[PATCH] md/raid5: let stripe batch bm_seq comparison wrap-safe

[Chen Cheng]

From: Chen Cheng <chencheng@xxxxxxxxx>

Once the 32-bit seq wraps, a newer bm_seq can look smaller
than old, so .. covert to wrap-safe calculate way.

Signed-off-by: Chen Cheng <chencheng@xxxxxxxxx>
---
 drivers/md/raid5.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 6d01c35b5499..a08230aac711 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -997,11 +997,11 @@ static void stripe_add_to_batch_list(struct r5conf *conf,
 			md_wakeup_thread(conf->mddev->thread);
 
 	if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
 		int seq = sh->bm_seq;
 		if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
-		    sh->batch_head->bm_seq > seq)
+		    sh->batch_head->bm_seq - seq > 0)
 			seq = sh->batch_head->bm_seq;
 		set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
 		sh->batch_head->bm_seq = seq;
 	}
 
-- 
2.54.0