Commit ff4b5eb8 authored Aug 21, 2017 by Chao Yu Committed by Sahitya Tummala Dec 16, 2017

f2fs: fix out-of-order execution in f2fs_issue_flush



commit 6f890df0a7efe3181aceb5d8bcd4af7deb2abce5 upstream.

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 <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Git-commit: 6ed7ad60
Git-repo: https://android.googlesource.com/kernel/common.git


Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>

parent 2204c737

fs/f2fs/segment.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -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) {