+static int check_and_add_wb(struct md_rdev *rdev, sector_t lo, sector_t hi)
+{
+ struct wb_info *wi, *temp_wi;
+ unsigned long flags;
+ int ret = 0;
+ struct mddev *mddev = rdev->mddev;
+
+ wi = mempool_alloc(mddev->wb_info_pool, GFP_NOIO);
+
+ spin_lock_irqsave(&rdev->wb_list_lock, flags);
+ list_for_each_entry(temp_wi, &rdev->wb_list, list) {
+ /* collision happened */
+ if (hi > temp_wi->lo && lo < temp_wi->hi) {
+ ret = -EBUSY;
+ break;
+ }
+ }
+
+ if (!ret) {
+ wi->lo = lo;
+ wi->hi = hi;
+ list_add(&wi->list, &rdev->wb_list);
+ } else
+ mempool_free(wi, mddev->wb_info_pool);
+ spin_unlock_irqrestore(&rdev->wb_list_lock, flags);
+
+ return ret;
+}
+
+static void remove_wb(struct md_rdev *rdev, sector_t lo, sector_t hi)
+{
+ struct wb_info *wi;
+ unsigned long flags;
+ int found = 0;
+ struct mddev *mddev = rdev->mddev;
+
+ spin_lock_irqsave(&rdev->wb_list_lock, flags);
+ list_for_each_entry(wi, &rdev->wb_list, list)
+ if (hi == wi->hi && lo == wi->lo) {
+ list_del(&wi->list);
+ mempool_free(wi, mddev->wb_info_pool);
+ found = 1;
+ break;
+ }
+
+ if (!found)
+ WARN_ON("The write behind IO is not recorded\n");
+ spin_unlock_irqrestore(&rdev->wb_list_lock, flags);
+ wake_up(&rdev->wb_io_wait);
+}
+