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: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 19371a8..6705717 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -340,7 +340,9 @@
/* 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");
}