[PATCH V2 1/2] block: move bio queue-transition flag fixups into blk_steal_bios()

Chaitanya Kulkarni
2026-02-26T03:13:27Z

blk_steal_bios() transfers bios from a request to a bio_list when the
request is requeued to a different queue. The NVMe multipath failover
path (nvme_failover_req) currently open-codes clearing of REQ_POLLED,
bi_cookie, and REQ_NOWAIT on each bio before calling blk_steal_bios().

Move these fixups into blk_steal_bios() itself so that any caller
automatically gets correct flag state when bios cross queue boundaries.
Simplify nvme_failover_req() accordingly.

Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
---
block/blk-mq.c | 17 +++++++++++++++++
drivers/nvme/host/multipath.c | 15 +--------------
2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index a29d8ac9d3e3..419b5c768af2 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3412,6 +3412,23 @@ EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
*/
void blk_steal_bios(struct bio_list *list, struct request *rq)
{
+ struct bio *bio;
+
+ for (bio = rq->bio; bio; bio = bio->bi_next) {
+ if (bio->bi_opf & REQ_POLLED) {
+ bio->bi_opf &= ~REQ_POLLED;
+ bio->bi_cookie = BLK_QC_T_NONE;
+ }
+ /*
+ * The alternate request queue that we may end up submitting
+ * the bio to may be frozen temporarily, in this case REQ_NOWAIT
+ * will fail the I/O immediately with EAGAIN to the issuer.
+ * We are not in the issuer context which cannot block. Clear
+ * the flag to avoid spurious EAGAIN I/O failures.
+ */
+ bio->bi_opf &= ~REQ_NOWAIT;
+ }
+
if (rq->bio) {
if (list->tail)
list->tail->bi_next = rq->bio;
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index bfcc5904e6a2..cda8a1e21f59 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -154,21 +154,8 @@ void nvme_failover_req(struct request *req)
}

spin_lock_irqsave(&ns->head->requeue_lock, flags);
- for (bio = req->bio; bio; bio = bio->bi_next) {
+ for (bio = req->bio; bio; bio = bio->bi_next)
bio_set_dev(bio, ns->head->disk->part0);
- if (bio->bi_opf & REQ_POLLED) {
- bio->bi_opf &= ~REQ_POLLED;
- bio->bi_cookie = BLK_QC_T_NONE;
- }
- /*
- * The alternate request queue that we may end up submitting
- * the bio to may be frozen temporarily, in this case REQ_NOWAIT
- * will fail the I/O immediately with EAGAIN to the issuer.
- * We are not in the issuer context which cannot block. Clear
- * the flag to avoid spurious EAGAIN I/O failures.
- */
- bio->bi_opf &= ~REQ_NOWAIT;
- }
blk_steal_bios(&ns->head->requeue_list, req);
spin_unlock_irqrestore(&ns->head->requeue_lock, flags);

--
2.39.5