libnvdimm, pmem: allow nfit_test to override pmem_direct_access()

Currently phys_to_pfn_t() is an exported symbol to allow nfit_test to
override it and indicate that nfit_test-pmem is not device-mapped. Now,
we want to enable nfit_test to operate without DMA_CMA and the pmem it
provides will no longer be physically contiguous, i.e. won't be capable
of supporting direct_access requests larger than a page. Make
pmem_direct_access() a weak symbol so that it can be replaced by the
tools/testing/nvdimm/ version, and move phys_to_pfn_t() to a static
inline now that it no longer needs to be overridden.

Acked-by: Johannes Thumshirn <[e-mail]>
Signed-off-by: Dan Williams <[e-mail]>

drivers/nvdimm/pmem.c

···
 #include <linux/slab.h>
 #include <linux/pmem.h>
 #include <linux/nd.h>
+#include "pmem.h"
 #include "pfn.h"
 #include "nd.h"
-
-struct pmem_device {
-	/* One contiguous memory region per device */
-	phys_addr_t		phys_addr;
-	/* when non-zero this device is hosting a 'pfn' instance */
-	phys_addr_t		data_offset;
-	u64			pfn_flags;
-	void __pmem		*virt_addr;
-	/* immutable base size of the namespace */
-	size_t			size;
-	/* trim size when namespace capacity has been section aligned */
-	u32			pfn_pad;
-	struct badblocks	bb;
-};
 
 static void pmem_clear_poison(struct pmem_device *pmem, phys_addr_t offset,
 		unsigned int len)
···
 	return rc;
 }
 
-static long pmem_direct_access(struct block_device *bdev, sector_t sector,
+/* see "strong" declaration in tools/testing/nvdimm/pmem-dax.c */
+__weak long pmem_direct_access(struct block_device *bdev, sector_t sector,
 		      void __pmem **kaddr, pfn_t *pfn, long size)
 {
 	struct pmem_device *pmem = bdev->bd_queue->queuedata;

drivers/nvdimm/pmem.h

···
+#ifndef __NVDIMM_PMEM_H__
+#define __NVDIMM_PMEM_H__
+#include <linux/badblocks.h>
+#include <linux/types.h>
+#include <linux/pfn_t.h>
+#include <linux/fs.h>
+
+long pmem_direct_access(struct block_device *bdev, sector_t sector,
+		      void __pmem **kaddr, pfn_t *pfn, long size);
+/* this definition is in it's own header for tools/testing/nvdimm to consume */
+struct pmem_device {
+	/* One contiguous memory region per device */
+	phys_addr_t		phys_addr;
+	/* when non-zero this device is hosting a 'pfn' instance */
+	phys_addr_t		data_offset;
+	u64			pfn_flags;
+	void __pmem		*virt_addr;
+	/* immutable base size of the namespace */
+	size_t			size;
+	/* trim size when namespace capacity has been section aligned */
+	u32			pfn_pad;
+	struct badblocks	bb;
+};
+#endif /* __NVDIMM_PMEM_H__ */

include/linux/pfn_t.h

···
 	return __pfn_to_pfn_t(pfn, 0);
 }
 
-extern pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags);
+static inline pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags)
+{
+	return __pfn_to_pfn_t(addr >> PAGE_SHIFT, flags);
+}
 
 static inline bool pfn_t_has_page(pfn_t pfn)
 {

kernel/memremap.c

···
 }
 EXPORT_SYMBOL(devm_memunmap);
 
-pfn_t phys_to_pfn_t(phys_addr_t addr, u64 flags)
-{
-	return __pfn_to_pfn_t(addr >> PAGE_SHIFT, flags);
-}
-EXPORT_SYMBOL(phys_to_pfn_t);
-
 #ifdef CONFIG_ZONE_DEVICE
 static DEFINE_MUTEX(pgmap_lock);
 static RADIX_TREE(pgmap_radix, GFP_KERNEL);

tools/testing/nvdimm/Kbuild

···
 ldflags-y += --wrap=__request_region
 ldflags-y += --wrap=__release_region
 ldflags-y += --wrap=devm_memremap_pages
-ldflags-y += --wrap=phys_to_pfn_t
 
 DRIVERS := ../../../drivers
 NVDIMM_SRC := $(DRIVERS)/nvdimm
 ACPI_SRC := $(DRIVERS)/acpi
 DAX_SRC := $(DRIVERS)/dax
+ccflags-y := -I$(src)/$(NVDIMM_SRC)/
 
 obj-$(CONFIG_LIBNVDIMM) += libnvdimm.o
 obj-$(CONFIG_BLK_DEV_PMEM) += nd_pmem.o
···
 nfit-y += config_check.o
 
 nd_pmem-y := $(NVDIMM_SRC)/pmem.o
+nd_pmem-y += pmem-dax.o
 nd_pmem-y += config_check.o
 
 nd_btt-y := $(NVDIMM_SRC)/btt.o

tools/testing/nvdimm/pmem-dax.c

···
+/*
+ * Copyright (c) 2014-2016, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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 "test/nfit_test.h"
+#include <linux/blkdev.h>
+#include <pmem.h>
+#include <nd.h>
+
+long pmem_direct_access(struct block_device *bdev, sector_t sector,
+		void __pmem **kaddr, pfn_t *pfn, long size)
+{
+	struct pmem_device *pmem = bdev->bd_queue->queuedata;
+	resource_size_t offset = sector * 512 + pmem->data_offset;
+
+	/* disable DAX for nfit_test pmem devices */
+	if (get_nfit_res(pmem->phys_addr + offset)) {
+		dev_info_once(pmem->bb.dev, "dax is disabled for nfit_test\n");
+		return -EIO;
+	}
+
+	if (unlikely(is_bad_pmem(&pmem->bb, sector, size)))
+		return -EIO;
+	*kaddr = pmem->virt_addr + offset;
+	*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
+
+	/*
+	 * If badblocks are present, limit known good range to the
+	 * requested range.
+	 */
+	if (unlikely(pmem->bb.count))
+		return size;
+	return pmem->size - pmem->pfn_pad - offset;
+}

tools/testing/nvdimm/test/iomap.c

···
 	return NULL;
 }
 
-static struct nfit_test_resource *get_nfit_res(resource_size_t resource)
+struct nfit_test_resource *get_nfit_res(resource_size_t resource)
 {
 	struct nfit_test_resource *res;
 
···
 
 	return res;
 }
+EXPORT_SYMBOL(get_nfit_res);
 
 void __iomem *__nfit_test_ioremap(resource_size_t offset, unsigned long size,
 		void __iomem *(*fallback_fn)(resource_size_t, unsigned long))

tools/testing/nvdimm/test/nfit_test.h

···
  */
 #ifndef __NFIT_TEST_H__
 #define __NFIT_TEST_H__
+#include <linux/list.h>
 
 struct nfit_test_resource {
 	struct list_head list;
···
 void __wrap_iounmap(volatile void __iomem *addr);
 void nfit_test_setup(nfit_test_lookup_fn lookup);
 void nfit_test_teardown(void);
+struct nfit_test_resource *get_nfit_res(resource_size_t resource);
 #endif