On Tue, Jan 26, 2021 at 7:19 AM Christoph Hellwig <hch@xxxxxx> wrote:
>
> Refactor raid5_read_one_chunk so that all simple checks are done
> before allocating the bio.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Song Liu <song@xxxxxxxxxx>
Thanks for the clean-up!
> ---
> drivers/md/raid5.c | 108 +++++++++++++++++++--------------------------
> 1 file changed, 45 insertions(+), 63 deletions(-)
>
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index f411b9e5c332f4..a348b2adf2a9f9 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -5393,90 +5393,72 @@ static void raid5_align_endio(struct bio *bi)
> static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
> {
> struct r5conf *conf = mddev->private;
> - int dd_idx;
> - struct bio* align_bi;
> + struct bio *align_bio;
> struct md_rdev *rdev;
> - sector_t end_sector;
> + sector_t sector, end_sector, first_bad;
> + int bad_sectors, dd_idx;
>
> if (!in_chunk_boundary(mddev, raid_bio)) {
> pr_debug("%s: non aligned\n", __func__);
> return 0;
> }
> - /*
> - * use bio_clone_fast to make a copy of the bio
> - */
> - align_bi = bio_clone_fast(raid_bio, GFP_NOIO, &mddev->bio_set);
> - if (!align_bi)
> - return 0;
> - /*
> - * set bi_end_io to a new function, and set bi_private to the
> - * original bio.
> - */
> - align_bi->bi_end_io = raid5_align_endio;
> - align_bi->bi_private = raid_bio;
> - /*
> - * compute position
> - */
> - align_bi->bi_iter.bi_sector =
> - raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
> - 0, &dd_idx, NULL);
>
> - end_sector = bio_end_sector(align_bi);
> + sector = raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector, 0,
> + &dd_idx, NULL);
> + end_sector = bio_end_sector(raid_bio);
> +
> rcu_read_lock();
> + if (r5c_big_stripe_cached(conf, sector))
> + goto out_rcu_unlock;
> +
> rdev = rcu_dereference(conf->disks[dd_idx].replacement);
> if (!rdev || test_bit(Faulty, &rdev->flags) ||
> rdev->recovery_offset < end_sector) {
> rdev = rcu_dereference(conf->disks[dd_idx].rdev);
> - if (rdev &&
> - (test_bit(Faulty, &rdev->flags) ||
> + if (!rdev)
> + goto out_rcu_unlock;
> + if (test_bit(Faulty, &rdev->flags) ||
> !(test_bit(In_sync, &rdev->flags) ||
> - rdev->recovery_offset >= end_sector)))
> - rdev = NULL;
> + rdev->recovery_offset >= end_sector))
> + goto out_rcu_unlock;
> }
>
> - if (r5c_big_stripe_cached(conf, align_bi->bi_iter.bi_sector)) {
> - rcu_read_unlock();
> - bio_put(align_bi);
> + atomic_inc(&rdev->nr_pending);
> + rcu_read_unlock();
> +
> + align_bio = bio_clone_fast(raid_bio, GFP_NOIO, &mddev->bio_set);
> + bio_set_dev(align_bio, rdev->bdev);
> + align_bio->bi_end_io = raid5_align_endio;
> + align_bio->bi_private = raid_bio;
> + align_bio->bi_iter.bi_sector = sector;
> +
> + raid_bio->bi_next = (void *)rdev;
> +
> + if (is_badblock(rdev, sector, bio_sectors(align_bio), &first_bad,
> + &bad_sectors)) {
> + bio_put(align_bio);
> + rdev_dec_pending(rdev, mddev);
> return 0;
> }
>
> - if (rdev) {
> - sector_t first_bad;
> - int bad_sectors;
> -
> - atomic_inc(&rdev->nr_pending);
> - rcu_read_unlock();
> - raid_bio->bi_next = (void*)rdev;
> - bio_set_dev(align_bi, rdev->bdev);
> -
> - if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
> - bio_sectors(align_bi),
> - &first_bad, &bad_sectors)) {
> - bio_put(align_bi);
> - rdev_dec_pending(rdev, mddev);
> - return 0;
> - }
> + /* No reshape active, so we can trust rdev->data_offset */
> + align_bio->bi_iter.bi_sector += rdev->data_offset;
>
> - /* No reshape active, so we can trust rdev->data_offset */
> - align_bi->bi_iter.bi_sector += rdev->data_offset;
> + spin_lock_irq(&conf->device_lock);
> + wait_event_lock_irq(conf->wait_for_quiescent, conf->quiesce == 0,
> + conf->device_lock);
> + atomic_inc(&conf->active_aligned_reads);
> + spin_unlock_irq(&conf->device_lock);
>
> - spin_lock_irq(&conf->device_lock);
> - wait_event_lock_irq(conf->wait_for_quiescent,
> - conf->quiesce == 0,
> - conf->device_lock);
> - atomic_inc(&conf->active_aligned_reads);
> - spin_unlock_irq(&conf->device_lock);
> + if (mddev->gendisk)
> + trace_block_bio_remap(align_bio, disk_devt(mddev->gendisk),
> + raid_bio->bi_iter.bi_sector);
> + submit_bio_noacct(align_bio);
> + return 1;
>
> - if (mddev->gendisk)
> - trace_block_bio_remap(align_bi, disk_devt(mddev->gendisk),
> - raid_bio->bi_iter.bi_sector);
> - submit_bio_noacct(align_bi);
> - return 1;
> - } else {
> - rcu_read_unlock();
> - bio_put(align_bi);
> - return 0;
> - }
> +out_rcu_unlock:
> + rcu_read_unlock();
> + return 0;
> }
>
> static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
> --
> 2.29.2
>
