LCOV - code coverage report
Current view: top level - lkbce/fs/jbd - transaction.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 0 877 0.0 %
Date: 2017-01-25 Functions: 0 33 0.0 %

          Line data    Source code
       1             : /*
       2             :  * linux/fs/jbd/transaction.c
       3             :  *
       4             :  * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
       5             :  *
       6             :  * Copyright 1998 Red Hat corp --- All Rights Reserved
       7             :  *
       8             :  * This file is part of the Linux kernel and is made available under
       9             :  * the terms of the GNU General Public License, version 2, or at your
      10             :  * option, any later version, incorporated herein by reference.
      11             :  *
      12             :  * Generic filesystem transaction handling code; part of the ext2fs
      13             :  * journaling system.
      14             :  *
      15             :  * This file manages transactions (compound commits managed by the
      16             :  * journaling code) and handles (individual atomic operations by the
      17             :  * filesystem).
      18             :  */
      19             : 
      20             : #include <linux/time.h>
      21             : #include <linux/fs.h>
      22             : #include <linux/jbd.h>
      23             : #include <linux/errno.h>
      24             : #include <linux/slab.h>
      25             : #include <linux/timer.h>
      26             : #include <linux/mm.h>
      27             : #include <linux/highmem.h>
      28             : #include <linux/hrtimer.h>
      29             : 
      30             : static void __journal_temp_unlink_buffer(struct journal_head *jh);
      31             : 
      32             : /*
      33             :  * get_transaction: obtain a new transaction_t object.
      34             :  *
      35             :  * Simply allocate and initialise a new transaction.  Create it in
      36             :  * RUNNING state and add it to the current journal (which should not
      37             :  * have an existing running transaction: we only make a new transaction
      38             :  * once we have started to commit the old one).
      39             :  *
      40             :  * Preconditions:
      41             :  *      The journal MUST be locked.  We don't perform atomic mallocs on the
      42             :  *      new transaction and we can't block without protecting against other
      43             :  *      processes trying to touch the journal while it is in transition.
      44             :  *
      45             :  * Called under j_state_lock
      46             :  */
      47             : 
      48             : static transaction_t *
      49             : get_transaction(journal_t *journal, transaction_t *transaction)
      50             : {
      51           0 :         transaction->t_journal = journal;
      52           0 :         transaction->t_state = T_RUNNING;
      53           0 :         transaction->t_start_time = ktime_get();
      54           0 :         transaction->t_tid = journal->j_transaction_sequence++;
      55           0 :         transaction->t_expires = jiffies + journal->j_commit_interval;
      56           0 :         spin_lock_init(&transaction->t_handle_lock);
      57             : 
      58             :         /* Set up the commit timer for the new transaction. */
      59           0 :         journal->j_commit_timer.expires =
      60             :                                 round_jiffies_up(transaction->t_expires);
      61           0 :         add_timer(&journal->j_commit_timer);
      62             : 
      63           0 :         J_ASSERT(journal->j_running_transaction == NULL);
      64           0 :         journal->j_running_transaction = transaction;
      65             : 
      66           0 :         return transaction;
      67             : }
      68             : 
      69             : /*
      70             :  * Handle management.
      71             :  *
      72             :  * A handle_t is an object which represents a single atomic update to a
      73             :  * filesystem, and which tracks all of the modifications which form part
      74             :  * of that one update.
      75             :  */
      76             : 
      77             : /*
      78             :  * start_this_handle: Given a handle, deal with any locking or stalling
      79             :  * needed to make sure that there is enough journal space for the handle
      80             :  * to begin.  Attach the handle to a transaction and set up the
      81             :  * transaction's buffer credits.
      82             :  */
      83             : 
      84             : static int start_this_handle(journal_t *journal, handle_t *handle)
      85             : {
      86           0 :         transaction_t *transaction;
      87           0 :         int needed;
      88           0 :         int nblocks = handle->h_buffer_credits;
      89           0 :         transaction_t *new_transaction = NULL;
      90           0 :         int ret = 0;
      91           0 : 
      92           0 :         if (nblocks > journal->j_max_transaction_buffers) {
      93           0 :                 printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n",
      94           0 :                        current->comm, nblocks,
      95           0 :                        journal->j_max_transaction_buffers);
      96           0 :                 ret = -ENOSPC;
      97           0 :                 goto out;
      98           0 :         }
      99           0 : 
     100           0 : alloc_transaction:
     101           0 :         if (!journal->j_running_transaction) {
     102           0 :                 new_transaction = kzalloc(sizeof(*new_transaction),
     103             :                                                 GFP_NOFS|__GFP_NOFAIL);
     104           0 :                 if (!new_transaction) {
     105           0 :                         ret = -ENOMEM;
     106           0 :                         goto out;
     107             :                 }
     108             :         }
     109             : 
     110             :         jbd_debug(3, "New handle %p going live.\n", handle);
     111             : 
     112             : repeat:
     113           0 : 
     114             :         /*
     115             :          * We need to hold j_state_lock until t_updates has been incremented,
     116             :          * for proper journal barrier handling
     117             :          */
     118           0 :         spin_lock(&journal->j_state_lock);
     119             : repeat_locked:
     120           0 :         if (is_journal_aborted(journal) ||
     121             :             (journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
     122           0 :                 spin_unlock(&journal->j_state_lock);
     123           0 :                 ret = -EROFS;
     124           0 :                 goto out;
     125             :         }
     126             : 
     127             :         /* Wait on the journal's transaction barrier if necessary */
     128           0 :         if (journal->j_barrier_count) {
     129           0 :                 spin_unlock(&journal->j_state_lock);
     130           0 :                 wait_event(journal->j_wait_transaction_locked,
     131           0 :                                 journal->j_barrier_count == 0);
     132           0 :                 goto repeat;
     133             :         }
     134             : 
     135           0 :         if (!journal->j_running_transaction) {
     136           0 :                 if (!new_transaction) {
     137           0 :                         spin_unlock(&journal->j_state_lock);
     138           0 :                         goto alloc_transaction;
     139             :                 }
     140           0 :                 get_transaction(journal, new_transaction);
     141           0 :                 new_transaction = NULL;
     142             :         }
     143             : 
     144           0 :         transaction = journal->j_running_transaction;
     145             : 
     146             :         /*
     147             :          * If the current transaction is locked down for commit, wait for the
     148             :          * lock to be released.
     149             :          */
     150           0 :         if (transaction->t_state == T_LOCKED) {
     151           0 :                 DEFINE_WAIT(wait);
     152             : 
     153           0 :                 prepare_to_wait(&journal->j_wait_transaction_locked,
     154             :                                         &wait, TASK_UNINTERRUPTIBLE);
     155           0 :                 spin_unlock(&journal->j_state_lock);
     156           0 :                 schedule();
     157           0 :                 finish_wait(&journal->j_wait_transaction_locked, &wait);
     158           0 :                 goto repeat;
     159             :         }
     160             : 
     161             :         /*
     162             :          * If there is not enough space left in the log to write all potential
     163             :          * buffers requested by this operation, we need to stall pending a log
     164             :          * checkpoint to free some more log space.
     165             :          */
     166           0 :         spin_lock(&transaction->t_handle_lock);
     167           0 :         needed = transaction->t_outstanding_credits + nblocks;
     168             : 
     169           0 :         if (needed > journal->j_max_transaction_buffers) {
     170             :                 /*
     171             :                  * If the current transaction is already too large, then start
     172             :                  * to commit it: we can then go back and attach this handle to
     173             :                  * a new transaction.
     174             :                  */
     175           0 :                 DEFINE_WAIT(wait);
     176             : 
     177             :                 jbd_debug(2, "Handle %p starting new commit...\n", handle);
     178           0 :                 spin_unlock(&transaction->t_handle_lock);
     179           0 :                 prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
     180             :                                 TASK_UNINTERRUPTIBLE);
     181           0 :                 __log_start_commit(journal, transaction->t_tid);
     182           0 :                 spin_unlock(&journal->j_state_lock);
     183           0 :                 schedule();
     184           0 :                 finish_wait(&journal->j_wait_transaction_locked, &wait);
     185           0 :                 goto repeat;
     186             :         }
     187             : 
     188             :         /*
     189             :          * The commit code assumes that it can get enough log space
     190             :          * without forcing a checkpoint.  This is *critical* for
     191             :          * correctness: a checkpoint of a buffer which is also
     192             :          * associated with a committing transaction creates a deadlock,
     193             :          * so commit simply cannot force through checkpoints.
     194             :          *
     195             :          * We must therefore ensure the necessary space in the journal
     196             :          * *before* starting to dirty potentially checkpointed buffers
     197             :          * in the new transaction.
     198             :          *
     199             :          * The worst part is, any transaction currently committing can
     200             :          * reduce the free space arbitrarily.  Be careful to account for
     201             :          * those buffers when checkpointing.
     202             :          */
     203             : 
     204             :         /*
     205             :          * @@@ AKPM: This seems rather over-defensive.  We're giving commit
     206             :          * a _lot_ of headroom: 1/4 of the journal plus the size of
     207             :          * the committing transaction.  Really, we only need to give it
     208             :          * committing_transaction->t_outstanding_credits plus "enough" for
     209             :          * the log control blocks.
     210             :          * Also, this test is inconsitent with the matching one in
     211             :          * journal_extend().
     212             :          */
     213           0 :         if (__log_space_left(journal) < jbd_space_needed(journal)) {
     214             :                 jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
     215           0 :                 spin_unlock(&transaction->t_handle_lock);
     216           0 :                 __log_wait_for_space(journal);
     217           0 :                 goto repeat_locked;
     218             :         }
     219             : 
     220             :         /* OK, account for the buffers that this operation expects to
     221             :          * use and add the handle to the running transaction. */
     222             : 
     223           0 :         handle->h_transaction = transaction;
     224           0 :         transaction->t_outstanding_credits += nblocks;
     225           0 :         transaction->t_updates++;
     226           0 :         transaction->t_handle_count++;
     227             :         jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
     228             :                   handle, nblocks, transaction->t_outstanding_credits,
     229             :                   __log_space_left(journal));
     230           0 :         spin_unlock(&transaction->t_handle_lock);
     231           0 :         spin_unlock(&journal->j_state_lock);
     232             : 
     233           0 :         lock_map_acquire(&handle->h_lockdep_map);
     234             : out:
     235           0 :         if (unlikely(new_transaction))          /* It's usually NULL */
     236           0 :                 kfree(new_transaction);
     237           0 :         return ret;
     238             : }
     239             : 
     240             : static struct lock_class_key jbd_handle_key;
     241             : 
     242             : /* Allocate a new handle.  This should probably be in a slab... */
     243             : static handle_t *new_handle(int nblocks)
     244             : {
     245           0 :         handle_t *handle = jbd_alloc_handle(GFP_NOFS);
     246           0 :         if (!handle)
     247           0 :                 return NULL;
     248           0 :         memset(handle, 0, sizeof(*handle));
     249           0 :         handle->h_buffer_credits = nblocks;
     250           0 :         handle->h_ref = 1;
     251             : 
     252             :         lockdep_init_map(&handle->h_lockdep_map, "jbd_handle", &jbd_handle_key, 0);
     253             : 
     254           0 :         return handle;
     255             : }
     256             : 
     257             : /**
     258             :  * handle_t *journal_start() - Obtain a new handle.
     259             :  * @journal: Journal to start transaction on.
     260             :  * @nblocks: number of block buffer we might modify
     261             :  *
     262             :  * We make sure that the transaction can guarantee at least nblocks of
     263             :  * modified buffers in the log.  We block until the log can guarantee
     264             :  * that much space.
     265             :  *
     266             :  * This function is visible to journal users (like ext3fs), so is not
     267             :  * called with the journal already locked.
     268             :  *
     269             :  * Return a pointer to a newly allocated handle, or NULL on failure
     270             :  */
     271             : handle_t *journal_start(journal_t *journal, int nblocks)
     272             : {
     273           0 :         handle_t *handle = journal_current_handle();
     274           0 :         int err;
     275           0 : 
     276           0 :         if (!journal)
     277           0 :                 return ERR_PTR(-EROFS);
     278           0 : 
     279           0 :         if (handle) {
     280           0 :                 J_ASSERT(handle->h_transaction->t_journal == journal);
     281           0 :                 handle->h_ref++;
     282           0 :                 return handle;
     283             :         }
     284             : 
     285           0 :         handle = new_handle(nblocks);
     286           0 :         if (!handle)
     287           0 :                 return ERR_PTR(-ENOMEM);
     288             : 
     289           0 :         current->journal_info = handle;
     290             : 
     291           0 :         err = start_this_handle(journal, handle);
     292           0 :         if (err < 0) {
     293           0 :                 jbd_free_handle(handle);
     294           0 :                 current->journal_info = NULL;
     295           0 :                 handle = ERR_PTR(err);
     296           0 :                 goto out;
     297             :         }
     298             : out:
     299           0 :         return handle;
     300           0 : }
     301             : 
     302             : /**
     303             :  * int journal_extend() - extend buffer credits.
     304             :  * @handle:  handle to 'extend'
     305             :  * @nblocks: nr blocks to try to extend by.
     306             :  *
     307             :  * Some transactions, such as large extends and truncates, can be done
     308             :  * atomically all at once or in several stages.  The operation requests
     309             :  * a credit for a number of buffer modications in advance, but can
     310             :  * extend its credit if it needs more.
     311             :  *
     312             :  * journal_extend tries to give the running handle more buffer credits.
     313             :  * It does not guarantee that allocation - this is a best-effort only.
     314             :  * The calling process MUST be able to deal cleanly with a failure to
     315             :  * extend here.
     316             :  *
     317             :  * Return 0 on success, non-zero on failure.
     318             :  *
     319             :  * return code < 0 implies an error
     320             :  * return code > 0 implies normal transaction-full status.
     321             :  */
     322             : int journal_extend(handle_t *handle, int nblocks)
     323             : {
     324           0 :         transaction_t *transaction = handle->h_transaction;
     325           0 :         journal_t *journal = transaction->t_journal;
     326           0 :         int result;
     327           0 :         int wanted;
     328           0 : 
     329           0 :         result = -EIO;
     330           0 :         if (is_handle_aborted(handle))
     331           0 :                 goto out;
     332             : 
     333           0 :         result = 1;
     334             : 
     335           0 :         spin_lock(&journal->j_state_lock);
     336             : 
     337             :         /* Don't extend a locked-down transaction! */
     338           0 :         if (handle->h_transaction->t_state != T_RUNNING) {
     339             :                 jbd_debug(3, "denied handle %p %d blocks: "
     340             :                           "transaction not running\n", handle, nblocks);
     341           0 :                 goto error_out;
     342             :         }
     343             : 
     344           0 :         spin_lock(&transaction->t_handle_lock);
     345           0 :         wanted = transaction->t_outstanding_credits + nblocks;
     346             : 
     347           0 :         if (wanted > journal->j_max_transaction_buffers) {
     348             :                 jbd_debug(3, "denied handle %p %d blocks: "
     349             :                           "transaction too large\n", handle, nblocks);
     350           0 :                 goto unlock;
     351             :         }
     352             : 
     353           0 :         if (wanted > __log_space_left(journal)) {
     354             :                 jbd_debug(3, "denied handle %p %d blocks: "
     355             :                           "insufficient log space\n", handle, nblocks);
     356           0 :                 goto unlock;
     357             :         }
     358             : 
     359           0 :         handle->h_buffer_credits += nblocks;
     360           0 :         transaction->t_outstanding_credits += nblocks;
     361           0 :         result = 0;
     362           0 : 
     363             :         jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
     364             : unlock:
     365           0 :         spin_unlock(&transaction->t_handle_lock);
     366             : error_out:
     367           0 :         spin_unlock(&journal->j_state_lock);
     368             : out:
     369           0 :         return result;
     370             : }
     371             : 
     372             : 
     373             : /**
     374             :  * int journal_restart() - restart a handle.
     375             :  * @handle:  handle to restart
     376             :  * @nblocks: nr credits requested
     377             :  *
     378             :  * Restart a handle for a multi-transaction filesystem
     379             :  * operation.
     380             :  *
     381             :  * If the journal_extend() call above fails to grant new buffer credits
     382             :  * to a running handle, a call to journal_restart will commit the
     383             :  * handle's transaction so far and reattach the handle to a new
     384             :  * transaction capabable of guaranteeing the requested number of
     385             :  * credits.
     386             :  */
     387             : 
     388             : int journal_restart(handle_t *handle, int nblocks)
     389             : {
     390           0 :         transaction_t *transaction = handle->h_transaction;
     391           0 :         journal_t *journal = transaction->t_journal;
     392           0 :         int ret;
     393           0 : 
     394           0 :         /* If we've had an abort of any type, don't even think about
     395           0 :          * actually doing the restart! */
     396           0 :         if (is_handle_aborted(handle))
     397           0 :                 return 0;
     398             : 
     399             :         /*
     400             :          * First unlink the handle from its current transaction, and start the
     401             :          * commit on that.
     402             :          */
     403           0 :         J_ASSERT(transaction->t_updates > 0);
     404           0 :         J_ASSERT(journal_current_handle() == handle);
     405             : 
     406           0 :         spin_lock(&journal->j_state_lock);
     407           0 :         spin_lock(&transaction->t_handle_lock);
     408           0 :         transaction->t_outstanding_credits -= handle->h_buffer_credits;
     409           0 :         transaction->t_updates--;
     410             : 
     411           0 :         if (!transaction->t_updates)
     412           0 :                 wake_up(&journal->j_wait_updates);
     413           0 :         spin_unlock(&transaction->t_handle_lock);
     414             : 
     415             :         jbd_debug(2, "restarting handle %p\n", handle);
     416           0 :         __log_start_commit(journal, transaction->t_tid);
     417           0 :         spin_unlock(&journal->j_state_lock);
     418             : 
     419             :         lock_map_release(&handle->h_lockdep_map);
     420           0 :         handle->h_buffer_credits = nblocks;
     421           0 :         ret = start_this_handle(journal, handle);
     422           0 :         return ret;
     423             : }
     424             : 
     425             : 
     426             : /**
     427             :  * void journal_lock_updates () - establish a transaction barrier.
     428             :  * @journal:  Journal to establish a barrier on.
     429             :  *
     430             :  * This locks out any further updates from being started, and blocks
     431             :  * until all existing updates have completed, returning only once the
     432             :  * journal is in a quiescent state with no updates running.
     433             :  *
     434             :  * The journal lock should not be held on entry.
     435             :  */
     436             : void journal_lock_updates(journal_t *journal)
     437             : {
     438           0 :         DEFINE_WAIT(wait);
     439           0 : 
     440           0 :         spin_lock(&journal->j_state_lock);
     441           0 :         ++journal->j_barrier_count;
     442             : 
     443           0 :         /* Wait until there are no running updates */
     444             :         while (1) {
     445           0 :                 transaction_t *transaction = journal->j_running_transaction;
     446             : 
     447           0 :                 if (!transaction)
     448           0 :                         break;
     449             : 
     450           0 :                 spin_lock(&transaction->t_handle_lock);
     451           0 :                 if (!transaction->t_updates) {
     452           0 :                         spin_unlock(&transaction->t_handle_lock);
     453           0 :                         break;
     454             :                 }
     455           0 :                 prepare_to_wait(&journal->j_wait_updates, &wait,
     456             :                                 TASK_UNINTERRUPTIBLE);
     457           0 :                 spin_unlock(&transaction->t_handle_lock);
     458           0 :                 spin_unlock(&journal->j_state_lock);
     459           0 :                 schedule();
     460           0 :                 finish_wait(&journal->j_wait_updates, &wait);
     461           0 :                 spin_lock(&journal->j_state_lock);
     462           0 :         }
     463           0 :         spin_unlock(&journal->j_state_lock);
     464             : 
     465             :         /*
     466             :          * We have now established a barrier against other normal updates, but
     467             :          * we also need to barrier against other journal_lock_updates() calls
     468             :          * to make sure that we serialise special journal-locked operations
     469             :          * too.
     470             :          */
     471           0 :         mutex_lock(&journal->j_barrier);
     472           0 : }
     473             : 
     474             : /**
     475             :  * void journal_unlock_updates (journal_t* journal) - release barrier
     476             :  * @journal:  Journal to release the barrier on.
     477             :  *
     478             :  * Release a transaction barrier obtained with journal_lock_updates().
     479             :  *
     480             :  * Should be called without the journal lock held.
     481             :  */
     482             : void journal_unlock_updates (journal_t *journal)
     483             : {
     484           0 :         J_ASSERT(journal->j_barrier_count != 0);
     485             : 
     486           0 :         mutex_unlock(&journal->j_barrier);
     487           0 :         spin_lock(&journal->j_state_lock);
     488           0 :         --journal->j_barrier_count;
     489           0 :         spin_unlock(&journal->j_state_lock);
     490           0 :         wake_up(&journal->j_wait_transaction_locked);
     491           0 : }
     492             : 
     493             : static void warn_dirty_buffer(struct buffer_head *bh)
     494             : {
     495           0 :         char b[BDEVNAME_SIZE];
     496           0 : 
     497           0 :         printk(KERN_WARNING
     498             :                "JBD: Spotted dirty metadata buffer (dev = %s, blocknr = %llu). "
     499             :                "There's a risk of filesystem corruption in case of system "
     500             :                "crash.\n",
     501             :                bdevname(bh->b_bdev, b), (unsigned long long)bh->b_blocknr);
     502           0 : }
     503             : 
     504             : /*
     505             :  * If the buffer is already part of the current transaction, then there
     506             :  * is nothing we need to do.  If it is already part of a prior
     507             :  * transaction which we are still committing to disk, then we need to
     508             :  * make sure that we do not overwrite the old copy: we do copy-out to
     509             :  * preserve the copy going to disk.  We also account the buffer against
     510             :  * the handle's metadata buffer credits (unless the buffer is already
     511             :  * part of the transaction, that is).
     512             :  *
     513             :  */
     514             : static int
     515             : do_get_write_access(handle_t *handle, struct journal_head *jh,
     516             :                         int force_copy)
     517           0 : {
     518           0 :         struct buffer_head *bh;
     519           0 :         transaction_t *transaction;
     520           0 :         journal_t *journal;
     521           0 :         int error;
     522           0 :         char *frozen_buffer = NULL;
     523           0 :         int need_copy = 0;
     524           0 : 
     525           0 :         if (is_handle_aborted(handle))
     526           0 :                 return -EROFS;
     527           0 : 
     528           0 :         transaction = handle->h_transaction;
     529           0 :         journal = transaction->t_journal;
     530           0 : 
     531           0 :         jbd_debug(5, "buffer_head %p, force_copy %d\n", jh, force_copy);
     532           0 : 
     533           0 :         JBUFFER_TRACE(jh, "entry");
     534           0 : repeat:
     535           0 :         bh = jh2bh(jh);
     536           0 : 
     537           0 :         /* @@@ Need to check for errors here at some point. */
     538           0 : 
     539           0 :         lock_buffer(bh);
     540           0 :         jbd_lock_bh_state(bh);
     541           0 : 
     542           0 :         /* We now hold the buffer lock so it is safe to query the buffer
     543           0 :          * state.  Is the buffer dirty?
     544           0 :          *
     545           0 :          * If so, there are two possibilities.  The buffer may be
     546           0 :          * non-journaled, and undergoing a quite legitimate writeback.
     547           0 :          * Otherwise, it is journaled, and we don't expect dirty buffers
     548           0 :          * in that state (the buffers should be marked JBD_Dirty
     549             :          * instead.)  So either the IO is being done under our own
     550             :          * control and this is a bug, or it's a third party IO such as
     551             :          * dump(8) (which may leave the buffer scheduled for read ---
     552             :          * ie. locked but not dirty) or tune2fs (which may actually have
     553             :          * the buffer dirtied, ugh.)  */
     554             : 
     555           0 :         if (buffer_dirty(bh)) {
     556             :                 /*
     557             :                  * First question: is this buffer already part of the current
     558             :                  * transaction or the existing committing transaction?
     559             :                  */
     560           0 :                 if (jh->b_transaction) {
     561           0 :                         J_ASSERT_JH(jh,
     562             :                                 jh->b_transaction == transaction ||
     563             :                                 jh->b_transaction ==
     564             :                                         journal->j_committing_transaction);
     565           0 :                         if (jh->b_next_transaction)
     566           0 :                                 J_ASSERT_JH(jh, jh->b_next_transaction ==
     567             :                                                         transaction);
     568           0 :                         warn_dirty_buffer(bh);
     569             :                 }
     570             :                 /*
     571             :                  * In any case we need to clean the dirty flag and we must
     572             :                  * do it under the buffer lock to be sure we don't race
     573             :                  * with running write-out.
     574             :                  */
     575             :                 JBUFFER_TRACE(jh, "Journalling dirty buffer");
     576           0 :                 clear_buffer_dirty(bh);
     577           0 :                 set_buffer_jbddirty(bh);
     578             :         }
     579             : 
     580           0 :         unlock_buffer(bh);
     581             : 
     582           0 :         error = -EROFS;
     583           0 :         if (is_handle_aborted(handle)) {
     584           0 :                 jbd_unlock_bh_state(bh);
     585           0 :                 goto out;
     586             :         }
     587           0 :         error = 0;
     588             : 
     589             :         /*
     590             :          * The buffer is already part of this transaction if b_transaction or
     591             :          * b_next_transaction points to it
     592             :          */
     593           0 :         if (jh->b_transaction == transaction ||
     594             :             jh->b_next_transaction == transaction)
     595           0 :                 goto done;
     596             : 
     597             :         /*
     598             :          * this is the first time this transaction is touching this buffer,
     599             :          * reset the modified flag
     600             :          */
     601           0 :         jh->b_modified = 0;
     602             : 
     603             :         /*
     604             :          * If there is already a copy-out version of this buffer, then we don't
     605             :          * need to make another one
     606             :          */
     607           0 :         if (jh->b_frozen_data) {
     608             :                 JBUFFER_TRACE(jh, "has frozen data");
     609           0 :                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
     610           0 :                 jh->b_next_transaction = transaction;
     611           0 :                 goto done;
     612             :         }
     613             : 
     614             :         /* Is there data here we need to preserve? */
     615             : 
     616           0 :         if (jh->b_transaction && jh->b_transaction != transaction) {
     617             :                 JBUFFER_TRACE(jh, "owned by older transaction");
     618           0 :                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
     619           0 :                 J_ASSERT_JH(jh, jh->b_transaction ==
     620             :                                         journal->j_committing_transaction);
     621             : 
     622             :                 /* There is one case we have to be very careful about.
     623             :                  * If the committing transaction is currently writing
     624             :                  * this buffer out to disk and has NOT made a copy-out,
     625             :                  * then we cannot modify the buffer contents at all
     626             :                  * right now.  The essence of copy-out is that it is the
     627             :                  * extra copy, not the primary copy, which gets
     628             :                  * journaled.  If the primary copy is already going to
     629             :                  * disk then we cannot do copy-out here. */
     630             : 
     631           0 :                 if (jh->b_jlist == BJ_Shadow) {
     632           0 :                         DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
     633             :                         wait_queue_head_t *wqh;
     634             : 
     635           0 :                         wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);
     636             : 
     637             :                         JBUFFER_TRACE(jh, "on shadow: sleep");
     638           0 :                         jbd_unlock_bh_state(bh);
     639             :                         /* commit wakes up all shadow buffers after IO */
     640           0 :                         for ( ; ; ) {
     641           0 :                                 prepare_to_wait(wqh, &wait.wait,
     642             :                                                 TASK_UNINTERRUPTIBLE);
     643           0 :                                 if (jh->b_jlist != BJ_Shadow)
     644           0 :                                         break;
     645           0 :                                 schedule();
     646           0 :                         }
     647           0 :                         finish_wait(wqh, &wait.wait);
     648           0 :                         goto repeat;
     649             :                 }
     650             : 
     651             :                 /* Only do the copy if the currently-owning transaction
     652             :                  * still needs it.  If it is on the Forget list, the
     653             :                  * committing transaction is past that stage.  The
     654             :                  * buffer had better remain locked during the kmalloc,
     655             :                  * but that should be true --- we hold the journal lock
     656             :                  * still and the buffer is already on the BUF_JOURNAL
     657             :                  * list so won't be flushed.
     658             :                  *
     659             :                  * Subtle point, though: if this is a get_undo_access,
     660             :                  * then we will be relying on the frozen_data to contain
     661             :                  * the new value of the committed_data record after the
     662             :                  * transaction, so we HAVE to force the frozen_data copy
     663             :                  * in that case. */
     664             : 
     665           0 :                 if (jh->b_jlist != BJ_Forget || force_copy) {
     666             :                         JBUFFER_TRACE(jh, "generate frozen data");
     667           0 :                         if (!frozen_buffer) {
     668             :                                 JBUFFER_TRACE(jh, "allocate memory for buffer");
     669           0 :                                 jbd_unlock_bh_state(bh);
     670           0 :                                 frozen_buffer =
     671             :                                         jbd_alloc(jh2bh(jh)->b_size,
     672             :                                                          GFP_NOFS);
     673           0 :                                 if (!frozen_buffer) {
     674           0 :                                         printk(KERN_EMERG
     675             :                                                "%s: OOM for frozen_buffer\n",
     676             :                                                __func__);
     677             :                                         JBUFFER_TRACE(jh, "oom!");
     678           0 :                                         error = -ENOMEM;
     679           0 :                                         jbd_lock_bh_state(bh);
     680           0 :                                         goto done;
     681             :                                 }
     682           0 :                                 goto repeat;
     683             :                         }
     684           0 :                         jh->b_frozen_data = frozen_buffer;
     685           0 :                         frozen_buffer = NULL;
     686           0 :                         need_copy = 1;
     687             :                 }
     688           0 :                 jh->b_next_transaction = transaction;
     689             :         }
     690             : 
     691             : 
     692             :         /*
     693             :          * Finally, if the buffer is not journaled right now, we need to make
     694             :          * sure it doesn't get written to disk before the caller actually
     695             :          * commits the new data
     696             :          */
     697           0 :         if (!jh->b_transaction) {
     698             :                 JBUFFER_TRACE(jh, "no transaction");
     699           0 :                 J_ASSERT_JH(jh, !jh->b_next_transaction);
     700           0 :                 jh->b_transaction = transaction;
     701             :                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
     702           0 :                 spin_lock(&journal->j_list_lock);
     703           0 :                 __journal_file_buffer(jh, transaction, BJ_Reserved);
     704           0 :                 spin_unlock(&journal->j_list_lock);
     705             :         }
     706             : 
     707             : done:
     708           0 :         if (need_copy) {
     709           0 :                 struct page *page;
     710             :                 int offset;
     711             :                 char *source;
     712             : 
     713           0 :                 J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
     714             :                             "Possible IO failure.\n");
     715           0 :                 page = jh2bh(jh)->b_page;
     716           0 :                 offset = ((unsigned long) jh2bh(jh)->b_data) & ~PAGE_MASK;
     717           0 :                 source = kmap_atomic(page, KM_USER0);
     718           0 :                 memcpy(jh->b_frozen_data, source+offset, jh2bh(jh)->b_size);
     719           0 :                 kunmap_atomic(source, KM_USER0);
     720             :         }
     721           0 :         jbd_unlock_bh_state(bh);
     722             : 
     723             :         /*
     724             :          * If we are about to journal a buffer, then any revoke pending on it is
     725             :          * no longer valid
     726             :          */
     727           0 :         journal_cancel_revoke(handle, jh);
     728             : 
     729           0 : out:
     730           0 :         if (unlikely(frozen_buffer))    /* It's usually NULL */
     731           0 :                 jbd_free(frozen_buffer, bh->b_size);
     732             : 
     733             :         JBUFFER_TRACE(jh, "exit");
     734           0 :         return error;
     735             : }
     736             : 
     737             : /**
     738             :  * int journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
     739             :  * @handle: transaction to add buffer modifications to
     740             :  * @bh:     bh to be used for metadata writes
     741             :  *
     742             :  * Returns an error code or 0 on success.
     743             :  *
     744             :  * In full data journalling mode the buffer may be of type BJ_AsyncData,
     745             :  * because we're write()ing a buffer which is also part of a shared mapping.
     746             :  */
     747             : 
     748             : int journal_get_write_access(handle_t *handle, struct buffer_head *bh)
     749             : {
     750           0 :         struct journal_head *jh = journal_add_journal_head(bh);
     751           0 :         int rc;
     752           0 : 
     753             :         /* We do not want to get caught playing with fields which the
     754             :          * log thread also manipulates.  Make sure that the buffer
     755             :          * completes any outstanding IO before proceeding. */
     756           0 :         rc = do_get_write_access(handle, jh, 0);
     757           0 :         journal_put_journal_head(jh);
     758           0 :         return rc;
     759             : }
     760             : 
     761             : 
     762             : /*
     763             :  * When the user wants to journal a newly created buffer_head
     764             :  * (ie. getblk() returned a new buffer and we are going to populate it
     765             :  * manually rather than reading off disk), then we need to keep the
     766             :  * buffer_head locked until it has been completely filled with new
     767             :  * data.  In this case, we should be able to make the assertion that
     768             :  * the bh is not already part of an existing transaction.
     769             :  *
     770             :  * The buffer should already be locked by the caller by this point.
     771             :  * There is no lock ranking violation: it was a newly created,
     772             :  * unlocked buffer beforehand. */
     773             : 
     774             : /**
     775             :  * int journal_get_create_access () - notify intent to use newly created bh
     776             :  * @handle: transaction to new buffer to
     777             :  * @bh: new buffer.
     778             :  *
     779             :  * Call this if you create a new bh.
     780             :  */
     781             : int journal_get_create_access(handle_t *handle, struct buffer_head *bh)
     782             : {
     783           0 :         transaction_t *transaction = handle->h_transaction;
     784           0 :         journal_t *journal = transaction->t_journal;
     785           0 :         struct journal_head *jh = journal_add_journal_head(bh);
     786           0 :         int err;
     787           0 : 
     788           0 :         jbd_debug(5, "journal_head %p\n", jh);
     789           0 :         err = -EROFS;
     790           0 :         if (is_handle_aborted(handle))
     791           0 :                 goto out;
     792           0 :         err = 0;
     793           0 : 
     794           0 :         JBUFFER_TRACE(jh, "entry");
     795           0 :         /*
     796           0 :          * The buffer may already belong to this transaction due to pre-zeroing
     797           0 :          * in the filesystem's new_block code.  It may also be on the previous,
     798           0 :          * committing transaction's lists, but it HAS to be in Forget state in
     799           0 :          * that case: the transaction must have deleted the buffer for it to be
     800             :          * reused here.
     801             :          */
     802           0 :         jbd_lock_bh_state(bh);
     803           0 :         spin_lock(&journal->j_list_lock);
     804           0 :         J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
     805             :                 jh->b_transaction == NULL ||
     806             :                 (jh->b_transaction == journal->j_committing_transaction &&
     807             :                           jh->b_jlist == BJ_Forget)));
     808             : 
     809           0 :         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
     810           0 :         J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
     811             : 
     812           0 :         if (jh->b_transaction == NULL) {
     813             :                 /*
     814             :                  * Previous journal_forget() could have left the buffer
     815             :                  * with jbddirty bit set because it was being committed. When
     816             :                  * the commit finished, we've filed the buffer for
     817             :                  * checkpointing and marked it dirty. Now we are reallocating
     818             :                  * the buffer so the transaction freeing it must have
     819             :                  * committed and so it's safe to clear the dirty bit.
     820             :                  */
     821           0 :                 clear_buffer_dirty(jh2bh(jh));
     822           0 :                 jh->b_transaction = transaction;
     823             : 
     824             :                 /* first access by this transaction */
     825           0 :                 jh->b_modified = 0;
     826             : 
     827             :                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
     828           0 :                 __journal_file_buffer(jh, transaction, BJ_Reserved);
     829           0 :         } else if (jh->b_transaction == journal->j_committing_transaction) {
     830             :                 /* first access by this transaction */
     831           0 :                 jh->b_modified = 0;
     832             : 
     833             :                 JBUFFER_TRACE(jh, "set next transaction");
     834           0 :                 jh->b_next_transaction = transaction;
     835             :         }
     836           0 :         spin_unlock(&journal->j_list_lock);
     837           0 :         jbd_unlock_bh_state(bh);
     838             : 
     839             :         /*
     840             :          * akpm: I added this.  ext3_alloc_branch can pick up new indirect
     841             :          * blocks which contain freed but then revoked metadata.  We need
     842             :          * to cancel the revoke in case we end up freeing it yet again
     843             :          * and the reallocating as data - this would cause a second revoke,
     844             :          * which hits an assertion error.
     845             :          */
     846             :         JBUFFER_TRACE(jh, "cancelling revoke");
     847           0 :         journal_cancel_revoke(handle, jh);
     848           0 :         journal_put_journal_head(jh);
     849             : out:
     850           0 :         return err;
     851             : }
     852             : 
     853             : /**
     854             :  * int journal_get_undo_access() - Notify intent to modify metadata with non-rewindable consequences
     855             :  * @handle: transaction
     856             :  * @bh: buffer to undo
     857             :  *
     858             :  * Sometimes there is a need to distinguish between metadata which has
     859             :  * been committed to disk and that which has not.  The ext3fs code uses
     860             :  * this for freeing and allocating space, we have to make sure that we
     861             :  * do not reuse freed space until the deallocation has been committed,
     862             :  * since if we overwrote that space we would make the delete
     863             :  * un-rewindable in case of a crash.
     864             :  *
     865             :  * To deal with that, journal_get_undo_access requests write access to a
     866             :  * buffer for parts of non-rewindable operations such as delete
     867             :  * operations on the bitmaps.  The journaling code must keep a copy of
     868             :  * the buffer's contents prior to the undo_access call until such time
     869             :  * as we know that the buffer has definitely been committed to disk.
     870             :  *
     871             :  * We never need to know which transaction the committed data is part
     872             :  * of, buffers touched here are guaranteed to be dirtied later and so
     873             :  * will be committed to a new transaction in due course, at which point
     874             :  * we can discard the old committed data pointer.
     875             :  *
     876             :  * Returns error number or 0 on success.
     877             :  */
     878             : int journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
     879             : {
     880           0 :         int err;
     881           0 :         struct journal_head *jh = journal_add_journal_head(bh);
     882           0 :         char *committed_data = NULL;
     883           0 : 
     884           0 :         JBUFFER_TRACE(jh, "entry");
     885           0 : 
     886           0 :         /*
     887             :          * Do this first --- it can drop the journal lock, so we want to
     888             :          * make sure that obtaining the committed_data is done
     889             :          * atomically wrt. completion of any outstanding commits.
     890             :          */
     891           0 :         err = do_get_write_access(handle, jh, 1);
     892           0 :         if (err)
     893           0 :                 goto out;
     894             : 
     895             : repeat:
     896           0 :         if (!jh->b_committed_data) {
     897           0 :                 committed_data = jbd_alloc(jh2bh(jh)->b_size, GFP_NOFS);
     898           0 :                 if (!committed_data) {
     899           0 :                         printk(KERN_EMERG "%s: No memory for committed data\n",
     900             :                                 __func__);
     901           0 :                         err = -ENOMEM;
     902           0 :                         goto out;
     903             :                 }
     904             :         }
     905             : 
     906           0 :         jbd_lock_bh_state(bh);
     907           0 :         if (!jh->b_committed_data) {
     908             :                 /* Copy out the current buffer contents into the
     909             :                  * preserved, committed copy. */
     910             :                 JBUFFER_TRACE(jh, "generate b_committed data");
     911           0 :                 if (!committed_data) {
     912           0 :                         jbd_unlock_bh_state(bh);
     913           0 :                         goto repeat;
     914             :                 }
     915             : 
     916           0 :                 jh->b_committed_data = committed_data;
     917           0 :                 committed_data = NULL;
     918           0 :                 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
     919             :         }
     920           0 :         jbd_unlock_bh_state(bh);
     921             : out:
     922           0 :         journal_put_journal_head(jh);
     923           0 :         if (unlikely(committed_data))
     924           0 :                 jbd_free(committed_data, bh->b_size);
     925           0 :         return err;
     926             : }
     927             : 
     928             : /**
     929             :  * int journal_dirty_data() - mark a buffer as containing dirty data to be flushed
     930             :  * @handle: transaction
     931             :  * @bh: bufferhead to mark
     932             :  *
     933             :  * Description:
     934             :  * Mark a buffer as containing dirty data which needs to be flushed before
     935             :  * we can commit the current transaction.
     936             :  *
     937             :  * The buffer is placed on the transaction's data list and is marked as
     938             :  * belonging to the transaction.
     939             :  *
     940             :  * Returns error number or 0 on success.
     941             :  *
     942             :  * journal_dirty_data() can be called via page_launder->ext3_writepage
     943             :  * by kswapd.
     944             :  */
     945             : int journal_dirty_data(handle_t *handle, struct buffer_head *bh)
     946             : {
     947           0 :         journal_t *journal = handle->h_transaction->t_journal;
     948           0 :         int need_brelse = 0;
     949           0 :         struct journal_head *jh;
     950           0 :         int ret = 0;
     951           0 : 
     952           0 :         if (is_handle_aborted(handle))
     953           0 :                 return ret;
     954           0 : 
     955           0 :         jh = journal_add_journal_head(bh);
     956           0 :         JBUFFER_TRACE(jh, "entry");
     957           0 : 
     958           0 :         /*
     959             :          * The buffer could *already* be dirty.  Writeout can start
     960             :          * at any time.
     961             :          */
     962             :         jbd_debug(4, "jh: %p, tid:%d\n", jh, handle->h_transaction->t_tid);
     963             : 
     964             :         /*
     965             :          * What if the buffer is already part of a running transaction?
     966             :          *
     967             :          * There are two cases:
     968             :          * 1) It is part of the current running transaction.  Refile it,
     969             :          *    just in case we have allocated it as metadata, deallocated
     970             :          *    it, then reallocated it as data.
     971             :          * 2) It is part of the previous, still-committing transaction.
     972             :          *    If all we want to do is to guarantee that the buffer will be
     973             :          *    written to disk before this new transaction commits, then
     974             :          *    being sure that the *previous* transaction has this same
     975             :          *    property is sufficient for us!  Just leave it on its old
     976             :          *    transaction.
     977             :          *
     978             :          * In case (2), the buffer must not already exist as metadata
     979             :          * --- that would violate write ordering (a transaction is free
     980             :          * to write its data at any point, even before the previous
     981             :          * committing transaction has committed).  The caller must
     982             :          * never, ever allow this to happen: there's nothing we can do
     983             :          * about it in this layer.
     984             :          */
     985           0 :         jbd_lock_bh_state(bh);
     986           0 :         spin_lock(&journal->j_list_lock);
     987             : 
     988             :         /* Now that we have bh_state locked, are we really still mapped? */
     989           0 :         if (!buffer_mapped(bh)) {
     990             :                 JBUFFER_TRACE(jh, "unmapped buffer, bailing out");
     991           0 :                 goto no_journal;
     992             :         }
     993             : 
     994           0 :         if (jh->b_transaction) {
     995             :                 JBUFFER_TRACE(jh, "has transaction");
     996           0 :                 if (jh->b_transaction != handle->h_transaction) {
     997             :                         JBUFFER_TRACE(jh, "belongs to older transaction");
     998           0 :                         J_ASSERT_JH(jh, jh->b_transaction ==
     999             :                                         journal->j_committing_transaction);
    1000             : 
    1001             :                         /* @@@ IS THIS TRUE  ? */
    1002             :                         /*
    1003             :                          * Not any more.  Scenario: someone does a write()
    1004             :                          * in data=journal mode.  The buffer's transaction has
    1005             :                          * moved into commit.  Then someone does another
    1006             :                          * write() to the file.  We do the frozen data copyout
    1007             :                          * and set b_next_transaction to point to j_running_t.
    1008             :                          * And while we're in that state, someone does a
    1009             :                          * writepage() in an attempt to pageout the same area
    1010             :                          * of the file via a shared mapping.  At present that
    1011             :                          * calls journal_dirty_data(), and we get right here.
    1012             :                          * It may be too late to journal the data.  Simply
    1013             :                          * falling through to the next test will suffice: the
    1014             :                          * data will be dirty and wil be checkpointed.  The
    1015             :                          * ordering comments in the next comment block still
    1016             :                          * apply.
    1017             :                          */
    1018             :                         //J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
    1019             : 
    1020             :                         /*
    1021             :                          * If we're journalling data, and this buffer was
    1022             :                          * subject to a write(), it could be metadata, forget
    1023             :                          * or shadow against the committing transaction.  Now,
    1024             :                          * someone has dirtied the same darn page via a mapping
    1025             :                          * and it is being writepage()'d.
    1026             :                          * We *could* just steal the page from commit, with some
    1027             :                          * fancy locking there.  Instead, we just skip it -
    1028             :                          * don't tie the page's buffers to the new transaction
    1029             :                          * at all.
    1030             :                          * Implication: if we crash before the writepage() data
    1031             :                          * is written into the filesystem, recovery will replay
    1032             :                          * the write() data.
    1033             :                          */
    1034           0 :                         if (jh->b_jlist != BJ_None &&
    1035             :                                         jh->b_jlist != BJ_SyncData &&
    1036             :                                         jh->b_jlist != BJ_Locked) {
    1037             :                                 JBUFFER_TRACE(jh, "Not stealing");
    1038           0 :                                 goto no_journal;
    1039             :                         }
    1040             : 
    1041             :                         /*
    1042             :                          * This buffer may be undergoing writeout in commit.  We
    1043             :                          * can't return from here and let the caller dirty it
    1044             :                          * again because that can cause the write-out loop in
    1045             :                          * commit to never terminate.
    1046             :                          */
    1047           0 :                         if (buffer_dirty(bh)) {
    1048           0 :                                 get_bh(bh);
    1049           0 :                                 spin_unlock(&journal->j_list_lock);
    1050           0 :                                 jbd_unlock_bh_state(bh);
    1051           0 :                                 need_brelse = 1;
    1052           0 :                                 sync_dirty_buffer(bh);
    1053           0 :                                 jbd_lock_bh_state(bh);
    1054           0 :                                 spin_lock(&journal->j_list_lock);
    1055             :                                 /* Since we dropped the lock... */
    1056           0 :                                 if (!buffer_mapped(bh)) {
    1057             :                                         JBUFFER_TRACE(jh, "buffer got unmapped");
    1058           0 :                                         goto no_journal;
    1059             :                                 }
    1060             :                                 /* The buffer may become locked again at any
    1061             :                                    time if it is redirtied */
    1062             :                         }
    1063             : 
    1064             :                         /*
    1065             :                          * We cannot remove the buffer with io error from the
    1066             :                          * committing transaction, because otherwise it would
    1067             :                          * miss the error and the commit would not abort.
    1068             :                          */
    1069           0 :                         if (unlikely(!buffer_uptodate(bh))) {
    1070           0 :                                 ret = -EIO;
    1071           0 :                                 goto no_journal;
    1072             :                         }
    1073             : 
    1074           0 :                         if (jh->b_transaction != NULL) {
    1075             :                                 JBUFFER_TRACE(jh, "unfile from commit");
    1076           0 :                                 __journal_temp_unlink_buffer(jh);
    1077             :                                 /* It still points to the committing
    1078             :                                  * transaction; move it to this one so
    1079             :                                  * that the refile assert checks are
    1080             :                                  * happy. */
    1081           0 :                                 jh->b_transaction = handle->h_transaction;
    1082             :                         }
    1083             :                         /* The buffer will be refiled below */
    1084             : 
    1085             :                 }
    1086             :                 /*
    1087             :                  * Special case --- the buffer might actually have been
    1088             :                  * allocated and then immediately deallocated in the previous,
    1089             :                  * committing transaction, so might still be left on that
    1090             :                  * transaction's metadata lists.
    1091             :                  */
    1092           0 :                 if (jh->b_jlist != BJ_SyncData && jh->b_jlist != BJ_Locked) {
    1093             :                         JBUFFER_TRACE(jh, "not on correct data list: unfile");
    1094           0 :                         J_ASSERT_JH(jh, jh->b_jlist != BJ_Shadow);
    1095           0 :                         __journal_temp_unlink_buffer(jh);
    1096           0 :                         jh->b_transaction = handle->h_transaction;
    1097             :                         JBUFFER_TRACE(jh, "file as data");
    1098           0 :                         __journal_file_buffer(jh, handle->h_transaction,
    1099             :                                                 BJ_SyncData);
    1100             :                 }
    1101             :         } else {
    1102             :                 JBUFFER_TRACE(jh, "not on a transaction");
    1103           0 :                 __journal_file_buffer(jh, handle->h_transaction, BJ_SyncData);
    1104             :         }
    1105             : no_journal:
    1106           0 :         spin_unlock(&journal->j_list_lock);
    1107           0 :         jbd_unlock_bh_state(bh);
    1108           0 :         if (need_brelse) {
    1109             :                 BUFFER_TRACE(bh, "brelse");
    1110           0 :                 __brelse(bh);
    1111             :         }
    1112             :         JBUFFER_TRACE(jh, "exit");
    1113           0 :         journal_put_journal_head(jh);
    1114           0 :         return ret;
    1115             : }
    1116             : 
    1117             : /**
    1118             :  * int journal_dirty_metadata() - mark a buffer as containing dirty metadata
    1119             :  * @handle: transaction to add buffer to.
    1120             :  * @bh: buffer to mark
    1121             :  *
    1122             :  * Mark dirty metadata which needs to be journaled as part of the current
    1123             :  * transaction.
    1124             :  *
    1125             :  * The buffer is placed on the transaction's metadata list and is marked
    1126             :  * as belonging to the transaction.
    1127             :  *
    1128             :  * Returns error number or 0 on success.
    1129             :  *
    1130             :  * Special care needs to be taken if the buffer already belongs to the
    1131             :  * current committing transaction (in which case we should have frozen
    1132             :  * data present for that commit).  In that case, we don't relink the
    1133             :  * buffer: that only gets done when the old transaction finally
    1134             :  * completes its commit.
    1135             :  */
    1136             : int journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
    1137             : {
    1138           0 :         transaction_t *transaction = handle->h_transaction;
    1139           0 :         journal_t *journal = transaction->t_journal;
    1140           0 :         struct journal_head *jh = bh2jh(bh);
    1141           0 : 
    1142           0 :         jbd_debug(5, "journal_head %p\n", jh);
    1143           0 :         JBUFFER_TRACE(jh, "entry");
    1144           0 :         if (is_handle_aborted(handle))
    1145           0 :                 goto out;
    1146           0 : 
    1147           0 :         jbd_lock_bh_state(bh);
    1148             : 
    1149           0 :         if (jh->b_modified == 0) {
    1150             :                 /*
    1151             :                  * This buffer's got modified and becoming part
    1152             :                  * of the transaction. This needs to be done
    1153             :                  * once a transaction -bzzz
    1154             :                  */
    1155           0 :                 jh->b_modified = 1;
    1156           0 :                 J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
    1157           0 :                 handle->h_buffer_credits--;
    1158             :         }
    1159             : 
    1160             :         /*
    1161             :          * fastpath, to avoid expensive locking.  If this buffer is already
    1162             :          * on the running transaction's metadata list there is nothing to do.
    1163             :          * Nobody can take it off again because there is a handle open.
    1164             :          * I _think_ we're OK here with SMP barriers - a mistaken decision will
    1165             :          * result in this test being false, so we go in and take the locks.
    1166             :          */
    1167           0 :         if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
    1168             :                 JBUFFER_TRACE(jh, "fastpath");
    1169           0 :                 J_ASSERT_JH(jh, jh->b_transaction ==
    1170             :                                         journal->j_running_transaction);
    1171           0 :                 goto out_unlock_bh;
    1172             :         }
    1173             : 
    1174           0 :         set_buffer_jbddirty(bh);
    1175             : 
    1176             :         /*
    1177             :          * Metadata already on the current transaction list doesn't
    1178             :          * need to be filed.  Metadata on another transaction's list must
    1179             :          * be committing, and will be refiled once the commit completes:
    1180             :          * leave it alone for now.
    1181             :          */
    1182           0 :         if (jh->b_transaction != transaction) {
    1183             :                 JBUFFER_TRACE(jh, "already on other transaction");
    1184           0 :                 J_ASSERT_JH(jh, jh->b_transaction ==
    1185             :                                         journal->j_committing_transaction);
    1186           0 :                 J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
    1187             :                 /* And this case is illegal: we can't reuse another
    1188             :                  * transaction's data buffer, ever. */
    1189           0 :                 goto out_unlock_bh;
    1190             :         }
    1191             : 
    1192             :         /* That test should have eliminated the following case: */
    1193           0 :         J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
    1194             : 
    1195             :         JBUFFER_TRACE(jh, "file as BJ_Metadata");
    1196           0 :         spin_lock(&journal->j_list_lock);
    1197           0 :         __journal_file_buffer(jh, handle->h_transaction, BJ_Metadata);
    1198           0 :         spin_unlock(&journal->j_list_lock);
    1199             : out_unlock_bh:
    1200           0 :         jbd_unlock_bh_state(bh);
    1201             : out:
    1202           0 :         JBUFFER_TRACE(jh, "exit");
    1203           0 :         return 0;
    1204             : }
    1205             : 
    1206             : /*
    1207             :  * journal_release_buffer: undo a get_write_access without any buffer
    1208             :  * updates, if the update decided in the end that it didn't need access.
    1209             :  *
    1210             :  */
    1211             : void
    1212             : journal_release_buffer(handle_t *handle, struct buffer_head *bh)
    1213             : {
    1214           0 :         BUFFER_TRACE(bh, "entry");
    1215             : }
    1216             : 
    1217             : /**
    1218             :  * void journal_forget() - bforget() for potentially-journaled buffers.
    1219             :  * @handle: transaction handle
    1220             :  * @bh:     bh to 'forget'
    1221             :  *
    1222             :  * We can only do the bforget if there are no commits pending against the
    1223             :  * buffer.  If the buffer is dirty in the current running transaction we
    1224             :  * can safely unlink it.
    1225             :  *
    1226             :  * bh may not be a journalled buffer at all - it may be a non-JBD
    1227             :  * buffer which came off the hashtable.  Check for this.
    1228             :  *
    1229             :  * Decrements bh->b_count by one.
    1230             :  *
    1231             :  * Allow this call even if the handle has aborted --- it may be part of
    1232             :  * the caller's cleanup after an abort.
    1233             :  */
    1234             : int journal_forget (handle_t *handle, struct buffer_head *bh)
    1235             : {
    1236           0 :         transaction_t *transaction = handle->h_transaction;
    1237           0 :         journal_t *journal = transaction->t_journal;
    1238           0 :         struct journal_head *jh;
    1239           0 :         int drop_reserve = 0;
    1240           0 :         int err = 0;
    1241           0 :         int was_modified = 0;
    1242           0 : 
    1243           0 :         BUFFER_TRACE(bh, "entry");
    1244           0 : 
    1245           0 :         jbd_lock_bh_state(bh);
    1246           0 :         spin_lock(&journal->j_list_lock);
    1247           0 : 
    1248           0 :         if (!buffer_jbd(bh))
    1249           0 :                 goto not_jbd;
    1250           0 :         jh = bh2jh(bh);
    1251             : 
    1252             :         /* Critical error: attempting to delete a bitmap buffer, maybe?
    1253             :          * Don't do any jbd operations, and return an error. */
    1254           0 :         if (!J_EXPECT_JH(jh, !jh->b_committed_data,
    1255             :                          "inconsistent data on disk")) {
    1256           0 :                 err = -EIO;
    1257           0 :                 goto not_jbd;
    1258             :         }
    1259             : 
    1260             :         /* keep track of wether or not this transaction modified us */
    1261           0 :         was_modified = jh->b_modified;
    1262             : 
    1263             :         /*
    1264             :          * The buffer's going from the transaction, we must drop
    1265             :          * all references -bzzz
    1266             :          */
    1267           0 :         jh->b_modified = 0;
    1268             : 
    1269           0 :         if (jh->b_transaction == handle->h_transaction) {
    1270           0 :                 J_ASSERT_JH(jh, !jh->b_frozen_data);
    1271             : 
    1272             :                 /* If we are forgetting a buffer which is already part
    1273             :                  * of this transaction, then we can just drop it from
    1274             :                  * the transaction immediately. */
    1275           0 :                 clear_buffer_dirty(bh);
    1276           0 :                 clear_buffer_jbddirty(bh);
    1277             : 
    1278             :                 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
    1279             : 
    1280             :                 /*
    1281             :                  * we only want to drop a reference if this transaction
    1282             :                  * modified the buffer
    1283             :                  */
    1284           0 :                 if (was_modified)
    1285           0 :                         drop_reserve = 1;
    1286             : 
    1287             :                 /*
    1288             :                  * We are no longer going to journal this buffer.
    1289             :                  * However, the commit of this transaction is still
    1290             :                  * important to the buffer: the delete that we are now
    1291             :                  * processing might obsolete an old log entry, so by
    1292             :                  * committing, we can satisfy the buffer's checkpoint.
    1293             :                  *
    1294             :                  * So, if we have a checkpoint on the buffer, we should
    1295             :                  * now refile the buffer on our BJ_Forget list so that
    1296             :                  * we know to remove the checkpoint after we commit.
    1297             :                  */
    1298             : 
    1299           0 :                 if (jh->b_cp_transaction) {
    1300           0 :                         __journal_temp_unlink_buffer(jh);
    1301           0 :                         __journal_file_buffer(jh, transaction, BJ_Forget);
    1302             :                 } else {
    1303           0 :                         __journal_unfile_buffer(jh);
    1304           0 :                         journal_remove_journal_head(bh);
    1305           0 :                         __brelse(bh);
    1306           0 :                         if (!buffer_jbd(bh)) {
    1307           0 :                                 spin_unlock(&journal->j_list_lock);
    1308           0 :                                 jbd_unlock_bh_state(bh);
    1309           0 :                                 __bforget(bh);
    1310           0 :                                 goto drop;
    1311             :                         }
    1312             :                 }
    1313           0 :         } else if (jh->b_transaction) {
    1314           0 :                 J_ASSERT_JH(jh, (jh->b_transaction ==
    1315             :                                  journal->j_committing_transaction));
    1316             :                 /* However, if the buffer is still owned by a prior
    1317             :                  * (committing) transaction, we can't drop it yet... */
    1318             :                 JBUFFER_TRACE(jh, "belongs to older transaction");
    1319             :                 /* ... but we CAN drop it from the new transaction if we
    1320             :                  * have also modified it since the original commit. */
    1321             : 
    1322           0 :                 if (jh->b_next_transaction) {
    1323           0 :                         J_ASSERT(jh->b_next_transaction == transaction);
    1324           0 :                         jh->b_next_transaction = NULL;
    1325             : 
    1326             :                         /*
    1327             :                          * only drop a reference if this transaction modified
    1328             :                          * the buffer
    1329             :                          */
    1330           0 :                         if (was_modified)
    1331           0 :                                 drop_reserve = 1;
    1332             :                 }
    1333             :         }
    1334             : 
    1335             : not_jbd:
    1336           0 :         spin_unlock(&journal->j_list_lock);
    1337           0 :         jbd_unlock_bh_state(bh);
    1338           0 :         __brelse(bh);
    1339             : drop:
    1340           0 :         if (drop_reserve) {
    1341           0 :                 /* no need to reserve log space for this block -bzzz */
    1342           0 :                 handle->h_buffer_credits++;
    1343             :         }
    1344           0 :         return err;
    1345             : }
    1346             : 
    1347             : /**
    1348             :  * int journal_stop() - complete a transaction
    1349             :  * @handle: tranaction to complete.
    1350             :  *
    1351             :  * All done for a particular handle.
    1352             :  *
    1353             :  * There is not much action needed here.  We just return any remaining
    1354             :  * buffer credits to the transaction and remove the handle.  The only
    1355             :  * complication is that we need to start a commit operation if the
    1356             :  * filesystem is marked for synchronous update.
    1357             :  *
    1358             :  * journal_stop itself will not usually return an error, but it may
    1359             :  * do so in unusual circumstances.  In particular, expect it to
    1360             :  * return -EIO if a journal_abort has been executed since the
    1361             :  * transaction began.
    1362             :  */
    1363             : int journal_stop(handle_t *handle)
    1364             : {
    1365           0 :         transaction_t *transaction = handle->h_transaction;
    1366           0 :         journal_t *journal = transaction->t_journal;
    1367           0 :         int err;
    1368           0 :         pid_t pid;
    1369           0 : 
    1370           0 :         J_ASSERT(journal_current_handle() == handle);
    1371           0 : 
    1372           0 :         if (is_handle_aborted(handle))
    1373           0 :                 err = -EIO;
    1374           0 :         else {
    1375           0 :                 J_ASSERT(transaction->t_updates > 0);
    1376           0 :                 err = 0;
    1377           0 :         }
    1378           0 : 
    1379           0 :         if (--handle->h_ref > 0) {
    1380           0 :                 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
    1381           0 :                           handle->h_ref);
    1382           0 :                 return err;
    1383           0 :         }
    1384           0 : 
    1385           0 :         jbd_debug(4, "Handle %p going down\n", handle);
    1386           0 : 
    1387           0 :         /*
    1388           0 :          * Implement synchronous transaction batching.  If the handle
    1389           0 :          * was synchronous, don't force a commit immediately.  Let's
    1390           0 :          * yield and let another thread piggyback onto this transaction.
    1391             :          * Keep doing that while new threads continue to arrive.
    1392             :          * It doesn't cost much - we're about to run a commit and sleep
    1393             :          * on IO anyway.  Speeds up many-threaded, many-dir operations
    1394             :          * by 30x or more...
    1395             :          *
    1396             :          * We try and optimize the sleep time against what the underlying disk
    1397             :          * can do, instead of having a static sleep time.  This is usefull for
    1398             :          * the case where our storage is so fast that it is more optimal to go
    1399             :          * ahead and force a flush and wait for the transaction to be committed
    1400             :          * than it is to wait for an arbitrary amount of time for new writers to
    1401             :          * join the transaction.  We acheive this by measuring how long it takes
    1402             :          * to commit a transaction, and compare it with how long this
    1403             :          * transaction has been running, and if run time < commit time then we
    1404             :          * sleep for the delta and commit.  This greatly helps super fast disks
    1405             :          * that would see slowdowns as more threads started doing fsyncs.
    1406             :          *
    1407             :          * But don't do this if this process was the most recent one to
    1408             :          * perform a synchronous write.  We do this to detect the case where a
    1409             :          * single process is doing a stream of sync writes.  No point in waiting
    1410             :          * for joiners in that case.
    1411             :          */
    1412           0 :         pid = current->pid;
    1413           0 :         if (handle->h_sync && journal->j_last_sync_writer != pid) {
    1414             :                 u64 commit_time, trans_time;
    1415             : 
    1416           0 :                 journal->j_last_sync_writer = pid;
    1417             : 
    1418           0 :                 spin_lock(&journal->j_state_lock);
    1419           0 :                 commit_time = journal->j_average_commit_time;
    1420           0 :                 spin_unlock(&journal->j_state_lock);
    1421             : 
    1422           0 :                 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
    1423             :                                                    transaction->t_start_time));
    1424             : 
    1425           0 :                 commit_time = min_t(u64, commit_time,
    1426             :                                     1000*jiffies_to_usecs(1));
    1427             : 
    1428           0 :                 if (trans_time < commit_time) {
    1429           0 :                         ktime_t expires = ktime_add_ns(ktime_get(),
    1430             :                                                        commit_time);
    1431           0 :                         set_current_state(TASK_UNINTERRUPTIBLE);
    1432           0 :                         schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
    1433             :                 }
    1434             :         }
    1435             : 
    1436           0 :         if (handle->h_sync)
    1437           0 :                 transaction->t_synchronous_commit = 1;
    1438           0 :         current->journal_info = NULL;
    1439           0 :         spin_lock(&journal->j_state_lock);
    1440           0 :         spin_lock(&transaction->t_handle_lock);
    1441           0 :         transaction->t_outstanding_credits -= handle->h_buffer_credits;
    1442           0 :         transaction->t_updates--;
    1443           0 :         if (!transaction->t_updates) {
    1444           0 :                 wake_up(&journal->j_wait_updates);
    1445           0 :                 if (journal->j_barrier_count)
    1446           0 :                         wake_up(&journal->j_wait_transaction_locked);
    1447             :         }
    1448             : 
    1449             :         /*
    1450             :          * If the handle is marked SYNC, we need to set another commit
    1451             :          * going!  We also want to force a commit if the current
    1452             :          * transaction is occupying too much of the log, or if the
    1453             :          * transaction is too old now.
    1454             :          */
    1455             :         if (handle->h_sync ||
    1456             :                         transaction->t_outstanding_credits >
    1457             :                                 journal->j_max_transaction_buffers ||
    1458           0 :                         time_after_eq(jiffies, transaction->t_expires)) {
    1459             :                 /* Do this even for aborted journals: an abort still
    1460             :                  * completes the commit thread, it just doesn't write
    1461             :                  * anything to disk. */
    1462           0 :                 tid_t tid = transaction->t_tid;
    1463             : 
    1464           0 :                 spin_unlock(&transaction->t_handle_lock);
    1465             :                 jbd_debug(2, "transaction too old, requesting commit for "
    1466             :                                         "handle %p\n", handle);
    1467             :                 /* This is non-blocking */
    1468           0 :                 __log_start_commit(journal, transaction->t_tid);
    1469           0 :                 spin_unlock(&journal->j_state_lock);
    1470             : 
    1471             :                 /*
    1472             :                  * Special case: JFS_SYNC synchronous updates require us
    1473             :                  * to wait for the commit to complete.
    1474             :                  */
    1475           0 :                 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
    1476           0 :                         err = log_wait_commit(journal, tid);
    1477             :         } else {
    1478           0 :                 spin_unlock(&transaction->t_handle_lock);
    1479           0 :                 spin_unlock(&journal->j_state_lock);
    1480             :         }
    1481             : 
    1482             :         lock_map_release(&handle->h_lockdep_map);
    1483             : 
    1484           0 :         jbd_free_handle(handle);
    1485           0 :         return err;
    1486             : }
    1487             : 
    1488             : /**
    1489             :  * int journal_force_commit() - force any uncommitted transactions
    1490             :  * @journal: journal to force
    1491             :  *
    1492             :  * For synchronous operations: force any uncommitted transactions
    1493             :  * to disk.  May seem kludgy, but it reuses all the handle batching
    1494             :  * code in a very simple manner.
    1495             :  */
    1496             : int journal_force_commit(journal_t *journal)
    1497             : {
    1498           0 :         handle_t *handle;
    1499           0 :         int ret;
    1500           0 : 
    1501           0 :         handle = journal_start(journal, 1);
    1502           0 :         if (IS_ERR(handle)) {
    1503           0 :                 ret = PTR_ERR(handle);
    1504             :         } else {
    1505           0 :                 handle->h_sync = 1;
    1506           0 :                 ret = journal_stop(handle);
    1507             :         }
    1508           0 :         return ret;
    1509             : }
    1510             : 
    1511             : /*
    1512             :  *
    1513             :  * List management code snippets: various functions for manipulating the
    1514             :  * transaction buffer lists.
    1515             :  *
    1516             :  */
    1517             : 
    1518             : /*
    1519             :  * Append a buffer to a transaction list, given the transaction's list head
    1520             :  * pointer.
    1521             :  *
    1522             :  * j_list_lock is held.
    1523             :  *
    1524             :  * jbd_lock_bh_state(jh2bh(jh)) is held.
    1525             :  */
    1526             : 
    1527             : static inline void
    1528             : __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
    1529             : {
    1530           0 :         if (!*list) {
    1531           0 :                 jh->b_tnext = jh->b_tprev = jh;
    1532           0 :                 *list = jh;
    1533           0 :         } else {
    1534             :                 /* Insert at the tail of the list to preserve order */
    1535           0 :                 struct journal_head *first = *list, *last = first->b_tprev;
    1536           0 :                 jh->b_tprev = last;
    1537           0 :                 jh->b_tnext = first;
    1538           0 :                 last->b_tnext = first->b_tprev = jh;
    1539             :         }
    1540           0 : }
    1541             : 
    1542             : /*
    1543             :  * Remove a buffer from a transaction list, given the transaction's list
    1544             :  * head pointer.
    1545             :  *
    1546             :  * Called with j_list_lock held, and the journal may not be locked.
    1547             :  *
    1548             :  * jbd_lock_bh_state(jh2bh(jh)) is held.
    1549             :  */
    1550             : 
    1551             : static inline void
    1552             : __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
    1553             : {
    1554           0 :         if (*list == jh) {
    1555           0 :                 *list = jh->b_tnext;
    1556           0 :                 if (*list == jh)
    1557           0 :                         *list = NULL;
    1558             :         }
    1559           0 :         jh->b_tprev->b_tnext = jh->b_tnext;
    1560           0 :         jh->b_tnext->b_tprev = jh->b_tprev;
    1561           0 : }
    1562             : 
    1563             : /*
    1564             :  * Remove a buffer from the appropriate transaction list.
    1565             :  *
    1566             :  * Note that this function can *change* the value of
    1567             :  * bh->b_transaction->t_sync_datalist, t_buffers, t_forget,
    1568             :  * t_iobuf_list, t_shadow_list, t_log_list or t_reserved_list.  If the caller
    1569             :  * is holding onto a copy of one of thee pointers, it could go bad.
    1570             :  * Generally the caller needs to re-read the pointer from the transaction_t.
    1571             :  *
    1572             :  * Called under j_list_lock.  The journal may not be locked.
    1573             :  */
    1574             : static void __journal_temp_unlink_buffer(struct journal_head *jh)
    1575             : {
    1576           0 :         struct journal_head **list = NULL;
    1577           0 :         transaction_t *transaction;
    1578           0 :         struct buffer_head *bh = jh2bh(jh);
    1579           0 : 
    1580           0 :         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
    1581           0 :         transaction = jh->b_transaction;
    1582           0 :         if (transaction)
    1583           0 :                 assert_spin_locked(&transaction->t_journal->j_list_lock);
    1584           0 : 
    1585           0 :         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
    1586           0 :         if (jh->b_jlist != BJ_None)
    1587           0 :                 J_ASSERT_JH(jh, transaction != NULL);
    1588             : 
    1589           0 :         switch (jh->b_jlist) {
    1590           0 :         case BJ_None:
    1591           0 :                 return;
    1592           0 :         case BJ_SyncData:
    1593           0 :                 list = &transaction->t_sync_datalist;
    1594           0 :                 break;
    1595           0 :         case BJ_Metadata:
    1596           0 :                 transaction->t_nr_buffers--;
    1597           0 :                 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
    1598           0 :                 list = &transaction->t_buffers;
    1599           0 :                 break;
    1600           0 :         case BJ_Forget:
    1601           0 :                 list = &transaction->t_forget;
    1602           0 :                 break;
    1603           0 :         case BJ_IO:
    1604           0 :                 list = &transaction->t_iobuf_list;
    1605           0 :                 break;
    1606           0 :         case BJ_Shadow:
    1607           0 :                 list = &transaction->t_shadow_list;
    1608           0 :                 break;
    1609           0 :         case BJ_LogCtl:
    1610           0 :                 list = &transaction->t_log_list;
    1611           0 :                 break;
    1612           0 :         case BJ_Reserved:
    1613           0 :                 list = &transaction->t_reserved_list;
    1614           0 :                 break;
    1615           0 :         case BJ_Locked:
    1616           0 :                 list = &transaction->t_locked_list;
    1617           0 :                 break;
    1618           0 :         }
    1619             : 
    1620           0 :         __blist_del_buffer(list, jh);
    1621           0 :         jh->b_jlist = BJ_None;
    1622           0 :         if (test_clear_buffer_jbddirty(bh))
    1623           0 :                 mark_buffer_dirty(bh);  /* Expose it to the VM */
    1624           0 : }
    1625             : 
    1626             : void __journal_unfile_buffer(struct journal_head *jh)
    1627             : {
    1628           0 :         __journal_temp_unlink_buffer(jh);
    1629           0 :         jh->b_transaction = NULL;
    1630           0 : }
    1631             : 
    1632             : void journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
    1633             : {
    1634           0 :         jbd_lock_bh_state(jh2bh(jh));
    1635           0 :         spin_lock(&journal->j_list_lock);
    1636           0 :         __journal_unfile_buffer(jh);
    1637           0 :         spin_unlock(&journal->j_list_lock);
    1638           0 :         jbd_unlock_bh_state(jh2bh(jh));
    1639           0 : }
    1640             : 
    1641             : /*
    1642             :  * Called from journal_try_to_free_buffers().
    1643             :  *
    1644             :  * Called under jbd_lock_bh_state(bh)
    1645             :  */
    1646             : static void
    1647             : __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
    1648             : {
    1649           0 :         struct journal_head *jh;
    1650           0 : 
    1651           0 :         jh = bh2jh(bh);
    1652             : 
    1653           0 :         if (buffer_locked(bh) || buffer_dirty(bh))
    1654           0 :                 goto out;
    1655             : 
    1656           0 :         if (jh->b_next_transaction != NULL)
    1657           0 :                 goto out;
    1658             : 
    1659           0 :         spin_lock(&journal->j_list_lock);
    1660           0 :         if (jh->b_transaction != NULL && jh->b_cp_transaction == NULL) {
    1661           0 :                 if (jh->b_jlist == BJ_SyncData || jh->b_jlist == BJ_Locked) {
    1662             :                         /* A written-back ordered data buffer */
    1663             :                         JBUFFER_TRACE(jh, "release data");
    1664           0 :                         __journal_unfile_buffer(jh);
    1665           0 :                         journal_remove_journal_head(bh);
    1666           0 :                         __brelse(bh);
    1667             :                 }
    1668           0 :         } else if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
    1669             :                 /* written-back checkpointed metadata buffer */
    1670           0 :                 if (jh->b_jlist == BJ_None) {
    1671             :                         JBUFFER_TRACE(jh, "remove from checkpoint list");
    1672           0 :                         __journal_remove_checkpoint(jh);
    1673           0 :                         journal_remove_journal_head(bh);
    1674           0 :                         __brelse(bh);
    1675             :                 }
    1676             :         }
    1677           0 :         spin_unlock(&journal->j_list_lock);
    1678             : out:
    1679           0 :         return;
    1680             : }
    1681             : 
    1682             : /**
    1683             :  * int journal_try_to_free_buffers() - try to free page buffers.
    1684             :  * @journal: journal for operation
    1685             :  * @page: to try and free
    1686             :  * @gfp_mask: we use the mask to detect how hard should we try to release
    1687             :  * buffers. If __GFP_WAIT and __GFP_FS is set, we wait for commit code to
    1688             :  * release the buffers.
    1689             :  *
    1690             :  *
    1691             :  * For all the buffers on this page,
    1692             :  * if they are fully written out ordered data, move them onto BUF_CLEAN
    1693             :  * so try_to_free_buffers() can reap them.
    1694             :  *
    1695             :  * This function returns non-zero if we wish try_to_free_buffers()
    1696             :  * to be called. We do this if the page is releasable by try_to_free_buffers().
    1697             :  * We also do it if the page has locked or dirty buffers and the caller wants
    1698             :  * us to perform sync or async writeout.
    1699             :  *
    1700             :  * This complicates JBD locking somewhat.  We aren't protected by the
    1701             :  * BKL here.  We wish to remove the buffer from its committing or
    1702             :  * running transaction's ->t_datalist via __journal_unfile_buffer.
    1703             :  *
    1704             :  * This may *change* the value of transaction_t->t_datalist, so anyone
    1705             :  * who looks at t_datalist needs to lock against this function.
    1706             :  *
    1707             :  * Even worse, someone may be doing a journal_dirty_data on this
    1708             :  * buffer.  So we need to lock against that.  journal_dirty_data()
    1709             :  * will come out of the lock with the buffer dirty, which makes it
    1710             :  * ineligible for release here.
    1711             :  *
    1712             :  * Who else is affected by this?  hmm...  Really the only contender
    1713             :  * is do_get_write_access() - it could be looking at the buffer while
    1714             :  * journal_try_to_free_buffer() is changing its state.  But that
    1715             :  * cannot happen because we never reallocate freed data as metadata
    1716             :  * while the data is part of a transaction.  Yes?
    1717             :  *
    1718             :  * Return 0 on failure, 1 on success
    1719             :  */
    1720             : int journal_try_to_free_buffers(journal_t *journal,
    1721             :                                 struct page *page, gfp_t gfp_mask)
    1722           0 : {
    1723           0 :         struct buffer_head *head;
    1724           0 :         struct buffer_head *bh;
    1725           0 :         int ret = 0;
    1726           0 : 
    1727           0 :         J_ASSERT(PageLocked(page));
    1728           0 : 
    1729           0 :         head = page_buffers(page);
    1730           0 :         bh = head;
    1731           0 :         do {
    1732             :                 struct journal_head *jh;
    1733             : 
    1734             :                 /*
    1735             :                  * We take our own ref against the journal_head here to avoid
    1736             :                  * having to add tons of locking around each instance of
    1737             :                  * journal_remove_journal_head() and journal_put_journal_head().
    1738             :                  */
    1739           0 :                 jh = journal_grab_journal_head(bh);
    1740           0 :                 if (!jh)
    1741           0 :                         continue;
    1742             : 
    1743           0 :                 jbd_lock_bh_state(bh);
    1744           0 :                 __journal_try_to_free_buffer(journal, bh);
    1745           0 :                 journal_put_journal_head(jh);
    1746           0 :                 jbd_unlock_bh_state(bh);
    1747           0 :                 if (buffer_jbd(bh))
    1748           0 :                         goto busy;
    1749           0 :         } while ((bh = bh->b_this_page) != head);
    1750             : 
    1751           0 :         ret = try_to_free_buffers(page);
    1752           0 : 
    1753           0 : busy:
    1754           0 :         return ret;
    1755             : }
    1756             : 
    1757             : /*
    1758             :  * This buffer is no longer needed.  If it is on an older transaction's
    1759             :  * checkpoint list we need to record it on this transaction's forget list
    1760             :  * to pin this buffer (and hence its checkpointing transaction) down until
    1761             :  * this transaction commits.  If the buffer isn't on a checkpoint list, we
    1762             :  * release it.
    1763             :  * Returns non-zero if JBD no longer has an interest in the buffer.
    1764             :  *
    1765             :  * Called under j_list_lock.
    1766             :  *
    1767             :  * Called under jbd_lock_bh_state(bh).
    1768             :  */
    1769             : static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
    1770             : {
    1771           0 :         int may_free = 1;
    1772           0 :         struct buffer_head *bh = jh2bh(jh);
    1773           0 : 
    1774           0 :         __journal_unfile_buffer(jh);
    1775             : 
    1776           0 :         if (jh->b_cp_transaction) {
    1777             :                 JBUFFER_TRACE(jh, "on running+cp transaction");
    1778             :                 /*
    1779             :                  * We don't want to write the buffer anymore, clear the
    1780             :                  * bit so that we don't confuse checks in
    1781             :                  * __journal_file_buffer
    1782             :                  */
    1783           0 :                 clear_buffer_dirty(bh);
    1784           0 :                 __journal_file_buffer(jh, transaction, BJ_Forget);
    1785           0 :                 may_free = 0;
    1786             :         } else {
    1787             :                 JBUFFER_TRACE(jh, "on running transaction");
    1788           0 :                 journal_remove_journal_head(bh);
    1789           0 :                 __brelse(bh);
    1790             :         }
    1791           0 :         return may_free;
    1792             : }
    1793             : 
    1794             : /*
    1795             :  * journal_invalidatepage
    1796             :  *
    1797             :  * This code is tricky.  It has a number of cases to deal with.
    1798             :  *
    1799             :  * There are two invariants which this code relies on:
    1800             :  *
    1801             :  * i_size must be updated on disk before we start calling invalidatepage on the
    1802             :  * data.
    1803             :  *
    1804             :  *  This is done in ext3 by defining an ext3_setattr method which
    1805             :  *  updates i_size before truncate gets going.  By maintaining this
    1806             :  *  invariant, we can be sure that it is safe to throw away any buffers
    1807             :  *  attached to the current transaction: once the transaction commits,
    1808             :  *  we know that the data will not be needed.
    1809             :  *
    1810             :  *  Note however that we can *not* throw away data belonging to the
    1811             :  *  previous, committing transaction!
    1812             :  *
    1813             :  * Any disk blocks which *are* part of the previous, committing
    1814             :  * transaction (and which therefore cannot be discarded immediately) are
    1815             :  * not going to be reused in the new running transaction
    1816             :  *
    1817             :  *  The bitmap committed_data images guarantee this: any block which is
    1818             :  *  allocated in one transaction and removed in the next will be marked
    1819             :  *  as in-use in the committed_data bitmap, so cannot be reused until
    1820             :  *  the next transaction to delete the block commits.  This means that
    1821             :  *  leaving committing buffers dirty is quite safe: the disk blocks
    1822             :  *  cannot be reallocated to a different file and so buffer aliasing is
    1823             :  *  not possible.
    1824             :  *
    1825             :  *
    1826             :  * The above applies mainly to ordered data mode.  In writeback mode we
    1827             :  * don't make guarantees about the order in which data hits disk --- in
    1828             :  * particular we don't guarantee that new dirty data is flushed before
    1829             :  * transaction commit --- so it is always safe just to discard data
    1830             :  * immediately in that mode.  --sct
    1831             :  */
    1832             : 
    1833             : /*
    1834             :  * The journal_unmap_buffer helper function returns zero if the buffer
    1835             :  * concerned remains pinned as an anonymous buffer belonging to an older
    1836             :  * transaction.
    1837             :  *
    1838             :  * We're outside-transaction here.  Either or both of j_running_transaction
    1839             :  * and j_committing_transaction may be NULL.
    1840             :  */
    1841             : static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh)
    1842             : {
    1843           0 :         transaction_t *transaction;
    1844           0 :         struct journal_head *jh;
    1845           0 :         int may_free = 1;
    1846           0 :         int ret;
    1847           0 : 
    1848           0 :         BUFFER_TRACE(bh, "entry");
    1849           0 : 
    1850           0 :         /*
    1851           0 :          * It is safe to proceed here without the j_list_lock because the
    1852           0 :          * buffers cannot be stolen by try_to_free_buffers as long as we are
    1853             :          * holding the page lock. --sct
    1854             :          */
    1855             : 
    1856           0 :         if (!buffer_jbd(bh))
    1857           0 :                 goto zap_buffer_unlocked;
    1858             : 
    1859           0 :         spin_lock(&journal->j_state_lock);
    1860           0 :         jbd_lock_bh_state(bh);
    1861           0 :         spin_lock(&journal->j_list_lock);
    1862             : 
    1863           0 :         jh = journal_grab_journal_head(bh);
    1864           0 :         if (!jh)
    1865           0 :                 goto zap_buffer_no_jh;
    1866             : 
    1867           0 :         transaction = jh->b_transaction;
    1868           0 :         if (transaction == NULL) {
    1869             :                 /* First case: not on any transaction.  If it
    1870             :                  * has no checkpoint link, then we can zap it:
    1871             :                  * it's a writeback-mode buffer so we don't care
    1872             :                  * if it hits disk safely. */
    1873           0 :                 if (!jh->b_cp_transaction) {
    1874             :                         JBUFFER_TRACE(jh, "not on any transaction: zap");
    1875           0 :                         goto zap_buffer;
    1876             :                 }
    1877             : 
    1878           0 :                 if (!buffer_dirty(bh)) {
    1879             :                         /* bdflush has written it.  We can drop it now */
    1880           0 :                         goto zap_buffer;
    1881             :                 }
    1882             : 
    1883             :                 /* OK, it must be in the journal but still not
    1884             :                  * written fully to disk: it's metadata or
    1885             :                  * journaled data... */
    1886             : 
    1887           0 :                 if (journal->j_running_transaction) {
    1888             :                         /* ... and once the current transaction has
    1889             :                          * committed, the buffer won't be needed any
    1890             :                          * longer. */
    1891             :                         JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
    1892           0 :                         ret = __dispose_buffer(jh,
    1893             :                                         journal->j_running_transaction);
    1894           0 :                         journal_put_journal_head(jh);
    1895           0 :                         spin_unlock(&journal->j_list_lock);
    1896           0 :                         jbd_unlock_bh_state(bh);
    1897           0 :                         spin_unlock(&journal->j_state_lock);
    1898           0 :                         return ret;
    1899             :                 } else {
    1900             :                         /* There is no currently-running transaction. So the
    1901             :                          * orphan record which we wrote for this file must have
    1902             :                          * passed into commit.  We must attach this buffer to
    1903             :                          * the committing transaction, if it exists. */
    1904           0 :                         if (journal->j_committing_transaction) {
    1905             :                                 JBUFFER_TRACE(jh, "give to committing trans");
    1906           0 :                                 ret = __dispose_buffer(jh,
    1907             :                                         journal->j_committing_transaction);
    1908           0 :                                 journal_put_journal_head(jh);
    1909           0 :                                 spin_unlock(&journal->j_list_lock);
    1910           0 :                                 jbd_unlock_bh_state(bh);
    1911           0 :                                 spin_unlock(&journal->j_state_lock);
    1912           0 :                                 return ret;
    1913             :                         } else {
    1914             :                                 /* The orphan record's transaction has
    1915             :                                  * committed.  We can cleanse this buffer */
    1916           0 :                                 clear_buffer_jbddirty(bh);
    1917           0 :                                 goto zap_buffer;
    1918             :                         }
    1919             :                 }
    1920           0 :         } else if (transaction == journal->j_committing_transaction) {
    1921             :                 JBUFFER_TRACE(jh, "on committing transaction");
    1922           0 :                 if (jh->b_jlist == BJ_Locked) {
    1923             :                         /*
    1924             :                          * The buffer is on the committing transaction's locked
    1925             :                          * list.  We have the buffer locked, so I/O has
    1926             :                          * completed.  So we can nail the buffer now.
    1927             :                          */
    1928           0 :                         may_free = __dispose_buffer(jh, transaction);
    1929           0 :                         goto zap_buffer;
    1930             :                 }
    1931             :                 /*
    1932             :                  * If it is committing, we simply cannot touch it.  We
    1933             :                  * can remove it's next_transaction pointer from the
    1934             :                  * running transaction if that is set, but nothing
    1935             :                  * else. */
    1936           0 :                 set_buffer_freed(bh);
    1937           0 :                 if (jh->b_next_transaction) {
    1938           0 :                         J_ASSERT(jh->b_next_transaction ==
    1939             :                                         journal->j_running_transaction);
    1940           0 :                         jh->b_next_transaction = NULL;
    1941             :                 }
    1942           0 :                 journal_put_journal_head(jh);
    1943           0 :                 spin_unlock(&journal->j_list_lock);
    1944           0 :                 jbd_unlock_bh_state(bh);
    1945           0 :                 spin_unlock(&journal->j_state_lock);
    1946           0 :                 return 0;
    1947             :         } else {
    1948             :                 /* Good, the buffer belongs to the running transaction.
    1949             :                  * We are writing our own transaction's data, not any
    1950             :                  * previous one's, so it is safe to throw it away
    1951             :                  * (remember that we expect the filesystem to have set
    1952             :                  * i_size already for this truncate so recovery will not
    1953             :                  * expose the disk blocks we are discarding here.) */
    1954           0 :                 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
    1955             :                 JBUFFER_TRACE(jh, "on running transaction");
    1956           0 :                 may_free = __dispose_buffer(jh, transaction);
    1957             :         }
    1958             : 
    1959           0 : zap_buffer:
    1960           0 :         journal_put_journal_head(jh);
    1961             : zap_buffer_no_jh:
    1962           0 :         spin_unlock(&journal->j_list_lock);
    1963           0 :         jbd_unlock_bh_state(bh);
    1964           0 :         spin_unlock(&journal->j_state_lock);
    1965             : zap_buffer_unlocked:
    1966           0 :         clear_buffer_dirty(bh);
    1967           0 :         J_ASSERT_BH(bh, !buffer_jbddirty(bh));
    1968           0 :         clear_buffer_mapped(bh);
    1969           0 :         clear_buffer_req(bh);
    1970           0 :         clear_buffer_new(bh);
    1971           0 :         bh->b_bdev = NULL;
    1972           0 :         return may_free;
    1973             : }
    1974             : 
    1975             : /**
    1976             :  * void journal_invalidatepage() - invalidate a journal page
    1977             :  * @journal: journal to use for flush
    1978             :  * @page:    page to flush
    1979             :  * @offset:  length of page to invalidate.
    1980             :  *
    1981             :  * Reap page buffers containing data after offset in page.
    1982             :  */
    1983             : void journal_invalidatepage(journal_t *journal,
    1984             :                       struct page *page,
    1985           0 :                       unsigned long offset)
    1986           0 : {
    1987           0 :         struct buffer_head *head, *bh, *next;
    1988           0 :         unsigned int curr_off = 0;
    1989           0 :         int may_free = 1;
    1990           0 : 
    1991           0 :         if (!PageLocked(page))
    1992           0 :                 BUG();
    1993           0 :         if (!page_has_buffers(page))
    1994           0 :                 return;
    1995           0 : 
    1996           0 :         /* We will potentially be playing with lists other than just the
    1997           0 :          * data lists (especially for journaled data mode), so be
    1998           0 :          * cautious in our locking. */
    1999             : 
    2000           0 :         head = bh = page_buffers(page);
    2001           0 :         do {
    2002           0 :                 unsigned int next_off = curr_off + bh->b_size;
    2003           0 :                 next = bh->b_this_page;
    2004             : 
    2005           0 :                 if (offset <= curr_off) {
    2006             :                         /* This block is wholly outside the truncation point */
    2007           0 :                         lock_buffer(bh);
    2008           0 :                         may_free &= journal_unmap_buffer(journal, bh);
    2009           0 :                         unlock_buffer(bh);
    2010             :                 }
    2011           0 :                 curr_off = next_off;
    2012           0 :                 bh = next;
    2013             : 
    2014           0 :         } while (bh != head);
    2015             : 
    2016           0 :         if (!offset) {
    2017           0 :                 if (may_free && try_to_free_buffers(page))
    2018           0 :                         J_ASSERT(!page_has_buffers(page));
    2019             :         }
    2020           0 : }
    2021             : 
    2022             : /*
    2023             :  * File a buffer on the given transaction list.
    2024             :  */
    2025             : void __journal_file_buffer(struct journal_head *jh,
    2026             :                         transaction_t *transaction, int jlist)
    2027             : {
    2028           0 :         struct journal_head **list = NULL;
    2029           0 :         int was_dirty = 0;
    2030           0 :         struct buffer_head *bh = jh2bh(jh);
    2031           0 : 
    2032           0 :         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
    2033           0 :         assert_spin_locked(&transaction->t_journal->j_list_lock);
    2034           0 : 
    2035           0 :         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
    2036           0 :         J_ASSERT_JH(jh, jh->b_transaction == transaction ||
    2037           0 :                                 jh->b_transaction == NULL);
    2038           0 : 
    2039           0 :         if (jh->b_transaction && jh->b_jlist == jlist)
    2040           0 :                 return;
    2041           0 : 
    2042           0 :         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
    2043             :             jlist == BJ_Shadow || jlist == BJ_Forget) {
    2044             :                 /*
    2045             :                  * For metadata buffers, we track dirty bit in buffer_jbddirty
    2046             :                  * instead of buffer_dirty. We should not see a dirty bit set
    2047             :                  * here because we clear it in do_get_write_access but e.g.
    2048             :                  * tune2fs can modify the sb and set the dirty bit at any time
    2049             :                  * so we try to gracefully handle that.
    2050             :                  */
    2051           0 :                 if (buffer_dirty(bh))
    2052           0 :                         warn_dirty_buffer(bh);
    2053           0 :                 if (test_clear_buffer_dirty(bh) ||
    2054             :                     test_clear_buffer_jbddirty(bh))
    2055           0 :                         was_dirty = 1;
    2056             :         }
    2057             : 
    2058           0 :         if (jh->b_transaction)
    2059           0 :                 __journal_temp_unlink_buffer(jh);
    2060           0 :         jh->b_transaction = transaction;
    2061             : 
    2062           0 :         switch (jlist) {
    2063           0 :         case BJ_None:
    2064           0 :                 J_ASSERT_JH(jh, !jh->b_committed_data);
    2065           0 :                 J_ASSERT_JH(jh, !jh->b_frozen_data);
    2066           0 :                 return;
    2067           0 :         case BJ_SyncData:
    2068           0 :                 list = &transaction->t_sync_datalist;
    2069           0 :                 break;
    2070           0 :         case BJ_Metadata:
    2071           0 :                 transaction->t_nr_buffers++;
    2072           0 :                 list = &transaction->t_buffers;
    2073           0 :                 break;
    2074           0 :         case BJ_Forget:
    2075           0 :                 list = &transaction->t_forget;
    2076           0 :                 break;
    2077           0 :         case BJ_IO:
    2078           0 :                 list = &transaction->t_iobuf_list;
    2079           0 :                 break;
    2080           0 :         case BJ_Shadow:
    2081           0 :                 list = &transaction->t_shadow_list;
    2082           0 :                 break;
    2083           0 :         case BJ_LogCtl:
    2084           0 :                 list = &transaction->t_log_list;
    2085           0 :                 break;
    2086           0 :         case BJ_Reserved:
    2087           0 :                 list = &transaction->t_reserved_list;
    2088           0 :                 break;
    2089           0 :         case BJ_Locked:
    2090           0 :                 list =  &transaction->t_locked_list;
    2091           0 :                 break;
    2092           0 :         }
    2093             : 
    2094           0 :         __blist_add_buffer(list, jh);
    2095           0 :         jh->b_jlist = jlist;
    2096             : 
    2097           0 :         if (was_dirty)
    2098           0 :                 set_buffer_jbddirty(bh);
    2099           0 : }
    2100             : 
    2101             : void journal_file_buffer(struct journal_head *jh,
    2102             :                                 transaction_t *transaction, int jlist)
    2103           0 : {
    2104           0 :         jbd_lock_bh_state(jh2bh(jh));
    2105           0 :         spin_lock(&transaction->t_journal->j_list_lock);
    2106           0 :         __journal_file_buffer(jh, transaction, jlist);
    2107           0 :         spin_unlock(&transaction->t_journal->j_list_lock);
    2108           0 :         jbd_unlock_bh_state(jh2bh(jh));
    2109           0 : }
    2110             : 
    2111             : /*
    2112             :  * Remove a buffer from its current buffer list in preparation for
    2113             :  * dropping it from its current transaction entirely.  If the buffer has
    2114             :  * already started to be used by a subsequent transaction, refile the
    2115             :  * buffer on that transaction's metadata list.
    2116             :  *
    2117             :  * Called under journal->j_list_lock
    2118             :  *
    2119             :  * Called under jbd_lock_bh_state(jh2bh(jh))
    2120             :  */
    2121             : void __journal_refile_buffer(struct journal_head *jh)
    2122             : {
    2123           0 :         int was_dirty;
    2124           0 :         struct buffer_head *bh = jh2bh(jh);
    2125           0 : 
    2126           0 :         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
    2127           0 :         if (jh->b_transaction)
    2128           0 :                 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
    2129             : 
    2130             :         /* If the buffer is now unused, just drop it. */
    2131           0 :         if (jh->b_next_transaction == NULL) {
    2132           0 :                 __journal_unfile_buffer(jh);
    2133           0 :                 return;
    2134             :         }
    2135             : 
    2136             :         /*
    2137             :          * It has been modified by a later transaction: add it to the new
    2138             :          * transaction's metadata list.
    2139             :          */
    2140             : 
    2141           0 :         was_dirty = test_clear_buffer_jbddirty(bh);
    2142           0 :         __journal_temp_unlink_buffer(jh);
    2143           0 :         jh->b_transaction = jh->b_next_transaction;
    2144           0 :         jh->b_next_transaction = NULL;
    2145           0 :         __journal_file_buffer(jh, jh->b_transaction,
    2146             :                                 jh->b_modified ? BJ_Metadata : BJ_Reserved);
    2147           0 :         J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
    2148             : 
    2149           0 :         if (was_dirty)
    2150           0 :                 set_buffer_jbddirty(bh);
    2151           0 : }
    2152             : 
    2153             : /*
    2154             :  * For the unlocked version of this call, also make sure that any
    2155             :  * hanging journal_head is cleaned up if necessary.
    2156             :  *
    2157             :  * __journal_refile_buffer is usually called as part of a single locked
    2158             :  * operation on a buffer_head, in which the caller is probably going to
    2159             :  * be hooking the journal_head onto other lists.  In that case it is up
    2160             :  * to the caller to remove the journal_head if necessary.  For the
    2161             :  * unlocked journal_refile_buffer call, the caller isn't going to be
    2162             :  * doing anything else to the buffer so we need to do the cleanup
    2163             :  * ourselves to avoid a jh leak.
    2164             :  *
    2165             :  * *** The journal_head may be freed by this call! ***
    2166             :  */
    2167             : void journal_refile_buffer(journal_t *journal, struct journal_head *jh)
    2168             : {
    2169           0 :         struct buffer_head *bh = jh2bh(jh);
    2170           0 : 
    2171           0 :         jbd_lock_bh_state(bh);
    2172           0 :         spin_lock(&journal->j_list_lock);
    2173             : 
    2174           0 :         __journal_refile_buffer(jh);
    2175           0 :         jbd_unlock_bh_state(bh);
    2176           0 :         journal_remove_journal_head(bh);
    2177             : 
    2178           0 :         spin_unlock(&journal->j_list_lock);
    2179           0 :         __brelse(bh);
    2180           0 : }

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