* could wait for this and below md_handle_request could wait for those
         * bios because of suspend check
         */
-       mddev->last_flush = mddev->start_flush;
+       mddev->prev_flush_start = mddev->start_flush;
        mddev->flush_bio = NULL;
        wake_up(&mddev->sb_wait);
 
  */
 bool md_flush_request(struct mddev *mddev, struct bio *bio)
 {
-       ktime_t start = ktime_get_boottime();
+       ktime_t req_start = ktime_get_boottime();
        spin_lock_irq(&mddev->lock);
        wait_event_lock_irq(mddev->sb_wait,
                            !mddev->flush_bio ||
-                           ktime_after(mddev->last_flush, start),
+                           ktime_after(mddev->prev_flush_start, req_start),
                            mddev->lock);
-       if (!ktime_after(mddev->last_flush, start)) {
+       if (!ktime_after(mddev->prev_flush_start, req_start)) {
                WARN_ON(mddev->flush_bio);
                mddev->flush_bio = bio;
                bio = NULL;
 
         */
        struct bio *flush_bio;
        atomic_t flush_pending;
-       ktime_t start_flush, last_flush; /* last_flush is when the last completed
-                                         * flush was started.
-                                         */
+       ktime_t start_flush, prev_flush_start; /* prev_flush_start is when the previous completed
+                                               * flush was started.
+                                               */
        struct work_struct flush_work;
        struct work_struct event_work;  /* used by dm to report failure event */
        mempool_t *serial_info_pool;