Merge branch 'sh/stable-updates' into sh-latest

1 files changed, 10 insertions, 1 deletions

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 211930246f20..41d5b8f2bf92 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -1372,8 +1372,17 @@ xlog_sync(xlog_t		*log,
         XFS_BUF_ASYNC(bp);
         bp->b_flags |= XBF_LOG_BUFFER;
 
-        if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)
+        if (log->l_mp->m_flags & XFS_MOUNT_BARRIER) {
+                /*
+                 * If we have an external log device, flush the data device
+                 * before flushing the log to make sure all meta data
+                 * written back from the AIL actually made it to disk
+                 * before writing out the new log tail LSN in the log buffer.
+                 */
+                if (log->l_mp->m_logdev_targp != log->l_mp->m_ddev_targp)
+                        xfs_blkdev_issue_flush(log->l_mp->m_ddev_targp);
                 XFS_BUF_ORDERED(bp);
+        }
 
         ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
         ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);