linux/fs/jbd2/journal.c
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   1/*
   2 * linux/fs/jbd2/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/jbd2.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/seq_file.h>
  39#include <linux/math64.h>
  40#include <linux/hash.h>
  41#include <linux/log2.h>
  42#include <linux/vmalloc.h>
  43#include <linux/backing-dev.h>
  44#include <linux/bitops.h>
  45#include <linux/ratelimit.h>
  46
  47#define CREATE_TRACE_POINTS
  48#include <trace/events/jbd2.h>
  49
  50#include <asm/uaccess.h>
  51#include <asm/page.h>
  52
  53#ifdef CONFIG_JBD2_DEBUG
  54ushort jbd2_journal_enable_debug __read_mostly;
  55EXPORT_SYMBOL(jbd2_journal_enable_debug);
  56
  57module_param_named(jbd2_debug, jbd2_journal_enable_debug, ushort, 0644);
  58MODULE_PARM_DESC(jbd2_debug, "Debugging level for jbd2");
  59#endif
  60
  61EXPORT_SYMBOL(jbd2_journal_extend);
  62EXPORT_SYMBOL(jbd2_journal_stop);
  63EXPORT_SYMBOL(jbd2_journal_lock_updates);
  64EXPORT_SYMBOL(jbd2_journal_unlock_updates);
  65EXPORT_SYMBOL(jbd2_journal_get_write_access);
  66EXPORT_SYMBOL(jbd2_journal_get_create_access);
  67EXPORT_SYMBOL(jbd2_journal_get_undo_access);
  68EXPORT_SYMBOL(jbd2_journal_set_triggers);
  69EXPORT_SYMBOL(jbd2_journal_dirty_metadata);
  70EXPORT_SYMBOL(jbd2_journal_forget);
  71#if 0
  72EXPORT_SYMBOL(journal_sync_buffer);
  73#endif
  74EXPORT_SYMBOL(jbd2_journal_flush);
  75EXPORT_SYMBOL(jbd2_journal_revoke);
  76
  77EXPORT_SYMBOL(jbd2_journal_init_dev);
  78EXPORT_SYMBOL(jbd2_journal_init_inode);
  79EXPORT_SYMBOL(jbd2_journal_check_used_features);
  80EXPORT_SYMBOL(jbd2_journal_check_available_features);
  81EXPORT_SYMBOL(jbd2_journal_set_features);
  82EXPORT_SYMBOL(jbd2_journal_load);
  83EXPORT_SYMBOL(jbd2_journal_destroy);
  84EXPORT_SYMBOL(jbd2_journal_abort);
  85EXPORT_SYMBOL(jbd2_journal_errno);
  86EXPORT_SYMBOL(jbd2_journal_ack_err);
  87EXPORT_SYMBOL(jbd2_journal_clear_err);
  88EXPORT_SYMBOL(jbd2_log_wait_commit);
  89EXPORT_SYMBOL(jbd2_log_start_commit);
  90EXPORT_SYMBOL(jbd2_journal_start_commit);
  91EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
  92EXPORT_SYMBOL(jbd2_journal_wipe);
  93EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
  94EXPORT_SYMBOL(jbd2_journal_invalidatepage);
  95EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
  96EXPORT_SYMBOL(jbd2_journal_force_commit);
  97EXPORT_SYMBOL(jbd2_journal_file_inode);
  98EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
  99EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
 100EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
 101EXPORT_SYMBOL(jbd2_inode_cache);
 102
 103static void __journal_abort_soft (journal_t *journal, int errno);
 104static int jbd2_journal_create_slab(size_t slab_size);
 105
 106#ifdef CONFIG_JBD2_DEBUG
 107void __jbd2_debug(int level, const char *file, const char *func,
 108                  unsigned int line, const char *fmt, ...)
 109{
 110        struct va_format vaf;
 111        va_list args;
 112
 113        if (level > jbd2_journal_enable_debug)
 114                return;
 115        va_start(args, fmt);
 116        vaf.fmt = fmt;
 117        vaf.va = &args;
 118        printk(KERN_DEBUG "%s: (%s, %u): %pV\n", file, func, line, &vaf);
 119        va_end(args);
 120}
 121EXPORT_SYMBOL(__jbd2_debug);
 122#endif
 123
 124/* Checksumming functions */
 125int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
 126{
 127        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 128                return 1;
 129
 130        return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
 131}
 132
 133static __u32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb)
 134{
 135        __u32 csum, old_csum;
 136
 137        old_csum = sb->s_checksum;
 138        sb->s_checksum = 0;
 139        csum = jbd2_chksum(j, ~0, (char *)sb, sizeof(journal_superblock_t));
 140        sb->s_checksum = old_csum;
 141
 142        return cpu_to_be32(csum);
 143}
 144
 145int jbd2_superblock_csum_verify(journal_t *j, journal_superblock_t *sb)
 146{
 147        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 148                return 1;
 149
 150        return sb->s_checksum == jbd2_superblock_csum(j, sb);
 151}
 152
 153void jbd2_superblock_csum_set(journal_t *j, journal_superblock_t *sb)
 154{
 155        if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 156                return;
 157
 158        sb->s_checksum = jbd2_superblock_csum(j, sb);
 159}
 160
 161/*
 162 * Helper function used to manage commit timeouts
 163 */
 164
 165static void commit_timeout(unsigned long __data)
 166{
 167        struct task_struct * p = (struct task_struct *) __data;
 168
 169        wake_up_process(p);
 170}
 171
 172/*
 173 * kjournald2: The main thread function used to manage a logging device
 174 * journal.
 175 *
 176 * This kernel thread is responsible for two things:
 177 *
 178 * 1) COMMIT:  Every so often we need to commit the current state of the
 179 *    filesystem to disk.  The journal thread is responsible for writing
 180 *    all of the metadata buffers to disk.
 181 *
 182 * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
 183 *    of the data in that part of the log has been rewritten elsewhere on
 184 *    the disk.  Flushing these old buffers to reclaim space in the log is
 185 *    known as checkpointing, and this thread is responsible for that job.
 186 */
 187
 188static int kjournald2(void *arg)
 189{
 190        journal_t *journal = arg;
 191        transaction_t *transaction;
 192
 193        /*
 194         * Set up an interval timer which can be used to trigger a commit wakeup
 195         * after the commit interval expires
 196         */
 197        setup_timer(&journal->j_commit_timer, commit_timeout,
 198                        (unsigned long)current);
 199
 200        set_freezable();
 201
 202        /* Record that the journal thread is running */
 203        journal->j_task = current;
 204        wake_up(&journal->j_wait_done_commit);
 205
 206        /*
 207         * And now, wait forever for commit wakeup events.
 208         */
 209        write_lock(&journal->j_state_lock);
 210
 211loop:
 212        if (journal->j_flags & JBD2_UNMOUNT)
 213                goto end_loop;
 214
 215        jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
 216                journal->j_commit_sequence, journal->j_commit_request);
 217
 218        if (journal->j_commit_sequence != journal->j_commit_request) {
 219                jbd_debug(1, "OK, requests differ\n");
 220                write_unlock(&journal->j_state_lock);
 221                del_timer_sync(&journal->j_commit_timer);
 222                jbd2_journal_commit_transaction(journal);
 223                write_lock(&journal->j_state_lock);
 224                goto loop;
 225        }
 226
 227        wake_up(&journal->j_wait_done_commit);
 228        if (freezing(current)) {
 229                /*
 230                 * The simpler the better. Flushing journal isn't a
 231                 * good idea, because that depends on threads that may
 232                 * be already stopped.
 233                 */
 234                jbd_debug(1, "Now suspending kjournald2\n");
 235                write_unlock(&journal->j_state_lock);
 236                try_to_freeze();
 237                write_lock(&journal->j_state_lock);
 238        } else {
 239                /*
 240                 * We assume on resume that commits are already there,
 241                 * so we don't sleep
 242                 */
 243                DEFINE_WAIT(wait);
 244                int should_sleep = 1;
 245
 246                prepare_to_wait(&journal->j_wait_commit, &wait,
 247                                TASK_INTERRUPTIBLE);
 248                if (journal->j_commit_sequence != journal->j_commit_request)
 249                        should_sleep = 0;
 250                transaction = journal->j_running_transaction;
 251                if (transaction && time_after_eq(jiffies,
 252                                                transaction->t_expires))
 253                        should_sleep = 0;
 254                if (journal->j_flags & JBD2_UNMOUNT)
 255                        should_sleep = 0;
 256                if (should_sleep) {
 257                        write_unlock(&journal->j_state_lock);
 258                        schedule();
 259                        write_lock(&journal->j_state_lock);
 260                }
 261                finish_wait(&journal->j_wait_commit, &wait);
 262        }
 263
 264        jbd_debug(1, "kjournald2 wakes\n");
 265
 266        /*
 267         * Were we woken up by a commit wakeup event?
 268         */
 269        transaction = journal->j_running_transaction;
 270        if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
 271                journal->j_commit_request = transaction->t_tid;
 272                jbd_debug(1, "woke because of timeout\n");
 273        }
 274        goto loop;
 275
 276end_loop:
 277        write_unlock(&journal->j_state_lock);
 278        del_timer_sync(&journal->j_commit_timer);
 279        journal->j_task = NULL;
 280        wake_up(&journal->j_wait_done_commit);
 281        jbd_debug(1, "Journal thread exiting.\n");
 282        return 0;
 283}
 284
 285static int jbd2_journal_start_thread(journal_t *journal)
 286{
 287        struct task_struct *t;
 288
 289        t = kthread_run(kjournald2, journal, "jbd2/%s",
 290                        journal->j_devname);
 291        if (IS_ERR(t))
 292                return PTR_ERR(t);
 293
 294        wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
 295        return 0;
 296}
 297
 298static void journal_kill_thread(journal_t *journal)
 299{
 300        write_lock(&journal->j_state_lock);
 301        journal->j_flags |= JBD2_UNMOUNT;
 302
 303        while (journal->j_task) {
 304                wake_up(&journal->j_wait_commit);
 305                write_unlock(&journal->j_state_lock);
 306                wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
 307                write_lock(&journal->j_state_lock);
 308        }
 309        write_unlock(&journal->j_state_lock);
 310}
 311
 312/*
 313 * jbd2_journal_write_metadata_buffer: write a metadata buffer to the journal.
 314 *
 315 * Writes a metadata buffer to a given disk block.  The actual IO is not
 316 * performed but a new buffer_head is constructed which labels the data
 317 * to be written with the correct destination disk block.
 318 *
 319 * Any magic-number escaping which needs to be done will cause a
 320 * copy-out here.  If the buffer happens to start with the
 321 * JBD2_MAGIC_NUMBER, then we can't write it to the log directly: the
 322 * magic number is only written to the log for descripter blocks.  In
 323 * this case, we copy the data and replace the first word with 0, and we
 324 * return a result code which indicates that this buffer needs to be
 325 * marked as an escaped buffer in the corresponding log descriptor
 326 * block.  The missing word can then be restored when the block is read
 327 * during recovery.
 328 *
 329 * If the source buffer has already been modified by a new transaction
 330 * since we took the last commit snapshot, we use the frozen copy of
 331 * that data for IO. If we end up using the existing buffer_head's data
 332 * for the write, then we have to make sure nobody modifies it while the
 333 * IO is in progress. do_get_write_access() handles this.
 334 *
 335 * The function returns a pointer to the buffer_head to be used for IO.
 336 * 
 337 *
 338 * Return value:
 339 *  <0: Error
 340 * >=0: Finished OK
 341 *
 342 * On success:
 343 * Bit 0 set == escape performed on the data
 344 * Bit 1 set == buffer copy-out performed (kfree the data after IO)
 345 */
 346
 347int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 348                                  struct journal_head  *jh_in,
 349                                  struct buffer_head **bh_out,
 350                                  sector_t blocknr)
 351{
 352        int need_copy_out = 0;
 353        int done_copy_out = 0;
 354        int do_escape = 0;
 355        char *mapped_data;
 356        struct buffer_head *new_bh;
 357        struct page *new_page;
 358        unsigned int new_offset;
 359        struct buffer_head *bh_in = jh2bh(jh_in);
 360        journal_t *journal = transaction->t_journal;
 361
 362        /*
 363         * The buffer really shouldn't be locked: only the current committing
 364         * transaction is allowed to write it, so nobody else is allowed
 365         * to do any IO.
 366         *
 367         * akpm: except if we're journalling data, and write() output is
 368         * also part of a shared mapping, and another thread has
 369         * decided to launch a writepage() against this buffer.
 370         */
 371        J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
 372
 373retry_alloc:
 374        new_bh = alloc_buffer_head(GFP_NOFS);
 375        if (!new_bh) {
 376                /*
 377                 * Failure is not an option, but __GFP_NOFAIL is going
 378                 * away; so we retry ourselves here.
 379                 */
 380                congestion_wait(BLK_RW_ASYNC, HZ/50);
 381                goto retry_alloc;
 382        }
 383
 384        /* keep subsequent assertions sane */
 385        atomic_set(&new_bh->b_count, 1);
 386
 387        jbd_lock_bh_state(bh_in);
 388repeat:
 389        /*
 390         * If a new transaction has already done a buffer copy-out, then
 391         * we use that version of the data for the commit.
 392         */
 393        if (jh_in->b_frozen_data) {
 394                done_copy_out = 1;
 395                new_page = virt_to_page(jh_in->b_frozen_data);
 396                new_offset = offset_in_page(jh_in->b_frozen_data);
 397        } else {
 398                new_page = jh2bh(jh_in)->b_page;
 399                new_offset = offset_in_page(jh2bh(jh_in)->b_data);
 400        }
 401
 402        mapped_data = kmap_atomic(new_page);
 403        /*
 404         * Fire data frozen trigger if data already wasn't frozen.  Do this
 405         * before checking for escaping, as the trigger may modify the magic
 406         * offset.  If a copy-out happens afterwards, it will have the correct
 407         * data in the buffer.
 408         */
 409        if (!done_copy_out)
 410                jbd2_buffer_frozen_trigger(jh_in, mapped_data + new_offset,
 411                                           jh_in->b_triggers);
 412
 413        /*
 414         * Check for escaping
 415         */
 416        if (*((__be32 *)(mapped_data + new_offset)) ==
 417                                cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 418                need_copy_out = 1;
 419                do_escape = 1;
 420        }
 421        kunmap_atomic(mapped_data);
 422
 423        /*
 424         * Do we need to do a data copy?
 425         */
 426        if (need_copy_out && !done_copy_out) {
 427                char *tmp;
 428
 429                jbd_unlock_bh_state(bh_in);
 430                tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS);
 431                if (!tmp) {
 432                        brelse(new_bh);
 433                        return -ENOMEM;
 434                }
 435                jbd_lock_bh_state(bh_in);
 436                if (jh_in->b_frozen_data) {
 437                        jbd2_free(tmp, bh_in->b_size);
 438                        goto repeat;
 439                }
 440
 441                jh_in->b_frozen_data = tmp;
 442                mapped_data = kmap_atomic(new_page);
 443                memcpy(tmp, mapped_data + new_offset, bh_in->b_size);
 444                kunmap_atomic(mapped_data);
 445
 446                new_page = virt_to_page(tmp);
 447                new_offset = offset_in_page(tmp);
 448                done_copy_out = 1;
 449
 450                /*
 451                 * This isn't strictly necessary, as we're using frozen
 452                 * data for the escaping, but it keeps consistency with
 453                 * b_frozen_data usage.
 454                 */
 455                jh_in->b_frozen_triggers = jh_in->b_triggers;
 456        }
 457
 458        /*
 459         * Did we need to do an escaping?  Now we've done all the
 460         * copying, we can finally do so.
 461         */
 462        if (do_escape) {
 463                mapped_data = kmap_atomic(new_page);
 464                *((unsigned int *)(mapped_data + new_offset)) = 0;
 465                kunmap_atomic(mapped_data);
 466        }
 467
 468        set_bh_page(new_bh, new_page, new_offset);
 469        new_bh->b_size = bh_in->b_size;
 470        new_bh->b_bdev = journal->j_dev;
 471        new_bh->b_blocknr = blocknr;
 472        new_bh->b_private = bh_in;
 473        set_buffer_mapped(new_bh);
 474        set_buffer_dirty(new_bh);
 475
 476        *bh_out = new_bh;
 477
 478        /*
 479         * The to-be-written buffer needs to get moved to the io queue,
 480         * and the original buffer whose contents we are shadowing or
 481         * copying is moved to the transaction's shadow queue.
 482         */
 483        JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
 484        spin_lock(&journal->j_list_lock);
 485        __jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
 486        spin_unlock(&journal->j_list_lock);
 487        set_buffer_shadow(bh_in);
 488        jbd_unlock_bh_state(bh_in);
 489
 490        return do_escape | (done_copy_out << 1);
 491}
 492
 493/*
 494 * Allocation code for the journal file.  Manage the space left in the
 495 * journal, so that we can begin checkpointing when appropriate.
 496 */
 497
 498/*
 499 * Called with j_state_lock locked for writing.
 500 * Returns true if a transaction commit was started.
 501 */
 502int __jbd2_log_start_commit(journal_t *journal, tid_t target)
 503{
 504        /* Return if the txn has already requested to be committed */
 505        if (journal->j_commit_request == target)
 506                return 0;
 507
 508        /*
 509         * The only transaction we can possibly wait upon is the
 510         * currently running transaction (if it exists).  Otherwise,
 511         * the target tid must be an old one.
 512         */
 513        if (journal->j_running_transaction &&
 514            journal->j_running_transaction->t_tid == target) {
 515                /*
 516                 * We want a new commit: OK, mark the request and wakeup the
 517                 * commit thread.  We do _not_ do the commit ourselves.
 518                 */
 519
 520                journal->j_commit_request = target;
 521                jbd_debug(1, "JBD2: requesting commit %d/%d\n",
 522                          journal->j_commit_request,
 523                          journal->j_commit_sequence);
 524                journal->j_running_transaction->t_requested = jiffies;
 525                wake_up(&journal->j_wait_commit);
 526                return 1;
 527        } else if (!tid_geq(journal->j_commit_request, target))
 528                /* This should never happen, but if it does, preserve
 529                   the evidence before kjournald goes into a loop and
 530                   increments j_commit_sequence beyond all recognition. */
 531                WARN_ONCE(1, "JBD2: bad log_start_commit: %u %u %u %u\n",
 532                          journal->j_commit_request,
 533                          journal->j_commit_sequence,
 534                          target, journal->j_running_transaction ? 
 535                          journal->j_running_transaction->t_tid : 0);
 536        return 0;
 537}
 538
 539int jbd2_log_start_commit(journal_t *journal, tid_t tid)
 540{
 541        int ret;
 542
 543        write_lock(&journal->j_state_lock);
 544        ret = __jbd2_log_start_commit(journal, tid);
 545        write_unlock(&journal->j_state_lock);
 546        return ret;
 547}
 548
 549/*
 550 * Force and wait any uncommitted transactions.  We can only force the running
 551 * transaction if we don't have an active handle, otherwise, we will deadlock.
 552 * Returns: <0 in case of error,
 553 *           0 if nothing to commit,
 554 *           1 if transaction was successfully committed.
 555 */
 556static int __jbd2_journal_force_commit(journal_t *journal)
 557{
 558        transaction_t *transaction = NULL;
 559        tid_t tid;
 560        int need_to_start = 0, ret = 0;
 561
 562        read_lock(&journal->j_state_lock);
 563        if (journal->j_running_transaction && !current->journal_info) {
 564                transaction = journal->j_running_transaction;
 565                if (!tid_geq(journal->j_commit_request, transaction->t_tid))
 566                        need_to_start = 1;
 567        } else if (journal->j_committing_transaction)
 568                transaction = journal->j_committing_transaction;
 569
 570        if (!transaction) {
 571                /* Nothing to commit */
 572                read_unlock(&journal->j_state_lock);
 573                return 0;
 574        }
 575        tid = transaction->t_tid;
 576        read_unlock(&journal->j_state_lock);
 577        if (need_to_start)
 578                jbd2_log_start_commit(journal, tid);
 579        ret = jbd2_log_wait_commit(journal, tid);
 580        if (!ret)
 581                ret = 1;
 582
 583        return ret;
 584}
 585
 586/**
 587 * Force and wait upon a commit if the calling process is not within
 588 * transaction.  This is used for forcing out undo-protected data which contains
 589 * bitmaps, when the fs is running out of space.
 590 *
 591 * @journal: journal to force
 592 * Returns true if progress was made.
 593 */
 594int jbd2_journal_force_commit_nested(journal_t *journal)
 595{
 596        int ret;
 597
 598        ret = __jbd2_journal_force_commit(journal);
 599        return ret > 0;
 600}
 601
 602/**
 603 * int journal_force_commit() - force any uncommitted transactions
 604 * @journal: journal to force
 605 *
 606 * Caller want unconditional commit. We can only force the running transaction
 607 * if we don't have an active handle, otherwise, we will deadlock.
 608 */
 609int jbd2_journal_force_commit(journal_t *journal)
 610{
 611        int ret;
 612
 613        J_ASSERT(!current->journal_info);
 614        ret = __jbd2_journal_force_commit(journal);
 615        if (ret > 0)
 616                ret = 0;
 617        return ret;
 618}
 619
 620/*
 621 * Start a commit of the current running transaction (if any).  Returns true
 622 * if a transaction is going to be committed (or is currently already
 623 * committing), and fills its tid in at *ptid
 624 */
 625int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
 626{
 627        int ret = 0;
 628
 629        write_lock(&journal->j_state_lock);
 630        if (journal->j_running_transaction) {
 631                tid_t tid = journal->j_running_transaction->t_tid;
 632
 633                __jbd2_log_start_commit(journal, tid);
 634                /* There's a running transaction and we've just made sure
 635                 * it's commit has been scheduled. */
 636                if (ptid)
 637                        *ptid = tid;
 638                ret = 1;
 639        } else if (journal->j_committing_transaction) {
 640                /*
 641                 * If commit has been started, then we have to wait for
 642                 * completion of that transaction.
 643                 */
 644                if (ptid)
 645                        *ptid = journal->j_committing_transaction->t_tid;
 646                ret = 1;
 647        }
 648        write_unlock(&journal->j_state_lock);
 649        return ret;
 650}
 651
 652/*
 653 * Return 1 if a given transaction has not yet sent barrier request
 654 * connected with a transaction commit. If 0 is returned, transaction
 655 * may or may not have sent the barrier. Used to avoid sending barrier
 656 * twice in common cases.
 657 */
 658int jbd2_trans_will_send_data_barrier(journal_t *journal, tid_t tid)
 659{
 660        int ret = 0;
 661        transaction_t *commit_trans;
 662
 663        if (!(journal->j_flags & JBD2_BARRIER))
 664                return 0;
 665        read_lock(&journal->j_state_lock);
 666        /* Transaction already committed? */
 667        if (tid_geq(journal->j_commit_sequence, tid))
 668                goto out;
 669        commit_trans = journal->j_committing_transaction;
 670        if (!commit_trans || commit_trans->t_tid != tid) {
 671                ret = 1;
 672                goto out;
 673        }
 674        /*
 675         * Transaction is being committed and we already proceeded to
 676         * submitting a flush to fs partition?
 677         */
 678        if (journal->j_fs_dev != journal->j_dev) {
 679                if (!commit_trans->t_need_data_flush ||
 680                    commit_trans->t_state >= T_COMMIT_DFLUSH)
 681                        goto out;
 682        } else {
 683                if (commit_trans->t_state >= T_COMMIT_JFLUSH)
 684                        goto out;
 685        }
 686        ret = 1;
 687out:
 688        read_unlock(&journal->j_state_lock);
 689        return ret;
 690}
 691EXPORT_SYMBOL(jbd2_trans_will_send_data_barrier);
 692
 693/*
 694 * Wait for a specified commit to complete.
 695 * The caller may not hold the journal lock.
 696 */
 697int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
 698{
 699        int err = 0;
 700
 701        read_lock(&journal->j_state_lock);
 702#ifdef CONFIG_JBD2_DEBUG
 703        if (!tid_geq(journal->j_commit_request, tid)) {
 704                printk(KERN_EMERG
 705                       "%s: error: j_commit_request=%d, tid=%d\n",
 706                       __func__, journal->j_commit_request, tid);
 707        }
 708#endif
 709        while (tid_gt(tid, journal->j_commit_sequence)) {
 710                jbd_debug(1, "JBD2: want %d, j_commit_sequence=%d\n",
 711                                  tid, journal->j_commit_sequence);
 712                wake_up(&journal->j_wait_commit);
 713                read_unlock(&journal->j_state_lock);
 714                wait_event(journal->j_wait_done_commit,
 715                                !tid_gt(tid, journal->j_commit_sequence));
 716                read_lock(&journal->j_state_lock);
 717        }
 718        read_unlock(&journal->j_state_lock);
 719
 720        if (unlikely(is_journal_aborted(journal))) {
 721                printk(KERN_EMERG "journal commit I/O error\n");
 722                err = -EIO;
 723        }
 724        return err;
 725}
 726
 727/*
 728 * When this function returns the transaction corresponding to tid
 729 * will be completed.  If the transaction has currently running, start
 730 * committing that transaction before waiting for it to complete.  If
 731 * the transaction id is stale, it is by definition already completed,
 732 * so just return SUCCESS.
 733 */
 734int jbd2_complete_transaction(journal_t *journal, tid_t tid)
 735{
 736        int     need_to_wait = 1;
 737
 738        read_lock(&journal->j_state_lock);
 739        if (journal->j_running_transaction &&
 740            journal->j_running_transaction->t_tid == tid) {
 741                if (journal->j_commit_request != tid) {
 742                        /* transaction not yet started, so request it */
 743                        read_unlock(&journal->j_state_lock);
 744                        jbd2_log_start_commit(journal, tid);
 745                        goto wait_commit;
 746                }
 747        } else if (!(journal->j_committing_transaction &&
 748                     journal->j_committing_transaction->t_tid == tid))
 749                need_to_wait = 0;
 750        read_unlock(&journal->j_state_lock);
 751        if (!need_to_wait)
 752                return 0;
 753wait_commit:
 754        return jbd2_log_wait_commit(journal, tid);
 755}
 756EXPORT_SYMBOL(jbd2_complete_transaction);
 757
 758/*
 759 * Log buffer allocation routines:
 760 */
 761
 762int jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
 763{
 764        unsigned long blocknr;
 765
 766        write_lock(&journal->j_state_lock);
 767        J_ASSERT(journal->j_free > 1);
 768
 769        blocknr = journal->j_head;
 770        journal->j_head++;
 771        journal->j_free--;
 772        if (journal->j_head == journal->j_last)
 773                journal->j_head = journal->j_first;
 774        write_unlock(&journal->j_state_lock);
 775        return jbd2_journal_bmap(journal, blocknr, retp);
 776}
 777
 778/*
 779 * Conversion of logical to physical block numbers for the journal
 780 *
 781 * On external journals the journal blocks are identity-mapped, so
 782 * this is a no-op.  If needed, we can use j_blk_offset - everything is
 783 * ready.
 784 */
 785int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
 786                 unsigned long long *retp)
 787{
 788        int err = 0;
 789        unsigned long long ret;
 790
 791        if (journal->j_inode) {
 792                ret = bmap(journal->j_inode, blocknr);
 793                if (ret)
 794                        *retp = ret;
 795                else {
 796                        printk(KERN_ALERT "%s: journal block not found "
 797                                        "at offset %lu on %s\n",
 798                               __func__, blocknr, journal->j_devname);
 799                        err = -EIO;
 800                        __journal_abort_soft(journal, err);
 801                }
 802        } else {
 803                *retp = blocknr; /* +journal->j_blk_offset */
 804        }
 805        return err;
 806}
 807
 808/*
 809 * We play buffer_head aliasing tricks to write data/metadata blocks to
 810 * the journal without copying their contents, but for journal
 811 * descriptor blocks we do need to generate bona fide buffers.
 812 *
 813 * After the caller of jbd2_journal_get_descriptor_buffer() has finished modifying
 814 * the buffer's contents they really should run flush_dcache_page(bh->b_page).
 815 * But we don't bother doing that, so there will be coherency problems with
 816 * mmaps of blockdevs which hold live JBD-controlled filesystems.
 817 */
 818struct buffer_head *jbd2_journal_get_descriptor_buffer(journal_t *journal)
 819{
 820        struct buffer_head *bh;
 821        unsigned long long blocknr;
 822        int err;
 823
 824        err = jbd2_journal_next_log_block(journal, &blocknr);
 825
 826        if (err)
 827                return NULL;
 828
 829        bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 830        if (!bh)
 831                return NULL;
 832        lock_buffer(bh);
 833        memset(bh->b_data, 0, journal->j_blocksize);
 834        set_buffer_uptodate(bh);
 835        unlock_buffer(bh);
 836        BUFFER_TRACE(bh, "return this buffer");
 837        return bh;
 838}
 839
 840/*
 841 * Return tid of the oldest transaction in the journal and block in the journal
 842 * where the transaction starts.
 843 *
 844 * If the journal is now empty, return which will be the next transaction ID
 845 * we will write and where will that transaction start.
 846 *
 847 * The return value is 0 if journal tail cannot be pushed any further, 1 if
 848 * it can.
 849 */
 850int jbd2_journal_get_log_tail(journal_t *journal, tid_t *tid,
 851                              unsigned long *block)
 852{
 853        transaction_t *transaction;
 854        int ret;
 855
 856        read_lock(&journal->j_state_lock);
 857        spin_lock(&journal->j_list_lock);
 858        transaction = journal->j_checkpoint_transactions;
 859        if (transaction) {
 860                *tid = transaction->t_tid;
 861                *block = transaction->t_log_start;
 862        } else if ((transaction = journal->j_committing_transaction) != NULL) {
 863                *tid = transaction->t_tid;
 864                *block = transaction->t_log_start;
 865        } else if ((transaction = journal->j_running_transaction) != NULL) {
 866                *tid = transaction->t_tid;
 867                *block = journal->j_head;
 868        } else {
 869                *tid = journal->j_transaction_sequence;
 870                *block = journal->j_head;
 871        }
 872        ret = tid_gt(*tid, journal->j_tail_sequence);
 873        spin_unlock(&journal->j_list_lock);
 874        read_unlock(&journal->j_state_lock);
 875
 876        return ret;
 877}
 878
 879/*
 880 * Update information in journal structure and in on disk journal superblock
 881 * about log tail. This function does not check whether information passed in
 882 * really pushes log tail further. It's responsibility of the caller to make
 883 * sure provided log tail information is valid (e.g. by holding
 884 * j_checkpoint_mutex all the time between computing log tail and calling this
 885 * function as is the case with jbd2_cleanup_journal_tail()).
 886 *
 887 * Requires j_checkpoint_mutex
 888 */
 889void __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
 890{
 891        unsigned long freed;
 892
 893        BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
 894
 895        /*
 896         * We cannot afford for write to remain in drive's caches since as
 897         * soon as we update j_tail, next transaction can start reusing journal
 898         * space and if we lose sb update during power failure we'd replay
 899         * old transaction with possibly newly overwritten data.
 900         */
 901        jbd2_journal_update_sb_log_tail(journal, tid, block, WRITE_FUA);
 902        write_lock(&journal->j_state_lock);
 903        freed = block - journal->j_tail;
 904        if (block < journal->j_tail)
 905                freed += journal->j_last - journal->j_first;
 906
 907        trace_jbd2_update_log_tail(journal, tid, block, freed);
 908        jbd_debug(1,
 909                  "Cleaning journal tail from %d to %d (offset %lu), "
 910                  "freeing %lu\n",
 911                  journal->j_tail_sequence, tid, block, freed);
 912
 913        journal->j_free += freed;
 914        journal->j_tail_sequence = tid;
 915        journal->j_tail = block;
 916        write_unlock(&journal->j_state_lock);
 917}
 918
 919/*
 920 * This is a variaon of __jbd2_update_log_tail which checks for validity of
 921 * provided log tail and locks j_checkpoint_mutex. So it is safe against races
 922 * with other threads updating log tail.
 923 */
 924void jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
 925{
 926        mutex_lock(&journal->j_checkpoint_mutex);
 927        if (tid_gt(tid, journal->j_tail_sequence))
 928                __jbd2_update_log_tail(journal, tid, block);
 929        mutex_unlock(&journal->j_checkpoint_mutex);
 930}
 931
 932struct jbd2_stats_proc_session {
 933        journal_t *journal;
 934        struct transaction_stats_s *stats;
 935        int start;
 936        int max;
 937};
 938
 939static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos)
 940{
 941        return *pos ? NULL : SEQ_START_TOKEN;
 942}
 943
 944static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
 945{
 946        return NULL;
 947}
 948
 949static int jbd2_seq_info_show(struct seq_file *seq, void *v)
 950{
 951        struct jbd2_stats_proc_session *s = seq->private;
 952
 953        if (v != SEQ_START_TOKEN)
 954                return 0;
 955        seq_printf(seq, "%lu transactions (%lu requested), "
 956                   "each up to %u blocks\n",
 957                   s->stats->ts_tid, s->stats->ts_requested,
 958                   s->journal->j_max_transaction_buffers);
 959        if (s->stats->ts_tid == 0)
 960                return 0;
 961        seq_printf(seq, "average: \n  %ums waiting for transaction\n",
 962            jiffies_to_msecs(s->stats->run.rs_wait / s->stats->ts_tid));
 963        seq_printf(seq, "  %ums request delay\n",
 964            (s->stats->ts_requested == 0) ? 0 :
 965            jiffies_to_msecs(s->stats->run.rs_request_delay /
 966                             s->stats->ts_requested));
 967        seq_printf(seq, "  %ums running transaction\n",
 968            jiffies_to_msecs(s->stats->run.rs_running / s->stats->ts_tid));
 969        seq_printf(seq, "  %ums transaction was being locked\n",
 970            jiffies_to_msecs(s->stats->run.rs_locked / s->stats->ts_tid));
 971        seq_printf(seq, "  %ums flushing data (in ordered mode)\n",
 972            jiffies_to_msecs(s->stats->run.rs_flushing / s->stats->ts_tid));
 973        seq_printf(seq, "  %ums logging transaction\n",
 974            jiffies_to_msecs(s->stats->run.rs_logging / s->stats->ts_tid));
 975        seq_printf(seq, "  %lluus average transaction commit time\n",
 976                   div_u64(s->journal->j_average_commit_time, 1000));
 977        seq_printf(seq, "  %lu handles per transaction\n",
 978            s->stats->run.rs_handle_count / s->stats->ts_tid);
 979        seq_printf(seq, "  %lu blocks per transaction\n",
 980            s->stats->run.rs_blocks / s->stats->ts_tid);
 981        seq_printf(seq, "  %lu logged blocks per transaction\n",
 982            s->stats->run.rs_blocks_logged / s->stats->ts_tid);
 983        return 0;
 984}
 985
 986static void jbd2_seq_info_stop(struct seq_file *seq, void *v)
 987{
 988}
 989
 990static const struct seq_operations jbd2_seq_info_ops = {
 991        .start  = jbd2_seq_info_start,
 992        .next   = jbd2_seq_info_next,
 993        .stop   = jbd2_seq_info_stop,
 994        .show   = jbd2_seq_info_show,
 995};
 996
 997static int jbd2_seq_info_open(struct inode *inode, struct file *file)
 998{
 999        journal_t *journal = PDE_DATA(inode);
1000        struct jbd2_stats_proc_session *s;
1001        int rc, size;
1002
1003        s = kmalloc(sizeof(*s), GFP_KERNEL);
1004        if (s == NULL)
1005                return -ENOMEM;
1006        size = sizeof(struct transaction_stats_s);
1007        s->stats = kmalloc(size, GFP_KERNEL);
1008        if (s->stats == NULL) {
1009                kfree(s);
1010                return -ENOMEM;
1011        }
1012        spin_lock(&journal->j_history_lock);
1013        memcpy(s->stats, &journal->j_stats, size);
1014        s->journal = journal;
1015        spin_unlock(&journal->j_history_lock);
1016
1017        rc = seq_open(file, &jbd2_seq_info_ops);
1018        if (rc == 0) {
1019                struct seq_file *m = file->private_data;
1020                m->private = s;
1021        } else {
1022                kfree(s->stats);
1023                kfree(s);
1024        }
1025        return rc;
1026
1027}
1028
1029static int jbd2_seq_info_release(struct inode *inode, struct file *file)
1030{
1031        struct seq_file *seq = file->private_data;
1032        struct jbd2_stats_proc_session *s = seq->private;
1033        kfree(s->stats);
1034        kfree(s);
1035        return seq_release(inode, file);
1036}
1037
1038static const struct file_operations jbd2_seq_info_fops = {
1039        .owner          = THIS_MODULE,
1040        .open           = jbd2_seq_info_open,
1041        .read           = seq_read,
1042        .llseek         = seq_lseek,
1043        .release        = jbd2_seq_info_release,
1044};
1045
1046static struct proc_dir_entry *proc_jbd2_stats;
1047
1048static void jbd2_stats_proc_init(journal_t *journal)
1049{
1050        journal->j_proc_entry = proc_mkdir(journal->j_devname, proc_jbd2_stats);
1051        if (journal->j_proc_entry) {
1052                proc_create_data("info", S_IRUGO, journal->j_proc_entry,
1053                                 &jbd2_seq_info_fops, journal);
1054        }
1055}
1056
1057static void jbd2_stats_proc_exit(journal_t *journal)
1058{
1059        remove_proc_entry("info", journal->j_proc_entry);
1060        remove_proc_entry(journal->j_devname, proc_jbd2_stats);
1061}
1062
1063/*
1064 * Management for journal control blocks: functions to create and
1065 * destroy journal_t structures, and to initialise and read existing
1066 * journal blocks from disk.  */
1067
1068/* First: create and setup a journal_t object in memory.  We initialise
1069 * very few fields yet: that has to wait until we have created the
1070 * journal structures from from scratch, or loaded them from disk. */
1071
1072static journal_t * journal_init_common (void)
1073{
1074        journal_t *journal;
1075        int err;
1076
1077        journal = kzalloc(sizeof(*journal), GFP_KERNEL);
1078        if (!journal)
1079                return NULL;
1080
1081        init_waitqueue_head(&journal->j_wait_transaction_locked);
1082        init_waitqueue_head(&journal->j_wait_done_commit);
1083        init_waitqueue_head(&journal->j_wait_commit);
1084        init_waitqueue_head(&journal->j_wait_updates);
1085        init_waitqueue_head(&journal->j_wait_reserved);
1086        mutex_init(&journal->j_barrier);
1087        mutex_init(&journal->j_checkpoint_mutex);
1088        spin_lock_init(&journal->j_revoke_lock);
1089        spin_lock_init(&journal->j_list_lock);
1090        rwlock_init(&journal->j_state_lock);
1091
1092        journal->j_commit_interval = (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE);
1093        journal->j_min_batch_time = 0;
1094        journal->j_max_batch_time = 15000; /* 15ms */
1095        atomic_set(&journal->j_reserved_credits, 0);
1096
1097        /* The journal is marked for error until we succeed with recovery! */
1098        journal->j_flags = JBD2_ABORT;
1099
1100        /* Set up a default-sized revoke table for the new mount. */
1101        err = jbd2_journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
1102        if (err) {
1103                kfree(journal);
1104                return NULL;
1105        }
1106
1107        spin_lock_init(&journal->j_history_lock);
1108
1109        return journal;
1110}
1111
1112/* jbd2_journal_init_dev and jbd2_journal_init_inode:
1113 *
1114 * Create a journal structure assigned some fixed set of disk blocks to
1115 * the journal.  We don't actually touch those disk blocks yet, but we
1116 * need to set up all of the mapping information to tell the journaling
1117 * system where the journal blocks are.
1118 *
1119 */
1120
1121/**
1122 *  journal_t * jbd2_journal_init_dev() - creates and initialises a journal structure
1123 *  @bdev: Block device on which to create the journal
1124 *  @fs_dev: Device which hold journalled filesystem for this journal.
1125 *  @start: Block nr Start of journal.
1126 *  @len:  Length of the journal in blocks.
1127 *  @blocksize: blocksize of journalling device
1128 *
1129 *  Returns: a newly created journal_t *
1130 *
1131 *  jbd2_journal_init_dev creates a journal which maps a fixed contiguous
1132 *  range of blocks on an arbitrary block device.
1133 *
1134 */
1135journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1136                        struct block_device *fs_dev,
1137                        unsigned long long start, int len, int blocksize)
1138{
1139        journal_t *journal = journal_init_common();
1140        struct buffer_head *bh;
1141        char *p;
1142        int n;
1143
1144        if (!journal)
1145                return NULL;
1146
1147        /* journal descriptor can store up to n blocks -bzzz */
1148        journal->j_blocksize = blocksize;
1149        journal->j_dev = bdev;
1150        journal->j_fs_dev = fs_dev;
1151        journal->j_blk_offset = start;
1152        journal->j_maxlen = len;
1153        bdevname(journal->j_dev, journal->j_devname);
1154        p = journal->j_devname;
1155        while ((p = strchr(p, '/')))
1156                *p = '!';
1157        jbd2_stats_proc_init(journal);
1158        n = journal->j_blocksize / sizeof(journal_block_tag_t);
1159        journal->j_wbufsize = n;
1160        journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
1161        if (!journal->j_wbuf) {
1162                printk(KERN_ERR "%s: Can't allocate bhs for commit thread\n",
1163                        __func__);
1164                goto out_err;
1165        }
1166
1167        bh = __getblk(journal->j_dev, start, journal->j_blocksize);
1168        if (!bh) {
1169                printk(KERN_ERR
1170                       "%s: Cannot get buffer for journal superblock\n",
1171                       __func__);
1172                goto out_err;
1173        }
1174        journal->j_sb_buffer = bh;
1175        journal->j_superblock = (journal_superblock_t *)bh->b_data;
1176
1177        return journal;
1178out_err:
1179        kfree(journal->j_wbuf);
1180        jbd2_stats_proc_exit(journal);
1181        kfree(journal);
1182        return NULL;
1183}
1184
1185/**
1186 *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
1187 *  @inode: An inode to create the journal in
1188 *
1189 * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
1190 * the journal.  The inode must exist already, must support bmap() and
1191 * must have all data blocks preallocated.
1192 */
1193journal_t * jbd2_journal_init_inode (struct inode *inode)
1194{
1195        struct buffer_head *bh;
1196        journal_t *journal = journal_init_common();
1197        char *p;
1198        int err;
1199        int n;
1200        unsigned long long blocknr;
1201
1202        if (!journal)
1203                return NULL;
1204
1205        journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
1206        journal->j_inode = inode;
1207        bdevname(journal->j_dev, journal->j_devname);
1208        p = journal->j_devname;
1209        while ((p = strchr(p, '/')))
1210                *p = '!';
1211        p = journal->j_devname + strlen(journal->j_devname);
1212        sprintf(p, "-%lu", journal->j_inode->i_ino);
1213        jbd_debug(1,
1214                  "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
1215                  journal, inode->i_sb->s_id, inode->i_ino,
1216                  (long long) inode->i_size,
1217                  inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
1218
1219        journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
1220        journal->j_blocksize = inode->i_sb->s_blocksize;
1221        jbd2_stats_proc_init(journal);
1222
1223        /* journal descriptor can store up to n blocks -bzzz */
1224        n = journal->j_blocksize / sizeof(journal_block_tag_t);
1225        journal->j_wbufsize = n;
1226        journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
1227        if (!journal->j_wbuf) {
1228                printk(KERN_ERR "%s: Can't allocate bhs for commit thread\n",
1229                        __func__);
1230                goto out_err;
1231        }
1232
1233        err = jbd2_journal_bmap(journal, 0, &blocknr);
1234        /* If that failed, give up */
1235        if (err) {
1236                printk(KERN_ERR "%s: Cannot locate journal superblock\n",
1237                       __func__);
1238                goto out_err;
1239        }
1240
1241        bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
1242        if (!bh) {
1243                printk(KERN_ERR
1244                       "%s: Cannot get buffer for journal superblock\n",
1245                       __func__);
1246                goto out_err;
1247        }
1248        journal->j_sb_buffer = bh;
1249        journal->j_superblock = (journal_superblock_t *)bh->b_data;
1250
1251        return journal;
1252out_err:
1253        kfree(journal->j_wbuf);
1254        jbd2_stats_proc_exit(journal);
1255        kfree(journal);
1256        return NULL;
1257}
1258
1259/*
1260 * If the journal init or create aborts, we need to mark the journal
1261 * superblock as being NULL to prevent the journal destroy from writing
1262 * back a bogus superblock.
1263 */
1264static void journal_fail_superblock (journal_t *journal)
1265{
1266        struct buffer_head *bh = journal->j_sb_buffer;
1267        brelse(bh);
1268        journal->j_sb_buffer = NULL;
1269}
1270
1271/*
1272 * Given a journal_t structure, initialise the various fields for
1273 * startup of a new journaling session.  We use this both when creating
1274 * a journal, and after recovering an old journal to reset it for
1275 * subsequent use.
1276 */
1277
1278static int journal_reset(journal_t *journal)
1279{
1280        journal_superblock_t *sb = journal->j_superblock;
1281        unsigned long long first, last;
1282
1283        first = be32_to_cpu(sb->s_first);
1284        last = be32_to_cpu(sb->s_maxlen);
1285        if (first + JBD2_MIN_JOURNAL_BLOCKS > last + 1) {
1286                printk(KERN_ERR "JBD2: Journal too short (blocks %llu-%llu).\n",
1287                       first, last);
1288                journal_fail_superblock(journal);
1289                return -EINVAL;
1290        }
1291
1292        journal->j_first = first;
1293        journal->j_last = last;
1294
1295        journal->j_head = first;
1296        journal->j_tail = first;
1297        journal->j_free = last - first;
1298
1299        journal->j_tail_sequence = journal->j_transaction_sequence;
1300        journal->j_commit_sequence = journal->j_transaction_sequence - 1;
1301        journal->j_commit_request = journal->j_commit_sequence;
1302
1303        journal->j_max_transaction_buffers = journal->j_maxlen / 4;
1304
1305        /*
1306         * As a special case, if the on-disk copy is already marked as needing
1307         * no recovery (s_start == 0), then we can safely defer the superblock
1308         * update until the next commit by setting JBD2_FLUSHED.  This avoids
1309         * attempting a write to a potential-readonly device.
1310         */
1311        if (sb->s_start == 0) {
1312                jbd_debug(1, "JBD2: Skipping superblock update on recovered sb "
1313                        "(start %ld, seq %d, errno %d)\n",
1314                        journal->j_tail, journal->j_tail_sequence,
1315                        journal->j_errno);
1316                journal->j_flags |= JBD2_FLUSHED;
1317        } else {
1318                /* Lock here to make assertions happy... */
1319                mutex_lock(&journal->j_checkpoint_mutex);
1320                /*
1321                 * Update log tail information. We use WRITE_FUA since new
1322                 * transaction will start reusing journal space and so we
1323                 * must make sure information about current log tail is on
1324                 * disk before that.
1325                 */
1326                jbd2_journal_update_sb_log_tail(journal,
1327                                                journal->j_tail_sequence,
1328                                                journal->j_tail,
1329                                                WRITE_FUA);
1330                mutex_unlock(&journal->j_checkpoint_mutex);
1331        }
1332        return jbd2_journal_start_thread(journal);
1333}
1334
1335static void jbd2_write_superblock(journal_t *journal, int write_op)
1336{
1337        struct buffer_head *bh = journal->j_sb_buffer;
1338        journal_superblock_t *sb = journal->j_superblock;
1339        int ret;
1340
1341        trace_jbd2_write_superblock(journal, write_op);
1342        if (!(journal->j_flags & JBD2_BARRIER))
1343                write_op &= ~(REQ_FUA | REQ_FLUSH);
1344        lock_buffer(bh);
1345        if (buffer_write_io_error(bh)) {
1346                /*
1347                 * Oh, dear.  A previous attempt to write the journal
1348                 * superblock failed.  This could happen because the
1349                 * USB device was yanked out.  Or it could happen to
1350                 * be a transient write error and maybe the block will
1351                 * be remapped.  Nothing we can do but to retry the
1352                 * write and hope for the best.
1353                 */
1354                printk(KERN_ERR "JBD2: previous I/O error detected "
1355                       "for journal superblock update for %s.\n",
1356                       journal->j_devname);
1357                clear_buffer_write_io_error(bh);
1358                set_buffer_uptodate(bh);
1359        }
1360        jbd2_superblock_csum_set(journal, sb);
1361        get_bh(bh);
1362        bh->b_end_io = end_buffer_write_sync;
1363        ret = submit_bh(write_op, bh);
1364        wait_on_buffer(bh);
1365        if (buffer_write_io_error(bh)) {
1366                clear_buffer_write_io_error(bh);
1367                set_buffer_uptodate(bh);
1368                ret = -EIO;
1369        }
1370        if (ret) {
1371                printk(KERN_ERR "JBD2: Error %d detected when updating "
1372                       "journal superblock for %s.\n", ret,
1373                       journal->j_devname);
1374        }
1375}
1376
1377/**
1378 * jbd2_journal_update_sb_log_tail() - Update log tail in journal sb on disk.
1379 * @journal: The journal to update.
1380 * @tail_tid: TID of the new transaction at the tail of the log
1381 * @tail_block: The first block of the transaction at the tail of the log
1382 * @write_op: With which operation should we write the journal sb
1383 *
1384 * Update a journal's superblock information about log tail and write it to
1385 * disk, waiting for the IO to complete.
1386 */
1387void jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
1388                                     unsigned long tail_block, int write_op)
1389{
1390        journal_superblock_t *sb = journal->j_superblock;
1391
1392        BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1393        jbd_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n",
1394                  tail_block, tail_tid);
1395
1396        sb->s_sequence = cpu_to_be32(tail_tid);
1397        sb->s_start    = cpu_to_be32(tail_block);
1398
1399        jbd2_write_superblock(journal, write_op);
1400
1401        /* Log is no longer empty */
1402        write_lock(&journal->j_state_lock);
1403        WARN_ON(!sb->s_sequence);
1404        journal->j_flags &= ~JBD2_FLUSHED;
1405        write_unlock(&journal->j_state_lock);
1406}
1407
1408/**
1409 * jbd2_mark_journal_empty() - Mark on disk journal as empty.
1410 * @journal: The journal to update.
1411 *
1412 * Update a journal's dynamic superblock fields to show that journal is empty.
1413 * Write updated superblock to disk waiting for IO to complete.
1414 */
1415static void jbd2_mark_journal_empty(journal_t *journal)
1416{
1417        journal_superblock_t *sb = journal->j_superblock;
1418
1419        BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
1420        read_lock(&journal->j_state_lock);
1421        /* Is it already empty? */
1422        if (sb->s_start == 0) {
1423                read_unlock(&journal->j_state_lock);
1424                return;
1425        }
1426        jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n",
1427                  journal->j_tail_sequence);
1428
1429        sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
1430        sb->s_start    = cpu_to_be32(0);
1431        read_unlock(&journal->j_state_lock);
1432
1433        jbd2_write_superblock(journal, WRITE_FUA);
1434
1435        /* Log is no longer empty */
1436        write_lock(&journal->j_state_lock);
1437        journal->j_flags |= JBD2_FLUSHED;
1438        write_unlock(&journal->j_state_lock);
1439}
1440
1441
1442/**
1443 * jbd2_journal_update_sb_errno() - Update error in the journal.
1444 * @journal: The journal to update.
1445 *
1446 * Update a journal's errno.  Write updated superblock to disk waiting for IO
1447 * to complete.
1448 */
1449void jbd2_journal_update_sb_errno(journal_t *journal)
1450{
1451        journal_superblock_t *sb = journal->j_superblock;
1452
1453        read_lock(&journal->j_state_lock);
1454        jbd_debug(1, "JBD2: updating superblock error (errno %d)\n",
1455                  journal->j_errno);
1456        sb->s_errno    = cpu_to_be32(journal->j_errno);
1457        read_unlock(&journal->j_state_lock);
1458
1459        jbd2_write_superblock(journal, WRITE_SYNC);
1460}
1461EXPORT_SYMBOL(jbd2_journal_update_sb_errno);
1462
1463/*
1464 * Read the superblock for a given journal, performing initial
1465 * validation of the format.
1466 */
1467static int journal_get_superblock(journal_t *journal)
1468{
1469        struct buffer_head *bh;
1470        journal_superblock_t *sb;
1471        int err = -EIO;
1472
1473        bh = journal->j_sb_buffer;
1474
1475        J_ASSERT(bh != NULL);
1476        if (!buffer_uptodate(bh)) {
1477                ll_rw_block(READ, 1, &bh);
1478                wait_on_buffer(bh);
1479                if (!buffer_uptodate(bh)) {
1480                        printk(KERN_ERR
1481                                "JBD2: IO error reading journal superblock\n");
1482                        goto out;
1483                }
1484        }
1485
1486        if (buffer_verified(bh))
1487                return 0;
1488
1489        sb = journal->j_superblock;
1490
1491        err = -EINVAL;
1492
1493        if (sb->s_header.h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER) ||
1494            sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1495                printk(KERN_WARNING "JBD2: no valid journal superblock found\n");
1496                goto out;
1497        }
1498
1499        switch(be32_to_cpu(sb->s_header.h_blocktype)) {
1500        case JBD2_SUPERBLOCK_V1:
1501                journal->j_format_version = 1;
1502                break;
1503        case JBD2_SUPERBLOCK_V2:
1504                journal->j_format_version = 2;
1505                break;
1506        default:
1507                printk(KERN_WARNING "JBD2: unrecognised superblock format ID\n");
1508                goto out;
1509        }
1510
1511        if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
1512                journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
1513        else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
1514                printk(KERN_WARNING "JBD2: journal file too short\n");
1515                goto out;
1516        }
1517
1518        if (be32_to_cpu(sb->s_first) == 0 ||
1519            be32_to_cpu(sb->s_first) >= journal->j_maxlen) {
1520                printk(KERN_WARNING
1521                        "JBD2: Invalid start block of journal: %u\n",
1522                        be32_to_cpu(sb->s_first));
1523                goto out;
1524        }
1525
1526        if (JBD2_HAS_COMPAT_FEATURE(journal, JBD2_FEATURE_COMPAT_CHECKSUM) &&
1527            JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
1528                /* Can't have checksum v1 and v2 on at the same time! */
1529                printk(KERN_ERR "JBD: Can't enable checksumming v1 and v2 "
1530                       "at the same time!\n");
1531                goto out;
1532        }
1533
1534        if (!jbd2_verify_csum_type(journal, sb)) {
1535                printk(KERN_ERR "JBD: Unknown checksum type\n");
1536                goto out;
1537        }
1538
1539        /* Load the checksum driver */
1540        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
1541                journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
1542                if (IS_ERR(journal->j_chksum_driver)) {
1543                        printk(KERN_ERR "JBD: Cannot load crc32c driver.\n");
1544                        err = PTR_ERR(journal->j_chksum_driver);
1545                        journal->j_chksum_driver = NULL;
1546                        goto out;
1547                }
1548        }
1549
1550        /* Check superblock checksum */
1551        if (!jbd2_superblock_csum_verify(journal, sb)) {
1552                printk(KERN_ERR "JBD: journal checksum error\n");
1553                goto out;
1554        }
1555
1556        /* Precompute checksum seed for all metadata */
1557        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
1558                journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid,
1559                                                   sizeof(sb->s_uuid));
1560
1561        set_buffer_verified(bh);
1562
1563        return 0;
1564
1565out:
1566        journal_fail_superblock(journal);
1567        return err;
1568}
1569
1570/*
1571 * Load the on-disk journal superblock and read the key fields into the
1572 * journal_t.
1573 */
1574
1575static int load_superblock(journal_t *journal)
1576{
1577        int err;
1578        journal_superblock_t *sb;
1579
1580        err = journal_get_superblock(journal);
1581        if (err)
1582                return err;
1583
1584        sb = journal->j_superblock;
1585
1586        journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1587        journal->j_tail = be32_to_cpu(sb->s_start);
1588        journal->j_first = be32_to_cpu(sb->s_first);
1589        journal->j_last = be32_to_cpu(sb->s_maxlen);
1590        journal->j_errno = be32_to_cpu(sb->s_errno);
1591
1592        return 0;
1593}
1594
1595
1596/**
1597 * int jbd2_journal_load() - Read journal from disk.
1598 * @journal: Journal to act on.
1599 *
1600 * Given a journal_t structure which tells us which disk blocks contain
1601 * a journal, read the journal from disk to initialise the in-memory
1602 * structures.
1603 */
1604int jbd2_journal_load(journal_t *journal)
1605{
1606        int err;
1607        journal_superblock_t *sb;
1608
1609        err = load_superblock(journal);
1610        if (err)
1611                return err;
1612
1613        sb = journal->j_superblock;
1614        /* If this is a V2 superblock, then we have to check the
1615         * features flags on it. */
1616
1617        if (journal->j_format_version >= 2) {
1618                if ((sb->s_feature_ro_compat &
1619                     ~cpu_to_be32(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
1620                    (sb->s_feature_incompat &
1621                     ~cpu_to_be32(JBD2_KNOWN_INCOMPAT_FEATURES))) {
1622                        printk(KERN_WARNING
1623                                "JBD2: Unrecognised features on journal\n");
1624                        return -EINVAL;
1625                }
1626        }
1627
1628        /*
1629         * Create a slab for this blocksize
1630         */
1631        err = jbd2_journal_create_slab(be32_to_cpu(sb->s_blocksize));
1632        if (err)
1633                return err;
1634
1635        /* Let the recovery code check whether it needs to recover any
1636         * data from the journal. */
1637        if (jbd2_journal_recover(journal))
1638                goto recovery_error;
1639
1640        if (journal->j_failed_commit) {
1641                printk(KERN_ERR "JBD2: journal transaction %u on %s "
1642                       "is corrupt.\n", journal->j_failed_commit,
1643                       journal->j_devname);
1644                return -EIO;
1645        }
1646
1647        /* OK, we've finished with the dynamic journal bits:
1648         * reinitialise the dynamic contents of the superblock in memory
1649         * and reset them on disk. */
1650        if (journal_reset(journal))
1651                goto recovery_error;
1652
1653        journal->j_flags &= ~JBD2_ABORT;
1654        journal->j_flags |= JBD2_LOADED;
1655        return 0;
1656
1657recovery_error:
1658        printk(KERN_WARNING "JBD2: recovery failed\n");
1659        return -EIO;
1660}
1661
1662/**
1663 * void jbd2_journal_destroy() - Release a journal_t structure.
1664 * @journal: Journal to act on.
1665 *
1666 * Release a journal_t structure once it is no longer in use by the
1667 * journaled object.
1668 * Return <0 if we couldn't clean up the journal.
1669 */
1670int jbd2_journal_destroy(journal_t *journal)
1671{
1672        int err = 0;
1673
1674        /* Wait for the commit thread to wake up and die. */
1675        journal_kill_thread(journal);
1676
1677        /* Force a final log commit */
1678        if (journal->j_running_transaction)
1679                jbd2_journal_commit_transaction(journal);
1680
1681        /* Force any old transactions to disk */
1682
1683        /* Totally anal locking here... */
1684        spin_lock(&journal->j_list_lock);
1685        while (journal->j_checkpoint_transactions != NULL) {
1686                spin_unlock(&journal->j_list_lock);
1687                mutex_lock(&journal->j_checkpoint_mutex);
1688                jbd2_log_do_checkpoint(journal);
1689                mutex_unlock(&journal->j_checkpoint_mutex);
1690                spin_lock(&journal->j_list_lock);
1691        }
1692
1693        J_ASSERT(journal->j_running_transaction == NULL);
1694        J_ASSERT(journal->j_committing_transaction == NULL);
1695        J_ASSERT(journal->j_checkpoint_transactions == NULL);
1696        spin_unlock(&journal->j_list_lock);
1697
1698        if (journal->j_sb_buffer) {
1699                if (!is_journal_aborted(journal)) {
1700                        mutex_lock(&journal->j_checkpoint_mutex);
1701                        jbd2_mark_journal_empty(journal);
1702                        mutex_unlock(&journal->j_checkpoint_mutex);
1703                } else
1704                        err = -EIO;
1705                brelse(journal->j_sb_buffer);
1706        }
1707
1708        if (journal->j_proc_entry)
1709                jbd2_stats_proc_exit(journal);
1710        if (journal->j_inode)
1711                iput(journal->j_inode);
1712        if (journal->j_revoke)
1713                jbd2_journal_destroy_revoke(journal);
1714        if (journal->j_chksum_driver)
1715                crypto_free_shash(journal->j_chksum_driver);
1716        kfree(journal->j_wbuf);
1717        kfree(journal);
1718
1719        return err;
1720}
1721
1722
1723/**
1724 *int jbd2_journal_check_used_features () - Check if features specified are used.
1725 * @journal: Journal to check.
1726 * @compat: bitmask of compatible features
1727 * @ro: bitmask of features that force read-only mount
1728 * @incompat: bitmask of incompatible features
1729 *
1730 * Check whether the journal uses all of a given set of
1731 * features.  Return true (non-zero) if it does.
1732 **/
1733
1734int jbd2_journal_check_used_features (journal_t *journal, unsigned long compat,
1735                                 unsigned long ro, unsigned long incompat)
1736{
1737        journal_superblock_t *sb;
1738
1739        if (!compat && !ro && !incompat)
1740                return 1;
1741        /* Load journal superblock if it is not loaded yet. */
1742        if (journal->j_format_version == 0 &&
1743            journal_get_superblock(journal) != 0)
1744                return 0;
1745        if (journal->j_format_version == 1)
1746                return 0;
1747
1748        sb = journal->j_superblock;
1749
1750        if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1751            ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1752            ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1753                return 1;
1754
1755        return 0;
1756}
1757
1758/**
1759 * int jbd2_journal_check_available_features() - Check feature set in journalling layer
1760 * @journal: Journal to check.
1761 * @compat: bitmask of compatible features
1762 * @ro: bitmask of features that force read-only mount
1763 * @incompat: bitmask of incompatible features
1764 *
1765 * Check whether the journaling code supports the use of
1766 * all of a given set of features on this journal.  Return true
1767 * (non-zero) if it can. */
1768
1769int jbd2_journal_check_available_features (journal_t *journal, unsigned long compat,
1770                                      unsigned long ro, unsigned long incompat)
1771{
1772        if (!compat && !ro && !incompat)
1773                return 1;
1774
1775        /* We can support any known requested features iff the
1776         * superblock is in version 2.  Otherwise we fail to support any
1777         * extended sb features. */
1778
1779        if (journal->j_format_version != 2)
1780                return 0;
1781
1782        if ((compat   & JBD2_KNOWN_COMPAT_FEATURES) == compat &&
1783            (ro       & JBD2_KNOWN_ROCOMPAT_FEATURES) == ro &&
1784            (incompat & JBD2_KNOWN_INCOMPAT_FEATURES) == incompat)
1785                return 1;
1786
1787        return 0;
1788}
1789
1790/**
1791 * int jbd2_journal_set_features () - Mark a given journal feature in the superblock
1792 * @journal: Journal to act on.
1793 * @compat: bitmask of compatible features
1794 * @ro: bitmask of features that force read-only mount
1795 * @incompat: bitmask of incompatible features
1796 *
1797 * Mark a given journal feature as present on the
1798 * superblock.  Returns true if the requested features could be set.
1799 *
1800 */
1801
1802int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
1803                          unsigned long ro, unsigned long incompat)
1804{
1805#define INCOMPAT_FEATURE_ON(f) \
1806                ((incompat & (f)) && !(sb->s_feature_incompat & cpu_to_be32(f)))
1807#define COMPAT_FEATURE_ON(f) \
1808                ((compat & (f)) && !(sb->s_feature_compat & cpu_to_be32(f)))
1809        journal_superblock_t *sb;
1810
1811        if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
1812                return 1;
1813
1814        if (!jbd2_journal_check_available_features(journal, compat, ro, incompat))
1815                return 0;
1816
1817        /* Asking for checksumming v2 and v1?  Only give them v2. */
1818        if (incompat & JBD2_FEATURE_INCOMPAT_CSUM_V2 &&
1819            compat & JBD2_FEATURE_COMPAT_CHECKSUM)
1820                compat &= ~JBD2_FEATURE_COMPAT_CHECKSUM;
1821
1822        jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1823                  compat, ro, incompat);
1824
1825        sb = journal->j_superblock;
1826
1827        /* If enabling v2 checksums, update superblock */
1828        if (INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
1829                sb->s_checksum_type = JBD2_CRC32C_CHKSUM;
1830                sb->s_feature_compat &=
1831                        ~cpu_to_be32(JBD2_FEATURE_COMPAT_CHECKSUM);
1832
1833                /* Load the checksum driver */
1834                if (journal->j_chksum_driver == NULL) {
1835                        journal->j_chksum_driver = crypto_alloc_shash("crc32c",
1836                                                                      0, 0);
1837                        if (IS_ERR(journal->j_chksum_driver)) {
1838                                printk(KERN_ERR "JBD: Cannot load crc32c "
1839                                       "driver.\n");
1840                                journal->j_chksum_driver = NULL;
1841                                return 0;
1842                        }
1843                }
1844
1845                /* Precompute checksum seed for all metadata */
1846                if (JBD2_HAS_INCOMPAT_FEATURE(journal,
1847                                              JBD2_FEATURE_INCOMPAT_CSUM_V2))
1848                        journal->j_csum_seed = jbd2_chksum(journal, ~0,
1849                                                           sb->s_uuid,
1850                                                           sizeof(sb->s_uuid));
1851        }
1852
1853        /* If enabling v1 checksums, downgrade superblock */
1854        if (COMPAT_FEATURE_ON(JBD2_FEATURE_COMPAT_CHECKSUM))
1855                sb->s_feature_incompat &=
1856                        ~cpu_to_be32(JBD2_FEATURE_INCOMPAT_CSUM_V2);
1857
1858        sb->s_feature_compat    |= cpu_to_be32(compat);
1859        sb->s_feature_ro_compat |= cpu_to_be32(ro);
1860        sb->s_feature_incompat  |= cpu_to_be32(incompat);
1861
1862        return 1;
1863#undef COMPAT_FEATURE_ON
1864#undef INCOMPAT_FEATURE_ON
1865}
1866
1867/*
1868 * jbd2_journal_clear_features () - Clear a given journal feature in the
1869 *                                  superblock
1870 * @journal: Journal to act on.
1871 * @compat: bitmask of compatible features
1872 * @ro: bitmask of features that force read-only mount
1873 * @incompat: bitmask of incompatible features
1874 *
1875 * Clear a given journal feature as present on the
1876 * superblock.
1877 */
1878void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
1879                                unsigned long ro, unsigned long incompat)
1880{
1881        journal_superblock_t *sb;
1882
1883        jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
1884                  compat, ro, incompat);
1885
1886        sb = journal->j_superblock;
1887
1888        sb->s_feature_compat    &= ~cpu_to_be32(compat);
1889        sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
1890        sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
1891}
1892EXPORT_SYMBOL(jbd2_journal_clear_features);
1893
1894/**
1895 * int jbd2_journal_flush () - Flush journal
1896 * @journal: Journal to act on.
1897 *
1898 * Flush all data for a given journal to disk and empty the journal.
1899 * Filesystems can use this when remounting readonly to ensure that
1900 * recovery does not need to happen on remount.
1901 */
1902
1903int jbd2_journal_flush(journal_t *journal)
1904{
1905        int err = 0;
1906        transaction_t *transaction = NULL;
1907
1908        write_lock(&journal->j_state_lock);
1909
1910        /* Force everything buffered to the log... */
1911        if (journal->j_running_transaction) {
1912                transaction = journal->j_running_transaction;
1913                __jbd2_log_start_commit(journal, transaction->t_tid);
1914        } else if (journal->j_committing_transaction)
1915                transaction = journal->j_committing_transaction;
1916
1917        /* Wait for the log commit to complete... */
1918        if (transaction) {
1919                tid_t tid = transaction->t_tid;
1920
1921                write_unlock(&journal->j_state_lock);
1922                jbd2_log_wait_commit(journal, tid);
1923        } else {
1924                write_unlock(&journal->j_state_lock);
1925        }
1926
1927        /* ...and flush everything in the log out to disk. */
1928        spin_lock(&journal->j_list_lock);
1929        while (!err && journal->j_checkpoint_transactions != NULL) {
1930                spin_unlock(&journal->j_list_lock);
1931                mutex_lock(&journal->j_checkpoint_mutex);
1932                err = jbd2_log_do_checkpoint(journal);
1933                mutex_unlock(&journal->j_checkpoint_mutex);
1934                spin_lock(&journal->j_list_lock);
1935        }
1936        spin_unlock(&journal->j_list_lock);
1937
1938        if (is_journal_aborted(journal))
1939                return -EIO;
1940
1941        mutex_lock(&journal->j_checkpoint_mutex);
1942        jbd2_cleanup_journal_tail(journal);
1943
1944        /* Finally, mark the journal as really needing no recovery.
1945         * This sets s_start==0 in the underlying superblock, which is
1946         * the magic code for a fully-recovered superblock.  Any future
1947         * commits of data to the journal will restore the current
1948         * s_start value. */
1949        jbd2_mark_journal_empty(journal);
1950        mutex_unlock(&journal->j_checkpoint_mutex);
1951        write_lock(&journal->j_state_lock);
1952        J_ASSERT(!journal->j_running_transaction);
1953        J_ASSERT(!journal->j_committing_transaction);
1954        J_ASSERT(!journal->j_checkpoint_transactions);
1955        J_ASSERT(journal->j_head == journal->j_tail);
1956        J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1957        write_unlock(&journal->j_state_lock);
1958        return 0;
1959}
1960
1961/**
1962 * int jbd2_journal_wipe() - Wipe journal contents
1963 * @journal: Journal to act on.
1964 * @write: flag (see below)
1965 *
1966 * Wipe out all of the contents of a journal, safely.  This will produce
1967 * a warning if the journal contains any valid recovery information.
1968 * Must be called between journal_init_*() and jbd2_journal_load().
1969 *
1970 * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
1971 * we merely suppress recovery.
1972 */
1973
1974int jbd2_journal_wipe(journal_t *journal, int write)
1975{
1976        int err = 0;
1977
1978        J_ASSERT (!(journal->j_flags & JBD2_LOADED));
1979
1980        err = load_superblock(journal);
1981        if (err)
1982                return err;
1983
1984        if (!journal->j_tail)
1985                goto no_recovery;
1986
1987        printk(KERN_WARNING "JBD2: %s recovery information on journal\n",
1988                write ? "Clearing" : "Ignoring");
1989
1990        err = jbd2_journal_skip_recovery(journal);
1991        if (write) {
1992                /* Lock to make assertions happy... */
1993                mutex_lock(&journal->j_checkpoint_mutex);
1994                jbd2_mark_journal_empty(journal);
1995                mutex_unlock(&journal->j_checkpoint_mutex);
1996        }
1997
1998 no_recovery:
1999        return err;
2000}
2001
2002/*
2003 * Journal abort has very specific semantics, which we describe
2004 * for journal abort.
2005 *
2006 * Two internal functions, which provide abort to the jbd layer
2007 * itself are here.
2008 */
2009
2010/*
2011 * Quick version for internal journal use (doesn't lock the journal).
2012 * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
2013 * and don't attempt to make any other journal updates.
2014 */
2015void __jbd2_journal_abort_hard(journal_t *journal)
2016{
2017        transaction_t *transaction;
2018
2019        if (journal->j_flags & JBD2_ABORT)
2020                return;
2021
2022        printk(KERN_ERR "Aborting journal on device %s.\n",
2023               journal->j_devname);
2024
2025        write_lock(&journal->j_state_lock);
2026        journal->j_flags |= JBD2_ABORT;
2027        transaction = journal->j_running_transaction;
2028        if (transaction)
2029                __jbd2_log_start_commit(journal, transaction->t_tid);
2030        write_unlock(&journal->j_state_lock);
2031}
2032
2033/* Soft abort: record the abort error status in the journal superblock,
2034 * but don't do any other IO. */
2035static void __journal_abort_soft (journal_t *journal, int errno)
2036{
2037        if (journal->j_flags & JBD2_ABORT)
2038                return;
2039
2040        if (!journal->j_errno)
2041                journal->j_errno = errno;
2042
2043        __jbd2_journal_abort_hard(journal);
2044
2045        if (errno)
2046                jbd2_journal_update_sb_errno(journal);
2047}
2048
2049/**
2050 * void jbd2_journal_abort () - Shutdown the journal immediately.
2051 * @journal: the journal to shutdown.
2052 * @errno:   an error number to record in the journal indicating
2053 *           the reason for the shutdown.
2054 *
2055 * Perform a complete, immediate shutdown of the ENTIRE
2056 * journal (not of a single transaction).  This operation cannot be
2057 * undone without closing and reopening the journal.
2058 *
2059 * The jbd2_journal_abort function is intended to support higher level error
2060 * recovery mechanisms such as the ext2/ext3 remount-readonly error
2061 * mode.
2062 *
2063 * Journal abort has very specific semantics.  Any existing dirty,
2064 * unjournaled buffers in the main filesystem will still be written to
2065 * disk by bdflush, but the journaling mechanism will be suspended
2066 * immediately and no further transaction commits will be honoured.
2067 *
2068 * Any dirty, journaled buffers will be written back to disk without
2069 * hitting the journal.  Atomicity cannot be guaranteed on an aborted
2070 * filesystem, but we _do_ attempt to leave as much data as possible
2071 * behind for fsck to use for cleanup.
2072 *
2073 * Any attempt to get a new transaction handle on a journal which is in
2074 * ABORT state will just result in an -EROFS error return.  A
2075 * jbd2_journal_stop on an existing handle will return -EIO if we have
2076 * entered abort state during the update.
2077 *
2078 * Recursive transactions are not disturbed by journal abort until the
2079 * final jbd2_journal_stop, which will receive the -EIO error.
2080 *
2081 * Finally, the jbd2_journal_abort call allows the caller to supply an errno
2082 * which will be recorded (if possible) in the journal superblock.  This
2083 * allows a client to record failure conditions in the middle of a
2084 * transaction without having to complete the transaction to record the
2085 * failure to disk.  ext3_error, for example, now uses this
2086 * functionality.
2087 *
2088 * Errors which originate from within the journaling layer will NOT
2089 * supply an errno; a null errno implies that absolutely no further
2090 * writes are done to the journal (unless there are any already in
2091 * progress).
2092 *
2093 */
2094
2095void jbd2_journal_abort(journal_t *journal, int errno)
2096{
2097        __journal_abort_soft(journal, errno);
2098}
2099
2100/**
2101 * int jbd2_journal_errno () - returns the journal's error state.
2102 * @journal: journal to examine.
2103 *
2104 * This is the errno number set with jbd2_journal_abort(), the last
2105 * time the journal was mounted - if the journal was stopped
2106 * without calling abort this will be 0.
2107 *
2108 * If the journal has been aborted on this mount time -EROFS will
2109 * be returned.
2110 */
2111int jbd2_journal_errno(journal_t *journal)
2112{
2113        int err;
2114
2115        read_lock(&journal->j_state_lock);
2116        if (journal->j_flags & JBD2_ABORT)
2117                err = -EROFS;
2118        else
2119                err = journal->j_errno;
2120        read_unlock(&journal->j_state_lock);
2121        return err;
2122}
2123
2124/**
2125 * int jbd2_journal_clear_err () - clears the journal's error state
2126 * @journal: journal to act on.
2127 *
2128 * An error must be cleared or acked to take a FS out of readonly
2129 * mode.
2130 */
2131int jbd2_journal_clear_err(journal_t *journal)
2132{
2133        int err = 0;
2134
2135        write_lock(&journal->j_state_lock);
2136        if (journal->j_flags & JBD2_ABORT)
2137                err = -EROFS;
2138        else
2139                journal->j_errno = 0;
2140        write_unlock(&journal->j_state_lock);
2141        return err;
2142}
2143
2144/**
2145 * void jbd2_journal_ack_err() - Ack journal err.
2146 * @journal: journal to act on.
2147 *
2148 * An error must be cleared or acked to take a FS out of readonly
2149 * mode.
2150 */
2151void jbd2_journal_ack_err(journal_t *journal)
2152{
2153        write_lock(&journal->j_state_lock);
2154        if (journal->j_errno)
2155                journal->j_flags |= JBD2_ACK_ERR;
2156        write_unlock(&journal->j_state_lock);
2157}
2158
2159int jbd2_journal_blocks_per_page(struct inode *inode)
2160{
2161        return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
2162}
2163
2164/*
2165 * helper functions to deal with 32 or 64bit block numbers.
2166 */
2167size_t journal_tag_bytes(journal_t *journal)
2168{
2169        journal_block_tag_t tag;
2170        size_t x = 0;
2171
2172        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
2173                x += sizeof(tag.t_checksum);
2174
2175        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
2176                return x + JBD2_TAG_SIZE64;
2177        else
2178                return x + JBD2_TAG_SIZE32;
2179}
2180
2181/*
2182 * JBD memory management
2183 *
2184 * These functions are used to allocate block-sized chunks of memory
2185 * used for making copies of buffer_head data.  Very often it will be
2186 * page-sized chunks of data, but sometimes it will be in
2187 * sub-page-size chunks.  (For example, 16k pages on Power systems
2188 * with a 4k block file system.)  For blocks smaller than a page, we
2189 * use a SLAB allocator.  There are slab caches for each block size,
2190 * which are allocated at mount time, if necessary, and we only free
2191 * (all of) the slab caches when/if the jbd2 module is unloaded.  For
2192 * this reason we don't need to a mutex to protect access to
2193 * jbd2_slab[] allocating or releasing memory; only in
2194 * jbd2_journal_create_slab().
2195 */
2196#define JBD2_MAX_SLABS 8
2197static struct kmem_cache *jbd2_slab[JBD2_MAX_SLABS];
2198
2199static const char *jbd2_slab_names[JBD2_MAX_SLABS] = {
2200        "jbd2_1k", "jbd2_2k", "jbd2_4k", "jbd2_8k",
2201        "jbd2_16k", "jbd2_32k", "jbd2_64k", "jbd2_128k"
2202};
2203
2204
2205static void jbd2_journal_destroy_slabs(void)
2206{
2207        int i;
2208
2209        for (i = 0; i < JBD2_MAX_SLABS; i++) {
2210                if (jbd2_slab[i])
2211                        kmem_cache_destroy(jbd2_slab[i]);
2212                jbd2_slab[i] = NULL;
2213        }
2214}
2215
2216static int jbd2_journal_create_slab(size_t size)
2217{
2218        static DEFINE_MUTEX(jbd2_slab_create_mutex);
2219        int i = order_base_2(size) - 10;
2220        size_t slab_size;
2221
2222        if (size == PAGE_SIZE)
2223                return 0;
2224
2225        if (i >= JBD2_MAX_SLABS)
2226                return -EINVAL;
2227
2228        if (unlikely(i < 0))
2229                i = 0;
2230        mutex_lock(&jbd2_slab_create_mutex);
2231        if (jbd2_slab[i]) {
2232                mutex_unlock(&jbd2_slab_create_mutex);
2233                return 0;       /* Already created */
2234        }
2235
2236        slab_size = 1 << (i+10);
2237        jbd2_slab[i] = kmem_cache_create(jbd2_slab_names[i], slab_size,
2238                                         slab_size, 0, NULL);
2239        mutex_unlock(&jbd2_slab_create_mutex);
2240        if (!jbd2_slab[i]) {
2241                printk(KERN_EMERG "JBD2: no memory for jbd2_slab cache\n");
2242                return -ENOMEM;
2243        }
2244        return 0;
2245}
2246
2247static struct kmem_cache *get_slab(size_t size)
2248{
2249        int i = order_base_2(size) - 10;
2250
2251        BUG_ON(i >= JBD2_MAX_SLABS);
2252        if (unlikely(i < 0))
2253                i = 0;
2254        BUG_ON(jbd2_slab[i] == NULL);
2255        return jbd2_slab[i];
2256}
2257
2258void *jbd2_alloc(size_t size, gfp_t flags)
2259{
2260        void *ptr;
2261
2262        BUG_ON(size & (size-1)); /* Must be a power of 2 */
2263
2264        flags |= __GFP_REPEAT;
2265        if (size == PAGE_SIZE)
2266                ptr = (void *)__get_free_pages(flags, 0);
2267        else if (size > PAGE_SIZE) {
2268                int order = get_order(size);
2269
2270                if (order < 3)
2271                        ptr = (void *)__get_free_pages(flags, order);
2272                else
2273                        ptr = vmalloc(size);
2274        } else
2275                ptr = kmem_cache_alloc(get_slab(size), flags);
2276
2277        /* Check alignment; SLUB has gotten this wrong in the past,
2278         * and this can lead to user data corruption! */
2279        BUG_ON(((unsigned long) ptr) & (size-1));
2280
2281        return ptr;
2282}
2283
2284void jbd2_free(void *ptr, size_t size)
2285{
2286        if (size == PAGE_SIZE) {
2287                free_pages((unsigned long)ptr, 0);
2288                return;
2289        }
2290        if (size > PAGE_SIZE) {
2291                int order = get_order(size);
2292
2293                if (order < 3)
2294                        free_pages((unsigned long)ptr, order);
2295                else
2296                        vfree(ptr);
2297                return;
2298        }
2299        kmem_cache_free(get_slab(size), ptr);
2300};
2301
2302/*
2303 * Journal_head storage management
2304 */
2305static struct kmem_cache *jbd2_journal_head_cache;
2306#ifdef CONFIG_JBD2_DEBUG
2307static atomic_t nr_journal_heads = ATOMIC_INIT(0);
2308#endif
2309
2310static int jbd2_journal_init_journal_head_cache(void)
2311{
2312        int retval;
2313
2314        J_ASSERT(jbd2_journal_head_cache == NULL);
2315        jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
2316                                sizeof(struct journal_head),
2317                                0,              /* offset */
2318                                SLAB_TEMPORARY, /* flags */
2319                                NULL);          /* ctor */
2320        retval = 0;
2321        if (!jbd2_journal_head_cache) {
2322                retval = -ENOMEM;
2323                printk(KERN_EMERG "JBD2: no memory for journal_head cache\n");
2324        }
2325        return retval;
2326}
2327
2328static void jbd2_journal_destroy_journal_head_cache(void)
2329{
2330        if (jbd2_journal_head_cache) {
2331                kmem_cache_destroy(jbd2_journal_head_cache);
2332                jbd2_journal_head_cache = NULL;
2333        }
2334}
2335
2336/*
2337 * journal_head splicing and dicing
2338 */
2339static struct journal_head *journal_alloc_journal_head(void)
2340{
2341        struct journal_head *ret;
2342
2343#ifdef CONFIG_JBD2_DEBUG
2344        atomic_inc(&nr_journal_heads);
2345#endif
2346        ret = kmem_cache_zalloc(jbd2_journal_head_cache, GFP_NOFS);
2347        if (!ret) {
2348                jbd_debug(1, "out of memory for journal_head\n");
2349                pr_notice_ratelimited("ENOMEM in %s, retrying.\n", __func__);
2350                while (!ret) {
2351                        yield();
2352                        ret = kmem_cache_zalloc(jbd2_journal_head_cache, GFP_NOFS);
2353                }
2354        }
2355        return ret;
2356}
2357
2358static void journal_free_journal_head(struct journal_head *jh)
2359{
2360#ifdef CONFIG_JBD2_DEBUG
2361        atomic_dec(&nr_journal_heads);
2362        memset(jh, JBD2_POISON_FREE, sizeof(*jh));
2363#endif
2364        kmem_cache_free(jbd2_journal_head_cache, jh);
2365}
2366
2367/*
2368 * A journal_head is attached to a buffer_head whenever JBD has an
2369 * interest in the buffer.
2370 *
2371 * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
2372 * is set.  This bit is tested in core kernel code where we need to take
2373 * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
2374 * there.
2375 *
2376 * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
2377 *
2378 * When a buffer has its BH_JBD bit set it is immune from being released by
2379 * core kernel code, mainly via ->b_count.
2380 *
2381 * A journal_head is detached from its buffer_head when the journal_head's
2382 * b_jcount reaches zero. Running transaction (b_transaction) and checkpoint
2383 * transaction (b_cp_transaction) hold their references to b_jcount.
2384 *
2385 * Various places in the kernel want to attach a journal_head to a buffer_head
2386 * _before_ attaching the journal_head to a transaction.  To protect the
2387 * journal_head in this situation, jbd2_journal_add_journal_head elevates the
2388 * journal_head's b_jcount refcount by one.  The caller must call
2389 * jbd2_journal_put_journal_head() to undo this.
2390 *
2391 * So the typical usage would be:
2392 *
2393 *      (Attach a journal_head if needed.  Increments b_jcount)
2394 *      struct journal_head *jh = jbd2_journal_add_journal_head(bh);
2395 *      ...
2396 *      (Get another reference for transaction)
2397 *      jbd2_journal_grab_journal_head(bh);
2398 *      jh->b_transaction = xxx;
2399 *      (Put original reference)
2400 *      jbd2_journal_put_journal_head(jh);
2401 */
2402
2403/*
2404 * Give a buffer_head a journal_head.
2405 *
2406 * May sleep.
2407 */
2408struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh)
2409{
2410        struct journal_head *jh;
2411        struct journal_head *new_jh = NULL;
2412
2413repeat:
2414        if (!buffer_jbd(bh))
2415                new_jh = journal_alloc_journal_head();
2416
2417        jbd_lock_bh_journal_head(bh);
2418        if (buffer_jbd(bh)) {
2419                jh = bh2jh(bh);
2420        } else {
2421                J_ASSERT_BH(bh,
2422                        (atomic_read(&bh->b_count) > 0) ||
2423                        (bh->b_page && bh->b_page->mapping));
2424
2425                if (!new_jh) {
2426                        jbd_unlock_bh_journal_head(bh);
2427                        goto repeat;
2428                }
2429
2430                jh = new_jh;
2431                new_jh = NULL;          /* We consumed it */
2432                set_buffer_jbd(bh);
2433                bh->b_private = jh;
2434                jh->b_bh = bh;
2435                get_bh(bh);
2436                BUFFER_TRACE(bh, "added journal_head");
2437        }
2438        jh->b_jcount++;
2439        jbd_unlock_bh_journal_head(bh);
2440        if (new_jh)
2441                journal_free_journal_head(new_jh);
2442        return bh->b_private;
2443}
2444
2445/*
2446 * Grab a ref against this buffer_head's journal_head.  If it ended up not
2447 * having a journal_head, return NULL
2448 */
2449struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh)
2450{
2451        struct journal_head *jh = NULL;
2452
2453        jbd_lock_bh_journal_head(bh);
2454        if (buffer_jbd(bh)) {
2455                jh = bh2jh(bh);
2456                jh->b_jcount++;
2457        }
2458        jbd_unlock_bh_journal_head(bh);
2459        return jh;
2460}
2461
2462static void __journal_remove_journal_head(struct buffer_head *bh)
2463{
2464        struct journal_head *jh = bh2jh(bh);
2465
2466        J_ASSERT_JH(jh, jh->b_jcount >= 0);
2467        J_ASSERT_JH(jh, jh->b_transaction == NULL);
2468        J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
2469        J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
2470        J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
2471        J_ASSERT_BH(bh, buffer_jbd(bh));
2472        J_ASSERT_BH(bh, jh2bh(jh) == bh);
2473        BUFFER_TRACE(bh, "remove journal_head");
2474        if (jh->b_frozen_data) {
2475                printk(KERN_WARNING "%s: freeing b_frozen_data\n", __func__);
2476                jbd2_free(jh->b_frozen_data, bh->b_size);
2477        }
2478        if (jh->b_committed_data) {
2479                printk(KERN_WARNING "%s: freeing b_committed_data\n", __func__);
2480                jbd2_free(jh->b_committed_data, bh->b_size);
2481        }
2482        bh->b_private = NULL;
2483        jh->b_bh = NULL;        /* debug, really */
2484        clear_buffer_jbd(bh);
2485        journal_free_journal_head(jh);
2486}
2487
2488/*
2489 * Drop a reference on the passed journal_head.  If it fell to zero then
2490 * release the journal_head from the buffer_head.
2491 */
2492void jbd2_journal_put_journal_head(struct journal_head *jh)
2493{
2494        struct buffer_head *bh = jh2bh(jh);
2495
2496        jbd_lock_bh_journal_head(bh);
2497        J_ASSERT_JH(jh, jh->b_jcount > 0);
2498        --jh->b_jcount;
2499        if (!jh->b_jcount) {
2500                __journal_remove_journal_head(bh);
2501                jbd_unlock_bh_journal_head(bh);
2502                __brelse(bh);
2503        } else
2504                jbd_unlock_bh_journal_head(bh);
2505}
2506
2507/*
2508 * Initialize jbd inode head
2509 */
2510void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode)
2511{
2512        jinode->i_transaction = NULL;
2513        jinode->i_next_transaction = NULL;
2514        jinode->i_vfs_inode = inode;
2515        jinode->i_flags = 0;
2516        INIT_LIST_HEAD(&jinode->i_list);
2517}
2518
2519/*
2520 * Function to be called before we start removing inode from memory (i.e.,
2521 * clear_inode() is a fine place to be called from). It removes inode from
2522 * transaction's lists.
2523 */
2524void jbd2_journal_release_jbd_inode(journal_t *journal,
2525                                    struct jbd2_inode *jinode)
2526{
2527        if (!journal)
2528                return;
2529restart:
2530        spin_lock(&journal->j_list_lock);
2531        /* Is commit writing out inode - we have to wait */
2532        if (test_bit(__JI_COMMIT_RUNNING, &jinode->i_flags)) {
2533                wait_queue_head_t *wq;
2534                DEFINE_WAIT_BIT(wait, &jinode->i_flags, __JI_COMMIT_RUNNING);
2535                wq = bit_waitqueue(&jinode->i_flags, __JI_COMMIT_RUNNING);
2536                prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
2537                spin_unlock(&journal->j_list_lock);
2538                schedule();
2539                finish_wait(wq, &wait.wait);
2540                goto restart;
2541        }
2542
2543        if (jinode->i_transaction) {
2544                list_del(&jinode->i_list);
2545                jinode->i_transaction = NULL;
2546        }
2547        spin_unlock(&journal->j_list_lock);
2548}
2549
2550
2551#ifdef CONFIG_PROC_FS
2552
2553#define JBD2_STATS_PROC_NAME "fs/jbd2"
2554
2555static void __init jbd2_create_jbd_stats_proc_entry(void)
2556{
2557        proc_jbd2_stats = proc_mkdir(JBD2_STATS_PROC_NAME, NULL);
2558}
2559
2560static void __exit jbd2_remove_jbd_stats_proc_entry(void)
2561{
2562        if (proc_jbd2_stats)
2563                remove_proc_entry(JBD2_STATS_PROC_NAME, NULL);
2564}
2565
2566#else
2567
2568#define jbd2_create_jbd_stats_proc_entry() do {} while (0)
2569#define jbd2_remove_jbd_stats_proc_entry() do {} while (0)
2570
2571#endif
2572
2573struct kmem_cache *jbd2_handle_cache, *jbd2_inode_cache;
2574
2575static int __init jbd2_journal_init_handle_cache(void)
2576{
2577        jbd2_handle_cache = KMEM_CACHE(jbd2_journal_handle, SLAB_TEMPORARY);
2578        if (jbd2_handle_cache == NULL) {
2579                printk(KERN_EMERG "JBD2: failed to create handle cache\n");
2580                return -ENOMEM;
2581        }
2582        jbd2_inode_cache = KMEM_CACHE(jbd2_inode, 0);
2583        if (jbd2_inode_cache == NULL) {
2584                printk(KERN_EMERG "JBD2: failed to create inode cache\n");
2585                kmem_cache_destroy(jbd2_handle_cache);
2586                return -ENOMEM;
2587        }
2588        return 0;
2589}
2590
2591static void jbd2_journal_destroy_handle_cache(void)
2592{
2593        if (jbd2_handle_cache)
2594                kmem_cache_destroy(jbd2_handle_cache);
2595        if (jbd2_inode_cache)
2596                kmem_cache_destroy(jbd2_inode_cache);
2597
2598}
2599
2600/*
2601 * Module startup and shutdown
2602 */
2603
2604static int __init journal_init_caches(void)
2605{
2606        int ret;
2607
2608        ret = jbd2_journal_init_revoke_caches();
2609        if (ret == 0)
2610                ret = jbd2_journal_init_journal_head_cache();
2611        if (ret == 0)
2612                ret = jbd2_journal_init_handle_cache();
2613        if (ret == 0)
2614                ret = jbd2_journal_init_transaction_cache();
2615        return ret;
2616}
2617
2618static void jbd2_journal_destroy_caches(void)
2619{
2620        jbd2_journal_destroy_revoke_caches();
2621        jbd2_journal_destroy_journal_head_cache();
2622        jbd2_journal_destroy_handle_cache();
2623        jbd2_journal_destroy_transaction_cache();
2624        jbd2_journal_destroy_slabs();
2625}
2626
2627static int __init journal_init(void)
2628{
2629        int ret;
2630
2631        BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
2632
2633        ret = journal_init_caches();
2634        if (ret == 0) {
2635                jbd2_create_jbd_stats_proc_entry();
2636        } else {
2637                jbd2_journal_destroy_caches();
2638        }
2639        return ret;
2640}
2641
2642static void __exit journal_exit(void)
2643{
2644#ifdef CONFIG_JBD2_DEBUG
2645        int n = atomic_read(&nr_journal_heads);
2646        if (n)
2647                printk(KERN_EMERG "JBD2: leaked %d journal_heads!\n", n);
2648#endif
2649        jbd2_remove_jbd_stats_proc_entry();
2650        jbd2_journal_destroy_caches();
2651}
2652
2653MODULE_LICENSE("GPL");
2654module_init(journal_init);
2655module_exit(journal_exit);
2656
2657
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