[RFC v1] nvme: add cse, ds, ms, nsze 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.

Signed-off-by: Daniel Wagner <dwagner@xxxxxxx>
---

As discussed during ALPPS, these here are the missing attribures which libnvme
is still looking up via commands. I've tested this with a modified libnvme and
didn't observe any ioctls anymore.

I'm pretty sure the naming is a bit off for the variables. Not really sure if we
want to stick to the spec naming sceme or have our own one, e.g. 'nsze' vs
'capacity'.

Also getting a pointer to the nvme_ns data structure is a bit strange
(dev_to_nvme_ns). This stip is necessary as many of the ns attributes are in
nvme_ns. Shouldn't these per path values not all be the same and thus couldn't
these be in nvme_ns_head? Anyway, just not sure who to deal with this. So any
pointers highly welcomed!

Cheers,
Daniel

 drivers/nvme/host/core.c  |  2 ++
 drivers/nvme/host/nvme.h  |  2 ++
 drivers/nvme/host/sysfs.c | 72 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 80673ea63fea..f100ee241bd7 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2029,6 +2029,8 @@ 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->lba_shift = id->lbaf[lbaf].ds;
+	ns->nsze = le64_to_cpu(id->nsze);
+	ns->nuse = le64_to_cpu(id->nuse);
 	nvme_set_queue_limits(ns->ctrl, ns->queue);
 
 	nvme_configure_metadata(ns, id);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index f35647c470af..97652bf2c787 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -487,6 +487,8 @@ struct nvme_ns {
 	struct nvme_ns_head *head;
 
 	int lba_shift;
+	u64 nsze;
+	u64 nuse;
 	u16 ms;
 	u16 pi_size;
 	u16 sgs;
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 212e1b05d298..b46faee50361 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -114,12 +114,84 @@ static ssize_t nsid_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(nsid);
 
+static struct nvme_ns *dev_to_nvme_ns(struct device *dev)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+
+	if (disk->fops == &nvme_bdev_ops)
+		return nvme_get_ns_from_dev(dev);
+	else {
+		struct nvme_ns_head *head = disk->private_data;
+		struct nvme_subsystem *subsys = head->subsys;
+		struct nvme_ctrl *ctrl;
+		struct nvme_ns *ns, *ret = NULL;
+
+		list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry) {
+			down_read(&ctrl->namespaces_rwsem);
+			list_for_each_entry(ns, &ctrl->namespaces, list) {
+				ret = ns;
+				break;
+			}
+			up_read(&ctrl->namespaces_rwsem);
+		}
+		return ret;
+	}
+}
+
+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 lba_ds_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct nvme_ns *ns = dev_to_nvme_ns(dev);
+
+	return sysfs_emit(buf, "%d\n", ns->lba_shift);
+}
+static DEVICE_ATTR_RO(lba_ds);
+
+static ssize_t lba_ms_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct nvme_ns *ns = dev_to_nvme_ns(dev);
+
+	return sysfs_emit(buf, "%d\n", ns->ms);
+}
+static DEVICE_ATTR_RO(lba_ms);
+
+static ssize_t nsze_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct nvme_ns *ns = dev_to_nvme_ns(dev);
+
+	return sysfs_emit(buf, "%llu\n", ns->nsze);
+}
+static DEVICE_ATTR_RO(nsze);
+
+static ssize_t nuse_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	struct nvme_ns *ns = dev_to_nvme_ns(dev);
+
+	return sysfs_emit(buf, "%llu\n", ns->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_lba_ds.attr,
+	&dev_attr_lba_ms.attr,
+	&dev_attr_nsze.attr,
+	&dev_attr_nuse.attr,
 #ifdef CONFIG_NVME_MULTIPATH
 	&dev_attr_ana_grpid.attr,
 	&dev_attr_ana_state.attr,
-- 
2.43.0