[PATCH] nvme: fix handling single range discard request

Ming Lei
2023-03-03T23:14:09Z

When investigating one customer report on warning in nvme_setup_discard,
we observed the controller(nvme/tcp) actually exposes
queue_max_discard_segments(req->q) == 1.

Obviously the current code can't handle this situation, since contiguity
merge like normal RW request is taken.

Fix the issue by building range from request sector/nr_sectors directly.

Fixes: b35ba01ea697 ("nvme: support ranged discard requests")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
drivers/nvme/host/core.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index c2730b116dc6..d4be525f8100 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -781,16 +781,26 @@ static blk_status_t nvme_setup_discard(struct nvme_ns *ns, struct request *req,
range = page_address(ns->ctrl->discard_page);
}

- __rq_for_each_bio(bio, req) {
- u64 slba = nvme_sect_to_lba(ns, bio->bi_iter.bi_sector);
- u32 nlb = bio->bi_iter.bi_size >> ns->lba_shift;
-
- if (n < segments) {
- range[n].cattr = cpu_to_le32(0);
- range[n].nlb = cpu_to_le32(nlb);
- range[n].slba = cpu_to_le64(slba);
+ if (queue_max_discard_segments(req->q) == 1) {
+ u64 slba = nvme_sect_to_lba(ns, blk_rq_pos(req));
+ u32 nlb = blk_rq_sectors(req) >> (ns->lba_shift - 9);
+
+ range[0].cattr = cpu_to_le32(0);
+ range[0].nlb = cpu_to_le32(nlb);
+ range[0].slba = cpu_to_le64(slba);
+ n = 1;
+ } else {
+ __rq_for_each_bio(bio, req) {
+ u64 slba = nvme_sect_to_lba(ns, bio->bi_iter.bi_sector);
+ u32 nlb = bio->bi_iter.bi_size >> ns->lba_shift;
+
+ if (n < segments) {
+ range[n].cattr = cpu_to_le32(0);
+ range[n].nlb = cpu_to_le32(nlb);
+ range[n].slba = cpu_to_le64(slba);
+ }
+ n++;
}
- n++;
}

if (WARN_ON_ONCE(n != segments)) {
--
2.39.2