[PATCH 2/2] nvme: delete disk when last path is gone
Minwoo Im
minwoo.im.dev at gmail.com
Tue Feb 23 07:56:56 EST 2021
On 21-02-23 12:59:22, Hannes Reinecke wrote:
> The multipath code currently deletes the disk only after all references
> to it are dropped rather than when the last path to that disk is lost.
> This has been reported to cause problems with some use cases like MD RAID.
>
> This patch implements an alternative behaviour of deleting the disk when
> the last path is gone, ie the same behaviour as non-multipathed nvme
> devices. The new behaviour will be selected with the 'fail_if_no_path'
> attribute, as returning it's arguably the same functionality.
>
> Suggested-by: Keith Busch <kbusch at kernel.org>
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> ---
> drivers/nvme/host/core.c | 1 +
> drivers/nvme/host/multipath.c | 3 ++-
> drivers/nvme/host/nvme.h | 17 +++++++++++++++--
> 3 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 2fb3ecc0c53b..d717a6283d6e 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -542,6 +542,7 @@ static void nvme_free_ns_head(struct kref *ref)
> container_of(ref, struct nvme_ns_head, ref);
>
> nvme_mpath_remove_disk(head);
> + nvme_mpath_put_disk(head);
> ida_simple_remove(&head->subsys->ns_ida, head->instance);
> cleanup_srcu_struct(&head->srcu);
> nvme_put_subsystem(head->subsys);
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index d5773ea105b1..f995b8234622 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -724,6 +724,8 @@ void nvme_mpath_add_disk(struct nvme_ns *ns, struct nvme_id_ns *id)
>
> void nvme_mpath_remove_disk(struct nvme_ns_head *head)
> {
> + if (test_bit(NVME_NSHEAD_FAIL_IF_NO_PATH, &head->flags))
> + return;
> if (!head->disk)
> return;
> if (head->disk->flags & GENHD_FL_UP)
> @@ -741,7 +743,6 @@ void nvme_mpath_remove_disk(struct nvme_ns_head *head)
> */
> head->disk->queue = NULL;
> }
> - put_disk(head->disk);
> }
>
> int nvme_mpath_init(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index 3d2513f8194d..e6efa085f08a 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -681,8 +681,12 @@ static inline void nvme_mpath_check_last_path(struct nvme_ns *ns)
> {
> struct nvme_ns_head *head = ns->head;
>
> - if (head->disk && list_empty(&head->list))
> - kblockd_schedule_work(&head->requeue_work);
> + if (head->disk && list_empty(&head->list)) {
> + if (test_bit(NVME_NSHEAD_FAIL_IF_NO_PATH, &head->flags))
> + nvme_mpath_remove_disk(head);
Does it need to call nvme_mpath_remove_disk here ? It looks like it
returns with nothing right away if NVME_NSHEAD_FAIL_IF_NO_PATH is set.
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