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Commit a78bb11d authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
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jbd2: protect all log tail updates with j_checkpoint_mutex 



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 jbd2_journal_commit_transaction() and jbd2_journal_flush() can
really race with other log tail updates (e.g. someone doing
jbd2_journal_flush() with someone running jbd2_cleanup_journal_tail()). So
protect all log tail updates with j_checkpoint_mutex.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 24bcc89c

fs/jbd2/commit.c

+2 −0
Original line number Diff line number Diff line
@@ -340,7 +340,9 @@ void jbd2_journal_commit_transaction(journal_t *journal) 
	/* Do we need to erase the effects of a prior jbd2_journal_flush? */

	if (journal->j_flags & JBD2_FLUSHED) {

		jbd_debug(3, "super block updated\n");

		mutex_lock(&journal->j_checkpoint_mutex);

		jbd2_journal_update_sb_log_tail(journal);

		mutex_unlock(&journal->j_checkpoint_mutex);

	} else {

		jbd_debug(3, "superblock not updated\n");

	}

fs/jbd2/journal.c

+16 −3
Original line number Diff line number Diff line
@@ -1123,8 +1123,11 @@ static int journal_reset(journal_t *journal) 
			journal->j_errno);

		journal->j_flags |= JBD2_FLUSHED;

	} else {

		/* Lock here to make assertions happy... */

		mutex_lock(&journal->j_checkpoint_mutex);

		/* Add the dynamic fields and write it to disk. */

		jbd2_journal_update_sb_log_tail(journal);

		mutex_unlock(&journal->j_checkpoint_mutex);

	}

	return jbd2_journal_start_thread(journal);

}
@@ -1173,6 +1176,7 @@ void jbd2_journal_update_sb_log_tail(journal_t *journal) 
{

	journal_superblock_t *sb = journal->j_superblock;



	BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));

	read_lock(&journal->j_state_lock);

	jbd_debug(1, "JBD2: updating superblock (start %ld, seq %d)\n",

		  journal->j_tail, journal->j_tail_sequence);
@@ -1201,6 +1205,7 @@ static void jbd2_mark_journal_empty(journal_t *journal) 
{

	journal_superblock_t *sb = journal->j_superblock;



	BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));

	read_lock(&journal->j_state_lock);

	jbd_debug(1, "JBD2: Marking journal as empty (seq %d)\n",

		  journal->j_tail_sequence);
@@ -1434,9 +1439,11 @@ int jbd2_journal_destroy(journal_t *journal) 
	spin_unlock(&journal->j_list_lock);



	if (journal->j_sb_buffer) {

		if (!is_journal_aborted(journal))

		if (!is_journal_aborted(journal)) {

			mutex_lock(&journal->j_checkpoint_mutex);

			jbd2_mark_journal_empty(journal);

		else

			mutex_unlock(&journal->j_checkpoint_mutex);

		} else

			err = -EIO;

		brelse(journal->j_sb_buffer);

	}
@@ -1630,6 +1637,7 @@ int jbd2_journal_flush(journal_t *journal) 
	if (is_journal_aborted(journal))

		return -EIO;



	mutex_lock(&journal->j_checkpoint_mutex);

	jbd2_cleanup_journal_tail(journal);



	/* Finally, mark the journal as really needing no recovery.
@@ -1638,6 +1646,7 @@ int jbd2_journal_flush(journal_t *journal) 
	 * commits of data to the journal will restore the current

	 * s_start value. */

	jbd2_mark_journal_empty(journal);

	mutex_unlock(&journal->j_checkpoint_mutex);

	write_lock(&journal->j_state_lock);

	J_ASSERT(!journal->j_running_transaction);

	J_ASSERT(!journal->j_committing_transaction);
@@ -1678,8 +1687,12 @@ int jbd2_journal_wipe(journal_t *journal, int write) 
		write ? "Clearing" : "Ignoring");



	err = jbd2_journal_skip_recovery(journal);

	if (write)

	if (write) {

		/* Lock to make assertions happy... */

		mutex_lock(&journal->j_checkpoint_mutex);

		jbd2_mark_journal_empty(journal);

		mutex_unlock(&journal->j_checkpoint_mutex);

	}



 no_recovery:

	return err;