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

Chaitanya Kulkarni
2025-11-24T02:57:46Z

__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(-)

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);
--
2.40.0