Merge tag 'libnvdimm-for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm updates from Dan Williams:
 "This adds a user for the new 'bytes-remaining' updates to
  memcpy_mcsafe() that you already received through Ingo via the
  x86-dax- for-linus pull.

  Not included here, but still targeting this cycle, is support for
  handling memory media errors (poison) consumed via userspace dax
  mappings.

  Summary:

   - DAX broke a fundamental assumption of truncate of file mapped
     pages. The truncate path assumed that it is safe to disconnect a
     pinned page from a file and let the filesystem reclaim the physical
     block. With DAX the page is equivalent to the filesystem block.
     Introduce dax_layout_busy_page() to enable filesystems to wait for
     pinned DAX pages to be released. Without this wait a filesystem
     could allocate blocks under active device-DMA to a new file.

   - DAX arranges for the block layer to be bypassed and uses
     dax_direct_access() + copy_to_iter() to satisfy read(2) calls.
     However, the memcpy_mcsafe() facility is available through the pmem
     block driver. In order to safely handle media errors, via the DAX
     block-layer bypass, introduce copy_to_iter_mcsafe().

   - Fix cache management policy relative to the ACPI NFIT Platform
     Capabilities Structure to properly elide cache flushes when they
     are not necessary. The table indicates whether CPU caches are
     power-fail protected. Clarify that a deep flush is always performed
     on REQ_{FUA,PREFLUSH} requests"

* tag 'libnvdimm-for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (21 commits)
  dax: Use dax_write_cache* helpers
  libnvdimm, pmem: Do not flush power-fail protected CPU caches
  libnvdimm, pmem: Unconditionally deep flush on *sync
  libnvdimm, pmem: Complete REQ_FLUSH => REQ_PREFLUSH
  acpi, nfit: Remove ecc_unit_size
  dax: dax_insert_mapping_entry always succeeds
  libnvdimm, e820: Register all pmem resources
  libnvdimm: Debug probe times
  linvdimm, pmem: Preserve read-only setting for pmem devices
  x86, nfit_test: Add unit test for memcpy_mcsafe()
  pmem: Switch to copy_to_iter_mcsafe()
  dax: Report bytes remaining in dax_iomap_actor()
  dax: Introduce a ->copy_to_iter dax operation
  uio, lib: Fix CONFIG_ARCH_HAS_UACCESS_MCSAFE compilation
  xfs, dax: introduce xfs_break_dax_layouts()
  xfs: prepare xfs_break_layouts() for another layout type
  xfs: prepare xfs_break_layouts() to be called with XFS_MMAPLOCK_EXCL
  mm, fs, dax: handle layout changes to pinned dax mappings
  mm: fix __gup_device_huge vs unmap
  mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS
  ...

12 files changed, 181 insertions, 58 deletions

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index e2235ed3e4be..b87252bf4571 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1978,19 +1978,8 @@ static ssize_t range_index_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(range_index);
 
-static ssize_t ecc_unit_size_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct nd_region *nd_region = to_nd_region(dev);
-	struct nfit_spa *nfit_spa = nd_region_provider_data(nd_region);
-
-	return sprintf(buf, "%d\n", nfit_spa->clear_err_unit);
-}
-static DEVICE_ATTR_RO(ecc_unit_size);
-
 static struct attribute *acpi_nfit_region_attributes[] = {
 	&dev_attr_range_index.attr,
-	&dev_attr_ecc_unit_size.attr,
 	NULL,
 };
 
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 1d7bd96511f0..903d9c473749 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -85,6 +85,7 @@ EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
 bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 {
 	struct dax_device *dax_dev;
+	bool dax_enabled = false;
 	pgoff_t pgoff;
 	int err, id;
 	void *kaddr;
@@ -134,14 +135,21 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 		 * on being able to do (page_address(pfn_to_page())).
 		 */
 		WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API));
+		dax_enabled = true;
 	} else if (pfn_t_devmap(pfn)) {
-		/* pass */;
-	} else {
+		struct dev_pagemap *pgmap;
+
+		pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
+		if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX)
+			dax_enabled = true;
+		put_dev_pagemap(pgmap);
+	}
+
+	if (!dax_enabled) {
 		pr_debug("%s: error: dax support not enabled\n",
 				bdevname(bdev, buf));
 		return false;
 	}
-
 	return true;
 }
 EXPORT_SYMBOL_GPL(__bdev_dax_supported);
@@ -182,8 +190,7 @@ static ssize_t write_cache_show(struct device *dev,
 	if (!dax_dev)
 		return -ENXIO;
 
-	rc = sprintf(buf, "%d\n", !!test_bit(DAXDEV_WRITE_CACHE,
-				&dax_dev->flags));
+	rc = sprintf(buf, "%d\n", !!dax_write_cache_enabled(dax_dev));
 	put_dax(dax_dev);
 	return rc;
 }
@@ -201,10 +208,8 @@ static ssize_t write_cache_store(struct device *dev,
 
 	if (rc)
 		len = rc;
-	else if (write_cache)
-		set_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags);
 	else
-		clear_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags);
+		dax_write_cache(dax_dev, write_cache);
 
 	put_dax(dax_dev);
 	return len;
@@ -282,11 +287,21 @@ size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
 }
 EXPORT_SYMBOL_GPL(dax_copy_from_iter);
 
+size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
+		size_t bytes, struct iov_iter *i)
+{
+	if (!dax_alive(dax_dev))
+		return 0;
+
+	return dax_dev->ops->copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+}
+EXPORT_SYMBOL_GPL(dax_copy_to_iter);
+
 #ifdef CONFIG_ARCH_HAS_PMEM_API
 void arch_wb_cache_pmem(void *addr, size_t size);
 void dax_flush(struct dax_device *dax_dev, void *addr, size_t size)
 {
-	if (unlikely(!test_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags)))
+	if (unlikely(!dax_write_cache_enabled(dax_dev)))
 		return;
 
 	arch_wb_cache_pmem(addr, size);
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 775c06d953b7..d10964d41fd7 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -185,9 +185,24 @@ static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
 	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
 }
 
+static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct linear_c *lc = ti->private;
+	struct block_device *bdev = lc->dev->bdev;
+	struct dax_device *dax_dev = lc->dev->dax_dev;
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+
+	dev_sector = linear_map_sector(ti, sector);
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
 #else
 #define linear_dax_direct_access NULL
 #define linear_dax_copy_from_iter NULL
+#define linear_dax_copy_to_iter NULL
 #endif
 
 static struct target_type linear_target = {
@@ -204,6 +219,7 @@ static struct target_type linear_target = {
 	.iterate_devices = linear_iterate_devices,
 	.direct_access = linear_dax_direct_access,
 	.dax_copy_from_iter = linear_dax_copy_from_iter,
+	.dax_copy_to_iter = linear_dax_copy_to_iter,
 };
 
 int __init dm_linear_init(void)
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index c90c7c08a77f..9ea2b0291f20 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -962,9 +962,23 @@ static size_t log_writes_dax_copy_from_iter(struct dm_target *ti,
 dax_copy:
 	return dax_copy_from_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
 }
+
+static size_t log_writes_dax_copy_to_iter(struct dm_target *ti,
+					  pgoff_t pgoff, void *addr, size_t bytes,
+					  struct iov_iter *i)
+{
+	struct log_writes_c *lc = ti->private;
+	sector_t sector = pgoff * PAGE_SECTORS;
+
+	if (bdev_dax_pgoff(lc->dev->bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_to_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
+}
+
 #else
 #define log_writes_dax_direct_access NULL
 #define log_writes_dax_copy_from_iter NULL
+#define log_writes_dax_copy_to_iter NULL
 #endif
 
 static struct target_type log_writes_target = {
@@ -982,6 +996,7 @@ static struct target_type log_writes_target = {
 	.io_hints = log_writes_io_hints,
 	.direct_access = log_writes_dax_direct_access,
 	.dax_copy_from_iter = log_writes_dax_copy_from_iter,
+	.dax_copy_to_iter = log_writes_dax_copy_to_iter,
 };
 
 static int __init dm_log_writes_init(void)
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index fe7fb9b1aec3..8547d7594338 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -354,9 +354,29 @@ static size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
 	return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
 }
 
+static size_t stripe_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+	struct stripe_c *sc = ti->private;
+	struct dax_device *dax_dev;
+	struct block_device *bdev;
+	uint32_t stripe;
+
+	stripe_map_sector(sc, sector, &stripe, &dev_sector);
+	dev_sector += sc->stripe[stripe].physical_start;
+	dax_dev = sc->stripe[stripe].dev->dax_dev;
+	bdev = sc->stripe[stripe].dev->bdev;
+
+	if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+		return 0;
+	return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+}
+
 #else
 #define stripe_dax_direct_access NULL
 #define stripe_dax_copy_from_iter NULL
+#define stripe_dax_copy_to_iter NULL
 #endif
 
 /*
@@ -478,6 +498,7 @@ static struct target_type stripe_target = {
 	.io_hints = stripe_io_hints,
 	.direct_access = stripe_dax_direct_access,
 	.dax_copy_from_iter = stripe_dax_copy_from_iter,
+	.dax_copy_to_iter = stripe_dax_copy_to_iter,
 };
 
 int __init dm_stripe_init(void)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 20a8d63754bf..e65429a29c06 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1089,6 +1089,30 @@ static size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
 	return ret;
 }
 
+static size_t dm_dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	long ret = 0;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (!ti->type->dax_copy_to_iter) {
+		ret = copy_to_iter(addr, bytes, i);
+		goto out;
+	}
+	ret = ti->type->dax_copy_to_iter(ti, pgoff, addr, bytes, i);
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
 /*
  * A target may call dm_accept_partial_bio only from the map routine.  It is
  * allowed for all bio types except REQ_PREFLUSH and REQ_OP_ZONE_RESET.
@@ -3137,6 +3161,7 @@ static const struct block_device_operations dm_blk_dops = {
 static const struct dax_operations dm_dax_ops = {
 	.direct_access = dm_dax_direct_access,
 	.copy_from_iter = dm_dax_copy_from_iter,
+	.copy_to_iter = dm_dax_copy_to_iter,
 };
 
 /*
diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index a64023690cad..27902a8799b1 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -100,6 +100,9 @@ static int nvdimm_bus_probe(struct device *dev)
 	if (!try_module_get(provider))
 		return -ENXIO;
 
+	dev_dbg(&nvdimm_bus->dev, "START: %s.probe(%s)\n",
+			dev->driver->name, dev_name(dev));
+
 	nvdimm_bus_probe_start(nvdimm_bus);
 	rc = nd_drv->probe(dev);
 	if (rc == 0)
@@ -108,7 +111,7 @@ static int nvdimm_bus_probe(struct device *dev)
 		nd_region_disable(nvdimm_bus, dev);
 	nvdimm_bus_probe_end(nvdimm_bus);
 
-	dev_dbg(&nvdimm_bus->dev, "%s.probe(%s) = %d\n", dev->driver->name,
+	dev_dbg(&nvdimm_bus->dev, "END: %s.probe(%s) = %d\n", dev->driver->name,
 			dev_name(dev), rc);
 
 	if (rc != 0)
@@ -566,14 +569,18 @@ int nvdimm_revalidate_disk(struct gendisk *disk)
 {
 	struct device *dev = disk_to_dev(disk)->parent;
 	struct nd_region *nd_region = to_nd_region(dev->parent);
-	const char *pol = nd_region->ro ? "only" : "write";
+	int disk_ro = get_disk_ro(disk);
 
-	if (nd_region->ro == get_disk_ro(disk))
+	/*
+	 * Upgrade to read-only if the region is read-only preserve as
+	 * read-only if the disk is already read-only.
+	 */
+	if (disk_ro || nd_region->ro == disk_ro)
 		return 0;
 
-	dev_info(dev, "%s read-%s, marking %s read-%s\n",
-			dev_name(&nd_region->dev), pol, disk->disk_name, pol);
-	set_disk_ro(disk, nd_region->ro);
+	dev_info(dev, "%s read-only, marking %s read-only\n",
+			dev_name(&nd_region->dev), disk->disk_name);
+	set_disk_ro(disk, 1);
 
 	return 0;
 
diff --git a/drivers/nvdimm/e820.c b/drivers/nvdimm/e820.c
index 6f9a6ffd7cde..521eaf53a52a 100644
--- a/drivers/nvdimm/e820.c
+++ b/drivers/nvdimm/e820.c
@@ -38,12 +38,27 @@ static int e820_range_to_nid(resource_size_t addr)
 }
 #endif
 
+static int e820_register_one(struct resource *res, void *data)
+{
+	struct nd_region_desc ndr_desc;
+	struct nvdimm_bus *nvdimm_bus = data;
+
+	memset(&ndr_desc, 0, sizeof(ndr_desc));
+	ndr_desc.res = res;
+	ndr_desc.attr_groups = e820_pmem_region_attribute_groups;
+	ndr_desc.numa_node = e820_range_to_nid(res->start);
+	set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
+	if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
+		return -ENXIO;
+	return 0;
+}
+
 static int e820_pmem_probe(struct platform_device *pdev)
 {
 	static struct nvdimm_bus_descriptor nd_desc;
 	struct device *dev = &pdev->dev;
 	struct nvdimm_bus *nvdimm_bus;
-	struct resource *p;
+	int rc = -ENXIO;
 
 	nd_desc.attr_groups = e820_pmem_attribute_groups;
 	nd_desc.provider_name = "e820";
@@ -53,27 +68,15 @@ static int e820_pmem_probe(struct platform_device *pdev)
 		goto err;
 	platform_set_drvdata(pdev, nvdimm_bus);
 
-	for (p = iomem_resource.child; p ; p = p->sibling) {
-		struct nd_region_desc ndr_desc;
-
-		if (p->desc != IORES_DESC_PERSISTENT_MEMORY_LEGACY)
-			continue;
-
-		memset(&ndr_desc, 0, sizeof(ndr_desc));
-		ndr_desc.res = p;
-		ndr_desc.attr_groups = e820_pmem_region_attribute_groups;
-		ndr_desc.numa_node = e820_range_to_nid(p->start);
-		set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
-		if (!nvdimm_pmem_region_create(nvdimm_bus, &ndr_desc))
-			goto err;
-	}
-
+	rc = walk_iomem_res_desc(IORES_DESC_PERSISTENT_MEMORY_LEGACY,
+			IORESOURCE_MEM, 0, -1, nvdimm_bus, e820_register_one);
+	if (rc)
+		goto err;
 	return 0;
-
- err:
+err:
 	nvdimm_bus_unregister(nvdimm_bus);
 	dev_err(dev, "failed to register legacy persistent memory ranges\n");
-	return -ENXIO;
+	return rc;
 }
 
 static struct platform_driver e820_pmem_driver = {
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 30b08791597d..3f7ad5bc443e 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -561,8 +561,6 @@ static int __nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
 	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 -EINVAL;
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index e023d6aa22b5..68940356cad3 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -164,11 +164,6 @@ static blk_status_t pmem_do_bvec(struct pmem_device *pmem, struct page *page,
 	return rc;
 }
 
-/* account for REQ_FLUSH rename, replace with REQ_PREFLUSH after v4.8-rc1 */
-#ifndef REQ_FLUSH
-#define REQ_FLUSH REQ_PREFLUSH
-#endif
-
 static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
 {
 	blk_status_t rc = 0;
@@ -179,7 +174,7 @@ static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
 	struct pmem_device *pmem = q->queuedata;
 	struct nd_region *nd_region = to_region(pmem);
 
-	if (bio->bi_opf & REQ_FLUSH)
+	if (bio->bi_opf & REQ_PREFLUSH)
 		nvdimm_flush(nd_region);
 
 	do_acct = nd_iostat_start(bio, &start);
@@ -264,9 +259,16 @@ static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
 	return copy_from_iter_flushcache(addr, bytes, i);
 }
 
+static size_t pmem_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	return copy_to_iter_mcsafe(addr, bytes, i);
+}
+
 static const struct dax_operations pmem_dax_ops = {
 	.direct_access = pmem_dax_direct_access,
 	.copy_from_iter = pmem_copy_from_iter,
+	.copy_to_iter = pmem_copy_to_iter,
 };
 
 static const struct attribute_group *pmem_attribute_groups[] = {
@@ -294,12 +296,33 @@ static void pmem_release_disk(void *__pmem)
 	put_disk(pmem->disk);
 }
 
+static void pmem_release_pgmap_ops(void *__pgmap)
+{
+	dev_pagemap_put_ops();
+}
+
+static void fsdax_pagefree(struct page *page, void *data)
+{
+	wake_up_var(&page->_refcount);
+}
+
+static int setup_pagemap_fsdax(struct device *dev, struct dev_pagemap *pgmap)
+{
+	dev_pagemap_get_ops();
+	if (devm_add_action_or_reset(dev, pmem_release_pgmap_ops, pgmap))
+		return -ENOMEM;
+	pgmap->type = MEMORY_DEVICE_FS_DAX;
+	pgmap->page_free = fsdax_pagefree;
+
+	return 0;
+}
+
 static int pmem_attach_disk(struct device *dev,
 		struct nd_namespace_common *ndns)
 {
 	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
 	struct nd_region *nd_region = to_nd_region(dev->parent);
-	int nid = dev_to_node(dev), fua, wbc;
+	int nid = dev_to_node(dev), fua;
 	struct resource *res = &nsio->res;
 	struct resource bb_res;
 	struct nd_pfn *nd_pfn = NULL;
@@ -335,7 +358,6 @@ static int pmem_attach_disk(struct device *dev,
 		dev_warn(dev, "unable to guarantee persistence of writes\n");
 		fua = 0;
 	}
-	wbc = nvdimm_has_cache(nd_region);
 
 	if (!devm_request_mem_region(dev, res->start, resource_size(res),
 				dev_name(&ndns->dev))) {
@@ -353,6 +375,8 @@ static int pmem_attach_disk(struct device *dev,
 	pmem->pfn_flags = PFN_DEV;
 	pmem->pgmap.ref = &q->q_usage_counter;
 	if (is_nd_pfn(dev)) {
+		if (setup_pagemap_fsdax(dev, &pmem->pgmap))
+			return -ENOMEM;
 		addr = devm_memremap_pages(dev, &pmem->pgmap);
 		pfn_sb = nd_pfn->pfn_sb;
 		pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);
@@ -364,6 +388,8 @@ static int pmem_attach_disk(struct device *dev,
 	} else if (pmem_should_map_pages(dev)) {
 		memcpy(&pmem->pgmap.res, &nsio->res, sizeof(pmem->pgmap.res));
 		pmem->pgmap.altmap_valid = false;
+		if (setup_pagemap_fsdax(dev, &pmem->pgmap))
+			return -ENOMEM;
 		addr = devm_memremap_pages(dev, &pmem->pgmap);
 		pmem->pfn_flags |= PFN_MAP;
 		memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));
@@ -382,7 +408,7 @@ static int pmem_attach_disk(struct device *dev,
 		return PTR_ERR(addr);
 	pmem->virt_addr = addr;
 
-	blk_queue_write_cache(q, wbc, fua);
+	blk_queue_write_cache(q, true, fua);
 	blk_queue_make_request(q, pmem_make_request);
 	blk_queue_physical_block_size(q, PAGE_SIZE);
 	blk_queue_logical_block_size(q, pmem_sector_size(ndns));
@@ -413,7 +439,7 @@ static int pmem_attach_disk(struct device *dev,
 		put_disk(disk);
 		return -ENOMEM;
 	}
-	dax_write_cache(dax_dev, wbc);
+	dax_write_cache(dax_dev, nvdimm_has_cache(nd_region));
 	pmem->dax_dev = dax_dev;
 
 	gendev = disk_to_dev(disk);
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index a612be6f019d..ec3543b83330 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1132,7 +1132,8 @@ EXPORT_SYMBOL_GPL(nvdimm_has_flush);
 
 int nvdimm_has_cache(struct nd_region *nd_region)
 {
-	return is_nd_pmem(&nd_region->dev);
+	return is_nd_pmem(&nd_region->dev) &&
+		!test_bit(ND_REGION_PERSIST_CACHE, &nd_region->flags);
 }
 EXPORT_SYMBOL_GPL(nvdimm_has_cache);
 
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 0a312e450207..29024492b8ed 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -51,9 +51,16 @@ static size_t dcssblk_dax_copy_from_iter(struct dax_device *dax_dev,
 	return copy_from_iter(addr, bytes, i);
 }
 
+static size_t dcssblk_dax_copy_to_iter(struct dax_device *dax_dev,
+		pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
+{
+	return copy_to_iter(addr, bytes, i);
+}
+
 static const struct dax_operations dcssblk_dax_ops = {
 	.direct_access = dcssblk_dax_direct_access,
 	.copy_from_iter = dcssblk_dax_copy_from_iter,
+	.copy_to_iter = dcssblk_dax_copy_to_iter,
 };
 
 struct dcssblk_dev_info {