jbd2: if the journal is aborted then don't allow update of the log tail

BugLink: http://bugs.launchpad.net/bugs/1768429

commit 85e0c4e8 upstream.

This updates the jbd2 superblock unnecessarily, and on an abort we
shouldn't truncate the log.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

fs/jbd2/journal.c

@@ -914,7 +914,7 @@ int __jbd2_update_log_tail(journal_t *journal, tid_t tid, unsigned long block)
 }
 
 /*
- * This is a variaon of __jbd2_update_log_tail which checks for validity of
+ * This is a variation of __jbd2_update_log_tail which checks for validity of
  * provided log tail and locks j_checkpoint_mutex. So it is safe against races
  * with other threads updating log tail.
  */
@@ -1384,6 +1384,9 @@ int jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
 	journal_superblock_t *sb = journal->j_superblock;
 	int ret;
 
+	if (is_journal_aborted(journal))
+		return -EIO;
+
 	BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
 	jbd_debug(1, "JBD2: updating superblock (start %lu, seq %u)\n",
 		  tail_block, tail_tid);