+static void blk_ioc_discard_endio(struct bio *bio, int err)
+{
+ if (err) {
+ if (err == -EOPNOTSUPP)
+ set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ }
+ complete(bio->bi_private);
+}
+
+static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
+ uint64_t len)
+{
+ struct request_queue *q = bdev_get_queue(bdev);
+ int ret = 0;
+
+ if (start & 511)
+ return -EINVAL;
+ if (len & 511)
+ return -EINVAL;
+ start >>= 9;
+ len >>= 9;
+
+ if (start + len > (bdev->bd_inode->i_size >> 9))
+ return -EINVAL;
+
+ if (!q->prepare_discard_fn)
+ return -EOPNOTSUPP;
+
+ while (len && !ret) {
+ DECLARE_COMPLETION_ONSTACK(wait);
+ struct bio *bio;
+
+ bio = bio_alloc(GFP_KERNEL, 0);
+ if (!bio)
+ return -ENOMEM;
+
+ bio->bi_end_io = blk_ioc_discard_endio;
+ bio->bi_bdev = bdev;
+ bio->bi_private = &wait;
+ bio->bi_sector = start;
+
+ if (len > q->max_hw_sectors) {
+ bio->bi_size = q->max_hw_sectors << 9;
+ len -= q->max_hw_sectors;
+ start += q->max_hw_sectors;
+ } else {
+ bio->bi_size = len << 9;
+ len = 0;
+ }
+ submit_bio(DISCARD_NOBARRIER, bio);
+
+ wait_for_completion(&wait);
+
+ if (bio_flagged(bio, BIO_EOPNOTSUPP))
+ ret = -EOPNOTSUPP;
+ else if (!bio_flagged(bio, BIO_UPTODATE))
+ ret = -EIO;
+ bio_put(bio);
+ }
+ return ret;
+}
+