From 244b2c5ca8b14627e4a17755e5922221e121c771 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 09 Oct 2024 06:15:07 +0000
Subject: [PATCH] change system file

---
 kernel/drivers/nvdimm/region_devs.c |  502 +++++++++++++++++++++++++++++++------------------------
 1 files changed, 284 insertions(+), 218 deletions(-)

diff --git a/kernel/drivers/nvdimm/region_devs.c b/kernel/drivers/nvdimm/region_devs.c
index 71cfdc3..1d72653 100644
--- a/kernel/drivers/nvdimm/region_devs.c
+++ b/kernel/drivers/nvdimm/region_devs.c
@@ -1,16 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright(c) 2013-2015 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/scatterlist.h>
+#include <linux/memregion.h>
 #include <linux/highmem.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
@@ -27,7 +20,6 @@
  */
 #include <linux/io-64-nonatomic-hi-lo.h>
 
-static DEFINE_IDA(region_ida);
 static DEFINE_PER_CPU(int, flush_idx);
 
 static int nvdimm_map_flush(struct device *dev, struct nvdimm *nvdimm, int dimm,
@@ -78,6 +70,11 @@
 	for (i = 0; i < nd_region->ndr_mappings; i++) {
 		struct nd_mapping *nd_mapping = &nd_region->mapping[i];
 		struct nvdimm *nvdimm = nd_mapping->nvdimm;
+
+		if (test_bit(NDD_SECURITY_OVERWRITE, &nvdimm->flags)) {
+			nvdimm_bus_unlock(&nd_region->dev);
+			return -EBUSY;
+		}
 
 		/* at least one null hint slot per-dimm for the "no-hint" case */
 		flush_data_size += sizeof(void *);
@@ -136,41 +133,11 @@
 		put_device(&nvdimm->dev);
 	}
 	free_percpu(nd_region->lane);
-	ida_simple_remove(&region_ida, nd_region->id);
+	memregion_free(nd_region->id);
 	if (is_nd_blk(dev))
 		kfree(to_nd_blk_region(dev));
 	else
 		kfree(nd_region);
-}
-
-static struct device_type nd_blk_device_type = {
-	.name = "nd_blk",
-	.release = nd_region_release,
-};
-
-static struct device_type nd_pmem_device_type = {
-	.name = "nd_pmem",
-	.release = nd_region_release,
-};
-
-static struct device_type nd_volatile_device_type = {
-	.name = "nd_volatile",
-	.release = nd_region_release,
-};
-
-bool is_nd_pmem(struct device *dev)
-{
-	return dev ? dev->type == &nd_pmem_device_type : false;
-}
-
-bool is_nd_blk(struct device *dev)
-{
-	return dev ? dev->type == &nd_blk_device_type : false;
-}
-
-bool is_nd_volatile(struct device *dev)
-{
-	return dev ? dev->type == &nd_volatile_device_type : false;
 }
 
 struct nd_region *to_nd_region(struct device *dev)
@@ -228,16 +195,16 @@
 int nd_region_to_nstype(struct nd_region *nd_region)
 {
 	if (is_memory(&nd_region->dev)) {
-		u16 i, alias;
+		u16 i, label;
 
-		for (i = 0, alias = 0; i < nd_region->ndr_mappings; i++) {
+		for (i = 0, label = 0; i < nd_region->ndr_mappings; i++) {
 			struct nd_mapping *nd_mapping = &nd_region->mapping[i];
 			struct nvdimm *nvdimm = nd_mapping->nvdimm;
 
-			if (test_bit(NDD_ALIASING, &nvdimm->flags))
-				alias++;
+			if (test_bit(NDD_LABELING, &nvdimm->flags))
+				label++;
 		}
-		if (alias)
+		if (label)
 			return ND_DEVICE_NAMESPACE_PMEM;
 		else
 			return ND_DEVICE_NAMESPACE_IO;
@@ -249,21 +216,25 @@
 }
 EXPORT_SYMBOL(nd_region_to_nstype);
 
+static unsigned long long region_size(struct nd_region *nd_region)
+{
+	if (is_memory(&nd_region->dev)) {
+		return nd_region->ndr_size;
+	} else if (nd_region->ndr_mappings == 1) {
+		struct nd_mapping *nd_mapping = &nd_region->mapping[0];
+
+		return nd_mapping->size;
+	}
+
+	return 0;
+}
+
 static ssize_t size_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nd_region *nd_region = to_nd_region(dev);
-	unsigned long long size = 0;
 
-	if (is_memory(dev)) {
-		size = nd_region->ndr_size;
-	} else if (nd_region->ndr_mappings == 1) {
-		struct nd_mapping *nd_mapping = &nd_region->mapping[0];
-
-		size = nd_mapping->size;
-	}
-
-	return sprintf(buf, "%llu\n", size);
+	return sprintf(buf, "%llu\n", region_size(nd_region));
 }
 static DEVICE_ATTR_RO(size);
 
@@ -334,7 +305,7 @@
 	 * the v1.1 namespace label cookie definition. To read all this
 	 * data we need to wait for probing to settle.
 	 */
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	if (nd_region->ndr_mappings) {
@@ -351,7 +322,7 @@
 		}
 	}
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	if (rc)
 		return rc;
@@ -427,12 +398,12 @@
 	 * memory nvdimm_bus_lock() is dropped, but that's userspace's
 	 * problem to not race itself.
 	 */
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	available = nd_region_available_dpa(nd_region);
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return sprintf(buf, "%llu\n", available);
 }
@@ -444,12 +415,12 @@
 	struct nd_region *nd_region = to_nd_region(dev);
 	unsigned long long available = 0;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	nvdimm_bus_lock(dev);
 	wait_nvdimm_bus_probe_idle(dev);
 	available = nd_region_allocatable_dpa(nd_region);
 	nvdimm_bus_unlock(dev);
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return sprintf(buf, "%llu\n", available);
 }
@@ -562,18 +533,66 @@
 }
 static DEVICE_ATTR_RW(read_only);
 
+static ssize_t align_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_region *nd_region = to_nd_region(dev);
+
+	return sprintf(buf, "%#lx\n", nd_region->align);
+}
+
+static ssize_t align_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct nd_region *nd_region = to_nd_region(dev);
+	unsigned long val, dpa;
+	u32 remainder;
+	int rc;
+
+	rc = kstrtoul(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	if (!nd_region->ndr_mappings)
+		return -ENXIO;
+
+	/*
+	 * Ensure space-align is evenly divisible by the region
+	 * interleave-width because the kernel typically has no facility
+	 * to determine which DIMM(s), dimm-physical-addresses, would
+	 * contribute to the tail capacity in system-physical-address
+	 * space for the namespace.
+	 */
+	dpa = div_u64_rem(val, nd_region->ndr_mappings, &remainder);
+	if (!is_power_of_2(dpa) || dpa < PAGE_SIZE
+			|| val > region_size(nd_region) || remainder)
+		return -EINVAL;
+
+	/*
+	 * Given that space allocation consults this value multiple
+	 * times ensure it does not change for the duration of the
+	 * allocation.
+	 */
+	nvdimm_bus_lock(dev);
+	nd_region->align = val;
+	nvdimm_bus_unlock(dev);
+
+	return len;
+}
+static DEVICE_ATTR_RW(align);
+
 static ssize_t region_badblocks_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct nd_region *nd_region = to_nd_region(dev);
 	ssize_t rc;
 
-	device_lock(dev);
+	nd_device_lock(dev);
 	if (dev->driver)
 		rc = badblocks_show(&nd_region->bb, buf, 0);
 	else
 		rc = -ENXIO;
-	device_unlock(dev);
+	nd_device_unlock(dev);
 
 	return rc;
 }
@@ -586,7 +605,7 @@
 
 	return sprintf(buf, "%#llx\n", nd_region->ndr_start);
 }
-static DEVICE_ATTR_RO(resource);
+static DEVICE_ATTR_ADMIN_RO(resource);
 
 static ssize_t persistence_domain_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
@@ -604,6 +623,7 @@
 
 static struct attribute *nd_region_attributes[] = {
 	&dev_attr_size.attr,
+	&dev_attr_align.attr,
 	&dev_attr_nstype.attr,
 	&dev_attr_mappings.attr,
 	&dev_attr_btt_seed.attr,
@@ -638,12 +658,8 @@
 	if (!is_memory(dev) && a == &dev_attr_badblocks.attr)
 		return 0;
 
-	if (a == &dev_attr_resource.attr) {
-		if (is_memory(dev))
-			return 0400;
-		else
-			return 0;
-	}
+	if (a == &dev_attr_resource.attr && !is_memory(dev))
+		return 0;
 
 	if (a == &dev_attr_deep_flush.attr) {
 		int has_flush = nvdimm_has_flush(nd_region);
@@ -663,6 +679,9 @@
 		return a->mode;
 	}
 
+	if (a == &dev_attr_align.attr)
+		return a->mode;
+
 	if (a != &dev_attr_set_cookie.attr
 			&& a != &dev_attr_available_size.attr)
 		return a->mode;
@@ -675,128 +694,6 @@
 		return a->mode;
 
 	return 0;
-}
-
-struct attribute_group nd_region_attribute_group = {
-	.attrs = nd_region_attributes,
-	.is_visible = region_visible,
-};
-EXPORT_SYMBOL_GPL(nd_region_attribute_group);
-
-u64 nd_region_interleave_set_cookie(struct nd_region *nd_region,
-		struct nd_namespace_index *nsindex)
-{
-	struct nd_interleave_set *nd_set = nd_region->nd_set;
-
-	if (!nd_set)
-		return 0;
-
-	if (nsindex && __le16_to_cpu(nsindex->major) == 1
-			&& __le16_to_cpu(nsindex->minor) == 1)
-		return nd_set->cookie1;
-	return nd_set->cookie2;
-}
-
-u64 nd_region_interleave_set_altcookie(struct nd_region *nd_region)
-{
-	struct nd_interleave_set *nd_set = nd_region->nd_set;
-
-	if (nd_set)
-		return nd_set->altcookie;
-	return 0;
-}
-
-void nd_mapping_free_labels(struct nd_mapping *nd_mapping)
-{
-	struct nd_label_ent *label_ent, *e;
-
-	lockdep_assert_held(&nd_mapping->lock);
-	list_for_each_entry_safe(label_ent, e, &nd_mapping->labels, list) {
-		list_del(&label_ent->list);
-		kfree(label_ent);
-	}
-}
-
-/*
- * Upon successful probe/remove, take/release a reference on the
- * associated interleave set (if present), and plant new btt + namespace
- * seeds.  Also, on the removal of a BLK region, notify the provider to
- * disable the region.
- */
-static void nd_region_notify_driver_action(struct nvdimm_bus *nvdimm_bus,
-		struct device *dev, bool probe)
-{
-	struct nd_region *nd_region;
-
-	if (!probe && is_nd_region(dev)) {
-		int i;
-
-		nd_region = to_nd_region(dev);
-		for (i = 0; i < nd_region->ndr_mappings; i++) {
-			struct nd_mapping *nd_mapping = &nd_region->mapping[i];
-			struct nvdimm_drvdata *ndd = nd_mapping->ndd;
-			struct nvdimm *nvdimm = nd_mapping->nvdimm;
-
-			mutex_lock(&nd_mapping->lock);
-			nd_mapping_free_labels(nd_mapping);
-			mutex_unlock(&nd_mapping->lock);
-
-			put_ndd(ndd);
-			nd_mapping->ndd = NULL;
-			if (ndd)
-				atomic_dec(&nvdimm->busy);
-		}
-	}
-	if (dev->parent && is_nd_region(dev->parent) && probe) {
-		nd_region = to_nd_region(dev->parent);
-		nvdimm_bus_lock(dev);
-		if (nd_region->ns_seed == dev)
-			nd_region_create_ns_seed(nd_region);
-		nvdimm_bus_unlock(dev);
-	}
-	if (is_nd_btt(dev) && probe) {
-		struct nd_btt *nd_btt = to_nd_btt(dev);
-
-		nd_region = to_nd_region(dev->parent);
-		nvdimm_bus_lock(dev);
-		if (nd_region->btt_seed == dev)
-			nd_region_create_btt_seed(nd_region);
-		if (nd_region->ns_seed == &nd_btt->ndns->dev)
-			nd_region_create_ns_seed(nd_region);
-		nvdimm_bus_unlock(dev);
-	}
-	if (is_nd_pfn(dev) && probe) {
-		struct nd_pfn *nd_pfn = to_nd_pfn(dev);
-
-		nd_region = to_nd_region(dev->parent);
-		nvdimm_bus_lock(dev);
-		if (nd_region->pfn_seed == dev)
-			nd_region_create_pfn_seed(nd_region);
-		if (nd_region->ns_seed == &nd_pfn->ndns->dev)
-			nd_region_create_ns_seed(nd_region);
-		nvdimm_bus_unlock(dev);
-	}
-	if (is_nd_dax(dev) && probe) {
-		struct nd_dax *nd_dax = to_nd_dax(dev);
-
-		nd_region = to_nd_region(dev->parent);
-		nvdimm_bus_lock(dev);
-		if (nd_region->dax_seed == dev)
-			nd_region_create_dax_seed(nd_region);
-		if (nd_region->ns_seed == &nd_dax->nd_pfn.ndns->dev)
-			nd_region_create_ns_seed(nd_region);
-		nvdimm_bus_unlock(dev);
-	}
-}
-
-void nd_region_probe_success(struct nvdimm_bus *nvdimm_bus, struct device *dev)
-{
-	nd_region_notify_driver_action(nvdimm_bus, dev, true);
-}
-
-void nd_region_disable(struct nvdimm_bus *nvdimm_bus, struct device *dev)
-{
-	nd_region_notify_driver_action(nvdimm_bus, dev, false);
 }
 
 static ssize_t mappingN(struct device *dev, char *buf, int n)
@@ -906,11 +803,124 @@
 	NULL,
 };
 
-struct attribute_group nd_mapping_attribute_group = {
+static const struct attribute_group nd_mapping_attribute_group = {
 	.is_visible = mapping_visible,
 	.attrs = mapping_attributes,
 };
-EXPORT_SYMBOL_GPL(nd_mapping_attribute_group);
+
+static const struct attribute_group nd_region_attribute_group = {
+	.attrs = nd_region_attributes,
+	.is_visible = region_visible,
+};
+
+static const struct attribute_group *nd_region_attribute_groups[] = {
+	&nd_device_attribute_group,
+	&nd_region_attribute_group,
+	&nd_numa_attribute_group,
+	&nd_mapping_attribute_group,
+	NULL,
+};
+
+static const struct device_type nd_blk_device_type = {
+	.name = "nd_blk",
+	.release = nd_region_release,
+	.groups = nd_region_attribute_groups,
+};
+
+static const struct device_type nd_pmem_device_type = {
+	.name = "nd_pmem",
+	.release = nd_region_release,
+	.groups = nd_region_attribute_groups,
+};
+
+static const struct device_type nd_volatile_device_type = {
+	.name = "nd_volatile",
+	.release = nd_region_release,
+	.groups = nd_region_attribute_groups,
+};
+
+bool is_nd_pmem(struct device *dev)
+{
+	return dev ? dev->type == &nd_pmem_device_type : false;
+}
+
+bool is_nd_blk(struct device *dev)
+{
+	return dev ? dev->type == &nd_blk_device_type : false;
+}
+
+bool is_nd_volatile(struct device *dev)
+{
+	return dev ? dev->type == &nd_volatile_device_type : false;
+}
+
+u64 nd_region_interleave_set_cookie(struct nd_region *nd_region,
+		struct nd_namespace_index *nsindex)
+{
+	struct nd_interleave_set *nd_set = nd_region->nd_set;
+
+	if (!nd_set)
+		return 0;
+
+	if (nsindex && __le16_to_cpu(nsindex->major) == 1
+			&& __le16_to_cpu(nsindex->minor) == 1)
+		return nd_set->cookie1;
+	return nd_set->cookie2;
+}
+
+u64 nd_region_interleave_set_altcookie(struct nd_region *nd_region)
+{
+	struct nd_interleave_set *nd_set = nd_region->nd_set;
+
+	if (nd_set)
+		return nd_set->altcookie;
+	return 0;
+}
+
+void nd_mapping_free_labels(struct nd_mapping *nd_mapping)
+{
+	struct nd_label_ent *label_ent, *e;
+
+	lockdep_assert_held(&nd_mapping->lock);
+	list_for_each_entry_safe(label_ent, e, &nd_mapping->labels, list) {
+		list_del(&label_ent->list);
+		kfree(label_ent);
+	}
+}
+
+/*
+ * When a namespace is activated create new seeds for the next
+ * namespace, or namespace-personality to be configured.
+ */
+void nd_region_advance_seeds(struct nd_region *nd_region, struct device *dev)
+{
+	nvdimm_bus_lock(dev);
+	if (nd_region->ns_seed == dev) {
+		nd_region_create_ns_seed(nd_region);
+	} else if (is_nd_btt(dev)) {
+		struct nd_btt *nd_btt = to_nd_btt(dev);
+
+		if (nd_region->btt_seed == dev)
+			nd_region_create_btt_seed(nd_region);
+		if (nd_region->ns_seed == &nd_btt->ndns->dev)
+			nd_region_create_ns_seed(nd_region);
+	} else if (is_nd_pfn(dev)) {
+		struct nd_pfn *nd_pfn = to_nd_pfn(dev);
+
+		if (nd_region->pfn_seed == dev)
+			nd_region_create_pfn_seed(nd_region);
+		if (nd_region->ns_seed == &nd_pfn->ndns->dev)
+			nd_region_create_ns_seed(nd_region);
+	} else if (is_nd_dax(dev)) {
+		struct nd_dax *nd_dax = to_nd_dax(dev);
+
+		if (nd_region->dax_seed == dev)
+			nd_region_create_dax_seed(nd_region);
+		if (nd_region->ns_seed == &nd_dax->nd_pfn.ndns->dev)
+			nd_region_create_ns_seed(nd_region);
+	}
+	nvdimm_bus_unlock(dev);
+}
 
 int nd_blk_region_init(struct nd_region *nd_region)
 {
@@ -981,9 +991,47 @@
 }
 EXPORT_SYMBOL(nd_region_release_lane);
 
+/*
+ * PowerPC requires this alignment for memremap_pages(). All other archs
+ * should be ok with SUBSECTION_SIZE (see memremap_compat_align()).
+ */
+#define MEMREMAP_COMPAT_ALIGN_MAX SZ_16M
+
+static unsigned long default_align(struct nd_region *nd_region)
+{
+	unsigned long align;
+	int i, mappings;
+	u32 remainder;
+
+	if (is_nd_blk(&nd_region->dev))
+		align = PAGE_SIZE;
+	else
+		align = MEMREMAP_COMPAT_ALIGN_MAX;
+
+	for (i = 0; i < nd_region->ndr_mappings; i++) {
+		struct nd_mapping *nd_mapping = &nd_region->mapping[i];
+		struct nvdimm *nvdimm = nd_mapping->nvdimm;
+
+		if (test_bit(NDD_ALIASING, &nvdimm->flags)) {
+			align = MEMREMAP_COMPAT_ALIGN_MAX;
+			break;
+		}
+	}
+
+	if (nd_region->ndr_size < MEMREMAP_COMPAT_ALIGN_MAX)
+		align = PAGE_SIZE;
+
+	mappings = max_t(u16, 1, nd_region->ndr_mappings);
+	div_u64_rem(align, mappings, &remainder);
+	if (remainder)
+		align *= mappings;
+
+	return align;
+}
+
 static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
-		struct nd_region_desc *ndr_desc, struct device_type *dev_type,
-		const char *caller)
+		struct nd_region_desc *ndr_desc,
+		const struct device_type *dev_type, const char *caller)
 {
 	struct nd_region *nd_region;
 	struct device *dev;
@@ -995,15 +1043,22 @@
 		struct nd_mapping_desc *mapping = &ndr_desc->mapping[i];
 		struct nvdimm *nvdimm = mapping->nvdimm;
 
-		if ((mapping->start | mapping->size) % SZ_4K) {
-			dev_err(&nvdimm_bus->dev, "%s: %s mapping%d is not 4K aligned\n",
-					caller, dev_name(&nvdimm->dev), i);
-
+		if ((mapping->start | mapping->size) % PAGE_SIZE) {
+			dev_err(&nvdimm_bus->dev,
+				"%s: %s mapping%d is not %ld aligned\n",
+				caller, dev_name(&nvdimm->dev), i, PAGE_SIZE);
 			return NULL;
 		}
 
 		if (test_bit(NDD_UNARMED, &nvdimm->flags))
 			ro = 1;
+
+		if (test_bit(NDD_NOBLK, &nvdimm->flags)
+				&& dev_type == &nd_blk_device_type) {
+			dev_err(&nvdimm_bus->dev, "%s: %s mapping%d is not BLK capable\n",
+					caller, dev_name(&nvdimm->dev), i);
+			return NULL;
+		}
 	}
 
 	if (dev_type == &nd_blk_device_type) {
@@ -1021,16 +1076,15 @@
 		}
 		region_buf = ndbr;
 	} else {
-		nd_region = kzalloc(sizeof(struct nd_region)
-				+ sizeof(struct nd_mapping)
-				* ndr_desc->num_mappings,
-				GFP_KERNEL);
+		nd_region = kzalloc(struct_size(nd_region, mapping,
+						ndr_desc->num_mappings),
+				    GFP_KERNEL);
 		region_buf = nd_region;
 	}
 
 	if (!region_buf)
 		return NULL;
-	nd_region->id = ida_simple_get(&region_ida, 0, 0, GFP_KERNEL);
+	nd_region->id = memregion_alloc(GFP_KERNEL);
 	if (nd_region->id < 0)
 		goto err_id;
 
@@ -1066,6 +1120,7 @@
 	nd_region->flags = ndr_desc->flags;
 	nd_region->ro = ro;
 	nd_region->numa_node = ndr_desc->numa_node;
+	nd_region->target_node = ndr_desc->target_node;
 	ida_init(&nd_region->ns_ida);
 	ida_init(&nd_region->btt_ida);
 	ida_init(&nd_region->pfn_ida);
@@ -1078,6 +1133,7 @@
 	dev->of_node = ndr_desc->of_node;
 	nd_region->ndr_size = resource_size(ndr_desc->res);
 	nd_region->ndr_start = ndr_desc->res->start;
+	nd_region->align = default_align(nd_region);
 	if (ndr_desc->flush)
 		nd_region->flush = ndr_desc->flush;
 	else
@@ -1088,7 +1144,7 @@
 	return nd_region;
 
  err_percpu:
-	ida_simple_remove(&region_ida, nd_region->id);
+	memregion_free(nd_region->id);
  err_id:
 	kfree(region_buf);
 	return NULL;
@@ -1153,13 +1209,13 @@
 	idx = this_cpu_add_return(flush_idx, hash_32(current->pid + idx, 8));
 
 	/*
-	 * The first wmb() is needed to 'sfence' all previous writes
-	 * such that they are architecturally visible for the platform
-	 * buffer flush.  Note that we've already arranged for pmem
+	 * The pmem_wmb() is needed to 'sfence' all
+	 * previous writes such that they are architecturally visible for
+	 * the platform buffer flush. Note that we've already arranged for pmem
 	 * writes to avoid the cache via memcpy_flushcache().  The final
 	 * wmb() ensures ordering for the NVDIMM flush write.
 	 */
-	wmb();
+	pmem_wmb();
 	for (i = 0; i < nd_region->ndr_mappings; i++)
 		if (ndrd_get_flush_wpq(ndrd, i, 0))
 			writeq(1, ndrd_get_flush_wpq(ndrd, i, idx));
@@ -1186,6 +1242,11 @@
 			|| !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
 		return -ENXIO;
 
+	/* Test if an explicit flush function is defined */
+	if (test_bit(ND_REGION_ASYNC, &nd_region->flags) && nd_region->flush)
+		return 1;
+
+	/* Test if any flush hints for the region are available */
 	for (i = 0; i < nd_region->ndr_mappings; i++) {
 		struct nd_mapping *nd_mapping = &nd_region->mapping[i];
 		struct nvdimm *nvdimm = nd_mapping->nvdimm;
@@ -1196,8 +1257,8 @@
 	}
 
 	/*
-	 * The platform defines dimm devices without hints, assume
-	 * platform persistence mechanism like ADR
+	 * The platform defines dimm devices without hints nor explicit flush,
+	 * assume platform persistence mechanism like ADR
 	 */
 	return 0;
 }
@@ -1209,6 +1270,16 @@
 		!test_bit(ND_REGION_PERSIST_CACHE, &nd_region->flags);
 }
 EXPORT_SYMBOL_GPL(nvdimm_has_cache);
+
+bool is_nvdimm_sync(struct nd_region *nd_region)
+{
+	if (is_nd_volatile(&nd_region->dev))
+		return true;
+
+	return is_nd_pmem(&nd_region->dev) &&
+		!test_bit(ND_REGION_ASYNC, &nd_region->flags);
+}
+EXPORT_SYMBOL_GPL(is_nvdimm_sync);
 
 struct conflict_context {
 	struct nd_region *nd_region;
@@ -1249,9 +1320,4 @@
 	};
 
 	return device_for_each_child(&nvdimm_bus->dev, &ctx, region_conflict);
-}
-
-void __exit nd_region_devs_exit(void)
-{
-	ida_destroy(&region_ida);
 }

--
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