--- fs/jbd2/checkpoint.c

+++ fs/jbd2/checkpoint.c

@@ -22,6 +22,7 @@

#include <linux/jbd2.h>

#include <linux/errno.h>

#include <linux/slab.h>

+#include <linux/blkdev.h>

#include <trace/events/jbd2.h>

/*

@@ -515,6 +516,20 @@ int jbd2_cleanup_journal_tail(journal_t

journal->j_tail_sequence = first_tid;

journal->j_tail = blocknr;

spin_unlock(&journal->j_state_lock);

+

+ /*

+ * If there is an external journal, we need to make sure that

+ * any data blocks that were recently written out --- perhaps

+ * by jbd2_log_do_checkpoint() --- are flushed out before we

+ * drop the transactions from the external journal. It's

+ * unlikely this will be necessary, especially with a

+ * appropriately sized journal, but we need this to guarantee

+ * correctness. Fortunately jbd2_cleanup_journal_tail()

+ * doesn't get called all that often.

+ */

+ if ((journal->j_fs_dev != journal->j_dev) &&

+ (journal->j_flags & JBD2_BARRIER))

+ blkdev_issue_flush(journal->j_fs_dev, NULL);

if (!(journal->j_flags & JBD2_ABORT))

jbd2_journal_update_superblock(journal, 1);

return 0;