fs/jbd2/journal.c

   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/debugfs.h>
  39 #include <linux/seq_file.h>
  40
  41 #include <asm/uaccess.h>
  42 #include <asm/page.h>
  43
  44 EXPORT_SYMBOL(jbd2_journal_start);
  45 EXPORT_SYMBOL(jbd2_journal_restart);
  46 EXPORT_SYMBOL(jbd2_journal_extend);
  47 EXPORT_SYMBOL(jbd2_journal_stop);
  48 EXPORT_SYMBOL(jbd2_journal_lock_updates);
  49 EXPORT_SYMBOL(jbd2_journal_unlock_updates);
  50 EXPORT_SYMBOL(jbd2_journal_get_write_access);
  51 EXPORT_SYMBOL(jbd2_journal_get_create_access);
  52 EXPORT_SYMBOL(jbd2_journal_get_undo_access);
  53 EXPORT_SYMBOL(jbd2_journal_dirty_metadata);
  54 EXPORT_SYMBOL(jbd2_journal_release_buffer);
  55 EXPORT_SYMBOL(jbd2_journal_forget);
  56 #if 0
  57 EXPORT_SYMBOL(journal_sync_buffer);
  58 #endif
  59 EXPORT_SYMBOL(jbd2_journal_flush);
  60 EXPORT_SYMBOL(jbd2_journal_revoke);
  61
  62 EXPORT_SYMBOL(jbd2_journal_init_dev);
  63 EXPORT_SYMBOL(jbd2_journal_init_inode);
  64 EXPORT_SYMBOL(jbd2_journal_update_format);
  65 EXPORT_SYMBOL(jbd2_journal_check_used_features);
  66 EXPORT_SYMBOL(jbd2_journal_check_available_features);
  67 EXPORT_SYMBOL(jbd2_journal_set_features);
  68 EXPORT_SYMBOL(jbd2_journal_create);
  69 EXPORT_SYMBOL(jbd2_journal_load);
  70 EXPORT_SYMBOL(jbd2_journal_destroy);
  71 EXPORT_SYMBOL(jbd2_journal_abort);
  72 EXPORT_SYMBOL(jbd2_journal_errno);
  73 EXPORT_SYMBOL(jbd2_journal_ack_err);
  74 EXPORT_SYMBOL(jbd2_journal_clear_err);
  75 EXPORT_SYMBOL(jbd2_log_wait_commit);
  76 EXPORT_SYMBOL(jbd2_journal_start_commit);
  77 EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
  78 EXPORT_SYMBOL(jbd2_journal_wipe);
  79 EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
  80 EXPORT_SYMBOL(jbd2_journal_invalidatepage);
  81 EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
  82 EXPORT_SYMBOL(jbd2_journal_force_commit);
  83 EXPORT_SYMBOL(jbd2_journal_file_inode);
  84 EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
  85 EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
  86 EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
  87
  88 static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
  89 static void __journal_abort_soft (journal_t *journal, int errno);
  90
  91 /*
  92  * Helper function used to manage commit timeouts
  93  */
  94
  95 static void commit_timeout(unsigned long __data)
  96 {
  97         struct task_struct * p = (struct task_struct *) __data;
  98
  99         wake_up_process(p);
 100 }
 101
 102 /*
 103  * kjournald2: The main thread function used to manage a logging device
 104  * journal.
 105  *
 106  * This kernel thread is responsible for two things:
 107  *
 108  * 1) COMMIT:  Every so often we need to commit the current state of the
 109  *    filesystem to disk.  The journal thread is responsible for writing
 110  *    all of the metadata buffers to disk.
 111  *
 112  * 2) CHECKPOINT: We cannot reuse a used section of the log file until all
 113  *    of the data in that part of the log has been rewritten elsewhere on
 114  *    the disk.  Flushing these old buffers to reclaim space in the log is
 115  *    known as checkpointing, and this thread is responsible for that job.
 116  */
 117
 118 static int kjournald2(void *arg)
 119 {
 120         journal_t *journal = arg;
 121         transaction_t *transaction;
 122
 123         /*
 124          * Set up an interval timer which can be used to trigger a commit wakeup
 125          * after the commit interval expires
 126          */
 127         setup_timer(&journal->j_commit_timer, commit_timeout,
 128                         (unsigned long)current);
 129
 130         /* Record that the journal thread is running */
 131         journal->j_task = current;
 132         wake_up(&journal->j_wait_done_commit);
 133
 134         printk(KERN_INFO "kjournald2 starting.  Commit interval %ld seconds\n",
 135                         journal->j_commit_interval / HZ);
 136
 137         /*
 138          * And now, wait forever for commit wakeup events.
 139          */
 140         spin_lock(&journal->j_state_lock);
 141
 142 loop:
 143         if (journal->j_flags & JBD2_UNMOUNT)
 144                 goto end_loop;
 145
 146         jbd_debug(1, "commit_sequence=%d, commit_request=%d\n",
 147                 journal->j_commit_sequence, journal->j_commit_request);
 148
 149         if (journal->j_commit_sequence != journal->j_commit_request) {
 150                 jbd_debug(1, "OK, requests differ\n");
 151                 spin_unlock(&journal->j_state_lock);
 152                 del_timer_sync(&journal->j_commit_timer);
 153                 jbd2_journal_commit_transaction(journal);
 154                 spin_lock(&journal->j_state_lock);
 155                 goto loop;
 156         }
 157
 158         wake_up(&journal->j_wait_done_commit);
 159         if (freezing(current)) {
 160                 /*
 161                  * The simpler the better. Flushing journal isn't a
 162                  * good idea, because that depends on threads that may
 163                  * be already stopped.
 164                  */
 165                 jbd_debug(1, "Now suspending kjournald2\n");
 166                 spin_unlock(&journal->j_state_lock);
 167                 refrigerator();
 168                 spin_lock(&journal->j_state_lock);
 169         } else {
 170                 /*
 171                  * We assume on resume that commits are already there,
 172                  * so we don't sleep
 173                  */
 174                 DEFINE_WAIT(wait);
 175                 int should_sleep = 1;
 176
 177                 prepare_to_wait(&journal->j_wait_commit, &wait,
 178                                 TASK_INTERRUPTIBLE);
 179                 if (journal->j_commit_sequence != journal->j_commit_request)
 180                         should_sleep = 0;
 181                 transaction = journal->j_running_transaction;
 182                 if (transaction && time_after_eq(jiffies,
 183                                                 transaction->t_expires))
 184                         should_sleep = 0;
 185                 if (journal->j_flags & JBD2_UNMOUNT)
 186                         should_sleep = 0;
 187                 if (should_sleep) {
 188                         spin_unlock(&journal->j_state_lock);
 189                         schedule();
 190                         spin_lock(&journal->j_state_lock);
 191                 }
 192                 finish_wait(&journal->j_wait_commit, &wait);
 193         }
 194
 195         jbd_debug(1, "kjournald2 wakes\n");
 196
 197         /*
 198          * Were we woken up by a commit wakeup event?
 199          */
 200         transaction = journal->j_running_transaction;
 201         if (transaction && time_after_eq(jiffies, transaction->t_expires)) {
 202                 journal->j_commit_request = transaction->t_tid;
 203                 jbd_debug(1, "woke because of timeout\n");
 204         }
 205         goto loop;
 206
 207 end_loop:
 208         spin_unlock(&journal->j_state_lock);
 209         del_timer_sync(&journal->j_commit_timer);
 210         journal->j_task = NULL;
 211         wake_up(&journal->j_wait_done_commit);
 212         jbd_debug(1, "Journal thread exiting.\n");
 213         return 0;
 214 }
 215
 216 static int jbd2_journal_start_thread(journal_t *journal)
 217 {
 218         struct task_struct *t;
 219
 220         t = kthread_run(kjournald2, journal, "kjournald2");
 221         if (IS_ERR(t))
 222                 return PTR_ERR(t);
 223
 224         wait_event(journal->j_wait_done_commit, journal->j_task != NULL);
 225         return 0;
 226 }
 227
 228 static void journal_kill_thread(journal_t *journal)
 229 {
 230         spin_lock(&journal->j_state_lock);
 231         journal->j_flags |= JBD2_UNMOUNT;
 232
 233         while (journal->j_task) {
 234                 wake_up(&journal->j_wait_commit);
 235                 spin_unlock(&journal->j_state_lock);
 236                 wait_event(journal->j_wait_done_commit, journal->j_task == NULL);
 237                 spin_lock(&journal->j_state_lock);
 238         }
 239         spin_unlock(&journal->j_state_lock);
 240 }
 241
 242 /*
 243  * jbd2_journal_write_metadata_buffer: write a metadata buffer to the journal.
 244  *
 245  * Writes a metadata buffer to a given disk block.  The actual IO is not
 246  * performed but a new buffer_head is constructed which labels the data
 247  * to be written with the correct destination disk block.
 248  *
 249  * Any magic-number escaping which needs to be done will cause a
 250  * copy-out here.  If the buffer happens to start with the
 251  * JBD2_MAGIC_NUMBER, then we can't write it to the log directly: the
 252  * magic number is only written to the log for descripter blocks.  In
 253  * this case, we copy the data and replace the first word with 0, and we
 254  * return a result code which indicates that this buffer needs to be
 255  * marked as an escaped buffer in the corresponding log descriptor
 256  * block.  The missing word can then be restored when the block is read
 257  * during recovery.
 258  *
 259  * If the source buffer has already been modified by a new transaction
 260  * since we took the last commit snapshot, we use the frozen copy of
 261  * that data for IO.  If we end up using the existing buffer_head's data
 262  * for the write, then we *have* to lock the buffer to prevent anyone
 263  * else from using and possibly modifying it while the IO is in
 264  * progress.
 265  *
 266  * The function returns a pointer to the buffer_heads to be used for IO.
 267  *
 268  * We assume that the journal has already been locked in this function.
 269  *
 270  * Return value:
 271  *  <0: Error
 272  * >=0: Finished OK
 273  *
 274  * On success:
 275  * Bit 0 set == escape performed on the data
 276  * Bit 1 set == buffer copy-out performed (kfree the data after IO)
 277  */
 278
 279 int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 280                                   struct journal_head  *jh_in,
 281                                   struct journal_head **jh_out,
 282                                   unsigned long long blocknr)
 283 {
 284         int need_copy_out = 0;
 285         int done_copy_out = 0;
 286         int do_escape = 0;
 287         char *mapped_data;
 288         struct buffer_head *new_bh;
 289         struct journal_head *new_jh;
 290         struct page *new_page;
 291         unsigned int new_offset;
 292         struct buffer_head *bh_in = jh2bh(jh_in);
 293
 294         /*
 295          * The buffer really shouldn't be locked: only the current committing
 296          * transaction is allowed to write it, so nobody else is allowed
 297          * to do any IO.
 298          *
 299          * akpm: except if we're journalling data, and write() output is
 300          * also part of a shared mapping, and another thread has
 301          * decided to launch a writepage() against this buffer.
 302          */
 303         J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
 304
 305         new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
 306
 307         /*
 308          * If a new transaction has already done a buffer copy-out, then
 309          * we use that version of the data for the commit.
 310          */
 311         jbd_lock_bh_state(bh_in);
 312 repeat:
 313         if (jh_in->b_frozen_data) {
 314                 done_copy_out = 1;
 315                 new_page = virt_to_page(jh_in->b_frozen_data);
 316                 new_offset = offset_in_page(jh_in->b_frozen_data);
 317         } else {
 318                 new_page = jh2bh(jh_in)->b_page;
 319                 new_offset = offset_in_page(jh2bh(jh_in)->b_data);
 320         }
 321
 322         mapped_data = kmap_atomic(new_page, KM_USER0);
 323         /*
 324          * Check for escaping
 325          */
 326         if (*((__be32 *)(mapped_data + new_offset)) ==
 327                                 cpu_to_be32(JBD2_MAGIC_NUMBER)) {
 328                 need_copy_out = 1;
 329                 do_escape = 1;
 330         }
 331         kunmap_atomic(mapped_data, KM_USER0);
 332
 333         /*
 334          * Do we need to do a data copy?
 335          */
 336         if (need_copy_out && !done_copy_out) {
 337                 char *tmp;
 338
 339                 jbd_unlock_bh_state(bh_in);
 340                 tmp = jbd2_alloc(bh_in->b_size, GFP_NOFS);
 341                 jbd_lock_bh_state(bh_in);
 342                 if (jh_in->b_frozen_data) {
 343                         jbd2_free(tmp, bh_in->b_size);
 344                         goto repeat;
 345                 }
 346
 347                 jh_in->b_frozen_data = tmp;
 348                 mapped_data = kmap_atomic(new_page, KM_USER0);
 349                 memcpy(tmp, mapped_data + new_offset, jh2bh(jh_in)->b_size);
 350                 kunmap_atomic(mapped_data, KM_USER0);
 351
 352                 new_page = virt_to_page(tmp);
 353                 new_offset = offset_in_page(tmp);
 354                 done_copy_out = 1;
 355         }
 356
 357         /*
 358          * Did we need to do an escaping?  Now we've done all the
 359          * copying, we can finally do so.
 360          */
 361         if (do_escape) {
 362                 mapped_data = kmap_atomic(new_page, KM_USER0);
 363                 *((unsigned int *)(mapped_data + new_offset)) = 0;
 364                 kunmap_atomic(mapped_data, KM_USER0);
 365         }
 366
 367         /* keep subsequent assertions sane */
 368         new_bh->b_state = 0;
 369         init_buffer(new_bh, NULL, NULL);
 370         atomic_set(&new_bh->b_count, 1);
 371         jbd_unlock_bh_state(bh_in);
 372
 373         new_jh = jbd2_journal_add_journal_head(new_bh); /* This sleeps */
 374
 375         set_bh_page(new_bh, new_page, new_offset);
 376         new_jh->b_transaction = NULL;
 377         new_bh->b_size = jh2bh(jh_in)->b_size;
 378         new_bh->b_bdev = transaction->t_journal->j_dev;
 379         new_bh->b_blocknr = blocknr;
 380         set_buffer_mapped(new_bh);
 381         set_buffer_dirty(new_bh);
 382
 383         *jh_out = new_jh;
 384
 385         /*
 386          * The to-be-written buffer needs to get moved to the io queue,
 387          * and the original buffer whose contents we are shadowing or
 388          * copying is moved to the transaction's shadow queue.
 389          */
 390         JBUFFER_TRACE(jh_in, "file as BJ_Shadow");
 391         jbd2_journal_file_buffer(jh_in, transaction, BJ_Shadow);
 392         JBUFFER_TRACE(new_jh, "file as BJ_IO");
 393         jbd2_journal_file_buffer(new_jh, transaction, BJ_IO);
 394
 395         return do_escape | (done_copy_out << 1);
 396 }
 397
 398 /*
 399  * Allocation code for the journal file.  Manage the space left in the
 400  * journal, so that we can begin checkpointing when appropriate.
 401  */
 402
 403 /*
 404  * __jbd2_log_space_left: Return the number of free blocks left in the journal.
 405  *
 406  * Called with the journal already locked.
 407  *
 408  * Called under j_state_lock
 409  */
 410
 411 int __jbd2_log_space_left(journal_t *journal)
 412 {
 413         int left = journal->j_free;
 414
 415         assert_spin_locked(&journal->j_state_lock);
 416
 417         /*
 418          * Be pessimistic here about the number of those free blocks which
 419          * might be required for log descriptor control blocks.
 420          */
 421
 422 #define MIN_LOG_RESERVED_BLOCKS 32 /* Allow for rounding errors */
 423
 424         left -= MIN_LOG_RESERVED_BLOCKS;
 425
 426         if (left <= 0)
 427                 return 0;
 428         left -= (left >> 3);
 429         return left;
 430 }
 431
 432 /*
 433  * Called under j_state_lock.  Returns true if a transaction was started.
 434  */
 435 int __jbd2_log_start_commit(journal_t *journal, tid_t target)
 436 {
 437         /*
 438          * Are we already doing a recent enough commit?
 439          */
 440         if (!tid_geq(journal->j_commit_request, target)) {
 441                 /*
 442                  * We want a new commit: OK, mark the request and wakup the
 443                  * commit thread.  We do _not_ do the commit ourselves.
 444                  */
 445
 446                 journal->j_commit_request = target;
 447                 jbd_debug(1, "JBD: requesting commit %d/%d\n",
 448                           journal->j_commit_request,
 449                           journal->j_commit_sequence);
 450                 wake_up(&journal->j_wait_commit);
 451                 return 1;
 452         }
 453         return 0;
 454 }
 455
 456 int jbd2_log_start_commit(journal_t *journal, tid_t tid)
 457 {
 458         int ret;
 459
 460         spin_lock(&journal->j_state_lock);
 461         ret = __jbd2_log_start_commit(journal, tid);
 462         spin_unlock(&journal->j_state_lock);
 463         return ret;
 464 }
 465
 466 /*
 467  * Force and wait upon a commit if the calling process is not within
 468  * transaction.  This is used for forcing out undo-protected data which contains
 469  * bitmaps, when the fs is running out of space.
 470  *
 471  * We can only force the running transaction if we don't have an active handle;
 472  * otherwise, we will deadlock.
 473  *
 474  * Returns true if a transaction was started.
 475  */
 476 int jbd2_journal_force_commit_nested(journal_t *journal)
 477 {
 478         transaction_t *transaction = NULL;
 479         tid_t tid;
 480
 481         spin_lock(&journal->j_state_lock);
 482         if (journal->j_running_transaction && !current->journal_info) {
 483                 transaction = journal->j_running_transaction;
 484                 __jbd2_log_start_commit(journal, transaction->t_tid);
 485         } else if (journal->j_committing_transaction)
 486                 transaction = journal->j_committing_transaction;
 487
 488         if (!transaction) {
 489                 spin_unlock(&journal->j_state_lock);
 490                 return 0;       /* Nothing to retry */
 491         }
 492
 493         tid = transaction->t_tid;
 494         spin_unlock(&journal->j_state_lock);
 495         jbd2_log_wait_commit(journal, tid);
 496         return 1;
 497 }
 498
 499 /*
 500  * Start a commit of the current running transaction (if any).  Returns true
 501  * if a transaction was started, and fills its tid in at *ptid
 502  */
 503 int jbd2_journal_start_commit(journal_t *journal, tid_t *ptid)
 504 {
 505         int ret = 0;
 506
 507         spin_lock(&journal->j_state_lock);
 508         if (journal->j_running_transaction) {
 509                 tid_t tid = journal->j_running_transaction->t_tid;
 510
 511                 ret = __jbd2_log_start_commit(journal, tid);
 512                 if (ret && ptid)
 513                         *ptid = tid;
 514         } else if (journal->j_committing_transaction && ptid) {
 515                 /*
 516                  * If ext3_write_super() recently started a commit, then we
 517                  * have to wait for completion of that transaction
 518                  */
 519                 *ptid = journal->j_committing_transaction->t_tid;
 520                 ret = 1;
 521         }
 522         spin_unlock(&journal->j_state_lock);
 523         return ret;
 524 }
 525
 526 /*
 527  * Wait for a specified commit to complete.
 528  * The caller may not hold the journal lock.
 529  */
 530 int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
 531 {
 532         int err = 0;
 533
 534 #ifdef CONFIG_JBD2_DEBUG
 535         spin_lock(&journal->j_state_lock);
 536         if (!tid_geq(journal->j_commit_request, tid)) {
 537                 printk(KERN_EMERG
 538                        "%s: error: j_commit_request=%d, tid=%d\n",
 539                        __func__, journal->j_commit_request, tid);
 540         }
 541         spin_unlock(&journal->j_state_lock);
 542 #endif
 543         spin_lock(&journal->j_state_lock);
 544         while (tid_gt(tid, journal->j_commit_sequence)) {
 545                 jbd_debug(1, "JBD: want %d, j_commit_sequence=%d\n",
 546                                   tid, journal->j_commit_sequence);
 547                 wake_up(&journal->j_wait_commit);
 548                 spin_unlock(&journal->j_state_lock);
 549                 wait_event(journal->j_wait_done_commit,
 550                                 !tid_gt(tid, journal->j_commit_sequence));
 551                 spin_lock(&journal->j_state_lock);
 552         }
 553         spin_unlock(&journal->j_state_lock);
 554
 555         if (unlikely(is_journal_aborted(journal))) {
 556                 printk(KERN_EMERG "journal commit I/O error\n");
 557                 err = -EIO;
 558         }
 559         return err;
 560 }
 561
 562 /*
 563  * Log buffer allocation routines:
 564  */
 565
 566 int jbd2_journal_next_log_block(journal_t *journal, unsigned long long *retp)
 567 {
 568         unsigned long blocknr;
 569
 570         spin_lock(&journal->j_state_lock);
 571         J_ASSERT(journal->j_free > 1);
 572
 573         blocknr = journal->j_head;
 574         journal->j_head++;
 575         journal->j_free--;
 576         if (journal->j_head == journal->j_last)
 577                 journal->j_head = journal->j_first;
 578         spin_unlock(&journal->j_state_lock);
 579         return jbd2_journal_bmap(journal, blocknr, retp);
 580 }
 581
 582 /*
 583  * Conversion of logical to physical block numbers for the journal
 584  *
 585  * On external journals the journal blocks are identity-mapped, so
 586  * this is a no-op.  If needed, we can use j_blk_offset - everything is
 587  * ready.
 588  */
 589 int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
 590                  unsigned long long *retp)
 591 {
 592         int err = 0;
 593         unsigned long long ret;
 594
 595         if (journal->j_inode) {
 596                 ret = bmap(journal->j_inode, blocknr);
 597                 if (ret)
 598                         *retp = ret;
 599                 else {
 600                         printk(KERN_ALERT "%s: journal block not found "
 601                                         "at offset %lu on %s\n",
 602                                __func__, blocknr, journal->j_devname);
 603                         err = -EIO;
 604                         __journal_abort_soft(journal, err);
 605                 }
 606         } else {
 607                 *retp = blocknr; /* +journal->j_blk_offset */
 608         }
 609         return err;
 610 }
 611
 612 /*
 613  * We play buffer_head aliasing tricks to write data/metadata blocks to
 614  * the journal without copying their contents, but for journal
 615  * descriptor blocks we do need to generate bona fide buffers.
 616  *
 617  * After the caller of jbd2_journal_get_descriptor_buffer() has finished modifying
 618  * the buffer's contents they really should run flush_dcache_page(bh->b_page).
 619  * But we don't bother doing that, so there will be coherency problems with
 620  * mmaps of blockdevs which hold live JBD-controlled filesystems.
 621  */
 622 struct journal_head *jbd2_journal_get_descriptor_buffer(journal_t *journal)
 623 {
 624         struct buffer_head *bh;
 625         unsigned long long blocknr;
 626         int err;
 627
 628         err = jbd2_journal_next_log_block(journal, &blocknr);
 629
 630         if (err)
 631                 return NULL;
 632
 633         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
 634         lock_buffer(bh);
 635         memset(bh->b_data, 0, journal->j_blocksize);
 636         set_buffer_uptodate(bh);
 637         unlock_buffer(bh);
 638         BUFFER_TRACE(bh, "return this buffer");
 639         return jbd2_journal_add_journal_head(bh);
 640 }
 641
 642 struct jbd2_stats_proc_session {
 643         journal_t *journal;
 644         struct transaction_stats_s *stats;
 645         int start;
 646         int max;
 647 };
 648
 649 static void *jbd2_history_skip_empty(struct jbd2_stats_proc_session *s,
 650                                         struct transaction_stats_s *ts,
 651                                         int first)
 652 {
 653         if (ts == s->stats + s->max)
 654                 ts = s->stats;
 655         if (!first && ts == s->stats + s->start)
 656                 return NULL;
 657         while (ts->ts_type == 0) {
 658                 ts++;
 659                 if (ts == s->stats + s->max)
 660                         ts = s->stats;
 661                 if (ts == s->stats + s->start)
 662                         return NULL;
 663         }
 664         return ts;
 665
 666 }
 667
 668 static void *jbd2_seq_history_start(struct seq_file *seq, loff_t *pos)
 669 {
 670         struct jbd2_stats_proc_session *s = seq->private;
 671         struct transaction_stats_s *ts;
 672         int l = *pos;
 673
 674         if (l == 0)
 675                 return SEQ_START_TOKEN;
 676         ts = jbd2_history_skip_empty(s, s->stats + s->start, 1);
 677         if (!ts)
 678                 return NULL;
 679         l--;
 680         while (l) {
 681                 ts = jbd2_history_skip_empty(s, ++ts, 0);
 682                 if (!ts)
 683                         break;
 684                 l--;
 685         }
 686         return ts;
 687 }
 688
 689 static void *jbd2_seq_history_next(struct seq_file *seq, void *v, loff_t *pos)
 690 {
 691         struct jbd2_stats_proc_session *s = seq->private;
 692         struct transaction_stats_s *ts = v;
 693
 694         ++*pos;
 695         if (v == SEQ_START_TOKEN)
 696                 return jbd2_history_skip_empty(s, s->stats + s->start, 1);
 697         else
 698                 return jbd2_history_skip_empty(s, ++ts, 0);
 699 }
 700
 701 static int jbd2_seq_history_show(struct seq_file *seq, void *v)
 702 {
 703         struct transaction_stats_s *ts = v;
 704         if (v == SEQ_START_TOKEN) {
 705                 seq_printf(seq, "%-4s %-5s %-5s %-5s %-5s %-5s %-5s %-6s %-5s "
 706                                 "%-5s %-5s %-5s %-5s %-5s\n", "R/C", "tid",
 707                                 "wait", "run", "lock", "flush", "log", "hndls",
 708                                 "block", "inlog", "ctime", "write", "drop",
 709                                 "close");
 710                 return 0;
 711         }
 712         if (ts->ts_type == JBD2_STATS_RUN)
 713                 seq_printf(seq, "%-4s %-5lu %-5u %-5u %-5u %-5u %-5u "
 714                                 "%-6lu %-5lu %-5lu\n", "R", ts->ts_tid,
 715                                 jiffies_to_msecs(ts->u.run.rs_wait),
 716                                 jiffies_to_msecs(ts->u.run.rs_running),
 717                                 jiffies_to_msecs(ts->u.run.rs_locked),
 718                                 jiffies_to_msecs(ts->u.run.rs_flushing),
 719                                 jiffies_to_msecs(ts->u.run.rs_logging),
 720                                 ts->u.run.rs_handle_count,
 721                                 ts->u.run.rs_blocks,
 722                                 ts->u.run.rs_blocks_logged);
 723         else if (ts->ts_type == JBD2_STATS_CHECKPOINT)
 724                 seq_printf(seq, "%-4s %-5lu %48s %-5u %-5lu %-5lu %-5lu\n",
 725                                 "C", ts->ts_tid, " ",
 726                                 jiffies_to_msecs(ts->u.chp.cs_chp_time),
 727                                 ts->u.chp.cs_written, ts->u.chp.cs_dropped,
 728                                 ts->u.chp.cs_forced_to_close);
 729         else
 730                 J_ASSERT(0);
 731         return 0;
 732 }
 733
 734 static void jbd2_seq_history_stop(struct seq_file *seq, void *v)
 735 {
 736 }
 737
 738 static struct seq_operations jbd2_seq_history_ops = {
 739         .start  = jbd2_seq_history_start,
 740         .next   = jbd2_seq_history_next,
 741         .stop   = jbd2_seq_history_stop,
 742         .show   = jbd2_seq_history_show,
 743 };
 744
 745 static int jbd2_seq_history_open(struct inode *inode, struct file *file)
 746 {
 747         journal_t *journal = PDE(inode)->data;
 748         struct jbd2_stats_proc_session *s;
 749         int rc, size;
 750
 751         s = kmalloc(sizeof(*s), GFP_KERNEL);
 752         if (s == NULL)
 753                 return -ENOMEM;
 754         size = sizeof(struct transaction_stats_s) * journal->j_history_max;
 755         s->stats = kmalloc(size, GFP_KERNEL);
 756         if (s->stats == NULL) {
 757                 kfree(s);
 758                 return -ENOMEM;
 759         }
 760         spin_lock(&journal->j_history_lock);
 761         memcpy(s->stats, journal->j_history, size);
 762         s->max = journal->j_history_max;
 763         s->start = journal->j_history_cur % s->max;
 764         spin_unlock(&journal->j_history_lock);
 765
 766         rc = seq_open(file, &jbd2_seq_history_ops);
 767         if (rc == 0) {
 768                 struct seq_file *m = file->private_data;
 769                 m->private = s;
 770         } else {
 771                 kfree(s->stats);
 772                 kfree(s);
 773         }
 774         return rc;
 775
 776 }
 777
 778 static int jbd2_seq_history_release(struct inode *inode, struct file *file)
 779 {
 780         struct seq_file *seq = file->private_data;
 781         struct jbd2_stats_proc_session *s = seq->private;
 782
 783         kfree(s->stats);
 784         kfree(s);
 785         return seq_release(inode, file);
 786 }
 787
 788 static struct file_operations jbd2_seq_history_fops = {
 789         .owner          = THIS_MODULE,
 790         .open           = jbd2_seq_history_open,
 791         .read           = seq_read,
 792         .llseek         = seq_lseek,
 793         .release        = jbd2_seq_history_release,
 794 };
 795
 796 static void *jbd2_seq_info_start(struct seq_file *seq, loff_t *pos)
 797 {
 798         return *pos ? NULL : SEQ_START_TOKEN;
 799 }
 800
 801 static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
 802 {
 803         return NULL;
 804 }
 805
 806 static int jbd2_seq_info_show(struct seq_file *seq, void *v)
 807 {
 808         struct jbd2_stats_proc_session *s = seq->private;
 809
 810         if (v != SEQ_START_TOKEN)
 811                 return 0;
 812         seq_printf(seq, "%lu transaction, each upto %u blocks\n",
 813                         s->stats->ts_tid,
 814                         s->journal->j_max_transaction_buffers);
 815         if (s->stats->ts_tid == 0)
 816                 return 0;
 817         seq_printf(seq, "average: \n  %ums waiting for transaction\n",
 818             jiffies_to_msecs(s->stats->u.run.rs_wait / s->stats->ts_tid));
 819         seq_printf(seq, "  %ums running transaction\n",
 820             jiffies_to_msecs(s->stats->u.run.rs_running / s->stats->ts_tid));
 821         seq_printf(seq, "  %ums transaction was being locked\n",
 822             jiffies_to_msecs(s->stats->u.run.rs_locked / s->stats->ts_tid));
 823         seq_printf(seq, "  %ums flushing data (in ordered mode)\n",
 824             jiffies_to_msecs(s->stats->u.run.rs_flushing / s->stats->ts_tid));
 825         seq_printf(seq, "  %ums logging transaction\n",
 826             jiffies_to_msecs(s->stats->u.run.rs_logging / s->stats->ts_tid));
 827         seq_printf(seq, "  %lu handles per transaction\n",
 828             s->stats->u.run.rs_handle_count / s->stats->ts_tid);
 829         seq_printf(seq, "  %lu blocks per transaction\n",
 830             s->stats->u.run.rs_blocks / s->stats->ts_tid);
 831         seq_printf(seq, "  %lu logged blocks per transaction\n",
 832             s->stats->u.run.rs_blocks_logged / s->stats->ts_tid);
 833         return 0;
 834 }
 835
 836 static void jbd2_seq_info_stop(struct seq_file *seq, void *v)
 837 {
 838 }
 839
 840 static struct seq_operations jbd2_seq_info_ops = {
 841         .start  = jbd2_seq_info_start,
 842         .next   = jbd2_seq_info_next,
 843         .stop   = jbd2_seq_info_stop,
 844         .show   = jbd2_seq_info_show,
 845 };
 846
 847 static int jbd2_seq_info_open(struct inode *inode, struct file *file)
 848 {
 849         journal_t *journal = PDE(inode)->data;
 850         struct jbd2_stats_proc_session *s;
 851         int rc, size;
 852
 853         s = kmalloc(sizeof(*s), GFP_KERNEL);
 854         if (s == NULL)
 855                 return -ENOMEM;
 856         size = sizeof(struct transaction_stats_s);
 857         s->stats = kmalloc(size, GFP_KERNEL);
 858         if (s->stats == NULL) {
 859                 kfree(s);
 860                 return -ENOMEM;
 861         }
 862         spin_lock(&journal->j_history_lock);
 863         memcpy(s->stats, &journal->j_stats, size);
 864         s->journal = journal;
 865         spin_unlock(&journal->j_history_lock);
 866
 867         rc = seq_open(file, &jbd2_seq_info_ops);
 868         if (rc == 0) {
 869                 struct seq_file *m = file->private_data;
 870                 m->private = s;
 871         } else {
 872                 kfree(s->stats);
 873                 kfree(s);
 874         }
 875         return rc;
 876
 877 }
 878
 879 static int jbd2_seq_info_release(struct inode *inode, struct file *file)
 880 {
 881         struct seq_file *seq = file->private_data;
 882         struct jbd2_stats_proc_session *s = seq->private;
 883         kfree(s->stats);
 884         kfree(s);
 885         return seq_release(inode, file);
 886 }
 887
 888 static struct file_operations jbd2_seq_info_fops = {
 889         .owner          = THIS_MODULE,
 890         .open           = jbd2_seq_info_open,
 891         .read           = seq_read,
 892         .llseek         = seq_lseek,
 893         .release        = jbd2_seq_info_release,
 894 };
 895
 896 static struct proc_dir_entry *proc_jbd2_stats;
 897
 898 static void jbd2_stats_proc_init(journal_t *journal)
 899 {
 900         journal->j_proc_entry = proc_mkdir(journal->j_devname, proc_jbd2_stats);
 901         if (journal->j_proc_entry) {
 902                 proc_create_data("history", S_IRUGO, journal->j_proc_entry,
 903                                  &jbd2_seq_history_fops, journal);
 904                 proc_create_data("info", S_IRUGO, journal->j_proc_entry,
 905                                  &jbd2_seq_info_fops, journal);
 906         }
 907 }
 908
 909 static void jbd2_stats_proc_exit(journal_t *journal)
 910 {
 911         remove_proc_entry("info", journal->j_proc_entry);
 912         remove_proc_entry("history", journal->j_proc_entry);
 913         remove_proc_entry(journal->j_devname, proc_jbd2_stats);
 914 }
 915
 916 static void journal_init_stats(journal_t *journal)
 917 {
 918         int size;
 919
 920         if (!proc_jbd2_stats)
 921                 return;
 922
 923         journal->j_history_max = 100;
 924         size = sizeof(struct transaction_stats_s) * journal->j_history_max;
 925         journal->j_history = kzalloc(size, GFP_KERNEL);
 926         if (!journal->j_history) {
 927                 journal->j_history_max = 0;
 928                 return;
 929         }
 930         spin_lock_init(&journal->j_history_lock);
 931 }
 932
 933 /*
 934  * Management for journal control blocks: functions to create and
 935  * destroy journal_t structures, and to initialise and read existing
 936  * journal blocks from disk.  */
 937
 938 /* First: create and setup a journal_t object in memory.  We initialise
 939  * very few fields yet: that has to wait until we have created the
 940  * journal structures from from scratch, or loaded them from disk. */
 941
 942 static journal_t * journal_init_common (void)
 943 {
 944         journal_t *journal;
 945         int err;
 946
 947         journal = kzalloc(sizeof(*journal), GFP_KERNEL|__GFP_NOFAIL);
 948         if (!journal)
 949                 goto fail;
 950
 951         init_waitqueue_head(&journal->j_wait_transaction_locked);
 952         init_waitqueue_head(&journal->j_wait_logspace);
 953         init_waitqueue_head(&journal->j_wait_done_commit);
 954         init_waitqueue_head(&journal->j_wait_checkpoint);
 955         init_waitqueue_head(&journal->j_wait_commit);
 956         init_waitqueue_head(&journal->j_wait_updates);
 957         mutex_init(&journal->j_barrier);
 958         mutex_init(&journal->j_checkpoint_mutex);
 959         spin_lock_init(&journal->j_revoke_lock);
 960         spin_lock_init(&journal->j_list_lock);
 961         spin_lock_init(&journal->j_state_lock);
 962
 963         journal->j_commit_interval = (HZ * JBD2_DEFAULT_MAX_COMMIT_AGE);
 964
 965         /* The journal is marked for error until we succeed with recovery! */
 966         journal->j_flags = JBD2_ABORT;
 967
 968         /* Set up a default-sized revoke table for the new mount. */
 969         err = jbd2_journal_init_revoke(journal, JOURNAL_REVOKE_DEFAULT_HASH);
 970         if (err) {
 971                 kfree(journal);
 972                 goto fail;
 973         }
 974
 975         journal_init_stats(journal);
 976
 977         return journal;
 978 fail:
 979         return NULL;
 980 }
 981
 982 /* jbd2_journal_init_dev and jbd2_journal_init_inode:
 983  *
 984  * Create a journal structure assigned some fixed set of disk blocks to
 985  * the journal.  We don't actually touch those disk blocks yet, but we
 986  * need to set up all of the mapping information to tell the journaling
 987  * system where the journal blocks are.
 988  *
 989  */
 990
 991 /**
 992  *  journal_t * jbd2_journal_init_dev() - creates and initialises a journal structure
 993  *  @bdev: Block device on which to create the journal
 994  *  @fs_dev: Device which hold journalled filesystem for this journal.
 995  *  @start: Block nr Start of journal.
 996  *  @len:  Length of the journal in blocks.
 997  *  @blocksize: blocksize of journalling device
 998  *
 999  *  Returns: a newly created journal_t *
1000  *
1001  *  jbd2_journal_init_dev creates a journal which maps a fixed contiguous
1002  *  range of blocks on an arbitrary block device.
1003  *
1004  */
1005 journal_t * jbd2_journal_init_dev(struct block_device *bdev,
1006                         struct block_device *fs_dev,
1007                         unsigned long long start, int len, int blocksize)
1008 {
1009         journal_t *journal = journal_init_common();
1010         struct buffer_head *bh;
1011         char *p;
1012         int n;
1013
1014         if (!journal)
1015                 return NULL;
1016
1017         /* journal descriptor can store up to n blocks -bzzz */
1018         journal->j_blocksize = blocksize;
1019         n = journal->j_blocksize / sizeof(journal_block_tag_t);
1020         journal->j_wbufsize = n;
1021         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
1022         if (!journal->j_wbuf) {
1023                 printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
1024                         __func__);
1025                 kfree(journal);
1026                 journal = NULL;
1027                 goto out;
1028         }
1029         journal->j_dev = bdev;
1030         journal->j_fs_dev = fs_dev;
1031         journal->j_blk_offset = start;
1032         journal->j_maxlen = len;
1033         bdevname(journal->j_dev, journal->j_devname);
1034         p = journal->j_devname;
1035         while ((p = strchr(p, '/')))
1036                 *p = '!';
1037         jbd2_stats_proc_init(journal);
1038
1039         bh = __getblk(journal->j_dev, start, journal->j_blocksize);
1040         J_ASSERT(bh != NULL);
1041         journal->j_sb_buffer = bh;
1042         journal->j_superblock = (journal_superblock_t *)bh->b_data;
1043 out:
1044         return journal;
1045 }
1046
1047 /**
1048  *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
1049  *  @inode: An inode to create the journal in
1050  *
1051  * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
1052  * the journal.  The inode must exist already, must support bmap() and
1053  * must have all data blocks preallocated.
1054  */
1055 journal_t * jbd2_journal_init_inode (struct inode *inode)
1056 {
1057         struct buffer_head *bh;
1058         journal_t *journal = journal_init_common();
1059         char *p;
1060         int err;
1061         int n;
1062         unsigned long long blocknr;
1063
1064         if (!journal)
1065                 return NULL;
1066
1067         journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
1068         journal->j_inode = inode;
1069         bdevname(journal->j_dev, journal->j_devname);
1070         p = journal->j_devname;
1071         while ((p = strchr(p, '/')))
1072                 *p = '!';
1073         p = journal->j_devname + strlen(journal->j_devname);
1074         sprintf(p, ":%lu", journal->j_inode->i_ino);
1075         jbd_debug(1,
1076                   "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
1077                   journal, inode->i_sb->s_id, inode->i_ino,
1078                   (long long) inode->i_size,
1079                   inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
1080
1081         journal->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
1082         journal->j_blocksize = inode->i_sb->s_blocksize;
1083         jbd2_stats_proc_init(journal);
1084
1085         /* journal descriptor can store up to n blocks -bzzz */
1086         n = journal->j_blocksize / sizeof(journal_block_tag_t);
1087         journal->j_wbufsize = n;
1088         journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
1089         if (!journal->j_wbuf) {
1090                 printk(KERN_ERR "%s: Cant allocate bhs for commit thread\n",
1091                         __func__);
1092                 kfree(journal);
1093                 return NULL;
1094         }
1095
1096         err = jbd2_journal_bmap(journal, 0, &blocknr);
1097         /* If that failed, give up */
1098         if (err) {
1099                 printk(KERN_ERR "%s: Cannnot locate journal superblock\n",
1100                        __func__);
1101                 kfree(journal);
1102                 return NULL;
1103         }
1104
1105         bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
1106         J_ASSERT(bh != NULL);
1107         journal->j_sb_buffer = bh;
1108         journal->j_superblock = (journal_superblock_t *)bh->b_data;
1109
1110         return journal;
1111 }
1112
1113 /*
1114  * If the journal init or create aborts, we need to mark the journal
1115  * superblock as being NULL to prevent the journal destroy from writing
1116  * back a bogus superblock.
1117  */
1118 static void journal_fail_superblock (journal_t *journal)
1119 {
1120         struct buffer_head *bh = journal->j_sb_buffer;
1121         brelse(bh);
1122         journal->j_sb_buffer = NULL;
1123 }
1124
1125 /*
1126  * Given a journal_t structure, initialise the various fields for
1127  * startup of a new journaling session.  We use this both when creating
1128  * a journal, and after recovering an old journal to reset it for
1129  * subsequent use.
1130  */
1131
1132 static int journal_reset(journal_t *journal)
1133 {
1134         journal_superblock_t *sb = journal->j_superblock;
1135         unsigned long long first, last;
1136
1137         first = be32_to_cpu(sb->s_first);
1138         last = be32_to_cpu(sb->s_maxlen);
1139
1140         journal->j_first = first;
1141         journal->j_last = last;
1142
1143         journal->j_head = first;
1144         journal->j_tail = first;
1145         journal->j_free = last - first;
1146
1147         journal->j_tail_sequence = journal->j_transaction_sequence;
1148         journal->j_commit_sequence = journal->j_transaction_sequence - 1;
1149         journal->j_commit_request = journal->j_commit_sequence;
1150
1151         journal->j_max_transaction_buffers = journal->j_maxlen / 4;
1152
1153         /* Add the dynamic fields and write it to disk. */
1154         jbd2_journal_update_superblock(journal, 1);
1155         return jbd2_journal_start_thread(journal);
1156 }
1157
1158 /**
1159  * int jbd2_journal_create() - Initialise the new journal file
1160  * @journal: Journal to create. This structure must have been initialised
1161  *
1162  * Given a journal_t structure which tells us which disk blocks we can
1163  * use, create a new journal superblock and initialise all of the
1164  * journal fields from scratch.
1165  **/
1166 int jbd2_journal_create(journal_t *journal)
1167 {
1168         unsigned long long blocknr;
1169         struct buffer_head *bh;
1170         journal_superblock_t *sb;
1171         int i, err;
1172
1173         if (journal->j_maxlen < JBD2_MIN_JOURNAL_BLOCKS) {
1174                 printk (KERN_ERR "Journal length (%d blocks) too short.\n",
1175                         journal->j_maxlen);
1176                 journal_fail_superblock(journal);
1177                 return -EINVAL;
1178         }
1179
1180         if (journal->j_inode == NULL) {
1181                 /*
1182                  * We don't know what block to start at!
1183                  */
1184                 printk(KERN_EMERG
1185                        "%s: creation of journal on external device!\n",
1186                        __func__);
1187                 BUG();
1188         }
1189
1190         /* Zero out the entire journal on disk.  We cannot afford to
1191            have any blocks on disk beginning with JBD2_MAGIC_NUMBER. */
1192         jbd_debug(1, "JBD: Zeroing out journal blocks...\n");
1193         for (i = 0; i < journal->j_maxlen; i++) {
1194                 err = jbd2_journal_bmap(journal, i, &blocknr);
1195                 if (err)
1196                         return err;
1197                 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
1198                 lock_buffer(bh);
1199                 memset (bh->b_data, 0, journal->j_blocksize);
1200                 BUFFER_TRACE(bh, "marking dirty");
1201                 mark_buffer_dirty(bh);
1202                 BUFFER_TRACE(bh, "marking uptodate");
1203                 set_buffer_uptodate(bh);
1204                 unlock_buffer(bh);
1205                 __brelse(bh);
1206         }
1207
1208         sync_blockdev(journal->j_dev);
1209         jbd_debug(1, "JBD: journal cleared.\n");
1210
1211         /* OK, fill in the initial static fields in the new superblock */
1212         sb = journal->j_superblock;
1213
1214         sb->s_header.h_magic     = cpu_to_be32(JBD2_MAGIC_NUMBER);
1215         sb->s_header.h_blocktype = cpu_to_be32(JBD2_SUPERBLOCK_V2);
1216
1217         sb->s_blocksize = cpu_to_be32(journal->j_blocksize);
1218         sb->s_maxlen    = cpu_to_be32(journal->j_maxlen);
1219         sb->s_first     = cpu_to_be32(1);
1220
1221         journal->j_transaction_sequence = 1;
1222
1223         journal->j_flags &= ~JBD2_ABORT;
1224         journal->j_format_version = 2;
1225
1226         return journal_reset(journal);
1227 }
1228
1229 /**
1230  * void jbd2_journal_update_superblock() - Update journal sb on disk.
1231  * @journal: The journal to update.
1232  * @wait: Set to '0' if you don't want to wait for IO completion.
1233  *
1234  * Update a journal's dynamic superblock fields and write it to disk,
1235  * optionally waiting for the IO to complete.
1236  */
1237 void jbd2_journal_update_superblock(journal_t *journal, int wait)
1238 {
1239         journal_superblock_t *sb = journal->j_superblock;
1240         struct buffer_head *bh = journal->j_sb_buffer;
1241
1242         /*
1243          * As a special case, if the on-disk copy is already marked as needing
1244          * no recovery (s_start == 0) and there are no outstanding transactions
1245          * in the filesystem, then we can safely defer the superblock update
1246          * until the next commit by setting JBD2_FLUSHED.  This avoids
1247          * attempting a write to a potential-readonly device.
1248          */
1249         if (sb->s_start == 0 && journal->j_tail_sequence ==
1250                                 journal->j_transaction_sequence) {
1251                 jbd_debug(1,"JBD: Skipping superblock update on recovered sb "
1252                         "(start %ld, seq %d, errno %d)\n",
1253                         journal->j_tail, journal->j_tail_sequence,
1254                         journal->j_errno);
1255                 goto out;
1256         }
1257
1258         if (buffer_write_io_error(bh)) {
1259                 /*
1260                  * Oh, dear.  A previous attempt to write the journal
1261                  * superblock failed.  This could happen because the
1262                  * USB device was yanked out.  Or it could happen to
1263                  * be a transient write error and maybe the block will
1264                  * be remapped.  Nothing we can do but to retry the
1265                  * write and hope for the best.
1266                  */
1267                 printk(KERN_ERR "JBD2: previous I/O error detected "
1268                        "for journal superblock update for %s.\n",
1269                        journal->j_devname);
1270                 clear_buffer_write_io_error(bh);
1271                 set_buffer_uptodate(bh);
1272         }
1273
1274         spin_lock(&journal->j_state_lock);
1275         jbd_debug(1,"JBD: updating superblock (start %ld, seq %d, errno %d)\n",
1276                   journal->j_tail, journal->j_tail_sequence, journal->j_errno);
1277
1278         sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
1279         sb->s_start    = cpu_to_be32(journal->j_tail);
1280         sb->s_errno    = cpu_to_be32(journal->j_errno);
1281         spin_unlock(&journal->j_state_lock);
1282
1283         BUFFER_TRACE(bh, "marking dirty");
1284         mark_buffer_dirty(bh);
1285         if (wait) {
1286                 sync_dirty_buffer(bh);
1287                 if (buffer_write_io_error(bh)) {
1288                         printk(KERN_ERR "JBD2: I/O error detected "
1289                                "when updating journal superblock for %s.\n",
1290                                journal->j_devname);
1291                         clear_buffer_write_io_error(bh);
1292                         set_buffer_uptodate(bh);
1293                 }
1294         } else
1295                 ll_rw_block(SWRITE, 1, &bh);
1296
1297 out:
1298         /* If we have just flushed the log (by marking s_start==0), then
1299          * any future commit will have to be careful to update the
1300          * superblock again to re-record the true start of the log. */
1301
1302         spin_lock(&journal->j_state_lock);
1303         if (sb->s_start)
1304                 journal->j_flags &= ~JBD2_FLUSHED;
1305         else
1306                 journal->j_flags |= JBD2_FLUSHED;
1307         spin_unlock(&journal->j_state_lock);
1308 }
1309
1310 /*
1311  * Read the superblock for a given journal, performing initial
1312  * validation of the format.
1313  */
1314
1315 static int journal_get_superblock(journal_t *journal)
1316 {
1317         struct buffer_head *bh;
1318         journal_superblock_t *sb;
1319         int err = -EIO;
1320
1321         bh = journal->j_sb_buffer;
1322
1323         J_ASSERT(bh != NULL);
1324         if (!buffer_uptodate(bh)) {
1325                 ll_rw_block(READ, 1, &bh);
1326                 wait_on_buffer(bh);
1327                 if (!buffer_uptodate(bh)) {
1328                         printk (KERN_ERR
1329                                 "JBD: IO error reading journal superblock\n");
1330                         goto out;
1331                 }
1332         }
1333
1334         sb = journal->j_superblock;
1335
1336         err = -EINVAL;
1337
1338         if (sb->s_header.h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER) ||
1339             sb->s_blocksize != cpu_to_be32(journal->j_blocksize)) {
1340                 printk(KERN_WARNING "JBD: no valid journal superblock found\n");
1341                 goto out;
1342         }
1343
1344         switch(be32_to_cpu(sb->s_header.h_blocktype)) {
1345         case JBD2_SUPERBLOCK_V1:
1346                 journal->j_format_version = 1;
1347                 break;
1348         case JBD2_SUPERBLOCK_V2:
1349                 journal->j_format_version = 2;
1350                 break;
1351         default:
1352                 printk(KERN_WARNING "JBD: unrecognised superblock format ID\n");
1353                 goto out;
1354         }
1355
1356         if (be32_to_cpu(sb->s_maxlen) < journal->j_maxlen)
1357                 journal->j_maxlen = be32_to_cpu(sb->s_maxlen);
1358         else if (be32_to_cpu(sb->s_maxlen) > journal->j_maxlen) {
1359                 printk (KERN_WARNING "JBD: journal file too short\n");
1360                 goto out;
1361         }
1362
1363         return 0;
1364
1365 out:
1366         journal_fail_superblock(journal);
1367         return err;
1368 }
1369
1370 /*
1371  * Load the on-disk journal superblock and read the key fields into the
1372  * journal_t.
1373  */
1374
1375 static int load_superblock(journal_t *journal)
1376 {
1377         int err;
1378         journal_superblock_t *sb;
1379
1380         err = journal_get_superblock(journal);
1381         if (err)
1382                 return err;
1383
1384         sb = journal->j_superblock;
1385
1386         journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
1387         journal->j_tail = be32_to_cpu(sb->s_start);
1388         journal->j_first = be32_to_cpu(sb->s_first);
1389         journal->j_last = be32_to_cpu(sb->s_maxlen);
1390         journal->j_errno = be32_to_cpu(sb->s_errno);
1391
1392         return 0;
1393 }
1394
1395
1396 /**
1397  * int jbd2_journal_load() - Read journal from disk.
1398  * @journal: Journal to act on.
1399  *
1400  * Given a journal_t structure which tells us which disk blocks contain
1401  * a journal, read the journal from disk to initialise the in-memory
1402  * structures.
1403  */
1404 int jbd2_journal_load(journal_t *journal)
1405 {
1406         int err;
1407         journal_superblock_t *sb;
1408
1409         err = load_superblock(journal);
1410         if (err)
1411                 return err;
1412
1413         sb = journal->j_superblock;
1414         /* If this is a V2 superblock, then we have to check the
1415          * features flags on it. */
1416
1417         if (journal->j_format_version >= 2) {
1418                 if ((sb->s_feature_ro_compat &
1419                      ~cpu_to_be32(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
1420                     (sb->s_feature_incompat &
1421                      ~cpu_to_be32(JBD2_KNOWN_INCOMPAT_FEATURES))) {
1422                         printk (KERN_WARNING
1423                                 "JBD: Unrecognised features on journal\n");
1424                         return -EINVAL;
1425                 }
1426         }
1427
1428         /* Let the recovery code check whether it needs to recover any
1429          * data from the journal. */
1430         if (jbd2_journal_recover(journal))
1431                 goto recovery_error;
1432
1433         /* OK, we've finished with the dynamic journal bits:
1434          * reinitialise the dynamic contents of the superblock in memory
1435          * and reset them on disk. */
1436         if (journal_reset(journal))
1437                 goto recovery_error;
1438
1439         journal->j_flags &= ~JBD2_ABORT;
1440         journal->j_flags |= JBD2_LOADED;
1441         return 0;
1442
1443 recovery_error:
1444         printk (KERN_WARNING "JBD: recovery failed\n");
1445         return -EIO;
1446 }
1447
1448 /**
1449  * void jbd2_journal_destroy() - Release a journal_t structure.
1450  * @journal: Journal to act on.
1451  *
1452  * Release a journal_t structure once it is no longer in use by the
1453  * journaled object.
1454  */
1455 void jbd2_journal_destroy(journal_t *journal)
1456 {
1457         /* Wait for the commit thread to wake up and die. */
1458         journal_kill_thread(journal);
1459
1460         /* Force a final log commit */
1461         if (journal->j_running_transaction)
1462                 jbd2_journal_commit_transaction(journal);
1463
1464         /* Force any old transactions to disk */
1465
1466         /* Totally anal locking here... */
1467         spin_lock(&journal->j_list_lock);
1468         while (journal->j_checkpoint_transactions != NULL) {
1469                 spin_unlock(&journal->j_list_lock);
1470                 jbd2_log_do_checkpoint(journal);
1471                 spin_lock(&journal->j_list_lock);
1472         }
1473
1474         J_ASSERT(journal->j_running_transaction == NULL);
1475         J_ASSERT(journal->j_committing_transaction == NULL);
1476         J_ASSERT(journal->j_checkpoint_transactions == NULL);
1477         spin_unlock(&journal->j_list_lock);
1478
1479         /* We can now mark the journal as empty. */
1480         journal->j_tail = 0;
1481         journal->j_tail_sequence = ++journal->j_transaction_sequence;
1482         if (journal->j_sb_buffer) {
1483                 jbd2_journal_update_superblock(journal, 1);
1484                 brelse(journal->j_sb_buffer);
1485         }
1486
1487         if (journal->j_proc_entry)
1488                 jbd2_stats_proc_exit(journal);
1489         if (journal->j_inode)
1490                 iput(journal->j_inode);
1491         if (journal->j_revoke)
1492                 jbd2_journal_destroy_revoke(journal);
1493         kfree(journal->j_wbuf);
1494         kfree(journal);
1495 }
1496
1497
1498 /**
1499  *int jbd2_journal_check_used_features () - Check if features specified are used.
1500  * @journal: Journal to check.
1501  * @compat: bitmask of compatible features
1502  * @ro: bitmask of features that force read-only mount
1503  * @incompat: bitmask of incompatible features
1504  *
1505  * Check whether the journal uses all of a given set of
1506  * features.  Return true (non-zero) if it does.
1507  **/
1508
1509 int jbd2_journal_check_used_features (journal_t *journal, unsigned long compat,
1510                                  unsigned long ro, unsigned long incompat)
1511 {
1512         journal_superblock_t *sb;
1513
1514         if (!compat && !ro && !incompat)
1515                 return 1;
1516         if (journal->j_format_version == 1)
1517                 return 0;
1518
1519         sb = journal->j_superblock;
1520
1521         if (((be32_to_cpu(sb->s_feature_compat) & compat) == compat) &&
1522             ((be32_to_cpu(sb->s_feature_ro_compat) & ro) == ro) &&
1523             ((be32_to_cpu(sb->s_feature_incompat) & incompat) == incompat))
1524                 return 1;
1525
1526         return 0;
1527 }
1528
1529 /**
1530  * int jbd2_journal_check_available_features() - Check feature set in journalling layer
1531  * @journal: Journal to check.
1532  * @compat: bitmask of compatible features
1533  * @ro: bitmask of features that force read-only mount
1534  * @incompat: bitmask of incompatible features
1535  *
1536  * Check whether the journaling code supports the use of
1537  * all of a given set of features on this journal.  Return true
1538  * (non-zero) if it can. */
1539
1540 int jbd2_journal_check_available_features (journal_t *journal, unsigned long compat,
1541                                       unsigned long ro, unsigned long incompat)
1542 {
1543         journal_superblock_t *sb;
1544
1545         if (!compat && !ro && !incompat)
1546                 return 1;
1547
1548         sb = journal->j_superblock;
1549
1550         /* We can support any known requested features iff the
1551          * superblock is in version 2.  Otherwise we fail to support any
1552          * extended sb features. */
1553
1554         if (journal->j_format_version != 2)
1555                 return 0;
1556
1557         if ((compat   & JBD2_KNOWN_COMPAT_FEATURES) == compat &&
1558             (ro       & JBD2_KNOWN_ROCOMPAT_FEATURES) == ro &&
1559             (incompat & JBD2_KNOWN_INCOMPAT_FEATURES) == incompat)
1560                 return 1;
1561
1562         return 0;
1563 }
1564
1565 /**
1566  * int jbd2_journal_set_features () - Mark a given journal feature in the superblock
1567  * @journal: Journal to act on.
1568  * @compat: bitmask of compatible features
1569  * @ro: bitmask of features that force read-only mount
1570  * @incompat: bitmask of incompatible features
1571  *
1572  * Mark a given journal feature as present on the
1573  * superblock.  Returns true if the requested features could be set.
1574  *
1575  */
1576
1577 int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
1578                           unsigned long ro, unsigned long incompat)
1579 {
1580         journal_superblock_t *sb;
1581
1582         if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
1583                 return 1;
1584
1585         if (!jbd2_journal_check_available_features(journal, compat, ro, incompat))
1586                 return 0;
1587
1588         jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
1589                   compat, ro, incompat);
1590
1591         sb = journal->j_superblock;
1592
1593         sb->s_feature_compat    |= cpu_to_be32(compat);
1594         sb->s_feature_ro_compat |= cpu_to_be32(ro);
1595         sb->s_feature_incompat  |= cpu_to_be32(incompat);
1596
1597         return 1;
1598 }
1599
1600 /*
1601  * jbd2_journal_clear_features () - Clear a given journal feature in the
1602  *                                  superblock
1603  * @journal: Journal to act on.
1604  * @compat: bitmask of compatible features
1605  * @ro: bitmask of features that force read-only mount
1606  * @incompat: bitmask of incompatible features
1607  *
1608  * Clear a given journal feature as present on the
1609  * superblock.
1610  */
1611 void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
1612                                 unsigned long ro, unsigned long incompat)
1613 {
1614         journal_superblock_t *sb;
1615
1616         jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
1617                   compat, ro, incompat);
1618
1619         sb = journal->j_superblock;
1620
1621         sb->s_feature_compat    &= ~cpu_to_be32(compat);
1622         sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
1623         sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
1624 }
1625 EXPORT_SYMBOL(jbd2_journal_clear_features);
1626
1627 /**
1628  * int jbd2_journal_update_format () - Update on-disk journal structure.
1629  * @journal: Journal to act on.
1630  *
1631  * Given an initialised but unloaded journal struct, poke about in the
1632  * on-disk structure to update it to the most recent supported version.
1633  */
1634 int jbd2_journal_update_format (journal_t *journal)
1635 {
1636         journal_superblock_t *sb;
1637         int err;
1638
1639         err = journal_get_superblock(journal);
1640         if (err)
1641                 return err;
1642
1643         sb = journal->j_superblock;
1644
1645         switch (be32_to_cpu(sb->s_header.h_blocktype)) {
1646         case JBD2_SUPERBLOCK_V2:
1647                 return 0;
1648         case JBD2_SUPERBLOCK_V1:
1649                 return journal_convert_superblock_v1(journal, sb);
1650         default:
1651                 break;
1652         }
1653         return -EINVAL;
1654 }
1655
1656 static int journal_convert_superblock_v1(journal_t *journal,
1657                                          journal_superblock_t *sb)
1658 {
1659         int offset, blocksize;
1660         struct buffer_head *bh;
1661
1662         printk(KERN_WARNING
1663                 "JBD: Converting superblock from version 1 to 2.\n");
1664
1665         /* Pre-initialise new fields to zero */
1666         offset = ((char *) &(sb->s_feature_compat)) - ((char *) sb);
1667         blocksize = be32_to_cpu(sb->s_blocksize);
1668         memset(&sb->s_feature_compat, 0, blocksize-offset);
1669
1670         sb->s_nr_users = cpu_to_be32(1);
1671         sb->s_header.h_blocktype = cpu_to_be32(JBD2_SUPERBLOCK_V2);
1672         journal->j_format_version = 2;
1673
1674         bh = journal->j_sb_buffer;
1675         BUFFER_TRACE(bh, "marking dirty");
1676         mark_buffer_dirty(bh);
1677         sync_dirty_buffer(bh);
1678         return 0;
1679 }
1680
1681
1682 /**
1683  * int jbd2_journal_flush () - Flush journal
1684  * @journal: Journal to act on.
1685  *
1686  * Flush all data for a given journal to disk and empty the journal.
1687  * Filesystems can use this when remounting readonly to ensure that
1688  * recovery does not need to happen on remount.
1689  */
1690
1691 int jbd2_journal_flush(journal_t *journal)
1692 {
1693         int err = 0;
1694         transaction_t *transaction = NULL;
1695         unsigned long old_tail;
1696
1697         spin_lock(&journal->j_state_lock);
1698
1699         /* Force everything buffered to the log... */
1700         if (journal->j_running_transaction) {
1701                 transaction = journal->j_running_transaction;
1702                 __jbd2_log_start_commit(journal, transaction->t_tid);
1703         } else if (journal->j_committing_transaction)
1704                 transaction = journal->j_committing_transaction;
1705
1706         /* Wait for the log commit to complete... */
1707         if (transaction) {
1708                 tid_t tid = transaction->t_tid;
1709
1710                 spin_unlock(&journal->j_state_lock);
1711                 jbd2_log_wait_commit(journal, tid);
1712         } else {
1713                 spin_unlock(&journal->j_state_lock);
1714         }
1715
1716         /* ...and flush everything in the log out to disk. */
1717         spin_lock(&journal->j_list_lock);
1718         while (!err && journal->j_checkpoint_transactions != NULL) {
1719                 spin_unlock(&journal->j_list_lock);
1720                 err = jbd2_log_do_checkpoint(journal);
1721                 spin_lock(&journal->j_list_lock);
1722         }
1723         spin_unlock(&journal->j_list_lock);
1724         jbd2_cleanup_journal_tail(journal);
1725
1726         /* Finally, mark the journal as really needing no recovery.
1727          * This sets s_start==0 in the underlying superblock, which is
1728          * the magic code for a fully-recovered superblock.  Any future
1729          * commits of data to the journal will restore the current
1730          * s_start value. */
1731         spin_lock(&journal->j_state_lock);
1732         old_tail = journal->j_tail;
1733         journal->j_tail = 0;
1734         spin_unlock(&journal->j_state_lock);
1735         jbd2_journal_update_superblock(journal, 1);
1736         spin_lock(&journal->j_state_lock);
1737         journal->j_tail = old_tail;
1738
1739         J_ASSERT(!journal->j_running_transaction);
1740         J_ASSERT(!journal->j_committing_transaction);
1741         J_ASSERT(!journal->j_checkpoint_transactions);
1742         J_ASSERT(journal->j_head == journal->j_tail);
1743         J_ASSERT(journal->j_tail_sequence == journal->j_transaction_sequence);
1744         spin_unlock(&journal->j_state_lock);
1745         return err;
1746 }
1747
1748 /**
1749  * int jbd2_journal_wipe() - Wipe journal contents
1750  * @journal: Journal to act on.
1751  * @write: flag (see below)
1752  *
1753  * Wipe out all of the contents of a journal, safely.  This will produce
1754  * a warning if the journal contains any valid recovery information.
1755  * Must be called between journal_init_*() and jbd2_journal_load().
1756  *
1757  * If 'write' is non-zero, then we wipe out the journal on disk; otherwise
1758  * we merely suppress recovery.
1759  */
1760
1761 int jbd2_journal_wipe(journal_t *journal, int write)
1762 {
1763         journal_superblock_t *sb;
1764         int err = 0;
1765
1766         J_ASSERT (!(journal->j_flags & JBD2_LOADED));
1767
1768         err = load_superblock(journal);
1769         if (err)
1770                 return err;
1771
1772         sb = journal->j_superblock;
1773
1774         if (!journal->j_tail)
1775                 goto no_recovery;
1776
1777         printk (KERN_WARNING "JBD: %s recovery information on journal\n",
1778                 write ? "Clearing" : "Ignoring");
1779
1780         err = jbd2_journal_skip_recovery(journal);
1781         if (write)
1782                 jbd2_journal_update_superblock(journal, 1);
1783
1784  no_recovery:
1785         return err;
1786 }
1787
1788 /*
1789  * Journal abort has very specific semantics, which we describe
1790  * for journal abort.
1791  *
1792  * Two internal function, which provide abort to te jbd layer
1793  * itself are here.
1794  */
1795
1796 /*
1797  * Quick version for internal journal use (doesn't lock the journal).
1798  * Aborts hard --- we mark the abort as occurred, but do _nothing_ else,
1799  * and don't attempt to make any other journal updates.
1800  */
1801 void __jbd2_journal_abort_hard(journal_t *journal)
1802 {
1803         transaction_t *transaction;
1804
1805         if (journal->j_flags & JBD2_ABORT)
1806                 return;
1807
1808         printk(KERN_ERR "Aborting journal on device %s.\n",
1809                journal->j_devname);
1810
1811         spin_lock(&journal->j_state_lock);
1812         journal->j_flags |= JBD2_ABORT;
1813         transaction = journal->j_running_transaction;
1814         if (transaction)
1815                 __jbd2_log_start_commit(journal, transaction->t_tid);
1816         spin_unlock(&journal->j_state_lock);
1817 }
1818
1819 /* Soft abort: record the abort error status in the journal superblock,
1820  * but don't do any other IO. */
1821 static void __journal_abort_soft (journal_t *journal, int errno)
1822 {
1823         if (journal->j_flags & JBD2_ABORT)
1824                 return;
1825
1826         if (!journal->j_errno)
1827                 journal->j_errno = errno;
1828
1829         __jbd2_journal_abort_hard(journal);
1830
1831         if (errno)
1832                 jbd2_journal_update_superblock(journal, 1);
1833 }
1834
1835 /**
1836  * void jbd2_journal_abort () - Shutdown the journal immediately.
1837  * @journal: the journal to shutdown.
1838  * @errno:   an error number to record in the journal indicating
1839  *           the reason for the shutdown.
1840  *
1841  * Perform a complete, immediate shutdown of the ENTIRE
1842  * journal (not of a single transaction).  This operation cannot be
1843  * undone without closing and reopening the journal.
1844  *
1845  * The jbd2_journal_abort function is intended to support higher level error
1846  * recovery mechanisms such as the ext2/ext3 remount-readonly error
1847  * mode.
1848  *
1849  * Journal abort has very specific semantics.  Any existing dirty,
1850  * unjournaled buffers in the main filesystem will still be written to
1851  * disk by bdflush, but the journaling mechanism will be suspended
1852  * immediately and no further transaction commits will be honoured.
1853  *
1854  * Any dirty, journaled buffers will be written back to disk without
1855  * hitting the journal.  Atomicity cannot be guaranteed on an aborted
1856  * filesystem, but we _do_ attempt to leave as much data as possible
1857  * behind for fsck to use for cleanup.
1858  *
1859  * Any attempt to get a new transaction handle on a journal which is in
1860  * ABORT state will just result in an -EROFS error return.  A
1861  * jbd2_journal_stop on an existing handle will return -EIO if we have
1862  * entered abort state during the update.
1863  *
1864  * Recursive transactions are not disturbed by journal abort until the
1865  * final jbd2_journal_stop, which will receive the -EIO error.
1866  *
1867  * Finally, the jbd2_journal_abort call allows the caller to supply an errno
1868  * which will be recorded (if possible) in the journal superblock.  This
1869  * allows a client to record failure conditions in the middle of a
1870  * transaction without having to complete the transaction to record the
1871  * failure to disk.  ext3_error, for example, now uses this
1872  * functionality.
1873  *
1874  * Errors which originate from within the journaling layer will NOT
1875  * supply an errno; a null errno implies that absolutely no further
1876  * writes are done to the journal (unless there are any already in
1877  * progress).
1878  *
1879  */
1880
1881 void jbd2_journal_abort(journal_t *journal, int errno)
1882 {
1883         __journal_abort_soft(journal, errno);
1884 }
1885
1886 /**
1887  * int jbd2_journal_errno () - returns the journal's error state.
1888  * @journal: journal to examine.
1889  *
1890  * This is the errno numbet set with jbd2_journal_abort(), the last
1891  * time the journal was mounted - if the journal was stopped
1892  * without calling abort this will be 0.
1893  *
1894  * If the journal has been aborted on this mount time -EROFS will
1895  * be returned.
1896  */
1897 int jbd2_journal_errno(journal_t *journal)
1898 {
1899         int err;
1900
1901         spin_lock(&journal->j_state_lock);
1902         if (journal->j_flags & JBD2_ABORT)
1903                 err = -EROFS;
1904         else
1905                 err = journal->j_errno;
1906         spin_unlock(&journal->j_state_lock);
1907         return err;
1908 }
1909
1910 /**
1911  * int jbd2_journal_clear_err () - clears the journal's error state
1912  * @journal: journal to act on.
1913  *
1914  * An error must be cleared or Acked to take a FS out of readonly
1915  * mode.
1916  */
1917 int jbd2_journal_clear_err(journal_t *journal)
1918 {
1919         int err = 0;
1920
1921         spin_lock(&journal->j_state_lock);
1922         if (journal->j_flags & JBD2_ABORT)
1923                 err = -EROFS;
1924         else
1925                 journal->j_errno = 0;
1926         spin_unlock(&journal->j_state_lock);
1927         return err;
1928 }
1929
1930 /**
1931  * void jbd2_journal_ack_err() - Ack journal err.
1932  * @journal: journal to act on.
1933  *
1934  * An error must be cleared or Acked to take a FS out of readonly
1935  * mode.
1936  */
1937 void jbd2_journal_ack_err(journal_t *journal)
1938 {
1939         spin_lock(&journal->j_state_lock);
1940         if (journal->j_errno)
1941                 journal->j_flags |= JBD2_ACK_ERR;
1942         spin_unlock(&journal->j_state_lock);
1943 }
1944
1945 int jbd2_journal_blocks_per_page(struct inode *inode)
1946 {
1947         return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1948 }
1949
1950 /*
1951  * helper functions to deal with 32 or 64bit block numbers.
1952  */
1953 size_t journal_tag_bytes(journal_t *journal)
1954 {
1955         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
1956                 return JBD2_TAG_SIZE64;
1957         else
1958                 return JBD2_TAG_SIZE32;
1959 }
1960
1961 /*
1962  * Journal_head storage management
1963  */
1964 static struct kmem_cache *jbd2_journal_head_cache;
1965 #ifdef CONFIG_JBD2_DEBUG
1966 static atomic_t nr_journal_heads = ATOMIC_INIT(0);
1967 #endif
1968
1969 static int journal_init_jbd2_journal_head_cache(void)
1970 {
1971         int retval;
1972
1973         J_ASSERT(jbd2_journal_head_cache == NULL);
1974         jbd2_journal_head_cache = kmem_cache_create("jbd2_journal_head",
1975                                 sizeof(struct journal_head),
1976                                 0,              /* offset */
1977                                 SLAB_TEMPORARY, /* flags */
1978                                 NULL);          /* ctor */
1979         retval = 0;
1980         if (!jbd2_journal_head_cache) {
1981                 retval = -ENOMEM;
1982                 printk(KERN_EMERG "JBD: no memory for journal_head cache\n");
1983         }
1984         return retval;
1985 }
1986
1987 static void jbd2_journal_destroy_jbd2_journal_head_cache(void)
1988 {
1989         if (jbd2_journal_head_cache) {
1990                 kmem_cache_destroy(jbd2_journal_head_cache);
1991                 jbd2_journal_head_cache = NULL;
1992         }
1993 }
1994
1995 /*
1996  * journal_head splicing and dicing
1997  */
1998 static struct journal_head *journal_alloc_journal_head(void)
1999 {
2000         struct journal_head *ret;
2001         static unsigned long last_warning;
2002
2003 #ifdef CONFIG_JBD2_DEBUG
2004         atomic_inc(&nr_journal_heads);
2005 #endif
2006         ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
2007         if (!ret) {
2008                 jbd_debug(1, "out of memory for journal_head\n");
2009                 if (time_after(jiffies, last_warning + 5*HZ)) {
2010                         printk(KERN_NOTICE "ENOMEM in %s, retrying.\n",
2011                                __func__);
2012                         last_warning = jiffies;
2013                 }
2014                 while (!ret) {
2015                         yield();
2016                         ret = kmem_cache_alloc(jbd2_journal_head_cache, GFP_NOFS);
2017                 }
2018         }
2019         return ret;
2020 }
2021
2022 static void journal_free_journal_head(struct journal_head *jh)
2023 {
2024 #ifdef CONFIG_JBD2_DEBUG
2025         atomic_dec(&nr_journal_heads);
2026         memset(jh, JBD2_POISON_FREE, sizeof(*jh));
2027 #endif
2028         kmem_cache_free(jbd2_journal_head_cache, jh);
2029 }
2030
2031 /*
2032  * A journal_head is attached to a buffer_head whenever JBD has an
2033  * interest in the buffer.
2034  *
2035  * Whenever a buffer has an attached journal_head, its ->b_state:BH_JBD bit
2036  * is set.  This bit is tested in core kernel code where we need to take
2037  * JBD-specific actions.  Testing the zeroness of ->b_private is not reliable
2038  * there.
2039  *
2040  * When a buffer has its BH_JBD bit set, its ->b_count is elevated by one.
2041  *
2042  * When a buffer has its BH_JBD bit set it is immune from being released by
2043  * core kernel code, mainly via ->b_count.
2044  *
2045  * A journal_head may be detached from its buffer_head when the journal_head's
2046  * b_transaction, b_cp_transaction and b_next_transaction pointers are NULL.
2047  * Various places in JBD call jbd2_journal_remove_journal_head() to indicate that the
2048  * journal_head can be dropped if needed.
2049  *
2050  * Various places in the kernel want to attach a journal_head to a buffer_head
2051  * _before_ attaching the journal_head to a transaction.  To protect the
2052  * journal_head in this situation, jbd2_journal_add_journal_head elevates the
2053  * journal_head's b_jcount refcount by one.  The caller must call
2054  * jbd2_journal_put_journal_head() to undo this.
2055  *
2056  * So the typical usage would be:
2057  *
2058  *      (Attach a journal_head if needed.  Increments b_jcount)
2059  *      struct journal_head *jh = jbd2_journal_add_journal_head(bh);
2060  *      ...
2061  *      jh->b_transaction = xxx;
2062  *      jbd2_journal_put_journal_head(jh);
2063  *
2064  * Now, the journal_head's b_jcount is zero, but it is safe from being released
2065  * because it has a non-zero b_transaction.
2066  */
2067
2068 /*
2069  * Give a buffer_head a journal_head.
2070  *
2071  * Doesn't need the journal lock.
2072  * May sleep.
2073  */
2074 struct journal_head *jbd2_journal_add_journal_head(struct buffer_head *bh)
2075 {
2076         struct journal_head *jh;
2077         struct journal_head *new_jh = NULL;
2078
2079 repeat:
2080         if (!buffer_jbd(bh)) {
2081                 new_jh = journal_alloc_journal_head();
2082                 memset(new_jh, 0, sizeof(*new_jh));
2083         }
2084
2085         jbd_lock_bh_journal_head(bh);
2086         if (buffer_jbd(bh)) {
2087                 jh = bh2jh(bh);
2088         } else {
2089                 J_ASSERT_BH(bh,
2090                         (atomic_read(&bh->b_count) > 0) ||
2091                         (bh->b_page && bh->b_page->mapping));
2092
2093                 if (!new_jh) {
2094                         jbd_unlock_bh_journal_head(bh);
2095                         goto repeat;
2096                 }
2097
2098                 jh = new_jh;
2099                 new_jh = NULL;          /* We consumed it */
2100                 set_buffer_jbd(bh);
2101                 bh->b_private = jh;
2102                 jh->b_bh = bh;
2103                 get_bh(bh);
2104                 BUFFER_TRACE(bh, "added journal_head");
2105         }
2106         jh->b_jcount++;
2107         jbd_unlock_bh_journal_head(bh);
2108         if (new_jh)
2109                 journal_free_journal_head(new_jh);
2110         return bh->b_private;
2111 }
2112
2113 /*
2114  * Grab a ref against this buffer_head's journal_head.  If it ended up not
2115  * having a journal_head, return NULL
2116  */
2117 struct journal_head *jbd2_journal_grab_journal_head(struct buffer_head *bh)
2118 {
2119         struct journal_head *jh = NULL;
2120
2121         jbd_lock_bh_journal_head(bh);
2122         if (buffer_jbd(bh)) {
2123                 jh = bh2jh(bh);
2124                 jh->b_jcount++;
2125         }
2126         jbd_unlock_bh_journal_head(bh);
2127         return jh;
2128 }
2129
2130 static void __journal_remove_journal_head(struct buffer_head *bh)
2131 {
2132         struct journal_head *jh = bh2jh(bh);
2133
2134         J_ASSERT_JH(jh, jh->b_jcount >= 0);
2135
2136         get_bh(bh);
2137         if (jh->b_jcount == 0) {
2138                 if (jh->b_transaction == NULL &&
2139                                 jh->b_next_transaction == NULL &&
2140                                 jh->b_cp_transaction == NULL) {
2141                         J_ASSERT_JH(jh, jh->b_jlist == BJ_None);
2142                         J_ASSERT_BH(bh, buffer_jbd(bh));
2143                         J_ASSERT_BH(bh, jh2bh(jh) == bh);
2144                         BUFFER_TRACE(bh, "remove journal_head");
2145                         if (jh->b_frozen_data) {
2146                                 printk(KERN_WARNING "%s: freeing "
2147                                                 "b_frozen_data\n",
2148                                                 __func__);
2149                                 jbd2_free(jh->b_frozen_data, bh->b_size);
2150                         }
2151                         if (jh->b_committed_data) {
2152                                 printk(KERN_WARNING "%s: freeing "
2153                                                 "b_committed_data\n",
2154                                                 __func__);
2155                                 jbd2_free(jh->b_committed_data, bh->b_size);
2156                         }
2157                         bh->b_private = NULL;
2158                         jh->b_bh = NULL;        /* debug, really */
2159                         clear_buffer_jbd(bh);
2160                         __brelse(bh);
2161                         journal_free_journal_head(jh);
2162                 } else {
2163                         BUFFER_TRACE(bh, "journal_head was locked");
2164                 }
2165         }
2166 }
2167
2168 /*
2169  * jbd2_journal_remove_journal_head(): if the buffer isn't attached to a transaction
2170  * and has a zero b_jcount then remove and release its journal_head.   If we did
2171  * see that the buffer is not used by any transaction we also "logically"
2172  * decrement ->b_count.
2173  *
2174  * We in fact take an additional increment on ->b_count as a convenience,
2175  * because the caller usually wants to do additional things with the bh
2176  * after calling here.
2177  * The caller of jbd2_journal_remove_journal_head() *must* run __brelse(bh) at some
2178  * time.  Once the caller has run __brelse(), the buffer is eligible for
2179  * reaping by try_to_free_buffers().
2180  */
2181 void jbd2_journal_remove_journal_head(struct buffer_head *bh)
2182 {
2183         jbd_lock_bh_journal_head(bh);
2184         __journal_remove_journal_head(bh);
2185         jbd_unlock_bh_journal_head(bh);
2186 }
2187
2188 /*
2189  * Drop a reference on the passed journal_head.  If it fell to zero then try to
2190  * release the journal_head from the buffer_head.
2191  */
2192 void jbd2_journal_put_journal_head(struct journal_head *jh)
2193 {
2194         struct buffer_head *bh = jh2bh(jh);
2195
2196         jbd_lock_bh_journal_head(bh);
2197         J_ASSERT_JH(jh, jh->b_jcount > 0);
2198         --jh->b_jcount;
2199         if (!jh->b_jcount && !jh->b_transaction) {
2200                 __journal_remove_journal_head(bh);
2201                 __brelse(bh);
2202         }
2203         jbd_unlock_bh_journal_head(bh);
2204 }
2205
2206 /*
2207  * Initialize jbd inode head
2208  */
2209 void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode)
2210 {
2211         jinode->i_transaction = NULL;
2212         jinode->i_next_transaction = NULL;
2213         jinode->i_vfs_inode = inode;
2214         jinode->i_flags = 0;
2215         INIT_LIST_HEAD(&jinode->i_list);
2216 }
2217
2218 /*
2219  * Function to be called before we start removing inode from memory (i.e.,
2220  * clear_inode() is a fine place to be called from). It removes inode from
2221  * transaction's lists.
2222  */
2223 void jbd2_journal_release_jbd_inode(journal_t *journal,
2224                                     struct jbd2_inode *jinode)
2225 {
2226         int writeout = 0;
2227
2228         if (!journal)
2229                 return;
2230 restart:
2231         spin_lock(&journal->j_list_lock);
2232         /* Is commit writing out inode - we have to wait */
2233         if (jinode->i_flags & JI_COMMIT_RUNNING) {
2234                 wait_queue_head_t *wq;
2235                 DEFINE_WAIT_BIT(wait, &jinode->i_flags, __JI_COMMIT_RUNNING);
2236                 wq = bit_waitqueue(&jinode->i_flags, __JI_COMMIT_RUNNING);
2237                 prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
2238                 spin_unlock(&journal->j_list_lock);
2239                 schedule();
2240                 finish_wait(wq, &wait.wait);
2241                 goto restart;
2242         }
2243
2244         /* Do we need to wait for data writeback? */
2245         if (journal->j_committing_transaction == jinode->i_transaction)
2246                 writeout = 1;
2247         if (jinode->i_transaction) {
2248                 list_del(&jinode->i_list);
2249                 jinode->i_transaction = NULL;
2250         }
2251         spin_unlock(&journal->j_list_lock);
2252 }
2253
2254 /*
2255  * debugfs tunables
2256  */
2257 #ifdef CONFIG_JBD2_DEBUG
2258 u8 jbd2_journal_enable_debug __read_mostly;
2259 EXPORT_SYMBOL(jbd2_journal_enable_debug);
2260
2261 #define JBD2_DEBUG_NAME "jbd2-debug"
2262
2263 static struct dentry *jbd2_debugfs_dir;
2264 static struct dentry *jbd2_debug;
2265
2266 static void __init jbd2_create_debugfs_entry(void)
2267 {
2268         jbd2_debugfs_dir = debugfs_create_dir("jbd2", NULL);
2269         if (jbd2_debugfs_dir)
2270                 jbd2_debug = debugfs_create_u8(JBD2_DEBUG_NAME, S_IRUGO,
2271                                                jbd2_debugfs_dir,
2272                                                &jbd2_journal_enable_debug);
2273 }
2274
2275 static void __exit jbd2_remove_debugfs_entry(void)
2276 {
2277         debugfs_remove(jbd2_debug);
2278         debugfs_remove(jbd2_debugfs_dir);
2279 }
2280
2281 #else
2282
2283 static void __init jbd2_create_debugfs_entry(void)
2284 {
2285 }
2286
2287 static void __exit jbd2_remove_debugfs_entry(void)
2288 {
2289 }
2290
2291 #endif
2292
2293 #ifdef CONFIG_PROC_FS
2294
2295 #define JBD2_STATS_PROC_NAME "fs/jbd2"
2296
2297 static void __init jbd2_create_jbd_stats_proc_entry(void)
2298 {
2299         proc_jbd2_stats = proc_mkdir(JBD2_STATS_PROC_NAME, NULL);
2300 }
2301
2302 static void __exit jbd2_remove_jbd_stats_proc_entry(void)
2303 {
2304         if (proc_jbd2_stats)
2305                 remove_proc_entry(JBD2_STATS_PROC_NAME, NULL);
2306 }
2307
2308 #else
2309
2310 #define jbd2_create_jbd_stats_proc_entry() do {} while (0)
2311 #define jbd2_remove_jbd_stats_proc_entry() do {} while (0)
2312
2313 #endif
2314
2315 struct kmem_cache *jbd2_handle_cache;
2316
2317 static int __init journal_init_handle_cache(void)
2318 {
2319         jbd2_handle_cache = kmem_cache_create("jbd2_journal_handle",
2320                                 sizeof(handle_t),
2321                                 0,              /* offset */
2322                                 SLAB_TEMPORARY, /* flags */
2323                                 NULL);          /* ctor */
2324         if (jbd2_handle_cache == NULL) {
2325                 printk(KERN_EMERG "JBD: failed to create handle cache\n");
2326                 return -ENOMEM;
2327         }
2328         return 0;
2329 }
2330
2331 static void jbd2_journal_destroy_handle_cache(void)
2332 {
2333         if (jbd2_handle_cache)
2334                 kmem_cache_destroy(jbd2_handle_cache);
2335 }
2336
2337 /*
2338  * Module startup and shutdown
2339  */
2340
2341 static int __init journal_init_caches(void)
2342 {
2343         int ret;
2344
2345         ret = jbd2_journal_init_revoke_caches();
2346         if (ret == 0)
2347                 ret = journal_init_jbd2_journal_head_cache();
2348         if (ret == 0)
2349                 ret = journal_init_handle_cache();
2350         return ret;
2351 }
2352
2353 static void jbd2_journal_destroy_caches(void)
2354 {
2355         jbd2_journal_destroy_revoke_caches();
2356         jbd2_journal_destroy_jbd2_journal_head_cache();
2357         jbd2_journal_destroy_handle_cache();
2358 }
2359
2360 static int __init journal_init(void)
2361 {
2362         int ret;
2363
2364         BUILD_BUG_ON(sizeof(struct journal_superblock_s) != 1024);
2365
2366         ret = journal_init_caches();
2367         if (ret == 0) {
2368                 jbd2_create_debugfs_entry();
2369                 jbd2_create_jbd_stats_proc_entry();
2370         } else {
2371                 jbd2_journal_destroy_caches();
2372         }
2373         return ret;
2374 }
2375
2376 static void __exit journal_exit(void)
2377 {
2378 #ifdef CONFIG_JBD2_DEBUG
2379         int n = atomic_read(&nr_journal_heads);
2380         if (n)
2381                 printk(KERN_EMERG "JBD: leaked %d journal_heads!\n", n);
2382 #endif
2383         jbd2_remove_debugfs_entry();
2384         jbd2_remove_jbd_stats_proc_entry();
2385         jbd2_journal_destroy_caches();
2386 }
2387
2388 MODULE_LICENSE("GPL");
2389 module_init(journal_init);
2390 module_exit(journal_exit);
2391