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

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Message-Id: <4D5FB87E-13F7-4F61-85E6-F52E4245F37C@suse.com>
Date: Wed, 28 May 2025 15:04:41 +0800
From: Glass Su <glass.su@...e.com>
To: Yu Kuai <yukuai1@...weicloud.com>
Cc: hch@....de,
 xni@...hat.com,
 colyli@...nel.org,
 song@...nel.org,
 yukuai3@...wei.com,
 linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 linux-raid@...r.kernel.org,
 yi.zhang@...wei.com,
 yangerkun@...wei.com,
 johnny.chenyi@...wei.com
Subject: Re: [PATCH 04/23] md/md-bitmap: support discard for bitmap ops



> On May 24, 2025, at 14:13, Yu Kuai <yukuai1@...weicloud.com> wrote:
> 
> From: Yu Kuai <yukuai3@...wei.com>
> 
> Use two new methods {start, end}_discard to handle discard IO, prepare
> to support new md bitmap.
> 
> Signed-off-by: Yu Kuai <yukuai3@...wei.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;

Please also mention the change in commit message.

— 
Su
> struct bio bio_clone;
> };
> 
> -- 
> 2.39.2
> 
>