linux/fs/jbd/journal.c
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   1/*
   2 * linux/fs/jbd/journal.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 journal-writing code; part of the ext2fs
  13 * journaling system.
  14 *
  15 * This file manages journals: areas of disk reserved for logging
  16 * transactional updates.  This includes the kernel journaling thread
  17 * which is responsible for scheduling updates to the log.
  18 *
  19 * We do not actually manage the physical storage of the journal in this
  20 * file: that is left to a per-journal policy function, which allows us
  21 * to store the journal within a filesystem-specified area for ext2
  22 * journaling (ext2 can use a reserved inode for storing the log).
  23 */
  24
  25#include <linux/module.h>
  26#include <linux/time.h>
  27#include <linux/fs.h>
  28#include <linux/jbd.h>
  29#include <linux/errno.h>
  30#include <linux/slab.h>
  31#include <linux/init.h>
  32#include <linux/mm.h>
  33#include <linux/freezer.h>
  34#include <linux/pagemap.h>
  35#include <linux/kthread.h>
  36#include <linux/poison.h>
  37#include <linux/proc_fs.h>
  38#include <linux/debugfs.h>
  39
  40#include <asm/uaccess.h>
  41#include <asm/page.h>
  42
  43EXPORT_SYMBOL(journal_start);
  44EXPORT_SYMBOL(journal_restart);
  45EXPORT_SYMBOL(journal_extend);
  46EXPORT_SYMBOL(journal_stop);
  47EXPORT_SYMBOL(journal_lock_updates);
  48EXPORT_SYMBOL(journal_unlock_updates);
  49EXPORT_SYMBOL(journal_get_write_access);
  50EXPORT_SYMBOL(journal_get_create_access);
  51EXPORT_SYMBOL(journal_get_undo_access);
  52EXPORT_SYMBOL(journal_dirty_data);
  53EXPORT_SYMBOL(journal_dirty_metadata);
  54EXPORT_SYMBOL(journal_release_buffer);
  55EXPORT_SYMBOL(journal_forget);
  56#if 0
  57EXPORT_SYMBOL(journal_sync_buffer);
  58#endif
  59EXPORT_SYMBOL(journal_flush);
  60EXPORT_SYMBOL(journal_revoke);
  61
  62EXPORT_SYMBOL(journal_init_dev);
  63EXPORT_SYMBOL(journal_init_inode);
  64EXPORT_SYMBOL(journal_update_format);
  65EXPORT_SYMBOL(journal_check_used_features);
  66EXPORT_SYMBOL(journal_check_available_features);
  67EXPORT_SYMBOL(journal_set_features);
  68EXPORT_SYMBOL(journal_create);
  69EXPORT_SYMBOL(journal_load);
  70EXPORT_SYMBOL(journal_destroy);
  71EXPORT_SYMBOL(journal_update_superblock);
  72EXPORT_SYMBOL(journal_abort);
  73EXPORT_SYMBOL(journal_errno);
  74EXPORT_SYMBOL(journal_ack_err);
  75EXPORT_SYMBOL(journal_clear_err);
  76EXPORT_SYMBOL(log_wait_commit);
  77EXPORT_SYMBOL(journal_start_commit);
  78EXPORT_SYMBOL(journal_force_commit_nested);
  79EXPORT_SYMBOL(journal_wipe);
  80EXPORT_SYMBOL(journal_blocks_per_page);
  81EXPORT_SYMBOL(journal_invalidatepage);
  82EXPORT_SYMBOL(journal_try_to_free_buffers);
  83EXPORT_SYMBOL(journal_force_commit);
  84
  85static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
  86static void __journal_abort_soft (journal_t *journal, int errno);
  87
  88/*
  89 * Helper function used to manage commit timeouts
  90 */
  91
  92static void commit_timeout(unsigned long __data)
  93{
  94        struct task_struct * p = (struct task_struct *) __data;
  95
  96        wake_up_process(p);
  97}
  98
  99/*
 100 * kjournald: The main thread function used to manage a logging device
 101 * journal.
 102 *
 103 * This kernel thread is responsible for two things:
 104 *
 105 * 1) COMMIT:  Every so often we need to commit the current state of the
 106 *    filesystem to disk.  The journal thread is responsible for writing
 107 *    all of the metadata buffers to disk.
 108 *
 109 * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
 110 *    of the data in that part of the log has been rewritten elsewhere on
 111 *    the disk.  Flushing these old buffers to reclaim space in the log is
 112 *    known as checkpointing, and this thread is responsible for that job.
 113 */
 114
 115static int kjournald(void *arg)
 116{
 117        journal_t *journal = arg;
 118        transaction_t *transaction;
 119
 120        /*
 121         * Set up an interval timer which can be used to trigger a commit wakeup
 122         * after the commit interval expires
 123         */
 124        setup_timer(&journal->j_commit_timer, commit_timeout,
 125                        (unsigned long)current);
 126
 127        /* Record that the journal thread is running */
 128        journal->j_task = current;
 129        wake_up(&journal->j_wait_done_commit);
 130
 131        printk(KERN_INFO "kjournald starting.  Commit interval %ld seconds\n",
 132                        journal->j_commit_interval / HZ);
 133
 134        /*
 135         * And now, wait forever for commit wakeup events.
 136         */
 137        spin_lock(&journal->j_state_lock);
 138
 139loop:
 140        if (journal->j_flags & JFS_UNMOUNT)
 141                goto end_loop;
 142
 143        jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
 144                journal->j_commit_sequence, journal->j_commit_request);
 145
 146        if (journal->j_commit_sequence != journal->j_commit_request) {
 147                jbd_debug(1, "OK, requests differ\n");
 148                spin_unlock(&journal->j_state_lock);
 149                del_timer_sync(&journal->j_commit_timer);
 150                journal_commit_transaction(journal);
 151                spin_lock(&journal->j_state_lock);
 152                goto loop;
 153        }
 154
 155        wake_up(&journal->j_wait_done_commit);
 156        if (freezing(current)) {
 157                /*
 158                 * The simpler the better. Flushing journal isn't a
 159                 * good idea, because that depends on threads that may
 160                 * be already stopped.
 161                 */
 162                jbd_debug(1, "Now suspending kjournald\n");
 163                spin_unlock(&journal->j_state_lock);
 164                refrigerator();
 165                spin_lock(&journal->j_state_lock);
 166        } else {
 167                /*
 168                 * We assume on resume that commits are already there,
 169                 * so we don't sleep
 170                 */
 171                DEFINE_WAIT(wait);
 172                int should_sleep = 1;
 173
 174                prepare_to_wait(&journal->j_wait_commit, &wait,
 175                                TASK_INTERRUPTIBLE);
 176                if (journal->j_commit_sequence != journal->j_commit_request)
 177                        should_sleep = 0;
 178                transaction = journal->j_running_transaction;
 179                if (transaction && time_after_eq(jiffies,
 180                                                transaction->t_expires))
 181                        should_sleep = 0;
 182                if (journal->j_flags & JFS_UNMOUNT)
 183                        should_sleep = 0;
 184                if (should_sleep) {
 185                        spin_unlock(&journal->j_state_lock);
 186                        schedule();
 187                        spin_lock(&journal->j_state_lock);
 188                }
 189                finish_wait(&journal->j_wait_commit, &wait);
 190        }
 191
 192        jbd_debug(1, "kjournald wakes\n");
 193
 194        /*
 195         * Were we woken up by a commit wakeup event?
 196         */
 197        transaction = journal->j_running_transaction;
 198        if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
 199                journal->j_commit_request = transaction->t_tid;
 200                jbd_debug(1, "woke because of timeout\n");
 201        }
 202        goto loop;
 203
 204end_loop:
 205        spin_unlock(&journal->j_state_lock);
 206        del_timer_sync(&journal->j_commit_timer);
 207        journal->j_task = NULL;
 208        wake_up(&journal->j_wait_done_commit);
 209        jbd_debug(1, "Journal thread exiting.\n");
 210        return 0;
 211}
 212
 213static int journal_start_thread(journal_t *journal)
 214{
 215        struct task_struct *t;
 216
 217        t = kthread_run(kjournald, journal, "kjournald");
 218        if (IS_ERR(t))
 219                return PTR_ERR(t);
 220
 221        wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
 222        return 0;
 223}
 224
 225static void journal_kill_thread(journal_t *journal)
 226{
 227        spin_lock(&journal->j_state_lock);
 228        journal->j_flags |= JFS_UNMOUNT;
 229
 230        while (journal->j_task) {
 231                wake_up(&journal->j_wait_commit);
 232                spin_unlock(&journal->j_state_lock);
 233                wait_event(journal->j_wait_done_commit,
 234                                journal->j_task == NULL);
 235                spin_lock(&journal->j_state_lock);
 236        }
 237        spin_unlock(&journal->j_state_lock);
 238}
 239
 240/*
 241 * journal_write_metadata_buffer: write a metadata buffer to the journal.
 242 *
 243 * Writes a metadata buffer to a given disk block.  The actual IO is not
 244 * performed but a new buffer_head is constructed which labels the data
 245 * to be written with the correct destination disk block.
 246 *
 247 * Any magic-number escaping which needs to be done will cause a
 248 * copy-out here.  If the buffer happens to start with the
 249 * JFS_MAGIC_NUMBER, then we can't write it to the log directly: the
 250 * magic number is only written to the log for descripter blocks.  In
 251 * this case, we copy the data and replace the first word with 0, and we
 252 * return a result code which indicates that this buffer needs to be
 253 * marked as an escaped buffer in the corresponding log descriptor
 254 * block.  The missing word can then be restored when the block is read
 255 * during recovery.
 256 *
 257 * If the source buffer has already been modified by a new transaction
 258 * since we took the last commit snapshot, we use the frozen copy of
 259 * that data for IO.  If we end up using the existing buffer_head's data
 260 * for the write, then we *have* to lock the buffer to prevent anyone
 261 * else from using and possibly modifying it while the IO is in
 262 * progress.
 263 *
 264 * The function returns a pointer to the buffer_heads to be used for IO.
 265 *
 266 * We assume that the journal has already been locked in this function.
 267 *
 268 * Return value:
 269 *  <0: Error
 270 * >=0: Finished OK
 271 *
 272 * On success:
 273 * Bit 0 set == escape performed on the data
 274 * Bit 1 set == buffer copy-out performed (kfree the data after IO)
 275 */
 276
 277int journal_write_metadata_buffer(transaction_t *transaction,
 278                                  struct journal_head  *jh_in,
 279                                  struct journal_head **jh_out,
 280                                  unsigned long blocknr)
 281{
 282        int need_copy_out = 0;
 283        int done_copy_out = 0;
 284        int do_escape = 0;
 285        char *mapped_data;
 286        struct buffer_head *new_bh;
 287        struct journal_head *new_jh;
 288        struct page *new_page;
 289        unsigned int new_offset;
 290        struct buffer_head *bh_in = jh2bh(jh_in);
 291
 292        /*
 293         * The buffer really shouldn't be locked: only the current committing
 294         * transaction is allowed to write it, so nobody else is allowed
 295         * to do any IO.
 296         *
 297         * akpm: except if we're journalling data, and write() output is
 298         * also part of a shared mapping, and another thread has
 299         * decided to launch a writepage() against this buffer.
 300         */
 301        J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
 302
 303        new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
 304
 305        /*
 306         * If a new transaction has already done a buffer copy-out, then
 307         * we use that version of the data for the commit.
 308         */
 309        jbd_lock_bh_state(bh_in);
 310repeat:
 311        if (jh_in->b_frozen_data) {
 312                done_copy_out = 1;
 313                new_page = virt_to_page(jh_in->b_frozen_data);
 314                new_offset = offset_in_page(jh_in->b_frozen_data);
 315        } else {
 316                new_page = jh2bh(jh_in)->b_page;
 317                new_offset = offset_in_page(jh2bh(jh_in)->b_data);
 318        }
 319
 320        mapped_data = kmap_atomic(new_page, KM_USER0);
 321        /*
 322         * Check for escaping
 323         */
 324        if (*((__be32 *)(mapped_data + new_offset)) ==
 325                                cpu_to_be32(JFS_MAGIC_NUMBER)) {
 326                need_copy_out = 1;
 327                do_escape = 1;
 328        }
 329        kunmap_atomic(mapped_data, KM_USER0);
 330
 331        /*
 332         * Do we need to do a data copy?
 333         */
 334        if (need_copy_out && !done_copy_out) {
 335                char *tmp;
 336
 337                jbd_unlock_bh_state(bh_in);
 338                tmp = jbd_alloc(bh_in->b_size, GFP_NOFS);
 339                jbd_lock_bh_state(bh_in);
 340                if (jh_in->b_frozen_data) {
 341                        jbd_free(tmp, bh_in->b_size);
 342                        goto repeat;
 343                }
 344
 345                jh_in->b_frozen_data = tmp;
 346                mapped_data = kmap_atomic(new_page, KM_USER0);
 347                memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
 348                kunmap_atomic(mapped_data, KM_USER0);
 349
 350                new_page = virt_to_page(tmp);
 351                new_offset = offset_in_page(tmp);
 352                done_copy_out = 1;
 353        }
 354
 355        /*
 356         * Did we need to do an escaping?  Now we've done all the
 357         * copying, we can finally do so.
 358         */
 359        if (do_escape) {
 360                mapped_data = kmap_atomic(new_page, KM_USER0);
 361                *((unsigned int *)(mapped_data + new_offset)) = 0;
 362                kunmap_atomic(mapped_data, KM_USER0);
 363        }
 364
 365        /* keep subsequent assertions sane */
 366        new_bh->b_state = 0;
 367        init_buffer(new_bh, NULL, NULL);
 368        atomic_set(&new_bh->b_count, 1);
 369        jbd_unlock_bh_state(bh_in);
 370
 371        new_jh = journal_add_journal_head(new_bh);      /* This sleeps */
 372
 373        set_bh_page(new_bh, new_page, new_offset);
 374        new_jh->b_transaction = NULL;
 375        new_bh->b_size = jh2bh(jh_in)->b_size;
 376        new_bh->b_bdev = transaction->t_journal->j_dev;
 377        new_bh->b_blocknr = blocknr;
 378        set_buffer_mapped(new_bh);
 379        set_buffer_dirty(new_bh);
 380
 381        *jh_out = new_jh;
 382
 383        /*
 384         * The to-be-written buffer needs to get moved to the io queue,
 385         * and the original buffer whose contents we are shadowing or
 386         * copying is moved to the transaction's shadow queue.
 387         */
 388        JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
 389        journal_file_buffer(jh_in, transaction, BJ_Shadow);
 390        JBUFFER_TRACE(new_jh, "file as BJ_IO");
 391        journal_file_buffer(new_jh, transaction, BJ_IO);
 392
 393        return do_escape | (done_copy_out << 1);
 394}
 395
 396/*
 397 * Allocation code for the journal file.  Manage the space left in the
 398 * journal, so that we can begin checkpointing when appropriate.
 399 */
 400
 401/*
 402 * __log_space_left: Return the number of free blocks left in the journal.
 403 *
 404 * Called with the journal already locked.
 405 *
 406 * Called under j_state_lock
 407 */
 408
 409int __log_space_left(journal_t *journal)
 410{
 411        int left = journal->j_free;
 412
 413        assert_spin_locked(&journal->j_state_lock);
 414
 415        /*
 416         * Be pessimistic here about the number of those free blocks which
 417         * might be required for log descriptor control blocks.
 418         */
 419
 420#define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
 421
 422        left -= MIN_LOG_RESERVED_BLOCKS;
 423
 424        if (left <= 0)
 425                return 0;
 426        left -= (left >> 3);
 427        return left;
 428}
 429
 430/*
 431 * Called under j_state_lock.  Returns true if a transaction was started.
 432 */
 433int __log_start_commit(journal_t *journal, tid_t target)
 434{
 435        /*
 436         * Are we already doing a recent enough commit?
 437         */
 438        if (!tid_geq(journal->j_commit_request, target)) {
 439                /*
 440                 * We want a new commit: OK, mark the request and wakup the
 441                 * commit thread.  We do _not_ do the commit ourselves.
 442                 */
 443
 444                journal->j_commit_request = target;
 445                jbd_debug(1, "JBD: requesting commit %d/%d\n",
 446                          journal->j_commit_request,
 447                          journal->j_commit_sequence);
 448                wake_up(&journal->j_wait_commit);
 449                return 1;
 450        }
 451        return 0;
 452}
 453
 454int log_start_commit(journal_t *journal, tid_t tid)
 455{
 456        int ret;
 457
 458        spin_lock(&journal->j_state_lock);
 459        ret = __log_start_commit(journal, tid);
 460        spin_unlock(&journal->j_state_lock);
 461        return ret;
 462}
 463
 464/*
 465 * Force and wait upon a commit if the calling process is not within
 466 * transaction.  This is used for forcing out undo-protected data which contains
 467 * bitmaps, when the fs is running out of space.
 468 *
 469 * We can only force the running transaction if we don't have an active handle;
 470 * otherwise, we will deadlock.
 471 *
 472 * Returns true if a transaction was started.
 473 */
 474int journal_force_commit_nested(journal_t *journal)
 475{
 476        transaction_t *transaction = NULL;
 477        tid_t tid;
 478
 479        spin_lock(&journal->j_state_lock);
 480        if (journal->j_running_transaction && !current->journal_info) {
 481                transaction = journal->j_running_transaction;
 482                __log_start_commit(journal, transaction->t_tid);
 483        } else if (journal->j_committing_transaction)
 484                transaction = journal->j_committing_transaction;
 485
 486        if (!transaction) {
 487                spin_unlock(&journal->j_state_lock);
 488                return 0;       /* Nothing to retry */
 489        }
 490
 491        tid = transaction->t_tid;
 492        spin_unlock(&journal->j_state_lock);
 493        log_wait_commit(journal, tid);
 494        return 1;
 495}
 496
 497/*
 498 * Start a commit of the current running transaction (if any).  Returns true
 499 * if a transaction was started, and fills its tid in at *ptid
 500 */
 501int journal_start_commit(journal_t *journal, tid_t *ptid)
 502{
 503        int ret = 0;
 504
 505        spin_lock(&journal->j_state_lock);
 506        if (journal->j_running_transaction) {
 507                tid_t tid = journal->j_running_transaction->t_tid;
 508
 509                ret = __log_start_commit(journal, tid);
 510                if (ret && ptid)
 511                        *ptid = tid;
 512        } else if (journal->j_committing_transaction && ptid) {
 513                /*
 514                 * If ext3_write_super() recently started a commit, then we
 515                 * have to wait for completion of that transaction
 516                 */
 517                *ptid = journal->j_committing_transaction->t_tid;
 518                ret = 1;
 519        }
 520        spin_unlock(&journal->j_state_lock);
 521        return ret;
 522}
 523
 524/*
 525 * Wait for a specified commit to complete.
 526 * The caller may not hold the journal lock.
 527 */
 528int log_wait_commit(journal_t *journal, tid_t tid)
 529{
 530        int err = 0;
 531
 532#ifdef CONFIG_JBD_DEBUG
 533        spin_lock(&journal->j_state_lock);
 534        if (!tid_geq(journal->j_commit_request, tid)) {
 535                printk(KERN_EMERG
 536                       "%s: error: j_commit_request=%d, tid=%d\n",
 537                       __FUNCTION__, journal->j_commit_request, tid);
 538        }
 539        spin_unlock(&journal->j_state_lock);
 540#endif
 541        spin_lock(&journal->j_state_lock);
 542        while (tid_gt(tid, journal->j_commit_sequence)) {
 543                jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
 544                                  tid, journal->j_commit_sequence);
 545                wake_up(&journal->j_wait_commit);
 546                spin_unlock(&journal->j_state_lock);
 547                wait_event(journal->j_wait_done_commit,
 548                                !tid_gt(tid, journal->j_commit_sequence));
 549                spin_lock(&journal->j_state_lock);
 550        }
 551        spin_unlock(&journal->j_state_lock);
 552
 553        if (unlikely(is_journal_aborted(journal))) {
 554                printk(KERN_EMERG "journal commit I/O error\n");
 555                err = -EIO;
 556        }
 557        return err;
 558}
 559
 560/*
 561 * Log buffer allocation routines:
 562 */
 563
 564int journal_next_log_block(journal_t *journal, unsigned long *retp)
 565{
 566        unsigned long blocknr;
 567
 568        spin_lock(&journal->j_state_lock);
 569        J_ASSERT(journal->j_free > 1);
 570
 571        blocknr = journal->j_head;
 572        journal->j_head++;
 573        journal->j_free--;
 574        if (journal->j_head == journal->j_last)
 575                journal->j_head = journal->j_first;
 576        spin_unlock(&journal->j_state_lock);
 577        return journal_bmap(journal, blocknr, retp);
 578}
 579
 580/*
 581 * Conversion of logical to physical block numbers for the journal
 582 *
 583 * On external journals the journal blocks are identity-mapped, so
 584 * this is a no-op.  If needed, we can use j_blk_offset - everything is
 585 * ready.
 586 */
 587int journal_bmap(journal_t *journal, unsigned long blocknr,
 588                 unsigned long *retp)
 589{
 590        int err = 0;
 591        unsigned long ret;
 592
 593        if (journal->j_inode) {
 594                ret = bmap(journal->j_inode, blocknr);
 595                if (ret)
 596                        *retp = ret;
 597                else {
 598                        char b[BDEVNAME_SIZE];
 599
 600                        printk(KERN_ALERT "%s: journal block not found "
 601                                        "at offset %lu on %s\n",
 602                                __FUNCTION__,
 603                                blocknr,
 604                                bdevname(journal->j_dev, b));
 605                        err = -EIO;
 606                        __journal_abort_soft(journal, err);
 607                }
 608        } else {
 609                *retp = blocknr; /* +journal->j_blk_offset */
 610        }
 611        return err;
 612}
 613
 614/*
 615 * We play buffer_head aliasing tricks to write data/metadata blocks to
 616 * the journal without copying their contents, but for journal
 617 * descriptor blocks we do need to generate bona fide buffers.
 618 *
 619 * After the caller of journal_get_descriptor_buffer() has finished modifying
 620 * the buffer's contents they really should run flush_dcache_page(bh->b_page).
 621 * But we don't bother doing that, so there will be coherency problems with
 622 * mmaps of blockdevs which hold live JBD-controlled filesystems.
 623 */
 624struct journal_head *journal_get_descriptor_buffer(journal_t *journal)
 625{
 626        struct buffer_head *bh;
 627        unsigned long blocknr;
 628        int err;
 629
 630        err = journal_next_log_block(journal, &blocknr);
 631
 632        if (err)
 633                return NULL;
 634
 635        bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 636        lock_buffer(bh);
 637        memset(bh->b_data, 0, journal->j_blocksize);
 638        set_buffer_uptodate(bh);
 639        unlock_buffer(bh);
 640        BUFFER_TRACE(bh, "return this buffer");
 641        return journal_add_journal_head(bh);
 642}
 643
 644/*
 645 * Management for journal control blocks: functions to create and
 646 * destroy journal_t structures, and to initialise and read existing
 647 * journal blocks from disk.  */
 648
 649/* First: create and setup a journal_t object in memory.  We initialise
 650 * very few fields yet: that has to wait until we have created the
 651 * journal structures from from scratch, or loaded them from disk. */
 652
 653static journal_t * journal_init_common (void)
 654{
 655        journal_t *journal;
 656        int err;
 657
 658        journal = kzalloc(sizeof(*journal), GFP_KERNEL);
 659        if (!journal)
 660                goto fail;
 661
 662        init_waitqueue_head(&journal->j_wait_transaction_locked);
 663        init_waitqueue_head(&journal->j_wait_logspace);
 664        init_waitqueue_head(&journal->j_wait_done_commit);
 665        init_waitqueue_head(&journal->j_wait_checkpoint);
 666        init_waitqueue_head(&journal->j_wait_commit);
 667        init_waitqueue_head(&journal->j_wait_updates);
 668        mutex_init(&journal->j_barrier);
 669        mutex_init(&journal->j_checkpoint_mutex);
 670        spin_lock_init(&journal->j_revoke_lock);
 671        spin_lock_init(&journal->j_list_lock);
 672        spin_lock_init(&journal->j_state_lock);
 673
 674        journal->j_commit_interval = (HZ * JBD_DEFAULT_MAX_COMMIT_AGE);
 675
 676        /* The journal is marked for error until we succeed with recovery! */
 677        journal->j_flags = JFS_ABORT;
 678
 679        /* Set up a default-sized revoke table for the new mount. */
 680        err = journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
 681        if (err) {
 682                kfree(journal);
 683                goto fail;
 684        }
 685        return journal;
 686fail:
 687        return NULL;
 688}
 689
 690/* journal_init_dev and journal_init_inode:
 691 *
 692 * Create a journal structure assigned some fixed set of disk blocks to
 693 * the journal.  We don't actually touch those disk blocks yet, but we
 694 * need to set up all of the mapping information to tell the journaling
 695 * system where the journal blocks are.
 696 *
 697 */
 698
 699/**
 700 *  journal_t * journal_init_dev() - creates an initialises a journal structure
 701 *  @bdev: Block device on which to create the journal
 702 *  @fs_dev: Device which hold journalled filesystem for this journal.
 703 *  @start: Block nr Start of journal.
 704 *  @len:  Length of the journal in blocks.
 705 *  @blocksize: blocksize of journalling device
 706 *  @returns: a newly created journal_t *
 707 *
 708 *  journal_init_dev creates a journal which maps a fixed contiguous
 709 *  range of blocks on an arbitrary block device.
 710 *
 711 */
 712journal_t * journal_init_dev(struct block_device *bdev,
 713                        struct block_device *fs_dev,
 714                        int start, int len, int blocksize)
 715{
 716        journal_t *journal = journal_init_common();
 717        struct buffer_head *bh;
 718        int n;
 719
 720        if (!journal)
 721                return NULL;
 722
 723        /* journal descriptor can store up to n blocks -bzzz */
 724        journal->j_blocksize = blocksize;
 725        n = journal->j_blocksize / sizeof(journal_block_tag_t);
 726        journal->j_wbufsize = n;
 727        journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
 728        if (!journal->j_wbuf) {
 729                printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
 730                        __FUNCTION__);
 731                kfree(journal);
 732                journal = NULL;
 733                goto out;
 734        }
 735        journal->j_dev = bdev;
 736        journal->j_fs_dev = fs_dev;
 737        journal->j_blk_offset = start;
 738        journal->j_maxlen = len;
 739
 740        bh = __getblk(journal->j_dev, start, journal->j_blocksize);
 741        J_ASSERT(bh != NULL);
 742        journal->j_sb_buffer = bh;
 743        journal->j_superblock = (journal_superblock_t *)bh->b_data;
 744out:
 745        return journal;
 746}
 747
 748/**
 749 *  journal_t * journal_init_inode () - creates a journal which maps to a inode.
 750 *  @inode: An inode to create the journal in
 751 *
 752 * journal_init_inode creates a journal which maps an on-disk inode as
 753 * the journal.  The inode must exist already, must support bmap() and
 754 * must have all data blocks preallocated.
 755 */
 756journal_t * journal_init_inode (struct inode *inode)
 757{
 758        struct buffer_head *bh;
 759        journal_t *journal = journal_init_common();
 760        int err;
 761        int n;
 762        unsigned long blocknr;
 763
 764        if (!journal)
 765                return NULL;
 766
 767        journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
 768        journal->j_inode = inode;
 769        jbd_debug(1,
 770                  "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
 771                  journal, inode->i_sb->s_id, inode->i_ino,
 772                  (long long) inode->i_size,
 773                  inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
 774
 775        journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
 776        journal->j_blocksize = inode->i_sb->s_blocksize;
 777
 778        /* journal descriptor can store up to n blocks -bzzz */
 779        n = journal->j_blocksize / sizeof(journal_block_tag_t);
 780        journal->j_wbufsize = n;
 781        journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
 782        if (!journal->j_wbuf) {
 783                printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
 784                        __FUNCTION__);
 785                kfree(journal);
 786                return NULL;
 787        }
 788
 789        err = journal_bmap(journal, 0, &blocknr);
 790        /* If that failed, give up */
 791        if (err) {
 792                printk(KERN_ERR "%s: Cannnot locate journal superblock\n",
 793                       __FUNCTION__);
 794                kfree(journal);
 795                return NULL;
 796        }
 797
 798        bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 799        J_ASSERT(bh != NULL);
 800        journal->j_sb_buffer = bh;
 801        journal->j_superblock = (journal_superblock_t *)bh->b_data;
 802
 803        return journal;
 804}
 805
 806/*
 807 * If the journal init or create aborts, we need to mark the journal
 808 * superblock as being NULL to prevent the journal destroy from writing
 809 * back a bogus superblock.
 810 */
 811static void journal_fail_superblock (journal_t *journal)
 812{
 813        struct buffer_head *bh = journal->j_sb_buffer;
 814        brelse(bh);
 815        journal->j_sb_buffer = NULL;
 816}
 817
 818/*
 819 * Given a journal_t structure, initialise the various fields for
 820 * startup of a new journaling session.  We use this both when creating
 821 * a journal, and after recovering an old journal to reset it for
 822 * subsequent use.
 823 */
 824
 825static int journal_reset(journal_t *journal)
 826{
 827        journal_superblock_t *sb = journal->j_superblock;
 828        unsigned long first, last;
 829
 830        first = be32_to_cpu(sb->s_first);
 831        last = be32_to_cpu(sb->s_maxlen);
 832
 833        journal->j_first = first;
 834        journal->j_last = last;
 835
 836        journal->j_head = first;
 837        journal->j_tail = first;
 838        journal->j_free = last - first;
 839
 840        journal->j_tail_sequence = journal->j_transaction_sequence;
 841        journal->j_commit_sequence = journal->j_transaction_sequence - 1;
 842        journal->j_commit_request = journal->j_commit_sequence;
 843
 844        journal->j_max_transaction_buffers = journal->j_maxlen / 4;
 845
 846        /* Add the dynamic fields and write it to disk. */
 847        journal_update_superblock(journal, 1);
 848        return journal_start_thread(journal);
 849}
 850
 851/**
 852 * int journal_create() - Initialise the new journal file
 853 * @journal: Journal to create. This structure must have been initialised
 854 *
 855 * Given a journal_t structure which tells us which disk blocks we can
 856 * use, create a new journal superblock and initialise all of the
 857 * journal fields from scratch.
 858 **/
 859int journal_create(journal_t *journal)
 860{
 861        unsigned long blocknr;
 862        struct buffer_head *bh;
 863        journal_superblock_t *sb;
 864        int i, err;
 865
 866        if (journal->j_maxlen < JFS_MIN_JOURNAL_BLOCKS) {
 867                printk (KERN_ERR "Journal length (%d blocks) too short.\n",
 868                        journal->j_maxlen);
 869                journal_fail_superblock(journal);
 870                return -EINVAL;
 871        }
 872
 873        if (journal->j_inode == NULL) {
 874                /*
 875                 * We don't know what block to start at!
 876                 */
 877                printk(KERN_EMERG
 878                       "%s: creation of journal on external device!\n",
 879                       __FUNCTION__);
 880                BUG();
 881        }
 882
 883        /* Zero out the entire journal on disk.  We cannot afford to
 884           have any blocks on disk beginning with JFS_MAGIC_NUMBER. */
 885        jbd_debug(1, "JBD: Zeroing out journal blocks...\n");
 886        for (i = 0; i < journal->j_maxlen; i++) {
 887                err = journal_bmap(journal, i, &blocknr);
 888                if (err)
 889                        return err;
 890                bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 891                lock_buffer(bh);
 892                memset (bh->b_data, 0, journal->j_blocksize);
 893                BUFFER_TRACE(bh, "marking dirty");
 894                mark_buffer_dirty(bh);
 895                BUFFER_TRACE(bh, "marking uptodate");
 896                set_buffer_uptodate(bh);
 897                unlock_buffer(bh);
 898                __brelse(bh);
 899        }
 900
 901        sync_blockdev(journal->j_dev);
 902        jbd_debug(1, "JBD: journal cleared.\n");
 903
 904        /* OK, fill in the initial static fields in the new superblock */
 905        sb = journal->j_superblock;
 906
 907        sb->s_header.h_magic     = cpu_to_be32(JFS_MAGIC_NUMBER);
 908        sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
 909
 910        sb->s_blocksize = cpu_to_be32(journal->j_blocksize);
 911        sb->s_maxlen    = cpu_to_be32(journal->j_maxlen);
 912        sb->s_first     = cpu_to_be32(1);
 913
 914        journal->j_transaction_sequence = 1;
 915
 916        journal->j_flags &= ~JFS_ABORT;
 917        journal->j_format_version = 2;
 918
 919        return journal_reset(journal);
 920}
 921
 922/**
 923 * void journal_update_superblock() - Update journal sb on disk.
 924 * @journal: The journal to update.
 925 * @wait: Set to '0' if you don't want to wait for IO completion.
 926 *
 927 * Update a journal's dynamic superblock fields and write it to disk,
 928 * optionally waiting for the IO to complete.
 929 */
 930void journal_update_superblock(journal_t *journal, int wait)
 931{
 932        journal_superblock_t *sb = journal->j_superblock;
 933        struct buffer_head *bh = journal->j_sb_buffer;
 934
 935        /*
 936         * As a special case, if the on-disk copy is already marked as needing
 937         * no recovery (s_start == 0) and there are no outstanding transactions
 938         * in the filesystem, then we can safely defer the superblock update
 939         * until the next commit by setting JFS_FLUSHED.  This avoids
 940         * attempting a write to a potential-readonly device.
 941         */
 942        if (sb->s_start == 0 && journal->j_tail_sequence ==
 943                                journal->j_transaction_sequence) {
 944                jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
 945                        "(start %ld, seq %d, errno %d)\n",
 946                        journal->j_tail, journal->j_tail_sequence,
 947                        journal->j_errno);
 948                goto out;
 949        }
 950
 951        spin_lock(&journal->j_state_lock);
 952        jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n",
 953                  journal->j_tail, journal->j_tail_sequence, journal->j_errno);
 954
 955        sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
 956        sb->s_start    = cpu_to_be32(journal->j_tail);
 957        sb->s_errno    = cpu_to_be32(journal->j_errno);
 958        spin_unlock(&journal->j_state_lock);
 959
 960        BUFFER_TRACE(bh, "marking dirty");
 961        mark_buffer_dirty(bh);
 962        if (wait)
 963                sync_dirty_buffer(bh);
 964        else
 965                ll_rw_block(SWRITE, 1, &bh);
 966
 967out:
 968        /* If we have just flushed the log (by marking s_start==0), then
 969         * any future commit will have to be careful to update the
 970         * superblock again to re-record the true start of the log. */
 971
 972        spin_lock(&journal->j_state_lock);
 973        if (sb->s_start)
 974                journal->j_flags &= ~JFS_FLUSHED;
 975        else
 976                journal->j_flags |= JFS_FLUSHED;
 977        spin_unlock(&journal->j_state_lock);
 978}
 979
 980/*
 981 * Read the superblock for a given journal, performing initial
 982 * validation of the format.
 983 */
 984
 985static int journal_get_superblock(journal_t *journal)
 986{
 987        struct buffer_head *bh;
 988        journal_superblock_t *sb;
 989        int err = -EIO;
 990
 991        bh = journal->j_sb_buffer;
 992
 993        J_ASSERT(bh != NULL);
 994        if (!buffer_uptodate(bh)) {
 995                ll_rw_block(READ, 1, &bh);
 996                wait_on_buffer(bh);
 997                if (!buffer_uptodate(bh)) {
 998                        printk (KERN_ERR
 999                                "JBD: IO error reading journal superblock\n");
1000                        goto out;
1001                }
1002        }
1003
1004        sb = journal->j_superblock;
1005
1006        err = -EINVAL;
1007
1008        if (sb->s_header.h_magic != cpu_to_be32(JFS_MAGIC_NUMBER) ||
1009            sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1010                printk(KERN_WARNING "JBD: no valid journal superblock found\n");
1011                goto out;
1012        }
1013
1014        switch(be32_to_cpu(sb->s_header.h_blocktype)) {
1015        case JFS_SUPERBLOCK_V1:
1016                journal->j_format_version = 1;
1017                break;
1018        case JFS_SUPERBLOCK_V2:
1019                journal->j_format_version = 2;
1020                break;
1021        default:
1022                printk(KERN_WARNING "JBD: unrecognised superblock format ID\n");
1023                goto out;
1024        }
1025
1026        if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
1027                journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
1028        else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
1029                printk (KERN_WARNING "JBD: journal file too short\n");
1030                goto out;
1031        }
1032
1033        return 0;
1034
1035out:
1036        journal_fail_superblock(journal);
1037        return err;
1038}
1039
1040/*
1041 * Load the on-disk journal superblock and read the key fields into the
1042 * journal_t.
1043 */
1044
1045static int load_superblock(journal_t *journal)
1046{
1047        int err;
1048        journal_superblock_t *sb;
1049
1050        err = journal_get_superblock(journal);
1051        if (err)
1052                return err;
1053
1054        sb = journal->j_superblock;
1055
1056        journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1057        journal->j_tail = be32_to_cpu(sb->s_start);
1058        journal->j_first = be32_to_cpu(sb->s_first);
1059        journal->j_last = be32_to_cpu(sb->s_maxlen);
1060        journal->j_errno = be32_to_cpu(sb->s_errno);
1061
1062        return 0;
1063}
1064
1065
1066/**
1067 * int journal_load() - Read journal from disk.
1068 * @journal: Journal to act on.
1069 *
1070 * Given a journal_t structure which tells us which disk blocks contain
1071 * a journal, read the journal from disk to initialise the in-memory
1072 * structures.
1073 */
1074int journal_load(journal_t *journal)
1075{
1076        int err;
1077        journal_superblock_t *sb;
1078
1079        err = load_superblock(journal);
1080        if (err)
1081                return err;
1082
1083        sb = journal->j_superblock;
1084        /* If this is a V2 superblock, then we have to check the
1085         * features flags on it. */
1086
1087        if (journal->j_format_version >= 2) {
1088                if ((sb->s_feature_ro_compat &
1089                     ~cpu_to_be32(JFS_KNOWN_ROCOMPAT_FEATURES)) ||
1090                    (sb->s_feature_incompat &
1091                     ~cpu_to_be32(JFS_KNOWN_INCOMPAT_FEATURES))) {
1092                        printk (KERN_WARNING
1093                                "JBD: Unrecognised features on journal\n");
1094                        return -EINVAL;
1095                }
1096        }
1097
1098        /* Let the recovery code check whether it needs to recover any
1099         * data from the journal. */
1100        if (journal_recover(journal))
1101                goto recovery_error;
1102
1103        /* OK, we've finished with the dynamic journal bits:
1104         * reinitialise the dynamic contents of the superblock in memory
1105         * and reset them on disk. */
1106        if (journal_reset(journal))
1107                goto recovery_error;
1108
1109        journal->j_flags &= ~JFS_ABORT;
1110        journal->j_flags |= JFS_LOADED;
1111        return 0;
1112
1113recovery_error:
1114        printk (KERN_WARNING "JBD: recovery failed\n");
1115        return -EIO;
1116}
1117
1118/**
1119 * void journal_destroy() - Release a journal_t structure.
1120 * @journal: Journal to act on.
1121 *
1122 * Release a journal_t structure once it is no longer in use by the
1123 * journaled object.
1124 */
1125void journal_destroy(journal_t *journal)
1126{
1127        /* Wait for the commit thread to wake up and die. */
1128        journal_kill_thread(journal);
1129
1130        /* Force a final log commit */
1131        if (journal->j_running_transaction)
1132                journal_commit_transaction(journal);
1133
1134        /* Force any old transactions to disk */
1135
1136        /* Totally anal locking here... */
1137        spin_lock(&journal->j_list_lock);
1138        while (journal->j_checkpoint_transactions != NULL) {
1139                spin_unlock(&journal->j_list_lock);
1140                log_do_checkpoint(journal);
1141                spin_lock(&journal->j_list_lock);
1142        }
1143
1144        J_ASSERT(journal->j_running_transaction == NULL);
1145        J_ASSERT(journal->j_committing_transaction == NULL);
1146        J_ASSERT(journal->j_checkpoint_transactions == NULL);
1147        spin_unlock(&journal->j_list_lock);
1148
1149        /* We can now mark the journal as empty. */
1150        journal->j_tail = 0;
1151        journal->j_tail_sequence = ++journal->j_transaction_sequence;
1152        if (journal->j_sb_buffer) {
1153                journal_update_superblock(journal, 1);
1154                brelse(journal->j_sb_buffer);
1155        }
1156
1157        if (journal->j_inode)
1158                iput(journal->j_inode);
1159        if (journal->j_revoke)
1160                journal_destroy_revoke(journal);
1161        kfree(journal->j_wbuf);
1162        kfree(journal);
1163}
1164
1165
1166/**
1167 *int journal_check_used_features () - Check if features specified are used.
1168 * @journal: Journal to check.
1169 * @compat: bitmask of compatible features
1170 * @ro: bitmask of features that force read-only mount
1171 * @incompat: bitmask of incompatible features
1172 *
1173 * Check whether the journal uses all of a given set of
1174 * features.  Return true (non-zero) if it does.
1175 **/
1176
1177int journal_check_used_features (journal_t *journal, unsigned long compat,
1178                                 unsigned long ro, unsigned long incompat)
1179{
1180        journal_superblock_t *sb;
1181
1182        if (!compat && !ro && !incompat)
1183                return 1;
1184        if (journal->j_format_version == 1)
1185                return 0;
1186
1187        sb = journal->j_superblock;
1188
1189        if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1190            ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1191            ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1192                return 1;
1193
1194        return 0;
1195}
1196
1197/**
1198 * int journal_check_available_features() - Check feature set in journalling layer
1199 * @journal: Journal to check.
1200 * @compat: bitmask of compatible features
1201 * @ro: bitmask of features that force read-only mount
1202 * @incompat: bitmask of incompatible features
1203 *
1204 * Check whether the journaling code supports the use of
1205 * all of a given set of features on this journal.  Return true
1206 * (non-zero) if it can. */
1207
1208int journal_check_available_features (journal_t *journal, unsigned long compat,
1209                                      unsigned long ro, unsigned long incompat)
1210{
1211        journal_superblock_t *sb;
1212
1213        if (!compat && !ro && !incompat)
1214                return 1;
1215
1216        sb = journal->j_superblock;
1217
1218        /* We can support any known requested features iff the
1219         * superblock is in version 2.  Otherwise we fail to support any
1220         * extended sb features. */
1221
1222        if (journal->j_format_version != 2)
1223                return 0;
1224
1225        if ((compat   & JFS_KNOWN_COMPAT_FEATURES) == compat &&
1226            (ro       & JFS_KNOWN_ROCOMPAT_FEATURES) == ro &&
1227            (incompat & JFS_KNOWN_INCOMPAT_FEATURES) == incompat)
1228                return 1;
1229
1230        return 0;
1231}
1232
1233/**
1234 * int journal_set_features () - Mark a given journal feature in the superblock
1235 * @journal: Journal to act on.
1236 * @compat: bitmask of compatible features
1237 * @ro: bitmask of features that force read-only mount
1238 * @incompat: bitmask of incompatible features
1239 *
1240 * Mark a given journal feature as present on the
1241 * superblock.  Returns true if the requested features could be set.
1242 *
1243 */
1244
1245int journal_set_features (journal_t *journal, unsigned long compat,
1246                          unsigned long ro, unsigned long incompat)
1247{
1248        journal_superblock_t *sb;
1249
1250        if (journal_check_used_features(journal, compat, ro, incompat))
1251                return 1;
1252
1253        if (!journal_check_available_features(journal, compat, ro, incompat))
1254                return 0;
1255
1256        jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1257                  compat, ro, incompat);
1258
1259        sb = journal->j_superblock;
1260
1261        sb->s_feature_compat    |= cpu_to_be32(compat);
1262        sb->s_feature_ro_compat |= cpu_to_be32(ro);
1263        sb->s_feature_incompat  |= cpu_to_be32(incompat);
1264
1265        return 1;
1266}
1267
1268
1269/**
1270 * int journal_update_format () - Update on-disk journal structure.
1271 * @journal: Journal to act on.
1272 *
1273 * Given an initialised but unloaded journal struct, poke about in the
1274 * on-disk structure to update it to the most recent supported version.
1275 */
1276int journal_update_format (journal_t *journal)
1277{
1278        journal_superblock_t *sb;
1279        int err;
1280
1281        err = journal_get_superblock(journal);
1282        if (err)
1283                return err;
1284
1285        sb = journal->j_superblock;
1286
1287        switch (be32_to_cpu(sb->s_header.h_blocktype)) {
1288        case JFS_SUPERBLOCK_V2:
1289                return 0;
1290        case JFS_SUPERBLOCK_V1:
1291                return journal_convert_superblock_v1(journal, sb);
1292        default:
1293                break;
1294        }
1295        return -EINVAL;
1296}
1297
1298static int journal_convert_superblock_v1(journal_t *journal,
1299                                         journal_superblock_t *sb)
1300{
1301        int offset, blocksize;
1302        struct buffer_head *bh;
1303
1304        printk(KERN_WARNING
1305                "JBD: Converting superblock from version 1 to 2.\n");
1306
1307        /* Pre-initialise new fields to zero */
1308        offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb);
1309        blocksize = be32_to_cpu(sb->s_blocksize);
1310        memset(&sb->s_feature_compat, 0, blocksize-offset);
1311
1312        sb->s_nr_users = cpu_to_be32(1);
1313        sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
1314        journal->j_format_version = 2;
1315
1316        bh = journal->j_sb_buffer;
1317        BUFFER_TRACE(bh, "marking dirty");
1318        mark_buffer_dirty(bh);
1319        sync_dirty_buffer(bh);
1320        return 0;
1321}
1322
1323
1324/**
1325 * int journal_flush () - Flush journal
1326 * @journal: Journal to act on.
1327 *
1328 * Flush all data for a given journal to disk and empty the journal.
1329 * Filesystems can use this when remounting readonly to ensure that
1330 * recovery does not need to happen on remount.
1331 */
1332
1333int journal_flush(journal_t *journal)
1334{
1335        int err = 0;
1336        transaction_t *transaction = NULL;
1337        unsigned long old_tail;
1338
1339        spin_lock(&journal->j_state_lock);
1340
1341        /* Force everything buffered to the log... */
1342        if (journal->j_running_transaction) {
1343                transaction = journal->j_running_transaction;
1344                __log_start_commit(journal, transaction->t_tid);
1345        } else if (journal->j_committing_transaction)
1346                transaction = journal->j_committing_transaction;
1347
1348        /* Wait for the log commit to complete... */
1349        if (transaction) {
1350                tid_t tid = transaction->t_tid;
1351
1352                spin_unlock(&journal->j_state_lock);
1353                log_wait_commit(journal, tid);
1354        } else {
1355                spin_unlock(&journal->j_state_lock);
1356        }
1357
1358        /* ...and flush everything in the log out to disk. */
1359        spin_lock(&journal->j_list_lock);
1360        while (!err && journal->j_checkpoint_transactions != NULL) {
1361                spin_unlock(&journal->j_list_lock);
1362                err = log_do_checkpoint(journal);
1363                spin_lock(&journal->j_list_lock);
1364        }
1365        spin_unlock(&journal->j_list_lock);
1366        cleanup_journal_tail(journal);
1367
1368        /* Finally, mark the journal as really needing no recovery.
1369         * This sets s_start==0 in the underlying superblock, which is
1370         * the magic code for a fully-recovered superblock.  Any future
1371         * commits of data to the journal will restore the current
1372         * s_start value. */
1373        spin_lock(&journal->j_state_lock);
1374        old_tail = journal->j_tail;
1375        journal->j_tail = 0;
1376        spin_unlock(&journal->j_state_lock);
1377        journal_update_superblock(journal, 1);
1378        spin_lock(&journal->j_state_lock);
1379        journal->j_tail = old_tail;
1380
1381        J_ASSERT(!journal->j_running_transaction);
1382        J_ASSERT(!journal->j_committing_transaction);
1383        J_ASSERT(!journal->j_checkpoint_transactions);
1384        J_ASSERT(journal->j_head == journal->j_tail);
1385        J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1386        spin_unlock(&journal->j_state_lock);
1387        return err;
1388}
1389
1390/**
1391 * int journal_wipe() - Wipe journal contents
1392 * @journal: Journal to act on.
1393 * @write: flag (see below)
1394 *
1395 * Wipe out all of the contents of a journal, safely.  This will produce
1396 * a warning if the journal contains any valid recovery information.
1397 * Must be called between journal_init_*() and journal_load().
1398 *
1399 * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
1400 * we merely suppress recovery.
1401 */
1402
1403int journal_wipe(journal_t *journal, int write)
1404{
1405        journal_superblock_t *sb;
1406        int err = 0;
1407
1408        J_ASSERT (!(journal->j_flags & JFS_LOADED));
1409
1410        err = load_superblock(journal);
1411        if (err)
1412                return err;
1413
1414        sb = journal->j_superblock;
1415
1416        if (!journal->j_tail)
1417                goto no_recovery;
1418
1419        printk (KERN_WARNING "JBD: %s recovery information on journal\n",
1420                write ? "Clearing" : "Ignoring");
1421
1422        err = journal_skip_recovery(journal);
1423        if (write)
1424                journal_update_superblock(journal, 1);
1425
1426 no_recovery:
1427        return err;
1428}
1429
1430/*
1431 * journal_dev_name: format a character string to describe on what
1432 * device this journal is present.
1433 */
1434
1435static const char *journal_dev_name(journal_t *journal, char *buffer)
1436{
1437        struct block_device *bdev;
1438
1439        if (journal->j_inode)
1440                bdev = journal->j_inode->i_sb->s_bdev;
1441        else
1442                bdev = journal->j_dev;
1443
1444        return bdevname(bdev, buffer);
1445}
1446
1447/*
1448 * Journal abort has very specific semantics, which we describe
1449 * for journal abort.
1450 *
1451 * Two internal function, which provide abort to te jbd layer
1452 * itself are here.
1453 */
1454
1455/*
1456 * Quick version for internal journal use (doesn't lock the journal).
1457 * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
1458 * and don't attempt to make any other journal updates.
1459 */
1460void __journal_abort_hard(journal_t *journal)
1461{
1462        transaction_t *transaction;
1463        char b[BDEVNAME_SIZE];
1464
1465        if (journal->j_flags & JFS_ABORT)
1466                return;
1467
1468        printk(KERN_ERR "Aborting journal on device %s.\n",
1469                journal_dev_name(journal, b));
1470
1471        spin_lock(&journal->j_state_lock);
1472        journal->j_flags |= JFS_ABORT;
1473        transaction = journal->j_running_transaction;
1474        if (transaction)
1475                __log_start_commit(journal, transaction->t_tid);
1476        spin_unlock(&journal->j_state_lock);
1477}
1478
1479/* Soft abort: record the abort error status in the journal superblock,
1480 * but don't do any other IO. */
1481static void __journal_abort_soft (journal_t *journal, int errno)
1482{
1483        if (journal->j_flags & JFS_ABORT)
1484                return;
1485
1486        if (!journal->j_errno)
1487                journal->j_errno = errno;
1488
1489        __journal_abort_hard(journal);
1490
1491        if (errno)
1492                journal_update_superblock(journal, 1);
1493}
1494
1495/**
1496 * void journal_abort () - Shutdown the journal immediately.
1497 * @journal: the journal to shutdown.
1498 * @errno:   an error number to record in the journal indicating
1499 *           the reason for the shutdown.
1500 *
1501 * Perform a complete, immediate shutdown of the ENTIRE
1502 * journal (not of a single transaction).  This operation cannot be
1503 * undone without closing and reopening the journal.
1504 *
1505 * The journal_abort function is intended to support higher level error
1506 * recovery mechanisms such as the ext2/ext3 remount-readonly error
1507 * mode.
1508 *
1509 * Journal abort has very specific semantics.  Any existing dirty,
1510 * unjournaled buffers in the main filesystem will still be written to
1511 * disk by bdflush, but the journaling mechanism will be suspended
1512 * immediately and no further transaction commits will be honoured.
1513 *
1514 * Any dirty, journaled buffers will be written back to disk without
1515 * hitting the journal.  Atomicity cannot be guaranteed on an aborted
1516 * filesystem, but we _do_ attempt to leave as much data as possible
1517 * behind for fsck to use for cleanup.
1518 *
1519 * Any attempt to get a new transaction handle on a journal which is in
1520 * ABORT state will just result in an -EROFS error return.  A
1521 * journal_stop on an existing handle will return -EIO if we have
1522 * entered abort state during the update.
1523 *
1524 * Recursive transactions are not disturbed by journal abort until the
1525 * final journal_stop, which will receive the -EIO error.
1526 *
1527 * Finally, the journal_abort call allows the caller to supply an errno
1528 * which will be recorded (if possible) in the journal superblock.  This
1529 * allows a client to record failure conditions in the middle of a
1530 * transaction without having to complete the transaction to record the
1531 * failure to disk.  ext3_error, for example, now uses this
1532 * functionality.
1533 *
1534 * Errors which originate from within the journaling layer will NOT
1535 * supply an errno; a null errno implies that absolutely no further
1536 * writes are done to the journal (unless there are any already in
1537 * progress).
1538 *
1539 */
1540
1541void journal_abort(journal_t *journal, int errno)
1542{
1543        __journal_abort_soft(journal, errno);
1544}
1545
1546/**
1547 * int journal_errno () - returns the journal's error state.
1548 * @journal: journal to examine.
1549 *
1550 * This is the errno numbet set with journal_abort(), the last
1551 * time the journal was mounted - if the journal was stopped
1552 * without calling abort this will be 0.
1553 *
1554 * If the journal has been aborted on this mount time -EROFS will
1555 * be returned.
1556 */
1557int journal_errno(journal_t *journal)
1558{
1559        int err;
1560
1561        spin_lock(&journal->j_state_lock);
1562        if (journal->j_flags & JFS_ABORT)
1563                err = -EROFS;
1564        else
1565                err = journal->j_errno;
1566        spin_unlock(&journal->j_state_lock);
1567        return err;
1568}
1569
1570/**
1571 * int journal_clear_err () - clears the journal's error state
1572 * @journal: journal to act on.
1573 *
1574 * An error must be cleared or Acked to take a FS out of readonly
1575 * mode.
1576 */
1577int journal_clear_err(journal_t *journal)
1578{
1579        int err = 0;
1580
1581        spin_lock(&journal->j_state_lock);
1582        if (journal->j_flags & JFS_ABORT)
1583                err = -EROFS;
1584        else
1585                journal->j_errno = 0;
1586        spin_unlock(&journal->j_state_lock);
1587        return err;
1588}
1589
1590/**
1591 * void journal_ack_err() - Ack journal err.
1592 * @journal: journal to act on.
1593 *
1594 * An error must be cleared or Acked to take a FS out of readonly
1595 * mode.
1596 */
1597void journal_ack_err(journal_t *journal)
1598{
1599        spin_lock(&journal->j_state_lock);
1600        if (journal->j_errno)
1601                journal->j_flags |= JFS_ACK_ERR;
1602        spin_unlock(&journal->j_state_lock);
1603}
1604
1605int journal_blocks_per_page(struct inode *inode)
1606{
1607        return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1608}
1609
1610/*
1611 * Journal_head storage management
1612 */
1613static struct kmem_cache *journal_head_cache;
1614#ifdef CONFIG_JBD_DEBUG
1615static atomic_t nr_journal_heads = ATOMIC_INIT(0);
1616#endif
1617
1618static int journal_init_journal_head_cache(void)
1619{
1620        int retval;
1621
1622        J_ASSERT(journal_head_cache == 0);
1623        journal_head_cache = kmem_cache_create("journal_head",
1624                                sizeof(struct journal_head),
1625                                0,              /* offset */
1626                                SLAB_TEMPORARY, /* flags */
1627                                NULL);          /* ctor */
1628        retval = 0;
1629        if (journal_head_cache == 0) {
1630                retval = -ENOMEM;
1631                printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
1632        }
1633        return retval;
1634}
1635
1636static void journal_destroy_journal_head_cache(void)
1637{
1638        J_ASSERT(journal_head_cache != NULL);
1639        kmem_cache_destroy(journal_head_cache);
1640        journal_head_cache = NULL;
1641}
1642
1643/*
1644 * journal_head splicing and dicing
1645 */
1646static struct journal_head *journal_alloc_journal_head(void)
1647{
1648        struct journal_head *ret;
1649        static unsigned long last_warning;
1650
1651#ifdef CONFIG_JBD_DEBUG
1652        atomic_inc(&nr_journal_heads);
1653#endif
1654        ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
1655        if (ret == NULL) {
1656                jbd_debug(1, "out of memory for journal_head\n");
1657                if (time_after(jiffies, last_warning + 5*HZ)) {
1658                        printk(KERN_NOTICE "ENOMEM in %s, retrying.\n",
1659                               __FUNCTION__);
1660                        last_warning = jiffies;
1661                }
1662                while (ret == NULL) {
1663                        yield();
1664                        ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
1665                }
1666        }
1667        return ret;
1668}
1669
1670static void journal_free_journal_head(struct journal_head *jh)
1671{
1672#ifdef CONFIG_JBD_DEBUG
1673        atomic_dec(&nr_journal_heads);
1674        memset(jh, JBD_POISON_FREE, sizeof(*jh));
1675#endif
1676        kmem_cache_free(journal_head_cache, jh);
1677}
1678
1679/*
1680 * A journal_head is attached to a buffer_head whenever JBD has an
1681 * interest in the buffer.
1682 *
1683 * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
1684 * is set.  This bit is tested in core kernel code where we need to take
1685 * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
1686 * there.
1687 *
1688 * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
1689 *
1690 * When a buffer has its BH_JBD bit set it is immune from being released by
1691 * core kernel code, mainly via ->b_count.
1692 *
1693 * A journal_head may be detached from its buffer_head when the journal_head's
1694 * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL.
1695 * Various places in JBD call journal_remove_journal_head() to indicate that the
1696 * journal_head can be dropped if needed.
1697 *
1698 * Various places in the kernel want to attach a journal_head to a buffer_head
1699 * _before_ attaching the journal_head to a transaction.  To protect the
1700 * journal_head in this situation, journal_add_journal_head elevates the
1701 * journal_head's b_jcount refcount by one.  The caller must call
1702 * journal_put_journal_head() to undo this.
1703 *
1704 * So the typical usage would be:
1705 *
1706 *      (Attach a journal_head if needed.  Increments b_jcount)
1707 *      struct journal_head *jh = journal_add_journal_head(bh);
1708 *      ...
1709 *      jh->b_transaction = xxx;
1710 *      journal_put_journal_head(jh);
1711 *
1712 * Now, the journal_head's b_jcount is zero, but it is safe from being released
1713 * because it has a non-zero b_transaction.
1714 */
1715
1716/*
1717 * Give a buffer_head a journal_head.
1718 *
1719 * Doesn't need the journal lock.
1720 * May sleep.
1721 */
1722struct journal_head *journal_add_journal_head(struct buffer_head *bh)
1723{
1724        struct journal_head *jh;
1725        struct journal_head *new_jh = NULL;
1726
1727repeat:
1728        if (!buffer_jbd(bh)) {
1729                new_jh = journal_alloc_journal_head();
1730                memset(new_jh, 0, sizeof(*new_jh));
1731        }
1732
1733        jbd_lock_bh_journal_head(bh);
1734        if (buffer_jbd(bh)) {
1735                jh = bh2jh(bh);
1736        } else {
1737                J_ASSERT_BH(bh,
1738                        (atomic_read(&bh->b_count) > 0) ||
1739                        (bh->b_page && bh->b_page->mapping));
1740
1741                if (!new_jh) {
1742                        jbd_unlock_bh_journal_head(bh);
1743                        goto repeat;
1744                }
1745
1746                jh = new_jh;
1747                new_jh = NULL;          /* We consumed it */
1748                set_buffer_jbd(bh);
1749                bh->b_private = jh;
1750                jh->b_bh = bh;
1751                get_bh(bh);
1752                BUFFER_TRACE(bh, "added journal_head");
1753        }
1754        jh->b_jcount++;
1755        jbd_unlock_bh_journal_head(bh);
1756        if (new_jh)
1757                journal_free_journal_head(new_jh);
1758        return bh->b_private;
1759}
1760
1761/*
1762 * Grab a ref against this buffer_head's journal_head.  If it ended up not
1763 * having a journal_head, return NULL
1764 */
1765struct journal_head *journal_grab_journal_head(struct buffer_head *bh)
1766{
1767        struct journal_head *jh = NULL;
1768
1769        jbd_lock_bh_journal_head(bh);
1770        if (buffer_jbd(bh)) {
1771                jh = bh2jh(bh);
1772                jh->b_jcount++;
1773        }
1774        jbd_unlock_bh_journal_head(bh);
1775        return jh;
1776}
1777
1778static void __journal_remove_journal_head(struct buffer_head *bh)
1779{
1780        struct journal_head *jh = bh2jh(bh);
1781
1782        J_ASSERT_JH(jh, jh->b_jcount >= 0);
1783
1784        get_bh(bh);
1785        if (jh->b_jcount == 0) {
1786                if (jh->b_transaction == NULL &&
1787                                jh->b_next_transaction == NULL &&
1788                                jh->b_cp_transaction == NULL) {
1789                        J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
1790                        J_ASSERT_BH(bh, buffer_jbd(bh));
1791                        J_ASSERT_BH(bh, jh2bh(jh) == bh);
1792                        BUFFER_TRACE(bh, "remove journal_head");
1793                        if (jh->b_frozen_data) {
1794                                printk(KERN_WARNING "%s: freeing "
1795                                                "b_frozen_data\n",
1796                                                __FUNCTION__);
1797                                jbd_free(jh->b_frozen_data, bh->b_size);
1798                        }
1799                        if (jh->b_committed_data) {
1800                                printk(KERN_WARNING "%s: freeing "
1801                                                "b_committed_data\n",
1802                                                __FUNCTION__);
1803                                jbd_free(jh->b_committed_data, bh->b_size);
1804                        }
1805                        bh->b_private = NULL;
1806                        jh->b_bh = NULL;        /* debug, really */
1807                        clear_buffer_jbd(bh);
1808                        __brelse(bh);
1809                        journal_free_journal_head(jh);
1810                } else {
1811                        BUFFER_TRACE(bh, "journal_head was locked");
1812                }
1813        }
1814}
1815
1816/*
1817 * journal_remove_journal_head(): if the buffer isn't attached to a transaction
1818 * and has a zero b_jcount then remove and release its journal_head.   If we did
1819 * see that the buffer is not used by any transaction we also "logically"
1820 * decrement ->b_count.
1821 *
1822 * We in fact take an additional increment on ->b_count as a convenience,
1823 * because the caller usually wants to do additional things with the bh
1824 * after calling here.
1825 * The caller of journal_remove_journal_head() *must* run __brelse(bh) at some
1826 * time.  Once the caller has run __brelse(), the buffer is eligible for
1827 * reaping by try_to_free_buffers().
1828 */
1829void journal_remove_journal_head(struct buffer_head *bh)
1830{
1831        jbd_lock_bh_journal_head(bh);
1832        __journal_remove_journal_head(bh);
1833        jbd_unlock_bh_journal_head(bh);
1834}
1835
1836/*
1837 * Drop a reference on the passed journal_head.  If it fell to zero then try to
1838 * release the journal_head from the buffer_head.
1839 */
1840void journal_put_journal_head(struct journal_head *jh)
1841{
1842        struct buffer_head *bh = jh2bh(jh);
1843
1844        jbd_lock_bh_journal_head(bh);
1845        J_ASSERT_JH(jh, jh->b_jcount > 0);
1846        --jh->b_jcount;
1847        if (!jh->b_jcount && !jh->b_transaction) {
1848                __journal_remove_journal_head(bh);
1849                __brelse(bh);
1850        }
1851        jbd_unlock_bh_journal_head(bh);
1852}
1853
1854/*
1855 * debugfs tunables
1856 */
1857#ifdef CONFIG_JBD_DEBUG
1858
1859u8 journal_enable_debug __read_mostly;
1860EXPORT_SYMBOL(journal_enable_debug);
1861
1862static struct dentry *jbd_debugfs_dir;
1863static struct dentry *jbd_debug;
1864
1865static void __init jbd_create_debugfs_entry(void)
1866{
1867        jbd_debugfs_dir = debugfs_create_dir("jbd", NULL);
1868        if (jbd_debugfs_dir)
1869                jbd_debug = debugfs_create_u8("jbd-debug", S_IRUGO,
1870                                               jbd_debugfs_dir,
1871                                               &journal_enable_debug);
1872}
1873
1874static void __exit jbd_remove_debugfs_entry(void)
1875{
1876        debugfs_remove(jbd_debug);
1877        debugfs_remove(jbd_debugfs_dir);
1878}
1879
1880#else
1881
1882static inline void jbd_create_debugfs_entry(void)
1883{
1884}
1885
1886static inline void jbd_remove_debugfs_entry(void)
1887{
1888}
1889
1890#endif
1891
1892struct kmem_cache *jbd_handle_cache;
1893
1894static int __init journal_init_handle_cache(void)
1895{
1896        jbd_handle_cache = kmem_cache_create("journal_handle",
1897                                sizeof(handle_t),
1898                                0,              /* offset */
1899                                SLAB_TEMPORARY, /* flags */
1900                                NULL);          /* ctor */
1901        if (jbd_handle_cache == NULL) {
1902                printk(KERN_EMERG "JBD: failed to create handle cache\n");
1903                return -ENOMEM;
1904        }
1905        return 0;
1906}
1907
1908static void journal_destroy_handle_cache(void)
1909{
1910        if (jbd_handle_cache)
1911                kmem_cache_destroy(jbd_handle_cache);
1912}
1913
1914/*
1915 * Module startup and shutdown
1916 */
1917
1918static int __init journal_init_caches(void)
1919{
1920        int ret;
1921
1922        ret = journal_init_revoke_caches();
1923        if (ret == 0)
1924                ret = journal_init_journal_head_cache();
1925        if (ret == 0)
1926                ret = journal_init_handle_cache();
1927        return ret;
1928}
1929
1930static void journal_destroy_caches(void)
1931{
1932        journal_destroy_revoke_caches();
1933        journal_destroy_journal_head_cache();
1934        journal_destroy_handle_cache();
1935}
1936
1937static int __init journal_init(void)
1938{
1939        int ret;
1940
1941        BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
1942
1943        ret = journal_init_caches();
1944        if (ret != 0)
1945                journal_destroy_caches();
1946        jbd_create_debugfs_entry();
1947        return ret;
1948}
1949
1950static void __exit journal_exit(void)
1951{
1952#ifdef CONFIG_JBD_DEBUG
1953        int n = atomic_read(&nr_journal_heads);
1954        if (n)
1955                printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
1956#endif
1957        jbd_remove_debugfs_entry();
1958        journal_destroy_caches();
1959}
1960
1961MODULE_LICENSE("GPL");
1962module_init(journal_init);
1963module_exit(journal_exit);
1964
1965