: once the transaction commits,
1720  *  we know that the data will not be needed.
1721  *
1722  *  Note however that we can *not* throw away data belonging to the
1723  *  previous, committing transaction!
1724  *
1725  * Any disk blocks which *are* part of the previous, committing
1726  * transaction (and which therefore cannot be discarded immediately) are
1727  * not going to be reused in the new running transaction
1728  *
1729  *  The bitmap committed_data images guarantee this: any block which is
1730  *  allocated in one transaction and removed in the next will be marked
1731  *  as in-use in the committed_data bitmap, so cannot be reused until
1732  *  the next transaction to delete the block commits.  This means that
1733  *  leaving committing buffers dirty is quite safe: the disk blocks
1734  *  cannot be reallocated to a different file and so buffer aliasing is
1735  *  not possible.
1736  *
1737  *
1738  * The above applies mainly to ordered data mode.  In writeback mode we
1739  * don't make guarantees about the order in which data hits disk --- in
1740  * particular we don't guarantee that new dirty data is flushed before
1741  * transaction commit --- so it is always safe just to discard data
1742  * immediately in that mode.  --sct
1743  */
1744
1745 /*
1746  * The journal_unmap_buffer helper function returns zero if the buffer
1747  * concerned remains pinned as an anonymous buffer belonging to an older
1748  * transaction.
1749  *
1750  * We're outside-transaction here.  Either or both of j_running_transaction
1751  * and j_committing_transaction may be NULL.
1752  */
1753 static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
1754 {
1755         transaction_t *transaction;
1756         struct journal_head *jh;
1757         int may_free = 1;
1758         int ret;
1759
1760         BUFFER_TRACE(bh, "entry");
1761
1762         /*
1763          * It is safe to proceed here without the j_list_lock because the
1764          * buffers cannot be stolen by try_to_free_buffers as long as we are
1765          * holding the page lock. --sct
1766          */
1767
1768         if (!buffer_jbd(bh))
1769                 goto zap_buffer_unlocked;
1770
1771         spin_lock(&journal->j_state_lock);
1772         jbd_lock_bh_state(bh);
1773         spin_lock(&journal->j_list_lock);
1774
1775         /*
1776          * Now we have the locks, check again to see whether kjournald has
1777          * taken the buffer off the transaction.
1778          */
1779         if (!buffer_jbd(bh))
1780                 goto zap_buffer;
1781
1782         jh = bh2jh(bh);
1783         transaction = jh->b_transaction;
1784         if (transaction == NULL) {
1785                 /* First case: not on any transaction.  If it
1786                  * has no checkpoint link, then we can zap it:
1787                  * it's a writeback-mode buffer so we don't care
1788                  * if it hits disk safely. */
1789                 if (!jh->b_cp_transaction) {
1790                         JBUFFER_TRACE(jh, "not on any transaction: zap");
1791                         goto zap_buffer;
1792                 }
1793
1794                 if (!buffer_dirty(bh)) {
1795                         /* bdflush has written it.  We can drop it now */
1796                         goto zap_buffer;
1797                 }
1798
1799                 /* OK, it must be in the journal but still not
1800                  * written fully to disk: it's metadata or
1801                  * journaled data... */
1802
1803                 if (journal->j_running_transaction) {
1804                         /* ... and once the current transaction has
1805                          * committed, the buffer won't be needed any
1806                          * longer. */
1807                         JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
1808                         ret = __dispose_buffer(jh,
1809                                         journal->j_running_transaction);
1810                         spin_unlock(&journal->j_list_lock);
1811                         jbd_unlock_bh_state(bh);
1812                         spin_unlock(&journal->j_state_lock);
1813                         return ret;
1814                 } else {
1815                         /* There is no currently-running transaction. So the
1816                          * orphan record which we wrote for this file must have
1817                          * passed into commit.  We must attach this buffer to
1818                          * the committing transaction, if it exists. */
1819                         if (journal->j_committing_transaction) {
1820                                 JBUFFER_TRACE(jh, "give to committing trans");
1821                                 ret = __dispose_buffer(jh,
1822                                         journal->j_committing_transaction);
1823                                 spin_unlock(&journal->j_list_lock);
1824                                 jbd_unlock_bh_state(bh);
1825                                 spin_unlock(&journal->j_state_lock);
1826                                 return ret;
1827                         } else {
1828                                 /* The orphan record's transaction has
1829                                  * committed.  We can cleanse this buffer */
1830                                 clear_buffer_jbddirty(bh);
1831                                 goto zap_buffer;
1832                         }
1833                 }
1834         } else if (transaction == journal->j_committing_transaction) {
1835                 /* If it is committing, we simply cannot touch it.  We
1836                  * can remove it's next_transaction pointer from the
1837                  * running transaction if that is set, but nothing
1838                  * else. */
1839                 JBUFFER_TRACE(jh, "on committing transaction");
1840                 set_buffer_freed(bh);
1841                 if (jh->b_next_transaction) {
1842                         J_ASSERT(jh->b_next_transaction ==
1843                                         journal->j_running_transaction);
1844                         jh->b_next_transaction = NULL;
1845                 }
1846                 spin_unlock(&journal->j_list_lock);
1847                 jbd_unlock_bh_state(bh);
1848                 spin_unlock(&journal->j_state_lock);
1849                 return 0;
1850         } else {
1851                 /* Good, the buffer belongs to the running transaction.
1852                  * We are writing our own transaction's data, not any
1853                  * previous one's, so it is safe to throw it away
1854                  * (remember that we expect the filesystem to have set
1855                  * i_size already for this truncate so recovery will not
1856                  * expose the disk blocks we are discarding here.) */
1857                 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
1858                 may_free = __dispose_buffer(jh, transaction);
1859         }
1860
1861 zap_buffer:
1862         spin_unlock(&journal->j_list_lock);
1863         jbd_unlock_bh_state(bh);
1864         spin_unlock(&journal->j_state_lock);
1865 zap_buffer_unlocked:
1866         clear_buffer_dirty(bh);
1867         J_ASSERT_BH(bh, !buffer_jbddirty(bh));
1868         clear_buffer_mapped(bh);
1869         clear_buffer_req(bh);
1870         clear_buffer_new(bh);
1871         bh->b_bdev = NULL;
1872         return may_free;
1873 }
1874
1875 /**
1876  * int journal_invalidatepage()
1877  * @journal: journal to use for flush...
1878  * @page:    page to flush
1879  * @offset:  length of page to invalidate.
1880  *
1881  * Reap page buffers containing data after offset in page.
1882  *
1883  * Return non-zero if the page's buffers were successfully reaped.
1884  */
1885 int journal_invalidatepage(journal_t *journal,
1886                       struct page *page,
1887                       unsigned long offset)
1888 {
1889         struct buffer_head *head, *bh, *next;
1890         unsigned int curr_off = 0;
1891         int may_free = 1;
1892
1893         if (!PageLocked(page))
1894                 BUG();
1895         if (!page_has_buffers(page))
1896                 return 1;
1897
1898         /* We will potentially be playing with lists other than just the
1899          * data lists (especially for journaled data mode), so be
1900          * cautious in our locking. */
1901
1902         head = bh = page_buffers(page);
1903         do {
1904                 unsigned int next_off = curr_off + bh->b_size;
1905                 next = bh->b_this_page;
1906
1907                 /* AKPM: doing lock_buffer here may be overly paranoid */
1908                 if (offset <= curr_off) {
1909                         /* This block is wholly outside the truncation point */
1910                         lock_buffer(bh);
1911                         may_free &= journal_unmap_buffer(journal, bh);
1912                         unlock_buffer(bh);
1913                 }
1914                 curr_off = next_off;
1915                 bh = next;
1916
1917         } while (bh != head);
1918
1919         if (!offset) {
1920                 if (!may_free || !try_to_free_buffers(page))
1921                         return 0;
1922                 J_ASSERT(!page_has_buffers(page));
1923         }
1924         return 1;
1925 }
1926
1927 /*
1928  * File a buffer on the given transaction list.
1929  */
1930 void __journal_file_buffer(struct journal_head *jh,
1931                         transaction_t *transaction, int jlist)
1932 {
1933         struct journal_head **list = 0;
1934         int was_dirty = 0;
1935         struct buffer_head *bh = jh2bh(jh);
1936
1937         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
1938         assert_spin_locked(&transaction->t_journal->j_list_lock);
1939
1940         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
1941         J_ASSERT_JH(jh, jh->b_transaction == transaction ||
1942                                 jh->b_transaction == 0);
1943
1944         if (jh->b_transaction && jh->b_jlist == jlist)
1945                 return;
1946
1947         /* The following list of buffer states needs to be consistent
1948          * with __jbd_unexpected_dirty_buffer()'s handling of dirty
1949          * state. */
1950
1951         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
1952             jlist == BJ_Shadow || jlist == BJ_Forget) {
1953                 if (test_clear_buffer_dirty(bh) ||
1954                     test_clear_buffer_jbddirty(bh))
1955                         was_dirty = 1;
1956         }
1957
1958         if (jh->b_transaction)
1959                 __journal_unfile_buffer(jh);
1960         jh->b_transaction = transaction;
1961
1962         switch (jlist) {
1963         case BJ_None:
1964                 J_ASSERT_JH(jh, !jh->b_committed_data);
1965                 J_ASSERT_JH(jh, !jh->b_frozen_data);
1966                 return;
1967         case BJ_SyncData:
1968                 list = &transaction->t_sync_datalist;
1969                 break;
1970         case BJ_Metadata:
1971                 transaction->t_nr_buffers++;
1972                 list = &transaction->t_buffers;
1973                 break;
1974         case BJ_Forget:
1975                 list = &transaction->t_forget;
1976                 break;
1977         case BJ_IO:
1978                 list = &transaction->t_iobuf_list;
1979                 break;
1980         case BJ_Shadow:
1981                 list = &transaction->t_shadow_list;
1982                 break;
1983         case BJ_LogCtl:
1984                 list = &transaction->t_log_list;
1985                 break;
1986         case BJ_Reserved:
1987                 list = &transaction->t_reserved_list;
1988                 break;
1989         case BJ_Locked:
1990                 list =  &transaction->t_locked_list;
1991                 break;
1992         }
1993
1994         __blist_add_buffer(list, jh);
1995         jh->b_jlist = jlist;
1996
1997         if (was_dirty)
1998                 set_buffer_jbddirty(bh);
1999 }
2000
2001 void journal_file_buffer(struct journal_head *jh,
2002                                 transaction_t *transaction, int jlist)
2003 {
2004         jbd_lock_bh_state(jh2bh(jh));
2005         spin_lock(&transaction->t_journal->j_list_lock);
2006         __journal_file_buffer(jh, transaction, jlist);
2007         spin_unlock(&transaction->t_journal->j_list_lock);
2008         jbd_unlock_bh_state(jh2bh(jh));
2009 }
2010
2011 /*
2012  * Remove a buffer from its current buffer list in preparation for
2013  * dropping it from its current transaction entirely.  If the buffer has
2014  * already started to be used by a subsequent transaction, refile the
2015  * buffer on that transaction's metadata list.
2016  *
2017  * Called under journal->j_list_lock
2018  *
2019  * Called under jbd_lock_bh_state(jh2bh(jh))
2020  */
2021 void __journal_refile_buffer(struct journal_head *jh)
2022 {
2023         int was_dirty;
2024         struct buffer_head *bh = jh2bh(jh);
2025
2026         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
2027         if (jh->b_transaction)
2028                 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
2029
2030         /* If the buffer is now unused, just drop it. */
2031         if (jh->b_next_transaction == NULL) {
2032                 __journal_unfile_buffer(jh);
2033                 return;
2034         }
2035
2036         /*
2037          * It has been modified by a later transaction: add it to the new
2038          * transaction's metadata list.
2039          */
2040
2041         was_dirty = test_clear_buffer_jbddirty(bh);
2042         __journal_unfile_buffer(jh);
2043         jh->b_transaction = jh->b_next_transaction;
2044         jh->b_next_transaction = NULL;
2045         __journal_file_buffer(jh, jh->b_transaction, BJ_Metadata);
2046         J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
2047
2048         if (was_dirty)
2049                 set_buffer_jbddirty(bh);
2050 }
2051
2052 /*
2053  * For the unlocked version of this call, also make sure that any
2054  * hanging journal_head is cleaned up if necessary.
2055  *
2056  * __journal_refile_buffer is usually called as part of a single locked
2057  * operation on a buffer_head, in which the caller is probably going to
2058  * be hooking the journal_head onto other lists.  In that case it is up
2059  * to the caller to remove the journal_head if necessary.  For the
2060  * unlocked journal_refile_buffer call, the caller isn't going to be
2061  * doing anything else to the buffer so we need to do the cleanup
2062  * ourselves to avoid a jh leak.
2063  *
2064  * *** The journal_head may be freed by this call! ***
2065  */
2066 void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
2067 {
2068         struct buffer_head *bh = jh2bh(jh);
2069
2070         jbd_lock_bh_state(bh);
2071         spin_lock(&journal->j_list_lock);
2072
2073         __journal_refile_buffer(jh);
2074         jbd_unlock_bh_state(bh);
2075         journal_remove_journal_head(bh);
2076
2077         spin_unlock(&journal->j_list_lock);
2078         __brelse(bh);
2079 }