[PATCH v3 4/4] nvme: add csi, ms and nuse to sysfs

[Daniel Wagner]

libnvme is using the sysfs for enumarating the nvme resources. Though
there are few missing attritbutes in the sysfs. For these libnvme issues
commands during discovering.

As the kernel already knows all these attributes and we would like to
avoid libnvme to issue commands all the time, expose these missing
attributes.

The nuse value is updated on request because the nuse is a volatile
value. Since any user can read the sysfs attribute, a very simple rate
limit is added (update max every 5 seconds). A more sophisticated update
strategy can be added later if there is actually a need for it.

Signed-off-by: Daniel Wagner <dwagner@xxxxxxx>
---
 drivers/nvme/host/core.c  | 28 ++++++++++++++++++++++++++++
 drivers/nvme/host/nvme.h  |  2 ++
 drivers/nvme/host/sysfs.c | 31 +++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index caa52c2f57c8..e7dd64ee1653 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1663,6 +1663,33 @@ static void nvme_ns_release(struct nvme_ns *ns)
 	nvme_put_ns(ns);
 }
 
+int nvme_ns_update_nuse(struct nvme_ns_head *head)
+{
+	static DEFINE_RATELIMIT_STATE(_rs, 5 * HZ, 1);
+	struct nvme_id_ns *id;
+	struct nvme_ns *ns;
+	int srcu_idx, ret = -EWOULDBLOCK;
+
+	if (__ratelimit(&_rs))
+		return 0;
+
+	srcu_idx = srcu_read_lock(&head->srcu);
+	ns = nvme_find_path(head);
+	if (!ns)
+		goto out_unlock;
+
+	ret = nvme_identify_ns(ns->ctrl, head->ns_id, &id);
+	if (ret)
+		goto out_unlock;
+
+	head->nuse = le64_to_cpu(id->nuse);
+	kfree(id);
+
+out_unlock:
+	srcu_read_unlock(&head->srcu, srcu_idx);
+	return ret;
+}
+
 static int nvme_open(struct gendisk *disk, blk_mode_t mode)
 {
 	return nvme_ns_open(disk->private_data);
@@ -2068,6 +2095,7 @@ static int nvme_update_ns_info_block(struct nvme_ns *ns,
 	blk_mq_freeze_queue(ns->disk->queue);
 	lbaf = nvme_lbaf_index(id->flbas);
 	ns->head->lba_shift = id->lbaf[lbaf].ds;
+	ns->head->nuse = le64_to_cpu(id->nuse);
 	nvme_set_queue_limits(ns->ctrl, ns->queue);
 
 	ret = nvme_configure_metadata(ns, id);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index e6c7890b14c9..6a928646dc09 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -456,6 +456,7 @@ struct nvme_ns_head {
 	u16			pi_size;
 	u16			sgs;
 	u32			sws;
+	u64			nuse;
 	u8			pi_type;
 	u8			guard_type;
 #ifdef CONFIG_BLK_DEV_ZONED
@@ -867,6 +868,7 @@ int nvme_ns_chr_uring_cmd(struct io_uring_cmd *ioucmd,
 		unsigned int issue_flags);
 int nvme_ns_head_chr_uring_cmd(struct io_uring_cmd *ioucmd,
 		unsigned int issue_flags);
+int nvme_ns_update_nuse(struct nvme_ns_head *head);
 int nvme_getgeo(struct block_device *bdev, struct hd_geometry *geo);
 int nvme_dev_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags);
 
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index c6b7fbd4d34d..c24854eca496 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -114,12 +114,43 @@ static ssize_t nsid_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(nsid);
 
+static ssize_t csi_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	return sysfs_emit(buf, "%d\n", dev_to_ns_head(dev)->ids.csi);
+}
+static DEVICE_ATTR_RO(csi);
+
+static ssize_t metadata_bytes_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", dev_to_ns_head(dev)->ms);
+}
+static DEVICE_ATTR_RO(metadata_bytes);
+
+static ssize_t nuse_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct nvme_ns_head *head = dev_to_ns_head(dev);
+	int ret;
+
+	ret = nvme_ns_update_nuse(head);
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "%llu\n", head->nuse);
+}
+static DEVICE_ATTR_RO(nuse);
+
 static struct attribute *nvme_ns_id_attrs[] = {
 	&dev_attr_wwid.attr,
 	&dev_attr_uuid.attr,
 	&dev_attr_nguid.attr,
 	&dev_attr_eui.attr,
+	&dev_attr_csi.attr,
 	&dev_attr_nsid.attr,
+	&dev_attr_metadata_bytes.attr,
+	&dev_attr_nuse.attr,
 #ifdef CONFIG_NVME_MULTIPATH
 	&dev_attr_ana_grpid.attr,
 	&dev_attr_ana_state.attr,
-- 
2.43.0