Message-ID: <1931444790.41757055603941.JavaMail.epsvc@epcpadp1new>
Date: Thu, 4 Sep 2025 19:03:57 +0530
From: Neeraj Kumar <s.neeraj@...sung.com>
To: Dave Jiang <dave.jiang@...el.com>
Cc: linux-cxl@...r.kernel.org, nvdimm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, gost.dev@...sung.com,
	a.manzanares@...sung.com, vishak.g@...sung.com, neeraj.kernel@...il.com,
	cpgs@...sung.com
Subject: Re: [PATCH V2 02/20] nvdimm/label: Prep patch to accommodate cxl
 lsa 2.1 support

On 18/08/25 02:48PM, Dave Jiang wrote:
>
>
>On 7/30/25 5:11 AM, Neeraj Kumar wrote:
>> LSA 2.1 format introduces region label, which can also reside
>> into LSA along with only namespace label as per v1.1 and v1.2
>>
>> As both namespace and region labels are of same size of 256 bytes.
>> Thus renamed "struct nd_namespace_label" to "struct nd_lsa_label",
>> where both namespace label and region label can stay as union.
>>
>> No functional change introduced.
>>
>> Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>
>> ---
>>  drivers/nvdimm/label.c          | 58 +++++++++++++++++++--------------
>>  drivers/nvdimm/label.h          | 12 ++++++-
>>  drivers/nvdimm/namespace_devs.c | 33 +++++++++++++------
>>  drivers/nvdimm/nd.h             |  2 +-
>>  4 files changed, 68 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c
>> index 7a011ee02d79..75bc11da4c11 100644
>> --- a/drivers/nvdimm/label.c
>> +++ b/drivers/nvdimm/label.c
>> @@ -271,7 +271,7 @@ static void nd_label_copy(struct nvdimm_drvdata *ndd,
>>  	memcpy(dst, src, sizeof_namespace_index(ndd));
>>  }
>>
>> -static struct nd_namespace_label *nd_label_base(struct nvdimm_drvdata *ndd)
>> +static struct nd_lsa_label *nd_label_base(struct nvdimm_drvdata *ndd)
>
>This function caught my eye. I think that given the way it's being used, maybe it should be returning 'unsigned long' instead of a struct given every instance it's being used, it gets converted back to 'unsigned long'.
>
>$ git grep -n nd_label_base
>label.c:274:static struct nd_lsa_label *nd_label_base(struct nvdimm_drvdata *ndd)
>label.c:287:    base = (unsigned long) nd_label_base(ndd);
>label.c:296:    base = (unsigned long) nd_label_base(ndd);
>label.c:782:    offset = (unsigned long) nd_label_base(ndd)
>

Yes Dave, Its added long back (4a826c83db4ed). Sure I will fix it in
next patch-set.

>>  {
>>  	void *base = to_namespace_index(ndd, 0);
>>
>> @@ -279,7 +279,7 @@ static struct nd_namespace_label *nd_label_base(struct nvdimm_drvdata *ndd)
>>  }
>>
>>  static int to_slot(struct nvdimm_drvdata *ndd,
>> -		struct nd_namespace_label *nd_label)
>> +		struct nd_lsa_label *nd_label)
>>  {
>>  	unsigned long label, base;
>>
>> @@ -289,14 +289,14 @@ static int to_slot(struct nvdimm_drvdata *ndd,
>>  	return (label - base) / sizeof_namespace_label(ndd);
>>  }
>>
>> -static struct nd_namespace_label *to_label(struct nvdimm_drvdata *ndd, int slot)
>> +static struct nd_lsa_label *to_label(struct nvdimm_drvdata *ndd, int slot)
>>  {
>>  	unsigned long label, base;
>>
>>  	base = (unsigned long) nd_label_base(ndd);
>>  	label = base + sizeof_namespace_label(ndd) * slot;
>>
>> -	return (struct nd_namespace_label *) label;
>> +	return (struct nd_lsa_label *) label;
>>  }
>>
>>  #define for_each_clear_bit_le(bit, addr, size) \
>> @@ -382,9 +382,10 @@ static void nsl_calculate_checksum(struct nvdimm_drvdata *ndd,
>>  }
>>
>>  static bool slot_valid(struct nvdimm_drvdata *ndd,
>> -		struct nd_namespace_label *nd_label, u32 slot)
>> +		struct nd_lsa_label *lsa_label, u32 slot)
>>  {
>>  	bool valid;
>> +	struct nd_namespace_label *nd_label = &lsa_label->ns_label;
>>
>>  	/* check that we are written where we expect to be written */
>>  	if (slot != nsl_get_slot(ndd, nd_label))
>> @@ -405,6 +406,7 @@ int nd_label_reserve_dpa(struct nvdimm_drvdata *ndd)
>>  		return 0; /* no label, nothing to reserve */
>>
>>  	for_each_clear_bit_le(slot, free, nslot) {
>> +		struct nd_lsa_label *lsa_label;
>>  		struct nd_namespace_label *nd_label;
>>  		struct nd_region *nd_region = NULL;
>>  		struct nd_label_id label_id;
>> @@ -412,9 +414,10 @@ int nd_label_reserve_dpa(struct nvdimm_drvdata *ndd)
>>  		uuid_t label_uuid;
>>  		u32 flags;
>>
>> -		nd_label = to_label(ndd, slot);
>> +		lsa_label = to_label(ndd, slot);
>> +		nd_label = &lsa_label->ns_label;
>>
>> -		if (!slot_valid(ndd, nd_label, slot))
>> +		if (!slot_valid(ndd, lsa_label, slot))
>>  			continue;
>>
>>  		nsl_get_uuid(ndd, nd_label, &label_uuid);
>> @@ -565,11 +568,13 @@ int nd_label_active_count(struct nvdimm_drvdata *ndd)
>>  		return 0;
>>
>>  	for_each_clear_bit_le(slot, free, nslot) {
>> +		struct nd_lsa_label *lsa_label;
>>  		struct nd_namespace_label *nd_label;
>>
>> -		nd_label = to_label(ndd, slot);
>> +		lsa_label = to_label(ndd, slot);
>> +		nd_label = &lsa_label->ns_label;
>>
>> -		if (!slot_valid(ndd, nd_label, slot)) {
>> +		if (!slot_valid(ndd, lsa_label, slot)) {
>>  			u32 label_slot = nsl_get_slot(ndd, nd_label);
>>  			u64 size = nsl_get_rawsize(ndd, nd_label);
>>  			u64 dpa = nsl_get_dpa(ndd, nd_label);
>> @@ -584,7 +589,7 @@ int nd_label_active_count(struct nvdimm_drvdata *ndd)
>>  	return count;
>>  }
>>
>> -struct nd_namespace_label *nd_label_active(struct nvdimm_drvdata *ndd, int n)
>> +struct nd_lsa_label *nd_label_active(struct nvdimm_drvdata *ndd, int n)
>>  {
>>  	struct nd_namespace_index *nsindex;
>>  	unsigned long *free;
>> @@ -594,10 +599,10 @@ struct nd_namespace_label *nd_label_active(struct nvdimm_drvdata *ndd, int n)
>>  		return NULL;
>>
>>  	for_each_clear_bit_le(slot, free, nslot) {
>> -		struct nd_namespace_label *nd_label;
>> +		struct nd_lsa_label *lsa_label;
>>
>> -		nd_label = to_label(ndd, slot);
>> -		if (!slot_valid(ndd, nd_label, slot))
>> +		lsa_label = to_label(ndd, slot);
>> +		if (!slot_valid(ndd, lsa_label, slot))
>>  			continue;
>>
>>  		if (n-- == 0)
>> @@ -738,7 +743,7 @@ static int nd_label_write_index(struct nvdimm_drvdata *ndd, int index, u32 seq,
>>  }
>>
>>  static unsigned long nd_label_offset(struct nvdimm_drvdata *ndd,
>> -		struct nd_namespace_label *nd_label)
>> +		struct nd_lsa_label *nd_label)
>>  {
>>  	return (unsigned long) nd_label
>>  		- (unsigned long) to_namespace_index(ndd, 0);
>> @@ -892,6 +897,7 @@ static int __pmem_label_update(struct nd_region *nd_region,
>>  	struct nd_namespace_common *ndns = &nspm->nsio.common;
>>  	struct nd_interleave_set *nd_set = nd_region->nd_set;
>>  	struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
>> +	struct nd_lsa_label *lsa_label;
>>  	struct nd_namespace_label *nd_label;
>>  	struct nd_namespace_index *nsindex;
>>  	struct nd_label_ent *label_ent;
>> @@ -923,8 +929,10 @@ static int __pmem_label_update(struct nd_region *nd_region,
>>  		return -ENXIO;
>>  	dev_dbg(ndd->dev, "allocated: %d\n", slot);
>>
>> -	nd_label = to_label(ndd, slot);
>> -	memset(nd_label, 0, sizeof_namespace_label(ndd));
>> +	lsa_label = to_label(ndd, slot);
>> +	memset(lsa_label, 0, sizeof_namespace_label(ndd));
>> +
>> +	nd_label = &lsa_label->ns_label;
>>  	nsl_set_uuid(ndd, nd_label, nspm->uuid);
>>  	nsl_set_name(ndd, nd_label, nspm->alt_name);
>>  	nsl_set_flags(ndd, nd_label, flags);
>> @@ -942,7 +950,7 @@ static int __pmem_label_update(struct nd_region *nd_region,
>>  	nd_dbg_dpa(nd_region, ndd, res, "\n");
>>
>>  	/* update label */
>> -	offset = nd_label_offset(ndd, nd_label);
>> +	offset = nd_label_offset(ndd, lsa_label);
>>  	rc = nvdimm_set_config_data(ndd, offset, nd_label,
>>  			sizeof_namespace_label(ndd));
>>  	if (rc < 0)
>> @@ -954,7 +962,7 @@ static int __pmem_label_update(struct nd_region *nd_region,
>>  		if (!label_ent->label)
>>  			continue;
>>  		if (test_and_clear_bit(ND_LABEL_REAP, &label_ent->flags) ||
>> -		    nsl_uuid_equal(ndd, label_ent->label, nspm->uuid))
>> +		    nsl_uuid_equal(ndd, &label_ent->label->ns_label, nspm->uuid))
>>  			reap_victim(nd_mapping, label_ent);
>>  	}
>>
>> @@ -964,14 +972,14 @@ static int __pmem_label_update(struct nd_region *nd_region,
>>  	if (rc == 0) {
>>  		list_for_each_entry(label_ent, &nd_mapping->labels, list)
>>  			if (!label_ent->label) {
>> -				label_ent->label = nd_label;
>> -				nd_label = NULL;
>> +				label_ent->label = lsa_label;
>> +				lsa_label = NULL;
>>  				break;
>>  			}
>> -		dev_WARN_ONCE(&nspm->nsio.common.dev, nd_label,
>> +		dev_WARN_ONCE(&nspm->nsio.common.dev, lsa_label,
>>  				"failed to track label: %d\n",
>> -				to_slot(ndd, nd_label));
>> -		if (nd_label)
>> +				to_slot(ndd, lsa_label));
>> +		if (lsa_label)
>>  			rc = -ENXIO;
>>  	}
>>  	mutex_unlock(&nd_mapping->lock);
>> @@ -1042,12 +1050,12 @@ static int del_labels(struct nd_mapping *nd_mapping, uuid_t *uuid)
>>
>>  	mutex_lock(&nd_mapping->lock);
>>  	list_for_each_entry_safe(label_ent, e, &nd_mapping->labels, list) {
>> -		struct nd_namespace_label *nd_label = label_ent->label;
>> +		struct nd_lsa_label *nd_label = label_ent->label;
>>
>>  		if (!nd_label)
>>  			continue;
>>  		active++;
>> -		if (!nsl_uuid_equal(ndd, nd_label, uuid))
>> +		if (!nsl_uuid_equal(ndd, &nd_label->ns_label, uuid))
>>  			continue;
>>  		active--;
>>  		slot = to_slot(ndd, nd_label);
>> diff --git a/drivers/nvdimm/label.h b/drivers/nvdimm/label.h
>> index 0650fb4b9821..4883b3a1320f 100644
>> --- a/drivers/nvdimm/label.h
>> +++ b/drivers/nvdimm/label.h
>> @@ -183,6 +183,16 @@ struct nd_namespace_label {
>>  	};
>>  };
>>
>> +/*
>> + * LSA 2.1 format introduces region label, which can also reside
>> + * into LSA along with only namespace label as per v1.1 and v1.2
>> + */
>> +struct nd_lsa_label {
>> +	union {
>> +		struct nd_namespace_label ns_label;
>> +	};
>> +};
>> +
>>  #define NVDIMM_BTT_GUID "8aed63a2-29a2-4c66-8b12-f05d15d3922a"
>>  #define NVDIMM_BTT2_GUID "18633bfc-1735-4217-8ac9-17239282d3f8"
>>  #define NVDIMM_PFN_GUID "266400ba-fb9f-4677-bcb0-968f11d0d225"
>> @@ -215,7 +225,7 @@ struct nvdimm_drvdata;
>>  int nd_label_data_init(struct nvdimm_drvdata *ndd);
>>  size_t sizeof_namespace_index(struct nvdimm_drvdata *ndd);
>>  int nd_label_active_count(struct nvdimm_drvdata *ndd);
>> -struct nd_namespace_label *nd_label_active(struct nvdimm_drvdata *ndd, int n);
>> +struct nd_lsa_label *nd_label_active(struct nvdimm_drvdata *ndd, int n);
>>  u32 nd_label_alloc_slot(struct nvdimm_drvdata *ndd);
>>  bool nd_label_free_slot(struct nvdimm_drvdata *ndd, u32 slot);
>>  u32 nd_label_nfree(struct nvdimm_drvdata *ndd);
>> diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
>> index 55cfbf1e0a95..bdf1ed6f23d8 100644
>> --- a/drivers/nvdimm/namespace_devs.c
>> +++ b/drivers/nvdimm/namespace_devs.c
>> @@ -1009,10 +1009,11 @@ static int namespace_update_uuid(struct nd_region *nd_region,
>>
>>  		mutex_lock(&nd_mapping->lock);
>>  		list_for_each_entry(label_ent, &nd_mapping->labels, list) {
>> -			struct nd_namespace_label *nd_label = label_ent->label;
>> +			struct nd_namespace_label *nd_label;
>>  			struct nd_label_id label_id;
>>  			uuid_t uuid;
>>
>> +			nd_label = &label_ent->label->ns_label;
>>  			if (!nd_label)
>>  				continue;
>>  			nsl_get_uuid(ndd, nd_label, &uuid);
>> @@ -1573,11 +1574,14 @@ static bool has_uuid_at_pos(struct nd_region *nd_region, const uuid_t *uuid,
>>  		bool found_uuid = false;
>>
>>  		list_for_each_entry(label_ent, &nd_mapping->labels, list) {
>> -			struct nd_namespace_label *nd_label = label_ent->label;
>> +			struct nd_lsa_label *lsa_label = label_ent->label;
>> +			struct nd_namespace_label *nd_label;
>>  			u16 position;
>>
>> -			if (!nd_label)
>> +			if (!lsa_label)
>>  				continue;
>> +
>> +			nd_label = &lsa_label->ns_label;
>>  			position = nsl_get_position(ndd, nd_label);
>>
>>  			if (!nsl_validate_isetcookie(ndd, nd_label, cookie))
>> @@ -1615,17 +1619,21 @@ static int select_pmem_id(struct nd_region *nd_region, const uuid_t *pmem_id)
>>  	for (i = 0; i < nd_region->ndr_mappings; i++) {
>>  		struct nd_mapping *nd_mapping = &nd_region->mapping[i];
>>  		struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
>> +		struct nd_lsa_label *lsa_label = NULL;
>>  		struct nd_namespace_label *nd_label = NULL;
>>  		u64 hw_start, hw_end, pmem_start, pmem_end;
>>  		struct nd_label_ent *label_ent;
>>
>>  		lockdep_assert_held(&nd_mapping->lock);
>>  		list_for_each_entry(label_ent, &nd_mapping->labels, list) {
>> -			nd_label = label_ent->label;
>> -			if (!nd_label)
>> +			lsa_label = label_ent->label;
>> +			if (!lsa_label)
>>  				continue;
>> +
>> +			nd_label = &lsa_label->ns_label;
>>  			if (nsl_uuid_equal(ndd, nd_label, pmem_id))
>>  				break;
>> +			lsa_label = NULL;
>>  			nd_label = NULL;
>>  		}
>>
>> @@ -1746,19 +1754,21 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
>>
>>  	/* Calculate total size and populate namespace properties from label0 */
>>  	for (i = 0; i < nd_region->ndr_mappings; i++) {
>> +		struct nd_lsa_label *lsa_label;
>>  		struct nd_namespace_label *label0;
>>  		struct nvdimm_drvdata *ndd;
>>
>>  		nd_mapping = &nd_region->mapping[i];
>>  		label_ent = list_first_entry_or_null(&nd_mapping->labels,
>>  				typeof(*label_ent), list);
>> -		label0 = label_ent ? label_ent->label : NULL;
>> +		lsa_label = label_ent ? label_ent->label : NULL;
>>
>> -		if (!label0) {
>> +		if (!lsa_label) {
>>  			WARN_ON(1);
>>  			continue;
>>  		}
>>
>> +		label0 = &lsa_label->ns_label;
>>  		ndd = to_ndd(nd_mapping);
>>  		size += nsl_get_rawsize(ndd, label0);
>>  		if (nsl_get_position(ndd, label0) != 0)
>> @@ -1943,12 +1953,15 @@ static struct device **scan_labels(struct nd_region *nd_region)
>>
>>  	/* "safe" because create_namespace_pmem() might list_move() label_ent */
>>  	list_for_each_entry_safe(label_ent, e, &nd_mapping->labels, list) {
>> -		struct nd_namespace_label *nd_label = label_ent->label;
>> +		struct nd_lsa_label *lsa_label = label_ent->label;
>> +		struct nd_namespace_label *nd_label;
>>  		struct device **__devs;
>>
>> -		if (!nd_label)
>> +		if (!lsa_label)
>>  			continue;
>>
>> +		nd_label = &lsa_label->ns_label;
>> +
>>  		/* skip labels that describe extents outside of the region */
>>  		if (nsl_get_dpa(ndd, nd_label) < nd_mapping->start ||
>>  		    nsl_get_dpa(ndd, nd_label) > map_end)
>> @@ -2122,7 +2135,7 @@ static int init_active_labels(struct nd_region *nd_region)
>>  		if (!count)
>>  			continue;
>>  		for (j = 0; j < count; j++) {
>> -			struct nd_namespace_label *label;
>> +			struct nd_lsa_label *label;
>>
>>  			label_ent = kzalloc(sizeof(*label_ent), GFP_KERNEL);
>>  			if (!label_ent)
>> diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
>> index 1cc06cc58d14..61348dee687d 100644
>> --- a/drivers/nvdimm/nd.h
>> +++ b/drivers/nvdimm/nd.h
>> @@ -376,7 +376,7 @@ enum nd_label_flags {
>>  struct nd_label_ent {
>>  	struct list_head list;
>>  	unsigned long flags;
>> -	struct nd_namespace_label *label;
>> +	struct nd_lsa_label *label;
>
>Looking at the series a bit more, I don't think creating 'struct nd_lsa_label' and making all the changes in this patch is necessary. I think an unamed union here of 'struct nd_namespace_label' and 'struct cxl_region_label' should be fine. Most of the CXL region handling should be quite different than namespace handling that the code paths will diverge. Adding a few helper functions should address some of the common code paths or creating separate cxl region based helpers to deal with the rest. i.e. slot_valid() can take a slot number rather than a label type. Being intentional in handling sepcific labeling may be better than trying to force a union between region and namespace labeling.
>
>>  };

Thanks for your suggestion Dave. Yes using unnamed union here will be
helpful. I will fix the change in next patch-set.


Regards,
Neeraj

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