LCOV - code coverage report
Current view: top level - lkbce/fs/jbd - commit.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 0 504 0.0 %
Date: 2017-01-25 Functions: 0 8 0.0 %

          Line data    Source code
       1             : /*
       2             :  * linux/fs/jbd/commit.c
       3             :  *
       4             :  * Written by Stephen C. Tweedie <sct@redhat.com>, 1998
       5             :  *
       6             :  * Copyright 1998 Red Hat corp --- All Rights Reserved
       7             :  *
       8             :  * This file is part of the Linux kernel and is made available under
       9             :  * the terms of the GNU General Public License, version 2, or at your
      10             :  * option, any later version, incorporated herein by reference.
      11             :  *
      12             :  * Journal commit routines for the generic filesystem journaling code;
      13             :  * part of the ext2fs journaling system.
      14             :  */
      15             : 
      16             : #include <linux/time.h>
      17             : #include <linux/fs.h>
      18             : #include <linux/jbd.h>
      19             : #include <linux/errno.h>
      20             : #include <linux/slab.h>
      21             : #include <linux/mm.h>
      22             : #include <linux/pagemap.h>
      23             : #include <linux/bio.h>
      24             : 
      25             : /*
      26             :  * Default IO end handler for temporary BJ_IO buffer_heads.
      27             :  */
      28             : static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
      29             : {
      30             :         BUFFER_TRACE(bh, "");
      31           0 :         if (uptodate)
      32           0 :                 set_buffer_uptodate(bh);
      33             :         else
      34           0 :                 clear_buffer_uptodate(bh);
      35           0 :         unlock_buffer(bh);
      36           0 : }
      37             : 
      38             : /*
      39             :  * When an ext3-ordered file is truncated, it is possible that many pages are
      40             :  * not successfully freed, because they are attached to a committing transaction.
      41             :  * After the transaction commits, these pages are left on the LRU, with no
      42             :  * ->mapping, and with attached buffers.  These pages are trivially reclaimable
      43             :  * by the VM, but their apparent absence upsets the VM accounting, and it makes
      44             :  * the numbers in /proc/meminfo look odd.
      45             :  *
      46             :  * So here, we have a buffer which has just come off the forget list.  Look to
      47             :  * see if we can strip all buffers from the backing page.
      48             :  *
      49             :  * Called under journal->j_list_lock.  The caller provided us with a ref
      50             :  * against the buffer, and we drop that here.
      51             :  */
      52             : static void release_buffer_page(struct buffer_head *bh)
      53             : {
      54           0 :         struct page *page;
      55           0 : 
      56           0 :         if (buffer_dirty(bh))
      57           0 :                 goto nope;
      58           0 :         if (atomic_read(&bh->b_count) != 1)
      59           0 :                 goto nope;
      60           0 :         page = bh->b_page;
      61           0 :         if (!page)
      62           0 :                 goto nope;
      63           0 :         if (page->mapping)
      64           0 :                 goto nope;
      65             : 
      66             :         /* OK, it's a truncated page */
      67           0 :         if (!trylock_page(page))
      68           0 :                 goto nope;
      69             : 
      70           0 :         page_cache_get(page);
      71           0 :         __brelse(bh);
      72           0 :         try_to_free_buffers(page);
      73           0 :         unlock_page(page);
      74           0 :         page_cache_release(page);
      75           0 :         return;
      76           0 : 
      77             : nope:
      78           0 :         __brelse(bh);
      79           0 : }
      80             : 
      81             : /*
      82             :  * Decrement reference counter for data buffer. If it has been marked
      83             :  * 'BH_Freed', release it and the page to which it belongs if possible.
      84             :  */
      85             : static void release_data_buffer(struct buffer_head *bh)
      86             : {
      87           0 :         if (buffer_freed(bh)) {
      88           0 :                 clear_buffer_freed(bh);
      89           0 :                 release_buffer_page(bh);
      90             :         } else
      91           0 :                 put_bh(bh);
      92           0 : }
      93             : 
      94             : /*
      95             :  * Try to acquire jbd_lock_bh_state() against the buffer, when j_list_lock is
      96             :  * held.  For ranking reasons we must trylock.  If we lose, schedule away and
      97             :  * return 0.  j_list_lock is dropped in this case.
      98             :  */
      99             : static int inverted_lock(journal_t *journal, struct buffer_head *bh)
     100             : {
     101           0 :         if (!jbd_trylock_bh_state(bh)) {
     102           0 :                 spin_unlock(&journal->j_list_lock);
     103           0 :                 schedule();
     104           0 :                 return 0;
     105             :         }
     106           0 :         return 1;
     107             : }
     108             : 
     109             : /* Done it all: now write the commit record.  We should have
     110             :  * cleaned up our previous buffers by now, so if we are in abort
     111             :  * mode we can now just skip the rest of the journal write
     112             :  * entirely.
     113             :  *
     114             :  * Returns 1 if the journal needs to be aborted or 0 on success
     115             :  */
     116             : static int journal_write_commit_record(journal_t *journal,
     117             :                                         transaction_t *commit_transaction)
     118           0 : {
     119           0 :         struct journal_head *descriptor;
     120           0 :         struct buffer_head *bh;
     121           0 :         journal_header_t *header;
     122           0 :         int ret;
     123           0 :         int barrier_done = 0;
     124           0 : 
     125           0 :         if (is_journal_aborted(journal))
     126           0 :                 return 0;
     127             : 
     128           0 :         descriptor = journal_get_descriptor_buffer(journal);
     129           0 :         if (!descriptor)
     130           0 :                 return 1;
     131             : 
     132           0 :         bh = jh2bh(descriptor);
     133             : 
     134           0 :         header = (journal_header_t *)(bh->b_data);
     135           0 :         header->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER);
     136           0 :         header->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK);
     137           0 :         header->h_sequence = cpu_to_be32(commit_transaction->t_tid);
     138             : 
     139             :         JBUFFER_TRACE(descriptor, "write commit block");
     140           0 :         set_buffer_dirty(bh);
     141           0 :         if (journal->j_flags & JFS_BARRIER) {
     142           0 :                 set_buffer_ordered(bh);
     143           0 :                 barrier_done = 1;
     144             :         }
     145           0 :         ret = sync_dirty_buffer(bh);
     146           0 :         if (barrier_done)
     147           0 :                 clear_buffer_ordered(bh);
     148             :         /* is it possible for another commit to fail at roughly
     149             :          * the same time as this one?  If so, we don't want to
     150             :          * trust the barrier flag in the super, but instead want
     151             :          * to remember if we sent a barrier request
     152             :          */
     153           0 :         if (ret == -EOPNOTSUPP && barrier_done) {
     154             :                 char b[BDEVNAME_SIZE];
     155             : 
     156           0 :                 printk(KERN_WARNING
     157             :                         "JBD: barrier-based sync failed on %s - "
     158             :                         "disabling barriers\n",
     159             :                         bdevname(journal->j_dev, b));
     160           0 :                 spin_lock(&journal->j_state_lock);
     161           0 :                 journal->j_flags &= ~JFS_BARRIER;
     162           0 :                 spin_unlock(&journal->j_state_lock);
     163             : 
     164             :                 /* And try again, without the barrier */
     165           0 :                 set_buffer_uptodate(bh);
     166           0 :                 set_buffer_dirty(bh);
     167           0 :                 ret = sync_dirty_buffer(bh);
     168             :         }
     169           0 :         put_bh(bh);             /* One for getblk() */
     170           0 :         journal_put_journal_head(descriptor);
     171             : 
     172           0 :         return (ret == -EIO);
     173             : }
     174             : 
     175             : static void journal_do_submit_data(struct buffer_head **wbuf, int bufs,
     176             :                                    int write_op)
     177           0 : {
     178             :         int i;
     179             : 
     180           0 :         for (i = 0; i < bufs; i++) {
     181           0 :                 wbuf[i]->b_end_io = end_buffer_write_sync;
     182           0 :                 /* We use-up our safety reference in submit_bh() */
     183           0 :                 submit_bh(write_op, wbuf[i]);
     184             :         }
     185             : }
     186             : 
     187           0 : /*
     188             :  *  Submit all the data buffers to disk
     189             :  */
     190             : static int journal_submit_data_buffers(journal_t *journal,
     191             :                                        transaction_t *commit_transaction,
     192             :                                        int write_op)
     193           0 : {
     194           0 :         struct journal_head *jh;
     195           0 :         struct buffer_head *bh;
     196           0 :         int locked;
     197           0 :         int bufs = 0;
     198           0 :         struct buffer_head **wbuf = journal->j_wbuf;
     199           0 :         int err = 0;
     200           0 : 
     201           0 :         /*
     202           0 :          * Whenever we unlock the journal and sleep, things can get added
     203           0 :          * onto ->t_sync_datalist, so we have to keep looping back to
     204           0 :          * write_out_data until we *know* that the list is empty.
     205           0 :          *
     206           0 :          * Cleanup any flushed data buffers from the data list.  Even in
     207           0 :          * abort mode, we want to flush this out as soon as possible.
     208           0 :          */
     209           0 : write_out_data:
     210           0 :         cond_resched();
     211           0 :         spin_lock(&journal->j_list_lock);
     212             : 
     213           0 :         while (commit_transaction->t_sync_datalist) {
     214           0 :                 jh = commit_transaction->t_sync_datalist;
     215           0 :                 bh = jh2bh(jh);
     216           0 :                 locked = 0;
     217             : 
     218             :                 /* Get reference just to make sure buffer does not disappear
     219             :                  * when we are forced to drop various locks */
     220           0 :                 get_bh(bh);
     221             :                 /* If the buffer is dirty, we need to submit IO and hence
     222             :                  * we need the buffer lock. We try to lock the buffer without
     223             :                  * blocking. If we fail, we need to drop j_list_lock and do
     224             :                  * blocking lock_buffer().
     225             :                  */
     226           0 :                 if (buffer_dirty(bh)) {
     227           0 :                         if (!trylock_buffer(bh)) {
     228             :                                 BUFFER_TRACE(bh, "needs blocking lock");
     229           0 :                                 spin_unlock(&journal->j_list_lock);
     230             :                                 /* Write out all data to prevent deadlocks */
     231           0 :                                 journal_do_submit_data(wbuf, bufs, write_op);
     232           0 :                                 bufs = 0;
     233           0 :                                 lock_buffer(bh);
     234           0 :                                 spin_lock(&journal->j_list_lock);
     235             :                         }
     236           0 :                         locked = 1;
     237             :                 }
     238             :                 /* We have to get bh_state lock. Again out of order, sigh. */
     239           0 :                 if (!inverted_lock(journal, bh)) {
     240           0 :                         jbd_lock_bh_state(bh);
     241           0 :                         spin_lock(&journal->j_list_lock);
     242             :                 }
     243             :                 /* Someone already cleaned up the buffer? */
     244           0 :                 if (!buffer_jbd(bh) || bh2jh(bh) != jh
     245           0 :                         || jh->b_transaction != commit_transaction
     246             :                         || jh->b_jlist != BJ_SyncData) {
     247           0 :                         jbd_unlock_bh_state(bh);
     248           0 :                         if (locked)
     249           0 :                                 unlock_buffer(bh);
     250             :                         BUFFER_TRACE(bh, "already cleaned up");
     251           0 :                         release_data_buffer(bh);
     252           0 :                         continue;
     253             :                 }
     254           0 :                 if (locked && test_clear_buffer_dirty(bh)) {
     255             :                         BUFFER_TRACE(bh, "needs writeout, adding to array");
     256           0 :                         wbuf[bufs++] = bh;
     257           0 :                         __journal_file_buffer(jh, commit_transaction,
     258             :                                                 BJ_Locked);
     259           0 :                         jbd_unlock_bh_state(bh);
     260           0 :                         if (bufs == journal->j_wbufsize) {
     261           0 :                                 spin_unlock(&journal->j_list_lock);
     262           0 :                                 journal_do_submit_data(wbuf, bufs, write_op);
     263           0 :                                 bufs = 0;
     264           0 :                                 goto write_out_data;
     265             :                         }
     266           0 :                 } else if (!locked && buffer_locked(bh)) {
     267           0 :                         __journal_file_buffer(jh, commit_transaction,
     268             :                                                 BJ_Locked);
     269           0 :                         jbd_unlock_bh_state(bh);
     270           0 :                         put_bh(bh);
     271             :                 } else {
     272             :                         BUFFER_TRACE(bh, "writeout complete: unfile");
     273           0 :                         if (unlikely(!buffer_uptodate(bh)))
     274           0 :                                 err = -EIO;
     275           0 :                         __journal_unfile_buffer(jh);
     276           0 :                         jbd_unlock_bh_state(bh);
     277           0 :                         if (locked)
     278           0 :                                 unlock_buffer(bh);
     279           0 :                         journal_remove_journal_head(bh);
     280             :                         /* One for our safety reference, other for
     281             :                          * journal_remove_journal_head() */
     282           0 :                         put_bh(bh);
     283           0 :                         release_data_buffer(bh);
     284             :                 }
     285             : 
     286           0 :                 if (need_resched() || spin_needbreak(&journal->j_list_lock)) {
     287           0 :                         spin_unlock(&journal->j_list_lock);
     288           0 :                         goto write_out_data;
     289             :                 }
     290             :         }
     291           0 :         spin_unlock(&journal->j_list_lock);
     292           0 :         journal_do_submit_data(wbuf, bufs, write_op);
     293           0 : 
     294           0 :         return err;
     295             : }
     296             : 
     297             : /*
     298             :  * journal_commit_transaction
     299             :  *
     300             :  * The primary function for committing a transaction to the log.  This
     301             :  * function is called by the journal thread to begin a complete commit.
     302             :  */
     303             : void journal_commit_transaction(journal_t *journal)
     304             : {
     305           0 :         transaction_t *commit_transaction;
     306           0 :         struct journal_head *jh, *new_jh, *descriptor;
     307           0 :         struct buffer_head **wbuf = journal->j_wbuf;
     308           0 :         int bufs;
     309           0 :         int flags;
     310           0 :         int err;
     311           0 :         unsigned int blocknr;
     312           0 :         ktime_t start_time;
     313           0 :         u64 commit_time;
     314           0 :         char *tagp = NULL;
     315           0 :         journal_header_t *header;
     316           0 :         journal_block_tag_t *tag = NULL;
     317           0 :         int space_left = 0;
     318           0 :         int first_tag = 0;
     319           0 :         int tag_flag;
     320           0 :         int i;
     321           0 :         int write_op = WRITE;
     322           0 : 
     323           0 :         /*
     324           0 :          * First job: lock down the current transaction and wait for
     325           0 :          * all outstanding updates to complete.
     326           0 :          */
     327           0 : 
     328           0 : #ifdef COMMIT_STATS
     329           0 :         spin_lock(&journal->j_list_lock);
     330           0 :         summarise_journal_usage(journal);
     331           0 :         spin_unlock(&journal->j_list_lock);
     332           0 : #endif
     333           0 : 
     334           0 :         /* Do we need to erase the effects of a prior journal_flush? */
     335           0 :         if (journal->j_flags & JFS_FLUSHED) {
     336           0 :                 jbd_debug(3, "super block updated\n");
     337           0 :                 journal_update_superblock(journal, 1);
     338           0 :         } else {
     339           0 :                 jbd_debug(3, "superblock not updated\n");
     340           0 :         }
     341           0 : 
     342           0 :         J_ASSERT(journal->j_running_transaction != NULL);
     343           0 :         J_ASSERT(journal->j_committing_transaction == NULL);
     344           0 : 
     345           0 :         commit_transaction = journal->j_running_transaction;
     346           0 :         J_ASSERT(commit_transaction->t_state == T_RUNNING);
     347           0 : 
     348           0 :         jbd_debug(1, "JBD: starting commit of transaction %d\n",
     349           0 :                         commit_transaction->t_tid);
     350           0 : 
     351           0 :         spin_lock(&journal->j_state_lock);
     352           0 :         commit_transaction->t_state = T_LOCKED;
     353           0 : 
     354           0 :         /*
     355           0 :          * Use plugged writes here, since we want to submit several before
     356           0 :          * we unplug the device. We don't do explicit unplugging in here,
     357           0 :          * instead we rely on sync_buffer() doing the unplug for us.
     358           0 :          */
     359           0 :         if (commit_transaction->t_synchronous_commit)
     360           0 :                 write_op = WRITE_SYNC_PLUG;
     361           0 :         spin_lock(&commit_transaction->t_handle_lock);
     362           0 :         while (commit_transaction->t_updates) {
     363           0 :                 DEFINE_WAIT(wait);
     364           0 : 
     365           0 :                 prepare_to_wait(&journal->j_wait_updates, &wait,
     366           0 :                                         TASK_UNINTERRUPTIBLE);
     367           0 :                 if (commit_transaction->t_updates) {
     368           0 :                         spin_unlock(&commit_transaction->t_handle_lock);
     369           0 :                         spin_unlock(&journal->j_state_lock);
     370           0 :                         schedule();
     371           0 :                         spin_lock(&journal->j_state_lock);
     372           0 :                         spin_lock(&commit_transaction->t_handle_lock);
     373           0 :                 }
     374           0 :                 finish_wait(&journal->j_wait_updates, &wait);
     375           0 :         }
     376           0 :         spin_unlock(&commit_transaction->t_handle_lock);
     377           0 : 
     378           0 :         J_ASSERT (commit_transaction->t_outstanding_credits <=
     379           0 :                         journal->j_max_transaction_buffers);
     380           0 : 
     381           0 :         /*
     382           0 :          * First thing we are allowed to do is to discard any remaining
     383           0 :          * BJ_Reserved buffers.  Note, it is _not_ permissible to assume
     384           0 :          * that there are no such buffers: if a large filesystem
     385           0 :          * operation like a truncate needs to split itself over multiple
     386           0 :          * transactions, then it may try to do a journal_restart() while
     387           0 :          * there are still BJ_Reserved buffers outstanding.  These must
     388           0 :          * be released cleanly from the current transaction.
     389           0 :          *
     390           0 :          * In this case, the filesystem must still reserve write access
     391           0 :          * again before modifying the buffer in the new transaction, but
     392           0 :          * we do not require it to remember exactly which old buffers it
     393           0 :          * has reserved.  This is consistent with the existing behaviour
     394             :          * that multiple journal_get_write_access() calls to the same
     395             :          * buffer are perfectly permissable.
     396             :          */
     397           0 :         while (commit_transaction->t_reserved_list) {
     398           0 :                 jh = commit_transaction->t_reserved_list;
     399           0 :                 JBUFFER_TRACE(jh, "reserved, unused: refile");
     400             :                 /*
     401             :                  * A journal_get_undo_access()+journal_release_buffer() may
     402             :                  * leave undo-committed data.
     403             :                  */
     404           0 :                 if (jh->b_committed_data) {
     405           0 :                         struct buffer_head *bh = jh2bh(jh);
     406             : 
     407           0 :                         jbd_lock_bh_state(bh);
     408           0 :                         jbd_free(jh->b_committed_data, bh->b_size);
     409           0 :                         jh->b_committed_data = NULL;
     410           0 :                         jbd_unlock_bh_state(bh);
     411             :                 }
     412           0 :                 journal_refile_buffer(journal, jh);
     413             :         }
     414           0 : 
     415             :         /*
     416             :          * Now try to drop any written-back buffers from the journal's
     417             :          * checkpoint lists.  We do this *before* commit because it potentially
     418             :          * frees some memory
     419             :          */
     420           0 :         spin_lock(&journal->j_list_lock);
     421           0 :         __journal_clean_checkpoint_list(journal);
     422           0 :         spin_unlock(&journal->j_list_lock);
     423             : 
     424             :         jbd_debug (3, "JBD: commit phase 1\n");
     425             : 
     426             :         /*
     427             :          * Switch to a new revoke table.
     428             :          */
     429           0 :         journal_switch_revoke_table(journal);
     430             : 
     431           0 :         commit_transaction->t_state = T_FLUSH;
     432           0 :         journal->j_committing_transaction = commit_transaction;
     433           0 :         journal->j_running_transaction = NULL;
     434           0 :         start_time = ktime_get();
     435           0 :         commit_transaction->t_log_start = journal->j_head;
     436           0 :         wake_up(&journal->j_wait_transaction_locked);
     437           0 :         spin_unlock(&journal->j_state_lock);
     438             : 
     439             :         jbd_debug (3, "JBD: commit phase 2\n");
     440             : 
     441             :         /*
     442             :          * Now start flushing things to disk, in the order they appear
     443             :          * on the transaction lists.  Data blocks go first.
     444             :          */
     445           0 :         err = journal_submit_data_buffers(journal, commit_transaction,
     446             :                                           write_op);
     447             : 
     448             :         /*
     449             :          * Wait for all previously submitted IO to complete.
     450             :          */
     451           0 :         spin_lock(&journal->j_list_lock);
     452           0 :         while (commit_transaction->t_locked_list) {
     453           0 :                 struct buffer_head *bh;
     454           0 : 
     455           0 :                 jh = commit_transaction->t_locked_list->b_tprev;
     456           0 :                 bh = jh2bh(jh);
     457           0 :                 get_bh(bh);
     458           0 :                 if (buffer_locked(bh)) {
     459           0 :                         spin_unlock(&journal->j_list_lock);
     460           0 :                         wait_on_buffer(bh);
     461           0 :                         spin_lock(&journal->j_list_lock);
     462             :                 }
     463           0 :                 if (unlikely(!buffer_uptodate(bh))) {
     464           0 :                         if (!trylock_page(bh->b_page)) {
     465           0 :                                 spin_unlock(&journal->j_list_lock);
     466           0 :                                 lock_page(bh->b_page);
     467           0 :                                 spin_lock(&journal->j_list_lock);
     468             :                         }
     469           0 :                         if (bh->b_page->mapping)
     470           0 :                                 set_bit(AS_EIO, &bh->b_page->mapping->flags);
     471             : 
     472           0 :                         unlock_page(bh->b_page);
     473           0 :                         SetPageError(bh->b_page);
     474           0 :                         err = -EIO;
     475             :                 }
     476           0 :                 if (!inverted_lock(journal, bh)) {
     477           0 :                         put_bh(bh);
     478           0 :                         spin_lock(&journal->j_list_lock);
     479           0 :                         continue;
     480             :                 }
     481           0 :                 if (buffer_jbd(bh) && bh2jh(bh) == jh &&
     482             :                     jh->b_transaction == commit_transaction &&
     483             :                     jh->b_jlist == BJ_Locked) {
     484           0 :                         __journal_unfile_buffer(jh);
     485           0 :                         jbd_unlock_bh_state(bh);
     486           0 :                         journal_remove_journal_head(bh);
     487           0 :                         put_bh(bh);
     488             :                 } else {
     489           0 :                         jbd_unlock_bh_state(bh);
     490             :                 }
     491           0 :                 release_data_buffer(bh);
     492           0 :                 cond_resched_lock(&journal->j_list_lock);
     493             :         }
     494           0 :         spin_unlock(&journal->j_list_lock);
     495             : 
     496           0 :         if (err) {
     497             :                 char b[BDEVNAME_SIZE];
     498             : 
     499           0 :                 printk(KERN_WARNING
     500             :                         "JBD: Detected IO errors while flushing file data "
     501             :                         "on %s\n", bdevname(journal->j_fs_dev, b));
     502           0 :                 if (journal->j_flags & JFS_ABORT_ON_SYNCDATA_ERR)
     503           0 :                         journal_abort(journal, err);
     504           0 :                 err = 0;
     505             :         }
     506             : 
     507           0 :         journal_write_revoke_records(journal, commit_transaction, write_op);
     508             : 
     509             :         /*
     510             :          * If we found any dirty or locked buffers, then we should have
     511             :          * looped back up to the write_out_data label.  If there weren't
     512             :          * any then journal_clean_data_list should have wiped the list
     513             :          * clean by now, so check that it is in fact empty.
     514             :          */
     515           0 :         J_ASSERT (commit_transaction->t_sync_datalist == NULL);
     516             : 
     517             :         jbd_debug (3, "JBD: commit phase 3\n");
     518             : 
     519             :         /*
     520             :          * Way to go: we have now written out all of the data for a
     521             :          * transaction!  Now comes the tricky part: we need to write out
     522             :          * metadata.  Loop over the transaction's entire buffer list:
     523             :          */
     524           0 :         spin_lock(&journal->j_state_lock);
     525           0 :         commit_transaction->t_state = T_COMMIT;
     526           0 :         spin_unlock(&journal->j_state_lock);
     527             : 
     528           0 :         J_ASSERT(commit_transaction->t_nr_buffers <=
     529             :                  commit_transaction->t_outstanding_credits);
     530             : 
     531           0 :         descriptor = NULL;
     532           0 :         bufs = 0;
     533           0 :         while (commit_transaction->t_buffers) {
     534           0 : 
     535           0 :                 /* Find the next buffer to be journaled... */
     536             : 
     537           0 :                 jh = commit_transaction->t_buffers;
     538             : 
     539             :                 /* If we're in abort mode, we just un-journal the buffer and
     540           0 :                    release it. */
     541             : 
     542           0 :                 if (is_journal_aborted(journal)) {
     543           0 :                         clear_buffer_jbddirty(jh2bh(jh));
     544             :                         JBUFFER_TRACE(jh, "journal is aborting: refile");
     545           0 :                         journal_refile_buffer(journal, jh);
     546             :                         /* If that was the last one, we need to clean up
     547             :                          * any descriptor buffers which may have been
     548             :                          * already allocated, even if we are now
     549             :                          * aborting. */
     550           0 :                         if (!commit_transaction->t_buffers)
     551           0 :                                 goto start_journal_io;
     552           0 :                         continue;
     553             :                 }
     554             : 
     555             :                 /* Make sure we have a descriptor block in which to
     556             :                    record the metadata buffer. */
     557             : 
     558           0 :                 if (!descriptor) {
     559             :                         struct buffer_head *bh;
     560             : 
     561           0 :                         J_ASSERT (bufs == 0);
     562             : 
     563             :                         jbd_debug(4, "JBD: get descriptor\n");
     564             : 
     565           0 :                         descriptor = journal_get_descriptor_buffer(journal);
     566           0 :                         if (!descriptor) {
     567           0 :                                 journal_abort(journal, -EIO);
     568           0 :                                 continue;
     569             :                         }
     570             : 
     571           0 :                         bh = jh2bh(descriptor);
     572             :                         jbd_debug(4, "JBD: got buffer %llu (%p)\n",
     573             :                                 (unsigned long long)bh->b_blocknr, bh->b_data);
     574           0 :                         header = (journal_header_t *)&bh->b_data[0];
     575           0 :                         header->h_magic     = cpu_to_be32(JFS_MAGIC_NUMBER);
     576           0 :                         header->h_blocktype = cpu_to_be32(JFS_DESCRIPTOR_BLOCK);
     577           0 :                         header->h_sequence  = cpu_to_be32(commit_transaction->t_tid);
     578             : 
     579           0 :                         tagp = &bh->b_data[sizeof(journal_header_t)];
     580           0 :                         space_left = bh->b_size - sizeof(journal_header_t);
     581           0 :                         first_tag = 1;
     582           0 :                         set_buffer_jwrite(bh);
     583           0 :                         set_buffer_dirty(bh);
     584           0 :                         wbuf[bufs++] = bh;
     585             : 
     586             :                         /* Record it so that we can wait for IO
     587             :                            completion later */
     588             :                         BUFFER_TRACE(bh, "ph3: file as descriptor");
     589           0 :                         journal_file_buffer(descriptor, commit_transaction,
     590             :                                         BJ_LogCtl);
     591             :                 }
     592             : 
     593             :                 /* Where is the buffer to be written? */
     594             : 
     595           0 :                 err = journal_next_log_block(journal, &blocknr);
     596             :                 /* If the block mapping failed, just abandon the buffer
     597             :                    and repeat this loop: we'll fall into the
     598             :                    refile-on-abort condition above. */
     599           0 :                 if (err) {
     600           0 :                         journal_abort(journal, err);
     601           0 :                         continue;
     602             :                 }
     603             : 
     604             :                 /*
     605             :                  * start_this_handle() uses t_outstanding_credits to determine
     606             :                  * the free space in the log, but this counter is changed
     607             :                  * by journal_next_log_block() also.
     608             :                  */
     609           0 :                 commit_transaction->t_outstanding_credits--;
     610             : 
     611             :                 /* Bump b_count to prevent truncate from stumbling over
     612             :                    the shadowed buffer!  @@@ This can go if we ever get
     613             :                    rid of the BJ_IO/BJ_Shadow pairing of buffers. */
     614           0 :                 atomic_inc(&jh2bh(jh)->b_count);
     615             : 
     616             :                 /* Make a temporary IO buffer with which to write it out
     617             :                    (this will requeue both the metadata buffer and the
     618             :                    temporary IO buffer). new_bh goes on BJ_IO*/
     619             : 
     620           0 :                 set_bit(BH_JWrite, &jh2bh(jh)->b_state);
     621             :                 /*
     622             :                  * akpm: journal_write_metadata_buffer() sets
     623             :                  * new_bh->b_transaction to commit_transaction.
     624             :                  * We need to clean this up before we release new_bh
     625             :                  * (which is of type BJ_IO)
     626             :                  */
     627             :                 JBUFFER_TRACE(jh, "ph3: write metadata");
     628           0 :                 flags = journal_write_metadata_buffer(commit_transaction,
     629             :                                                       jh, &new_jh, blocknr);
     630           0 :                 set_bit(BH_JWrite, &jh2bh(new_jh)->b_state);
     631           0 :                 wbuf[bufs++] = jh2bh(new_jh);
     632             : 
     633             :                 /* Record the new block's tag in the current descriptor
     634             :                    buffer */
     635             : 
     636           0 :                 tag_flag = 0;
     637           0 :                 if (flags & 1)
     638           0 :                         tag_flag |= JFS_FLAG_ESCAPE;
     639           0 :                 if (!first_tag)
     640           0 :                         tag_flag |= JFS_FLAG_SAME_UUID;
     641             : 
     642           0 :                 tag = (journal_block_tag_t *) tagp;
     643           0 :                 tag->t_blocknr = cpu_to_be32(jh2bh(jh)->b_blocknr);
     644           0 :                 tag->t_flags = cpu_to_be32(tag_flag);
     645           0 :                 tagp += sizeof(journal_block_tag_t);
     646           0 :                 space_left -= sizeof(journal_block_tag_t);
     647             : 
     648           0 :                 if (first_tag) {
     649           0 :                         memcpy (tagp, journal->j_uuid, 16);
     650           0 :                         tagp += 16;
     651           0 :                         space_left -= 16;
     652           0 :                         first_tag = 0;
     653             :                 }
     654             : 
     655             :                 /* If there's no more to do, or if the descriptor is full,
     656             :                    let the IO rip! */
     657             : 
     658           0 :                 if (bufs == journal->j_wbufsize ||
     659             :                     commit_transaction->t_buffers == NULL ||
     660             :                     space_left < sizeof(journal_block_tag_t) + 16) {
     661             : 
     662             :                         jbd_debug(4, "JBD: Submit %d IOs\n", bufs);
     663             : 
     664             :                         /* Write an end-of-descriptor marker before
     665             :                            submitting the IOs.  "tag" still points to
     666             :                            the last tag we set up. */
     667             : 
     668           0 :                         tag->t_flags |= cpu_to_be32(JFS_FLAG_LAST_TAG);
     669           0 : 
     670             : start_journal_io:
     671           0 :                         for (i = 0; i < bufs; i++) {
     672           0 :                                 struct buffer_head *bh = wbuf[i];
     673           0 :                                 lock_buffer(bh);
     674           0 :                                 clear_buffer_dirty(bh);
     675           0 :                                 set_buffer_uptodate(bh);
     676           0 :                                 bh->b_end_io = journal_end_buffer_io_sync;
     677           0 :                                 submit_bh(write_op, bh);
     678             :                         }
     679           0 :                         cond_resched();
     680             : 
     681             :                         /* Force a new descriptor to be generated next
     682             :                            time round the loop. */
     683           0 :                         descriptor = NULL;
     684           0 :                         bufs = 0;
     685             :                 }
     686             :         }
     687             : 
     688             :         /* Lo and behold: we have just managed to send a transaction to
     689           0 :            the log.  Before we can commit it, wait for the IO so far to
     690             :            complete.  Control buffers being written are on the
     691             :            transaction's t_log_list queue, and metadata buffers are on
     692             :            the t_iobuf_list queue.
     693             : 
     694             :            Wait for the buffers in reverse order.  That way we are
     695             :            less likely to be woken up until all IOs have completed, and
     696             :            so we incur less scheduling load.
     697             :         */
     698             : 
     699             :         jbd_debug(3, "JBD: commit phase 4\n");
     700             : 
     701             :         /*
     702             :          * akpm: these are BJ_IO, and j_list_lock is not needed.
     703             :          * See __journal_try_to_free_buffer.
     704             :          */
     705             : wait_for_iobuf:
     706           0 :         while (commit_transaction->t_iobuf_list != NULL) {
     707           0 :                 struct buffer_head *bh;
     708           0 : 
     709           0 :                 jh = commit_transaction->t_iobuf_list->b_tprev;
     710           0 :                 bh = jh2bh(jh);
     711           0 :                 if (buffer_locked(bh)) {
     712           0 :                         wait_on_buffer(bh);
     713           0 :                         goto wait_for_iobuf;
     714             :                 }
     715           0 :                 if (cond_resched())
     716           0 :                         goto wait_for_iobuf;
     717             : 
     718           0 :                 if (unlikely(!buffer_uptodate(bh)))
     719           0 :                         err = -EIO;
     720             : 
     721           0 :                 clear_buffer_jwrite(bh);
     722             : 
     723             :                 JBUFFER_TRACE(jh, "ph4: unfile after journal write");
     724           0 :                 journal_unfile_buffer(journal, jh);
     725             : 
     726             :                 /*
     727             :                  * ->t_iobuf_list should contain only dummy buffer_heads
     728             :                  * which were created by journal_write_metadata_buffer().
     729             :                  */
     730             :                 BUFFER_TRACE(bh, "dumping temporary bh");
     731           0 :                 journal_put_journal_head(jh);
     732           0 :                 __brelse(bh);
     733           0 :                 J_ASSERT_BH(bh, atomic_read(&bh->b_count) == 0);
     734           0 :                 free_buffer_head(bh);
     735             : 
     736             :                 /* We also have to unlock and free the corresponding
     737             :                    shadowed buffer */
     738           0 :                 jh = commit_transaction->t_shadow_list->b_tprev;
     739           0 :                 bh = jh2bh(jh);
     740           0 :                 clear_bit(BH_JWrite, &bh->b_state);
     741           0 :                 J_ASSERT_BH(bh, buffer_jbddirty(bh));
     742             : 
     743             :                 /* The metadata is now released for reuse, but we need
     744             :                    to remember it against this transaction so that when
     745             :                    we finally commit, we can do any checkpointing
     746             :                    required. */
     747             :                 JBUFFER_TRACE(jh, "file as BJ_Forget");
     748           0 :                 journal_file_buffer(jh, commit_transaction, BJ_Forget);
     749             :                 /*
     750             :                  * Wake up any transactions which were waiting for this
     751             :                  * IO to complete. The barrier must be here so that changes
     752             :                  * by journal_file_buffer() take effect before wake_up_bit()
     753             :                  * does the waitqueue check.
     754             :                  */
     755           0 :                 smp_mb();
     756           0 :                 wake_up_bit(&bh->b_state, BH_Unshadow);
     757             :                 JBUFFER_TRACE(jh, "brelse shadowed buffer");
     758           0 :                 __brelse(bh);
     759             :         }
     760           0 : 
     761           0 :         J_ASSERT (commit_transaction->t_shadow_list == NULL);
     762             : 
     763             :         jbd_debug(3, "JBD: commit phase 5\n");
     764             : 
     765             :         /* Here we wait for the revoke record and descriptor record buffers */
     766           0 :  wait_for_ctlbuf:
     767           0 :         while (commit_transaction->t_log_list != NULL) {
     768           0 :                 struct buffer_head *bh;
     769           0 : 
     770           0 :                 jh = commit_transaction->t_log_list->b_tprev;
     771           0 :                 bh = jh2bh(jh);
     772           0 :                 if (buffer_locked(bh)) {
     773           0 :                         wait_on_buffer(bh);
     774           0 :                         goto wait_for_ctlbuf;
     775             :                 }
     776           0 :                 if (cond_resched())
     777           0 :                         goto wait_for_ctlbuf;
     778             : 
     779           0 :                 if (unlikely(!buffer_uptodate(bh)))
     780           0 :                         err = -EIO;
     781             : 
     782             :                 BUFFER_TRACE(bh, "ph5: control buffer writeout done: unfile");
     783           0 :                 clear_buffer_jwrite(bh);
     784           0 :                 journal_unfile_buffer(journal, jh);
     785           0 :                 journal_put_journal_head(jh);
     786           0 :                 __brelse(bh);           /* One for getblk */
     787             :                 /* AKPM: bforget here */
     788           0 :         }
     789             : 
     790           0 :         if (err)
     791           0 :                 journal_abort(journal, err);
     792             : 
     793             :         jbd_debug(3, "JBD: commit phase 6\n");
     794             : 
     795           0 :         if (journal_write_commit_record(journal, commit_transaction))
     796           0 :                 err = -EIO;
     797             : 
     798           0 :         if (err)
     799           0 :                 journal_abort(journal, err);
     800             : 
     801             :         /* End of a transaction!  Finally, we can do checkpoint
     802             :            processing: any buffers committed as a result of this
     803             :            transaction can be removed from any checkpoint list it was on
     804             :            before. */
     805             : 
     806             :         jbd_debug(3, "JBD: commit phase 7\n");
     807             : 
     808           0 :         J_ASSERT(commit_transaction->t_sync_datalist == NULL);
     809           0 :         J_ASSERT(commit_transaction->t_buffers == NULL);
     810           0 :         J_ASSERT(commit_transaction->t_checkpoint_list == NULL);
     811           0 :         J_ASSERT(commit_transaction->t_iobuf_list == NULL);
     812           0 :         J_ASSERT(commit_transaction->t_shadow_list == NULL);
     813           0 :         J_ASSERT(commit_transaction->t_log_list == NULL);
     814             : 
     815             : restart_loop:
     816             :         /*
     817             :          * As there are other places (journal_unmap_buffer()) adding buffers
     818           0 :          * to this list we have to be careful and hold the j_list_lock.
     819             :          */
     820           0 :         spin_lock(&journal->j_list_lock);
     821           0 :         while (commit_transaction->t_forget) {
     822           0 :                 transaction_t *cp_transaction;
     823           0 :                 struct buffer_head *bh;
     824             : 
     825           0 :                 jh = commit_transaction->t_forget;
     826           0 :                 spin_unlock(&journal->j_list_lock);
     827           0 :                 bh = jh2bh(jh);
     828           0 :                 jbd_lock_bh_state(bh);
     829           0 :                 J_ASSERT_JH(jh, jh->b_transaction == commit_transaction ||
     830             :                         jh->b_transaction == journal->j_running_transaction);
     831             : 
     832             :                 /*
     833             :                  * If there is undo-protected committed data against
     834             :                  * this buffer, then we can remove it now.  If it is a
     835             :                  * buffer needing such protection, the old frozen_data
     836             :                  * field now points to a committed version of the
     837             :                  * buffer, so rotate that field to the new committed
     838             :                  * data.
     839             :                  *
     840             :                  * Otherwise, we can just throw away the frozen data now.
     841             :                  */
     842           0 :                 if (jh->b_committed_data) {
     843           0 :                         jbd_free(jh->b_committed_data, bh->b_size);
     844           0 :                         jh->b_committed_data = NULL;
     845           0 :                         if (jh->b_frozen_data) {
     846           0 :                                 jh->b_committed_data = jh->b_frozen_data;
     847           0 :                                 jh->b_frozen_data = NULL;
     848             :                         }
     849           0 :                 } else if (jh->b_frozen_data) {
     850           0 :                         jbd_free(jh->b_frozen_data, bh->b_size);
     851           0 :                         jh->b_frozen_data = NULL;
     852             :                 }
     853             : 
     854           0 :                 spin_lock(&journal->j_list_lock);
     855           0 :                 cp_transaction = jh->b_cp_transaction;
     856           0 :                 if (cp_transaction) {
     857             :                         JBUFFER_TRACE(jh, "remove from old cp transaction");
     858           0 :                         __journal_remove_checkpoint(jh);
     859             :                 }
     860             : 
     861             :                 /* Only re-checkpoint the buffer_head if it is marked
     862             :                  * dirty.  If the buffer was added to the BJ_Forget list
     863             :                  * by journal_forget, it may no longer be dirty and
     864             :                  * there's no point in keeping a checkpoint record for
     865             :                  * it. */
     866             : 
     867             :                 /* A buffer which has been freed while still being
     868             :                  * journaled by a previous transaction may end up still
     869             :                  * being dirty here, but we want to avoid writing back
     870             :                  * that buffer in the future now that the last use has
     871             :                  * been committed.  That's not only a performance gain,
     872             :                  * it also stops aliasing problems if the buffer is left
     873             :                  * behind for writeback and gets reallocated for another
     874             :                  * use in a different page. */
     875           0 :                 if (buffer_freed(bh)) {
     876           0 :                         clear_buffer_freed(bh);
     877           0 :                         clear_buffer_jbddirty(bh);
     878             :                 }
     879             : 
     880           0 :                 if (buffer_jbddirty(bh)) {
     881             :                         JBUFFER_TRACE(jh, "add to new checkpointing trans");
     882           0 :                         __journal_insert_checkpoint(jh, commit_transaction);
     883           0 :                         if (is_journal_aborted(journal))
     884           0 :                                 clear_buffer_jbddirty(bh);
     885             :                         JBUFFER_TRACE(jh, "refile for checkpoint writeback");
     886           0 :                         __journal_refile_buffer(jh);
     887           0 :                         jbd_unlock_bh_state(bh);
     888             :                 } else {
     889           0 :                         J_ASSERT_BH(bh, !buffer_dirty(bh));
     890             :                         /* The buffer on BJ_Forget list and not jbddirty means
     891             :                          * it has been freed by this transaction and hence it
     892             :                          * could not have been reallocated until this
     893             :                          * transaction has committed. *BUT* it could be
     894             :                          * reallocated once we have written all the data to
     895             :                          * disk and before we process the buffer on BJ_Forget
     896             :                          * list. */
     897             :                         JBUFFER_TRACE(jh, "refile or unfile freed buffer");
     898           0 :                         __journal_refile_buffer(jh);
     899           0 :                         if (!jh->b_transaction) {
     900           0 :                                 jbd_unlock_bh_state(bh);
     901             :                                  /* needs a brelse */
     902           0 :                                 journal_remove_journal_head(bh);
     903           0 :                                 release_buffer_page(bh);
     904             :                         } else
     905           0 :                                 jbd_unlock_bh_state(bh);
     906             :                 }
     907           0 :                 cond_resched_lock(&journal->j_list_lock);
     908             :         }
     909           0 :         spin_unlock(&journal->j_list_lock);
     910             :         /*
     911             :          * This is a bit sleazy.  We use j_list_lock to protect transition
     912             :          * of a transaction into T_FINISHED state and calling
     913             :          * __journal_drop_transaction(). Otherwise we could race with
     914             :          * other checkpointing code processing the transaction...
     915             :          */
     916           0 :         spin_lock(&journal->j_state_lock);
     917           0 :         spin_lock(&journal->j_list_lock);
     918             :         /*
     919             :          * Now recheck if some buffers did not get attached to the transaction
     920             :          * while the lock was dropped...
     921             :          */
     922           0 :         if (commit_transaction->t_forget) {
     923           0 :                 spin_unlock(&journal->j_list_lock);
     924           0 :                 spin_unlock(&journal->j_state_lock);
     925           0 :                 goto restart_loop;
     926             :         }
     927             : 
     928             :         /* Done with this transaction! */
     929             : 
     930             :         jbd_debug(3, "JBD: commit phase 8\n");
     931             : 
     932           0 :         J_ASSERT(commit_transaction->t_state == T_COMMIT);
     933             : 
     934           0 :         commit_transaction->t_state = T_FINISHED;
     935           0 :         J_ASSERT(commit_transaction == journal->j_committing_transaction);
     936           0 :         journal->j_commit_sequence = commit_transaction->t_tid;
     937           0 :         journal->j_committing_transaction = NULL;
     938           0 :         commit_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
     939             : 
     940             :         /*
     941             :          * weight the commit time higher than the average time so we don't
     942             :          * react too strongly to vast changes in commit time
     943             :          */
     944           0 :         if (likely(journal->j_average_commit_time))
     945           0 :                 journal->j_average_commit_time = (commit_time*3 +
     946             :                                 journal->j_average_commit_time) / 4;
     947             :         else
     948           0 :                 journal->j_average_commit_time = commit_time;
     949             : 
     950           0 :         spin_unlock(&journal->j_state_lock);
     951             : 
     952           0 :         if (commit_transaction->t_checkpoint_list == NULL &&
     953             :             commit_transaction->t_checkpoint_io_list == NULL) {
     954           0 :                 __journal_drop_transaction(journal, commit_transaction);
     955             :         } else {
     956           0 :                 if (journal->j_checkpoint_transactions == NULL) {
     957           0 :                         journal->j_checkpoint_transactions = commit_transaction;
     958           0 :                         commit_transaction->t_cpnext = commit_transaction;
     959           0 :                         commit_transaction->t_cpprev = commit_transaction;
     960             :                 } else {
     961           0 :                         commit_transaction->t_cpnext =
     962             :                                 journal->j_checkpoint_transactions;
     963           0 :                         commit_transaction->t_cpprev =
     964             :                                 commit_transaction->t_cpnext->t_cpprev;
     965           0 :                         commit_transaction->t_cpnext->t_cpprev =
     966             :                                 commit_transaction;
     967           0 :                         commit_transaction->t_cpprev->t_cpnext =
     968             :                                 commit_transaction;
     969             :                 }
     970             :         }
     971           0 :         spin_unlock(&journal->j_list_lock);
     972             : 
     973             :         jbd_debug(1, "JBD: commit %d complete, head %d\n",
     974             :                   journal->j_commit_sequence, journal->j_tail_sequence);
     975             : 
     976           0 :         wake_up(&journal->j_wait_done_commit);
     977           0 : }

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