This patch adds support for the pr_ops read_reservation callout by
calling the NVMe Reservation Report helper. It then parses that info to
detect if there is a reservation and if there is then convert the
returned info to a pr_ops pr_held_reservation struct.

Signed-off-by: Mike Christie <michael.chris...@oracle.com>
---
 drivers/nvme/host/pr.c | 79 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/drivers/nvme/host/pr.c b/drivers/nvme/host/pr.c
index 5c4611d15d9c..87a0aaf811f4 100644
--- a/drivers/nvme/host/pr.c
+++ b/drivers/nvme/host/pr.c
@@ -30,6 +30,18 @@ static enum nvme_pr_type nvme_pr_type_from_blk(enum pr_type 
type)
        return 0;
 }
 
+static enum pr_type block_pr_type_from_nvme(enum nvme_pr_type type)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(nvme_pr_types); i++) {
+               if (nvme_pr_types[i].nvme_type == type)
+                       return nvme_pr_types[i].blk_type;
+       }
+
+       return 0;
+}
+
 static int nvme_send_ns_head_pr_command(struct block_device *bdev,
                struct nvme_command *c, u8 *data, unsigned int data_len)
 {
@@ -194,6 +206,72 @@ static int nvme_pr_read_keys(struct block_device *bdev,
        return ret;
 }
 
+static int nvme_pr_read_reservation(struct block_device *bdev,
+               struct pr_held_reservation *resv)
+{
+       struct nvme_reservation_status tmp_status, *status;
+       int ret, i, num_regs;
+       u32 data_len;
+       bool eds;
+       u8 *data;
+
+       memset(resv, 0, sizeof(*resv));
+retry:
+       /*
+        * Get the number of registrations so we know how big to allocate
+        * the response buffer.
+        */
+       ret = nvme_pr_resv_report(bdev, (u8 *)&tmp_status, sizeof(tmp_status),
+                                 &eds);
+       if (ret)
+               return 0;
+
+       num_regs = get_unaligned_le16(&tmp_status.regctl);
+       if (!num_regs) {
+               resv->generation = le32_to_cpu(tmp_status.gen);
+               return 0;
+       }
+
+       data_len = sizeof(*status) +
+                       num_regs * sizeof(struct nvme_registered_ctrl_ext);
+       data = kzalloc(data_len, GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       ret = nvme_pr_resv_report(bdev, data, data_len, &eds);
+       if (ret)
+               goto free_data;
+       status = (struct nvme_reservation_status *)data;
+
+       if (num_regs != get_unaligned_le16(&status->regctl)) {
+               kfree(data);
+               goto retry;
+       }
+
+       resv->generation = le32_to_cpu(status->gen);
+       resv->type = block_pr_type_from_nvme(status->rtype);
+
+       for (i = 0; i < num_regs; i++) {
+               if (eds) {
+                       if (status->regctl_eds[i].rcsts) {
+                               resv->key =
+                                       le64_to_cpu(status->regctl_eds[i].rkey);
+                               break;
+                       }
+               } else {
+                       if (status->regctl_ds[i].rcsts) {
+                               resv->key =
+                                       le64_to_cpu(status->regctl_ds[i].rkey);
+                               break;
+                       }
+               }
+       }
+
+free_data:
+       kfree(data);
+       return ret;
+}
+
 const struct pr_ops nvme_pr_ops = {
        .pr_register    = nvme_pr_register,
        .pr_reserve     = nvme_pr_reserve,
@@ -201,4 +279,5 @@ const struct pr_ops nvme_pr_ops = {
        .pr_preempt     = nvme_pr_preempt,
        .pr_clear       = nvme_pr_clear,
        .pr_read_keys   = nvme_pr_read_keys,
+       .pr_read_reservation = nvme_pr_read_reservation,
 };
-- 
2.25.1

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