From 6f890df0a7efe3181aceb5d8bcd4af7deb2abce5 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 21 Aug 2017 22:53:45 +0800 Subject: [PATCH] f2fs: fix out-of-order execution in f2fs_issue_flush In f2fs_issue_flush, due to out-of-order execution of CPU, wake_up can be called before we insert issue_list, result in long latency of wait_for_completion. Fix this by adding smp_mb() to force the order of related codes. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/segment.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index e3922f902c8c..be1c49b9402b 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -549,7 +549,10 @@ int f2fs_issue_flush(struct f2fs_sb_info *sbi) atomic_inc(&fcc->issing_flush); llist_add(&cmd.llnode, &fcc->issue_list); - if (!fcc->dispatch_list) + /* update issue_list before we wake up issue_flush thread */ + smp_mb(); + + if (waitqueue_active(&fcc->flush_wait_queue)) wake_up(&fcc->flush_wait_queue); if (fcc->f2fs_issue_flush) {