[PATCH] nvme-sysfs: add 'fna' attribute

[PATCH] nvme-sysfs: add 'fna' attribute

[Tokunori Ikegami]

The fna attriute is needed for the format NVM command.

Signed-off-by: Tokunori Ikegami <ikegami.t@gmail.com>
---
 drivers/nvme/host/core.c  |  1 +
 drivers/nvme/host/nvme.h  |  1 +
 drivers/nvme/host/sysfs.c | 13 +++++++++++++
 3 files changed, 15 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ca9959a8fb9e..0ecb7cbabbed 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3302,6 +3302,7 @@ static int nvme_init_identify(struct nvme_ctrl *ctrl)
 	ctrl->cctemp = le16_to_cpu(id->cctemp);
 
 	atomic_set(&ctrl->abort_limit, id->acl + 1);
+	ctrl->fna = id->fna;
 	ctrl->vwc = id->vwc;
 	if (id->mdts)
 		max_hw_sectors = nvme_mps_to_sectors(ctrl, id->mdts);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 313a4f978a2c..3df0fbaadb04 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -328,6 +328,7 @@ struct nvme_ctrl {
 	u16 sqsize;
 	u32 max_namespaces;
 	atomic_t abort_limit;
+	u8 fna;
 	u8 vwc;
 	u32 vs;
 	u32 sgls;
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index eb345551d6fe..816a869306df 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -546,6 +546,18 @@ static ssize_t dctype_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(dctype);
 
+static ssize_t fna_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+	if (ctrl->fna)
+		return sysfs_emit(buf, "%02x\n", ctrl->fna);
+
+	return 0;
+}
+static DEVICE_ATTR_RO(fna);
+
 #ifdef CONFIG_NVME_HOST_AUTH
 static ssize_t nvme_ctrl_dhchap_secret_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
@@ -687,6 +699,7 @@ static struct attribute *nvme_dev_attrs[] = {
 	&dev_attr_kato.attr,
 	&dev_attr_cntrltype.attr,
 	&dev_attr_dctype.attr,
+	&dev_attr_fna.attr,
 #ifdef CONFIG_NVME_HOST_AUTH
 	&dev_attr_dhchap_secret.attr,
 	&dev_attr_dhchap_ctrl_secret.attr,
-- 
2.43.0

Re: [PATCH] nvme-sysfs: add 'fna' attribute

[Keith Busch]

On Sun, Sep 22, 2024 at 12:45:53AM +0900, Tokunori Ikegami wrote:
> The fna attriute is needed for the format NVM command.

At least for multi-namespace subsystems, I would agree knowing this
value is important to understand the potentially undesired reprecussions
of running a format command, but that logic ought to just go in tooling.
And the meaning of the reported value here is not immediately obvious to
a typical user without the spec in front of you, so I'm a little
skeptical on exporting this attribute.

nvme-cli already checks this on a format request, at least. You probably
are not formatting very frequently anyway, so avoiding an identify
command for such a low frequency event seems a bit overkill to me.

Re: [PATCH] nvme-sysfs: add 'fna' attribute

[Tokunori Ikegami]

There are many identify commands fields so if the nvme driver can be 
kept the field values seems can be reduced to run many identify 
commands. Thank you.

On 2024/09/23 0:36, Keith Busch wrote:
> At least for multi-namespace subsystems, I would agree knowing this
> value is important to understand the potentially undesired reprecussions
> of running a format command, but that logic ought to just go in tooling.
> And the meaning of the reported value here is not immediately obvious to
> a typical user without the spec in front of you, so I'm a little
> skeptical on exporting this attribute.
>
> nvme-cli already checks this on a format request, at least. You probably
> are not formatting very frequently anyway, so avoiding an identify
> command for such a low frequency event seems a bit overkill to me.