1 files changed, 15 insertions, 0 deletions

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index ca0f5eb62b20..886849370950 100644
--- a/fs/jbd2/checkpoint.c
+++ b/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)
         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;