jbd2-abort-instead-of-waiting-for-nonexistent-transactions

   1 jbd2: abort instead of waiting for nonexistent transaction
   2
   3 The __jbd2_log_wait_for_space function sits in a loop checkpointing
   4 transactions until there is sufficient space free in the journal.
   5 However, if there are no transactions to be processed (e.g.  because the
   6 free space calculation is wrong due to a corrupted filesystem) it will
   7 never progress.
   8
   9 Check for space being required when no transactions are outstanding and
  10 abort the journal instead of endlessly looping.
  11
  12 This patch fixes the bug reported by Sami Liedes at:
  13 http://bugzilla.kernel.org/show_bug.cgi?id=10976
  14
  15 Signed-off-by: Duane Griffin <duaneg@dghda.com>
  16 Cc: Sami Liedes <sliedes@cc.hut.fi>
  17 Cc: <linux-ext4@vger.kernel.org>
  18 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  19 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  20 diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
  21 index 91389c8..af4651b 100644
  22 --- a/fs/jbd2/checkpoint.c
  23 +++ b/fs/jbd2/checkpoint.c
  24 @@ -126,14 +126,29 @@ void __jbd2_log_wait_for_space(journal_t *journal)
  25
  26                 /*
  27                  * Test again, another process may have checkpointed while we
  28 -                * were waiting for the checkpoint lock
  29 +                * were waiting for the checkpoint lock. If there are no
  30 +                * outstanding transactions there is nothing to checkpoint and
  31 +                * we can't make progress. Abort the journal in this case.
  32                  */
  33                 spin_lock(&journal->j_state_lock);
  34 +               spin_lock(&journal->j_list_lock);
  35                 nblocks = jbd_space_needed(journal);
  36                 if (__jbd2_log_space_left(journal) < nblocks) {
  37 +                       int chkpt = journal->j_checkpoint_transactions != NULL;
  38 +
  39 +                       spin_unlock(&journal->j_list_lock);
  40                         spin_unlock(&journal->j_state_lock);
  41 -                       jbd2_log_do_checkpoint(journal);
  42 +                       if (chkpt) {
  43 +                               jbd2_log_do_checkpoint(journal);
  44 +                       } else {
  45 +                               printk(KERN_ERR "%s: no transactions\n",
  46 +                                      __func__);
  47 +                               jbd2_journal_abort(journal, 0);
  48 +                       }
  49 +
  50                         spin_lock(&journal->j_state_lock);
  51 +               } else {
  52 +                       spin_unlock(&journal->j_list_lock);
  53                 }
  54                 mutex_unlock(&journal->j_checkpoint_mutex);
  55         }