memremap: change devm_memremap_pages interface to use struct dev_pagemap

This new interface is similar to how struct device (and many others)
work. The caller initializes a 'struct dev_pagemap' as required
and calls 'devm_memremap_pages'. This allows the pagemap structure to
be embedded in another structure and thus container_of can be used. In
this way application specific members can be stored in a containing
struct.

This will be used by the P2P infrastructure and HMM could probably
be cleaned up to use it as well (instead of having it's own, similar
'hmm_devmem_pages_create' function).

Signed-off-by: Logan Gunthorpe <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Dan Williams <[e-mail]>

drivers/dax/pmem.c

···
 struct dax_pmem {
 	struct device *dev;
 	struct percpu_ref ref;
+	struct dev_pagemap pgmap;
 	struct completion cmp;
 };
 
···
 	struct nd_namespace_common *ndns;
 	struct nd_dax *nd_dax = to_nd_dax(dev);
 	struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
-	struct vmem_altmap __altmap, *altmap = NULL;
 
 	ndns = nvdimm_namespace_common_probe(dev);
 	if (IS_ERR(ndns))
 		return PTR_ERR(ndns);
 	nsio = to_nd_namespace_io(&ndns->dev);
 
+	dax_pmem = devm_kzalloc(dev, sizeof(*dax_pmem), GFP_KERNEL);
+	if (!dax_pmem)
+		return -ENOMEM;
+
 	/* parse the 'pfn' info block via ->rw_bytes */
 	rc = devm_nsio_enable(dev, nsio);
 	if (rc)
 		return rc;
-	altmap = nvdimm_setup_pfn(nd_pfn, &res, &__altmap);
-	if (IS_ERR(altmap))
-		return PTR_ERR(altmap);
+	rc = nvdimm_setup_pfn(nd_pfn, &dax_pmem->pgmap);
+	if (rc)
+		return rc;
 	devm_nsio_disable(dev, nsio);
 
 	pfn_sb = nd_pfn->pfn_sb;
···
 		dev_warn(dev, "could not reserve region %pR\n", &nsio->res);
 		return -EBUSY;
 	}
-
-	dax_pmem = devm_kzalloc(dev, sizeof(*dax_pmem), GFP_KERNEL);
-	if (!dax_pmem)
-		return -ENOMEM;
 
 	dax_pmem->dev = dev;
 	init_completion(&dax_pmem->cmp);
···
 	if (rc)
 		return rc;
 
-	addr = devm_memremap_pages(dev, &res, &dax_pmem->ref, altmap);
+	dax_pmem->pgmap.ref = &dax_pmem->ref;
+	addr = devm_memremap_pages(dev, &dax_pmem->pgmap);
 	if (IS_ERR(addr))
 		return PTR_ERR(addr);
 
···
 		return rc;
 
 	/* adjust the dax_region resource to the start of data */
+	memcpy(&res, &dax_pmem->pgmap.res, sizeof(res));
 	res.start += le64_to_cpu(pfn_sb->dataoff);
 
 	rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", &region_id, &id);

drivers/nvdimm/nd.h

···
 void nvdimm_badblocks_populate(struct nd_region *nd_region,
 		struct badblocks *bb, const struct resource *res);
 #if IS_ENABLED(CONFIG_ND_CLAIM)
-struct vmem_altmap *nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
-		struct resource *res, struct vmem_altmap *altmap);
+int nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap);
 int devm_nsio_enable(struct device *dev, struct nd_namespace_io *nsio);
 void devm_nsio_disable(struct device *dev, struct nd_namespace_io *nsio);
 #else
-static inline struct vmem_altmap *nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
-		struct resource *res, struct vmem_altmap *altmap)
+static inline int nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
+				   struct dev_pagemap *pgmap)
 {
-	return ERR_PTR(-ENXIO);
+	return -ENXIO;
 }
 static inline int devm_nsio_enable(struct device *dev,
 		struct nd_namespace_io *nsio)

drivers/nvdimm/pfn_devs.c

···
 	return reserve;
 }
 
-static struct vmem_altmap *__nvdimm_setup_pfn(struct nd_pfn *nd_pfn,
-		struct resource *res, struct vmem_altmap *altmap)
+static int __nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
 {
+	struct resource *res = &pgmap->res;
+	struct vmem_altmap *altmap = &pgmap->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);
···
 	res->start += start_pad;
 	res->end -= end_trunc;
 
+	pgmap->type = MEMORY_DEVICE_HOST;
+
 	if (nd_pfn->mode == PFN_MODE_RAM) {
 		if (offset < SZ_8K)
-			return ERR_PTR(-EINVAL);
+			return -EINVAL;
 		nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
-		altmap = NULL;
+		pgmap->altmap_valid = false;
 	} else if (nd_pfn->mode == PFN_MODE_PMEM) {
 		nd_pfn->npfns = PFN_SECTION_ALIGN_UP((resource_size(res)
 					- offset) / PAGE_SIZE);
···
 		memcpy(altmap, &__altmap, sizeof(*altmap));
 		altmap->free = PHYS_PFN(offset - SZ_8K);
 		altmap->alloc = 0;
+		pgmap->altmap_valid = true;
 	} else
-		return ERR_PTR(-ENXIO);
+		return -ENXIO;
 
-	return altmap;
+	return 0;
 }
 
 static u64 phys_pmem_align_down(struct nd_pfn *nd_pfn, u64 phys)
···
  * 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 nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
 {
 	int rc;
 
 	if (!nd_pfn->uuid || !nd_pfn->ndns)
-		return ERR_PTR(-ENODEV);
+		return -ENODEV;
 
 	rc = nd_pfn_init(nd_pfn);
 	if (rc)
-		return ERR_PTR(rc);
+		return rc;
 
-	/* we need a valid pfn_sb before we can init a vmem_altmap */
-	return __nvdimm_setup_pfn(nd_pfn, res, altmap);
+	/* we need a valid pfn_sb before we can init a dev_pagemap */
+	return __nvdimm_setup_pfn(nd_pfn, pgmap);
 }
 EXPORT_SYMBOL_GPL(nvdimm_setup_pfn);

drivers/nvdimm/pmem.c

···
 {
 	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
 	struct nd_region *nd_region = to_nd_region(dev->parent);
-	struct vmem_altmap __altmap, *altmap = NULL;
 	int nid = dev_to_node(dev), fua, wbc;
 	struct resource *res = &nsio->res;
+	struct resource bb_res;
 	struct nd_pfn *nd_pfn = NULL;
 	struct dax_device *dax_dev;
 	struct nd_pfn_sb *pfn_sb;
 	struct pmem_device *pmem;
-	struct resource pfn_res;
 	struct request_queue *q;
 	struct device *gendev;
 	struct gendisk *disk;
 	void *addr;
-
-	/* while nsio_rw_bytes is active, parse a pfn info block if present */
-	if (is_nd_pfn(dev)) {
-		nd_pfn = to_nd_pfn(dev);
-		altmap = nvdimm_setup_pfn(nd_pfn, &pfn_res, &__altmap);
-		if (IS_ERR(altmap))
-			return PTR_ERR(altmap);
-	}
-
-	/* we're attaching a block device, disable raw namespace access */
-	devm_nsio_disable(dev, nsio);
+	int rc;
 
 	pmem = devm_kzalloc(dev, sizeof(*pmem), GFP_KERNEL);
 	if (!pmem)
 		return -ENOMEM;
+
+	/* while nsio_rw_bytes is active, parse a pfn info block if present */
+	if (is_nd_pfn(dev)) {
+		nd_pfn = to_nd_pfn(dev);
+		rc = nvdimm_setup_pfn(nd_pfn, &pmem->pgmap);
+		if (rc)
+			return rc;
+	}
+
+	/* we're attaching a block device, disable raw namespace access */
+	devm_nsio_disable(dev, nsio);
 
 	dev_set_drvdata(dev, pmem);
 	pmem->phys_addr = res->start;
···
 		return -ENOMEM;
 
 	pmem->pfn_flags = PFN_DEV;
+	pmem->pgmap.ref = &q->q_usage_counter;
 	if (is_nd_pfn(dev)) {
-		addr = devm_memremap_pages(dev, &pfn_res, &q->q_usage_counter,
-				altmap);
+		addr = devm_memremap_pages(dev, &pmem->pgmap);
 		pfn_sb = nd_pfn->pfn_sb;
 		pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);
-		pmem->pfn_pad = resource_size(res) - resource_size(&pfn_res);
+		pmem->pfn_pad = resource_size(res) -
+			resource_size(&pmem->pgmap.res);
 		pmem->pfn_flags |= PFN_MAP;
-		res = &pfn_res; /* for badblocks populate */
-		res->start += pmem->data_offset;
+		memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));
+		bb_res.start += pmem->data_offset;
 	} else if (pmem_should_map_pages(dev)) {
-		addr = devm_memremap_pages(dev, &nsio->res,
-				&q->q_usage_counter, NULL);
+		memcpy(&pmem->pgmap.res, &nsio->res, sizeof(pmem->pgmap.res));
+		pmem->pgmap.altmap_valid = false;
+		addr = devm_memremap_pages(dev, &pmem->pgmap);
 		pmem->pfn_flags |= PFN_MAP;
+		memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));
 	} else
 		addr = devm_memremap(dev, pmem->phys_addr,
 				pmem->size, ARCH_MEMREMAP_PMEM);
···
 			/ 512);
 	if (devm_init_badblocks(dev, &pmem->bb))
 		return -ENOMEM;
-	nvdimm_badblocks_populate(nd_region, &pmem->bb, res);
+	nvdimm_badblocks_populate(nd_region, &pmem->bb, &bb_res);
 	disk->bb = &pmem->bb;
 
 	dax_dev = alloc_dax(pmem, disk->disk_name, &pmem_dax_ops);

drivers/nvdimm/pmem.h

···
 	struct badblocks	bb;
 	struct dax_device	*dax_dev;
 	struct gendisk		*disk;
+	struct dev_pagemap	pgmap;
 };
 
 long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,

include/linux/memremap.h

···
 };
 
 #ifdef CONFIG_ZONE_DEVICE
-void *devm_memremap_pages(struct device *dev, struct resource *res,
-		struct percpu_ref *ref, struct vmem_altmap *altmap);
+void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 		struct dev_pagemap *pgmap);
 
···
 static inline bool is_zone_device_page(const struct page *page);
 #else
 static inline void *devm_memremap_pages(struct device *dev,
-		struct resource *res, struct percpu_ref *ref,
-		struct vmem_altmap *altmap)
+		struct dev_pagemap *pgmap)
 {
 	/*
 	 * Fail attempts to call devm_memremap_pages() without

kernel/memremap.c

···
 #define for_each_device_pfn(pfn, map) \
 	for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++)
 
-static void devm_memremap_pages_release(struct device *dev, void *data)
+static void devm_memremap_pages_release(void *data)
 {
 	struct dev_pagemap *pgmap = data;
+	struct device *dev = pgmap->dev;
 	struct resource *res = &pgmap->res;
 	resource_size_t align_start, align_size;
 	unsigned long pfn;
···
 /**
  * devm_memremap_pages - remap and provide memmap backing for the given resource
  * @dev: hosting device for @res
- * @res: "host memory" address range
- * @ref: a live per-cpu reference count
- * @altmap: optional descriptor for allocating the memmap from @res
+ * @pgmap: pointer to a struct dev_pgmap
  *
  * Notes:
- * 1/ @ref must be 'live' on entry and 'dead' before devm_memunmap_pages() time
- *    (or devm release event). The expected order of events is that @ref has
+ * 1/ At a minimum the res, ref and type members of @pgmap must be initialized
+ *    by the caller before passing it to this function
+ *
+ * 2/ The altmap field may optionally be initialized, in which case altmap_valid
+ *    must be set to true
+ *
+ * 3/ pgmap.ref must be 'live' on entry and 'dead' before devm_memunmap_pages()
+ *    time (or devm release event). The expected order of events is that ref has
  *    been through percpu_ref_kill() before devm_memremap_pages_release(). The
  *    wait for the completion of all references being dropped and
  *    percpu_ref_exit() must occur after devm_memremap_pages_release().
  *
- * 2/ @res is expected to be a host memory range that could feasibly be
+ * 4/ res is expected to be a host memory range that could feasibly be
  *    treated as a "System RAM" range, i.e. not a device mmio range, but
  *    this is not enforced.
  */
-void *devm_memremap_pages(struct device *dev, struct resource *res,
-		struct percpu_ref *ref, struct vmem_altmap *altmap)
+void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 {
 	resource_size_t align_start, align_size, align_end;
+	struct vmem_altmap *altmap = pgmap->altmap_valid ?
+			&pgmap->altmap : NULL;
 	unsigned long pfn, pgoff, order;
 	pgprot_t pgprot = PAGE_KERNEL;
-	struct dev_pagemap *pgmap;
 	int error, nid, is_ram, i = 0;
+	struct resource *res = &pgmap->res;
 
 	align_start = res->start & ~(SECTION_SIZE - 1);
 	align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
···
 	if (is_ram == REGION_INTERSECTS)
 		return __va(res->start);
 
-	if (!ref)
+	if (!pgmap->ref)
 		return ERR_PTR(-EINVAL);
 
-	pgmap = devres_alloc_node(devm_memremap_pages_release,
-			sizeof(*pgmap), GFP_KERNEL, dev_to_node(dev));
-	if (!pgmap)
-		return ERR_PTR(-ENOMEM);
-
-	memcpy(&pgmap->res, res, sizeof(*res));
-
 	pgmap->dev = dev;
-	if (altmap) {
-		memcpy(&pgmap->altmap, altmap, sizeof(*altmap));
-		pgmap->altmap_valid = true;
-		altmap = &pgmap->altmap;
-	}
-	pgmap->ref = ref;
-	pgmap->type = MEMORY_DEVICE_HOST;
-	pgmap->page_fault = NULL;
-	pgmap->page_free = NULL;
-	pgmap->data = NULL;
 
 	mutex_lock(&pgmap_lock);
 	error = 0;
···
 		 */
 		list_del(&page->lru);
 		page->pgmap = pgmap;
-		percpu_ref_get(ref);
+		percpu_ref_get(pgmap->ref);
 		if (!(++i % 1024))
 			cond_resched();
 	}
-	devres_add(dev, pgmap);
+
+	devm_add_action(dev, devm_memremap_pages_release, pgmap);
+
 	return __va(res->start);
 
  err_add_memory:

tools/testing/nvdimm/test/iomap.c

···
 }
 EXPORT_SYMBOL(__wrap_devm_memremap);
 
-void *__wrap_devm_memremap_pages(struct device *dev, struct resource *res,
-		struct percpu_ref *ref, struct vmem_altmap *altmap)
+void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 {
-	resource_size_t offset = res->start;
+	resource_size_t offset = pgmap->res.start;
 	struct nfit_test_resource *nfit_res = get_nfit_res(offset);
 
 	if (nfit_res)
 		return nfit_res->buf + offset - nfit_res->res.start;
-	return devm_memremap_pages(dev, res, ref, altmap);
+	return devm_memremap_pages(dev, pgmap);
 }
 EXPORT_SYMBOL(__wrap_devm_memremap_pages);