[PATCH v3] nvme-multipath: expose path_state via sysfs

[PATCH v3] nvme-multipath: expose path_state via sysfs

[Guixin Liu]

Add a read-only "path_state" sysfs attribute to each NVMe path namespace
device (/sys/class/nvme/nvmeX/nvmeXcYnZ/path_state) that exposes the
current path state, including whether the path is enabled or disabled
with a specific reason.

Factor the path disable checks from nvme_path_is_disabled() into a new
nvme_path_get_state() helper that returns an enum nvme_path_state. This
keeps the path selection logic and sysfs reporting in sync, so any future
updates to the path disable criteria are automatically reflected in the
sysfs output.

Possible values:
  - "enabled (optimized)"     : ANA state is optimized
  - "enabled (non-optimized)" : ANA state is not optimized
  - "disabled (ctrl_down)"    : controller is not live
  - "disabled (ana_pending)"  : ANA state change pending
  - "disabled (ns_not_ready)" : namespace is not ready

This gives userspace visibility into the multipath path selection state
without requiring users to piece together controller state and namespace
flags manually.

Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
---
v2->v3:
- Factor path disable checks into nvme_path_get_state()
  helper returning enum nvme_path_state, and rebuild
  nvme_path_is_disabled() on top of it to keep path
  selection logic and sysfs reporting in sync.
  (Nilay Shroff)
- Distinguish "enabled (optimized)" vs
  "enabled (non-optimized)" based on ANA state.
  (Keith Busch)

v1->v2:
- Show specific disabled reason instead of just
  "disabled": "disabled (ctrl_down)",
  "disabled (ana_pending)",
  "disabled (ns_not_ready)". (Nilay Shroff)
---
 drivers/nvme/host/multipath.c | 47 ++++++++++++++++++++++++++++++-----
 drivers/nvme/host/nvme.h      |  1 +
 drivers/nvme/host/sysfs.c     |  4 ++-
 3 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index e033ede953cc..2da5e9da1866 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -288,7 +288,15 @@ void nvme_mpath_revalidate_paths(struct nvme_ns_head *head)
 	kblockd_schedule_work(&head->requeue_work);
 }
 
-static bool nvme_path_is_disabled(struct nvme_ns *ns)
+enum nvme_path_state {
+	NVME_PATH_ENABLED_OPTIMIZED,
+	NVME_PATH_ENABLED_NONOPTIMIZED,
+	NVME_PATH_DISABLED_CTRL_DOWN,
+	NVME_PATH_DISABLED_ANA_PENDING,
+	NVME_PATH_DISABLED_NS_NOT_READY,
+};
+
+static enum nvme_path_state nvme_path_get_state(struct nvme_ns *ns)
 {
 	enum nvme_ctrl_state state = nvme_ctrl_state(ns->ctrl);
 
@@ -298,11 +306,20 @@ static bool nvme_path_is_disabled(struct nvme_ns *ns)
 	 * Otherwise it will fail immediately and return to the requeue list.
 	 */
 	if (state != NVME_CTRL_LIVE && state != NVME_CTRL_DELETING)
-		return true;
-	if (test_bit(NVME_NS_ANA_PENDING, &ns->flags) ||
-	    !test_bit(NVME_NS_READY, &ns->flags))
-		return true;
-	return false;
+		return NVME_PATH_DISABLED_CTRL_DOWN;
+	if (test_bit(NVME_NS_ANA_PENDING, &ns->flags))
+		return NVME_PATH_DISABLED_ANA_PENDING;
+	if (!test_bit(NVME_NS_READY, &ns->flags))
+		return NVME_PATH_DISABLED_NS_NOT_READY;
+	if (nvme_ctrl_use_ana(ns->ctrl) &&
+	    ns->ana_state != NVME_ANA_OPTIMIZED)
+		return NVME_PATH_ENABLED_NONOPTIMIZED;
+	return NVME_PATH_ENABLED_OPTIMIZED;
+}
+
+static bool nvme_path_is_disabled(struct nvme_ns *ns)
+{
+	return nvme_path_get_state(ns) > NVME_PATH_ENABLED_NONOPTIMIZED;
 }
 
 static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
@@ -1101,6 +1118,24 @@ static ssize_t queue_depth_show(struct device *dev,
 }
 DEVICE_ATTR_RO(queue_depth);
 
+static const char * const nvme_path_state_names[] = {
+	[NVME_PATH_ENABLED_OPTIMIZED]		= "enabled (optimized)",
+	[NVME_PATH_ENABLED_NONOPTIMIZED]	= "enabled (non-optimized)",
+	[NVME_PATH_DISABLED_CTRL_DOWN]		= "disabled (ctrl_down)",
+	[NVME_PATH_DISABLED_ANA_PENDING]	= "disabled (ana_pending)",
+	[NVME_PATH_DISABLED_NS_NOT_READY]	= "disabled (ns_not_ready)",
+};
+
+static ssize_t path_state_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nvme_ns *ns = nvme_get_ns_from_dev(dev);
+
+	return sysfs_emit(buf, "%s\n",
+			  nvme_path_state_names[nvme_path_get_state(ns)]);
+}
+DEVICE_ATTR_RO(path_state);
+
 static ssize_t numa_nodes_show(struct device *dev, struct device_attribute *attr,
 		char *buf)
 {
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index b367c67dcb37..da59364d4774 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -1072,6 +1072,7 @@ extern struct device_attribute dev_attr_ana_grpid;
 extern struct device_attribute dev_attr_ana_state;
 extern struct device_attribute dev_attr_queue_depth;
 extern struct device_attribute dev_attr_numa_nodes;
+extern struct device_attribute dev_attr_path_state;
 extern struct device_attribute dev_attr_delayed_removal_secs;
 extern struct device_attribute dev_attr_multipath_failover_count;
 extern struct device_attribute dev_attr_io_requeue_no_usable_path_count;
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 933a5adfb7af..500d773300e7 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -261,6 +261,7 @@ static struct attribute *nvme_ns_attrs[] = {
 	&dev_attr_ana_state.attr,
 	&dev_attr_queue_depth.attr,
 	&dev_attr_numa_nodes.attr,
+	&dev_attr_path_state.attr,
 	&dev_attr_delayed_removal_secs.attr,
 #endif
 	&dev_attr_io_passthru_err_log_enabled.attr,
@@ -294,7 +295,8 @@ static umode_t nvme_ns_attrs_are_visible(struct kobject *kobj,
 		if (!nvme_ctrl_use_ana(nvme_get_ns_from_dev(dev)->ctrl))
 			return 0;
 	}
-	if (a == &dev_attr_queue_depth.attr || a == &dev_attr_numa_nodes.attr) {
+	if (a == &dev_attr_queue_depth.attr || a == &dev_attr_numa_nodes.attr ||
+	    a == &dev_attr_path_state.attr) {
 		if (nvme_disk_is_ns_head(dev_to_disk(dev)))
 			return 0;
 	}
-- 
2.43.7

Re: [PATCH v3] nvme-multipath: expose path_state via sysfs

[John Garry]

On 24/06/2026 06:48, Guixin Liu wrote:
> Add a read-only "path_state" sysfs attribute to each NVMe path namespace
> device (/sys/class/nvme/nvmeX/nvmeXcYnZ/path_state) that exposes the
> current path state, including whether the path is enabled or disabled
> with a specific reason.
> 
> Factor the path disable checks from nvme_path_is_disabled() into a new
> nvme_path_get_state() helper that returns an enum nvme_path_state. This
> keeps the path selection logic and sysfs reporting in sync, so any future
> updates to the path disable criteria are automatically reflected in the
> sysfs output.
> 
> Possible values:
>    - "enabled (optimized)"     : ANA state is optimized
>    - "enabled (non-optimized)" : ANA state is not optimized
>    - "disabled (ctrl_down)"    : controller is not live
>    - "disabled (ana_pending)"  : ANA state change pending
>    - "disabled (ns_not_ready)" : namespace is not ready
> 
> This gives userspace visibility into the multipath path selection state
> without requiring users to piece together controller state and namespace
> flags manually.
> 
> Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
> ---
> v2->v3:
> - Factor path disable checks into nvme_path_get_state()
>    helper returning enum nvme_path_state, and rebuild
>    nvme_path_is_disabled() on top of it to keep path
>    selection logic and sysfs reporting in sync.
>    (Nilay Shroff)
> - Distinguish "enabled (optimized)" vs
>    "enabled (non-optimized)" based on ANA state.
>    (Keith Busch)
> 
> v1->v2:
> - Show specific disabled reason instead of just
>    "disabled": "disabled (ctrl_down)",
>    "disabled (ana_pending)",
>    "disabled (ns_not_ready)". (Nilay Shroff)
> ---
>   drivers/nvme/host/multipath.c | 47 ++++++++++++++++++++++++++++++-----
>   drivers/nvme/host/nvme.h      |  1 +
>   drivers/nvme/host/sysfs.c     |  4 ++-
>   3 files changed, 45 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index e033ede953cc..2da5e9da1866 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -288,7 +288,15 @@ void nvme_mpath_revalidate_paths(struct nvme_ns_head *head)
>   	kblockd_schedule_work(&head->requeue_work);
>   }
>   
> -static bool nvme_path_is_disabled(struct nvme_ns *ns)
> +enum nvme_path_state {
> +	NVME_PATH_ENABLED_OPTIMIZED,
> +	NVME_PATH_ENABLED_NONOPTIMIZED,
> +	NVME_PATH_DISABLED_CTRL_DOWN,
> +	NVME_PATH_DISABLED_ANA_PENDING,
> +	NVME_PATH_DISABLED_NS_NOT_READY,
> +};
> +
> +static enum nvme_path_state nvme_path_get_state(struct nvme_ns *ns)
>   {
>   	enum nvme_ctrl_state state = nvme_ctrl_state(ns->ctrl);
>   
> @@ -298,11 +306,20 @@ static bool nvme_path_is_disabled(struct nvme_ns *ns)
>   	 * Otherwise it will fail immediately and return to the requeue list.
>   	 */
>   	if (state != NVME_CTRL_LIVE && state != NVME_CTRL_DELETING)
> -		return true;
> -	if (test_bit(NVME_NS_ANA_PENDING, &ns->flags) ||
> -	    !test_bit(NVME_NS_READY, &ns->flags))
> -		return true;
> -	return false;
> +		return NVME_PATH_DISABLED_CTRL_DOWN;
> +	if (test_bit(NVME_NS_ANA_PENDING, &ns->flags))
> +		return NVME_PATH_DISABLED_ANA_PENDING;
> +	if (!test_bit(NVME_NS_READY, &ns->flags))
> +		return NVME_PATH_DISABLED_NS_NOT_READY;
> +	if (nvme_ctrl_use_ana(ns->ctrl) &&
> +	    ns->ana_state != NVME_ANA_OPTIMIZED)
> +		return NVME_PATH_ENABLED_NONOPTIMIZED;
> +	return NVME_PATH_ENABLED_OPTIMIZED;
> +}
> +
> +static bool nvme_path_is_disabled(struct nvme_ns *ns)
> +{
> +	return nvme_path_get_state(ns) > NVME_PATH_ENABLED_NONOPTIMIZED;

I don't think that this is a particularly robust programming style, 
since nothing in enum nvme_path_state explicitly states that a very 
specific ordering or grouping is required


>   }
>   
>   static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
> @@ -1101,6 +1118,24 @@ static ssize_t queue_depth_show(struct device *dev,
>   }
>   DEVICE_ATTR_RO(queue_depth);
>   
> +static const char * const nvme_path_state_names[] = {
> +	[NVME_PATH_ENABLED_OPTIMIZED]		= "enabled (optimized)",
> +	[NVME_PATH_ENABLED_NONOPTIMIZED]	= "enabled (non-optimized)",
> +	[NVME_PATH_DISABLED_CTRL_DOWN]		= "disabled (ctrl_down)",
> +	[NVME_PATH_DISABLED_ANA_PENDING]	= "disabled (ana_pending)",
> +	[NVME_PATH_DISABLED_NS_NOT_READY]	= "disabled (ns_not_ready)",

some strings are abbreviated and some aren't

> +};
> +
> +static ssize_t path_state_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct nvme_ns *ns = nvme_get_ns_from_dev(dev);
> +
> +	return sysfs_emit(buf, "%s\n",
> +			  nvme_path_state_names[nvme_path_get_state(ns)]);

you should really check that nvme_path_get_state(ns) does not exceed 
indexing into ARRAY_SIZE(nvme_path_state_names)

> +}
> +DEVICE_ATTR_RO(path_state);
> +
>   static ssize_t numa_nodes_show(struct device *dev, struct device_attribute *attr,
>   		char *buf)
>   {
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index b367c67dcb37..da59364d4774 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -1072,6 +1072,7 @@ extern struct device_attribute dev_attr_ana_grpid;
>   extern struct device_attribute dev_attr_ana_state;
>   extern struct device_attribute dev_attr_queue_depth;
>   extern struct device_attribute dev_attr_numa_nodes;
> +extern struct device_attribute dev_attr_path_state;
>   extern struct device_attribute dev_attr_delayed_removal_secs;
>   extern struct device_attribute dev_attr_multipath_failover_count;
>   extern struct device_attribute dev_attr_io_requeue_no_usable_path_count;
> diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
> index 933a5adfb7af..500d773300e7 100644
> --- a/drivers/nvme/host/sysfs.c
> +++ b/drivers/nvme/host/sysfs.c
> @@ -261,6 +261,7 @@ static struct attribute *nvme_ns_attrs[] = {
>   	&dev_attr_ana_state.attr,
>   	&dev_attr_queue_depth.attr,
>   	&dev_attr_numa_nodes.attr,
> +	&dev_attr_path_state.attr,
>   	&dev_attr_delayed_removal_secs.attr,
>   #endif
>   	&dev_attr_io_passthru_err_log_enabled.attr,
> @@ -294,7 +295,8 @@ static umode_t nvme_ns_attrs_are_visible(struct kobject *kobj,
>   		if (!nvme_ctrl_use_ana(nvme_get_ns_from_dev(dev)->ctrl))
>   			return 0;
>   	}
> -	if (a == &dev_attr_queue_depth.attr || a == &dev_attr_numa_nodes.attr) {
> +	if (a == &dev_attr_queue_depth.attr || a == &dev_attr_numa_nodes.attr ||
> +	    a == &dev_attr_path_state.attr) {
>   		if (nvme_disk_is_ns_head(dev_to_disk(dev)))
>   			return 0;
>   	}

Re: [PATCH v3] nvme-multipath: expose path_state via sysfs

[Daniel Wagner]

On Wed, Jun 24, 2026 at 08:36:44AM +0100, John Garry wrote:
> On 24/06/2026 06:48, Guixin Liu wrote:
> > Add a read-only "path_state" sysfs attribute to each NVMe path namespace
> > device (/sys/class/nvme/nvmeX/nvmeXcYnZ/path_state) that exposes the
> > current path state, including whether the path is enabled or disabled
> > with a specific reason.
> > 
> > Factor the path disable checks from nvme_path_is_disabled() into a new
> > nvme_path_get_state() helper that returns an enum nvme_path_state. This
> > keeps the path selection logic and sysfs reporting in sync, so any future
> > updates to the path disable criteria are automatically reflected in the
> > sysfs output.
> > 
> > Possible values:
> >    - "enabled (optimized)"     : ANA state is optimized
> >    - "enabled (non-optimized)" : ANA state is not optimized
> >    - "disabled (ctrl_down)"    : controller is not live
> >    - "disabled (ana_pending)"  : ANA state change pending
> >    - "disabled (ns_not_ready)" : namespace is not ready

I'd prefer to have a single string here instead of something we might need
to parse again. The sysfs docs says

  Mixing types, expressing multiple lines of data, and doing fancy
  formatting of data is heavily frowned upon. Doing these things may get
  you publicly humiliated and your code rewritten without notice.

Something like

  - optimized
  - non-optimized
  - ctrl-down
  - ana-pending
  - ns-no-ready

BTW, the docs on sysfs say, these interfaces should be documented also
in Documentation/ABI. So far we haven't done this for the nvme
subsystem. Should we start with it? 

Re: [PATCH v3] nvme-multipath: expose path_state via sysfs

[Guixin Liu]

在 2026/6/24 15:36, John Garry 写道:
> On 24/06/2026 06:48, Guixin Liu wrote:
>> Add a read-only "path_state" sysfs attribute to each NVMe path namespace
>> device (/sys/class/nvme/nvmeX/nvmeXcYnZ/path_state) that exposes the
>> current path state, including whether the path is enabled or disabled
>> with a specific reason.
>>
>> Factor the path disable checks from nvme_path_is_disabled() into a new
>> nvme_path_get_state() helper that returns an enum nvme_path_state. This
>> keeps the path selection logic and sysfs reporting in sync, so any 
>> future
>> updates to the path disable criteria are automatically reflected in the
>> sysfs output.
>>
>> Possible values:
>>    - "enabled (optimized)"     : ANA state is optimized
>>    - "enabled (non-optimized)" : ANA state is not optimized
>>    - "disabled (ctrl_down)"    : controller is not live
>>    - "disabled (ana_pending)"  : ANA state change pending
>>    - "disabled (ns_not_ready)" : namespace is not ready
>>
>> This gives userspace visibility into the multipath path selection state
>> without requiring users to piece together controller state and namespace
>> flags manually.
>>
>> Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
>> ---
>> v2->v3:
>> - Factor path disable checks into nvme_path_get_state()
>>    helper returning enum nvme_path_state, and rebuild
>>    nvme_path_is_disabled() on top of it to keep path
>>    selection logic and sysfs reporting in sync.
>>    (Nilay Shroff)
>> - Distinguish "enabled (optimized)" vs
>>    "enabled (non-optimized)" based on ANA state.
>>    (Keith Busch)
>>
>> v1->v2:
>> - Show specific disabled reason instead of just
>>    "disabled": "disabled (ctrl_down)",
>>    "disabled (ana_pending)",
>>    "disabled (ns_not_ready)". (Nilay Shroff)
>> ---
>>   drivers/nvme/host/multipath.c | 47 ++++++++++++++++++++++++++++++-----
>>   drivers/nvme/host/nvme.h      |  1 +
>>   drivers/nvme/host/sysfs.c     |  4 ++-
>>   3 files changed, 45 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/nvme/host/multipath.c 
>> b/drivers/nvme/host/multipath.c
>> index e033ede953cc..2da5e9da1866 100644
>> --- a/drivers/nvme/host/multipath.c
>> +++ b/drivers/nvme/host/multipath.c
>> @@ -288,7 +288,15 @@ void nvme_mpath_revalidate_paths(struct 
>> nvme_ns_head *head)
>>       kblockd_schedule_work(&head->requeue_work);
>>   }
>>   -static bool nvme_path_is_disabled(struct nvme_ns *ns)
>> +enum nvme_path_state {
>> +    NVME_PATH_ENABLED_OPTIMIZED,
>> +    NVME_PATH_ENABLED_NONOPTIMIZED,
>> +    NVME_PATH_DISABLED_CTRL_DOWN,
>> +    NVME_PATH_DISABLED_ANA_PENDING,
>> +    NVME_PATH_DISABLED_NS_NOT_READY,
>> +};
>> +
>> +static enum nvme_path_state nvme_path_get_state(struct nvme_ns *ns)
>>   {
>>       enum nvme_ctrl_state state = nvme_ctrl_state(ns->ctrl);
>>   @@ -298,11 +306,20 @@ static bool nvme_path_is_disabled(struct 
>> nvme_ns *ns)
>>        * Otherwise it will fail immediately and return to the requeue 
>> list.
>>        */
>>       if (state != NVME_CTRL_LIVE && state != NVME_CTRL_DELETING)
>> -        return true;
>> -    if (test_bit(NVME_NS_ANA_PENDING, &ns->flags) ||
>> -        !test_bit(NVME_NS_READY, &ns->flags))
>> -        return true;
>> -    return false;
>> +        return NVME_PATH_DISABLED_CTRL_DOWN;
>> +    if (test_bit(NVME_NS_ANA_PENDING, &ns->flags))
>> +        return NVME_PATH_DISABLED_ANA_PENDING;
>> +    if (!test_bit(NVME_NS_READY, &ns->flags))
>> +        return NVME_PATH_DISABLED_NS_NOT_READY;
>> +    if (nvme_ctrl_use_ana(ns->ctrl) &&
>> +        ns->ana_state != NVME_ANA_OPTIMIZED)
>> +        return NVME_PATH_ENABLED_NONOPTIMIZED;
>> +    return NVME_PATH_ENABLED_OPTIMIZED;
>> +}
>> +
>> +static bool nvme_path_is_disabled(struct nvme_ns *ns)
>> +{
>> +    return nvme_path_get_state(ns) > NVME_PATH_ENABLED_NONOPTIMIZED;
>
> I don't think that this is a particularly robust programming style, 
> since nothing in enum nvme_path_state explicitly states that a very 
> specific ordering or grouping is required
>
I think so, should add NVME_PATH_DISABLED_FIRST to identify the
start of the disabled state.
>
>>   }
>>     static struct nvme_ns *__nvme_find_path(struct nvme_ns_head 
>> *head, int node)
>> @@ -1101,6 +1118,24 @@ static ssize_t queue_depth_show(struct device 
>> *dev,
>>   }
>>   DEVICE_ATTR_RO(queue_depth);
>>   +static const char * const nvme_path_state_names[] = {
>> +    [NVME_PATH_ENABLED_OPTIMIZED]        = "enabled (optimized)",
>> +    [NVME_PATH_ENABLED_NONOPTIMIZED]    = "enabled (non-optimized)",
>> +    [NVME_PATH_DISABLED_CTRL_DOWN]        = "disabled (ctrl_down)",
>> +    [NVME_PATH_DISABLED_ANA_PENDING]    = "disabled (ana_pending)",
>> +    [NVME_PATH_DISABLED_NS_NOT_READY]    = "disabled (ns_not_ready)",
>
> some strings are abbreviated and some aren't
   "enabled (optimized)"
   "enabled (non-optimized)"
   "disabled (controller down)"
   "disabled (ana pending)"
   "disabled (namespace not ready)"
is this OK?
>
>> +};
>> +
>> +static ssize_t path_state_show(struct device *dev,
>> +        struct device_attribute *attr, char *buf)
>> +{
>> +    struct nvme_ns *ns = nvme_get_ns_from_dev(dev);
>> +
>> +    return sysfs_emit(buf, "%s\n",
>> + nvme_path_state_names[nvme_path_get_state(ns)]);
>
> you should really check that nvme_path_get_state(ns) does not exceed 
> indexing into ARRAY_SIZE(nvme_path_state_names)
Changed in v4, thanks.

Best Regards,
Guixin Liu

Re: [PATCH v3] nvme-multipath: expose path_state via sysfs

[Guixin Liu]

在 2026/6/24 17:55, Daniel Wagner 写道:
> On Wed, Jun 24, 2026 at 08:36:44AM +0100, John Garry wrote:
>> On 24/06/2026 06:48, Guixin Liu wrote:
>>> Add a read-only "path_state" sysfs attribute to each NVMe path namespace
>>> device (/sys/class/nvme/nvmeX/nvmeXcYnZ/path_state) that exposes the
>>> current path state, including whether the path is enabled or disabled
>>> with a specific reason.
>>>
>>> Factor the path disable checks from nvme_path_is_disabled() into a new
>>> nvme_path_get_state() helper that returns an enum nvme_path_state. This
>>> keeps the path selection logic and sysfs reporting in sync, so any future
>>> updates to the path disable criteria are automatically reflected in the
>>> sysfs output.
>>>
>>> Possible values:
>>>     - "enabled (optimized)"     : ANA state is optimized
>>>     - "enabled (non-optimized)" : ANA state is not optimized
>>>     - "disabled (ctrl_down)"    : controller is not live
>>>     - "disabled (ana_pending)"  : ANA state change pending
>>>     - "disabled (ns_not_ready)" : namespace is not ready
> I'd prefer to have a single string here instead of something we might need
> to parse again. The sysfs docs says
>
>    Mixing types, expressing multiple lines of data, and doing fancy
>    formatting of data is heavily frowned upon. Doing these things may get
>    you publicly humiliated and your code rewritten without notice.
>
> Something like
>
>    - optimized
>    - non-optimized
>    - ctrl-down
>    - ana-pending
>    - ns-no-ready
Would this be redundant with ana_state?

Is this OK?
     - enabled
     - ctrl-down
     - ana-pending
     - ns-not-ready


CC Keith, John, Nilay, what do you think?
>
> BTW, the docs on sysfs say, these interfaces should be documented also
> in Documentation/ABI. So far we haven't done this for the nvme
> subsystem. Should we start with it?
Sure, just like the nvme-multipath.rst file I worked on earlier,
I can do this later with the help of AI.

Best Regards,
Guixin Liu

Re: [PATCH v3] nvme-multipath: expose path_state via sysfs

[Nilay Shroff]

On 6/24/26 5:22 PM, Guixin Liu wrote:
> 
> 
> 在 2026/6/24 17:55, Daniel Wagner 写道:
>> On Wed, Jun 24, 2026 at 08:36:44AM +0100, John Garry wrote:
>>> On 24/06/2026 06:48, Guixin Liu wrote:
>>>> Add a read-only "path_state" sysfs attribute to each NVMe path namespace
>>>> device (/sys/class/nvme/nvmeX/nvmeXcYnZ/path_state) that exposes the
>>>> current path state, including whether the path is enabled or disabled
>>>> with a specific reason.
>>>>
>>>> Factor the path disable checks from nvme_path_is_disabled() into a new
>>>> nvme_path_get_state() helper that returns an enum nvme_path_state. This
>>>> keeps the path selection logic and sysfs reporting in sync, so any future
>>>> updates to the path disable criteria are automatically reflected in the
>>>> sysfs output.
>>>>
>>>> Possible values:
>>>>     - "enabled (optimized)"     : ANA state is optimized
>>>>     - "enabled (non-optimized)" : ANA state is not optimized
>>>>     - "disabled (ctrl_down)"    : controller is not live
>>>>     - "disabled (ana_pending)"  : ANA state change pending
>>>>     - "disabled (ns_not_ready)" : namespace is not ready
>> I'd prefer to have a single string here instead of something we might need
>> to parse again. The sysfs docs says
>>
>>    Mixing types, expressing multiple lines of data, and doing fancy
>>    formatting of data is heavily frowned upon. Doing these things may get
>>    you publicly humiliated and your code rewritten without notice.
>>
>> Something like
>>
>>    - optimized
>>    - non-optimized
>>    - ctrl-down
>>    - ana-pending
>>    - ns-no-ready
> Would this be redundant with ana_state?
> 
> Is this OK?
>      - enabled
>      - ctrl-down
>      - ana-pending
>      - ns-not-ready
> 
> 
> CC Keith, John, Nilay, what do you think?

I tend to agree with Daniel about both mixing types and
reporting ana state values here as ana state is also reported
separately.

The purpose of path_state is really to expose whether the path
is currently eligible for path selection and, if not, why.

IMO, a simpler set of values which you suggested above
should be sufficient. But lets wait if Keith has any
other suggestion.

Thanks
--Nilay

Re: [PATCH v3] nvme-multipath: expose path_state via sysfs

[Guixin Liu]

在 2026/6/24 21:21, Nilay Shroff 写道:
> On 6/24/26 5:22 PM, Guixin Liu wrote:
>>
>>
>> 在 2026/6/24 17:55, Daniel Wagner 写道:
>>> On Wed, Jun 24, 2026 at 08:36:44AM +0100, John Garry wrote:
>>>> On 24/06/2026 06:48, Guixin Liu wrote:
>>>>> Add a read-only "path_state" sysfs attribute to each NVMe path 
>>>>> namespace
>>>>> device (/sys/class/nvme/nvmeX/nvmeXcYnZ/path_state) that exposes the
>>>>> current path state, including whether the path is enabled or disabled
>>>>> with a specific reason.
>>>>>
>>>>> Factor the path disable checks from nvme_path_is_disabled() into a 
>>>>> new
>>>>> nvme_path_get_state() helper that returns an enum nvme_path_state. 
>>>>> This
>>>>> keeps the path selection logic and sysfs reporting in sync, so any 
>>>>> future
>>>>> updates to the path disable criteria are automatically reflected 
>>>>> in the
>>>>> sysfs output.
>>>>>
>>>>> Possible values:
>>>>>     - "enabled (optimized)"     : ANA state is optimized
>>>>>     - "enabled (non-optimized)" : ANA state is not optimized
>>>>>     - "disabled (ctrl_down)"    : controller is not live
>>>>>     - "disabled (ana_pending)"  : ANA state change pending
>>>>>     - "disabled (ns_not_ready)" : namespace is not ready
>>> I'd prefer to have a single string here instead of something we 
>>> might need
>>> to parse again. The sysfs docs says
>>>
>>>    Mixing types, expressing multiple lines of data, and doing fancy
>>>    formatting of data is heavily frowned upon. Doing these things 
>>> may get
>>>    you publicly humiliated and your code rewritten without notice.
>>>
>>> Something like
>>>
>>>    - optimized
>>>    - non-optimized
>>>    - ctrl-down
>>>    - ana-pending
>>>    - ns-no-ready
>> Would this be redundant with ana_state?
>>
>> Is this OK?
>>      - enabled
>>      - ctrl-down
>>      - ana-pending
>>      - ns-not-ready
>>
>>
>> CC Keith, John, Nilay, what do you think?
>
> I tend to agree with Daniel about both mixing types and
> reporting ana state values here as ana state is also reported
> separately.
>
> The purpose of path_state is really to expose whether the path
> is currently eligible for path selection and, if not, why.
>
> IMO, a simpler set of values which you suggested above
> should be sufficient. But lets wait if Keith has any
> other suggestion.
>
> Thanks
> --Nilay
>
Hi Keith, would you have any suggestions on this?

Best Regards,
Guixin Liu