[PATCH V2 1/1] nvme: introduce generic per-namespace chardev
Minwoo Im
minwoo.im.dev at gmail.com
Wed Apr 7 16:47:30 BST 2021
On 21-04-08 00:35:36, Minwoo Im wrote:
> On 21-04-07 16:21:52, Christoph Hellwig wrote:
> > On Wed, Apr 07, 2021 at 11:11:28PM +0900, Minwoo Im wrote:
> > > Then can we have like this ? The following diff is just considering the
> > > ns_head only, but just conceptually, not hanging out with bdev, it's
> > > just get the reference.
> >
> > FYI, this is what I did today. Not really tested yet and at least
> > one known issue. Busy with calls for now, but I hope to have something
> > ready tonight:
> >
> > http://git.infradead.org/users/hch/block.git/shortlog/refs/heads/nvme-generic
>
> Here's an additional patch based on the branch above:
>
> 1. During the `nvme list` command, controller ioctl for the ns_head has
> been not coming out from the mutex_lock_killable(&nvme_subsystems_lock)
> because it just gets the controller reference and return it without
> unlocking it. So the first change point of this patch is to unlock the
> mutex right before the return. But, Is this a real issue? because
> this changes are not from this series though.....
>
> 2. Can we have the check whether the ns_head has disk allocated or not
> by getting `disk` pointer out of the #ifdef CONFIG_NVME_MULTIPATH?
> If it's not allocated due to some reasons (e.g., !multipath, or CMIC
> does not support multiple controllers, or some failures during the
> allocations), disk will never be allocated. So, I tried to pull the
> `disk` pointer out of the #ifdef from the nvme_ns_head, but maybe
> this is not what you have intended.... It would be great if you can
> give some feedback on this.
>
> I had a quick tests based on the branch with the following patch:
> - !CONFIG_NVME_MULTIPATH
> - CONFIG_NVME_MULTIPATH && !multipath
Forgot to mention a case:
- CONFIG_NVME_MULTIPATH && multipath
> - Basic I/O for /dev/ng* chardev through `nvme io-passthru` command.
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 2b04fc451f09..f05eff5b7c30 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -2016,6 +2016,7 @@ struct nvme_ctrl *nvme_find_get_live_ctrl(struct nvme_subsystem *subsys)
> if (ctrl->state != NVME_CTRL_LIVE)
> continue;
> nvme_get_ctrl(ctrl);
> + mutex_unlock(&nvme_subsystems_lock);
> return ctrl;
> }
>
> @@ -3687,8 +3688,8 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid,
> nvme_get_ctrl(ctrl);
>
> device_add_disk(ctrl->device, ns->disk, nvme_ns_id_attr_groups);
> - // XXX: only for the !multipath case
> - nvme_add_ns_cdev(ns);
> + if (!nvme_ns_head_multipath(ns->head))
> + nvme_add_ns_cdev(ns);
>
> nvme_mpath_add_disk(ns, id);
> nvme_fault_inject_init(&ns->fault_inject, ns->disk->disk_name);
> @@ -3733,8 +3734,8 @@ static void nvme_ns_remove(struct nvme_ns *ns)
> synchronize_srcu(&ns->head->srcu); /* wait for concurrent submissions */
>
> if (ns->disk->flags & GENHD_FL_UP) {
> - // XXX: only for !multipath
> - cdev_device_del(&ns->cdev, &ns->cdev_device);
> + if (!nvme_ns_head_multipath(ns->head))
> + cdev_device_del(&ns->cdev, &ns->cdev_device);
> del_gendisk(ns->disk);
> blk_cleanup_queue(ns->queue);
> if (blk_get_integrity(ns->disk))
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index dc1846d3e4f2..91ff75b41ed6 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -417,8 +417,9 @@ struct nvme_ns_head {
> struct cdev cdev;
> struct device cdev_device;
>
> -#ifdef CONFIG_NVME_MULTIPATH
> struct gendisk *disk;
> +
> +#ifdef CONFIG_NVME_MULTIPATH
> struct bio_list requeue_list;
> spinlock_t requeue_lock;
> struct work_struct requeue_work;
> @@ -429,6 +430,11 @@ struct nvme_ns_head {
> #endif
> };
>
> +static inline bool nvme_ns_head_multipath(struct nvme_ns_head *head)
> +{
> + return !!head->disk;
> +}
> +
> enum nvme_ns_features {
> NVME_NS_EXT_LBAS = 1 << 0, /* support extended LBA format */
> NVME_NS_METADATA_SUPPORTED = 1 << 1, /* support getting generated md */
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