md/raid5: use bdev_write_cache instead of open coding it

Use the bdev_write_cache instead of two equivalent open coded checks.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NSong Liu <song@kernel.org>

drivers/md/raid5-cache.c

@@ -3062,7 +3062,6 @@ void r5c_update_on_rdev_error(struct mddev *mddev, struct md_rdev *rdev)
 
 int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
 {
-	struct request_queue *q = bdev_get_queue(rdev->bdev);
 	struct r5l_log *log;
 	int ret;
 
@@ -3091,9 +3090,7 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
 	if (!log)
 		return -ENOMEM;
 	log->rdev = rdev;
-
-	log->need_cache_flush = test_bit(QUEUE_FLAG_WC, &q->queue_flags) != 0;
-
+	log->need_cache_flush = bdev_write_cache(rdev->bdev);
 	log->uuid_checksum = crc32c_le(~0, rdev->mddev->uuid,
 				       sizeof(rdev->mddev->uuid));
 

drivers/md/raid5-ppl.c

@@ -1301,8 +1301,6 @@ static int ppl_validate_rdev(struct md_rdev *rdev)
 
 static void ppl_init_child_log(struct ppl_log *log, struct md_rdev *rdev)
 {
-	struct request_queue *q;
-
 	if ((rdev->ppl.size << 9) >= (PPL_SPACE_SIZE +
 				      PPL_HEADER_SIZE) * 2) {
 		log->use_multippl = true;
@@ -1316,8 +1314,7 @@ static void ppl_init_child_log(struct ppl_log *log, struct md_rdev *rdev)
 	}
 	log->next_io_sector = rdev->ppl.sector;
 
-	q = bdev_get_queue(rdev->bdev);
-	if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
+	if (bdev_write_cache(rdev->bdev))
 		log->wb_cache_on = true;
 }