Re: [f2fs-dev] [PATCH V3 4/6] nvmet: ignore discard return value

Yongpeng Yang
2025-11-26T10:14:39Z

On 11/25/25 07:48, Chaitanya Kulkarni wrote:
> __blkdev_issue_discard() always returns 0, making the error checking
> in nvmet_bdev_discard_range() dead code.
>
> Kill the function nvmet_bdev_discard_range() and call
> __blkdev_issue_discard() directly from nvmet_bdev_execute_discard(),
> since no error handling is needed anymore for __blkdev_issue_discard()
> call.
>
> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Chaitanya Kulkarni <ckulkarnilinux@gmail.com>
> ---
> drivers/nvme/target/io-cmd-bdev.c | 28 +++++++---------------------
> 1 file changed, 7 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
> index 8d246b8ca604..ca7731048940 100644
> --- a/drivers/nvme/target/io-cmd-bdev.c
> +++ b/drivers/nvme/target/io-cmd-bdev.c
> @@ -362,29 +362,14 @@ u16 nvmet_bdev_flush(struct nvmet_req *req)
> return 0;
> }
>
> -static u16 nvmet_bdev_discard_range(struct nvmet_req *req,
> - struct nvme_dsm_range *range, struct bio **bio)
> -{
> - struct nvmet_ns *ns = req->ns;
> - int ret;
> -
> - ret = __blkdev_issue_discard(ns->bdev,
> - nvmet_lba_to_sect(ns, range->slba),
> - le32_to_cpu(range->nlb) << (ns->blksize_shift - 9),
> - GFP_KERNEL, bio);
> - if (ret && ret != -EOPNOTSUPP) {
> - req->error_slba = le64_to_cpu(range->slba);
> - return errno_to_nvme_status(req, ret);
> - }
> - return NVME_SC_SUCCESS;
> -}
> -
> static void nvmet_bdev_execute_discard(struct nvmet_req *req)
> {
> + struct nvmet_ns *ns = req->ns;
> struct nvme_dsm_range range;
> struct bio *bio = NULL;
> + sector_t nr_sects;
> int i;
> - u16 status;
> + u16 status = NVME_SC_SUCCESS;
>
> for (i = 0; i <= le32_to_cpu(req->cmd->dsm.nr); i++) {
> status = nvmet_copy_from_sgl(req, i * sizeof(range), &range,
> @@ -392,9 +377,10 @@ static void nvmet_bdev_execute_discard(struct nvmet_req *req)
> if (status)
> break;
>
> - status = nvmet_bdev_discard_range(req, &range, &bio);
> - if (status)
> - break;
> + nr_sects = le32_to_cpu(range.nlb) << (ns->blksize_shift - 9);
> + __blkdev_issue_discard(ns->bdev,
> + nvmet_lba_to_sect(ns, range.slba), nr_sects,
> + GFP_KERNEL, &bio);

We also need to check for memory allocation errors in
__blkdev_issue_discard(). However, this cannot be done by simply
checking if bio is NULL. Similar to the issue with xfs_discard_extents,
once __blkdev_issue_discard()->blk_alloc_discard_bio() succeeds once,
any subsequent memory allocation failures cannot be detected by checking
if bio is NULL.

Yongpeng,

> }
>
> if (bio) {