nvme: implement ->get_unique_id

Implement the get_unique_id method to allow pNFS SCSI layout access to
NVMe namespaces.

This is the server side implementation of RFC 9561 "Using the Parallel
NFS (pNFS) SCSI Layout to Access Non-Volatile Memory Express (NVMe)
Storage Devices".
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/host/core.c

@@ -2285,6 +2285,32 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_ns_info *info)
 	return ret;
 }
 
+int nvme_ns_get_unique_id(struct nvme_ns *ns, u8 id[16],
+		enum blk_unique_id type)
+{
+	struct nvme_ns_ids *ids = &ns->head->ids;
+
+	if (type != BLK_UID_EUI64)
+		return -EINVAL;
+
+	if (memchr_inv(ids->nguid, 0, sizeof(ids->nguid))) {
+		memcpy(id, &ids->nguid, sizeof(ids->nguid));
+		return sizeof(ids->nguid);
+	}
+	if (memchr_inv(ids->eui64, 0, sizeof(ids->eui64))) {
+		memcpy(id, &ids->eui64, sizeof(ids->eui64));
+		return sizeof(ids->eui64);
+	}
+
+	return -EINVAL;
+}
+
+static int nvme_get_unique_id(struct gendisk *disk, u8 id[16],
+		enum blk_unique_id type)
+{
+	return nvme_ns_get_unique_id(disk->private_data, id, type);
+}
+
 #ifdef CONFIG_BLK_SED_OPAL
 static int nvme_sec_submit(void *data, u16 spsp, u8 secp, void *buffer, size_t len,
 		bool send)
@@ -2340,6 +2366,7 @@ const struct block_device_operations nvme_bdev_ops = {
 	.open		= nvme_open,
 	.release	= nvme_release,
 	.getgeo		= nvme_getgeo,
+	.get_unique_id	= nvme_get_unique_id,
 	.report_zones	= nvme_report_zones,
 	.pr_ops		= &nvme_pr_ops,
 };

drivers/nvme/host/multipath.c

@@ -488,6 +488,21 @@ static void nvme_ns_head_release(struct gendisk *disk)
 	nvme_put_ns_head(disk->private_data);
 }
 
+static int nvme_ns_head_get_unique_id(struct gendisk *disk, u8 id[16],
+		enum blk_unique_id type)
+{
+	struct nvme_ns_head *head = disk->private_data;
+	struct nvme_ns *ns;
+	int srcu_idx, ret = -EWOULDBLOCK;
+
+	srcu_idx = srcu_read_lock(&head->srcu);
+	ns = nvme_find_path(head);
+	if (ns)
+		ret = nvme_ns_get_unique_id(ns, id, type);
+	srcu_read_unlock(&head->srcu, srcu_idx);
+	return ret;
+}
+
 #ifdef CONFIG_BLK_DEV_ZONED
 static int nvme_ns_head_report_zones(struct gendisk *disk, sector_t sector,
 		unsigned int nr_zones, report_zones_cb cb, void *data)
@@ -515,6 +530,7 @@ const struct block_device_operations nvme_ns_head_ops = {
 	.ioctl		= nvme_ns_head_ioctl,
 	.compat_ioctl	= blkdev_compat_ptr_ioctl,
 	.getgeo		= nvme_getgeo,
+	.get_unique_id	= nvme_ns_head_get_unique_id,
 	.report_zones	= nvme_ns_head_report_zones,
 	.pr_ops		= &nvme_pr_ops,
 };

drivers/nvme/host/nvme.h

@@ -1059,6 +1059,9 @@ static inline bool nvme_disk_is_ns_head(struct gendisk *disk)
 }
 #endif /* CONFIG_NVME_MULTIPATH */
 
+int nvme_ns_get_unique_id(struct nvme_ns *ns, u8 id[16],
+		enum blk_unique_id type);
+
 struct nvme_zone_info {
 	u64 zone_size;
 	unsigned int max_open_zones;