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_abort);
  72EXPORT_SYMBOL(journal_errno);
  73EXPORT_SYMBOL(journal_ack_err);
  74EXPORT_SYMBOL(journal_clear_err);
  75EXPORT_SYMBOL(log_wait_commit);
  76EXPORT_SYMBOL(journal_start_commit);
  77EXPORT_SYMBOL(journal_force_commit_nested);
  78EXPORT_SYMBOL(journal_wipe);
  79EXPORT_SYMBOL(journal_blocks_per_page);
  80EXPORT_SYMBOL(journal_invalidatepage);
  81EXPORT_SYMBOL(journal_try_to_free_buffers);
  82EXPORT_SYMBOL(journal_force_commit);
  83
  84static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
  85static void __journal_abort_soft (journal_t *journal, int errno);
  86
  87/*
  88 * Helper function used to manage commit timeouts
  89 */
  90
  91static void commit_timeout(unsigned long __data)
  92{
  93        struct task_struct * p = (struct task_struct *) __data;
  94
  95        wake_up_process(p);
  96}
  97
  98/*
  99 * kjournald: The main thread function used to manage a logging device
 100 * journal.
 101 *
 102 * This kernel thread is responsible for two things:
 103 *
 104 * 1) COMMIT:  Every so often we need to commit the current state of the
 105 *    filesystem to disk.  The journal thread is responsible for writing
 106 *    all of the metadata buffers to disk.
 107 *
 108 * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
 109 *    of the data in that part of the log has been rewritten elsewhere on
 110 *    the disk.  Flushing these old buffers to reclaim space in the log is
 111 *    known as checkpointing, and this thread is responsible for that job.
 112 */
 113
 114static int kjournald(void *arg)
 115{
 116        journal_t *journal = arg;
 117        transaction_t *transaction;
 118
 119        /*
 120         * Set up an interval timer which can be used to trigger a commit wakeup
 121         * after the commit interval expires
 122         */
 123        setup_timer(&journal->j_commit_timer, commit_timeout,
 124                        (unsigned long)current);
 125
 126        /* Record that the journal thread is running */
 127        journal->j_task = current;
 128        wake_up(&journal->j_wait_done_commit);
 129
 130        printk(KERN_INFO "kjournald starting.  Commit interval %ld seconds\n",
 131                        journal->j_commit_interval / HZ);
 132
 133        /*
 134         * And now, wait forever for commit wakeup events.
 135         */
 136        spin_lock(&journal->j_state_lock);
 137
 138loop:
 139        if (journal->j_flags & JFS_UNMOUNT)
 140                goto end_loop;
 141
 142        jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
 143                journal->j_commit_sequence, journal->j_commit_request);
 144
 145        if (journal->j_commit_sequence != journal->j_commit_request) {
 146                jbd_debug(1, "OK, requests differ\n");
 147                spin_unlock(&journal->j_state_lock);
 148                del_timer_sync(&journal->j_commit_timer);
 149                journal_commit_transaction(journal);
 150                spin_lock(&journal->j_state_lock);
 151                goto loop;
 152        }
 153
 154        wake_up(&journal->j_wait_done_commit);
 155        if (freezing(current)) {
 156                /*
 157                 * The simpler the better. Flushing journal isn't a
 158                 * good idea, because that depends on threads that may
 159                 * be already stopped.
 160                 */
 161                jbd_debug(1, "Now suspending kjournald\n");
 162                spin_unlock(&journal->j_state_lock);
 163                refrigerator();
 164                spin_lock(&journal->j_state_lock);
 165        } else {
 166                /*
 167                 * We assume on resume that commits are already there,
 168                 * so we don't sleep
 169                 */
 170                DEFINE_WAIT(wait);
 171                int should_sleep = 1;
 172
 173                prepare_to_wait(&journal->j_wait_commit, &wait,
 174                                TASK_INTERRUPTIBLE);
 175                if (journal->j_commit_sequence != journal->j_commit_request)
 176                        should_sleep = 0;
 177                transaction = journal->j_running_transaction;
 178                if (transaction && time_after_eq(jiffies,
 179                                                transaction->t_expires))
 180                        should_sleep = 0;
 181                if (journal->j_flags & JFS_UNMOUNT)
 182                        should_sleep = 0;
 183                if (should_sleep) {
 184                        spin_unlock(&journal->j_state_lock);
 185                        schedule();
 186                        spin_lock(&journal->j_state_lock);
 187                }
 188                finish_wait(&journal->j_wait_commit, &wait);
 189        }
 190
 191        jbd_debug(1, "kjournald wakes\n");
 192
 193        /*
 194         * Were we woken up by a commit wakeup event?
 195         */
 196        transaction = journal->j_running_transaction;
 197        if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
 198                journal->j_commit_request = transaction->t_tid;
 199                jbd_debug(1, "woke because of timeout\n");
 200        }
 201        goto loop;
 202
 203end_loop:
 204        spin_unlock(&journal->j_state_lock);
 205        del_timer_sync(&journal->j_commit_timer);
 206        journal->j_task = NULL;
 207        wake_up(&journal->j_wait_done_commit);
 208        jbd_debug(1, "Journal thread exiting.\n");
 209        return 0;
 210}
 211
 212static int journal_start_thread(journal_t *journal)
 213{
 214        struct task_struct *t;
 215
 216        t = kthread_run(kjournald, journal, "kjournald");
 217        if (IS_ERR(t))
 218                return PTR_ERR(t);
 219
 220        wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
 221        return 0;
 222}
 223
 224static void journal_kill_thread(journal_t *journal)
 225{
 226        spin_lock(&journal->j_state_lock);
 227        journal->j_flags |= JFS_UNMOUNT;
 228
 229        while (journal->j_task) {
 230                wake_up(&journal->j_wait_commit);
 231                spin_unlock(&journal->j_state_lock);
 232                wait_event(journal->j_wait_done_commit,
 233                                journal->j_task == NULL);
 234                spin_lock(&journal->j_state_lock);
 235        }
 236        spin_unlock(&journal->j_state_lock);
 237}
 238
 239/*
 240 * journal_write_metadata_buffer: write a metadata buffer to the journal.
 241 *
 242 * Writes a metadata buffer to a given disk block.  The actual IO is not
 243 * performed but a new buffer_head is constructed which labels the data
 244 * to be written with the correct destination disk block.
 245 *
 246 * Any magic-number escaping which needs to be done will cause a
 247 * copy-out here.  If the buffer happens to start with the
 248 * JFS_MAGIC_NUMBER, then we can't write it to the log directly: the
 249 * magic number is only written to the log for descripter blocks.  In
 250 * this case, we copy the data and replace the first word with 0, and we
 251 * return a result code which indicates that this buffer needs to be
 252 * marked as an escaped buffer in the corresponding log descriptor
 253 * block.  The missing word can then be restored when the block is read
 254 * during recovery.
 255 *
 256 * If the source buffer has already been modified by a new transaction
 257 * since we took the last commit snapshot, we use the frozen copy of
 258 * that data for IO.  If we end up using the existing buffer_head's data
 259 * for the write, then we *have* to lock the buffer to prevent anyone
 260 * else from using and possibly modifying it while the IO is in
 261 * progress.
 262 *
 263 * The function returns a pointer to the buffer_heads to be used for IO.
 264 *
 265 * We assume that the journal has already been locked in this function.
 266 *
 267 * Return value:
 268 *  <0: Error
 269 * >=0: Finished OK
 270 *
 271 * On success:
 272 * Bit 0 set == escape performed on the data
 273 * Bit 1 set == buffer copy-out performed (kfree the data after IO)
 274 */
 275
 276int journal_write_metadata_buffer(transaction_t *transaction,
 277                                  struct journal_head  *jh_in,
 278                                  struct journal_head **jh_out,
 279                                  unsigned long blocknr)
 280{
 281        int need_copy_out = 0;
 282        int done_copy_out = 0;
 283        int do_escape = 0;
 284        char *mapped_data;
 285        struct buffer_head *new_bh;
 286        struct journal_head *new_jh;
 287        struct page *new_page;
 288        unsigned int new_offset;
 289        struct buffer_head *bh_in = jh2bh(jh_in);
 290
 291        /*
 292         * The buffer really shouldn't be locked: only the current committing
 293         * transaction is allowed to write it, so nobody else is allowed
 294         * to do any IO.
 295         *
 296         * akpm: except if we're journalling data, and write() output is
 297         * also part of a shared mapping, and another thread has
 298         * decided to launch a writepage() against this buffer.
 299         */
 300        J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
 301
 302        new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
 303
 304        /*
 305         * If a new transaction has already done a buffer copy-out, then
 306         * we use that version of the data for the commit.
 307         */
 308        jbd_lock_bh_state(bh_in);
 309repeat:
 310        if (jh_in->b_frozen_data) {
 311                done_copy_out = 1;
 312                new_page = virt_to_page(jh_in->b_frozen_data);
 313                new_offset = offset_in_page(jh_in->b_frozen_data);
 314        } else {
 315                new_page = jh2bh(jh_in)->b_page;
 316                new_offset = offset_in_page(jh2bh(jh_in)->b_data);
 317        }
 318
 319        mapped_data = kmap_atomic(new_page, KM_USER0);
 320        /*
 321         * Check for escaping
 322         */
 323        if (*((__be32 *)(mapped_data + new_offset)) ==
 324                                cpu_to_be32(JFS_MAGIC_NUMBER)) {
 325                need_copy_out = 1;
 326                do_escape = 1;
 327        }
 328        kunmap_atomic(mapped_data, KM_USER0);
 329
 330        /*
 331         * Do we need to do a data copy?
 332         */
 333        if (need_copy_out && !done_copy_out) {
 334                char *tmp;
 335
 336                jbd_unlock_bh_state(bh_in);
 337                tmp = jbd_alloc(bh_in->b_size, GFP_NOFS);
 338                jbd_lock_bh_state(bh_in);
 339                if (jh_in->b_frozen_data) {
 340                        jbd_free(tmp, bh_in->b_size);
 341                        goto repeat;
 342                }
 343
 344                jh_in->b_frozen_data = tmp;
 345                mapped_data = kmap_atomic(new_page, KM_USER0);
 346                memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
 347                kunmap_atomic(mapped_data, KM_USER0);
 348
 349                new_page = virt_to_page(tmp);
 350                new_offset = offset_in_page(tmp);
 351                done_copy_out = 1;
 352        }
 353
 354        /*
 355         * Did we need to do an escaping?  Now we've done all the
 356         * copying, we can finally do so.
 357         */
 358        if (do_escape) {
 359                mapped_data = kmap_atomic(new_page, KM_USER0);
 360                *((unsigned int *)(mapped_data + new_offset)) = 0;
 361                kunmap_atomic(mapped_data, KM_USER0);
 362        }
 363
 364        /* keep subsequent assertions sane */
 365        new_bh->b_state = 0;
 366        init_buffer(new_bh, NULL, NULL);
 367        atomic_set(&new_bh->b_count, 1);
 368        jbd_unlock_bh_state(bh_in);
 369
 370        new_jh = journal_add_journal_head(new_bh);      /* This sleeps */
 371
 372        set_bh_page(new_bh, new_page, new_offset);
 373        new_jh->b_transaction = NULL;
 374        new_bh->b_size = jh2bh(jh_in)->b_size;
 375        new_bh->b_bdev = transaction->t_journal->j_dev;
 376        new_bh->b_blocknr = blocknr;
 377        set_buffer_mapped(new_bh);
 378        set_buffer_dirty(new_bh);
 379
 380        *jh_out = new_jh;
 381
 382        /*
 383         * The to-be-written buffer needs to get moved to the io queue,
 384         * and the original buffer whose contents we are shadowing or
 385         * copying is moved to the transaction's shadow queue.
 386         */
 387        JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
 388        journal_file_buffer(jh_in, transaction, BJ_Shadow);
 389        JBUFFER_TRACE(new_jh, "file as BJ_IO");
 390        journal_file_buffer(new_jh, transaction, BJ_IO);
 391
 392        return do_escape | (done_copy_out << 1);
 393}
 394
 395/*
 396 * Allocation code for the journal file.  Manage the space left in the
 397 * journal, so that we can begin checkpointing when appropriate.
 398 */
 399
 400/*
 401 * __log_space_left: Return the number of free blocks left in the journal.
 402 *
 403 * Called with the journal already locked.
 404 *
 405 * Called under j_state_lock
 406 */
 407
 408int __log_space_left(journal_t *journal)
 409{
 410        int left = journal->j_free;
 411
 412        assert_spin_locked(&journal->j_state_lock);
 413
 414        /*
 415         * Be pessimistic here about the number of those free blocks which
 416         * might be required for log descriptor control blocks.
 417         */
 418
 419#define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
 420
 421        left -= MIN_LOG_RESERVED_BLOCKS;
 422
 423        if (left <= 0)
 424                return 0;
 425        left -= (left >> 3);
 426        return left;
 427}
 428
 429/*
 430 * Called under j_state_lock.  Returns true if a transaction was started.
 431 */
 432int __log_start_commit(journal_t *journal, tid_t target)
 433{
 434        /*
 435         * Are we already doing a recent enough commit?
 436         */
 437        if (!tid_geq(journal->j_commit_request, target)) {
 438                /*
 439                 * We want a new commit: OK, mark the request and wakup the
 440                 * commit thread.  We do _not_ do the commit ourselves.
 441                 */
 442
 443                journal->j_commit_request = target;
 444                jbd_debug(1, "JBD: requesting commit %d/%d\n",
 445                          journal->j_commit_request,
 446                          journal->j_commit_sequence);
 447                wake_up(&journal->j_wait_commit);
 448                return 1;
 449        }
 450        return 0;
 451}
 452
 453int log_start_commit(journal_t *journal, tid_t tid)
 454{
 455        int ret;
 456
 457        spin_lock(&journal->j_state_lock);
 458        ret = __log_start_commit(journal, tid);
 459        spin_unlock(&journal->j_state_lock);
 460        return ret;
 461}
 462
 463/*
 464 * Force and wait upon a commit if the calling process is not within
 465 * transaction.  This is used for forcing out undo-protected data which contains
 466 * bitmaps, when the fs is running out of space.
 467 *
 468 * We can only force the running transaction if we don't have an active handle;
 469 * otherwise, we will deadlock.
 470 *
 471 * Returns true if a transaction was started.
 472 */
 473int journal_force_commit_nested(journal_t *journal)
 474{
 475        transaction_t *transaction = NULL;
 476        tid_t tid;
 477
 478        spin_lock(&journal->j_state_lock);
 479        if (journal->j_running_transaction && !current->journal_info) {
 480                transaction = journal->j_running_transaction;
 481                __log_start_commit(journal, transaction->t_tid);
 482        } else if (journal->j_committing_transaction)
 483                transaction = journal->j_committing_transaction;
 484
 485        if (!transaction) {
 486                spin_unlock(&journal->j_state_lock);
 487                return 0;       /* Nothing to retry */
 488        }
 489
 490        tid = transaction->t_tid;
 491        spin_unlock(&journal->j_state_lock);
 492        log_wait_commit(journal, tid);
 493        return 1;
 494}
 495
 496/*
 497 * Start a commit of the current running transaction (if any).  Returns true
 498 * if a transaction was started, and fills its tid in at *ptid
 499 */
 500int journal_start_commit(journal_t *journal, tid_t *ptid)
 501{
 502        int ret = 0;
 503
 504        spin_lock(&journal->j_state_lock);
 505        if (journal->j_running_transaction) {
 506                tid_t tid = journal->j_running_transaction->t_tid;
 507
 508                ret = __log_start_commit(journal, tid);
 509                if (ret && ptid)
 510                        *ptid = tid;
 511        } else if (journal->j_committing_transaction && ptid) {
 512                /*
 513                 * If ext3_write_super() recently started a commit, then we
 514                 * have to wait for completion of that transaction
 515                 */
 516                *ptid = journal->j_committing_transaction->t_tid;
 517                ret = 1;
 518        }
 519        spin_unlock(&journal->j_state_lock);
 520        return ret;
 521}
 522
 523/*
 524 * Wait for a specified commit to complete.
 525 * The caller may not hold the journal lock.
 526 */
 527int log_wait_commit(journal_t *journal, tid_t tid)
 528{
 529        int err = 0;
 530
 531#ifdef CONFIG_JBD_DEBUG
 532        spin_lock(&journal->j_state_lock);
 533        if (!tid_geq(journal->j_commit_request, tid)) {
 534                printk(KERN_EMERG
 535                       "%s: error: j_commit_request=%d, tid=%d\n",
 536                       __func__, journal->j_commit_request, tid);
 537        }
 538        spin_unlock(&journal->j_state_lock);
 539#endif
 540        spin_lock(&journal->j_state_lock);
 541        while (tid_gt(tid, journal->j_commit_sequence)) {
 542                jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
 543                                  tid, journal->j_commit_sequence);
 544                wake_up(&journal->j_wait_commit);
 545                spin_unlock(&journal->j_state_lock);
 546                wait_event(journal->j_wait_done_commit,
 547                                !tid_gt(tid, journal->j_commit_sequence));
 548                spin_lock(&journal->j_state_lock);
 549        }
 550        spin_unlock(&journal->j_state_lock);
 551
 552        if (unlikely(is_journal_aborted(journal))) {
 553                printk(KERN_EMERG "journal commit I/O error\n");
 554                err = -EIO;
 555        }
 556        return err;
 557}
 558
 559/*
 560 * Log buffer allocation routines:
 561 */
 562
 563int journal_next_log_block(journal_t *journal, unsigned long *retp)
 564{
 565        unsigned long blocknr;
 566
 567        spin_lock(&journal->j_state_lock);
 568        J_ASSERT(journal->j_free > 1);
 569
 570        blocknr = journal->j_head;
 571        journal->j_head++;
 572        journal->j_free--;
 573        if (journal->j_head == journal->j_last)
 574                journal->j_head = journal->j_first;
 575        spin_unlock(&journal->j_state_lock);
 576        return journal_bmap(journal, blocknr, retp);
 577}
 578
 579/*
 580 * Conversion of logical to physical block numbers for the journal
 581 *
 582 * On external journals the journal blocks are identity-mapped, so
 583 * this is a no-op.  If needed, we can use j_blk_offset - everything is
 584 * ready.
 585 */
 586int journal_bmap(journal_t *journal, unsigned long blocknr,
 587                 unsigned long *retp)
 588{
 589        int err = 0;
 590        unsigned long ret;
 591
 592        if (journal->j_inode) {
 593                ret = bmap(journal->j_inode, blocknr);
 594                if (ret)
 595                        *retp = ret;
 596                else {
 597                        char b[BDEVNAME_SIZE];
 598
 599                        printk(KERN_ALERT "%s: journal block not found "
 600                                        "at offset %lu on %s\n",
 601                                __func__,
 602                                blocknr,
 603                                bdevname(journal->j_dev, b));
 604                        err = -EIO;
 605                        __journal_abort_soft(journal, err);
 606                }
 607        } else {
 608                *retp = blocknr; /* +journal->j_blk_offset */
 609        }
 610        return err;
 611}
 612
 613/*
 614 * We play buffer_head aliasing tricks to write data/metadata blocks to
 615 * the journal without copying their contents, but for journal
 616 * descriptor blocks we do need to generate bona fide buffers.
 617 *
 618 * After the caller of journal_get_descriptor_buffer() has finished modifying
 619 * the buffer's contents they really should run flush_dcache_page(bh->b_page).
 620 * But we don't bother doing that, so there will be coherency problems with
 621 * mmaps of blockdevs which hold live JBD-controlled filesystems.
 622 */
 623struct journal_head *journal_get_descriptor_buffer(journal_t *journal)
 624{
 625        struct buffer_head *bh;
 626        unsigned long blocknr;
 627        int err;
 628
 629        err = journal_next_log_block(journal, &blocknr);
 630
 631        if (err)
 632                return NULL;
 633
 634        bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 635        lock_buffer(bh);
 636        memset(bh->b_data, 0, journal->j_blocksize);
 637        set_buffer_uptodate(bh);
 638        unlock_buffer(bh);
 639        BUFFER_TRACE(bh, "return this buffer");
 640        return journal_add_journal_head(bh);
 641}
 642
 643/*
 644 * Management for journal control blocks: functions to create and
 645 * destroy journal_t structures, and to initialise and read existing
 646 * journal blocks from disk.  */
 647
 648/* First: create and setup a journal_t object in memory.  We initialise
 649 * very few fields yet: that has to wait until we have created the
 650 * journal structures from from scratch, or loaded them from disk. */
 651
 652static journal_t * journal_init_common (void)
 653{
 654        journal_t *journal;
 655        int err;
 656
 657        journal = kzalloc(sizeof(*journal), GFP_KERNEL);
 658        if (!journal)
 659                goto fail;
 660
 661        init_waitqueue_head(&journal->j_wait_transaction_locked);
 662        init_waitqueue_head(&journal->j_wait_logspace);
 663        init_waitqueue_head(&journal->j_wait_done_commit);
 664        init_waitqueue_head(&journal->j_wait_checkpoint);
 665        init_waitqueue_head(&journal->j_wait_commit);
 666        init_waitqueue_head(&journal->j_wait_updates);
 667        mutex_init(&journal->j_barrier);
 668        mutex_init(&journal->j_checkpoint_mutex);
 669        spin_lock_init(&journal->j_revoke_lock);
 670        spin_lock_init(&journal->j_list_lock);
 671        spin_lock_init(&journal->j_state_lock);
 672
 673        journal->j_commit_interval = (HZ * JBD_DEFAULT_MAX_COMMIT_AGE);
 674
 675        /* The journal is marked for error until we succeed with recovery! */
 676        journal->j_flags = JFS_ABORT;
 677
 678        /* Set up a default-sized revoke table for the new mount. */
 679        err = journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
 680        if (err) {
 681                kfree(journal);
 682                goto fail;
 683        }
 684        return journal;
 685fail:
 686        return NULL;
 687}
 688
 689/* journal_init_dev and journal_init_inode:
 690 *
 691 * Create a journal structure assigned some fixed set of disk blocks to
 692 * the journal.  We don't actually touch those disk blocks yet, but we
 693 * need to set up all of the mapping information to tell the journaling
 694 * system where the journal blocks are.
 695 *
 696 */
 697
 698/**
 699 *  journal_t * journal_init_dev() - creates and initialises a journal structure
 700 *  @bdev: Block device on which to create the journal
 701 *  @fs_dev: Device which hold journalled filesystem for this journal.
 702 *  @start: Block nr Start of journal.
 703 *  @len:  Length of the journal in blocks.
 704 *  @blocksize: blocksize of journalling device
 705 *
 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                        __func__);
 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                        __func__);
 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                       __func__);
 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                       __func__);
 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 * Return <0 if we couldn't clean up the journal.
1125 */
1126int journal_destroy(journal_t *journal)
1127{
1128        int err = 0;
1129
1130        /* Wait for the commit thread to wake up and die. */
1131        journal_kill_thread(journal);
1132
1133        /* Force a final log commit */
1134        if (journal->j_running_transaction)
1135                journal_commit_transaction(journal);
1136
1137        /* Force any old transactions to disk */
1138
1139        /* Totally anal locking here... */
1140        spin_lock(&journal->j_list_lock);
1141        while (journal->j_checkpoint_transactions != NULL) {
1142                spin_unlock(&journal->j_list_lock);
1143                log_do_checkpoint(journal);
1144                spin_lock(&journal->j_list_lock);
1145        }
1146
1147        J_ASSERT(journal->j_running_transaction == NULL);
1148        J_ASSERT(journal->j_committing_transaction == NULL);
1149        J_ASSERT(journal->j_checkpoint_transactions == NULL);
1150        spin_unlock(&journal->j_list_lock);
1151
1152        if (journal->j_sb_buffer) {
1153                if (!is_journal_aborted(journal)) {
1154                        /* We can now mark the journal as empty. */
1155                        journal->j_tail = 0;
1156                        journal->j_tail_sequence =
1157                                ++journal->j_transaction_sequence;
1158                        journal_update_superblock(journal, 1);
1159                } else {
1160                        err = -EIO;
1161                }
1162                brelse(journal->j_sb_buffer);
1163        }
1164
1165        if (journal->j_inode)
1166                iput(journal->j_inode);
1167        if (journal->j_revoke)
1168                journal_destroy_revoke(journal);
1169        kfree(journal->j_wbuf);
1170        kfree(journal);
1171
1172        return err;
1173}
1174
1175
1176/**
1177 *int journal_check_used_features () - Check if features specified are used.
1178 * @journal: Journal to check.
1179 * @compat: bitmask of compatible features
1180 * @ro: bitmask of features that force read-only mount
1181 * @incompat: bitmask of incompatible features
1182 *
1183 * Check whether the journal uses all of a given set of
1184 * features.  Return true (non-zero) if it does.
1185 **/
1186
1187int journal_check_used_features (journal_t *journal, unsigned long compat,
1188                                 unsigned long ro, unsigned long incompat)
1189{
1190        journal_superblock_t *sb;
1191
1192        if (!compat && !ro && !incompat)
1193                return 1;
1194        if (journal->j_format_version == 1)
1195                return 0;
1196
1197        sb = journal->j_superblock;
1198
1199        if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1200            ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1201            ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1202                return 1;
1203
1204        return 0;
1205}
1206
1207/**
1208 * int journal_check_available_features() - Check feature set in journalling layer
1209 * @journal: Journal to check.
1210 * @compat: bitmask of compatible features
1211 * @ro: bitmask of features that force read-only mount
1212 * @incompat: bitmask of incompatible features
1213 *
1214 * Check whether the journaling code supports the use of
1215 * all of a given set of features on this journal.  Return true
1216 * (non-zero) if it can. */
1217
1218int journal_check_available_features (journal_t *journal, unsigned long compat,
1219                                      unsigned long ro, unsigned long incompat)
1220{
1221        journal_superblock_t *sb;
1222
1223        if (!compat && !ro && !incompat)
1224                return 1;
1225
1226        sb = journal->j_superblock;
1227
1228        /* We can support any known requested features iff the
1229         * superblock is in version 2.  Otherwise we fail to support any
1230         * extended sb features. */
1231
1232        if (journal->j_format_version != 2)
1233                return 0;
1234
1235        if ((compat   & JFS_KNOWN_COMPAT_FEATURES) == compat &&
1236            (ro       & JFS_KNOWN_ROCOMPAT_FEATURES) == ro &&
1237            (incompat & JFS_KNOWN_INCOMPAT_FEATURES) == incompat)
1238                return 1;
1239
1240        return 0;
1241}
1242
1243/**
1244 * int journal_set_features () - Mark a given journal feature in the superblock
1245 * @journal: Journal to act on.
1246 * @compat: bitmask of compatible features
1247 * @ro: bitmask of features that force read-only mount
1248 * @incompat: bitmask of incompatible features
1249 *
1250 * Mark a given journal feature as present on the
1251 * superblock.  Returns true if the requested features could be set.
1252 *
1253 */
1254
1255int journal_set_features (journal_t *journal, unsigned long compat,
1256                          unsigned long ro, unsigned long incompat)
1257{
1258        journal_superblock_t *sb;
1259
1260        if (journal_check_used_features(journal, compat, ro, incompat))
1261                return 1;
1262
1263        if (!journal_check_available_features(journal, compat, ro, incompat))
1264                return 0;
1265
1266        jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1267                  compat, ro, incompat);
1268
1269        sb = journal->j_superblock;
1270
1271        sb->s_feature_compat    |= cpu_to_be32(compat);
1272        sb->s_feature_ro_compat |= cpu_to_be32(ro);
1273        sb->s_feature_incompat  |= cpu_to_be32(incompat);
1274
1275        return 1;
1276}
1277
1278
1279/**
1280 * int journal_update_format () - Update on-disk journal structure.
1281 * @journal: Journal to act on.
1282 *
1283 * Given an initialised but unloaded journal struct, poke about in the
1284 * on-disk structure to update it to the most recent supported version.
1285 */
1286int journal_update_format (journal_t *journal)
1287{
1288        journal_superblock_t *sb;
1289        int err;
1290
1291        err = journal_get_superblock(journal);
1292        if (err)
1293                return err;
1294
1295        sb = journal->j_superblock;
1296
1297        switch (be32_to_cpu(sb->s_header.h_blocktype)) {
1298        case JFS_SUPERBLOCK_V2:
1299                return 0;
1300        case JFS_SUPERBLOCK_V1:
1301                return journal_convert_superblock_v1(journal, sb);
1302        default:
1303                break;
1304        }
1305        return -EINVAL;
1306}
1307
1308static int journal_convert_superblock_v1(journal_t *journal,
1309                                         journal_superblock_t *sb)
1310{
1311        int offset, blocksize;
1312        struct buffer_head *bh;
1313
1314        printk(KERN_WARNING
1315                "JBD: Converting superblock from version 1 to 2.\n");
1316
1317        /* Pre-initialise new fields to zero */
1318        offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb);
1319        blocksize = be32_to_cpu(sb->s_blocksize);
1320        memset(&sb->s_feature_compat, 0, blocksize-offset);
1321
1322        sb->s_nr_users = cpu_to_be32(1);
1323        sb->s_header.h_blocktype = cpu_to_be32(JFS_SUPERBLOCK_V2);
1324        journal->j_format_version = 2;
1325
1326        bh = journal->j_sb_buffer;
1327        BUFFER_TRACE(bh, "marking dirty");
1328        mark_buffer_dirty(bh);
1329        sync_dirty_buffer(bh);
1330        return 0;
1331}
1332
1333
1334/**
1335 * int journal_flush () - Flush journal
1336 * @journal: Journal to act on.
1337 *
1338 * Flush all data for a given journal to disk and empty the journal.
1339 * Filesystems can use this when remounting readonly to ensure that
1340 * recovery does not need to happen on remount.
1341 */
1342
1343int journal_flush(journal_t *journal)
1344{
1345        int err = 0;
1346        transaction_t *transaction = NULL;
1347        unsigned long old_tail;
1348
1349        spin_lock(&journal->j_state_lock);
1350
1351        /* Force everything buffered to the log... */
1352        if (journal->j_running_transaction) {
1353                transaction = journal->j_running_transaction;
1354                __log_start_commit(journal, transaction->t_tid);
1355        } else if (journal->j_committing_transaction)
1356                transaction = journal->j_committing_transaction;
1357
1358        /* Wait for the log commit to complete... */
1359        if (transaction) {
1360                tid_t tid = transaction->t_tid;
1361
1362                spin_unlock(&journal->j_state_lock);
1363                log_wait_commit(journal, tid);
1364        } else {
1365                spin_unlock(&journal->j_state_lock);
1366        }
1367
1368        /* ...and flush everything in the log out to disk. */
1369        spin_lock(&journal->j_list_lock);
1370        while (!err && journal->j_checkpoint_transactions != NULL) {
1371                spin_unlock(&journal->j_list_lock);
1372                mutex_lock(&journal->j_checkpoint_mutex);
1373                err = log_do_checkpoint(journal);
1374                mutex_unlock(&journal->j_checkpoint_mutex);
1375                spin_lock(&journal->j_list_lock);
1376        }
1377        spin_unlock(&journal->j_list_lock);
1378
1379        if (is_journal_aborted(journal))
1380                return -EIO;
1381
1382        cleanup_journal_tail(journal);
1383
1384        /* Finally, mark the journal as really needing no recovery.
1385         * This sets s_start==0 in the underlying superblock, which is
1386         * the magic code for a fully-recovered superblock.  Any future
1387         * commits of data to the journal will restore the current
1388         * s_start value. */
1389        spin_lock(&journal->j_state_lock);
1390        old_tail = journal->j_tail;
1391        journal->j_tail = 0;
1392        spin_unlock(&journal->j_state_lock);
1393        journal_update_superblock(journal, 1);
1394        spin_lock(&journal->j_state_lock);
1395        journal->j_tail = old_tail;
1396
1397        J_ASSERT(!journal->j_running_transaction);
1398        J_ASSERT(!journal->j_committing_transaction);
1399        J_ASSERT(!journal->j_checkpoint_transactions);
1400        J_ASSERT(journal->j_head == journal->j_tail);
1401        J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1402        spin_unlock(&journal->j_state_lock);
1403        return 0;
1404}
1405
1406/**
1407 * int journal_wipe() - Wipe journal contents
1408 * @journal: Journal to act on.
1409 * @write: flag (see below)
1410 *
1411 * Wipe out all of the contents of a journal, safely.  This will produce
1412 * a warning if the journal contains any valid recovery information.
1413 * Must be called between journal_init_*() and journal_load().
1414 *
1415 * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
1416 * we merely suppress recovery.
1417 */
1418
1419int journal_wipe(journal_t *journal, int write)
1420{
1421        journal_superblock_t *sb;
1422        int err = 0;
1423
1424        J_ASSERT (!(journal->j_flags & JFS_LOADED));
1425
1426        err = load_superblock(journal);
1427        if (err)
1428                return err;
1429
1430        sb = journal->j_superblock;
1431
1432        if (!journal->j_tail)
1433                goto no_recovery;
1434
1435        printk (KERN_WARNING "JBD: %s recovery information on journal\n",
1436                write ? "Clearing" : "Ignoring");
1437
1438        err = journal_skip_recovery(journal);
1439        if (write)
1440                journal_update_superblock(journal, 1);
1441
1442 no_recovery:
1443        return err;
1444}
1445
1446/*
1447 * journal_dev_name: format a character string to describe on what
1448 * device this journal is present.
1449 */
1450
1451static const char *journal_dev_name(journal_t *journal, char *buffer)
1452{
1453        struct block_device *bdev;
1454
1455        if (journal->j_inode)
1456                bdev = journal->j_inode->i_sb->s_bdev;
1457        else
1458                bdev = journal->j_dev;
1459
1460        return bdevname(bdev, buffer);
1461}
1462
1463/*
1464 * Journal abort has very specific semantics, which we describe
1465 * for journal abort.
1466 *
1467 * Two internal function, which provide abort to te jbd layer
1468 * itself are here.
1469 */
1470
1471/*
1472 * Quick version for internal journal use (doesn't lock the journal).
1473 * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
1474 * and don't attempt to make any other journal updates.
1475 */
1476static void __journal_abort_hard(journal_t *journal)
1477{
1478        transaction_t *transaction;
1479        char b[BDEVNAME_SIZE];
1480
1481        if (journal->j_flags & JFS_ABORT)
1482                return;
1483
1484        printk(KERN_ERR "Aborting journal on device %s.\n",
1485                journal_dev_name(journal, b));
1486
1487        spin_lock(&journal->j_state_lock);
1488        journal->j_flags |= JFS_ABORT;
1489        transaction = journal->j_running_transaction;
1490        if (transaction)
1491                __log_start_commit(journal, transaction->t_tid);
1492        spin_unlock(&journal->j_state_lock);
1493}
1494
1495/* Soft abort: record the abort error status in the journal superblock,
1496 * but don't do any other IO. */
1497static void __journal_abort_soft (journal_t *journal, int errno)
1498{
1499        if (journal->j_flags & JFS_ABORT)
1500                return;
1501
1502        if (!journal->j_errno)
1503                journal->j_errno = errno;
1504
1505        __journal_abort_hard(journal);
1506
1507        if (errno)
1508                journal_update_superblock(journal, 1);
1509}
1510
1511/**
1512 * void journal_abort () - Shutdown the journal immediately.
1513 * @journal: the journal to shutdown.
1514 * @errno:   an error number to record in the journal indicating
1515 *           the reason for the shutdown.
1516 *
1517 * Perform a complete, immediate shutdown of the ENTIRE
1518 * journal (not of a single transaction).  This operation cannot be
1519 * undone without closing and reopening the journal.
1520 *
1521 * The journal_abort function is intended to support higher level error
1522 * recovery mechanisms such as the ext2/ext3 remount-readonly error
1523 * mode.
1524 *
1525 * Journal abort has very specific semantics.  Any existing dirty,
1526 * unjournaled buffers in the main filesystem will still be written to
1527 * disk by bdflush, but the journaling mechanism will be suspended
1528 * immediately and no further transaction commits will be honoured.
1529 *
1530 * Any dirty, journaled buffers will be written back to disk without
1531 * hitting the journal.  Atomicity cannot be guaranteed on an aborted
1532 * filesystem, but we _do_ attempt to leave as much data as possible
1533 * behind for fsck to use for cleanup.
1534 *
1535 * Any attempt to get a new transaction handle on a journal which is in
1536 * ABORT state will just result in an -EROFS error return.  A
1537 * journal_stop on an existing handle will return -EIO if we have
1538 * entered abort state during the update.
1539 *
1540 * Recursive transactions are not disturbed by journal abort until the
1541 * final journal_stop, which will receive the -EIO error.
1542 *
1543 * Finally, the journal_abort call allows the caller to supply an errno
1544 * which will be recorded (if possible) in the journal superblock.  This
1545 * allows a client to record failure conditions in the middle of a
1546 * transaction without having to complete the transaction to record the
1547 * failure to disk.  ext3_error, for example, now uses this
1548 * functionality.
1549 *
1550 * Errors which originate from within the journaling layer will NOT
1551 * supply an errno; a null errno implies that absolutely no further
1552 * writes are done to the journal (unless there are any already in
1553 * progress).
1554 *
1555 */
1556
1557void journal_abort(journal_t *journal, int errno)
1558{
1559        __journal_abort_soft(journal, errno);
1560}
1561
1562/**
1563 * int journal_errno () - returns the journal's error state.
1564 * @journal: journal to examine.
1565 *
1566 * This is the errno numbet set with journal_abort(), the last
1567 * time the journal was mounted - if the journal was stopped
1568 * without calling abort this will be 0.
1569 *
1570 * If the journal has been aborted on this mount time -EROFS will
1571 * be returned.
1572 */
1573int journal_errno(journal_t *journal)
1574{
1575        int err;
1576
1577        spin_lock(&journal->j_state_lock);
1578        if (journal->j_flags & JFS_ABORT)
1579                err = -EROFS;
1580        else
1581                err = journal->j_errno;
1582        spin_unlock(&journal->j_state_lock);
1583        return err;
1584}
1585
1586/**
1587 * int journal_clear_err () - clears the journal's error state
1588 * @journal: journal to act on.
1589 *
1590 * An error must be cleared or Acked to take a FS out of readonly
1591 * mode.
1592 */
1593int journal_clear_err(journal_t *journal)
1594{
1595        int err = 0;
1596
1597        spin_lock(&journal->j_state_lock);
1598        if (journal->j_flags & JFS_ABORT)
1599                err = -EROFS;
1600        else
1601                journal->j_errno = 0;
1602        spin_unlock(&journal->j_state_lock);
1603        return err;
1604}
1605
1606/**
1607 * void journal_ack_err() - Ack journal err.
1608 * @journal: journal to act on.
1609 *
1610 * An error must be cleared or Acked to take a FS out of readonly
1611 * mode.
1612 */
1613void journal_ack_err(journal_t *journal)
1614{
1615        spin_lock(&journal->j_state_lock);
1616        if (journal->j_errno)
1617                journal->j_flags |= JFS_ACK_ERR;
1618        spin_unlock(&journal->j_state_lock);
1619}
1620
1621int journal_blocks_per_page(struct inode *inode)
1622{
1623        return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1624}
1625
1626/*
1627 * Journal_head storage management
1628 */
1629static struct kmem_cache *journal_head_cache;
1630#ifdef CONFIG_JBD_DEBUG
1631static atomic_t nr_journal_heads = ATOMIC_INIT(0);
1632#endif
1633
1634static int journal_init_journal_head_cache(void)
1635{
1636        int retval;
1637
1638        J_ASSERT(journal_head_cache == NULL);
1639        journal_head_cache = kmem_cache_create("journal_head",
1640                                sizeof(struct journal_head),
1641                                0,              /* offset */
1642                                SLAB_TEMPORARY, /* flags */
1643                                NULL);          /* ctor */
1644        retval = 0;
1645        if (!journal_head_cache) {
1646                retval = -ENOMEM;
1647                printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
1648        }
1649        return retval;
1650}
1651
1652static void journal_destroy_journal_head_cache(void)
1653{
1654        if (journal_head_cache) {
1655                kmem_cache_destroy(journal_head_cache);
1656                journal_head_cache = NULL;
1657        }
1658}
1659
1660/*
1661 * journal_head splicing and dicing
1662 */
1663static struct journal_head *journal_alloc_journal_head(void)
1664{
1665        struct journal_head *ret;
1666        static unsigned long last_warning;
1667
1668#ifdef CONFIG_JBD_DEBUG
1669        atomic_inc(&nr_journal_heads);
1670#endif
1671        ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
1672        if (ret == NULL) {
1673                jbd_debug(1, "out of memory for journal_head\n");
1674                if (time_after(jiffies, last_warning + 5*HZ)) {
1675                        printk(KERN_NOTICE "ENOMEM in %s, retrying.\n",
1676                               __func__);
1677                        last_warning = jiffies;
1678                }
1679                while (ret == NULL) {
1680                        yield();
1681                        ret = kmem_cache_alloc(journal_head_cache, GFP_NOFS);
1682                }
1683        }
1684        return ret;
1685}
1686
1687static void journal_free_journal_head(struct journal_head *jh)
1688{
1689#ifdef CONFIG_JBD_DEBUG
1690        atomic_dec(&nr_journal_heads);
1691        memset(jh, JBD_POISON_FREE, sizeof(*jh));
1692#endif
1693        kmem_cache_free(journal_head_cache, jh);
1694}
1695
1696/*
1697 * A journal_head is attached to a buffer_head whenever JBD has an
1698 * interest in the buffer.
1699 *
1700 * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
1701 * is set.  This bit is tested in core kernel code where we need to take
1702 * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
1703 * there.
1704 *
1705 * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
1706 *
1707 * When a buffer has its BH_JBD bit set it is immune from being released by
1708 * core kernel code, mainly via ->b_count.
1709 *
1710 * A journal_head may be detached from its buffer_head when the journal_head's
1711 * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL.
1712 * Various places in JBD call journal_remove_journal_head() to indicate that the
1713 * journal_head can be dropped if needed.
1714 *
1715 * Various places in the kernel want to attach a journal_head to a buffer_head
1716 * _before_ attaching the journal_head to a transaction.  To protect the
1717 * journal_head in this situation, journal_add_journal_head elevates the
1718 * journal_head's b_jcount refcount by one.  The caller must call
1719 * journal_put_journal_head() to undo this.
1720 *
1721 * So the typical usage would be:
1722 *
1723 *      (Attach a journal_head if needed.  Increments b_jcount)
1724 *      struct journal_head *jh = journal_add_journal_head(bh);
1725 *      ...
1726 *      jh->b_transaction = xxx;
1727 *      journal_put_journal_head(jh);
1728 *
1729 * Now, the journal_head's b_jcount is zero, but it is safe from being released
1730 * because it has a non-zero b_transaction.
1731 */
1732
1733/*
1734 * Give a buffer_head a journal_head.
1735 *
1736 * Doesn't need the journal lock.
1737 * May sleep.
1738 */
1739struct journal_head *journal_add_journal_head(struct buffer_head *bh)
1740{
1741        struct journal_head *jh;
1742        struct journal_head *new_jh = NULL;
1743
1744repeat:
1745        if (!buffer_jbd(bh)) {
1746                new_jh = journal_alloc_journal_head();
1747                memset(new_jh, 0, sizeof(*new_jh));
1748        }
1749
1750        jbd_lock_bh_journal_head(bh);
1751        if (buffer_jbd(bh)) {
1752                jh = bh2jh(bh);
1753        } else {
1754                J_ASSERT_BH(bh,
1755                        (atomic_read(&bh->b_count) > 0) ||
1756                        (bh->b_page && bh->b_page->mapping));
1757
1758                if (!new_jh) {
1759                        jbd_unlock_bh_journal_head(bh);
1760                        goto repeat;
1761                }
1762
1763                jh = new_jh;
1764                new_jh = NULL;          /* We consumed it */
1765                set_buffer_jbd(bh);
1766                bh->b_private = jh;
1767                jh->b_bh = bh;
1768                get_bh(bh);
1769                BUFFER_TRACE(bh, "added journal_head");
1770        }
1771        jh->b_jcount++;
1772        jbd_unlock_bh_journal_head(bh);
1773        if (new_jh)
1774                journal_free_journal_head(new_jh);
1775        return bh->b_private;
1776}
1777
1778/*
1779 * Grab a ref against this buffer_head's journal_head.  If it ended up not
1780 * having a journal_head, return NULL
1781 */
1782struct journal_head *journal_grab_journal_head(struct buffer_head *bh)
1783{
1784        struct journal_head *jh = NULL;
1785
1786        jbd_lock_bh_journal_head(bh);
1787        if (buffer_jbd(bh)) {
1788                jh = bh2jh(bh);
1789                jh->b_jcount++;
1790        }
1791        jbd_unlock_bh_journal_head(bh);
1792        return jh;
1793}
1794
1795static void __journal_remove_journal_head(struct buffer_head *bh)
1796{
1797        struct journal_head *jh = bh2jh(bh);
1798
1799        J_ASSERT_JH(jh, jh->b_jcount >= 0);
1800
1801        get_bh(bh);
1802        if (jh->b_jcount == 0) {
1803                if (jh->b_transaction == NULL &&
1804                                jh->b_next_transaction == NULL &&
1805                                jh->b_cp_transaction == NULL) {
1806                        J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
1807                        J_ASSERT_BH(bh, buffer_jbd(bh));
1808                        J_ASSERT_BH(bh, jh2bh(jh) == bh);
1809                        BUFFER_TRACE(bh, "remove journal_head");
1810                        if (jh->b_frozen_data) {
1811                                printk(KERN_WARNING "%s: freeing "
1812                                                "b_frozen_data\n",
1813                                                __func__);
1814                                jbd_free(jh->b_frozen_data, bh->b_size);
1815                        }
1816                        if (jh->b_committed_data) {
1817                                printk(KERN_WARNING "%s: freeing "
1818                                                "b_committed_data\n",
1819                                                __func__);
1820                                jbd_free(jh->b_committed_data, bh->b_size);
1821                        }
1822                        bh->b_private = NULL;
1823                        jh->b_bh = NULL;        /* debug, really */
1824                        clear_buffer_jbd(bh);
1825                        __brelse(bh);
1826                        journal_free_journal_head(jh);
1827                } else {
1828                        BUFFER_TRACE(bh, "journal_head was locked");
1829                }
1830        }
1831}
1832
1833/*
1834 * journal_remove_journal_head(): if the buffer isn't attached to a transaction
1835 * and has a zero b_jcount then remove and release its journal_head.   If we did
1836 * see that the buffer is not used by any transaction we also "logically"
1837 * decrement ->b_count.
1838 *
1839 * We in fact take an additional increment on ->b_count as a convenience,
1840 * because the caller usually wants to do additional things with the bh
1841 * after calling here.
1842 * The caller of journal_remove_journal_head() *must* run __brelse(bh) at some
1843 * time.  Once the caller has run __brelse(), the buffer is eligible for
1844 * reaping by try_to_free_buffers().
1845 */
1846void journal_remove_journal_head(struct buffer_head *bh)
1847{
1848        jbd_lock_bh_journal_head(bh);
1849        __journal_remove_journal_head(bh);
1850        jbd_unlock_bh_journal_head(bh);
1851}
1852
1853/*
1854 * Drop a reference on the passed journal_head.  If it fell to zero then try to
1855 * release the journal_head from the buffer_head.
1856 */
1857void journal_put_journal_head(struct journal_head *jh)
1858{
1859        struct buffer_head *bh = jh2bh(jh);
1860
1861        jbd_lock_bh_journal_head(bh);
1862        J_ASSERT_JH(jh, jh->b_jcount > 0);
1863        --jh->b_jcount;
1864        if (!jh->b_jcount && !jh->b_transaction) {
1865                __journal_remove_journal_head(bh);
1866                __brelse(bh);
1867        }
1868        jbd_unlock_bh_journal_head(bh);
1869}
1870
1871/*
1872 * debugfs tunables
1873 */
1874#ifdef CONFIG_JBD_DEBUG
1875
1876u8 journal_enable_debug __read_mostly;
1877EXPORT_SYMBOL(journal_enable_debug);
1878
1879static struct dentry *jbd_debugfs_dir;
1880static struct dentry *jbd_debug;
1881
1882static void __init jbd_create_debugfs_entry(void)
1883{
1884        jbd_debugfs_dir = debugfs_create_dir("jbd", NULL);
1885        if (jbd_debugfs_dir)
1886                jbd_debug = debugfs_create_u8("jbd-debug", S_IRUGO,
1887                                               jbd_debugfs_dir,
1888                                               &journal_enable_debug);
1889}
1890
1891static void __exit jbd_remove_debugfs_entry(void)
1892{
1893        debugfs_remove(jbd_debug);
1894        debugfs_remove(jbd_debugfs_dir);
1895}
1896
1897#else
1898
1899static inline void jbd_create_debugfs_entry(void)
1900{
1901}
1902
1903static inline void jbd_remove_debugfs_entry(void)
1904{
1905}
1906
1907#endif
1908
1909struct kmem_cache *jbd_handle_cache;
1910
1911static int __init journal_init_handle_cache(void)
1912{
1913        jbd_handle_cache = kmem_cache_create("journal_handle",
1914                                sizeof(handle_t),
1915                                0,              /* offset */
1916                                SLAB_TEMPORARY, /* flags */
1917                                NULL);          /* ctor */
1918        if (jbd_handle_cache == NULL) {
1919                printk(KERN_EMERG "JBD: failed to create handle cache\n");
1920                return -ENOMEM;
1921        }
1922        return 0;
1923}
1924
1925static void journal_destroy_handle_cache(void)
1926{
1927        if (jbd_handle_cache)
1928                kmem_cache_destroy(jbd_handle_cache);
1929}
1930
1931/*
1932 * Module startup and shutdown
1933 */
1934
1935static int __init journal_init_caches(void)
1936{
1937        int ret;
1938
1939        ret = journal_init_revoke_caches();
1940        if (ret == 0)
1941                ret = journal_init_journal_head_cache();
1942        if (ret == 0)
1943                ret = journal_init_handle_cache();
1944        return ret;
1945}
1946
1947static void journal_destroy_caches(void)
1948{
1949        journal_destroy_revoke_caches();
1950        journal_destroy_journal_head_cache();
1951        journal_destroy_handle_cache();
1952}
1953
1954static int __init journal_init(void)
1955{
1956        int ret;
1957
1958        BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
1959
1960        ret = journal_init_caches();
1961        if (ret != 0)
1962                journal_destroy_caches();
1963        jbd_create_debugfs_entry();
1964        return ret;
1965}
1966
1967static void __exit journal_exit(void)
1968{
1969#ifdef CONFIG_JBD_DEBUG
1970        int n = atomic_read(&nr_journal_heads);
1971        if (n)
1972                printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
1973#endif
1974        jbd_remove_debugfs_entry();
1975        journal_destroy_caches();
1976}
1977
1978MODULE_LICENSE("GPL");
1979module_init(journal_init);
1980module_exit(journal_exit);
1981
1982
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