3 files changed, 28 insertions, 2 deletions

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 6479f15a5..ea14803 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -507,6 +507,24 @@ void r5l_write_stripe_run(struct r5l_log *log)
 	mutex_unlock(&log->io_mutex);
 }
 
+int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio)
+{
+	if (!log)
+		return -ENODEV;
+	/*
+	 * we flush log disk cache first, then write stripe data to raid disks.
+	 * So if bio is finished, the log disk cache is flushed already. The
+	 * recovery guarantees we can recovery the bio from log disk, so we
+	 * don't need to flush again
+	 */
+	if (bio->bi_iter.bi_size == 0) {
+		bio_endio(bio);
+		return 0;
+	}
+	bio->bi_rw &= ~REQ_FLUSH;
+	return -EAGAIN;
+}
+
 /* This will run after log space is reclaimed */
 static void r5l_run_no_space_stripes(struct r5l_log *log)
 {
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 46042c7..a622ccb 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5146,8 +5146,15 @@ static void make_request(struct mddev *mddev, struct bio * bi)
 	bool do_prepare;
 
 	if (unlikely(bi->bi_rw & REQ_FLUSH)) {
-		md_flush_request(mddev, bi);
-		return;
+		int ret = r5l_handle_flush_request(conf->log, bi);
+
+		if (ret == 0)
+			return;
+		if (ret == -ENODEV) {
+			md_flush_request(mddev, bi);
+			return;
+		}
+		/* ret == -EAGAIN, fallback */
 	}
 
 	md_write_start(mddev, bi);
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 1f16d43..32c8ce8 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -629,4 +629,5 @@ extern int r5l_write_stripe(struct r5l_log *log, struct stripe_head *head_sh);
 extern void r5l_write_stripe_run(struct r5l_log *log);
 extern void r5l_flush_stripe_to_raid(struct r5l_log *log);
 extern void r5l_stripe_write_finished(struct stripe_head *sh);
+extern int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio);
 #endif