drivers/nvdimm/pfn_devs.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright(c) 2013-2016 Intel Corporation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of version 2 of the GNU General Public License as
  * published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  */
 #include <linux/memremap.h>
 #include <linux/blkdev.h>
 #include <linux/device.h>
 #include <linux/genhd.h>
 #include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include "nd-core.h"
 #include "pfn.h"
 #include "nd.h"

 static void nd_pfn_release(struct device *dev)
 {
 	struct nd_region *nd_region = to_nd_region(dev->parent);
 	struct nd_pfn *nd_pfn = to_nd_pfn(dev);

 	dev_dbg(dev, "%s\n", __func__);
 	nd_detach_ndns(&nd_pfn->dev, &nd_pfn->ndns);
 	ida_simple_remove(&nd_region->pfn_ida, nd_pfn->id);
 	kfree(nd_pfn->uuid);
 	kfree(nd_pfn);
 }

 static struct device_type nd_pfn_device_type = {
 	.name = "nd_pfn",
 	.release = nd_pfn_release,
 };

 bool is_nd_pfn(struct device *dev)
 {
 	return dev ? dev->type == &nd_pfn_device_type : false;
 }
 EXPORT_SYMBOL(is_nd_pfn);

 struct nd_pfn *to_nd_pfn(struct device *dev)
 {
 	struct nd_pfn *nd_pfn = container_of(dev, struct nd_pfn, dev);

 	WARN_ON(!is_nd_pfn(dev));
 	return nd_pfn;
 }
 EXPORT_SYMBOL(to_nd_pfn);

 static ssize_t mode_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

 	switch (nd_pfn->mode) {
 	case PFN_MODE_RAM:
 		return sprintf(buf, "ram\n");
 	case PFN_MODE_PMEM:
 		return sprintf(buf, "pmem\n");
 	default:
 		return sprintf(buf, "none\n");
 	}
 }

 static ssize_t mode_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc = 0;

 	device_lock(dev);
 	nvdimm_bus_lock(dev);
 	if (dev->driver)
 		rc = -EBUSY;
 	else {
 		size_t n = len - 1;

 		if (strncmp(buf, "pmem\n", n) == 0
 				|| strncmp(buf, "pmem", n) == 0) {
 			nd_pfn->mode = PFN_MODE_PMEM;
 		} else if (strncmp(buf, "ram\n", n) == 0
 				|| strncmp(buf, "ram", n) == 0)
 			nd_pfn->mode = PFN_MODE_RAM;
 		else if (strncmp(buf, "none\n", n) == 0
 				|| strncmp(buf, "none", n) == 0)
 			nd_pfn->mode = PFN_MODE_NONE;
 		else
 			rc = -EINVAL;
 	}
 	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
 			rc, buf, buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
 	device_unlock(dev);

 	return rc ? rc : len;
 }
 static DEVICE_ATTR_RW(mode);

 static ssize_t align_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

 	return sprintf(buf, "%ld\n", nd_pfn->align);
 }

 static ssize_t __align_store(struct nd_pfn *nd_pfn, const char *buf)
 {
 	unsigned long val;
 	int rc;

 	rc = kstrtoul(buf, 0, &val);
 	if (rc)
 		return rc;

 	if (!is_power_of_2(val) || val < PAGE_SIZE || val > SZ_1G)
 		return -EINVAL;

 	if (nd_pfn->dev.driver)
 		return -EBUSY;
 	else
 		nd_pfn->align = val;

 	return 0;
 }

 static ssize_t align_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;

 	device_lock(dev);
 	nvdimm_bus_lock(dev);
 	rc = __align_store(nd_pfn, buf);
 	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
 			rc, buf, buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
 	device_unlock(dev);

 	return rc ? rc : len;
 }
 static DEVICE_ATTR_RW(align);

 static ssize_t uuid_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

 	if (nd_pfn->uuid)
 		return sprintf(buf, "%pUb\n", nd_pfn->uuid);
 	return sprintf(buf, "\n");
 }

 static ssize_t uuid_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;

 	device_lock(dev);
 	rc = nd_uuid_store(dev, &nd_pfn->uuid, buf, len);
 	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
 			rc, buf, buf[len - 1] == '\n' ? "" : "\n");
 	device_unlock(dev);

 	return rc ? rc : len;
 }
 static DEVICE_ATTR_RW(uuid);

 static ssize_t namespace_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;

 	nvdimm_bus_lock(dev);
 	rc = sprintf(buf, "%s\n", nd_pfn->ndns
 			? dev_name(&nd_pfn->ndns->dev) : "");
 	nvdimm_bus_unlock(dev);
 	return rc;
 }

 static ssize_t namespace_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;

 	device_lock(dev);
 	nvdimm_bus_lock(dev);
 	rc = nd_namespace_store(dev, &nd_pfn->ndns, buf, len);
 	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
 			rc, buf, buf[len - 1] == '\n' ? "" : "\n");
 	nvdimm_bus_unlock(dev);
 	device_unlock(dev);

 	return rc;
 }
 static DEVICE_ATTR_RW(namespace);

 static ssize_t resource_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;

 	device_lock(dev);
 	if (dev->driver) {
 		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
 		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
 		struct nd_namespace_common *ndns = nd_pfn->ndns;
 		u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
 		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

 		rc = sprintf(buf, "%#llx\n", (unsigned long long) nsio->res.start
 				+ start_pad + offset);
 	} else {
 		/* no address to convey if the pfn instance is disabled */
 		rc = -ENXIO;
 	}
 	device_unlock(dev);

 	return rc;
 }
 static DEVICE_ATTR_RO(resource);

 static ssize_t size_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
 	ssize_t rc;

 	device_lock(dev);
 	if (dev->driver) {
 		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
 		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
 		struct nd_namespace_common *ndns = nd_pfn->ndns;
 		u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
 		u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
 		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

 		rc = sprintf(buf, "%llu\n", (unsigned long long)
 				resource_size(&nsio->res) - start_pad
 				- end_trunc - offset);
 	} else {
 		/* no size to convey if the pfn instance is disabled */
 		rc = -ENXIO;
 	}
 	device_unlock(dev);

 	return rc;
 }
 static DEVICE_ATTR_RO(size);

 static struct attribute *nd_pfn_attributes[] = {
 	&dev_attr_mode.attr,
 	&dev_attr_namespace.attr,
 	&dev_attr_uuid.attr,
 	&dev_attr_align.attr,
 	&dev_attr_resource.attr,
 	&dev_attr_size.attr,
 	NULL,
 };

 static umode_t pfn_visible(struct kobject *kobj, struct attribute *a, int n)
 {
 	if (a == &dev_attr_resource.attr)
 		return 0400;
 	return a->mode;
 }

 struct attribute_group nd_pfn_attribute_group = {
 	.attrs = nd_pfn_attributes,
 	.is_visible = pfn_visible,
 };

 static const struct attribute_group *nd_pfn_attribute_groups[] = {
 	&nd_pfn_attribute_group,
 	&nd_device_attribute_group,
 	&nd_numa_attribute_group,
 	NULL,
 };

 struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
 		struct nd_namespace_common *ndns)
 {
 	struct device *dev = &nd_pfn->dev;

 	if (!nd_pfn)
 		return NULL;

 	nd_pfn->mode = PFN_MODE_NONE;
 	nd_pfn->align = HPAGE_SIZE;
 	dev = &nd_pfn->dev;
 	device_initialize(&nd_pfn->dev);
 	if (ndns && !__nd_attach_ndns(&nd_pfn->dev, ndns, &nd_pfn->ndns)) {
 		dev_dbg(&ndns->dev, "%s failed, already claimed by %s\n",
 				__func__, dev_name(ndns->claim));
 		put_device(dev);
 		return NULL;
 	}
 	return dev;
 }

 static struct nd_pfn *nd_pfn_alloc(struct nd_region *nd_region)
 {
 	struct nd_pfn *nd_pfn;
 	struct device *dev;

 	nd_pfn = kzalloc(sizeof(*nd_pfn), GFP_KERNEL);
 	if (!nd_pfn)
 		return NULL;

 	nd_pfn->id = ida_simple_get(&nd_region->pfn_ida, 0, 0, GFP_KERNEL);
 	if (nd_pfn->id < 0) {
 		kfree(nd_pfn);
 		return NULL;
 	}

 	dev = &nd_pfn->dev;
 	dev_set_name(dev, "pfn%d.%d", nd_region->id, nd_pfn->id);
 	dev->groups = nd_pfn_attribute_groups;
 	dev->type = &nd_pfn_device_type;
 	dev->parent = &nd_region->dev;

 	return nd_pfn;
 }

 struct device *nd_pfn_create(struct nd_region *nd_region)
 {
 	struct nd_pfn *nd_pfn;
 	struct device *dev;

 	if (!is_nd_pmem(&nd_region->dev))
 		return NULL;

 	nd_pfn = nd_pfn_alloc(nd_region);
 	dev = nd_pfn_devinit(nd_pfn, NULL);

 	__nd_device_register(dev);
 	return dev;
 }

 int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
 {
 	u64 checksum, offset;
 	enum nd_pfn_mode mode;
 	struct nd_namespace_io *nsio;
 	unsigned long align, start_pad;
 	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
 	struct nd_namespace_common *ndns = nd_pfn->ndns;
 	const u8 *parent_uuid = nd_dev_to_uuid(&ndns->dev);

 	if (!pfn_sb || !ndns)
 		return -ENODEV;

 	if (!is_nd_pmem(nd_pfn->dev.parent))
 		return -ENODEV;

 	if (nvdimm_read_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb)))
 		return -ENXIO;

 	if (memcmp(pfn_sb->signature, sig, PFN_SIG_LEN) != 0)
 		return -ENODEV;

 	checksum = le64_to_cpu(pfn_sb->checksum);
 	pfn_sb->checksum = 0;
 	if (checksum != nd_sb_checksum((struct nd_gen_sb *) pfn_sb))
 		return -ENODEV;
 	pfn_sb->checksum = cpu_to_le64(checksum);

 	if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0)
 		return -ENODEV;

 	if (__le16_to_cpu(pfn_sb->version_minor) < 1) {
 		pfn_sb->start_pad = 0;
 		pfn_sb->end_trunc = 0;
 	}

 	if (__le16_to_cpu(pfn_sb->version_minor) < 2)
 		pfn_sb->align = 0;

 	switch (le32_to_cpu(pfn_sb->mode)) {
 	case PFN_MODE_RAM:
 	case PFN_MODE_PMEM:
 		break;
 	default:
 		return -ENXIO;
 	}

 	align = le32_to_cpu(pfn_sb->align);
 	offset = le64_to_cpu(pfn_sb->dataoff);
 	start_pad = le32_to_cpu(pfn_sb->start_pad);
 	if (align == 0)
 		align = 1UL << ilog2(offset);
 	mode = le32_to_cpu(pfn_sb->mode);

 	if (!nd_pfn->uuid) {
 		/*
 		 * When probing a namepace via nd_pfn_probe() the uuid
 		 * is NULL (see: nd_pfn_devinit()) we init settings from
 		 * pfn_sb
 		 */
 		nd_pfn->uuid = kmemdup(pfn_sb->uuid, 16, GFP_KERNEL);
 		if (!nd_pfn->uuid)
 			return -ENOMEM;
 		nd_pfn->align = align;
 		nd_pfn->mode = mode;
 	} else {
 		/*
 		 * When probing a pfn / dax instance we validate the
 		 * live settings against the pfn_sb
 		 */
 		if (memcmp(nd_pfn->uuid, pfn_sb->uuid, 16) != 0)
 			return -ENODEV;

 		/*
 		 * If the uuid validates, but other settings mismatch
 		 * return EINVAL because userspace has managed to change
 		 * the configuration without specifying new
 		 * identification.
 		 */
 		if (nd_pfn->align != align || nd_pfn->mode != mode) {
 			dev_err(&nd_pfn->dev,
 					"init failed, settings mismatch\n");
 			dev_dbg(&nd_pfn->dev, "align: %lx:%lx mode: %d:%d\n",
 					nd_pfn->align, align, nd_pfn->mode,
 					mode);
 			return -EINVAL;
 		}
 	}

 	if (align > nvdimm_namespace_capacity(ndns)) {
 		dev_err(&nd_pfn->dev, "alignment: %lx exceeds capacity %llx\n",
 				align, nvdimm_namespace_capacity(ndns));
 		return -EINVAL;
 	}

 	/*
 	 * These warnings are verbose because they can only trigger in
 	 * the case where the physical address alignment of the
 	 * namespace has changed since the pfn superblock was
 	 * established.
 	 */
 	nsio = to_nd_namespace_io(&ndns->dev);
 	if (offset >= resource_size(&nsio->res)) {
 		dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
 				dev_name(&ndns->dev));
 		return -EBUSY;
 	}

 	if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
 			|| !IS_ALIGNED(offset, PAGE_SIZE)) {
 		dev_err(&nd_pfn->dev,
 				"bad offset: %#llx dax disabled align: %#lx\n",
 				offset, align);
 		return -ENXIO;
 	}

 	return 0;
 }
 EXPORT_SYMBOL(nd_pfn_validate);

 int nd_pfn_probe(struct device *dev, struct nd_namespace_common *ndns)
 {
 	int rc;
 	struct nd_pfn *nd_pfn;
 	struct device *pfn_dev;
 	struct nd_pfn_sb *pfn_sb;
 	struct nd_region *nd_region = to_nd_region(ndns->dev.parent);

 	if (ndns->force_raw)
 		return -ENODEV;

 	nvdimm_bus_lock(&ndns->dev);
 	nd_pfn = nd_pfn_alloc(nd_region);
 	pfn_dev = nd_pfn_devinit(nd_pfn, ndns);
 	nvdimm_bus_unlock(&ndns->dev);
 	if (!pfn_dev)
 		return -ENOMEM;
 	pfn_sb = devm_kzalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
 	nd_pfn = to_nd_pfn(pfn_dev);
 	nd_pfn->pfn_sb = pfn_sb;
 	rc = nd_pfn_validate(nd_pfn, PFN_SIG);
 	dev_dbg(dev, "%s: pfn: %s\n", __func__,
 			rc == 0 ? dev_name(pfn_dev) : "<none>");
 	if (rc < 0) {
 		__nd_detach_ndns(pfn_dev, &nd_pfn->ndns);
 		put_device(pfn_dev);
 	} else
 		__nd_device_register(pfn_dev);

 	return rc;
 }
 EXPORT_SYMBOL(nd_pfn_probe);

 /*
  * We hotplug memory at section granularity, pad the reserved area from
  * the previous section base to the namespace base address.
  */
 static unsigned long init_altmap_base(resource_size_t base)
 {
 	unsigned long base_pfn = PHYS_PFN(base);

 	return PFN_SECTION_ALIGN_DOWN(base_pfn);
 }

 static unsigned long init_altmap_reserve(resource_size_t base)
 {
 	unsigned long reserve = PHYS_PFN(SZ_8K);
 	unsigned long base_pfn = PHYS_PFN(base);

 	reserve += base_pfn - PFN_SECTION_ALIGN_DOWN(base_pfn);
 	return reserve;
 }

 static struct vmem_altmap *__nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
 		struct resource *res, struct vmem_altmap *altmap)
 {
 	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
 	u64 offset = le64_to_cpu(pfn_sb->dataoff);
 	u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
 	u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
 	struct nd_namespace_common *ndns = nd_pfn->ndns;
 	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
 	resource_size_t base = nsio->res.start + start_pad;
 	struct vmem_altmap __altmap = {
 		.base_pfn = init_altmap_base(base),
 		.reserve = init_altmap_reserve(base),
 	};

 	memcpy(res, &nsio->res, sizeof(*res));
 	res->start += start_pad;
 	res->end -= end_trunc;

 	if (nd_pfn->mode == PFN_MODE_RAM) {
 		if (offset < SZ_8K)
 			return ERR_PTR(-EINVAL);
 		nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
 		altmap = NULL;
 	} else if (nd_pfn->mode == PFN_MODE_PMEM) {
 		nd_pfn->npfns = PFN_SECTION_ALIGN_UP((resource_size(res)
 					- offset) / PAGE_SIZE);
 		if (le64_to_cpu(nd_pfn->pfn_sb->npfns) > nd_pfn->npfns)
 			dev_info(&nd_pfn->dev,
 					"number of pfns truncated from %lld to %ld\n",
 					le64_to_cpu(nd_pfn->pfn_sb->npfns),
 					nd_pfn->npfns);
 		memcpy(altmap, &__altmap, sizeof(*altmap));
 		altmap->free = PHYS_PFN(offset - SZ_8K);
 		altmap->alloc = 0;
 	} else
 		return ERR_PTR(-ENXIO);

 	return altmap;
 }

 static int nd_pfn_init(struct nd_pfn *nd_pfn)
 {
 	u32 dax_label_reserve = is_nd_dax(&nd_pfn->dev) ? SZ_128K : 0;
 	struct nd_namespace_common *ndns = nd_pfn->ndns;
 	u32 start_pad = 0, end_trunc = 0;
 	resource_size_t start, size;
 	struct nd_namespace_io *nsio;
 	struct nd_region *nd_region;
 	struct nd_pfn_sb *pfn_sb;
 	unsigned long npfns;
 	phys_addr_t offset;
 	const char *sig;
 	u64 checksum;
 	int rc;

 	pfn_sb = devm_kzalloc(&nd_pfn->dev, sizeof(*pfn_sb), GFP_KERNEL);
 	if (!pfn_sb)
 		return -ENOMEM;

 	nd_pfn->pfn_sb = pfn_sb;
 	if (is_nd_dax(&nd_pfn->dev))
 		sig = DAX_SIG;
 	else
 		sig = PFN_SIG;
 	rc = nd_pfn_validate(nd_pfn, sig);
 	if (rc != -ENODEV)
 		return rc;

 	/* no info block, do init */;
 	nd_region = to_nd_region(nd_pfn->dev.parent);
 	if (nd_region->ro) {
 		dev_info(&nd_pfn->dev,
 				"%s is read-only, unable to init metadata\n",
 				dev_name(&nd_region->dev));
 		return -ENXIO;
 	}

 	memset(pfn_sb, 0, sizeof(*pfn_sb));

 	/*
 	 * Check if pmem collides with 'System RAM' when section aligned and
 	 * trim it accordingly
 	 */
 	nsio = to_nd_namespace_io(&ndns->dev);
 	start = PHYS_SECTION_ALIGN_DOWN(nsio->res.start);
 	size = resource_size(&nsio->res);
 	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
 				IORES_DESC_NONE) == REGION_MIXED) {
 		start = nsio->res.start;
 		start_pad = PHYS_SECTION_ALIGN_UP(start) - start;
 	}

 	start = nsio->res.start;
 	size = PHYS_SECTION_ALIGN_UP(start + size) - start;
 	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
 				IORES_DESC_NONE) == REGION_MIXED) {
 		size = resource_size(&nsio->res);
 		end_trunc = start + size - PHYS_SECTION_ALIGN_DOWN(start + size);
 	}

 	if (start_pad + end_trunc)
 		dev_info(&nd_pfn->dev, "%s section collision, truncate %d bytes\n",
 				dev_name(&ndns->dev), start_pad + end_trunc);

 	/*
 	 * Note, we use 64 here for the standard size of struct page,
 	 * debugging options may cause it to be larger in which case the
 	 * implementation will limit the pfns advertised through
 	 * ->direct_access() to those that are included in the memmap.
 	 */
 	start += start_pad;
 	size = resource_size(&nsio->res);
 	npfns = PFN_SECTION_ALIGN_UP((size - start_pad - end_trunc - SZ_8K)
 			/ PAGE_SIZE);
 	if (nd_pfn->mode == PFN_MODE_PMEM) {
 		/*
 		 * vmemmap_populate_hugepages() allocates the memmap array in
 		 * HPAGE_SIZE chunks.
 		 */
 		offset = ALIGN(start + SZ_8K + 64 * npfns + dax_label_reserve,
 				max(nd_pfn->align, HPAGE_SIZE)) - start;
 	} else if (nd_pfn->mode == PFN_MODE_RAM)
 		offset = ALIGN(start + SZ_8K + dax_label_reserve,
 				nd_pfn->align) - start;
 	else
 		return -ENXIO;

 	if (offset + start_pad + end_trunc >= size) {
 		dev_err(&nd_pfn->dev, "%s unable to satisfy requested alignment\n",
 				dev_name(&ndns->dev));
 		return -ENXIO;
 	}

 	npfns = (size - offset - start_pad - end_trunc) / SZ_4K;
 	pfn_sb->mode = cpu_to_le32(nd_pfn->mode);
 	pfn_sb->dataoff = cpu_to_le64(offset);
 	pfn_sb->npfns = cpu_to_le64(npfns);
 	memcpy(pfn_sb->signature, sig, PFN_SIG_LEN);
 	memcpy(pfn_sb->uuid, nd_pfn->uuid, 16);
 	memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16);
 	pfn_sb->version_major = cpu_to_le16(1);
 	pfn_sb->version_minor = cpu_to_le16(2);
 	pfn_sb->start_pad = cpu_to_le32(start_pad);
 	pfn_sb->end_trunc = cpu_to_le32(end_trunc);
 	pfn_sb->align = cpu_to_le32(nd_pfn->align);
 	checksum = nd_sb_checksum((struct nd_gen_sb *) pfn_sb);
 	pfn_sb->checksum = cpu_to_le64(checksum);

 	return nvdimm_write_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb));
 }

 /*
  * Determine the effective resource range and vmem_altmap from an nd_pfn
  * instance.
  */
 struct vmem_altmap *nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
 		struct resource *res, struct vmem_altmap *altmap)
 {
 	int rc;

 	if (!nd_pfn->uuid || !nd_pfn->ndns)
 		return ERR_PTR(-ENODEV);

 	rc = nd_pfn_init(nd_pfn);
 	if (rc)
 		return ERR_PTR(rc);

 	/* we need a valid pfn_sb before we can init a vmem_altmap */
 	return __nvdimm_setup_pfn(nd_pfn, res, altmap);
 }
 EXPORT_SYMBOL_GPL(nvdimm_setup_pfn);
	/*
	* Copyright(c) 2013-2016 Intel Corporation. All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of version 2 of the GNU General Public License as
	* published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*/
	#include <linux/memremap.h>
	#include <linux/blkdev.h>
	#include <linux/device.h>
	#include <linux/genhd.h>
	#include <linux/sizes.h>
	#include <linux/slab.h>
	#include <linux/fs.h>
	#include <linux/mm.h>
	#include "nd-core.h"
	#include "pfn.h"
	#include "nd.h"

	static void nd_pfn_release(struct device *dev)
	{
	struct nd_region *nd_region = to_nd_region(dev->parent);
	struct nd_pfn *nd_pfn = to_nd_pfn(dev);

	dev_dbg(dev, "%s\n", __func__);
	nd_detach_ndns(&nd_pfn->dev, &nd_pfn->ndns);
	ida_simple_remove(&nd_region->pfn_ida, nd_pfn->id);
	kfree(nd_pfn->uuid);
	kfree(nd_pfn);
	}

	static struct device_type nd_pfn_device_type = {
	.name = "nd_pfn",
	.release = nd_pfn_release,
	};

	bool is_nd_pfn(struct device *dev)
	{
	return dev ? dev->type == &nd_pfn_device_type : false;
	}
	EXPORT_SYMBOL(is_nd_pfn);

	struct nd_pfn to_nd_pfn(struct device dev)
	{
	struct nd_pfn *nd_pfn = container_of(dev, struct nd_pfn, dev);

	WARN_ON(!is_nd_pfn(dev));
	return nd_pfn;
	}
	EXPORT_SYMBOL(to_nd_pfn);

	static ssize_t mode_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

	switch (nd_pfn->mode) {
	case PFN_MODE_RAM:
	return sprintf(buf, "ram\n");
	case PFN_MODE_PMEM:
	return sprintf(buf, "pmem\n");
	default:
	return sprintf(buf, "none\n");
	}
	}

	static ssize_t mode_store(struct device *dev,
	struct device_attribute attr, const char buf, size_t len)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
	ssize_t rc = 0;

	device_lock(dev);
	nvdimm_bus_lock(dev);
	if (dev->driver)
	rc = -EBUSY;
	else {
	size_t n = len - 1;

	if (strncmp(buf, "pmem\n", n) == 0
	\|\| strncmp(buf, "pmem", n) == 0) {
	nd_pfn->mode = PFN_MODE_PMEM;
	} else if (strncmp(buf, "ram\n", n) == 0
	\|\| strncmp(buf, "ram", n) == 0)
	nd_pfn->mode = PFN_MODE_RAM;
	else if (strncmp(buf, "none\n", n) == 0
	\|\| strncmp(buf, "none", n) == 0)
	nd_pfn->mode = PFN_MODE_NONE;
	else
	rc = -EINVAL;
	}
	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
	rc, buf, buf[len - 1] == '\n' ? "" : "\n");
	nvdimm_bus_unlock(dev);
	device_unlock(dev);

	return rc ? rc : len;
	}
	static DEVICE_ATTR_RW(mode);

	static ssize_t align_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

	return sprintf(buf, "%ld\n", nd_pfn->align);
	}

	static ssize_t __align_store(struct nd_pfn nd_pfn, const char buf)
	{
	unsigned long val;
	int rc;

	rc = kstrtoul(buf, 0, &val);
	if (rc)
	return rc;

	if (!is_power_of_2(val) \|\| val < PAGE_SIZE \|\| val > SZ_1G)
	return -EINVAL;

	if (nd_pfn->dev.driver)
	return -EBUSY;
	else
	nd_pfn->align = val;

	return 0;
	}

	static ssize_t align_store(struct device *dev,
	struct device_attribute attr, const char buf, size_t len)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
	ssize_t rc;

	device_lock(dev);
	nvdimm_bus_lock(dev);
	rc = __align_store(nd_pfn, buf);
	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
	rc, buf, buf[len - 1] == '\n' ? "" : "\n");
	nvdimm_bus_unlock(dev);
	device_unlock(dev);

	return rc ? rc : len;
	}
	static DEVICE_ATTR_RW(align);

	static ssize_t uuid_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

	if (nd_pfn->uuid)
	return sprintf(buf, "%pUb\n", nd_pfn->uuid);
	return sprintf(buf, "\n");
	}

	static ssize_t uuid_store(struct device *dev,
	struct device_attribute attr, const char buf, size_t len)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
	ssize_t rc;

	device_lock(dev);
	rc = nd_uuid_store(dev, &nd_pfn->uuid, buf, len);
	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
	rc, buf, buf[len - 1] == '\n' ? "" : "\n");
	device_unlock(dev);

	return rc ? rc : len;
	}
	static DEVICE_ATTR_RW(uuid);

	static ssize_t namespace_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
	ssize_t rc;

	nvdimm_bus_lock(dev);
	rc = sprintf(buf, "%s\n", nd_pfn->ndns
	? dev_name(&nd_pfn->ndns->dev) : "");
	nvdimm_bus_unlock(dev);
	return rc;
	}

	static ssize_t namespace_store(struct device *dev,
	struct device_attribute attr, const char buf, size_t len)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
	ssize_t rc;

	device_lock(dev);
	nvdimm_bus_lock(dev);
	rc = nd_namespace_store(dev, &nd_pfn->ndns, buf, len);
	dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
	rc, buf, buf[len - 1] == '\n' ? "" : "\n");
	nvdimm_bus_unlock(dev);
	device_unlock(dev);

	return rc;
	}
	static DEVICE_ATTR_RW(namespace);

	static ssize_t resource_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
	ssize_t rc;

	device_lock(dev);
	if (dev->driver) {
	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
	u64 offset = __le64_to_cpu(pfn_sb->dataoff);
	struct nd_namespace_common *ndns = nd_pfn->ndns;
	u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

	rc = sprintf(buf, "%#llx\n", (unsigned long long) nsio->res.start
	+ start_pad + offset);
	} else {
	/* no address to convey if the pfn instance is disabled */
	rc = -ENXIO;
	}
	device_unlock(dev);

	return rc;
	}
	static DEVICE_ATTR_RO(resource);

	static ssize_t size_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
	ssize_t rc;

	device_lock(dev);
	if (dev->driver) {
	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
	u64 offset = __le64_to_cpu(pfn_sb->dataoff);
	struct nd_namespace_common *ndns = nd_pfn->ndns;
	u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
	u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

	rc = sprintf(buf, "%llu\n", (unsigned long long)
	resource_size(&nsio->res) - start_pad
	- end_trunc - offset);
	} else {
	/* no size to convey if the pfn instance is disabled */
	rc = -ENXIO;
	}
	device_unlock(dev);

	return rc;
	}
	static DEVICE_ATTR_RO(size);

	static struct attribute *nd_pfn_attributes[] = {
	&dev_attr_mode.attr,
	&dev_attr_namespace.attr,
	&dev_attr_uuid.attr,
	&dev_attr_align.attr,
	&dev_attr_resource.attr,
	&dev_attr_size.attr,
	NULL,
	};

	static umode_t pfn_visible(struct kobject kobj, struct attribute a, int n)
	{
	if (a == &dev_attr_resource.attr)
	return 0400;
	return a->mode;
	}

	struct attribute_group nd_pfn_attribute_group = {
	.attrs = nd_pfn_attributes,
	.is_visible = pfn_visible,
	};

	static const struct attribute_group *nd_pfn_attribute_groups[] = {
	&nd_pfn_attribute_group,
	&nd_device_attribute_group,
	&nd_numa_attribute_group,
	NULL,
	};

	struct device nd_pfn_devinit(struct nd_pfn nd_pfn,
	struct nd_namespace_common *ndns)
	{
	struct device *dev = &nd_pfn->dev;

	if (!nd_pfn)
	return NULL;

	nd_pfn->mode = PFN_MODE_NONE;
	nd_pfn->align = HPAGE_SIZE;
	dev = &nd_pfn->dev;
	device_initialize(&nd_pfn->dev);
	if (ndns && !__nd_attach_ndns(&nd_pfn->dev, ndns, &nd_pfn->ndns)) {
	dev_dbg(&ndns->dev, "%s failed, already claimed by %s\n",
	__func__, dev_name(ndns->claim));
	put_device(dev);
	return NULL;
	}
	return dev;
	}

	static struct nd_pfn nd_pfn_alloc(struct nd_region nd_region)
	{
	struct nd_pfn *nd_pfn;
	struct device *dev;

	nd_pfn = kzalloc(sizeof(*nd_pfn), GFP_KERNEL);
	if (!nd_pfn)
	return NULL;

	nd_pfn->id = ida_simple_get(&nd_region->pfn_ida, 0, 0, GFP_KERNEL);
	if (nd_pfn->id < 0) {
	kfree(nd_pfn);
	return NULL;
	}

	dev = &nd_pfn->dev;
	dev_set_name(dev, "pfn%d.%d", nd_region->id, nd_pfn->id);
	dev->groups = nd_pfn_attribute_groups;
	dev->type = &nd_pfn_device_type;
	dev->parent = &nd_region->dev;

	return nd_pfn;
	}

	struct device nd_pfn_create(struct nd_region nd_region)
	{
	struct nd_pfn *nd_pfn;
	struct device *dev;

	if (!is_nd_pmem(&nd_region->dev))
	return NULL;

	nd_pfn = nd_pfn_alloc(nd_region);
	dev = nd_pfn_devinit(nd_pfn, NULL);

	__nd_device_register(dev);
	return dev;
	}

	int nd_pfn_validate(struct nd_pfn nd_pfn, const char sig)
	{
	u64 checksum, offset;
	enum nd_pfn_mode mode;
	struct nd_namespace_io *nsio;
	unsigned long align, start_pad;
	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
	struct nd_namespace_common *ndns = nd_pfn->ndns;
	const u8 *parent_uuid = nd_dev_to_uuid(&ndns->dev);

	if (!pfn_sb \|\| !ndns)
	return -ENODEV;

	if (!is_nd_pmem(nd_pfn->dev.parent))
	return -ENODEV;

	if (nvdimm_read_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb)))
	return -ENXIO;

	if (memcmp(pfn_sb->signature, sig, PFN_SIG_LEN) != 0)
	return -ENODEV;

	checksum = le64_to_cpu(pfn_sb->checksum);
	pfn_sb->checksum = 0;
	if (checksum != nd_sb_checksum((struct nd_gen_sb *) pfn_sb))
	return -ENODEV;
	pfn_sb->checksum = cpu_to_le64(checksum);

	if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0)
	return -ENODEV;

	if (__le16_to_cpu(pfn_sb->version_minor) < 1) {
	pfn_sb->start_pad = 0;
	pfn_sb->end_trunc = 0;
	}

	if (__le16_to_cpu(pfn_sb->version_minor) < 2)
	pfn_sb->align = 0;

	switch (le32_to_cpu(pfn_sb->mode)) {
	case PFN_MODE_RAM:
	case PFN_MODE_PMEM:
	break;
	default:
	return -ENXIO;
	}

	align = le32_to_cpu(pfn_sb->align);
	offset = le64_to_cpu(pfn_sb->dataoff);
	start_pad = le32_to_cpu(pfn_sb->start_pad);
	if (align == 0)
	align = 1UL << ilog2(offset);
	mode = le32_to_cpu(pfn_sb->mode);

	if (!nd_pfn->uuid) {
	/*
	* When probing a namepace via nd_pfn_probe() the uuid
	* is NULL (see: nd_pfn_devinit()) we init settings from
	* pfn_sb
	*/
	nd_pfn->uuid = kmemdup(pfn_sb->uuid, 16, GFP_KERNEL);
	if (!nd_pfn->uuid)
	return -ENOMEM;
	nd_pfn->align = align;
	nd_pfn->mode = mode;
	} else {
	/*
	* When probing a pfn / dax instance we validate the
	* live settings against the pfn_sb
	*/
	if (memcmp(nd_pfn->uuid, pfn_sb->uuid, 16) != 0)
	return -ENODEV;

	/*
	* If the uuid validates, but other settings mismatch
	* return EINVAL because userspace has managed to change
	* the configuration without specifying new
	* identification.
	*/
	if (nd_pfn->align != align \|\| nd_pfn->mode != mode) {
	dev_err(&nd_pfn->dev,
	"init failed, settings mismatch\n");
	dev_dbg(&nd_pfn->dev, "align: %lx:%lx mode: %d:%d\n",
	nd_pfn->align, align, nd_pfn->mode,
	mode);
	return -EINVAL;
	}
	}

	if (align > nvdimm_namespace_capacity(ndns)) {
	dev_err(&nd_pfn->dev, "alignment: %lx exceeds capacity %llx\n",
	align, nvdimm_namespace_capacity(ndns));
	return -EINVAL;
	}

	/*
	* These warnings are verbose because they can only trigger in
	* the case where the physical address alignment of the
	* namespace has changed since the pfn superblock was
	* established.
	*/
	nsio = to_nd_namespace_io(&ndns->dev);
	if (offset >= resource_size(&nsio->res)) {
	dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
	dev_name(&ndns->dev));
	return -EBUSY;
	}

	if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
	\|\| !IS_ALIGNED(offset, PAGE_SIZE)) {
	dev_err(&nd_pfn->dev,
	"bad offset: %#llx dax disabled align: %#lx\n",
	offset, align);
	return -ENXIO;
	}

	return 0;
	}
	EXPORT_SYMBOL(nd_pfn_validate);

	int nd_pfn_probe(struct device dev, struct nd_namespace_common ndns)
	{
	int rc;
	struct nd_pfn *nd_pfn;
	struct device *pfn_dev;
	struct nd_pfn_sb *pfn_sb;
	struct nd_region *nd_region = to_nd_region(ndns->dev.parent);

	if (ndns->force_raw)
	return -ENODEV;

	nvdimm_bus_lock(&ndns->dev);
	nd_pfn = nd_pfn_alloc(nd_region);
	pfn_dev = nd_pfn_devinit(nd_pfn, ndns);
	nvdimm_bus_unlock(&ndns->dev);
	if (!pfn_dev)
	return -ENOMEM;
	pfn_sb = devm_kzalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
	nd_pfn = to_nd_pfn(pfn_dev);
	nd_pfn->pfn_sb = pfn_sb;
	rc = nd_pfn_validate(nd_pfn, PFN_SIG);
	dev_dbg(dev, "%s: pfn: %s\n", __func__,
	rc == 0 ? dev_name(pfn_dev) : "<none>");
	if (rc < 0) {
	__nd_detach_ndns(pfn_dev, &nd_pfn->ndns);
	put_device(pfn_dev);
	} else
	__nd_device_register(pfn_dev);

	return rc;
	}
	EXPORT_SYMBOL(nd_pfn_probe);

	/*
	* We hotplug memory at section granularity, pad the reserved area from
	* the previous section base to the namespace base address.
	*/
	static unsigned long init_altmap_base(resource_size_t base)
	{
	unsigned long base_pfn = PHYS_PFN(base);

	return PFN_SECTION_ALIGN_DOWN(base_pfn);
	}

	static unsigned long init_altmap_reserve(resource_size_t base)
	{
	unsigned long reserve = PHYS_PFN(SZ_8K);
	unsigned long base_pfn = PHYS_PFN(base);

	reserve += base_pfn - PFN_SECTION_ALIGN_DOWN(base_pfn);
	return reserve;
	}

	static struct vmem_altmap __nvdimm_setup_pfn(struct nd_pfn nd_pfn,
	struct resource res, struct vmem_altmap altmap)
	{
	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
	u64 offset = le64_to_cpu(pfn_sb->dataoff);
	u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
	u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
	struct nd_namespace_common *ndns = nd_pfn->ndns;
	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
	resource_size_t base = nsio->res.start + start_pad;
	struct vmem_altmap __altmap = {
	.base_pfn = init_altmap_base(base),
	.reserve = init_altmap_reserve(base),
	};

	memcpy(res, &nsio->res, sizeof(*res));
	res->start += start_pad;
	res->end -= end_trunc;

	if (nd_pfn->mode == PFN_MODE_RAM) {
	if (offset < SZ_8K)
	return ERR_PTR(-EINVAL);
	nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
	altmap = NULL;
	} else if (nd_pfn->mode == PFN_MODE_PMEM) {
	nd_pfn->npfns = PFN_SECTION_ALIGN_UP((resource_size(res)
	- offset) / PAGE_SIZE);
	if (le64_to_cpu(nd_pfn->pfn_sb->npfns) > nd_pfn->npfns)
	dev_info(&nd_pfn->dev,
	"number of pfns truncated from %lld to %ld\n",
	le64_to_cpu(nd_pfn->pfn_sb->npfns),
	nd_pfn->npfns);
	memcpy(altmap, &__altmap, sizeof(*altmap));
	altmap->free = PHYS_PFN(offset - SZ_8K);
	altmap->alloc = 0;
	} else
	return ERR_PTR(-ENXIO);

	return altmap;
	}

	static int nd_pfn_init(struct nd_pfn *nd_pfn)
	{
	u32 dax_label_reserve = is_nd_dax(&nd_pfn->dev) ? SZ_128K : 0;
	struct nd_namespace_common *ndns = nd_pfn->ndns;
	u32 start_pad = 0, end_trunc = 0;
	resource_size_t start, size;
	struct nd_namespace_io *nsio;
	struct nd_region *nd_region;
	struct nd_pfn_sb *pfn_sb;
	unsigned long npfns;
	phys_addr_t offset;
	const char *sig;
	u64 checksum;
	int rc;

	pfn_sb = devm_kzalloc(&nd_pfn->dev, sizeof(*pfn_sb), GFP_KERNEL);
	if (!pfn_sb)
	return -ENOMEM;

	nd_pfn->pfn_sb = pfn_sb;
	if (is_nd_dax(&nd_pfn->dev))
	sig = DAX_SIG;
	else
	sig = PFN_SIG;
	rc = nd_pfn_validate(nd_pfn, sig);
	if (rc != -ENODEV)
	return rc;

	/* no info block, do init */;
	nd_region = to_nd_region(nd_pfn->dev.parent);
	if (nd_region->ro) {
	dev_info(&nd_pfn->dev,
	"%s is read-only, unable to init metadata\n",
	dev_name(&nd_region->dev));
	return -ENXIO;
	}

	memset(pfn_sb, 0, sizeof(*pfn_sb));

	/*
	* Check if pmem collides with 'System RAM' when section aligned and
	* trim it accordingly
	*/
	nsio = to_nd_namespace_io(&ndns->dev);
	start = PHYS_SECTION_ALIGN_DOWN(nsio->res.start);
	size = resource_size(&nsio->res);
	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
	IORES_DESC_NONE) == REGION_MIXED) {
	start = nsio->res.start;
	start_pad = PHYS_SECTION_ALIGN_UP(start) - start;
	}

	start = nsio->res.start;
	size = PHYS_SECTION_ALIGN_UP(start + size) - start;
	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
	IORES_DESC_NONE) == REGION_MIXED) {
	size = resource_size(&nsio->res);
	end_trunc = start + size - PHYS_SECTION_ALIGN_DOWN(start + size);
	}

	if (start_pad + end_trunc)
	dev_info(&nd_pfn->dev, "%s section collision, truncate %d bytes\n",
	dev_name(&ndns->dev), start_pad + end_trunc);

	/*
	* Note, we use 64 here for the standard size of struct page,
	* debugging options may cause it to be larger in which case the
	* implementation will limit the pfns advertised through
	* ->direct_access() to those that are included in the memmap.
	*/
	start += start_pad;
	size = resource_size(&nsio->res);
	npfns = PFN_SECTION_ALIGN_UP((size - start_pad - end_trunc - SZ_8K)
	/ PAGE_SIZE);
	if (nd_pfn->mode == PFN_MODE_PMEM) {
	/*
	* vmemmap_populate_hugepages() allocates the memmap array in
	* HPAGE_SIZE chunks.
	*/
	offset = ALIGN(start + SZ_8K + 64 * npfns + dax_label_reserve,
	max(nd_pfn->align, HPAGE_SIZE)) - start;
	} else if (nd_pfn->mode == PFN_MODE_RAM)
	offset = ALIGN(start + SZ_8K + dax_label_reserve,
	nd_pfn->align) - start;
	else
	return -ENXIO;

	if (offset + start_pad + end_trunc >= size) {
	dev_err(&nd_pfn->dev, "%s unable to satisfy requested alignment\n",
	dev_name(&ndns->dev));
	return -ENXIO;
	}

	npfns = (size - offset - start_pad - end_trunc) / SZ_4K;
	pfn_sb->mode = cpu_to_le32(nd_pfn->mode);
	pfn_sb->dataoff = cpu_to_le64(offset);
	pfn_sb->npfns = cpu_to_le64(npfns);
	memcpy(pfn_sb->signature, sig, PFN_SIG_LEN);
	memcpy(pfn_sb->uuid, nd_pfn->uuid, 16);
	memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16);
	pfn_sb->version_major = cpu_to_le16(1);
	pfn_sb->version_minor = cpu_to_le16(2);
	pfn_sb->start_pad = cpu_to_le32(start_pad);
	pfn_sb->end_trunc = cpu_to_le32(end_trunc);
	pfn_sb->align = cpu_to_le32(nd_pfn->align);
	checksum = nd_sb_checksum((struct nd_gen_sb *) pfn_sb);
	pfn_sb->checksum = cpu_to_le64(checksum);

	return nvdimm_write_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb));
	}

	/*
	* Determine the effective resource range and vmem_altmap from an nd_pfn
	* instance.
	*/
	struct vmem_altmap nvdimm_setup_pfn(struct nd_pfn nd_pfn,
	struct resource res, struct vmem_altmap altmap)
	{
	int rc;

	if (!nd_pfn->uuid \|\| !nd_pfn->ndns)
	return ERR_PTR(-ENODEV);

	rc = nd_pfn_init(nd_pfn);
	if (rc)
	return ERR_PTR(rc);

	/* we need a valid pfn_sb before we can init a vmem_altmap */
	return __nvdimm_setup_pfn(nd_pfn, res, altmap);
	}
	EXPORT_SYMBOL_GPL(nvdimm_setup_pfn);