Re: [PATCH V2 2/5] dm: ignore discard return value

Yu Kuai
2025-11-24T06:26:20Z

Hi,

在 2025/11/24 10:57, Chaitanya Kulkarni 写道:
> __blkdev_issue_discard() always returns 0, making all error checking
> at call sites dead code.
>
> For dm-thin change issue_discard() return type to void, in
> passdown_double_checking_shared_status() remove the r assignment from
> return value of the issue_discard(), for end_discard() hardcod value
> of r to 0 that matches only value returned from
> __blkdev_issue_discard().
>
> md part is simplified to only check !discard_bio by ignoring the
> __blkdev_issue_discard() value.
>
> Signed-off-by: Chaitanya Kulkarni <ckulkarnilinux@gmail.com>
> ---
> drivers/md/dm-thin.c | 12 +++++-------
> drivers/md/md.c | 4 ++--
> 2 files changed, 7 insertions(+), 9 deletions(-)

mdraid and dm are different drivers, please split them.

>
> diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> index c84149ba4e38..77c76f75c85f 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
> @@ -395,13 +395,13 @@ static void begin_discard(struct discard_op *op, struct thin_c *tc, struct bio *
> op->bio = NULL;
> }
>
> -static int issue_discard(struct discard_op *op, dm_block_t data_b, dm_block_t data_e)
> +static void issue_discard(struct discard_op *op, dm_block_t data_b, dm_block_t data_e)
> {
> struct thin_c *tc = op->tc;
> sector_t s = block_to_sectors(tc->pool, data_b);
> sector_t len = block_to_sectors(tc->pool, data_e - data_b);
>
> - return __blkdev_issue_discard(tc->pool_dev->bdev, s, len, GFP_NOIO, &op->bio);
> + __blkdev_issue_discard(tc->pool_dev->bdev, s, len, GFP_NOIO, &op->bio);
> }
>
> static void end_discard(struct discard_op *op, int r)
> @@ -1113,9 +1113,7 @@ static void passdown_double_checking_shared_status(struct dm_thin_new_mapping *m
> break;
> }
>
> - r = issue_discard(&op, b, e);
> - if (r)
> - goto out;
> + issue_discard(&op, b, e);
>
> b = e;
> }
> @@ -1188,8 +1186,8 @@ static void process_prepared_discard_passdown_pt1(struct dm_thin_new_mapping *m)
> struct discard_op op;
>
> begin_discard(&op, tc, discard_parent);
> - r = issue_discard(&op, m->data_block, data_end);
> - end_discard(&op, r);
> + issue_discard(&op, m->data_block, data_end);
> + end_discard(&op, 0);
> }
> }
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 7b5c5967568f..aeb62df39828 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -9132,8 +9132,8 @@ void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
> {
> struct bio *discard_bio = NULL;
>
> - if (__blkdev_issue_discard(rdev->bdev, start, size, GFP_NOIO,
> - &discard_bio) || !discard_bio)
> + __blkdev_issue_discard(rdev->bdev, start, size, GFP_NOIO, &discard_bio);
> + if (!discard_bio)
> return;
>
> bio_chain(discard_bio, bio);

--
Thanks
Kuai