2021-06-02 15:19:53

by Daniel Wagner

Subject: [PATCH v2] nvme: reset disk to the mpath node also when requeuing

Commit ce86dad222e9 ("nvme-multipath: reset bdev to ns head when
failover") moved the reset code where the bio is added to the
requeue_list for the failover path. But it left the original
bio_set_dev() in nvme_requeue_work().

Let's move the bio_set_dev() where we add the bio to the requeue_list
and avoid the double setting in case of the failover path. And this
makes the code more consistent.

Signed-off-by: Daniel Wagner <[email protected]>
---

v2: loop over all bios and reset them

drivers/nvme/host/multipath.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 127a17b4c13d..3334c6f23476 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -302,6 +302,7 @@ static blk_qc_t nvme_ns_head_submit_bio(struct bio *bio)
struct nvme_ns_head *head = bio->bi_bdev->bd_disk->private_data;
struct device *dev = disk_to_dev(head->disk);
struct nvme_ns *ns;
+ struct bio *b;
blk_qc_t ret = BLK_QC_T_NONE;
int srcu_idx;

@@ -324,6 +325,8 @@ static blk_qc_t nvme_ns_head_submit_bio(struct bio *bio)
dev_warn_ratelimited(dev, "no usable path - requeuing I/O\n");

spin_lock_irq(&head->requeue_lock);
+ for (b = bio; b; b = b->bi_next)
+ bio_set_dev(b, head->disk->part0);
bio_list_add(&head->requeue_list, bio);
spin_unlock_irq(&head->requeue_lock);
} else {
@@ -435,11 +438,6 @@ static void nvme_requeue_work(struct work_struct *work)
next = bio->bi_next;
bio->bi_next = NULL;

- /*
- * Reset disk to the mpath node and resubmit to select a new
- * path.
- */
- bio_set_dev(bio, head->disk->part0);
submit_bio_noacct(bio);
}
}
--
2.29.2

2021-06-03 07:27:06

by Christoph Hellwig

Subject: Re: [PATCH v2] nvme: reset disk to the mpath node also when requeuing

On Wed, Jun 02, 2021 at 03:00:39PM +0200, Daniel Wagner wrote:
> + struct bio *b;
> blk_qc_t ret = BLK_QC_T_NONE;
> int srcu_idx;
>
> @@ -324,6 +325,8 @@ static blk_qc_t nvme_ns_head_submit_bio(struct bio *bio)
> dev_warn_ratelimited(dev, "no usable path - requeuing I/O\n");
>
> spin_lock_irq(&head->requeue_lock);
> + for (b = bio; b; b = b->bi_next)
> + bio_set_dev(b, head->disk->part0);
> bio_list_add(&head->requeue_list, bio);
> spin_unlock_irq(&head->requeue_lock);
> } else {

I can't see why we'd need this hunk. bio->bi_bdev should have never been
changed to start with in this path.

> @@ -435,11 +438,6 @@ static void nvme_requeue_work(struct work_struct *work)
> next = bio->bi_next;
> bio->bi_next = NULL;
>
> - /*
> - * Reset disk to the mpath node and resubmit to select a new
> - * path.
> - */
> - bio_set_dev(bio, head->disk->part0);
> submit_bio_noacct(bio);
> }

This hunk looks fine.