jbd: protect all log tail updates with j_checkpoint_mutex
Jan Kara [Sat, 7 Apr 2012 10:50:13 +0000 (12:50 +0200)]
There are some log tail updates that are not protected by j_checkpoint_mutex.
Some of these are harmless because they happen during startup or shutdown but
updates in journal_commit_transaction() and journal_flush() can really race
with other log tail updates (e.g. someone doing journal_flush() with someone
running cleanup_journal_tail()). So protect all log tail updates with
j_checkpoint_mutex.

Signed-off-by: Jan Kara <jack@suse.cz>

fs/jbd/commit.c
fs/jbd/journal.c

index dba9cfd..1b27f46 100644 (file)
@@ -308,7 +308,9 @@ void journal_commit_transaction(journal_t *journal)
        /* Do we need to erase the effects of a prior journal_flush? */
        if (journal->j_flags & JFS_FLUSHED) {
                jbd_debug(3, "super block updated\n");
+               mutex_lock(&journal->j_checkpoint_mutex);
                journal_update_sb_log_tail(journal);
+               mutex_unlock(&journal->j_checkpoint_mutex);
        } else {
                jbd_debug(3, "superblock not updated\n");
        }
index 44c104a..b29c767 100644 (file)
@@ -936,8 +936,11 @@ static int journal_reset(journal_t *journal)
                        journal->j_errno);
                journal->j_flags |= JFS_FLUSHED;
        } else {
+               /* Lock here to make assertions happy... */
+               mutex_lock(&journal->j_checkpoint_mutex);
                /* Add the dynamic fields and write it to disk. */
                journal_update_sb_log_tail(journal);
+               mutex_unlock(&journal->j_checkpoint_mutex);
        }
        return journal_start_thread(journal);
 }
@@ -1061,6 +1064,7 @@ void journal_update_sb_log_tail(journal_t *journal)
 {
        journal_superblock_t *sb = journal->j_superblock;
 
+       BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
        spin_lock(&journal->j_state_lock);
        jbd_debug(1,"JBD: updating superblock (start %u, seq %d, errno %d)\n",
                  journal->j_tail, journal->j_tail_sequence, journal->j_errno);
@@ -1089,6 +1093,7 @@ static void mark_journal_empty(journal_t *journal)
 {
        journal_superblock_t *sb = journal->j_superblock;
 
+       BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
        spin_lock(&journal->j_state_lock);
        jbd_debug(1, "JBD: Marking journal as empty (seq %d)\n",
                  journal->j_tail_sequence);
@@ -1293,6 +1298,8 @@ int journal_destroy(journal_t *journal)
 
        /* Force any old transactions to disk */
 
+       /* We cannot race with anybody but must keep assertions happy */
+       mutex_lock(&journal->j_checkpoint_mutex);
        /* Totally anal locking here... */
        spin_lock(&journal->j_list_lock);
        while (journal->j_checkpoint_transactions != NULL) {
@@ -1315,6 +1322,7 @@ int journal_destroy(journal_t *journal)
                        err = -EIO;
                brelse(journal->j_sb_buffer);
        }
+       mutex_unlock(&journal->j_checkpoint_mutex);
 
        if (journal->j_inode)
                iput(journal->j_inode);
@@ -1528,6 +1536,7 @@ int journal_flush(journal_t *journal)
        if (is_journal_aborted(journal))
                return -EIO;
 
+       mutex_lock(&journal->j_checkpoint_mutex);
        cleanup_journal_tail(journal);
 
        /* Finally, mark the journal as really needing no recovery.
@@ -1536,6 +1545,7 @@ int journal_flush(journal_t *journal)
         * commits of data to the journal will restore the current
         * s_start value. */
        mark_journal_empty(journal);
+       mutex_unlock(&journal->j_checkpoint_mutex);
        spin_lock(&journal->j_state_lock);
        J_ASSERT(!journal->j_running_transaction);
        J_ASSERT(!journal->j_committing_transaction);
@@ -1576,8 +1586,12 @@ int journal_wipe(journal_t *journal, int write)
                write ? "Clearing" : "Ignoring");
 
        err = journal_skip_recovery(journal);
-       if (write)
+       if (write) {
+               /* Lock to make assertions happy... */
+               mutex_lock(&journal->j_checkpoint_mutex);
                mark_journal_empty(journal);
+               mutex_unlock(&journal->j_checkpoint_mutex);
+       }
 
  no_recovery:
        return err;