> On Mar 30, 2021, at 6:59 PM, kernel test robot <lkp@xxxxxxxxx> wrote: > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > head: 4143e05b7b171902f4938614c2a68821e1af46bc > commit: 254c271da0712ea8914f187588e0f81f7678ee2f [6117/8451] md/raid10: improve discard request for far layout > compiler: aarch64-linux-gcc (GCC) 9.3.0 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > cppcheck warnings: (new ones prefixed by >>) > In file included from drivers/md/raid10.c: >>> drivers/md/raid10.c:1707:39: warning: Uninitialized variable: first_r10bio [uninitvar] > r10_bio->master_bio = (struct bio *)first_r10bio; > ^ > > vim +1707 drivers/md/raid10.c > > 1573 > 1574 /* > 1575 * There are some limitations to handle discard bio > 1576 * 1st, the discard size is bigger than stripe_size*2. > 1577 * 2st, if the discard bio spans reshape progress, we use the old way to > 1578 * handle discard bio > 1579 */ > 1580 static int raid10_handle_discard(struct mddev *mddev, struct bio *bio) > 1581 { > 1582 struct r10conf *conf = mddev->private; > 1583 struct geom *geo = &conf->geo; > 1584 int far_copies = geo->far_copies; > 1585 bool first_copy = true; > 1586 struct r10bio *r10_bio, *first_r10bio; > 1587 struct bio *split; > 1588 int disk; > 1589 sector_t chunk; > 1590 unsigned int stripe_size; > 1591 unsigned int stripe_data_disks; > 1592 sector_t split_size; > 1593 sector_t bio_start, bio_end; > 1594 sector_t first_stripe_index, last_stripe_index; > 1595 sector_t start_disk_offset; > 1596 unsigned int start_disk_index; > 1597 sector_t end_disk_offset; > 1598 unsigned int end_disk_index; > 1599 unsigned int remainder; > 1600 > 1601 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) > 1602 return -EAGAIN; > 1603 > 1604 wait_barrier(conf); > 1605 > 1606 /* > 1607 * Check reshape again to avoid reshape happens after checking > 1608 * MD_RECOVERY_RESHAPE and before wait_barrier > 1609 */ > 1610 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) > 1611 goto out; > 1612 > 1613 if (geo->near_copies) > 1614 stripe_data_disks = geo->raid_disks / geo->near_copies + > 1615 geo->raid_disks % geo->near_copies; > 1616 else > 1617 stripe_data_disks = geo->raid_disks; > 1618 > 1619 stripe_size = stripe_data_disks << geo->chunk_shift; > 1620 > 1621 bio_start = bio->bi_iter.bi_sector; > 1622 bio_end = bio_end_sector(bio); > 1623 > 1624 /* > 1625 * Maybe one discard bio is smaller than strip size or across one > 1626 * stripe and discard region is larger than one stripe size. For far > 1627 * offset layout, if the discard region is not aligned with stripe > 1628 * size, there is hole when we submit discard bio to member disk. > 1629 * For simplicity, we only handle discard bio which discard region > 1630 * is bigger than stripe_size * 2 > 1631 */ > 1632 if (bio_sectors(bio) < stripe_size*2) > 1633 goto out; > 1634 > 1635 /* > 1636 * Keep bio aligned with strip size. > 1637 */ > 1638 div_u64_rem(bio_start, stripe_size, &remainder); > 1639 if (remainder) { > 1640 split_size = stripe_size - remainder; > 1641 split = bio_split(bio, split_size, GFP_NOIO, &conf->bio_split); > 1642 bio_chain(split, bio); > 1643 allow_barrier(conf); > 1644 /* Resend the fist split part */ > 1645 submit_bio_noacct(split); > 1646 wait_barrier(conf); > 1647 } > 1648 div_u64_rem(bio_end, stripe_size, &remainder); > 1649 if (remainder) { > 1650 split_size = bio_sectors(bio) - remainder; > 1651 split = bio_split(bio, split_size, GFP_NOIO, &conf->bio_split); > 1652 bio_chain(split, bio); > 1653 allow_barrier(conf); > 1654 /* Resend the second split part */ > 1655 submit_bio_noacct(bio); > 1656 bio = split; > 1657 wait_barrier(conf); > 1658 } > 1659 > 1660 bio_start = bio->bi_iter.bi_sector; > 1661 bio_end = bio_end_sector(bio); > 1662 > 1663 /* > 1664 * Raid10 uses chunk as the unit to store data. It's similar like raid0. > 1665 * One stripe contains the chunks from all member disk (one chunk from > 1666 * one disk at the same HBA address). For layout detail, see 'man md 4' > 1667 */ > 1668 chunk = bio_start >> geo->chunk_shift; > 1669 chunk *= geo->near_copies; > 1670 first_stripe_index = chunk; > 1671 start_disk_index = sector_div(first_stripe_index, geo->raid_disks); > 1672 if (geo->far_offset) > 1673 first_stripe_index *= geo->far_copies; > 1674 start_disk_offset = (bio_start & geo->chunk_mask) + > 1675 (first_stripe_index << geo->chunk_shift); > 1676 > 1677 chunk = bio_end >> geo->chunk_shift; > 1678 chunk *= geo->near_copies; > 1679 last_stripe_index = chunk; > 1680 end_disk_index = sector_div(last_stripe_index, geo->raid_disks); > 1681 if (geo->far_offset) > 1682 last_stripe_index *= geo->far_copies; > 1683 end_disk_offset = (bio_end & geo->chunk_mask) + > 1684 (last_stripe_index << geo->chunk_shift); > 1685 > 1686 retry_discard: > 1687 r10_bio = mempool_alloc(&conf->r10bio_pool, GFP_NOIO); > 1688 r10_bio->mddev = mddev; > 1689 r10_bio->state = 0; > 1690 r10_bio->sectors = 0; > 1691 memset(r10_bio->devs, 0, sizeof(r10_bio->devs[0]) * geo->raid_disks); > 1692 wait_blocked_dev(mddev, r10_bio); > 1693 > 1694 /* > 1695 * For far layout it needs more than one r10bio to cover all regions. > 1696 * Inspired by raid10_sync_request, we can use the first r10bio->master_bio > 1697 * to record the discard bio. Other r10bio->master_bio record the first > 1698 * r10bio. The first r10bio only release after all other r10bios finish. > 1699 * The discard bio returns only first r10bio finishes > 1700 */ > 1701 if (first_copy) { > 1702 r10_bio->master_bio = bio; > 1703 set_bit(R10BIO_Discard, &r10_bio->state); > 1704 first_copy = false; > 1705 first_r10bio = r10_bio; > 1706 } else >> 1707 r10_bio->master_bio = (struct bio *)first_r10bio; This is a false alert. The function starts with first_copy = true. When we hit else clause, first_r10bio is already initialized. Thanks, Song [...]
