Re: [PATCH v11 1/1] nvmet: support reservation feature

[Dmitry Bogdanov <d.bogdanov@yadro.com>]

On Sun, Sep 29, 2024 at 11:14:10AM +0800, Guixin Liu wrote:
> This patch implements the reservation feature, includes:
> 1. reservation register(register, unregister and replace).
> 2. reservation acquire(acquire, preempt, preempt and abort).
> 3. reservation release(release and clear).
> 4. reservation report.
> 5. set feature and get feature of reservation notify mask.
> 6. get log page of reservation event.
> 
> And also make reservation configurable, one can set ns to support
> reservation before enable ns. The default of resv_enable is false.
> 
> Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
> ---
>  drivers/nvme/target/Makefile      |    2 +-
>  drivers/nvme/target/admin-cmd.c   |   24 +-
>  drivers/nvme/target/configfs.c    |   27 +
>  drivers/nvme/target/core.c        |   56 +-
>  drivers/nvme/target/fabrics-cmd.c |    4 +-
>  drivers/nvme/target/nvmet.h       |   50 +-
>  drivers/nvme/target/pr.c          | 1177 +++++++++++++++++++++++++++++
>  include/linux/nvme.h              |   54 ++
>  8 files changed, 1382 insertions(+), 12 deletions(-)
>  create mode 100644 drivers/nvme/target/pr.c
> 
> diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
> index bd87dfd173a4..9a56269cefd0 100644
> --- a/drivers/nvme/target/configfs.c
> +++ b/drivers/nvme/target/configfs.c
> @@ -748,6 +748,32 @@ static ssize_t nvmet_ns_revalidate_size_store(struct config_item *item,
> 
>  CONFIGFS_ATTR_WO(nvmet_ns_, revalidate_size);
> 
> +static ssize_t nvmet_ns_resv_enable_show(struct config_item *item, char *page)
> +{
> +       return sprintf(page, "%d\n", to_nvmet_ns(item)->pr.enable);

sysfs_emit is to be used in show()

> +}
> +


> +
> +static void nvmet_execute_pr_report(struct nvmet_req *req)
> +{
> +       u32 cdw11 = le32_to_cpu(req->cmd->common.cdw11);
> +       u32 cdw10 = le32_to_cpu(req->cmd->common.cdw10);
> +       u32 num_bytes = 4 * (cdw10 + 1); /* cdw10 is number of dwords */
> +       u8 eds = cdw11 & 1; /* Extended data structure, bit 00 */
> +       struct nvme_registered_ctrl_ext *ctrl_eds;
> +       struct nvme_reservation_status_ext *data;
> +       struct nvmet_pr *pr = &req->ns->pr;
> +       struct nvmet_pr_registrant *holder;
> +       struct nvmet_pr_registrant *reg;
> +       u16 num_ctrls = 0;
> +       u16 status;
> +       u8 rtype;
> +
> +       /* nvmet hostid(uuid_t) is 128 bit. */
> +       if (!eds) {
> +               req->error_loc = offsetof(struct nvme_common_command, cdw11);
> +               status = NVME_SC_HOST_ID_INCONSIST | NVME_SC_DNR;
> +               goto out;
> +       }
> +
> +       if (num_bytes < sizeof(struct nvme_reservation_status_ext)) {
> +               req->error_loc = offsetof(struct nvme_common_command, cdw10);
> +               status = NVME_SC_INVALID_FIELD | NVME_SC_DNR;
> +               goto out;
> +       }
> +
> +       data = kmalloc(num_bytes, GFP_KERNEL);
> +       if (!data) {
> +               status = NVME_SC_INTERNAL;
> +               goto out;
> +       }
> +       memset(data, 0, num_bytes);
> +       data->gen = cpu_to_le32(atomic_read(&pr->generation));
> +       data->ptpls = 0;
> +       ctrl_eds = data->regctl_eds;
> +
> +       rcu_read_lock();
> +       holder = rcu_dereference(pr->holder);
> +       rtype = holder ? holder->rtype : 0;
> +       data->rtype = rtype;
> +
> +       list_for_each_entry_rcu(reg, &pr->registrant_list, entry) {
> +               if ((void *)ctrl_eds >= (void *)(data + num_bytes))
> +                       break;
> +               /*
> +                * Dynamic controller, set cntlid to 0xffff.
> +                */
> +               ctrl_eds->cntlid = 0xffff;
> +               if (rtype == NVME_PR_WRITE_EXCLUSIVE_ALL_REGS ||
> +                   rtype == NVME_PR_EXCLUSIVE_ACCESS_ALL_REGS)
> +                       ctrl_eds->rcsts = 1;
> +               if (holder && uuid_equal(&reg->hostid, &holder->hostid))

is just (reg == holder) not enough here?

> +                       ctrl_eds->rcsts = 1;
> +               uuid_copy((uuid_t *)&ctrl_eds->hostid, &reg->hostid);
> +               ctrl_eds->rkey = cpu_to_le64(reg->rkey);
> +               ctrl_eds++;
> +               num_ctrls++;
> +       }
> +       rcu_read_unlock();
> +
> +       put_unaligned_le16(num_ctrls, data->regctl);

Here you should report the number of all registered registrants in ns,
not the only reported. It is used by the host to understand that it got
not a full response.
NUMD field (cdw11) is about transfering the response. But the structure itsef in
the reposnse has to be complete.

> +       status = nvmet_copy_to_sgl(req, 0, data, num_bytes);
> +       kfree(data);
> +out:
> +       nvmet_req_complete(req, status);
> +}
> +

BR,
 Dmitry