[PATCH] btrfs: fix CHECK_INTEGRITY warning when !QUEUE_FLAG_WC

[wangyugui <wangyugui@e16-tech.com>]

xfstest/btrfs/220 tigger a check-integrity warning when
1) CONFIG_BTRFS_FS_CHECK_INTEGRITY=y
2) xfstest/btrfs/220 run on a disk with WCE=1

In write_dev_flush(), submit_bio(REQ_SYNC | REQ_PREFLUSH) can be skipped when
!QUEUE_FLAG_WC. but btrfsic_submit_bio() != submit_bio() when CONFIG_BTRFS_FS_CHECK_INTEGRITY

Signed-off-by: wangyugui <wangyugui@e16-tech.com>
---
 fs/btrfs/disk-io.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 355ea88..7b17357 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3971,8 +3971,14 @@ static void write_dev_flush(struct btrfs_device *device)
 	struct request_queue *q = bdev_get_queue(device->bdev);
 	struct bio *bio = device->flush_bio;
 
+	#ifndef CONFIG_BTRFS_FS_CHECK_INTEGRITY
+	/*
+	* submit_bio(REQ_SYNC | REQ_PREFLUSH) can be skipped when !QUEUE_FLAG_WC.
+	* but btrfsic_submit_bio() != submit_bio() when CONFIG_BTRFS_FS_CHECK_INTEGRITY
+	*/
 	if (!test_bit(QUEUE_FLAG_WC, &q->queue_flags))
 		return;
+	#endif
 
 	bio_reset(bio);
 	bio->bi_end_io = btrfs_end_empty_barrier;
-- 
2.32.0