Re: [PATCH 04/23] md/md-bitmap: support discard for bitmap ops

[Xiao Ni <xni@redhat.com>]

On Sat, May 24, 2025 at 2:19 PM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@huawei.com>
>
> Use two new methods {start, end}_discard to handle discard IO, prepare
> to support new md bitmap.
>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
>  drivers/md/md-bitmap.c |  3 +++
>  drivers/md/md-bitmap.h | 12 ++++++++----
>  drivers/md/md.c        | 15 +++++++++++----
>  drivers/md/md.h        |  1 +
>  4 files changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> index 2997e09d463d..848626049dea 100644
> --- a/drivers/md/md-bitmap.c
> +++ b/drivers/md/md-bitmap.c
> @@ -2991,6 +2991,9 @@ static struct bitmap_operations bitmap_ops = {
>
>         .start_write            = bitmap_start_write,
>         .end_write              = bitmap_end_write,
> +       .start_discard          = bitmap_start_write,
> +       .end_discard            = bitmap_end_write,
> +
>         .start_sync             = bitmap_start_sync,
>         .end_sync               = bitmap_end_sync,
>         .cond_end_sync          = bitmap_cond_end_sync,
> diff --git a/drivers/md/md-bitmap.h b/drivers/md/md-bitmap.h
> index 9474e0d86fc6..4d804c07dbdd 100644
> --- a/drivers/md/md-bitmap.h
> +++ b/drivers/md/md-bitmap.h
> @@ -70,6 +70,9 @@ struct md_bitmap_stats {
>         struct file     *file;
>  };
>
> +typedef void (md_bitmap_fn)(struct mddev *mddev, sector_t offset,
> +                           unsigned long sectors);
> +
>  struct bitmap_operations {
>         struct md_submodule_head head;
>
> @@ -90,10 +93,11 @@ struct bitmap_operations {
>         void (*end_behind_write)(struct mddev *mddev);
>         void (*wait_behind_writes)(struct mddev *mddev);
>
> -       void (*start_write)(struct mddev *mddev, sector_t offset,
> -                           unsigned long sectors);
> -       void (*end_write)(struct mddev *mddev, sector_t offset,
> -                         unsigned long sectors);
> +       md_bitmap_fn *start_write;
> +       md_bitmap_fn *end_write;
> +       md_bitmap_fn *start_discard;
> +       md_bitmap_fn *end_discard;
> +
>         bool (*start_sync)(struct mddev *mddev, sector_t offset,
>                            sector_t *blocks, bool degraded);
>         void (*end_sync)(struct mddev *mddev, sector_t offset, sector_t *blocks);
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 04a659f40cd6..466087cef4f9 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -8845,18 +8845,24 @@ EXPORT_SYMBOL_GPL(md_submit_discard_bio);
>  static void md_bitmap_start(struct mddev *mddev,
>                             struct md_io_clone *md_io_clone)
>  {
> +       md_bitmap_fn *fn = unlikely(md_io_clone->rw == STAT_DISCARD) ?
> +                          mddev->bitmap_ops->start_discard :
> +                          mddev->bitmap_ops->start_write;
> +
>         if (mddev->pers->bitmap_sector)
>                 mddev->pers->bitmap_sector(mddev, &md_io_clone->offset,
>                                            &md_io_clone->sectors);
>
> -       mddev->bitmap_ops->start_write(mddev, md_io_clone->offset,
> -                                      md_io_clone->sectors);
> +       fn(mddev, md_io_clone->offset, md_io_clone->sectors);
>  }
>
>  static void md_bitmap_end(struct mddev *mddev, struct md_io_clone *md_io_clone)
>  {
> -       mddev->bitmap_ops->end_write(mddev, md_io_clone->offset,
> -                                    md_io_clone->sectors);
> +       md_bitmap_fn *fn = unlikely(md_io_clone->rw == STAT_DISCARD) ?
> +                          mddev->bitmap_ops->end_discard :
> +                          mddev->bitmap_ops->end_write;
> +
> +       fn(mddev, md_io_clone->offset, md_io_clone->sectors);
>  }
>
>  static void md_end_clone_io(struct bio *bio)
> @@ -8895,6 +8901,7 @@ static void md_clone_bio(struct mddev *mddev, struct bio **bio)
>         if (bio_data_dir(*bio) == WRITE && md_bitmap_enabled(mddev)) {
>                 md_io_clone->offset = (*bio)->bi_iter.bi_sector;
>                 md_io_clone->sectors = bio_sectors(*bio);
> +               md_io_clone->rw = op_stat_group(bio_op(*bio));
>                 md_bitmap_start(mddev, md_io_clone);
>         }
>
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index c241119e6ef3..13e3f9ce1b79 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -850,6 +850,7 @@ struct md_io_clone {
>         unsigned long   start_time;
>         sector_t        offset;
>         unsigned long   sectors;
> +       enum stat_group rw;
>         struct bio      bio_clone;
>  };
>
> --
> 2.39.2
>
>

Reviewed-by: Xiao Ni <xni@redhat.com>