[PATCH v2 11/20] nvme: Add pr_ops read_reservation support

[Mike Christie]

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.christie at oracle.com>
---
 drivers/nvme/host/core.c | 68 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 230e5deca391..5bbc1d84a87e 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2267,6 +2267,73 @@ 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(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,
@@ -2274,6 +2341,7 @@ 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,
 };
 
 #ifdef CONFIG_BLK_SED_OPAL
-- 
2.18.2