LCOV - code coverage report
Current view: top level - fs/jbd2 - transaction.c (source / functions) Hit Total Coverage
Test: Real Lines: 417 681 61.2 %
Date: 2020-10-17 15:46:16 Functions: 0 46 0.0 %
Legend: Neither, QEMU, Real, Both Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : // SPDX-License-Identifier: GPL-2.0+
       2                 :            : /*
       3                 :            :  * linux/fs/jbd2/transaction.c
       4                 :            :  *
       5                 :            :  * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
       6                 :            :  *
       7                 :            :  * Copyright 1998 Red Hat corp --- All Rights Reserved
       8                 :            :  *
       9                 :            :  * Generic filesystem transaction handling code; part of the ext2fs
      10                 :            :  * journaling system.
      11                 :            :  *
      12                 :            :  * This file manages transactions (compound commits managed by the
      13                 :            :  * journaling code) and handles (individual atomic operations by the
      14                 :            :  * filesystem).
      15                 :            :  */
      16                 :            : 
      17                 :            : #include <linux/time.h>
      18                 :            : #include <linux/fs.h>
      19                 :            : #include <linux/jbd2.h>
      20                 :            : #include <linux/errno.h>
      21                 :            : #include <linux/slab.h>
      22                 :            : #include <linux/timer.h>
      23                 :            : #include <linux/mm.h>
      24                 :            : #include <linux/highmem.h>
      25                 :            : #include <linux/hrtimer.h>
      26                 :            : #include <linux/backing-dev.h>
      27                 :            : #include <linux/bug.h>
      28                 :            : #include <linux/module.h>
      29                 :            : #include <linux/sched/mm.h>
      30                 :            : 
      31                 :            : #include <trace/events/jbd2.h>
      32                 :            : 
      33                 :            : static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh);
      34                 :            : static void __jbd2_journal_unfile_buffer(struct journal_head *jh);
      35                 :            : 
      36                 :            : static struct kmem_cache *transaction_cache;
      37                 :          3 : int __init jbd2_journal_init_transaction_cache(void)
      38                 :            : {
      39                 :          3 :         J_ASSERT(!transaction_cache);
      40                 :          3 :         transaction_cache = kmem_cache_create("jbd2_transaction_s",
      41                 :            :                                         sizeof(transaction_t),
      42                 :            :                                         0,
      43                 :            :                                         SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY,
      44                 :            :                                         NULL);
      45                 :          3 :         if (!transaction_cache) {
      46                 :          0 :                 pr_emerg("JBD2: failed to create transaction cache\n");
      47                 :          0 :                 return -ENOMEM;
      48                 :            :         }
      49                 :            :         return 0;
      50                 :            : }
      51                 :            : 
      52                 :          0 : void jbd2_journal_destroy_transaction_cache(void)
      53                 :            : {
      54                 :          0 :         kmem_cache_destroy(transaction_cache);
      55                 :          0 :         transaction_cache = NULL;
      56                 :          0 : }
      57                 :            : 
      58                 :          3 : void jbd2_journal_free_transaction(transaction_t *transaction)
      59                 :            : {
      60                 :          3 :         if (unlikely(ZERO_OR_NULL_PTR(transaction)))
      61                 :          3 :                 return;
      62                 :          3 :         kmem_cache_free(transaction_cache, transaction);
      63                 :            : }
      64                 :            : 
      65                 :            : /*
      66                 :            :  * jbd2_get_transaction: obtain a new transaction_t object.
      67                 :            :  *
      68                 :            :  * Simply initialise a new transaction. Initialize it in
      69                 :            :  * RUNNING state and add it to the current journal (which should not
      70                 :            :  * have an existing running transaction: we only make a new transaction
      71                 :            :  * once we have started to commit the old one).
      72                 :            :  *
      73                 :            :  * Preconditions:
      74                 :            :  *      The journal MUST be locked.  We don't perform atomic mallocs on the
      75                 :            :  *      new transaction and we can't block without protecting against other
      76                 :            :  *      processes trying to touch the journal while it is in transition.
      77                 :            :  *
      78                 :            :  */
      79                 :            : 
      80                 :          3 : static void jbd2_get_transaction(journal_t *journal,
      81                 :            :                                 transaction_t *transaction)
      82                 :            : {
      83                 :          3 :         transaction->t_journal = journal;
      84                 :          3 :         transaction->t_state = T_RUNNING;
      85                 :          3 :         transaction->t_start_time = ktime_get();
      86                 :          3 :         transaction->t_tid = journal->j_transaction_sequence++;
      87                 :          3 :         transaction->t_expires = jiffies + journal->j_commit_interval;
      88                 :          3 :         spin_lock_init(&transaction->t_handle_lock);
      89                 :            :         atomic_set(&transaction->t_updates, 0);
      90                 :            :         atomic_set(&transaction->t_outstanding_credits,
      91                 :            :                    atomic_read(&journal->j_reserved_credits));
      92                 :            :         atomic_set(&transaction->t_handle_count, 0);
      93                 :          3 :         INIT_LIST_HEAD(&transaction->t_inode_list);
      94                 :          3 :         INIT_LIST_HEAD(&transaction->t_private_list);
      95                 :            : 
      96                 :            :         /* Set up the commit timer for the new transaction. */
      97                 :          3 :         journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires);
      98                 :          3 :         add_timer(&journal->j_commit_timer);
      99                 :            : 
     100                 :          3 :         J_ASSERT(journal->j_running_transaction == NULL);
     101                 :          3 :         journal->j_running_transaction = transaction;
     102                 :          3 :         transaction->t_max_wait = 0;
     103                 :          3 :         transaction->t_start = jiffies;
     104                 :          3 :         transaction->t_requested = 0;
     105                 :          3 : }
     106                 :            : 
     107                 :            : /*
     108                 :            :  * Handle management.
     109                 :            :  *
     110                 :            :  * A handle_t is an object which represents a single atomic update to a
     111                 :            :  * filesystem, and which tracks all of the modifications which form part
     112                 :            :  * of that one update.
     113                 :            :  */
     114                 :            : 
     115                 :            : /*
     116                 :            :  * Update transaction's maximum wait time, if debugging is enabled.
     117                 :            :  *
     118                 :            :  * In order for t_max_wait to be reliable, it must be protected by a
     119                 :            :  * lock.  But doing so will mean that start_this_handle() can not be
     120                 :            :  * run in parallel on SMP systems, which limits our scalability.  So
     121                 :            :  * unless debugging is enabled, we no longer update t_max_wait, which
     122                 :            :  * means that maximum wait time reported by the jbd2_run_stats
     123                 :            :  * tracepoint will always be zero.
     124                 :            :  */
     125                 :            : static inline void update_t_max_wait(transaction_t *transaction,
     126                 :            :                                      unsigned long ts)
     127                 :            : {
     128                 :            : #ifdef CONFIG_JBD2_DEBUG
     129                 :            :         if (jbd2_journal_enable_debug &&
     130                 :            :             time_after(transaction->t_start, ts)) {
     131                 :            :                 ts = jbd2_time_diff(ts, transaction->t_start);
     132                 :            :                 spin_lock(&transaction->t_handle_lock);
     133                 :            :                 if (ts > transaction->t_max_wait)
     134                 :            :                         transaction->t_max_wait = ts;
     135                 :            :                 spin_unlock(&transaction->t_handle_lock);
     136                 :            :         }
     137                 :            : #endif
     138                 :            : }
     139                 :            : 
     140                 :            : /*
     141                 :            :  * Wait until running transaction passes to T_FLUSH state and new transaction
     142                 :            :  * can thus be started. Also starts the commit if needed. The function expects
     143                 :            :  * running transaction to exist and releases j_state_lock.
     144                 :            :  */
     145                 :          3 : static void wait_transaction_locked(journal_t *journal)
     146                 :            :         __releases(journal->j_state_lock)
     147                 :            : {
     148                 :          3 :         DEFINE_WAIT(wait);
     149                 :            :         int need_to_start;
     150                 :          3 :         tid_t tid = journal->j_running_transaction->t_tid;
     151                 :            : 
     152                 :          3 :         prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
     153                 :            :                         TASK_UNINTERRUPTIBLE);
     154                 :          3 :         need_to_start = !tid_geq(journal->j_commit_request, tid);
     155                 :            :         read_unlock(&journal->j_state_lock);
     156                 :          3 :         if (need_to_start)
     157                 :          0 :                 jbd2_log_start_commit(journal, tid);
     158                 :            :         jbd2_might_wait_for_commit(journal);
     159                 :          3 :         schedule();
     160                 :          3 :         finish_wait(&journal->j_wait_transaction_locked, &wait);
     161                 :          3 : }
     162                 :            : 
     163                 :            : /*
     164                 :            :  * Wait until running transaction transitions from T_SWITCH to T_FLUSH
     165                 :            :  * state and new transaction can thus be started. The function releases
     166                 :            :  * j_state_lock.
     167                 :            :  */
     168                 :          0 : static void wait_transaction_switching(journal_t *journal)
     169                 :            :         __releases(journal->j_state_lock)
     170                 :            : {
     171                 :          0 :         DEFINE_WAIT(wait);
     172                 :            : 
     173                 :          0 :         if (WARN_ON(!journal->j_running_transaction ||
     174                 :            :                     journal->j_running_transaction->t_state != T_SWITCH))
     175                 :          0 :                 return;
     176                 :          0 :         prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
     177                 :            :                         TASK_UNINTERRUPTIBLE);
     178                 :            :         read_unlock(&journal->j_state_lock);
     179                 :            :         /*
     180                 :            :          * We don't call jbd2_might_wait_for_commit() here as there's no
     181                 :            :          * waiting for outstanding handles happening anymore in T_SWITCH state
     182                 :            :          * and handling of reserved handles actually relies on that for
     183                 :            :          * correctness.
     184                 :            :          */
     185                 :          0 :         schedule();
     186                 :          0 :         finish_wait(&journal->j_wait_transaction_locked, &wait);
     187                 :            : }
     188                 :            : 
     189                 :          0 : static void sub_reserved_credits(journal_t *journal, int blocks)
     190                 :            : {
     191                 :          0 :         atomic_sub(blocks, &journal->j_reserved_credits);
     192                 :          0 :         wake_up(&journal->j_wait_reserved);
     193                 :          0 : }
     194                 :            : 
     195                 :            : /*
     196                 :            :  * Wait until we can add credits for handle to the running transaction.  Called
     197                 :            :  * with j_state_lock held for reading. Returns 0 if handle joined the running
     198                 :            :  * transaction. Returns 1 if we had to wait, j_state_lock is dropped, and
     199                 :            :  * caller must retry.
     200                 :            :  */
     201                 :          3 : static int add_transaction_credits(journal_t *journal, int blocks,
     202                 :            :                                    int rsv_blocks)
     203                 :            : {
     204                 :          3 :         transaction_t *t = journal->j_running_transaction;
     205                 :            :         int needed;
     206                 :          3 :         int total = blocks + rsv_blocks;
     207                 :            : 
     208                 :            :         /*
     209                 :            :          * If the current transaction is locked down for commit, wait
     210                 :            :          * for the lock to be released.
     211                 :            :          */
     212                 :          3 :         if (t->t_state != T_RUNNING) {
     213                 :          3 :                 WARN_ON_ONCE(t->t_state >= T_FLUSH);
     214                 :          3 :                 wait_transaction_locked(journal);
     215                 :          3 :                 return 1;
     216                 :            :         }
     217                 :            : 
     218                 :            :         /*
     219                 :            :          * If there is not enough space left in the log to write all
     220                 :            :          * potential buffers requested by this operation, we need to
     221                 :            :          * stall pending a log checkpoint to free some more log space.
     222                 :            :          */
     223                 :          3 :         needed = atomic_add_return(total, &t->t_outstanding_credits);
     224                 :          3 :         if (needed > journal->j_max_transaction_buffers) {
     225                 :            :                 /*
     226                 :            :                  * If the current transaction is already too large,
     227                 :            :                  * then start to commit it: we can then go back and
     228                 :            :                  * attach this handle to a new transaction.
     229                 :            :                  */
     230                 :            :                 atomic_sub(total, &t->t_outstanding_credits);
     231                 :            : 
     232                 :            :                 /*
     233                 :            :                  * Is the number of reserved credits in the current transaction too
     234                 :            :                  * big to fit this handle? Wait until reserved credits are freed.
     235                 :            :                  */
     236                 :          0 :                 if (atomic_read(&journal->j_reserved_credits) + total >
     237                 :          0 :                     journal->j_max_transaction_buffers) {
     238                 :            :                         read_unlock(&journal->j_state_lock);
     239                 :            :                         jbd2_might_wait_for_commit(journal);
     240                 :          0 :                         wait_event(journal->j_wait_reserved,
     241                 :            :                                    atomic_read(&journal->j_reserved_credits) + total <=
     242                 :            :                                    journal->j_max_transaction_buffers);
     243                 :            :                         return 1;
     244                 :            :                 }
     245                 :            : 
     246                 :          0 :                 wait_transaction_locked(journal);
     247                 :          0 :                 return 1;
     248                 :            :         }
     249                 :            : 
     250                 :            :         /*
     251                 :            :          * The commit code assumes that it can get enough log space
     252                 :            :          * without forcing a checkpoint.  This is *critical* for
     253                 :            :          * correctness: a checkpoint of a buffer which is also
     254                 :            :          * associated with a committing transaction creates a deadlock,
     255                 :            :          * so commit simply cannot force through checkpoints.
     256                 :            :          *
     257                 :            :          * We must therefore ensure the necessary space in the journal
     258                 :            :          * *before* starting to dirty potentially checkpointed buffers
     259                 :            :          * in the new transaction.
     260                 :            :          */
     261                 :          3 :         if (jbd2_log_space_left(journal) < jbd2_space_needed(journal)) {
     262                 :            :                 atomic_sub(total, &t->t_outstanding_credits);
     263                 :            :                 read_unlock(&journal->j_state_lock);
     264                 :            :                 jbd2_might_wait_for_commit(journal);
     265                 :          0 :                 write_lock(&journal->j_state_lock);
     266                 :          0 :                 if (jbd2_log_space_left(journal) < jbd2_space_needed(journal))
     267                 :          0 :                         __jbd2_log_wait_for_space(journal);
     268                 :            :                 write_unlock(&journal->j_state_lock);
     269                 :          0 :                 return 1;
     270                 :            :         }
     271                 :            : 
     272                 :            :         /* No reservation? We are done... */
     273                 :          3 :         if (!rsv_blocks)
     274                 :            :                 return 0;
     275                 :            : 
     276                 :          0 :         needed = atomic_add_return(rsv_blocks, &journal->j_reserved_credits);
     277                 :            :         /* We allow at most half of a transaction to be reserved */
     278                 :          0 :         if (needed > journal->j_max_transaction_buffers / 2) {
     279                 :          0 :                 sub_reserved_credits(journal, rsv_blocks);
     280                 :            :                 atomic_sub(total, &t->t_outstanding_credits);
     281                 :            :                 read_unlock(&journal->j_state_lock);
     282                 :            :                 jbd2_might_wait_for_commit(journal);
     283                 :          0 :                 wait_event(journal->j_wait_reserved,
     284                 :            :                          atomic_read(&journal->j_reserved_credits) + rsv_blocks
     285                 :            :                          <= journal->j_max_transaction_buffers / 2);
     286                 :            :                 return 1;
     287                 :            :         }
     288                 :            :         return 0;
     289                 :            : }
     290                 :            : 
     291                 :            : /*
     292                 :            :  * start_this_handle: Given a handle, deal with any locking or stalling
     293                 :            :  * needed to make sure that there is enough journal space for the handle
     294                 :            :  * to begin.  Attach the handle to a transaction and set up the
     295                 :            :  * transaction's buffer credits.
     296                 :            :  */
     297                 :            : 
     298                 :          3 : static int start_this_handle(journal_t *journal, handle_t *handle,
     299                 :            :                              gfp_t gfp_mask)
     300                 :            : {
     301                 :            :         transaction_t   *transaction, *new_transaction = NULL;
     302                 :          3 :         int             blocks = handle->h_buffer_credits;
     303                 :            :         int             rsv_blocks = 0;
     304                 :          3 :         unsigned long ts = jiffies;
     305                 :            : 
     306                 :          3 :         if (handle->h_rsv_handle)
     307                 :          0 :                 rsv_blocks = handle->h_rsv_handle->h_buffer_credits;
     308                 :            : 
     309                 :            :         /*
     310                 :            :          * Limit the number of reserved credits to 1/2 of maximum transaction
     311                 :            :          * size and limit the number of total credits to not exceed maximum
     312                 :            :          * transaction size per operation.
     313                 :            :          */
     314                 :          3 :         if ((rsv_blocks > journal->j_max_transaction_buffers / 2) ||
     315                 :          3 :             (rsv_blocks + blocks > journal->j_max_transaction_buffers)) {
     316                 :          1 :                 printk(KERN_ERR "JBD2: %s wants too many credits "
     317                 :            :                        "credits:%d rsv_credits:%d max:%d\n",
     318                 :          1 :                        current->comm, blocks, rsv_blocks,
     319                 :            :                        journal->j_max_transaction_buffers);
     320                 :          0 :                 WARN_ON(1);
     321                 :          0 :                 return -ENOSPC;
     322                 :            :         }
     323                 :            : 
     324                 :            : alloc_transaction:
     325                 :          3 :         if (!journal->j_running_transaction) {
     326                 :            :                 /*
     327                 :            :                  * If __GFP_FS is not present, then we may be being called from
     328                 :            :                  * inside the fs writeback layer, so we MUST NOT fail.
     329                 :            :                  */
     330                 :          3 :                 if ((gfp_mask & __GFP_FS) == 0)
     331                 :          3 :                         gfp_mask |= __GFP_NOFAIL;
     332                 :          3 :                 new_transaction = kmem_cache_zalloc(transaction_cache,
     333                 :            :                                                     gfp_mask);
     334                 :          3 :                 if (!new_transaction)
     335                 :            :                         return -ENOMEM;
     336                 :            :         }
     337                 :            : 
     338                 :            :         jbd_debug(3, "New handle %p going live.\n", handle);
     339                 :            : 
     340                 :            :         /*
     341                 :            :          * We need to hold j_state_lock until t_updates has been incremented,
     342                 :            :          * for proper journal barrier handling
     343                 :            :          */
     344                 :            : repeat:
     345                 :          3 :         read_lock(&journal->j_state_lock);
     346                 :          3 :         BUG_ON(journal->j_flags & JBD2_UNMOUNT);
     347                 :          3 :         if (is_journal_aborted(journal) ||
     348                 :          3 :             (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
     349                 :            :                 read_unlock(&journal->j_state_lock);
     350                 :            :                 jbd2_journal_free_transaction(new_transaction);
     351                 :            :                 return -EROFS;
     352                 :            :         }
     353                 :            : 
     354                 :            :         /*
     355                 :            :          * Wait on the journal's transaction barrier if necessary. Specifically
     356                 :            :          * we allow reserved handles to proceed because otherwise commit could
     357                 :            :          * deadlock on page writeback not being able to complete.
     358                 :            :          */
     359                 :          3 :         if (!handle->h_reserved && journal->j_barrier_count) {
     360                 :            :                 read_unlock(&journal->j_state_lock);
     361                 :          0 :                 wait_event(journal->j_wait_transaction_locked,
     362                 :            :                                 journal->j_barrier_count == 0);
     363                 :            :                 goto repeat;
     364                 :            :         }
     365                 :            : 
     366                 :          3 :         if (!journal->j_running_transaction) {
     367                 :            :                 read_unlock(&journal->j_state_lock);
     368                 :          3 :                 if (!new_transaction)
     369                 :            :                         goto alloc_transaction;
     370                 :          3 :                 write_lock(&journal->j_state_lock);
     371                 :          3 :                 if (!journal->j_running_transaction &&
     372                 :          3 :                     (handle->h_reserved || !journal->j_barrier_count)) {
     373                 :          3 :                         jbd2_get_transaction(journal, new_transaction);
     374                 :            :                         new_transaction = NULL;
     375                 :            :                 }
     376                 :            :                 write_unlock(&journal->j_state_lock);
     377                 :            :                 goto repeat;
     378                 :            :         }
     379                 :            : 
     380                 :            :         transaction = journal->j_running_transaction;
     381                 :            : 
     382                 :          3 :         if (!handle->h_reserved) {
     383                 :            :                 /* We may have dropped j_state_lock - restart in that case */
     384                 :          3 :                 if (add_transaction_credits(journal, blocks, rsv_blocks))
     385                 :            :                         goto repeat;
     386                 :            :         } else {
     387                 :            :                 /*
     388                 :            :                  * We have handle reserved so we are allowed to join T_LOCKED
     389                 :            :                  * transaction and we don't have to check for transaction size
     390                 :            :                  * and journal space. But we still have to wait while running
     391                 :            :                  * transaction is being switched to a committing one as it
     392                 :            :                  * won't wait for any handles anymore.
     393                 :            :                  */
     394                 :          0 :                 if (transaction->t_state == T_SWITCH) {
     395                 :          0 :                         wait_transaction_switching(journal);
     396                 :          0 :                         goto repeat;
     397                 :            :                 }
     398                 :          0 :                 sub_reserved_credits(journal, blocks);
     399                 :          0 :                 handle->h_reserved = 0;
     400                 :            :         }
     401                 :            : 
     402                 :            :         /* OK, account for the buffers that this operation expects to
     403                 :            :          * use and add the handle to the running transaction. 
     404                 :            :          */
     405                 :            :         update_t_max_wait(transaction, ts);
     406                 :          3 :         handle->h_transaction = transaction;
     407                 :          3 :         handle->h_requested_credits = blocks;
     408                 :          3 :         handle->h_start_jiffies = jiffies;
     409                 :          3 :         atomic_inc(&transaction->t_updates);
     410                 :          3 :         atomic_inc(&transaction->t_handle_count);
     411                 :            :         jbd_debug(4, "Handle %p given %d credits (total %d, free %lu)\n",
     412                 :            :                   handle, blocks,
     413                 :            :                   atomic_read(&transaction->t_outstanding_credits),
     414                 :            :                   jbd2_log_space_left(journal));
     415                 :            :         read_unlock(&journal->j_state_lock);
     416                 :          3 :         current->journal_info = handle;
     417                 :            : 
     418                 :            :         rwsem_acquire_read(&journal->j_trans_commit_map, 0, 0, _THIS_IP_);
     419                 :            :         jbd2_journal_free_transaction(new_transaction);
     420                 :            :         /*
     421                 :            :          * Ensure that no allocations done while the transaction is open are
     422                 :            :          * going to recurse back to the fs layer.
     423                 :            :          */
     424                 :          3 :         handle->saved_alloc_context = memalloc_nofs_save();
     425                 :          3 :         return 0;
     426                 :            : }
     427                 :            : 
     428                 :            : /* Allocate a new handle.  This should probably be in a slab... */
     429                 :          3 : static handle_t *new_handle(int nblocks)
     430                 :            : {
     431                 :            :         handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
     432                 :          3 :         if (!handle)
     433                 :            :                 return NULL;
     434                 :          3 :         handle->h_buffer_credits = nblocks;
     435                 :          3 :         handle->h_ref = 1;
     436                 :            : 
     437                 :          3 :         return handle;
     438                 :            : }
     439                 :            : 
     440                 :          3 : handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
     441                 :            :                               gfp_t gfp_mask, unsigned int type,
     442                 :            :                               unsigned int line_no)
     443                 :            : {
     444                 :            :         handle_t *handle = journal_current_handle();
     445                 :            :         int err;
     446                 :            : 
     447                 :          3 :         if (!journal)
     448                 :            :                 return ERR_PTR(-EROFS);
     449                 :            : 
     450                 :          3 :         if (handle) {
     451                 :          3 :                 J_ASSERT(handle->h_transaction->t_journal == journal);
     452                 :          3 :                 handle->h_ref++;
     453                 :          3 :                 return handle;
     454                 :            :         }
     455                 :            : 
     456                 :          3 :         handle = new_handle(nblocks);
     457                 :          3 :         if (!handle)
     458                 :            :                 return ERR_PTR(-ENOMEM);
     459                 :          3 :         if (rsv_blocks) {
     460                 :            :                 handle_t *rsv_handle;
     461                 :            : 
     462                 :          0 :                 rsv_handle = new_handle(rsv_blocks);
     463                 :          0 :                 if (!rsv_handle) {
     464                 :            :                         jbd2_free_handle(handle);
     465                 :          0 :                         return ERR_PTR(-ENOMEM);
     466                 :            :                 }
     467                 :          0 :                 rsv_handle->h_reserved = 1;
     468                 :          0 :                 rsv_handle->h_journal = journal;
     469                 :          0 :                 handle->h_rsv_handle = rsv_handle;
     470                 :            :         }
     471                 :            : 
     472                 :          3 :         err = start_this_handle(journal, handle, gfp_mask);
     473                 :          3 :         if (err < 0) {
     474                 :          0 :                 if (handle->h_rsv_handle)
     475                 :            :                         jbd2_free_handle(handle->h_rsv_handle);
     476                 :            :                 jbd2_free_handle(handle);
     477                 :          0 :                 return ERR_PTR(err);
     478                 :            :         }
     479                 :          3 :         handle->h_type = type;
     480                 :          3 :         handle->h_line_no = line_no;
     481                 :          3 :         trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
     482                 :          3 :                                 handle->h_transaction->t_tid, type,
     483                 :            :                                 line_no, nblocks);
     484                 :            : 
     485                 :          3 :         return handle;
     486                 :            : }
     487                 :            : EXPORT_SYMBOL(jbd2__journal_start);
     488                 :            : 
     489                 :            : 
     490                 :            : /**
     491                 :            :  * handle_t *jbd2_journal_start() - Obtain a new handle.
     492                 :            :  * @journal: Journal to start transaction on.
     493                 :            :  * @nblocks: number of block buffer we might modify
     494                 :            :  *
     495                 :            :  * We make sure that the transaction can guarantee at least nblocks of
     496                 :            :  * modified buffers in the log.  We block until the log can guarantee
     497                 :            :  * that much space. Additionally, if rsv_blocks > 0, we also create another
     498                 :            :  * handle with rsv_blocks reserved blocks in the journal. This handle is
     499                 :            :  * is stored in h_rsv_handle. It is not attached to any particular transaction
     500                 :            :  * and thus doesn't block transaction commit. If the caller uses this reserved
     501                 :            :  * handle, it has to set h_rsv_handle to NULL as otherwise jbd2_journal_stop()
     502                 :            :  * on the parent handle will dispose the reserved one. Reserved handle has to
     503                 :            :  * be converted to a normal handle using jbd2_journal_start_reserved() before
     504                 :            :  * it can be used.
     505                 :            :  *
     506                 :            :  * Return a pointer to a newly allocated handle, or an ERR_PTR() value
     507                 :            :  * on failure.
     508                 :            :  */
     509                 :          0 : handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
     510                 :            : {
     511                 :          0 :         return jbd2__journal_start(journal, nblocks, 0, GFP_NOFS, 0, 0);
     512                 :            : }
     513                 :            : EXPORT_SYMBOL(jbd2_journal_start);
     514                 :            : 
     515                 :          0 : void jbd2_journal_free_reserved(handle_t *handle)
     516                 :            : {
     517                 :          0 :         journal_t *journal = handle->h_journal;
     518                 :            : 
     519                 :          0 :         WARN_ON(!handle->h_reserved);
     520                 :          0 :         sub_reserved_credits(journal, handle->h_buffer_credits);
     521                 :            :         jbd2_free_handle(handle);
     522                 :          0 : }
     523                 :            : EXPORT_SYMBOL(jbd2_journal_free_reserved);
     524                 :            : 
     525                 :            : /**
     526                 :            :  * int jbd2_journal_start_reserved() - start reserved handle
     527                 :            :  * @handle: handle to start
     528                 :            :  * @type: for handle statistics
     529                 :            :  * @line_no: for handle statistics
     530                 :            :  *
     531                 :            :  * Start handle that has been previously reserved with jbd2_journal_reserve().
     532                 :            :  * This attaches @handle to the running transaction (or creates one if there's
     533                 :            :  * not transaction running). Unlike jbd2_journal_start() this function cannot
     534                 :            :  * block on journal commit, checkpointing, or similar stuff. It can block on
     535                 :            :  * memory allocation or frozen journal though.
     536                 :            :  *
     537                 :            :  * Return 0 on success, non-zero on error - handle is freed in that case.
     538                 :            :  */
     539                 :          0 : int jbd2_journal_start_reserved(handle_t *handle, unsigned int type,
     540                 :            :                                 unsigned int line_no)
     541                 :            : {
     542                 :          0 :         journal_t *journal = handle->h_journal;
     543                 :            :         int ret = -EIO;
     544                 :            : 
     545                 :          0 :         if (WARN_ON(!handle->h_reserved)) {
     546                 :            :                 /* Someone passed in normal handle? Just stop it. */
     547                 :          0 :                 jbd2_journal_stop(handle);
     548                 :          0 :                 return ret;
     549                 :            :         }
     550                 :            :         /*
     551                 :            :          * Usefulness of mixing of reserved and unreserved handles is
     552                 :            :          * questionable. So far nobody seems to need it so just error out.
     553                 :            :          */
     554                 :          0 :         if (WARN_ON(current->journal_info)) {
     555                 :          0 :                 jbd2_journal_free_reserved(handle);
     556                 :          0 :                 return ret;
     557                 :            :         }
     558                 :            : 
     559                 :          0 :         handle->h_journal = NULL;
     560                 :            :         /*
     561                 :            :          * GFP_NOFS is here because callers are likely from writeback or
     562                 :            :          * similarly constrained call sites
     563                 :            :          */
     564                 :          0 :         ret = start_this_handle(journal, handle, GFP_NOFS);
     565                 :          0 :         if (ret < 0) {
     566                 :          0 :                 handle->h_journal = journal;
     567                 :          0 :                 jbd2_journal_free_reserved(handle);
     568                 :          0 :                 return ret;
     569                 :            :         }
     570                 :          0 :         handle->h_type = type;
     571                 :          0 :         handle->h_line_no = line_no;
     572                 :          0 :         trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
     573                 :          0 :                                 handle->h_transaction->t_tid, type,
     574                 :            :                                 line_no, handle->h_buffer_credits);
     575                 :          0 :         return 0;
     576                 :            : }
     577                 :            : EXPORT_SYMBOL(jbd2_journal_start_reserved);
     578                 :            : 
     579                 :            : /**
     580                 :            :  * int jbd2_journal_extend() - extend buffer credits.
     581                 :            :  * @handle:  handle to 'extend'
     582                 :            :  * @nblocks: nr blocks to try to extend by.
     583                 :            :  *
     584                 :            :  * Some transactions, such as large extends and truncates, can be done
     585                 :            :  * atomically all at once or in several stages.  The operation requests
     586                 :            :  * a credit for a number of buffer modifications in advance, but can
     587                 :            :  * extend its credit if it needs more.
     588                 :            :  *
     589                 :            :  * jbd2_journal_extend tries to give the running handle more buffer credits.
     590                 :            :  * It does not guarantee that allocation - this is a best-effort only.
     591                 :            :  * The calling process MUST be able to deal cleanly with a failure to
     592                 :            :  * extend here.
     593                 :            :  *
     594                 :            :  * Return 0 on success, non-zero on failure.
     595                 :            :  *
     596                 :            :  * return code < 0 implies an error
     597                 :            :  * return code > 0 implies normal transaction-full status.
     598                 :            :  */
     599                 :          1 : int jbd2_journal_extend(handle_t *handle, int nblocks)
     600                 :            : {
     601                 :          1 :         transaction_t *transaction = handle->h_transaction;
     602                 :            :         journal_t *journal;
     603                 :            :         int result;
     604                 :            :         int wanted;
     605                 :            : 
     606                 :          1 :         if (is_handle_aborted(handle))
     607                 :            :                 return -EROFS;
     608                 :          1 :         journal = transaction->t_journal;
     609                 :            : 
     610                 :            :         result = 1;
     611                 :            : 
     612                 :          1 :         read_lock(&journal->j_state_lock);
     613                 :            : 
     614                 :            :         /* Don't extend a locked-down transaction! */
     615                 :          1 :         if (transaction->t_state != T_RUNNING) {
     616                 :            :                 jbd_debug(3, "denied handle %p %d blocks: "
     617                 :            :                           "transaction not running\n", handle, nblocks);
     618                 :            :                 goto error_out;
     619                 :            :         }
     620                 :            : 
     621                 :            :         spin_lock(&transaction->t_handle_lock);
     622                 :          1 :         wanted = atomic_add_return(nblocks,
     623                 :            :                                    &transaction->t_outstanding_credits);
     624                 :            : 
     625                 :          1 :         if (wanted > journal->j_max_transaction_buffers) {
     626                 :            :                 jbd_debug(3, "denied handle %p %d blocks: "
     627                 :            :                           "transaction too large\n", handle, nblocks);
     628                 :            :                 atomic_sub(nblocks, &transaction->t_outstanding_credits);
     629                 :            :                 goto unlock;
     630                 :            :         }
     631                 :            : 
     632                 :          1 :         if (wanted + (wanted >> JBD2_CONTROL_BLOCKS_SHIFT) >
     633                 :            :             jbd2_log_space_left(journal)) {
     634                 :            :                 jbd_debug(3, "denied handle %p %d blocks: "
     635                 :            :                           "insufficient log space\n", handle, nblocks);
     636                 :            :                 atomic_sub(nblocks, &transaction->t_outstanding_credits);
     637                 :            :                 goto unlock;
     638                 :            :         }
     639                 :            : 
     640                 :          1 :         trace_jbd2_handle_extend(journal->j_fs_dev->bd_dev,
     641                 :          1 :                                  transaction->t_tid,
     642                 :          1 :                                  handle->h_type, handle->h_line_no,
     643                 :            :                                  handle->h_buffer_credits,
     644                 :            :                                  nblocks);
     645                 :            : 
     646                 :          1 :         handle->h_buffer_credits += nblocks;
     647                 :          1 :         handle->h_requested_credits += nblocks;
     648                 :            :         result = 0;
     649                 :            : 
     650                 :            :         jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
     651                 :            : unlock:
     652                 :            :         spin_unlock(&transaction->t_handle_lock);
     653                 :            : error_out:
     654                 :            :         read_unlock(&journal->j_state_lock);
     655                 :          1 :         return result;
     656                 :            : }
     657                 :            : 
     658                 :            : 
     659                 :            : /**
     660                 :            :  * int jbd2_journal_restart() - restart a handle .
     661                 :            :  * @handle:  handle to restart
     662                 :            :  * @nblocks: nr credits requested
     663                 :            :  * @gfp_mask: memory allocation flags (for start_this_handle)
     664                 :            :  *
     665                 :            :  * Restart a handle for a multi-transaction filesystem
     666                 :            :  * operation.
     667                 :            :  *
     668                 :            :  * If the jbd2_journal_extend() call above fails to grant new buffer credits
     669                 :            :  * to a running handle, a call to jbd2_journal_restart will commit the
     670                 :            :  * handle's transaction so far and reattach the handle to a new
     671                 :            :  * transaction capable of guaranteeing the requested number of
     672                 :            :  * credits. We preserve reserved handle if there's any attached to the
     673                 :            :  * passed in handle.
     674                 :            :  */
     675                 :          0 : int jbd2__journal_restart(handle_t *handle, int nblocks, gfp_t gfp_mask)
     676                 :            : {
     677                 :          0 :         transaction_t *transaction = handle->h_transaction;
     678                 :            :         journal_t *journal;
     679                 :            :         tid_t           tid;
     680                 :            :         int             need_to_start, ret;
     681                 :            : 
     682                 :            :         /* If we've had an abort of any type, don't even think about
     683                 :            :          * actually doing the restart! */
     684                 :          0 :         if (is_handle_aborted(handle))
     685                 :            :                 return 0;
     686                 :          0 :         journal = transaction->t_journal;
     687                 :            : 
     688                 :            :         /*
     689                 :            :          * First unlink the handle from its current transaction, and start the
     690                 :            :          * commit on that.
     691                 :            :          */
     692                 :          0 :         J_ASSERT(atomic_read(&transaction->t_updates) > 0);
     693                 :          0 :         J_ASSERT(journal_current_handle() == handle);
     694                 :            : 
     695                 :          0 :         read_lock(&journal->j_state_lock);
     696                 :            :         spin_lock(&transaction->t_handle_lock);
     697                 :          0 :         atomic_sub(handle->h_buffer_credits,
     698                 :            :                    &transaction->t_outstanding_credits);
     699                 :          0 :         if (handle->h_rsv_handle) {
     700                 :          0 :                 sub_reserved_credits(journal,
     701                 :            :                                      handle->h_rsv_handle->h_buffer_credits);
     702                 :            :         }
     703                 :          0 :         if (atomic_dec_and_test(&transaction->t_updates))
     704                 :          0 :                 wake_up(&journal->j_wait_updates);
     705                 :          0 :         tid = transaction->t_tid;
     706                 :            :         spin_unlock(&transaction->t_handle_lock);
     707                 :          0 :         handle->h_transaction = NULL;
     708                 :          0 :         current->journal_info = NULL;
     709                 :            : 
     710                 :            :         jbd_debug(2, "restarting handle %p\n", handle);
     711                 :          0 :         need_to_start = !tid_geq(journal->j_commit_request, tid);
     712                 :            :         read_unlock(&journal->j_state_lock);
     713                 :          0 :         if (need_to_start)
     714                 :          0 :                 jbd2_log_start_commit(journal, tid);
     715                 :            : 
     716                 :            :         rwsem_release(&journal->j_trans_commit_map, 1, _THIS_IP_);
     717                 :          0 :         handle->h_buffer_credits = nblocks;
     718                 :            :         /*
     719                 :            :          * Restore the original nofs context because the journal restart
     720                 :            :          * is basically the same thing as journal stop and start.
     721                 :            :          * start_this_handle will start a new nofs context.
     722                 :            :          */
     723                 :          0 :         memalloc_nofs_restore(handle->saved_alloc_context);
     724                 :          0 :         ret = start_this_handle(journal, handle, gfp_mask);
     725                 :          0 :         return ret;
     726                 :            : }
     727                 :            : EXPORT_SYMBOL(jbd2__journal_restart);
     728                 :            : 
     729                 :            : 
     730                 :          0 : int jbd2_journal_restart(handle_t *handle, int nblocks)
     731                 :            : {
     732                 :          0 :         return jbd2__journal_restart(handle, nblocks, GFP_NOFS);
     733                 :            : }
     734                 :            : EXPORT_SYMBOL(jbd2_journal_restart);
     735                 :            : 
     736                 :            : /**
     737                 :            :  * void jbd2_journal_lock_updates () - establish a transaction barrier.
     738                 :            :  * @journal:  Journal to establish a barrier on.
     739                 :            :  *
     740                 :            :  * This locks out any further updates from being started, and blocks
     741                 :            :  * until all existing updates have completed, returning only once the
     742                 :            :  * journal is in a quiescent state with no updates running.
     743                 :            :  *
     744                 :            :  * The journal lock should not be held on entry.
     745                 :            :  */
     746                 :          1 : void jbd2_journal_lock_updates(journal_t *journal)
     747                 :            : {
     748                 :          1 :         DEFINE_WAIT(wait);
     749                 :            : 
     750                 :            :         jbd2_might_wait_for_commit(journal);
     751                 :            : 
     752                 :          1 :         write_lock(&journal->j_state_lock);
     753                 :          1 :         ++journal->j_barrier_count;
     754                 :            : 
     755                 :            :         /* Wait until there are no reserved handles */
     756                 :          1 :         if (atomic_read(&journal->j_reserved_credits)) {
     757                 :            :                 write_unlock(&journal->j_state_lock);
     758                 :          0 :                 wait_event(journal->j_wait_reserved,
     759                 :            :                            atomic_read(&journal->j_reserved_credits) == 0);
     760                 :          0 :                 write_lock(&journal->j_state_lock);
     761                 :            :         }
     762                 :            : 
     763                 :            :         /* Wait until there are no running updates */
     764                 :            :         while (1) {
     765                 :          1 :                 transaction_t *transaction = journal->j_running_transaction;
     766                 :            : 
     767                 :          1 :                 if (!transaction)
     768                 :            :                         break;
     769                 :            : 
     770                 :            :                 spin_lock(&transaction->t_handle_lock);
     771                 :          0 :                 prepare_to_wait(&journal->j_wait_updates, &wait,
     772                 :            :                                 TASK_UNINTERRUPTIBLE);
     773                 :          0 :                 if (!atomic_read(&transaction->t_updates)) {
     774                 :            :                         spin_unlock(&transaction->t_handle_lock);
     775                 :          0 :                         finish_wait(&journal->j_wait_updates, &wait);
     776                 :          0 :                         break;
     777                 :            :                 }
     778                 :            :                 spin_unlock(&transaction->t_handle_lock);
     779                 :            :                 write_unlock(&journal->j_state_lock);
     780                 :          0 :                 schedule();
     781                 :          0 :                 finish_wait(&journal->j_wait_updates, &wait);
     782                 :          0 :                 write_lock(&journal->j_state_lock);
     783                 :          0 :         }
     784                 :            :         write_unlock(&journal->j_state_lock);
     785                 :            : 
     786                 :            :         /*
     787                 :            :          * We have now established a barrier against other normal updates, but
     788                 :            :          * we also need to barrier against other jbd2_journal_lock_updates() calls
     789                 :            :          * to make sure that we serialise special journal-locked operations
     790                 :            :          * too.
     791                 :            :          */
     792                 :          1 :         mutex_lock(&journal->j_barrier);
     793                 :          1 : }
     794                 :            : 
     795                 :            : /**
     796                 :            :  * void jbd2_journal_unlock_updates (journal_t* journal) - release barrier
     797                 :            :  * @journal:  Journal to release the barrier on.
     798                 :            :  *
     799                 :            :  * Release a transaction barrier obtained with jbd2_journal_lock_updates().
     800                 :            :  *
     801                 :            :  * Should be called without the journal lock held.
     802                 :            :  */
     803                 :          1 : void jbd2_journal_unlock_updates (journal_t *journal)
     804                 :            : {
     805                 :          1 :         J_ASSERT(journal->j_barrier_count != 0);
     806                 :            : 
     807                 :          1 :         mutex_unlock(&journal->j_barrier);
     808                 :          1 :         write_lock(&journal->j_state_lock);
     809                 :          1 :         --journal->j_barrier_count;
     810                 :            :         write_unlock(&journal->j_state_lock);
     811                 :          1 :         wake_up(&journal->j_wait_transaction_locked);
     812                 :          1 : }
     813                 :            : 
     814                 :            : static void warn_dirty_buffer(struct buffer_head *bh)
     815                 :            : {
     816                 :          0 :         printk(KERN_WARNING
     817                 :            :                "JBD2: Spotted dirty metadata buffer (dev = %pg, blocknr = %llu). "
     818                 :            :                "There's a risk of filesystem corruption in case of system "
     819                 :            :                "crash.\n",
     820                 :            :                bh->b_bdev, (unsigned long long)bh->b_blocknr);
     821                 :            : }
     822                 :            : 
     823                 :            : /* Call t_frozen trigger and copy buffer data into jh->b_frozen_data. */
     824                 :          3 : static void jbd2_freeze_jh_data(struct journal_head *jh)
     825                 :            : {
     826                 :            :         struct page *page;
     827                 :            :         int offset;
     828                 :            :         char *source;
     829                 :            :         struct buffer_head *bh = jh2bh(jh);
     830                 :            : 
     831                 :          3 :         J_EXPECT_JH(jh, buffer_uptodate(bh), "Possible IO failure.\n");
     832                 :          3 :         page = bh->b_page;
     833                 :          3 :         offset = offset_in_page(bh->b_data);
     834                 :          3 :         source = kmap_atomic(page);
     835                 :            :         /* Fire data frozen trigger just before we copy the data */
     836                 :          3 :         jbd2_buffer_frozen_trigger(jh, source + offset, jh->b_triggers);
     837                 :          3 :         memcpy(jh->b_frozen_data, source + offset, bh->b_size);
     838                 :            :         kunmap_atomic(source);
     839                 :            : 
     840                 :            :         /*
     841                 :            :          * Now that the frozen data is saved off, we need to store any matching
     842                 :            :          * triggers.
     843                 :            :          */
     844                 :          3 :         jh->b_frozen_triggers = jh->b_triggers;
     845                 :          3 : }
     846                 :            : 
     847                 :            : /*
     848                 :            :  * If the buffer is already part of the current transaction, then there
     849                 :            :  * is nothing we need to do.  If it is already part of a prior
     850                 :            :  * transaction which we are still committing to disk, then we need to
     851                 :            :  * make sure that we do not overwrite the old copy: we do copy-out to
     852                 :            :  * preserve the copy going to disk.  We also account the buffer against
     853                 :            :  * the handle's metadata buffer credits (unless the buffer is already
     854                 :            :  * part of the transaction, that is).
     855                 :            :  *
     856                 :            :  */
     857                 :            : static int
     858                 :          3 : do_get_write_access(handle_t *handle, struct journal_head *jh,
     859                 :            :                         int force_copy)
     860                 :            : {
     861                 :            :         struct buffer_head *bh;
     862                 :          3 :         transaction_t *transaction = handle->h_transaction;
     863                 :            :         journal_t *journal;
     864                 :            :         int error;
     865                 :            :         char *frozen_buffer = NULL;
     866                 :            :         unsigned long start_lock, time_lock;
     867                 :            : 
     868                 :          3 :         journal = transaction->t_journal;
     869                 :            : 
     870                 :            :         jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);
     871                 :            : 
     872                 :            :         JBUFFER_TRACE(jh, "entry");
     873                 :            : repeat:
     874                 :            :         bh = jh2bh(jh);
     875                 :            : 
     876                 :            :         /* @@@ Need to check for errors here at some point. */
     877                 :            : 
     878                 :          3 :         start_lock = jiffies;
     879                 :          3 :         lock_buffer(bh);
     880                 :            :         jbd_lock_bh_state(bh);
     881                 :            : 
     882                 :            :         /* If it takes too long to lock the buffer, trace it */
     883                 :          3 :         time_lock = jbd2_time_diff(start_lock, jiffies);
     884                 :          3 :         if (time_lock > HZ/10)
     885                 :          3 :                 trace_jbd2_lock_buffer_stall(bh->b_bdev->bd_dev,
     886                 :          3 :                         jiffies_to_msecs(time_lock));
     887                 :            : 
     888                 :            :         /* We now hold the buffer lock so it is safe to query the buffer
     889                 :            :          * state.  Is the buffer dirty?
     890                 :            :          *
     891                 :            :          * If so, there are two possibilities.  The buffer may be
     892                 :            :          * non-journaled, and undergoing a quite legitimate writeback.
     893                 :            :          * Otherwise, it is journaled, and we don't expect dirty buffers
     894                 :            :          * in that state (the buffers should be marked JBD_Dirty
     895                 :            :          * instead.)  So either the IO is being done under our own
     896                 :            :          * control and this is a bug, or it's a third party IO such as
     897                 :            :          * dump(8) (which may leave the buffer scheduled for read ---
     898                 :            :          * ie. locked but not dirty) or tune2fs (which may actually have
     899                 :            :          * the buffer dirtied, ugh.)  */
     900                 :            : 
     901                 :          3 :         if (buffer_dirty(bh)) {
     902                 :            :                 /*
     903                 :            :                  * First question: is this buffer already part of the current
     904                 :            :                  * transaction or the existing committing transaction?
     905                 :            :                  */
     906                 :          3 :                 if (jh->b_transaction) {
     907                 :          0 :                         J_ASSERT_JH(jh,
     908                 :            :                                 jh->b_transaction == transaction ||
     909                 :            :                                 jh->b_transaction ==
     910                 :            :                                         journal->j_committing_transaction);
     911                 :          0 :                         if (jh->b_next_transaction)
     912                 :          0 :                                 J_ASSERT_JH(jh, jh->b_next_transaction ==
     913                 :            :                                                         transaction);
     914                 :            :                         warn_dirty_buffer(bh);
     915                 :            :                 }
     916                 :            :                 /*
     917                 :            :                  * In any case we need to clean the dirty flag and we must
     918                 :            :                  * do it under the buffer lock to be sure we don't race
     919                 :            :                  * with running write-out.
     920                 :            :                  */
     921                 :            :                 JBUFFER_TRACE(jh, "Journalling dirty buffer");
     922                 :            :                 clear_buffer_dirty(bh);
     923                 :            :                 set_buffer_jbddirty(bh);
     924                 :            :         }
     925                 :            : 
     926                 :          3 :         unlock_buffer(bh);
     927                 :            : 
     928                 :            :         error = -EROFS;
     929                 :          3 :         if (is_handle_aborted(handle)) {
     930                 :            :                 jbd_unlock_bh_state(bh);
     931                 :            :                 goto out;
     932                 :            :         }
     933                 :            :         error = 0;
     934                 :            : 
     935                 :            :         /*
     936                 :            :          * The buffer is already part of this transaction if b_transaction or
     937                 :            :          * b_next_transaction points to it
     938                 :            :          */
     939                 :          3 :         if (jh->b_transaction == transaction ||
     940                 :          3 :             jh->b_next_transaction == transaction)
     941                 :            :                 goto done;
     942                 :            : 
     943                 :            :         /*
     944                 :            :          * this is the first time this transaction is touching this buffer,
     945                 :            :          * reset the modified flag
     946                 :            :          */
     947                 :          3 :         jh->b_modified = 0;
     948                 :            : 
     949                 :            :         /*
     950                 :            :          * If the buffer is not journaled right now, we need to make sure it
     951                 :            :          * doesn't get written to disk before the caller actually commits the
     952                 :            :          * new data
     953                 :            :          */
     954                 :          3 :         if (!jh->b_transaction) {
     955                 :            :                 JBUFFER_TRACE(jh, "no transaction");
     956                 :          3 :                 J_ASSERT_JH(jh, !jh->b_next_transaction);
     957                 :            :                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
     958                 :            :                 /*
     959                 :            :                  * Make sure all stores to jh (b_modified, b_frozen_data) are
     960                 :            :                  * visible before attaching it to the running transaction.
     961                 :            :                  * Paired with barrier in jbd2_write_access_granted()
     962                 :            :                  */
     963                 :          3 :                 smp_wmb();
     964                 :            :                 spin_lock(&journal->j_list_lock);
     965                 :          3 :                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
     966                 :            :                 spin_unlock(&journal->j_list_lock);
     967                 :            :                 goto done;
     968                 :            :         }
     969                 :            :         /*
     970                 :            :          * If there is already a copy-out version of this buffer, then we don't
     971                 :            :          * need to make another one
     972                 :            :          */
     973                 :          3 :         if (jh->b_frozen_data) {
     974                 :            :                 JBUFFER_TRACE(jh, "has frozen data");
     975                 :          0 :                 J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
     976                 :            :                 goto attach_next;
     977                 :            :         }
     978                 :            : 
     979                 :            :         JBUFFER_TRACE(jh, "owned by older transaction");
     980                 :          3 :         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
     981                 :          3 :         J_ASSERT_JH(jh, jh->b_transaction == journal->j_committing_transaction);
     982                 :            : 
     983                 :            :         /*
     984                 :            :          * There is one case we have to be very careful about.  If the
     985                 :            :          * committing transaction is currently writing this buffer out to disk
     986                 :            :          * and has NOT made a copy-out, then we cannot modify the buffer
     987                 :            :          * contents at all right now.  The essence of copy-out is that it is
     988                 :            :          * the extra copy, not the primary copy, which gets journaled.  If the
     989                 :            :          * primary copy is already going to disk then we cannot do copy-out
     990                 :            :          * here.
     991                 :            :          */
     992                 :          3 :         if (buffer_shadow(bh)) {
     993                 :            :                 JBUFFER_TRACE(jh, "on shadow: sleep");
     994                 :            :                 jbd_unlock_bh_state(bh);
     995                 :          3 :                 wait_on_bit_io(&bh->b_state, BH_Shadow, TASK_UNINTERRUPTIBLE);
     996                 :          3 :                 goto repeat;
     997                 :            :         }
     998                 :            : 
     999                 :            :         /*
    1000                 :            :          * Only do the copy if the currently-owning transaction still needs it.
    1001                 :            :          * If buffer isn't on BJ_Metadata list, the committing transaction is
    1002                 :            :          * past that stage (here we use the fact that BH_Shadow is set under
    1003                 :            :          * bh_state lock together with refiling to BJ_Shadow list and at this
    1004                 :            :          * point we know the buffer doesn't have BH_Shadow set).
    1005                 :            :          *
    1006                 :            :          * Subtle point, though: if this is a get_undo_access, then we will be
    1007                 :            :          * relying on the frozen_data to contain the new value of the
    1008                 :            :          * committed_data record after the transaction, so we HAVE to force the
    1009                 :            :          * frozen_data copy in that case.
    1010                 :            :          */
    1011                 :          3 :         if (jh->b_jlist == BJ_Metadata || force_copy) {
    1012                 :            :                 JBUFFER_TRACE(jh, "generate frozen data");
    1013                 :          3 :                 if (!frozen_buffer) {
    1014                 :            :                         JBUFFER_TRACE(jh, "allocate memory for buffer");
    1015                 :            :                         jbd_unlock_bh_state(bh);
    1016                 :          3 :                         frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
    1017                 :            :                                                    GFP_NOFS | __GFP_NOFAIL);
    1018                 :          3 :                         goto repeat;
    1019                 :            :                 }
    1020                 :          3 :                 jh->b_frozen_data = frozen_buffer;
    1021                 :            :                 frozen_buffer = NULL;
    1022                 :          3 :                 jbd2_freeze_jh_data(jh);
    1023                 :            :         }
    1024                 :            : attach_next:
    1025                 :            :         /*
    1026                 :            :          * Make sure all stores to jh (b_modified, b_frozen_data) are visible
    1027                 :            :          * before attaching it to the running transaction. Paired with barrier
    1028                 :            :          * in jbd2_write_access_granted()
    1029                 :            :          */
    1030                 :          3 :         smp_wmb();
    1031                 :          3 :         jh->b_next_transaction = transaction;
    1032                 :            : 
    1033                 :            : done:
    1034                 :            :         jbd_unlock_bh_state(bh);
    1035                 :            : 
    1036                 :            :         /*
    1037                 :            :          * If we are about to journal a buffer, then any revoke pending on it is
    1038                 :            :          * no longer valid
    1039                 :            :          */
    1040                 :          3 :         jbd2_journal_cancel_revoke(handle, jh);
    1041                 :            : 
    1042                 :            : out:
    1043                 :          3 :         if (unlikely(frozen_buffer))    /* It's usually NULL */
    1044                 :          3 :                 jbd2_free(frozen_buffer, bh->b_size);
    1045                 :            : 
    1046                 :            :         JBUFFER_TRACE(jh, "exit");
    1047                 :          3 :         return error;
    1048                 :            : }
    1049                 :            : 
    1050                 :            : /* Fast check whether buffer is already attached to the required transaction */
    1051                 :          3 : static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh,
    1052                 :            :                                                         bool undo)
    1053                 :            : {
    1054                 :            :         struct journal_head *jh;
    1055                 :            :         bool ret = false;
    1056                 :            : 
    1057                 :            :         /* Dirty buffers require special handling... */
    1058                 :          3 :         if (buffer_dirty(bh))
    1059                 :            :                 return false;
    1060                 :            : 
    1061                 :            :         /*
    1062                 :            :          * RCU protects us from dereferencing freed pages. So the checks we do
    1063                 :            :          * are guaranteed not to oops. However the jh slab object can get freed
    1064                 :            :          * & reallocated while we work with it. So we have to be careful. When
    1065                 :            :          * we see jh attached to the running transaction, we know it must stay
    1066                 :            :          * so until the transaction is committed. Thus jh won't be freed and
    1067                 :            :          * will be attached to the same bh while we run.  However it can
    1068                 :            :          * happen jh gets freed, reallocated, and attached to the transaction
    1069                 :            :          * just after we get pointer to it from bh. So we have to be careful
    1070                 :            :          * and recheck jh still belongs to our bh before we return success.
    1071                 :            :          */
    1072                 :            :         rcu_read_lock();
    1073                 :          3 :         if (!buffer_jbd(bh))
    1074                 :            :                 goto out;
    1075                 :            :         /* This should be bh2jh() but that doesn't work with inline functions */
    1076                 :            :         jh = READ_ONCE(bh->b_private);
    1077                 :          3 :         if (!jh)
    1078                 :            :                 goto out;
    1079                 :            :         /* For undo access buffer must have data copied */
    1080                 :          3 :         if (undo && !jh->b_committed_data)
    1081                 :            :                 goto out;
    1082                 :          3 :         if (READ_ONCE(jh->b_transaction) != handle->h_transaction &&
    1083                 :          3 :             READ_ONCE(jh->b_next_transaction) != handle->h_transaction)
    1084                 :            :                 goto out;
    1085                 :            :         /*
    1086                 :            :          * There are two reasons for the barrier here:
    1087                 :            :          * 1) Make sure to fetch b_bh after we did previous checks so that we
    1088                 :            :          * detect when jh went through free, realloc, attach to transaction
    1089                 :            :          * while we were checking. Paired with implicit barrier in that path.
    1090                 :            :          * 2) So that access to bh done after jbd2_write_access_granted()
    1091                 :            :          * doesn't get reordered and see inconsistent state of concurrent
    1092                 :            :          * do_get_write_access().
    1093                 :            :          */
    1094                 :          3 :         smp_mb();
    1095                 :          3 :         if (unlikely(jh->b_bh != bh))
    1096                 :            :                 goto out;
    1097                 :            :         ret = true;
    1098                 :            : out:
    1099                 :            :         rcu_read_unlock();
    1100                 :          3 :         return ret;
    1101                 :            : }
    1102                 :            : 
    1103                 :            : /**
    1104                 :            :  * int jbd2_journal_get_write_access() - notify intent to modify a buffer for metadata (not data) update.
    1105                 :            :  * @handle: transaction to add buffer modifications to
    1106                 :            :  * @bh:     bh to be used for metadata writes
    1107                 :            :  *
    1108                 :            :  * Returns: error code or 0 on success.
    1109                 :            :  *
    1110                 :            :  * In full data journalling mode the buffer may be of type BJ_AsyncData,
    1111                 :            :  * because we're ``write()ing`` a buffer which is also part of a shared mapping.
    1112                 :            :  */
    1113                 :            : 
    1114                 :          3 : int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
    1115                 :            : {
    1116                 :            :         struct journal_head *jh;
    1117                 :            :         int rc;
    1118                 :            : 
    1119                 :          3 :         if (is_handle_aborted(handle))
    1120                 :            :                 return -EROFS;
    1121                 :            : 
    1122                 :          3 :         if (jbd2_write_access_granted(handle, bh, false))
    1123                 :            :                 return 0;
    1124                 :            : 
    1125                 :          3 :         jh = jbd2_journal_add_journal_head(bh);
    1126                 :            :         /* We do not want to get caught playing with fields which the
    1127                 :            :          * log thread also manipulates.  Make sure that the buffer
    1128                 :            :          * completes any outstanding IO before proceeding. */
    1129                 :          3 :         rc = do_get_write_access(handle, jh, 0);
    1130                 :          3 :         jbd2_journal_put_journal_head(jh);
    1131                 :          3 :         return rc;
    1132                 :            : }
    1133                 :            : 
    1134                 :            : 
    1135                 :            : /*
    1136                 :            :  * When the user wants to journal a newly created buffer_head
    1137                 :            :  * (ie. getblk() returned a new buffer and we are going to populate it
    1138                 :            :  * manually rather than reading off disk), then we need to keep the
    1139                 :            :  * buffer_head locked until it has been completely filled with new
    1140                 :            :  * data.  In this case, we should be able to make the assertion that
    1141                 :            :  * the bh is not already part of an existing transaction.
    1142                 :            :  *
    1143                 :            :  * The buffer should already be locked by the caller by this point.
    1144                 :            :  * There is no lock ranking violation: it was a newly created,
    1145                 :            :  * unlocked buffer beforehand. */
    1146                 :            : 
    1147                 :            : /**
    1148                 :            :  * int jbd2_journal_get_create_access () - notify intent to use newly created bh
    1149                 :            :  * @handle: transaction to new buffer to
    1150                 :            :  * @bh: new buffer.
    1151                 :            :  *
    1152                 :            :  * Call this if you create a new bh.
    1153                 :            :  */
    1154                 :          3 : int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
    1155                 :            : {
    1156                 :          3 :         transaction_t *transaction = handle->h_transaction;
    1157                 :            :         journal_t *journal;
    1158                 :          3 :         struct journal_head *jh = jbd2_journal_add_journal_head(bh);
    1159                 :            :         int err;
    1160                 :            : 
    1161                 :            :         jbd_debug(5, "journal_head %p\n", jh);
    1162                 :            :         err = -EROFS;
    1163                 :          3 :         if (is_handle_aborted(handle))
    1164                 :            :                 goto out;
    1165                 :          3 :         journal = transaction->t_journal;
    1166                 :            :         err = 0;
    1167                 :            : 
    1168                 :            :         JBUFFER_TRACE(jh, "entry");
    1169                 :            :         /*
    1170                 :            :          * The buffer may already belong to this transaction due to pre-zeroing
    1171                 :            :          * in the filesystem's new_block code.  It may also be on the previous,
    1172                 :            :          * committing transaction's lists, but it HAS to be in Forget state in
    1173                 :            :          * that case: the transaction must have deleted the buffer for it to be
    1174                 :            :          * reused here.
    1175                 :            :          */
    1176                 :            :         jbd_lock_bh_state(bh);
    1177                 :          3 :         J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
    1178                 :            :                 jh->b_transaction == NULL ||
    1179                 :            :                 (jh->b_transaction == journal->j_committing_transaction &&
    1180                 :            :                           jh->b_jlist == BJ_Forget)));
    1181                 :            : 
    1182                 :          3 :         J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
    1183                 :          3 :         J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));
    1184                 :            : 
    1185                 :          3 :         if (jh->b_transaction == NULL) {
    1186                 :            :                 /*
    1187                 :            :                  * Previous jbd2_journal_forget() could have left the buffer
    1188                 :            :                  * with jbddirty bit set because it was being committed. When
    1189                 :            :                  * the commit finished, we've filed the buffer for
    1190                 :            :                  * checkpointing and marked it dirty. Now we are reallocating
    1191                 :            :                  * the buffer so the transaction freeing it must have
    1192                 :            :                  * committed and so it's safe to clear the dirty bit.
    1193                 :            :                  */
    1194                 :            :                 clear_buffer_dirty(jh2bh(jh));
    1195                 :            :                 /* first access by this transaction */
    1196                 :          3 :                 jh->b_modified = 0;
    1197                 :            : 
    1198                 :            :                 JBUFFER_TRACE(jh, "file as BJ_Reserved");
    1199                 :            :                 spin_lock(&journal->j_list_lock);
    1200                 :          3 :                 __jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
    1201                 :            :                 spin_unlock(&journal->j_list_lock);
    1202                 :          0 :         } else if (jh->b_transaction == journal->j_committing_transaction) {
    1203                 :            :                 /* first access by this transaction */
    1204                 :          0 :                 jh->b_modified = 0;
    1205                 :            : 
    1206                 :            :                 JBUFFER_TRACE(jh, "set next transaction");
    1207                 :            :                 spin_lock(&journal->j_list_lock);
    1208                 :          0 :                 jh->b_next_transaction = transaction;
    1209                 :            :                 spin_unlock(&journal->j_list_lock);
    1210                 :            :         }
    1211                 :            :         jbd_unlock_bh_state(bh);
    1212                 :            : 
    1213                 :            :         /*
    1214                 :            :          * akpm: I added this.  ext3_alloc_branch can pick up new indirect
    1215                 :            :          * blocks which contain freed but then revoked metadata.  We need
    1216                 :            :          * to cancel the revoke in case we end up freeing it yet again
    1217                 :            :          * and the reallocating as data - this would cause a second revoke,
    1218                 :            :          * which hits an assertion error.
    1219                 :            :          */
    1220                 :            :         JBUFFER_TRACE(jh, "cancelling revoke");
    1221                 :          3 :         jbd2_journal_cancel_revoke(handle, jh);
    1222                 :            : out:
    1223                 :          3 :         jbd2_journal_put_journal_head(jh);
    1224                 :          3 :         return err;
    1225                 :            : }
    1226                 :            : 
    1227                 :            : /**
    1228                 :            :  * int jbd2_journal_get_undo_access() -  Notify intent to modify metadata with
    1229                 :            :  *     non-rewindable consequences
    1230                 :            :  * @handle: transaction
    1231                 :            :  * @bh: buffer to undo
    1232                 :            :  *
    1233                 :            :  * Sometimes there is a need to distinguish between metadata which has
    1234                 :            :  * been committed to disk and that which has not.  The ext3fs code uses
    1235                 :            :  * this for freeing and allocating space, we have to make sure that we
    1236                 :            :  * do not reuse freed space until the deallocation has been committed,
    1237                 :            :  * since if we overwrote that space we would make the delete
    1238                 :            :  * un-rewindable in case of a crash.
    1239                 :            :  *
    1240                 :            :  * To deal with that, jbd2_journal_get_undo_access requests write access to a
    1241                 :            :  * buffer for parts of non-rewindable operations such as delete
    1242                 :            :  * operations on the bitmaps.  The journaling code must keep a copy of
    1243                 :            :  * the buffer's contents prior to the undo_access call until such time
    1244                 :            :  * as we know that the buffer has definitely been committed to disk.
    1245                 :            :  *
    1246                 :            :  * We never need to know which transaction the committed data is part
    1247                 :            :  * of, buffers touched here are guaranteed to be dirtied later and so
    1248                 :            :  * will be committed to a new transaction in due course, at which point
    1249                 :            :  * we can discard the old committed data pointer.
    1250                 :            :  *
    1251                 :            :  * Returns error number or 0 on success.
    1252                 :            :  */
    1253                 :          0 : int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
    1254                 :            : {
    1255                 :            :         int err;
    1256                 :            :         struct journal_head *jh;
    1257                 :            :         char *committed_data = NULL;
    1258                 :            : 
    1259                 :          0 :         if (is_handle_aborted(handle))
    1260                 :            :                 return -EROFS;
    1261                 :            : 
    1262                 :          0 :         if (jbd2_write_access_granted(handle, bh, true))
    1263                 :            :                 return 0;
    1264                 :            : 
    1265                 :          0 :         jh = jbd2_journal_add_journal_head(bh);
    1266                 :            :         JBUFFER_TRACE(jh, "entry");
    1267                 :            : 
    1268                 :            :         /*
    1269                 :            :          * Do this first --- it can drop the journal lock, so we want to
    1270                 :            :          * make sure that obtaining the committed_data is done
    1271                 :            :          * atomically wrt. completion of any outstanding commits.
    1272                 :            :          */
    1273                 :          0 :         err = do_get_write_access(handle, jh, 1);
    1274                 :          0 :         if (err)
    1275                 :            :                 goto out;
    1276                 :            : 
    1277                 :            : repeat:
    1278                 :          0 :         if (!jh->b_committed_data)
    1279                 :          0 :                 committed_data = jbd2_alloc(jh2bh(jh)->b_size,
    1280                 :            :                                             GFP_NOFS|__GFP_NOFAIL);
    1281                 :            : 
    1282                 :            :         jbd_lock_bh_state(bh);
    1283                 :          0 :         if (!jh->b_committed_data) {
    1284                 :            :                 /* Copy out the current buffer contents into the
    1285                 :            :                  * preserved, committed copy. */
    1286                 :            :                 JBUFFER_TRACE(jh, "generate b_committed data");
    1287                 :          0 :                 if (!committed_data) {
    1288                 :            :                         jbd_unlock_bh_state(bh);
    1289                 :            :                         goto repeat;
    1290                 :            :                 }
    1291                 :            : 
    1292                 :          0 :                 jh->b_committed_data = committed_data;
    1293                 :            :                 committed_data = NULL;
    1294                 :          0 :                 memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
    1295                 :            :         }
    1296                 :            :         jbd_unlock_bh_state(bh);
    1297                 :            : out:
    1298                 :          0 :         jbd2_journal_put_journal_head(jh);
    1299                 :          0 :         if (unlikely(committed_data))
    1300                 :          0 :                 jbd2_free(committed_data, bh->b_size);
    1301                 :          0 :         return err;
    1302                 :            : }
    1303                 :            : 
    1304                 :            : /**
    1305                 :            :  * void jbd2_journal_set_triggers() - Add triggers for commit writeout
    1306                 :            :  * @bh: buffer to trigger on
    1307                 :            :  * @type: struct jbd2_buffer_trigger_type containing the trigger(s).
    1308                 :            :  *
    1309                 :            :  * Set any triggers on this journal_head.  This is always safe, because
    1310                 :            :  * triggers for a committing buffer will be saved off, and triggers for
    1311                 :            :  * a running transaction will match the buffer in that transaction.
    1312                 :            :  *
    1313                 :            :  * Call with NULL to clear the triggers.
    1314                 :            :  */
    1315                 :          0 : void jbd2_journal_set_triggers(struct buffer_head *bh,
    1316                 :            :                                struct jbd2_buffer_trigger_type *type)
    1317                 :            : {
    1318                 :          0 :         struct journal_head *jh = jbd2_journal_grab_journal_head(bh);
    1319                 :            : 
    1320                 :          0 :         if (WARN_ON(!jh))
    1321                 :          0 :                 return;
    1322                 :          0 :         jh->b_triggers = type;
    1323                 :          0 :         jbd2_journal_put_journal_head(jh);
    1324                 :            : }
    1325                 :            : 
    1326                 :          3 : void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
    1327                 :            :                                 struct jbd2_buffer_trigger_type *triggers)
    1328                 :            : {
    1329                 :            :         struct buffer_head *bh = jh2bh(jh);
    1330                 :            : 
    1331                 :          3 :         if (!triggers || !triggers->t_frozen)
    1332                 :          3 :                 return;
    1333                 :            : 
    1334                 :          0 :         triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
    1335                 :            : }
    1336                 :            : 
    1337                 :          0 : void jbd2_buffer_abort_trigger(struct journal_head *jh,
    1338                 :            :                                struct jbd2_buffer_trigger_type *triggers)
    1339                 :            : {
    1340                 :          0 :         if (!triggers || !triggers->t_abort)
    1341                 :          0 :                 return;
    1342                 :            : 
    1343                 :          0 :         triggers->t_abort(triggers, jh2bh(jh));
    1344                 :            : }
    1345                 :            : 
    1346                 :            : /**
    1347                 :            :  * int jbd2_journal_dirty_metadata() -  mark a buffer as containing dirty metadata
    1348                 :            :  * @handle: transaction to add buffer to.
    1349                 :            :  * @bh: buffer to mark
    1350                 :            :  *
    1351                 :            :  * mark dirty metadata which needs to be journaled as part of the current
    1352                 :            :  * transaction.
    1353                 :            :  *
    1354                 :            :  * The buffer must have previously had jbd2_journal_get_write_access()
    1355                 :            :  * called so that it has a valid journal_head attached to the buffer
    1356                 :            :  * head.
    1357                 :            :  *
    1358                 :            :  * The buffer is placed on the transaction's metadata list and is marked
    1359                 :            :  * as belonging to the transaction.
    1360                 :            :  *
    1361                 :            :  * Returns error number or 0 on success.
    1362                 :            :  *
    1363                 :            :  * Special care needs to be taken if the buffer already belongs to the
    1364                 :            :  * current committing transaction (in which case we should have frozen
    1365                 :            :  * data present for that commit).  In that case, we don't relink the
    1366                 :            :  * buffer: that only gets done when the old transaction finally
    1367                 :            :  * completes its commit.
    1368                 :            :  */
    1369                 :          3 : int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
    1370                 :            : {
    1371                 :          3 :         transaction_t *transaction = handle->h_transaction;
    1372                 :            :         journal_t *journal;
    1373                 :            :         struct journal_head *jh;
    1374                 :            :         int ret = 0;
    1375                 :            : 
    1376                 :          3 :         if (is_handle_aborted(handle))
    1377                 :            :                 return -EROFS;
    1378                 :          3 :         if (!buffer_jbd(bh))
    1379                 :            :                 return -EUCLEAN;
    1380                 :            : 
    1381                 :            :         /*
    1382                 :            :          * We don't grab jh reference here since the buffer must be part
    1383                 :            :          * of the running transaction.
    1384                 :            :          */
    1385                 :            :         jh = bh2jh(bh);
    1386                 :            :         jbd_debug(5, "journal_head %p\n", jh);
    1387                 :            :         JBUFFER_TRACE(jh, "entry");
    1388                 :            : 
    1389                 :            :         /*
    1390                 :            :          * This and the following assertions are unreliable since we may see jh
    1391                 :            :          * in inconsistent state unless we grab bh_state lock. But this is
    1392                 :            :          * crucial to catch bugs so let's do a reliable check until the
    1393                 :            :          * lockless handling is fully proven.
    1394                 :            :          */
    1395                 :          3 :         if (jh->b_transaction != transaction &&
    1396                 :          3 :             jh->b_next_transaction != transaction) {
    1397                 :            :                 jbd_lock_bh_state(bh);
    1398                 :          1 :                 J_ASSERT_JH(jh, jh->b_transaction == transaction ||
    1399                 :            :                                 jh->b_next_transaction == transaction);
    1400                 :            :                 jbd_unlock_bh_state(bh);
    1401                 :            :         }
    1402                 :          3 :         if (jh->b_modified == 1) {
    1403                 :            :                 /* If it's in our transaction it must be in BJ_Metadata list. */
    1404                 :          3 :                 if (jh->b_transaction == transaction &&
    1405                 :          3 :                     jh->b_jlist != BJ_Metadata) {
    1406                 :            :                         jbd_lock_bh_state(bh);
    1407                 :          1 :                         if (jh->b_transaction == transaction &&
    1408                 :          1 :                             jh->b_jlist != BJ_Metadata)
    1409                 :          0 :                                 pr_err("JBD2: assertion failure: h_type=%u "
    1410                 :            :                                        "h_line_no=%u block_no=%llu jlist=%u\n",
    1411                 :            :                                        handle->h_type, handle->h_line_no,
    1412                 :            :                                        (unsigned long long) bh->b_blocknr,
    1413                 :            :                                        jh->b_jlist);
    1414                 :          1 :                         J_ASSERT_JH(jh, jh->b_transaction != transaction ||
    1415                 :            :                                         jh->b_jlist == BJ_Metadata);
    1416                 :            :                         jbd_unlock_bh_state(bh);
    1417                 :            :                 }
    1418                 :            :                 goto out;
    1419                 :            :         }
    1420                 :            : 
    1421                 :          3 :         journal = transaction->t_journal;
    1422                 :            :         jbd_lock_bh_state(bh);
    1423                 :            : 
    1424                 :          3 :         if (jh->b_modified == 0) {
    1425                 :            :                 /*
    1426                 :            :                  * This buffer's got modified and becoming part
    1427                 :            :                  * of the transaction. This needs to be done
    1428                 :            :                  * once a transaction -bzzz
    1429                 :            :                  */
    1430                 :          3 :                 if (handle->h_buffer_credits <= 0) {
    1431                 :            :                         ret = -ENOSPC;
    1432                 :            :                         goto out_unlock_bh;
    1433                 :            :                 }
    1434                 :          3 :                 jh->b_modified = 1;
    1435                 :          3 :                 handle->h_buffer_credits--;
    1436                 :            :         }
    1437                 :            : 
    1438                 :            :         /*
    1439                 :            :          * fastpath, to avoid expensive locking.  If this buffer is already
    1440                 :            :          * on the running transaction's metadata list there is nothing to do.
    1441                 :            :          * Nobody can take it off again because there is a handle open.
    1442                 :            :          * I _think_ we're OK here with SMP barriers - a mistaken decision will
    1443                 :            :          * result in this test being false, so we go in and take the locks.
    1444                 :            :          */
    1445                 :          3 :         if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
    1446                 :            :                 JBUFFER_TRACE(jh, "fastpath");
    1447                 :          0 :                 if (unlikely(jh->b_transaction !=
    1448                 :            :                              journal->j_running_transaction)) {
    1449                 :          0 :                         printk(KERN_ERR "JBD2: %s: "
    1450                 :            :                                "jh->b_transaction (%llu, %p, %u) != "
    1451                 :            :                                "journal->j_running_transaction (%p, %u)\n",
    1452                 :          0 :                                journal->j_devname,
    1453                 :            :                                (unsigned long long) bh->b_blocknr,
    1454                 :            :                                jh->b_transaction,
    1455                 :            :                                jh->b_transaction ? jh->b_transaction->t_tid : 0,
    1456                 :            :                                journal->j_running_transaction,
    1457                 :            :                                journal->j_running_transaction ?
    1458                 :            :                                journal->j_running_transaction->t_tid : 0);
    1459                 :            :                         ret = -EINVAL;
    1460                 :            :                 }
    1461                 :            :                 goto out_unlock_bh;
    1462                 :            :         }
    1463                 :            : 
    1464                 :            :         set_buffer_jbddirty(bh);
    1465                 :            : 
    1466                 :            :         /*
    1467                 :            :          * Metadata already on the current transaction list doesn't
    1468                 :            :          * need to be filed.  Metadata on another transaction's list must
    1469                 :            :          * be committing, and will be refiled once the commit completes:
    1470                 :            :          * leave it alone for now.
    1471                 :            :          */
    1472                 :          3 :         if (jh->b_transaction != transaction) {
    1473                 :            :                 JBUFFER_TRACE(jh, "already on other transaction");
    1474                 :          3 :                 if (unlikely(((jh->b_transaction !=
    1475                 :            :                                journal->j_committing_transaction)) ||
    1476                 :            :                              (jh->b_next_transaction != transaction))) {
    1477                 :          0 :                         printk(KERN_ERR "jbd2_journal_dirty_metadata: %s: "
    1478                 :            :                                "bad jh for block %llu: "
    1479                 :            :                                "transaction (%p, %u), "
    1480                 :            :                                "jh->b_transaction (%p, %u), "
    1481                 :            :                                "jh->b_next_transaction (%p, %u), jlist %u\n",
    1482                 :          0 :                                journal->j_devname,
    1483                 :            :                                (unsigned long long) bh->b_blocknr,
    1484                 :            :                                transaction, transaction->t_tid,
    1485                 :            :                                jh->b_transaction,
    1486                 :            :                                jh->b_transaction ?
    1487                 :            :                                jh->b_transaction->t_tid : 0,
    1488                 :            :                                jh->b_next_transaction,
    1489                 :          0 :                                jh->b_next_transaction ?
    1490                 :            :                                jh->b_next_transaction->t_tid : 0,
    1491                 :            :                                jh->b_jlist);
    1492                 :          0 :                         WARN_ON(1);
    1493                 :            :                         ret = -EINVAL;
    1494                 :            :                 }
    1495                 :            :                 /* And this case is illegal: we can't reuse another
    1496                 :            :                  * transaction's data buffer, ever. */
    1497                 :            :                 goto out_unlock_bh;
    1498                 :            :         }
    1499                 :            : 
    1500                 :            :         /* That test should have eliminated the following case: */
    1501                 :          3 :         J_ASSERT_JH(jh, jh->b_frozen_data == NULL);
    1502                 :            : 
    1503                 :            :         JBUFFER_TRACE(jh, "file as BJ_Metadata");
    1504                 :            :         spin_lock(&journal->j_list_lock);
    1505                 :          3 :         __jbd2_journal_file_buffer(jh, transaction, BJ_Metadata);
    1506                 :            :         spin_unlock(&journal->j_list_lock);
    1507                 :            : out_unlock_bh:
    1508                 :            :         jbd_unlock_bh_state(bh);
    1509                 :            : out:
    1510                 :            :         JBUFFER_TRACE(jh, "exit");
    1511                 :          3 :         return ret;
    1512                 :            : }
    1513                 :            : 
    1514                 :            : /**
    1515                 :            :  * void jbd2_journal_forget() - bforget() for potentially-journaled buffers.
    1516                 :            :  * @handle: transaction handle
    1517                 :            :  * @bh:     bh to 'forget'
    1518                 :            :  *
    1519                 :            :  * We can only do the bforget if there are no commits pending against the
    1520                 :            :  * buffer.  If the buffer is dirty in the current running transaction we
    1521                 :            :  * can safely unlink it.
    1522                 :            :  *
    1523                 :            :  * bh may not be a journalled buffer at all - it may be a non-JBD
    1524                 :            :  * buffer which came off the hashtable.  Check for this.
    1525                 :            :  *
    1526                 :            :  * Decrements bh->b_count by one.
    1527                 :            :  *
    1528                 :            :  * Allow this call even if the handle has aborted --- it may be part of
    1529                 :            :  * the caller's cleanup after an abort.
    1530                 :            :  */
    1531                 :          3 : int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh)
    1532                 :            : {
    1533                 :          3 :         transaction_t *transaction = handle->h_transaction;
    1534                 :            :         journal_t *journal;
    1535                 :            :         struct journal_head *jh;
    1536                 :            :         int drop_reserve = 0;
    1537                 :            :         int err = 0;
    1538                 :            :         int was_modified = 0;
    1539                 :            : 
    1540                 :          3 :         if (is_handle_aborted(handle))
    1541                 :            :                 return -EROFS;
    1542                 :          3 :         journal = transaction->t_journal;
    1543                 :            : 
    1544                 :            :         BUFFER_TRACE(bh, "entry");
    1545                 :            : 
    1546                 :            :         jbd_lock_bh_state(bh);
    1547                 :            : 
    1548                 :          3 :         if (!buffer_jbd(bh))
    1549                 :            :                 goto not_jbd;
    1550                 :            :         jh = bh2jh(bh);
    1551                 :            : 
    1552                 :            :         /* Critical error: attempting to delete a bitmap buffer, maybe?
    1553                 :            :          * Don't do any jbd operations, and return an error. */
    1554                 :          3 :         if (!J_EXPECT_JH(jh, !jh->b_committed_data,
    1555                 :            :                          "inconsistent data on disk")) {
    1556                 :            :                 err = -EIO;
    1557                 :            :                 goto not_jbd;
    1558                 :            :         }
    1559                 :            : 
    1560                 :            :         /* keep track of whether or not this transaction modified us */
    1561                 :          3 :         was_modified = jh->b_modified;
    1562                 :            : 
    1563                 :            :         /*
    1564                 :            :          * The buffer's going from the transaction, we must drop
    1565                 :            :          * all references -bzzz
    1566                 :            :          */
    1567                 :          3 :         jh->b_modified = 0;
    1568                 :            : 
    1569                 :          3 :         if (jh->b_transaction == transaction) {
    1570                 :          3 :                 J_ASSERT_JH(jh, !jh->b_frozen_data);
    1571                 :            : 
    1572                 :            :                 /* If we are forgetting a buffer which is already part
    1573                 :            :                  * of this transaction, then we can just drop it from
    1574                 :            :                  * the transaction immediately. */
    1575                 :            :                 clear_buffer_dirty(bh);
    1576                 :            :                 clear_buffer_jbddirty(bh);
    1577                 :            : 
    1578                 :            :                 JBUFFER_TRACE(jh, "belongs to current transaction: unfile");
    1579                 :            : 
    1580                 :            :                 /*
    1581                 :            :                  * we only want to drop a reference if this transaction
    1582                 :            :                  * modified the buffer
    1583                 :            :                  */
    1584                 :          3 :                 if (was_modified)
    1585                 :            :                         drop_reserve = 1;
    1586                 :            : 
    1587                 :            :                 /*
    1588                 :            :                  * We are no longer going to journal this buffer.
    1589                 :            :                  * However, the commit of this transaction is still
    1590                 :            :                  * important to the buffer: the delete that we are now
    1591                 :            :                  * processing might obsolete an old log entry, so by
    1592                 :            :                  * committing, we can satisfy the buffer's checkpoint.
    1593                 :            :                  *
    1594                 :            :                  * So, if we have a checkpoint on the buffer, we should
    1595                 :            :                  * now refile the buffer on our BJ_Forget list so that
    1596                 :            :                  * we know to remove the checkpoint after we commit.
    1597                 :            :                  */
    1598                 :            : 
    1599                 :            :                 spin_lock(&journal->j_list_lock);
    1600                 :          3 :                 if (jh->b_cp_transaction) {
    1601                 :          3 :                         __jbd2_journal_temp_unlink_buffer(jh);
    1602                 :          3 :                         __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
    1603                 :            :                 } else {
    1604                 :            :                         __jbd2_journal_unfile_buffer(jh);
    1605                 :          3 :                         if (!buffer_jbd(bh)) {
    1606                 :            :                                 spin_unlock(&journal->j_list_lock);
    1607                 :            :                                 goto not_jbd;
    1608                 :            :                         }
    1609                 :            :                 }
    1610                 :            :                 spin_unlock(&journal->j_list_lock);
    1611                 :          3 :         } else if (jh->b_transaction) {
    1612                 :          0 :                 J_ASSERT_JH(jh, (jh->b_transaction ==
    1613                 :            :                                  journal->j_committing_transaction));
    1614                 :            :                 /* However, if the buffer is still owned by a prior
    1615                 :            :                  * (committing) transaction, we can't drop it yet... */
    1616                 :            :                 JBUFFER_TRACE(jh, "belongs to older transaction");
    1617                 :            :                 /* ... but we CAN drop it from the new transaction through
    1618                 :            :                  * marking the buffer as freed and set j_next_transaction to
    1619                 :            :                  * the new transaction, so that not only the commit code
    1620                 :            :                  * knows it should clear dirty bits when it is done with the
    1621                 :            :                  * buffer, but also the buffer can be checkpointed only
    1622                 :            :                  * after the new transaction commits. */
    1623                 :            : 
    1624                 :            :                 set_buffer_freed(bh);
    1625                 :            : 
    1626                 :          0 :                 if (!jh->b_next_transaction) {
    1627                 :            :                         spin_lock(&journal->j_list_lock);
    1628                 :          0 :                         jh->b_next_transaction = transaction;
    1629                 :            :                         spin_unlock(&journal->j_list_lock);
    1630                 :            :                 } else {
    1631                 :          0 :                         J_ASSERT(jh->b_next_transaction == transaction);
    1632                 :            : 
    1633                 :            :                         /*
    1634                 :            :                          * only drop a reference if this transaction modified
    1635                 :            :                          * the buffer
    1636                 :            :                          */
    1637                 :          0 :                         if (was_modified)
    1638                 :            :                                 drop_reserve = 1;
    1639                 :            :                 }
    1640                 :            :         } else {
    1641                 :            :                 /*
    1642                 :            :                  * Finally, if the buffer is not belongs to any
    1643                 :            :                  * transaction, we can just drop it now if it has no
    1644                 :            :                  * checkpoint.
    1645                 :            :                  */
    1646                 :            :                 spin_lock(&journal->j_list_lock);
    1647                 :          3 :                 if (!jh->b_cp_transaction) {
    1648                 :            :                         JBUFFER_TRACE(jh, "belongs to none transaction");
    1649                 :            :                         spin_unlock(&journal->j_list_lock);
    1650                 :            :                         goto not_jbd;
    1651                 :            :                 }
    1652                 :            : 
    1653                 :            :                 /*
    1654                 :            :                  * Otherwise, if the buffer has been written to disk,
    1655                 :            :                  * it is safe to remove the checkpoint and drop it.
    1656                 :            :                  */
    1657                 :          3 :                 if (!buffer_dirty(bh)) {
    1658                 :          0 :                         __jbd2_journal_remove_checkpoint(jh);
    1659                 :            :                         spin_unlock(&journal->j_list_lock);
    1660                 :            :                         goto not_jbd;
    1661                 :            :                 }
    1662                 :            : 
    1663                 :            :                 /*
    1664                 :            :                  * The buffer is still not written to disk, we should
    1665                 :            :                  * attach this buffer to current transaction so that the
    1666                 :            :                  * buffer can be checkpointed only after the current
    1667                 :            :                  * transaction commits.
    1668                 :            :                  */
    1669                 :            :                 clear_buffer_dirty(bh);
    1670                 :          3 :                 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
    1671                 :            :                 spin_unlock(&journal->j_list_lock);
    1672                 :            :         }
    1673                 :            : 
    1674                 :            :         jbd_unlock_bh_state(bh);
    1675                 :          3 :         __brelse(bh);
    1676                 :            : drop:
    1677                 :          3 :         if (drop_reserve) {
    1678                 :            :                 /* no need to reserve log space for this block -bzzz */
    1679                 :          3 :                 handle->h_buffer_credits++;
    1680                 :            :         }
    1681                 :          3 :         return err;
    1682                 :            : 
    1683                 :            : not_jbd:
    1684                 :            :         jbd_unlock_bh_state(bh);
    1685                 :          3 :         __bforget(bh);
    1686                 :          3 :         goto drop;
    1687                 :            : }
    1688                 :            : 
    1689                 :            : /**
    1690                 :            :  * int jbd2_journal_stop() - complete a transaction
    1691                 :            :  * @handle: transaction to complete.
    1692                 :            :  *
    1693                 :            :  * All done for a particular handle.
    1694                 :            :  *
    1695                 :            :  * There is not much action needed here.  We just return any remaining
    1696                 :            :  * buffer credits to the transaction and remove the handle.  The only
    1697                 :            :  * complication is that we need to start a commit operation if the
    1698                 :            :  * filesystem is marked for synchronous update.
    1699                 :            :  *
    1700                 :            :  * jbd2_journal_stop itself will not usually return an error, but it may
    1701                 :            :  * do so in unusual circumstances.  In particular, expect it to
    1702                 :            :  * return -EIO if a jbd2_journal_abort has been executed since the
    1703                 :            :  * transaction began.
    1704                 :            :  */
    1705                 :          3 : int jbd2_journal_stop(handle_t *handle)
    1706                 :            : {
    1707                 :          3 :         transaction_t *transaction = handle->h_transaction;
    1708                 :            :         journal_t *journal;
    1709                 :            :         int err = 0, wait_for_commit = 0;
    1710                 :            :         tid_t tid;
    1711                 :            :         pid_t pid;
    1712                 :            : 
    1713                 :          3 :         if (!transaction) {
    1714                 :            :                 /*
    1715                 :            :                  * Handle is already detached from the transaction so
    1716                 :            :                  * there is nothing to do other than decrease a refcount,
    1717                 :            :                  * or free the handle if refcount drops to zero
    1718                 :            :                  */
    1719                 :          0 :                 if (--handle->h_ref > 0) {
    1720                 :            :                         jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
    1721                 :            :                                                          handle->h_ref);
    1722                 :            :                         return err;
    1723                 :            :                 } else {
    1724                 :          0 :                         if (handle->h_rsv_handle)
    1725                 :            :                                 jbd2_free_handle(handle->h_rsv_handle);
    1726                 :            :                         goto free_and_exit;
    1727                 :            :                 }
    1728                 :            :         }
    1729                 :          3 :         journal = transaction->t_journal;
    1730                 :            : 
    1731                 :          3 :         J_ASSERT(journal_current_handle() == handle);
    1732                 :            : 
    1733                 :          3 :         if (is_handle_aborted(handle))
    1734                 :            :                 err = -EIO;
    1735                 :            :         else
    1736                 :          3 :                 J_ASSERT(atomic_read(&transaction->t_updates) > 0);
    1737                 :            : 
    1738                 :          3 :         if (--handle->h_ref > 0) {
    1739                 :            :                 jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
    1740                 :            :                           handle->h_ref);
    1741                 :            :                 return err;
    1742                 :            :         }
    1743                 :            : 
    1744                 :            :         jbd_debug(4, "Handle %p going down\n", handle);
    1745                 :          3 :         trace_jbd2_handle_stats(journal->j_fs_dev->bd_dev,
    1746                 :          3 :                                 transaction->t_tid,
    1747                 :          3 :                                 handle->h_type, handle->h_line_no,
    1748                 :          3 :                                 jiffies - handle->h_start_jiffies,
    1749                 :          3 :                                 handle->h_sync, handle->h_requested_credits,
    1750                 :          3 :                                 (handle->h_requested_credits -
    1751                 :          3 :                                  handle->h_buffer_credits));
    1752                 :            : 
    1753                 :            :         /*
    1754                 :            :          * Implement synchronous transaction batching.  If the handle
    1755                 :            :          * was synchronous, don't force a commit immediately.  Let's
    1756                 :            :          * yield and let another thread piggyback onto this
    1757                 :            :          * transaction.  Keep doing that while new threads continue to
    1758                 :            :          * arrive.  It doesn't cost much - we're about to run a commit
    1759                 :            :          * and sleep on IO anyway.  Speeds up many-threaded, many-dir
    1760                 :            :          * operations by 30x or more...
    1761                 :            :          *
    1762                 :            :          * We try and optimize the sleep time against what the
    1763                 :            :          * underlying disk can do, instead of having a static sleep
    1764                 :            :          * time.  This is useful for the case where our storage is so
    1765                 :            :          * fast that it is more optimal to go ahead and force a flush
    1766                 :            :          * and wait for the transaction to be committed than it is to
    1767                 :            :          * wait for an arbitrary amount of time for new writers to
    1768                 :            :          * join the transaction.  We achieve this by measuring how
    1769                 :            :          * long it takes to commit a transaction, and compare it with
    1770                 :            :          * how long this transaction has been running, and if run time
    1771                 :            :          * < commit time then we sleep for the delta and commit.  This
    1772                 :            :          * greatly helps super fast disks that would see slowdowns as
    1773                 :            :          * more threads started doing fsyncs.
    1774                 :            :          *
    1775                 :            :          * But don't do this if this process was the most recent one
    1776                 :            :          * to perform a synchronous write.  We do this to detect the
    1777                 :            :          * case where a single process is doing a stream of sync
    1778                 :            :          * writes.  No point in waiting for joiners in that case.
    1779                 :            :          *
    1780                 :            :          * Setting max_batch_time to 0 disables this completely.
    1781                 :            :          */
    1782                 :          3 :         pid = current->pid;
    1783                 :          3 :         if (handle->h_sync && journal->j_last_sync_writer != pid &&
    1784                 :          0 :             journal->j_max_batch_time) {
    1785                 :            :                 u64 commit_time, trans_time;
    1786                 :            : 
    1787                 :          0 :                 journal->j_last_sync_writer = pid;
    1788                 :            : 
    1789                 :          0 :                 read_lock(&journal->j_state_lock);
    1790                 :          0 :                 commit_time = journal->j_average_commit_time;
    1791                 :            :                 read_unlock(&journal->j_state_lock);
    1792                 :            : 
    1793                 :          0 :                 trans_time = ktime_to_ns(ktime_sub(ktime_get(),
    1794                 :            :                                                    transaction->t_start_time));
    1795                 :            : 
    1796                 :          0 :                 commit_time = max_t(u64, commit_time,
    1797                 :            :                                     1000*journal->j_min_batch_time);
    1798                 :          0 :                 commit_time = min_t(u64, commit_time,
    1799                 :            :                                     1000*journal->j_max_batch_time);
    1800                 :            : 
    1801                 :          0 :                 if (trans_time < commit_time) {
    1802                 :          0 :                         ktime_t expires = ktime_add_ns(ktime_get(),
    1803                 :            :                                                        commit_time);
    1804                 :          0 :                         set_current_state(TASK_UNINTERRUPTIBLE);
    1805                 :          0 :                         schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
    1806                 :            :                 }
    1807                 :            :         }
    1808                 :            : 
    1809                 :          3 :         if (handle->h_sync)
    1810                 :          0 :                 transaction->t_synchronous_commit = 1;
    1811                 :          3 :         current->journal_info = NULL;
    1812                 :          3 :         atomic_sub(handle->h_buffer_credits,
    1813                 :            :                    &transaction->t_outstanding_credits);
    1814                 :            : 
    1815                 :            :         /*
    1816                 :            :          * If the handle is marked SYNC, we need to set another commit
    1817                 :            :          * going!  We also want to force a commit if the current
    1818                 :            :          * transaction is occupying too much of the log, or if the
    1819                 :            :          * transaction is too old now.
    1820                 :            :          */
    1821                 :          3 :         if (handle->h_sync ||
    1822                 :          3 :             (atomic_read(&transaction->t_outstanding_credits) >
    1823                 :          3 :              journal->j_max_transaction_buffers) ||
    1824                 :          3 :             time_after_eq(jiffies, transaction->t_expires)) {
    1825                 :            :                 /* Do this even for aborted journals: an abort still
    1826                 :            :                  * completes the commit thread, it just doesn't write
    1827                 :            :                  * anything to disk. */
    1828                 :            : 
    1829                 :            :                 jbd_debug(2, "transaction too old, requesting commit for "
    1830                 :            :                                         "handle %p\n", handle);
    1831                 :            :                 /* This is non-blocking */
    1832                 :          3 :                 jbd2_log_start_commit(journal, transaction->t_tid);
    1833                 :            : 
    1834                 :            :                 /*
    1835                 :            :                  * Special case: JBD2_SYNC synchronous updates require us
    1836                 :            :                  * to wait for the commit to complete.
    1837                 :            :                  */
    1838                 :          3 :                 if (handle->h_sync && !(current->flags & PF_MEMALLOC))
    1839                 :            :                         wait_for_commit = 1;
    1840                 :            :         }
    1841                 :            : 
    1842                 :            :         /*
    1843                 :            :          * Once we drop t_updates, if it goes to zero the transaction
    1844                 :            :          * could start committing on us and eventually disappear.  So
    1845                 :            :          * once we do this, we must not dereference transaction
    1846                 :            :          * pointer again.
    1847                 :            :          */
    1848                 :          3 :         tid = transaction->t_tid;
    1849                 :          3 :         if (atomic_dec_and_test(&transaction->t_updates)) {
    1850                 :          3 :                 wake_up(&journal->j_wait_updates);
    1851                 :          3 :                 if (journal->j_barrier_count)
    1852                 :          0 :                         wake_up(&journal->j_wait_transaction_locked);
    1853                 :            :         }
    1854                 :            : 
    1855                 :            :         rwsem_release(&journal->j_trans_commit_map, 1, _THIS_IP_);
    1856                 :            : 
    1857                 :          3 :         if (wait_for_commit)
    1858                 :          0 :                 err = jbd2_log_wait_commit(journal, tid);
    1859                 :            : 
    1860                 :          3 :         if (handle->h_rsv_handle)
    1861                 :          0 :                 jbd2_journal_free_reserved(handle->h_rsv_handle);
    1862                 :            : free_and_exit:
    1863                 :            :         /*
    1864                 :            :          * Scope of the GFP_NOFS context is over here and so we can restore the
    1865                 :            :          * original alloc context.
    1866                 :            :          */
    1867                 :          3 :         memalloc_nofs_restore(handle->saved_alloc_context);
    1868                 :            :         jbd2_free_handle(handle);
    1869                 :          3 :         return err;
    1870                 :            : }
    1871                 :            : 
    1872                 :            : /*
    1873                 :            :  *
    1874                 :            :  * List management code snippets: various functions for manipulating the
    1875                 :            :  * transaction buffer lists.
    1876                 :            :  *
    1877                 :            :  */
    1878                 :            : 
    1879                 :            : /*
    1880                 :            :  * Append a buffer to a transaction list, given the transaction's list head
    1881                 :            :  * pointer.
    1882                 :            :  *
    1883                 :            :  * j_list_lock is held.
    1884                 :            :  *
    1885                 :            :  * jbd_lock_bh_state(jh2bh(jh)) is held.
    1886                 :            :  */
    1887                 :            : 
    1888                 :            : static inline void
    1889                 :            : __blist_add_buffer(struct journal_head **list, struct journal_head *jh)
    1890                 :            : {
    1891                 :          3 :         if (!*list) {
    1892                 :          3 :                 jh->b_tnext = jh->b_tprev = jh;
    1893                 :          3 :                 *list = jh;
    1894                 :            :         } else {
    1895                 :            :                 /* Insert at the tail of the list to preserve order */
    1896                 :          3 :                 struct journal_head *first = *list, *last = first->b_tprev;
    1897                 :          3 :                 jh->b_tprev = last;
    1898                 :          3 :                 jh->b_tnext = first;
    1899                 :          3 :                 last->b_tnext = first->b_tprev = jh;
    1900                 :            :         }
    1901                 :            : }
    1902                 :            : 
    1903                 :            : /*
    1904                 :            :  * Remove a buffer from a transaction list, given the transaction's list
    1905                 :            :  * head pointer.
    1906                 :            :  *
    1907                 :            :  * Called with j_list_lock held, and the journal may not be locked.
    1908                 :            :  *
    1909                 :            :  * jbd_lock_bh_state(jh2bh(jh)) is held.
    1910                 :            :  */
    1911                 :            : 
    1912                 :            : static inline void
    1913                 :            : __blist_del_buffer(struct journal_head **list, struct journal_head *jh)
    1914                 :            : {
    1915                 :          3 :         if (*list == jh) {
    1916                 :          3 :                 *list = jh->b_tnext;
    1917                 :          3 :                 if (*list == jh)
    1918                 :          3 :                         *list = NULL;
    1919                 :            :         }
    1920                 :          3 :         jh->b_tprev->b_tnext = jh->b_tnext;
    1921                 :          3 :         jh->b_tnext->b_tprev = jh->b_tprev;
    1922                 :            : }
    1923                 :            : 
    1924                 :            : /*
    1925                 :            :  * Remove a buffer from the appropriate transaction list.
    1926                 :            :  *
    1927                 :            :  * Note that this function can *change* the value of
    1928                 :            :  * bh->b_transaction->t_buffers, t_forget, t_shadow_list, t_log_list or
    1929                 :            :  * t_reserved_list.  If the caller is holding onto a copy of one of these
    1930                 :            :  * pointers, it could go bad.  Generally the caller needs to re-read the
    1931                 :            :  * pointer from the transaction_t.
    1932                 :            :  *
    1933                 :            :  * Called under j_list_lock.
    1934                 :            :  */
    1935                 :          3 : static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
    1936                 :            : {
    1937                 :            :         struct journal_head **list = NULL;
    1938                 :            :         transaction_t *transaction;
    1939                 :            :         struct buffer_head *bh = jh2bh(jh);
    1940                 :            : 
    1941                 :          3 :         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
    1942                 :          3 :         transaction = jh->b_transaction;
    1943                 :          3 :         if (transaction)
    1944                 :          3 :                 assert_spin_locked(&transaction->t_journal->j_list_lock);
    1945                 :            : 
    1946                 :          3 :         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
    1947                 :          3 :         if (jh->b_jlist != BJ_None)
    1948                 :          3 :                 J_ASSERT_JH(jh, transaction != NULL);
    1949                 :            : 
    1950                 :          3 :         switch (jh->b_jlist) {
    1951                 :            :         case BJ_None:
    1952                 :          3 :                 return;
    1953                 :            :         case BJ_Metadata:
    1954                 :          3 :                 transaction->t_nr_buffers--;
    1955                 :          3 :                 J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
    1956                 :          3 :                 list = &transaction->t_buffers;
    1957                 :          3 :                 break;
    1958                 :            :         case BJ_Forget:
    1959                 :          3 :                 list = &transaction->t_forget;
    1960                 :          3 :                 break;
    1961                 :            :         case BJ_Shadow:
    1962                 :          3 :                 list = &transaction->t_shadow_list;
    1963                 :          3 :                 break;
    1964                 :            :         case BJ_Reserved:
    1965                 :          3 :                 list = &transaction->t_reserved_list;
    1966                 :          3 :                 break;
    1967                 :            :         }
    1968                 :            : 
    1969                 :            :         __blist_del_buffer(list, jh);
    1970                 :          3 :         jh->b_jlist = BJ_None;
    1971                 :          3 :         if (transaction && is_journal_aborted(transaction->t_journal))
    1972                 :            :                 clear_buffer_jbddirty(bh);
    1973                 :          3 :         else if (test_clear_buffer_jbddirty(bh))
    1974                 :          3 :                 mark_buffer_dirty(bh);  /* Expose it to the VM */
    1975                 :            : }
    1976                 :            : 
    1977                 :            : /*
    1978                 :            :  * Remove buffer from all transactions.
    1979                 :            :  *
    1980                 :            :  * Called with bh_state lock and j_list_lock
    1981                 :            :  *
    1982                 :            :  * jh and bh may be already freed when this function returns.
    1983                 :            :  */
    1984                 :            : static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
    1985                 :            : {
    1986                 :          3 :         __jbd2_journal_temp_unlink_buffer(jh);
    1987                 :          3 :         jh->b_transaction = NULL;
    1988                 :          3 :         jbd2_journal_put_journal_head(jh);
    1989                 :            : }
    1990                 :            : 
    1991                 :          0 : void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
    1992                 :            : {
    1993                 :            :         struct buffer_head *bh = jh2bh(jh);
    1994                 :            : 
    1995                 :            :         /* Get reference so that buffer cannot be freed before we unlock it */
    1996                 :            :         get_bh(bh);
    1997                 :            :         jbd_lock_bh_state(bh);
    1998                 :            :         spin_lock(&journal->j_list_lock);
    1999                 :            :         __jbd2_journal_unfile_buffer(jh);
    2000                 :            :         spin_unlock(&journal->j_list_lock);
    2001                 :            :         jbd_unlock_bh_state(bh);
    2002                 :          0 :         __brelse(bh);
    2003                 :          0 : }
    2004                 :            : 
    2005                 :            : /*
    2006                 :            :  * Called from jbd2_journal_try_to_free_buffers().
    2007                 :            :  *
    2008                 :            :  * Called under jbd_lock_bh_state(bh)
    2009                 :            :  */
    2010                 :            : static void
    2011                 :          0 : __journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
    2012                 :            : {
    2013                 :            :         struct journal_head *jh;
    2014                 :            : 
    2015                 :            :         jh = bh2jh(bh);
    2016                 :            : 
    2017                 :          0 :         if (buffer_locked(bh) || buffer_dirty(bh))
    2018                 :            :                 goto out;
    2019                 :            : 
    2020                 :          0 :         if (jh->b_next_transaction != NULL || jh->b_transaction != NULL)
    2021                 :            :                 goto out;
    2022                 :            : 
    2023                 :            :         spin_lock(&journal->j_list_lock);
    2024                 :          0 :         if (jh->b_cp_transaction != NULL) {
    2025                 :            :                 /* written-back checkpointed metadata buffer */
    2026                 :            :                 JBUFFER_TRACE(jh, "remove from checkpoint list");
    2027                 :          0 :                 __jbd2_journal_remove_checkpoint(jh);
    2028                 :            :         }
    2029                 :            :         spin_unlock(&journal->j_list_lock);
    2030                 :            : out:
    2031                 :          0 :         return;
    2032                 :            : }
    2033                 :            : 
    2034                 :            : /**
    2035                 :            :  * int jbd2_journal_try_to_free_buffers() - try to free page buffers.
    2036                 :            :  * @journal: journal for operation
    2037                 :            :  * @page: to try and free
    2038                 :            :  * @gfp_mask: we use the mask to detect how hard should we try to release
    2039                 :            :  * buffers. If __GFP_DIRECT_RECLAIM and __GFP_FS is set, we wait for commit
    2040                 :            :  * code to release the buffers.
    2041                 :            :  *
    2042                 :            :  *
    2043                 :            :  * For all the buffers on this page,
    2044                 :            :  * if they are fully written out ordered data, move them onto BUF_CLEAN
    2045                 :            :  * so try_to_free_buffers() can reap them.
    2046                 :            :  *
    2047                 :            :  * This function returns non-zero if we wish try_to_free_buffers()
    2048                 :            :  * to be called. We do this if the page is releasable by try_to_free_buffers().
    2049                 :            :  * We also do it if the page has locked or dirty buffers and the caller wants
    2050                 :            :  * us to perform sync or async writeout.
    2051                 :            :  *
    2052                 :            :  * This complicates JBD locking somewhat.  We aren't protected by the
    2053                 :            :  * BKL here.  We wish to remove the buffer from its committing or
    2054                 :            :  * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
    2055                 :            :  *
    2056                 :            :  * This may *change* the value of transaction_t->t_datalist, so anyone
    2057                 :            :  * who looks at t_datalist needs to lock against this function.
    2058                 :            :  *
    2059                 :            :  * Even worse, someone may be doing a jbd2_journal_dirty_data on this
    2060                 :            :  * buffer.  So we need to lock against that.  jbd2_journal_dirty_data()
    2061                 :            :  * will come out of the lock with the buffer dirty, which makes it
    2062                 :            :  * ineligible for release here.
    2063                 :            :  *
    2064                 :            :  * Who else is affected by this?  hmm...  Really the only contender
    2065                 :            :  * is do_get_write_access() - it could be looking at the buffer while
    2066                 :            :  * journal_try_to_free_buffer() is changing its state.  But that
    2067                 :            :  * cannot happen because we never reallocate freed data as metadata
    2068                 :            :  * while the data is part of a transaction.  Yes?
    2069                 :            :  *
    2070                 :            :  * Return 0 on failure, 1 on success
    2071                 :            :  */
    2072                 :          3 : int jbd2_journal_try_to_free_buffers(journal_t *journal,
    2073                 :            :                                 struct page *page, gfp_t gfp_mask)
    2074                 :            : {
    2075                 :            :         struct buffer_head *head;
    2076                 :            :         struct buffer_head *bh;
    2077                 :            :         int ret = 0;
    2078                 :            : 
    2079                 :          3 :         J_ASSERT(PageLocked(page));
    2080                 :            : 
    2081                 :          3 :         head = page_buffers(page);
    2082                 :            :         bh = head;
    2083                 :            :         do {
    2084                 :            :                 struct journal_head *jh;
    2085                 :            : 
    2086                 :            :                 /*
    2087                 :            :                  * We take our own ref against the journal_head here to avoid
    2088                 :            :                  * having to add tons of locking around each instance of
    2089                 :            :                  * jbd2_journal_put_journal_head().
    2090                 :            :                  */
    2091                 :          3 :                 jh = jbd2_journal_grab_journal_head(bh);
    2092                 :          3 :                 if (!jh)
    2093                 :          3 :                         continue;
    2094                 :            : 
    2095                 :            :                 jbd_lock_bh_state(bh);
    2096                 :          0 :                 __journal_try_to_free_buffer(journal, bh);
    2097                 :          0 :                 jbd2_journal_put_journal_head(jh);
    2098                 :            :                 jbd_unlock_bh_state(bh);
    2099                 :          0 :                 if (buffer_jbd(bh))
    2100                 :            :                         goto busy;
    2101                 :          3 :         } while ((bh = bh->b_this_page) != head);
    2102                 :            : 
    2103                 :          3 :         ret = try_to_free_buffers(page);
    2104                 :            : 
    2105                 :            : busy:
    2106                 :          3 :         return ret;
    2107                 :            : }
    2108                 :            : 
    2109                 :            : /*
    2110                 :            :  * This buffer is no longer needed.  If it is on an older transaction's
    2111                 :            :  * checkpoint list we need to record it on this transaction's forget list
    2112                 :            :  * to pin this buffer (and hence its checkpointing transaction) down until
    2113                 :            :  * this transaction commits.  If the buffer isn't on a checkpoint list, we
    2114                 :            :  * release it.
    2115                 :            :  * Returns non-zero if JBD no longer has an interest in the buffer.
    2116                 :            :  *
    2117                 :            :  * Called under j_list_lock.
    2118                 :            :  *
    2119                 :            :  * Called under jbd_lock_bh_state(bh).
    2120                 :            :  */
    2121                 :          0 : static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
    2122                 :            : {
    2123                 :            :         int may_free = 1;
    2124                 :            :         struct buffer_head *bh = jh2bh(jh);
    2125                 :            : 
    2126                 :          0 :         if (jh->b_cp_transaction) {
    2127                 :            :                 JBUFFER_TRACE(jh, "on running+cp transaction");
    2128                 :          0 :                 __jbd2_journal_temp_unlink_buffer(jh);
    2129                 :            :                 /*
    2130                 :            :                  * We don't want to write the buffer anymore, clear the
    2131                 :            :                  * bit so that we don't confuse checks in
    2132                 :            :                  * __journal_file_buffer
    2133                 :            :                  */
    2134                 :            :                 clear_buffer_dirty(bh);
    2135                 :          0 :                 __jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
    2136                 :            :                 may_free = 0;
    2137                 :            :         } else {
    2138                 :            :                 JBUFFER_TRACE(jh, "on running transaction");
    2139                 :            :                 __jbd2_journal_unfile_buffer(jh);
    2140                 :            :         }
    2141                 :          0 :         return may_free;
    2142                 :            : }
    2143                 :            : 
    2144                 :            : /*
    2145                 :            :  * jbd2_journal_invalidatepage
    2146                 :            :  *
    2147                 :            :  * This code is tricky.  It has a number of cases to deal with.
    2148                 :            :  *
    2149                 :            :  * There are two invariants which this code relies on:
    2150                 :            :  *
    2151                 :            :  * i_size must be updated on disk before we start calling invalidatepage on the
    2152                 :            :  * data.
    2153                 :            :  *
    2154                 :            :  *  This is done in ext3 by defining an ext3_setattr method which
    2155                 :            :  *  updates i_size before truncate gets going.  By maintaining this
    2156                 :            :  *  invariant, we can be sure that it is safe to throw away any buffers
    2157                 :            :  *  attached to the current transaction: once the transaction commits,
    2158                 :            :  *  we know that the data will not be needed.
    2159                 :            :  *
    2160                 :            :  *  Note however that we can *not* throw away data belonging to the
    2161                 :            :  *  previous, committing transaction!
    2162                 :            :  *
    2163                 :            :  * Any disk blocks which *are* part of the previous, committing
    2164                 :            :  * transaction (and which therefore cannot be discarded immediately) are
    2165                 :            :  * not going to be reused in the new running transaction
    2166                 :            :  *
    2167                 :            :  *  The bitmap committed_data images guarantee this: any block which is
    2168                 :            :  *  allocated in one transaction and removed in the next will be marked
    2169                 :            :  *  as in-use in the committed_data bitmap, so cannot be reused until
    2170                 :            :  *  the next transaction to delete the block commits.  This means that
    2171                 :            :  *  leaving committing buffers dirty is quite safe: the disk blocks
    2172                 :            :  *  cannot be reallocated to a different file and so buffer aliasing is
    2173                 :            :  *  not possible.
    2174                 :            :  *
    2175                 :            :  *
    2176                 :            :  * The above applies mainly to ordered data mode.  In writeback mode we
    2177                 :            :  * don't make guarantees about the order in which data hits disk --- in
    2178                 :            :  * particular we don't guarantee that new dirty data is flushed before
    2179                 :            :  * transaction commit --- so it is always safe just to discard data
    2180                 :            :  * immediately in that mode.  --sct
    2181                 :            :  */
    2182                 :            : 
    2183                 :            : /*
    2184                 :            :  * The journal_unmap_buffer helper function returns zero if the buffer
    2185                 :            :  * concerned remains pinned as an anonymous buffer belonging to an older
    2186                 :            :  * transaction.
    2187                 :            :  *
    2188                 :            :  * We're outside-transaction here.  Either or both of j_running_transaction
    2189                 :            :  * and j_committing_transaction may be NULL.
    2190                 :            :  */
    2191                 :          0 : static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
    2192                 :            :                                 int partial_page)
    2193                 :            : {
    2194                 :            :         transaction_t *transaction;
    2195                 :            :         struct journal_head *jh;
    2196                 :            :         int may_free = 1;
    2197                 :            : 
    2198                 :            :         BUFFER_TRACE(bh, "entry");
    2199                 :            : 
    2200                 :            :         /*
    2201                 :            :          * It is safe to proceed here without the j_list_lock because the
    2202                 :            :          * buffers cannot be stolen by try_to_free_buffers as long as we are
    2203                 :            :          * holding the page lock. --sct
    2204                 :            :          */
    2205                 :            : 
    2206                 :          0 :         if (!buffer_jbd(bh))
    2207                 :            :                 goto zap_buffer_unlocked;
    2208                 :            : 
    2209                 :            :         /* OK, we have data buffer in journaled mode */
    2210                 :          0 :         write_lock(&journal->j_state_lock);
    2211                 :            :         jbd_lock_bh_state(bh);
    2212                 :            :         spin_lock(&journal->j_list_lock);
    2213                 :            : 
    2214                 :          0 :         jh = jbd2_journal_grab_journal_head(bh);
    2215                 :          0 :         if (!jh)
    2216                 :            :                 goto zap_buffer_no_jh;
    2217                 :            : 
    2218                 :            :         /*
    2219                 :            :          * We cannot remove the buffer from checkpoint lists until the
    2220                 :            :          * transaction adding inode to orphan list (let's call it T)
    2221                 :            :          * is committed.  Otherwise if the transaction changing the
    2222                 :            :          * buffer would be cleaned from the journal before T is
    2223                 :            :          * committed, a crash will cause that the correct contents of
    2224                 :            :          * the buffer will be lost.  On the other hand we have to
    2225                 :            :          * clear the buffer dirty bit at latest at the moment when the
    2226                 :            :          * transaction marking the buffer as freed in the filesystem
    2227                 :            :          * structures is committed because from that moment on the
    2228                 :            :          * block can be reallocated and used by a different page.
    2229                 :            :          * Since the block hasn't been freed yet but the inode has
    2230                 :            :          * already been added to orphan list, it is safe for us to add
    2231                 :            :          * the buffer to BJ_Forget list of the newest transaction.
    2232                 :            :          *
    2233                 :            :          * Also we have to clear buffer_mapped flag of a truncated buffer
    2234                 :            :          * because the buffer_head may be attached to the page straddling
    2235                 :            :          * i_size (can happen only when blocksize < pagesize) and thus the
    2236                 :            :          * buffer_head can be reused when the file is extended again. So we end
    2237                 :            :          * up keeping around invalidated buffers attached to transactions'
    2238                 :            :          * BJ_Forget list just to stop checkpointing code from cleaning up
    2239                 :            :          * the transaction this buffer was modified in.
    2240                 :            :          */
    2241                 :          0 :         transaction = jh->b_transaction;
    2242                 :          0 :         if (transaction == NULL) {
    2243                 :            :                 /* First case: not on any transaction.  If it
    2244                 :            :                  * has no checkpoint link, then we can zap it:
    2245                 :            :                  * it's a writeback-mode buffer so we don't care
    2246                 :            :                  * if it hits disk safely. */
    2247                 :          0 :                 if (!jh->b_cp_transaction) {
    2248                 :            :                         JBUFFER_TRACE(jh, "not on any transaction: zap");
    2249                 :            :                         goto zap_buffer;
    2250                 :            :                 }
    2251                 :            : 
    2252                 :          0 :                 if (!buffer_dirty(bh)) {
    2253                 :            :                         /* bdflush has written it.  We can drop it now */
    2254                 :          0 :                         __jbd2_journal_remove_checkpoint(jh);
    2255                 :          0 :                         goto zap_buffer;
    2256                 :            :                 }
    2257                 :            : 
    2258                 :            :                 /* OK, it must be in the journal but still not
    2259                 :            :                  * written fully to disk: it's metadata or
    2260                 :            :                  * journaled data... */
    2261                 :            : 
    2262                 :          0 :                 if (journal->j_running_transaction) {
    2263                 :            :                         /* ... and once the current transaction has
    2264                 :            :                          * committed, the buffer won't be needed any
    2265                 :            :                          * longer. */
    2266                 :            :                         JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
    2267                 :          0 :                         may_free = __dispose_buffer(jh,
    2268                 :            :                                         journal->j_running_transaction);
    2269                 :          0 :                         goto zap_buffer;
    2270                 :            :                 } else {
    2271                 :            :                         /* There is no currently-running transaction. So the
    2272                 :            :                          * orphan record which we wrote for this file must have
    2273                 :            :                          * passed into commit.  We must attach this buffer to
    2274                 :            :                          * the committing transaction, if it exists. */
    2275                 :          0 :                         if (journal->j_committing_transaction) {
    2276                 :            :                                 JBUFFER_TRACE(jh, "give to committing trans");
    2277                 :          0 :                                 may_free = __dispose_buffer(jh,
    2278                 :            :                                         journal->j_committing_transaction);
    2279                 :          0 :                                 goto zap_buffer;
    2280                 :            :                         } else {
    2281                 :            :                                 /* The orphan record's transaction has
    2282                 :            :                                  * committed.  We can cleanse this buffer */
    2283                 :            :                                 clear_buffer_jbddirty(bh);
    2284                 :          0 :                                 __jbd2_journal_remove_checkpoint(jh);
    2285                 :          0 :                                 goto zap_buffer;
    2286                 :            :                         }
    2287                 :            :                 }
    2288                 :          0 :         } else if (transaction == journal->j_committing_transaction) {
    2289                 :            :                 JBUFFER_TRACE(jh, "on committing transaction");
    2290                 :            :                 /*
    2291                 :            :                  * The buffer is committing, we simply cannot touch
    2292                 :            :                  * it. If the page is straddling i_size we have to wait
    2293                 :            :                  * for commit and try again.
    2294                 :            :                  */
    2295                 :          0 :                 if (partial_page) {
    2296                 :          0 :                         jbd2_journal_put_journal_head(jh);
    2297                 :            :                         spin_unlock(&journal->j_list_lock);
    2298                 :            :                         jbd_unlock_bh_state(bh);
    2299                 :            :                         write_unlock(&journal->j_state_lock);
    2300                 :          0 :                         return -EBUSY;
    2301                 :            :                 }
    2302                 :            :                 /*
    2303                 :            :                  * OK, buffer won't be reachable after truncate. We just clear
    2304                 :            :                  * b_modified to not confuse transaction credit accounting, and
    2305                 :            :                  * set j_next_transaction to the running transaction (if there
    2306                 :            :                  * is one) and mark buffer as freed so that commit code knows
    2307                 :            :                  * it should clear dirty bits when it is done with the buffer.
    2308                 :            :                  */
    2309                 :            :                 set_buffer_freed(bh);
    2310                 :          0 :                 if (journal->j_running_transaction && buffer_jbddirty(bh))
    2311                 :          0 :                         jh->b_next_transaction = journal->j_running_transaction;
    2312                 :          0 :                 jh->b_modified = 0;
    2313                 :          0 :                 jbd2_journal_put_journal_head(jh);
    2314                 :            :                 spin_unlock(&journal->j_list_lock);
    2315                 :            :                 jbd_unlock_bh_state(bh);
    2316                 :            :                 write_unlock(&journal->j_state_lock);
    2317                 :          0 :                 return 0;
    2318                 :            :         } else {
    2319                 :            :                 /* Good, the buffer belongs to the running transaction.
    2320                 :            :                  * We are writing our own transaction's data, not any
    2321                 :            :                  * previous one's, so it is safe to throw it away
    2322                 :            :                  * (remember that we expect the filesystem to have set
    2323                 :            :                  * i_size already for this truncate so recovery will not
    2324                 :            :                  * expose the disk blocks we are discarding here.) */
    2325                 :          0 :                 J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
    2326                 :            :                 JBUFFER_TRACE(jh, "on running transaction");
    2327                 :          0 :                 may_free = __dispose_buffer(jh, transaction);
    2328                 :            :         }
    2329                 :            : 
    2330                 :            : zap_buffer:
    2331                 :            :         /*
    2332                 :            :          * This is tricky. Although the buffer is truncated, it may be reused
    2333                 :            :          * if blocksize < pagesize and it is attached to the page straddling
    2334                 :            :          * EOF. Since the buffer might have been added to BJ_Forget list of the
    2335                 :            :          * running transaction, journal_get_write_access() won't clear
    2336                 :            :          * b_modified and credit accounting gets confused. So clear b_modified
    2337                 :            :          * here.
    2338                 :            :          */
    2339                 :          0 :         jh->b_modified = 0;
    2340                 :          0 :         jbd2_journal_put_journal_head(jh);
    2341                 :            : zap_buffer_no_jh:
    2342                 :            :         spin_unlock(&journal->j_list_lock);
    2343                 :            :         jbd_unlock_bh_state(bh);
    2344                 :            :         write_unlock(&journal->j_state_lock);
    2345                 :            : zap_buffer_unlocked:
    2346                 :            :         clear_buffer_dirty(bh);
    2347                 :          0 :         J_ASSERT_BH(bh, !buffer_jbddirty(bh));
    2348                 :            :         clear_buffer_mapped(bh);
    2349                 :            :         clear_buffer_req(bh);
    2350                 :            :         clear_buffer_new(bh);
    2351                 :            :         clear_buffer_delay(bh);
    2352                 :            :         clear_buffer_unwritten(bh);
    2353                 :          0 :         bh->b_bdev = NULL;
    2354                 :          0 :         return may_free;
    2355                 :            : }
    2356                 :            : 
    2357                 :            : /**
    2358                 :            :  * void jbd2_journal_invalidatepage()
    2359                 :            :  * @journal: journal to use for flush...
    2360                 :            :  * @page:    page to flush
    2361                 :            :  * @offset:  start of the range to invalidate
    2362                 :            :  * @length:  length of the range to invalidate
    2363                 :            :  *
    2364                 :            :  * Reap page buffers containing data after in the specified range in page.
    2365                 :            :  * Can return -EBUSY if buffers are part of the committing transaction and
    2366                 :            :  * the page is straddling i_size. Caller then has to wait for current commit
    2367                 :            :  * and try again.
    2368                 :            :  */
    2369                 :          0 : int jbd2_journal_invalidatepage(journal_t *journal,
    2370                 :            :                                 struct page *page,
    2371                 :            :                                 unsigned int offset,
    2372                 :            :                                 unsigned int length)
    2373                 :            : {
    2374                 :            :         struct buffer_head *head, *bh, *next;
    2375                 :          0 :         unsigned int stop = offset + length;
    2376                 :            :         unsigned int curr_off = 0;
    2377                 :          0 :         int partial_page = (offset || length < PAGE_SIZE);
    2378                 :            :         int may_free = 1;
    2379                 :            :         int ret = 0;
    2380                 :            : 
    2381                 :          0 :         if (!PageLocked(page))
    2382                 :          0 :                 BUG();
    2383                 :          0 :         if (!page_has_buffers(page))
    2384                 :            :                 return 0;
    2385                 :            : 
    2386                 :          0 :         BUG_ON(stop > PAGE_SIZE || stop < length);
    2387                 :            : 
    2388                 :            :         /* We will potentially be playing with lists other than just the
    2389                 :            :          * data lists (especially for journaled data mode), so be
    2390                 :            :          * cautious in our locking. */
    2391                 :            : 
    2392                 :          0 :         head = bh = page_buffers(page);
    2393                 :            :         do {
    2394                 :          0 :                 unsigned int next_off = curr_off + bh->b_size;
    2395                 :          0 :                 next = bh->b_this_page;
    2396                 :            : 
    2397                 :          0 :                 if (next_off > stop)
    2398                 :            :                         return 0;
    2399                 :            : 
    2400                 :          0 :                 if (offset <= curr_off) {
    2401                 :            :                         /* This block is wholly outside the truncation point */
    2402                 :          0 :                         lock_buffer(bh);
    2403                 :          0 :                         ret = journal_unmap_buffer(journal, bh, partial_page);
    2404                 :          0 :                         unlock_buffer(bh);
    2405                 :          0 :                         if (ret < 0)
    2406                 :          0 :                                 return ret;
    2407                 :          0 :                         may_free &= ret;
    2408                 :            :                 }
    2409                 :            :                 curr_off = next_off;
    2410                 :            :                 bh = next;
    2411                 :            : 
    2412                 :          0 :         } while (bh != head);
    2413                 :            : 
    2414                 :          0 :         if (!partial_page) {
    2415                 :          0 :                 if (may_free && try_to_free_buffers(page))
    2416                 :          0 :                         J_ASSERT(!page_has_buffers(page));
    2417                 :            :         }
    2418                 :            :         return 0;
    2419                 :            : }
    2420                 :            : 
    2421                 :            : /*
    2422                 :            :  * File a buffer on the given transaction list.
    2423                 :            :  */
    2424                 :          3 : void __jbd2_journal_file_buffer(struct journal_head *jh,
    2425                 :            :                         transaction_t *transaction, int jlist)
    2426                 :            : {
    2427                 :            :         struct journal_head **list = NULL;
    2428                 :            :         int was_dirty = 0;
    2429                 :            :         struct buffer_head *bh = jh2bh(jh);
    2430                 :            : 
    2431                 :          3 :         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
    2432                 :          3 :         assert_spin_locked(&transaction->t_journal->j_list_lock);
    2433                 :            : 
    2434                 :          3 :         J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
    2435                 :          3 :         J_ASSERT_JH(jh, jh->b_transaction == transaction ||
    2436                 :            :                                 jh->b_transaction == NULL);
    2437                 :            : 
    2438                 :          3 :         if (jh->b_transaction && jh->b_jlist == jlist)
    2439                 :            :                 return;
    2440                 :            : 
    2441                 :          3 :         if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
    2442                 :          3 :             jlist == BJ_Shadow || jlist == BJ_Forget) {
    2443                 :            :                 /*
    2444                 :            :                  * For metadata buffers, we track dirty bit in buffer_jbddirty
    2445                 :            :                  * instead of buffer_dirty. We should not see a dirty bit set
    2446                 :            :                  * here because we clear it in do_get_write_access but e.g.
    2447                 :            :                  * tune2fs can modify the sb and set the dirty bit at any time
    2448                 :            :                  * so we try to gracefully handle that.
    2449                 :            :                  */
    2450                 :          3 :                 if (buffer_dirty(bh))
    2451                 :            :                         warn_dirty_buffer(bh);
    2452                 :          3 :                 if (test_clear_buffer_dirty(bh) ||
    2453                 :            :                     test_clear_buffer_jbddirty(bh))
    2454                 :            :                         was_dirty = 1;
    2455                 :            :         }
    2456                 :            : 
    2457                 :          3 :         if (jh->b_transaction)
    2458                 :          3 :                 __jbd2_journal_temp_unlink_buffer(jh);
    2459                 :            :         else
    2460                 :          3 :                 jbd2_journal_grab_journal_head(bh);
    2461                 :          3 :         jh->b_transaction = transaction;
    2462                 :            : 
    2463                 :          3 :         switch (jlist) {
    2464                 :            :         case BJ_None:
    2465                 :          0 :                 J_ASSERT_JH(jh, !jh->b_committed_data);
    2466                 :          0 :                 J_ASSERT_JH(jh, !jh->b_frozen_data);
    2467                 :            :                 return;
    2468                 :            :         case BJ_Metadata:
    2469                 :          3 :                 transaction->t_nr_buffers++;
    2470                 :          3 :                 list = &transaction->t_buffers;
    2471                 :          3 :                 break;
    2472                 :            :         case BJ_Forget:
    2473                 :          3 :                 list = &transaction->t_forget;
    2474                 :          3 :                 break;
    2475                 :            :         case BJ_Shadow:
    2476                 :          3 :                 list = &transaction->t_shadow_list;
    2477                 :          3 :                 break;
    2478                 :            :         case BJ_Reserved:
    2479                 :          3 :                 list = &transaction->t_reserved_list;
    2480                 :          3 :                 break;
    2481                 :            :         }
    2482                 :            : 
    2483                 :            :         __blist_add_buffer(list, jh);
    2484                 :          3 :         jh->b_jlist = jlist;
    2485                 :            : 
    2486                 :          3 :         if (was_dirty)
    2487                 :            :                 set_buffer_jbddirty(bh);
    2488                 :            : }
    2489                 :            : 
    2490                 :          3 : void jbd2_journal_file_buffer(struct journal_head *jh,
    2491                 :            :                                 transaction_t *transaction, int jlist)
    2492                 :            : {
    2493                 :            :         jbd_lock_bh_state(jh2bh(jh));
    2494                 :          3 :         spin_lock(&transaction->t_journal->j_list_lock);
    2495                 :          3 :         __jbd2_journal_file_buffer(jh, transaction, jlist);
    2496                 :          3 :         spin_unlock(&transaction->t_journal->j_list_lock);
    2497                 :            :         jbd_unlock_bh_state(jh2bh(jh));
    2498                 :          3 : }
    2499                 :            : 
    2500                 :            : /*
    2501                 :            :  * Remove a buffer from its current buffer list in preparation for
    2502                 :            :  * dropping it from its current transaction entirely.  If the buffer has
    2503                 :            :  * already started to be used by a subsequent transaction, refile the
    2504                 :            :  * buffer on that transaction's metadata list.
    2505                 :            :  *
    2506                 :            :  * Called under j_list_lock
    2507                 :            :  * Called under jbd_lock_bh_state(jh2bh(jh))
    2508                 :            :  *
    2509                 :            :  * jh and bh may be already free when this function returns
    2510                 :            :  */
    2511                 :          3 : void __jbd2_journal_refile_buffer(struct journal_head *jh)
    2512                 :            : {
    2513                 :            :         int was_dirty, jlist;
    2514                 :            :         struct buffer_head *bh = jh2bh(jh);
    2515                 :            : 
    2516                 :          3 :         J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
    2517                 :          3 :         if (jh->b_transaction)
    2518                 :          3 :                 assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);
    2519                 :            : 
    2520                 :            :         /* If the buffer is now unused, just drop it. */
    2521                 :          3 :         if (jh->b_next_transaction == NULL) {
    2522                 :            :                 __jbd2_journal_unfile_buffer(jh);
    2523                 :          3 :                 return;
    2524                 :            :         }
    2525                 :            : 
    2526                 :            :         /*
    2527                 :            :          * It has been modified by a later transaction: add it to the new
    2528                 :            :          * transaction's metadata list.
    2529                 :            :          */
    2530                 :            : 
    2531                 :            :         was_dirty = test_clear_buffer_jbddirty(bh);
    2532                 :          3 :         __jbd2_journal_temp_unlink_buffer(jh);
    2533                 :            :         /*
    2534                 :            :          * We set b_transaction here because b_next_transaction will inherit
    2535                 :            :          * our jh reference and thus __jbd2_journal_file_buffer() must not
    2536                 :            :          * take a new one.
    2537                 :            :          */
    2538                 :          3 :         WRITE_ONCE(jh->b_transaction, jh->b_next_transaction);
    2539                 :            :         WRITE_ONCE(jh->b_next_transaction, NULL);
    2540                 :          3 :         if (buffer_freed(bh))
    2541                 :            :                 jlist = BJ_Forget;
    2542                 :          3 :         else if (jh->b_modified)
    2543                 :            :                 jlist = BJ_Metadata;
    2544                 :            :         else
    2545                 :            :                 jlist = BJ_Reserved;
    2546                 :          3 :         __jbd2_journal_file_buffer(jh, jh->b_transaction, jlist);
    2547                 :          3 :         J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);
    2548                 :            : 
    2549                 :          3 :         if (was_dirty)
    2550                 :            :                 set_buffer_jbddirty(bh);
    2551                 :            : }
    2552                 :            : 
    2553                 :            : /*
    2554                 :            :  * __jbd2_journal_refile_buffer() with necessary locking added. We take our
    2555                 :            :  * bh reference so that we can safely unlock bh.
    2556                 :            :  *
    2557                 :            :  * The jh and bh may be freed by this call.
    2558                 :            :  */
    2559                 :          0 : void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
    2560                 :            : {
    2561                 :            :         struct buffer_head *bh = jh2bh(jh);
    2562                 :            : 
    2563                 :            :         /* Get reference so that buffer cannot be freed before we unlock it */
    2564                 :            :         get_bh(bh);
    2565                 :            :         jbd_lock_bh_state(bh);
    2566                 :            :         spin_lock(&journal->j_list_lock);
    2567                 :          0 :         __jbd2_journal_refile_buffer(jh);
    2568                 :            :         jbd_unlock_bh_state(bh);
    2569                 :            :         spin_unlock(&journal->j_list_lock);
    2570                 :          0 :         __brelse(bh);
    2571                 :          0 : }
    2572                 :            : 
    2573                 :            : /*
    2574                 :            :  * File inode in the inode list of the handle's transaction
    2575                 :            :  */
    2576                 :          3 : static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
    2577                 :            :                 unsigned long flags, loff_t start_byte, loff_t end_byte)
    2578                 :            : {
    2579                 :          3 :         transaction_t *transaction = handle->h_transaction;
    2580                 :            :         journal_t *journal;
    2581                 :            : 
    2582                 :          3 :         if (is_handle_aborted(handle))
    2583                 :            :                 return -EROFS;
    2584                 :          3 :         journal = transaction->t_journal;
    2585                 :            : 
    2586                 :            :         jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
    2587                 :            :                         transaction->t_tid);
    2588                 :            : 
    2589                 :            :         spin_lock(&journal->j_list_lock);
    2590                 :          3 :         jinode->i_flags |= flags;
    2591                 :            : 
    2592                 :          3 :         if (jinode->i_dirty_end) {
    2593                 :          3 :                 jinode->i_dirty_start = min(jinode->i_dirty_start, start_byte);
    2594                 :          3 :                 jinode->i_dirty_end = max(jinode->i_dirty_end, end_byte);
    2595                 :            :         } else {
    2596                 :          3 :                 jinode->i_dirty_start = start_byte;
    2597                 :          3 :                 jinode->i_dirty_end = end_byte;
    2598                 :            :         }
    2599                 :            : 
    2600                 :            :         /* Is inode already attached where we need it? */
    2601                 :          3 :         if (jinode->i_transaction == transaction ||
    2602                 :          3 :             jinode->i_next_transaction == transaction)
    2603                 :            :                 goto done;
    2604                 :            : 
    2605                 :            :         /*
    2606                 :            :          * We only ever set this variable to 1 so the test is safe. Since
    2607                 :            :          * t_need_data_flush is likely to be set, we do the test to save some
    2608                 :            :          * cacheline bouncing
    2609                 :            :          */
    2610                 :          3 :         if (!transaction->t_need_data_flush)
    2611                 :          3 :                 transaction->t_need_data_flush = 1;
    2612                 :            :         /* On some different transaction's list - should be
    2613                 :            :          * the committing one */
    2614                 :          3 :         if (jinode->i_transaction) {
    2615                 :          0 :                 J_ASSERT(jinode->i_next_transaction == NULL);
    2616                 :          0 :                 J_ASSERT(jinode->i_transaction ==
    2617                 :            :                                         journal->j_committing_transaction);
    2618                 :          0 :                 jinode->i_next_transaction = transaction;
    2619                 :          0 :                 goto done;
    2620                 :            :         }
    2621                 :            :         /* Not on any transaction list... */
    2622                 :          3 :         J_ASSERT(!jinode->i_next_transaction);
    2623                 :          3 :         jinode->i_transaction = transaction;
    2624                 :          3 :         list_add(&jinode->i_list, &transaction->t_inode_list);
    2625                 :            : done:
    2626                 :            :         spin_unlock(&journal->j_list_lock);
    2627                 :            : 
    2628                 :          3 :         return 0;
    2629                 :            : }
    2630                 :            : 
    2631                 :          0 : int jbd2_journal_inode_ranged_write(handle_t *handle,
    2632                 :            :                 struct jbd2_inode *jinode, loff_t start_byte, loff_t length)
    2633                 :            : {
    2634                 :          0 :         return jbd2_journal_file_inode(handle, jinode,
    2635                 :            :                         JI_WRITE_DATA | JI_WAIT_DATA, start_byte,
    2636                 :          0 :                         start_byte + length - 1);
    2637                 :            : }
    2638                 :            : 
    2639                 :          3 : int jbd2_journal_inode_ranged_wait(handle_t *handle, struct jbd2_inode *jinode,
    2640                 :            :                 loff_t start_byte, loff_t length)
    2641                 :            : {
    2642                 :          3 :         return jbd2_journal_file_inode(handle, jinode, JI_WAIT_DATA,
    2643                 :          3 :                         start_byte, start_byte + length - 1);
    2644                 :            : }
    2645                 :            : 
    2646                 :            : /*
    2647                 :            :  * File truncate and transaction commit interact with each other in a
    2648                 :            :  * non-trivial way.  If a transaction writing data block A is
    2649                 :            :  * committing, we cannot discard the data by truncate until we have
    2650                 :            :  * written them.  Otherwise if we crashed after the transaction with
    2651                 :            :  * write has committed but before the transaction with truncate has
    2652                 :            :  * committed, we could see stale data in block A.  This function is a
    2653                 :            :  * helper to solve this problem.  It starts writeout of the truncated
    2654                 :            :  * part in case it is in the committing transaction.
    2655                 :            :  *
    2656                 :            :  * Filesystem code must call this function when inode is journaled in
    2657                 :            :  * ordered mode before truncation happens and after the inode has been
    2658                 :            :  * placed on orphan list with the new inode size. The second condition
    2659                 :            :  * avoids the race that someone writes new data and we start
    2660                 :            :  * committing the transaction after this function has been called but
    2661                 :            :  * before a transaction for truncate is started (and furthermore it
    2662                 :            :  * allows us to optimize the case where the addition to orphan list
    2663                 :            :  * happens in the same transaction as write --- we don't have to write
    2664                 :            :  * any data in such case).
    2665                 :            :  */
    2666                 :          3 : int jbd2_journal_begin_ordered_truncate(journal_t *journal,
    2667                 :            :                                         struct jbd2_inode *jinode,
    2668                 :            :                                         loff_t new_size)
    2669                 :            : {
    2670                 :            :         transaction_t *inode_trans, *commit_trans;
    2671                 :            :         int ret = 0;
    2672                 :            : 
    2673                 :            :         /* This is a quick check to avoid locking if not necessary */
    2674                 :          3 :         if (!jinode->i_transaction)
    2675                 :            :                 goto out;
    2676                 :            :         /* Locks are here just to force reading of recent values, it is
    2677                 :            :          * enough that the transaction was not committing before we started
    2678                 :            :          * a transaction adding the inode to orphan list */
    2679                 :          3 :         read_lock(&journal->j_state_lock);
    2680                 :          3 :         commit_trans = journal->j_committing_transaction;
    2681                 :            :         read_unlock(&journal->j_state_lock);
    2682                 :            :         spin_lock(&journal->j_list_lock);
    2683                 :          3 :         inode_trans = jinode->i_transaction;
    2684                 :            :         spin_unlock(&journal->j_list_lock);
    2685                 :          3 :         if (inode_trans == commit_trans) {
    2686                 :          0 :                 ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping,
    2687                 :            :                         new_size, LLONG_MAX);
    2688                 :          0 :                 if (ret)
    2689                 :          0 :                         jbd2_journal_abort(journal, ret);
    2690                 :            :         }
    2691                 :            : out:
    2692                 :          3 :         return ret;
    2693                 :            : }
    

Generated by: LCOV version 1.14