author: Linus Torvalds <torvalds@linux-foundation.org> 2017-05-05 18:49:20 -0700
committer: Linus Torvalds <torvalds@linux-foundation.org> 2017-05-05 18:49:20 -0700
commit: 53ef7d0e208fa38c3f63d287e0c3ab174f1e1235
parent: c6a677c6f37bb7abc85ba7e3465e82b9f7eb1d91
Commit Summary:
Diffstat:
8 files changed, 598 insertions, 341 deletions
diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
index 9e95bf94eb13..b7053eafd88e 100644
--- a/drivers/dax/Kconfig
+++ b/drivers/dax/Kconfig
@@ -1,8 +1,13 @@
-menuconfig DEV_DAX
+menuconfig DAX
tristate "DAX: direct access to differentiated memory"
+ select SRCU
default m if NVDIMM_DAX
+
+if DAX
+
+config DEV_DAX
+ tristate "Device DAX: direct access mapping device"
depends on TRANSPARENT_HUGEPAGE
- select SRCU
help
Support raw access to differentiated (persistence, bandwidth,
latency...) memory via an mmap(2) capable character
@@ -11,7 +16,6 @@ menuconfig DEV_DAX
baseline memory pool. Mappings of a /dev/daxX.Y device impose
restrictions that make the mapping behavior deterministic.
-if DEV_DAX
config DEV_DAX_PMEM
tristate "PMEM DAX: direct access to persistent memory"
diff --git a/drivers/dax/Makefile b/drivers/dax/Makefile
index 27c54e38478a..dc7422530462 100644
--- a/drivers/dax/Makefile
+++ b/drivers/dax/Makefile
@@ -1,4 +1,7 @@
-obj-$(CONFIG_DEV_DAX) += dax.o
+obj-$(CONFIG_DAX) += dax.o
+obj-$(CONFIG_DEV_DAX) += device_dax.o
obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem.o
+dax-y := super.o
dax_pmem-y := pmem.o
+device_dax-y := device.o
diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
new file mode 100644
index 000000000000..b6fc4f04636d
--- /dev/null
+++ b/drivers/dax/dax-private.h
@@ -0,0 +1,57 @@
+/*
+ * Copyright(c) 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.
+ */
+#ifndef __DAX_PRIVATE_H__
+#define __DAX_PRIVATE_H__
+
+#include <linux/device.h>
+#include <linux/cdev.h>
+
+/**
+ * struct dax_region - mapping infrastructure for dax devices
+ * @id: kernel-wide unique region for a memory range
+ * @base: linear address corresponding to @res
+ * @kref: to pin while other agents have a need to do lookups
+ * @dev: parent device backing this region
+ * @align: allocation and mapping alignment for child dax devices
+ * @res: physical address range of the region
+ * @pfn_flags: identify whether the pfns are paged back or not
+ */
+struct dax_region {
+ int id;
+ struct ida ida;
+ void *base;
+ struct kref kref;
+ struct device *dev;
+ unsigned int align;
+ struct resource res;
+ unsigned long pfn_flags;
+};
+
+/**
+ * struct dev_dax - instance data for a subdivision of a dax region
+ * @region - parent region
+ * @dax_dev - core dax functionality
+ * @dev - device core
+ * @id - child id in the region
+ * @num_resources - number of physical address extents in this device
+ * @res - array of physical address ranges
+ */
+struct dev_dax {
+ struct dax_region *region;
+ struct dax_device *dax_dev;
+ struct device dev;
+ int id;
+ int num_resources;
+ struct resource res[0];
+};
+#endif
diff --git a/drivers/dax/dax.h b/drivers/dax/dax.h
index ddd829ab58c0..f9e5feea742c 100644
--- a/drivers/dax/dax.h
+++ b/drivers/dax/dax.h
@@ -1,5 +1,5 @@
/*
- * Copyright(c) 2016 Intel Corporation. All rights reserved.
+ * Copyright(c) 2016 - 2017 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
@@ -12,14 +12,7 @@
*/
#ifndef __DAX_H__
#define __DAX_H__
-struct device;
-struct dax_dev;
-struct resource;
-struct dax_region;
-void dax_region_put(struct dax_region *dax_region);
-struct dax_region *alloc_dax_region(struct device *parent,
- int region_id, struct resource *res, unsigned int align,
- void *addr, unsigned long flags);
-struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
- struct resource *res, int count);
+struct dax_device;
+struct dax_device *inode_dax(struct inode *inode);
+struct inode *dax_inode(struct dax_device *dax_dev);
#endif /* __DAX_H__ */
diff --git a/drivers/dax/device-dax.h b/drivers/dax/device-dax.h
new file mode 100644
index 000000000000..fdcd9769ffde
--- /dev/null
+++ b/drivers/dax/device-dax.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright(c) 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.
+ */
+#ifndef __DEVICE_DAX_H__
+#define __DEVICE_DAX_H__
+struct device;
+struct dev_dax;
+struct resource;
+struct dax_region;
+void dax_region_put(struct dax_region *dax_region);
+struct dax_region *alloc_dax_region(struct device *parent,
+ int region_id, struct resource *res, unsigned int align,
+ void *addr, unsigned long flags);
+struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
+ struct resource *res, int count);
+#endif /* __DEVICE_DAX_H__ */
diff --git a/drivers/dax/dax.c b/drivers/dax/device.c
similarity index 51%
rename from drivers/dax/dax.c
rename to drivers/dax/device.c
index 19795eb35579..006e657dfcb9 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/device.c
@@ -1,5 +1,5 @@
/*
- * Copyright(c) 2016 Intel Corporation. All rights reserved.
+ * Copyright(c) 2016 - 2017 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
@@ -13,100 +13,38 @@
#include <linux/pagemap.h>
#include <linux/module.h>
#include <linux/device.h>
-#include <linux/magic.h>
-#include <linux/mount.h>
#include <linux/pfn_t.h>
-#include <linux/hash.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/dax.h>
#include <linux/fs.h>
#include <linux/mm.h>
+#include "dax-private.h"
#include "dax.h"
-static dev_t dax_devt;
-DEFINE_STATIC_SRCU(dax_srcu);
static struct class *dax_class;
-static DEFINE_IDA(dax_minor_ida);
-static int nr_dax = CONFIG_NR_DEV_DAX;
-module_param(nr_dax, int, S_IRUGO);
-static struct vfsmount *dax_mnt;
-static struct kmem_cache *dax_cache __read_mostly;
-static struct super_block *dax_superblock __read_mostly;
-MODULE_PARM_DESC(nr_dax, "max number of device-dax instances");
-
-/**
- * struct dax_region - mapping infrastructure for dax devices
- * @id: kernel-wide unique region for a memory range
- * @base: linear address corresponding to @res
- * @kref: to pin while other agents have a need to do lookups
- * @dev: parent device backing this region
- * @align: allocation and mapping alignment for child dax devices
- * @res: physical address range of the region
- * @pfn_flags: identify whether the pfns are paged back or not
- */
-struct dax_region {
- int id;
- struct ida ida;
- void *base;
- struct kref kref;
- struct device *dev;
- unsigned int align;
- struct resource res;
- unsigned long pfn_flags;
-};
-/**
- * struct dax_dev - subdivision of a dax region
- * @region - parent region
- * @dev - device backing the character device
- * @cdev - core chardev data
- * @alive - !alive + srcu grace period == no new mappings can be established
- * @id - child id in the region
- * @num_resources - number of physical address extents in this device
- * @res - array of physical address ranges
+/*
+ * Rely on the fact that drvdata is set before the attributes are
+ * registered, and that the attributes are unregistered before drvdata
+ * is cleared to assume that drvdata is always valid.
*/
-struct dax_dev {
- struct dax_region *region;
- struct inode *inode;
- struct device dev;
- struct cdev cdev;
- bool alive;
- int id;
- int num_resources;
- struct resource res[0];
-};
-
static ssize_t id_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- struct dax_region *dax_region;
- ssize_t rc = -ENXIO;
-
- device_lock(dev);
- dax_region = dev_get_drvdata(dev);
- if (dax_region)
- rc = sprintf(buf, "%d\n", dax_region->id);
- device_unlock(dev);
+ struct dax_region *dax_region = dev_get_drvdata(dev);
- return rc;
+ return sprintf(buf, "%d\n", dax_region->id);
}
static DEVICE_ATTR_RO(id);
static ssize_t region_size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- struct dax_region *dax_region;
- ssize_t rc = -ENXIO;
-
- device_lock(dev);
- dax_region = dev_get_drvdata(dev);
- if (dax_region)
- rc = sprintf(buf, "%llu\n", (unsigned long long)
- resource_size(&dax_region->res));
- device_unlock(dev);
+ struct dax_region *dax_region = dev_get_drvdata(dev);
- return rc;
+ return sprintf(buf, "%llu\n", (unsigned long long)
+ resource_size(&dax_region->res));
}
static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
region_size_show, NULL);
@@ -114,16 +52,9 @@ static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
static ssize_t align_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- struct dax_region *dax_region;
- ssize_t rc = -ENXIO;
-
- device_lock(dev);
- dax_region = dev_get_drvdata(dev);
- if (dax_region)
- rc = sprintf(buf, "%u\n", dax_region->align);
- device_unlock(dev);
+ struct dax_region *dax_region = dev_get_drvdata(dev);
- return rc;
+ return sprintf(buf, "%u\n", dax_region->align);
}
static DEVICE_ATTR_RO(align);
@@ -144,117 +75,6 @@ static const struct attribute_group *dax_region_attribute_groups[] = {
NULL,
};
-static struct inode *dax_alloc_inode(struct super_block *sb)
-{
- return kmem_cache_alloc(dax_cache, GFP_KERNEL);
-}
-
-static void dax_i_callback(struct rcu_head *head)
-{
- struct inode *inode = container_of(head, struct inode, i_rcu);
-
- kmem_cache_free(dax_cache, inode);
-}
-
-static void dax_destroy_inode(struct inode *inode)
-{
- call_rcu(&inode->i_rcu, dax_i_callback);
-}
-
-static const struct super_operations dax_sops = {
- .statfs = simple_statfs,
- .alloc_inode = dax_alloc_inode,
- .destroy_inode = dax_destroy_inode,
- .drop_inode = generic_delete_inode,
-};
-
-static struct dentry *dax_mount(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data)
-{
- return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC);
-}
-
-static struct file_system_type dax_type = {
- .name = "dax",
- .mount = dax_mount,
- .kill_sb = kill_anon_super,
-};
-
-static int dax_test(struct inode *inode, void *data)
-{
- return inode->i_cdev == data;
-}
-
-static int dax_set(struct inode *inode, void *data)
-{
- inode->i_cdev = data;
- return 0;
-}
-
-static struct inode *dax_inode_get(struct cdev *cdev, dev_t devt)
-{
- struct inode *inode;
-
- inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
- dax_test, dax_set, cdev);
-
- if (!inode)
- return NULL;
-
- if (inode->i_state & I_NEW) {
- inode->i_mode = S_IFCHR;
- inode->i_flags = S_DAX;
- inode->i_rdev = devt;
- mapping_set_gfp_mask(&inode->i_data, GFP_USER);
- unlock_new_inode(inode);
- }
- return inode;
-}
-
-static void init_once(void *inode)
-{
- inode_init_once(inode);
-}
-
-static int dax_inode_init(void)
-{
- int rc;
-
- dax_cache = kmem_cache_create("dax_cache", sizeof(struct inode), 0,
- (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
- SLAB_MEM_SPREAD|SLAB_ACCOUNT),
- init_once);
- if (!dax_cache)
- return -ENOMEM;
-
- rc = register_filesystem(&dax_type);
- if (rc)
- goto err_register_fs;
-
- dax_mnt = kern_mount(&dax_type);
- if (IS_ERR(dax_mnt)) {
- rc = PTR_ERR(dax_mnt);
- goto err_mount;
- }
- dax_superblock = dax_mnt->mnt_sb;
-
- return 0;
-
- err_mount:
- unregister_filesystem(&dax_type);
- err_register_fs:
- kmem_cache_destroy(dax_cache);
-
- return rc;
-}
-
-static void dax_inode_exit(void)
-{
- kern_unmount(dax_mnt);
- unregister_filesystem(&dax_type);
- kmem_cache_destroy(dax_cache);
-}
-
static void dax_region_free(struct kref *kref)
{
struct dax_region *dax_region;
@@ -323,47 +143,47 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
}
EXPORT_SYMBOL_GPL(alloc_dax_region);
-static struct dax_dev *to_dax_dev(struct device *dev)
+static struct dev_dax *to_dev_dax(struct device *dev)
{
- return container_of(dev, struct dax_dev, dev);
+ return container_of(dev, struct dev_dax, dev);
}
static ssize_t size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- struct dax_dev *dax_dev = to_dax_dev(dev);
+ struct dev_dax *dev_dax = to_dev_dax(dev);
unsigned long long size = 0;
int i;
- for (i = 0; i < dax_dev->num_resources; i++)
- size += resource_size(&dax_dev->res[i]);
+ for (i = 0; i < dev_dax->num_resources; i++)
+ size += resource_size(&dev_dax->res[i]);
return sprintf(buf, "%llu\n", size);
}
static DEVICE_ATTR_RO(size);
-static struct attribute *dax_device_attributes[] = {
+static struct attribute *dev_dax_attributes[] = {
&dev_attr_size.attr,
NULL,
};
-static const struct attribute_group dax_device_attribute_group = {
- .attrs = dax_device_attributes,
+static const struct attribute_group dev_dax_attribute_group = {
+ .attrs = dev_dax_attributes,
};
static const struct attribute_group *dax_attribute_groups[] = {
- &dax_device_attribute_group,
+ &dev_dax_attribute_group,
NULL,
};
-static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma,
+static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
const char *func)
{
- struct dax_region *dax_region = dax_dev->region;
- struct device *dev = &dax_dev->dev;
+ struct dax_region *dax_region = dev_dax->region;
+ struct device *dev = &dev_dax->dev;
unsigned long mask;
- if (!dax_dev->alive)
+ if (!dax_alive(dev_dax->dax_dev))
return -ENXIO;
/* prevent private mappings from being established */
@@ -397,23 +217,24 @@ static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma,
return 0;
}
-static phys_addr_t pgoff_to_phys(struct dax_dev *dax_dev, pgoff_t pgoff,
+/* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
+__weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
unsigned long size)
{
struct resource *res;
phys_addr_t phys;
int i;
- for (i = 0; i < dax_dev->num_resources; i++) {
- res = &dax_dev->res[i];
+ for (i = 0; i < dev_dax->num_resources; i++) {
+ res = &dev_dax->res[i];
phys = pgoff * PAGE_SIZE + res->start;
if (phys >= res->start && phys <= res->end)
break;
pgoff -= PHYS_PFN(resource_size(res));
}
- if (i < dax_dev->num_resources) {
- res = &dax_dev->res[i];
+ if (i < dev_dax->num_resources) {
+ res = &dev_dax->res[i];
if (phys + size - 1 <= res->end)
return phys;
}
@@ -421,28 +242,29 @@ static phys_addr_t pgoff_to_phys(struct dax_dev *dax_dev, pgoff_t pgoff,
return -1;
}
-static int __dax_dev_pte_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
+static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
{
- struct device *dev = &dax_dev->dev;
+ struct device *dev = &dev_dax->dev;
struct dax_region *dax_region;
int rc = VM_FAULT_SIGBUS;
phys_addr_t phys;
pfn_t pfn;
unsigned int fault_size = PAGE_SIZE;
- if (check_vma(dax_dev, vmf->vma, __func__))
+ if (check_vma(dev_dax, vmf->vma, __func__))
return VM_FAULT_SIGBUS;
- dax_region = dax_dev->region;
+ dax_region = dev_dax->region;
if (dax_region->align > PAGE_SIZE) {
- dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+ dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
+ __func__, dax_region->align, fault_size);
return VM_FAULT_SIGBUS;
}
if (fault_size != dax_region->align)
return VM_FAULT_SIGBUS;
- phys = pgoff_to_phys(dax_dev, vmf->pgoff, PAGE_SIZE);
+ phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
if (phys == -1) {
dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
vmf->pgoff);
@@ -461,28 +283,29 @@ static int __dax_dev_pte_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
return VM_FAULT_NOPAGE;
}
-static int __dax_dev_pmd_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
+static int __dev_dax_pmd_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
{
unsigned long pmd_addr = vmf->address & PMD_MASK;
- struct device *dev = &dax_dev->dev;
+ struct device *dev = &dev_dax->dev;
struct dax_region *dax_region;
phys_addr_t phys;
pgoff_t pgoff;
pfn_t pfn;
unsigned int fault_size = PMD_SIZE;
- if (check_vma(dax_dev, vmf->vma, __func__))
+ if (check_vma(dev_dax, vmf->vma, __func__))
return VM_FAULT_SIGBUS;
- dax_region = dax_dev->region;
+ dax_region = dev_dax->region;
if (dax_region->align > PMD_SIZE) {
- dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+ dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
+ __func__, dax_region->align, fault_size);
return VM_FAULT_SIGBUS;
}
/* dax pmd mappings require pfn_t_devmap() */
if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
- dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+ dev_dbg(dev, "%s: region lacks devmap flags\n", __func__);
return VM_FAULT_SIGBUS;
}
@@ -497,7 +320,7 @@ static int __dax_dev_pmd_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
return VM_FAULT_SIGBUS;
pgoff = linear_page_index(vmf->vma, pmd_addr);
- phys = pgoff_to_phys(dax_dev, pgoff, PMD_SIZE);
+ phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
if (phys == -1) {
dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
pgoff);
@@ -511,10 +334,10 @@ static int __dax_dev_pmd_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
}
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
-static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
+static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
{
unsigned long pud_addr = vmf->address & PUD_MASK;
- struct device *dev = &dax_dev->dev;
+ struct device *dev = &dev_dax->dev;
struct dax_region *dax_region;
phys_addr_t phys;
pgoff_t pgoff;
@@ -522,18 +345,19 @@ static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
unsigned int fault_size = PUD_SIZE;
- if (check_vma(dax_dev, vmf->vma, __func__))
+ if (check_vma(dev_dax, vmf->vma, __func__))
return VM_FAULT_SIGBUS;
- dax_region = dax_dev->region;
+ dax_region = dev_dax->region;
if (dax_region->align > PUD_SIZE) {
- dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+ dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
+ __func__, dax_region->align, fault_size);
return VM_FAULT_SIGBUS;
}
/* dax pud mappings require pfn_t_devmap() */
if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
- dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+ dev_dbg(dev, "%s: region lacks devmap flags\n", __func__);
return VM_FAULT_SIGBUS;
}
@@ -548,7 +372,7 @@ static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
return VM_FAULT_SIGBUS;
pgoff = linear_page_index(vmf->vma, pud_addr);
- phys = pgoff_to_phys(dax_dev, pgoff, PUD_SIZE);
+ phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
if (phys == -1) {
dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
pgoff);
@@ -561,65 +385,71 @@ static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
vmf->flags & FAULT_FLAG_WRITE);
}
#else
-static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
+static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
{
return VM_FAULT_FALLBACK;
}
#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
-static int dax_dev_huge_fault(struct vm_fault *vmf,
+static int dev_dax_huge_fault(struct vm_fault *vmf,
enum page_entry_size pe_size)
{
int rc, id;
struct file *filp = vmf->vma->vm_file;
- struct dax_dev *dax_dev = filp->private_data;
+ struct dev_dax *dev_dax = filp->private_data;
- dev_dbg(&dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
+ dev_dbg(&dev_dax->dev, "%s: %s: %s (%#lx - %#lx) size = %d\n", __func__,
current->comm, (vmf->flags & FAULT_FLAG_WRITE)
? "write" : "read",
- vmf->vma->vm_start, vmf->vma->vm_end);
+ vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
- id = srcu_read_lock(&dax_srcu);
+ id = dax_read_lock();
switch (pe_size) {
case PE_SIZE_PTE:
- rc = __dax_dev_pte_fault(dax_dev, vmf);
+ rc = __dev_dax_pte_fault(dev_dax, vmf);
break;
case PE_SIZE_PMD:
- rc = __dax_dev_pmd_fault(dax_dev, vmf);
+ rc = __dev_dax_pmd_fault(dev_dax, vmf);
break;
case PE_SIZE_PUD:
- rc = __dax_dev_pud_fault(dax_dev, vmf);
+ rc = __dev_dax_pud_fault(dev_dax, vmf);
break;
default:
- return VM_FAULT_FALLBACK;
+ rc = VM_FAULT_SIGBUS;
}
- srcu_read_unlock(&dax_srcu, id);
+ dax_read_unlock(id);
return rc;
}
-static int dax_dev_fault(struct vm_fault *vmf)
+static int dev_dax_fault(struct vm_fault *vmf)
{
- return dax_dev_huge_fault(vmf, PE_SIZE_PTE);
+ return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
}
-static const struct vm_operations_struct dax_dev_vm_ops = {
- .fault = dax_dev_fault,
- .huge_fault = dax_dev_huge_fault,
+static const struct vm_operations_struct dax_vm_ops = {
+ .fault = dev_dax_fault,
+ .huge_fault = dev_dax_huge_fault,
};
static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
{
- struct dax_dev *dax_dev = filp->private_data;
- int rc;
+ struct dev_dax *dev_dax = filp->private_data;
+ int rc, id;
- dev_dbg(&dax_dev->dev, "%s\n", __func__);
+ dev_dbg(&dev_dax->dev, "%s\n", __func__);
- rc = check_vma(dax_dev, vma, __func__);
+ /*
+ * We lock to check dax_dev liveness and will re-check at
+ * fault time.
+ */
+ id = dax_read_lock();
+ rc = check_vma(dev_dax, vma, __func__);
+ dax_read_unlock(id);
if (rc)
return rc;
- vma->vm_ops = &dax_dev_vm_ops;
+ vma->vm_ops = &dax_vm_ops;
vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
return 0;
}
@@ -630,13 +460,13 @@ static unsigned long dax_get_unmapped_area(struct file *filp,
unsigned long flags)
{
unsigned long off, off_end, off_align, len_align, addr_align, align;
- struct dax_dev *dax_dev = filp ? filp->private_data : NULL;
+ struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
struct dax_region *dax_region;
- if (!dax_dev || addr)
+ if (!dev_dax || addr)
goto out;
- dax_region = dax_dev->region;
+ dax_region = dev_dax->region;
align = dax_region->align;
off = pgoff << PAGE_SHIFT;
off_end = off + len;
@@ -661,14 +491,15 @@ static unsigned long dax_get_unmapped_area(struct file *filp,
static int dax_open(struct inode *inode, struct file *filp)
{
- struct dax_dev *dax_dev;
+ struct dax_device *dax_dev = inode_dax(inode);
+ struct inode *__dax_inode = dax_inode(dax_dev);
+ struct dev_dax *dev_dax = dax_get_private(dax_dev);
- dax_dev = container_of(inode->i_cdev, struct dax_dev, cdev);
- dev_dbg(&dax_dev->dev, "%s\n", __func__);
- inode->i_mapping = dax_dev->inode->i_mapping;
- inode->i_mapping->host = dax_dev->inode;
+ dev_dbg(&dev_dax->dev, "%s\n", __func__);
+ inode->i_mapping = __dax_inode->i_mapping;
+ inode->i_mapping->host = __dax_inode;
filp->f_mapping = inode->i_mapping;
- filp->private_data = dax_dev;
+ filp->private_data = dev_dax;
inode->i_flags = S_DAX;
return 0;
@@ -676,9 +507,9 @@ static int dax_open(struct inode *inode, struct file *filp)
static int dax_release(struct inode *inode, struct file *filp)
{
- struct dax_dev *dax_dev = filp->private_data;
+ struct dev_dax *dev_dax = filp->private_data;
- dev_dbg(&dax_dev->dev, "%s\n", __func__);
+ dev_dbg(&dev_dax->dev, "%s\n", __func__);
return 0;
}
@@ -691,55 +522,54 @@ static const struct file_operations dax_fops = {
.mmap = dax_mmap,
};
-static void dax_dev_release(struct device *dev)
+static void dev_dax_release(struct device *dev)
{
- struct dax_dev *dax_dev = to_dax_dev(dev);
- struct dax_region *dax_region = dax_dev->region;
+ struct dev_dax *dev_dax = to_dev_dax(dev);
+ struct dax_region *dax_region = dev_dax->region;
+ struct dax_device *dax_dev = dev_dax->dax_dev;
- ida_simple_remove(&dax_region->ida, dax_dev->id);
- ida_simple_remove(&dax_minor_ida, MINOR(dev->devt));
+ ida_simple_remove(&dax_region->ida, dev_dax->id);
dax_region_put(dax_region);
- iput(dax_dev->inode);
- kfree(dax_dev);
+ put_dax(dax_dev);
+ kfree(dev_dax);
}
-static void kill_dax_dev(struct dax_dev *dax_dev)
+static void kill_dev_dax(struct dev_dax *dev_dax)
{
- /*
- * Note, rcu is not protecting the liveness of dax_dev, rcu is
- * ensuring that any fault handlers that might have seen
- * dax_dev->alive == true, have completed. Any fault handlers
- * that start after synchronize_srcu() has started will abort
- * upon seeing dax_dev->alive == false.
- */
- dax_dev->alive = false;
- synchronize_srcu(&dax_srcu);
- unmap_mapping_range(dax_dev->inode->i_mapping, 0, 0, 1);
+ struct dax_device *dax_dev = dev_dax->dax_dev;
+ struct inode *inode = dax_inode(dax_dev);
+
+ kill_dax(dax_dev);
+ unmap_mapping_range(inode->i_mapping, 0, 0, 1);
}
-static void unregister_dax_dev(void *dev)
+static void unregister_dev_dax(void *dev)
{
- struct dax_dev *dax_dev = to_dax_dev(dev);
+ struct dev_dax *dev_dax = to_dev_dax(dev);
+ struct dax_device *dax_dev = dev_dax->dax_dev;
+ struct inode *inode = dax_inode(dax_dev);
+ struct cdev *cdev = inode->i_cdev;
dev_dbg(dev, "%s\n", __func__);
- kill_dax_dev(dax_dev);
- cdev_device_del(&dax_dev->cdev, dev);
+ kill_dev_dax(dev_dax);
+ cdev_device_del(cdev, dev);
put_device(dev);
}
-struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
+struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
struct resource *res, int count)
{
struct device *parent = dax_region->dev;
- struct dax_dev *dax_dev;
- int rc = 0, minor, i;
+ struct dax_device *dax_dev;
+ struct dev_dax *dev_dax;
+ struct inode *inode;
struct device *dev;
struct cdev *cdev;
- dev_t dev_t;
+ int rc = 0, i;
- dax_dev = kzalloc(sizeof(*dax_dev) + sizeof(*res) * count, GFP_KERNEL);
- if (!dax_dev)
+ dev_dax = kzalloc(sizeof(*dev_dax) + sizeof(*res) * count, GFP_KERNEL);
+ if (!dev_dax)
return ERR_PTR(-ENOMEM);
for (i = 0; i < count; i++) {
@@ -749,110 +579,79 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
rc = -EINVAL;
break;
}
- dax_dev->res[i].start = res[i].start;
- dax_dev->res[i].end = res[i].end;
+ dev_dax->res[i].start = res[i].start;
+ dev_dax->res[i].end = res[i].end;
}
if (i < count)
goto err_id;
- dax_dev->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
- if (dax_dev->id < 0) {
- rc = dax_dev->id;
+ dev_dax->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
+ if (dev_dax->id < 0) {
+ rc = dev_dax->id;
goto err_id;
}
- minor = ida_simple_get(&dax_minor_ida, 0, 0, GFP_KERNEL);
- if (minor < 0) {
- rc = minor;
- goto err_minor;
- }
-
- dev_t = MKDEV(MAJOR(dax_devt), minor);
- dev = &dax_dev->dev;
- dax_dev->inode = dax_inode_get(&dax_dev->cdev, dev_t);
- if (!dax_dev->inode) {
- rc = -ENOMEM;
- goto err_inode;
- }
+ /*
+ * No 'host' or dax_operations since there is no access to this
+ * device outside of mmap of the resulting character device.
+ */
+ dax_dev = alloc_dax(dev_dax, NULL, NULL);
+ if (!dax_dev)
+ goto err_dax;
/* from here on we're committed to teardown via dax_dev_release() */
+ dev = &dev_dax->dev;
device_initialize(dev);
- cdev = &dax_dev->cdev;
+ inode = dax_inode(dax_dev);
+ cdev = inode->i_cdev;
cdev_init(cdev, &dax_fops);
cdev->owner = parent->driver->owner;
- dax_dev->num_resources = count;
- dax_dev->alive = true;
- dax_dev->region = dax_region;
+ dev_dax->num_resources = count;
+ dev_dax->dax_dev = dax_dev;
+ dev_dax->region = dax_region;
kref_get(&dax_region->kref);
- dev->devt = dev_t;
+ dev->devt = inode->i_rdev;
dev->class = dax_class;
dev->parent = parent;
dev->groups = dax_attribute_groups;
- dev->release = dax_dev_release;
- dev_set_name(dev, "dax%d.%d", dax_region->id, dax_dev->id);
+ dev->release = dev_dax_release;
+ dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id);
rc = cdev_device_add(cdev, dev);
if (rc) {
- kill_dax_dev(dax_dev);
+ kill_dev_dax(dev_dax);
put_device(dev);
return ERR_PTR(rc);
}
- rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_dev, dev);
+ rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
if (rc)
return ERR_PTR(rc);
- return dax_dev;
+ return dev_dax;
- err_inode:
- ida_simple_remove(&dax_minor_ida, minor);
- err_minor:
- ida_simple_remove(&dax_region->ida, dax_dev->id);
+ err_dax:
+ ida_simple_remove(&dax_region->ida, dev_dax->id);
err_id:
- kfree(dax_dev);
+ kfree(dev_dax);
return ERR_PTR(rc);
}
-EXPORT_SYMBOL_GPL(devm_create_dax_dev);
+EXPORT_SYMBOL_GPL(devm_create_dev_dax);
static int __init dax_init(void)
{
- int rc;
-
- rc = dax_inode_init();
- if (rc)
- return rc;
-
- nr_dax = max(nr_dax, 256);
- rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax");
- if (rc)
- goto err_chrdev;
-
dax_class = class_create(THIS_MODULE, "dax");
- if (IS_ERR(dax_class)) {
- rc = PTR_ERR(dax_class);
- goto err_class;
- }
-
- return 0;
-
- err_class:
- unregister_chrdev_region(dax_devt, nr_dax);
- err_chrdev:
- dax_inode_exit();
- return rc;
+ return PTR_ERR_OR_ZERO(dax_class);
}
static void __exit dax_exit(void)
{
class_destroy(dax_class);
- unregister_chrdev_region(dax_devt, nr_dax);
- ida_destroy(&dax_minor_ida);
- dax_inode_exit();
}
MODULE_AUTHOR("Intel Corporation");
diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index cb0d742fa23f..9f2a0b4fd801 100644
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -16,7 +16,7 @@
#include <linux/pfn_t.h>
#include "../nvdimm/pfn.h"
#include "../nvdimm/nd.h"
-#include "dax.h"
+#include "device-dax.h"
struct dax_pmem {
struct device *dev;
@@ -61,8 +61,8 @@ static int dax_pmem_probe(struct device *dev)
int rc;
void *addr;
struct resource res;
- struct dax_dev *dax_dev;
struct nd_pfn_sb *pfn_sb;
+ struct dev_dax *dev_dax;
struct dax_pmem *dax_pmem;
struct nd_region *nd_region;
struct nd_namespace_io *nsio;
@@ -130,12 +130,12 @@ static int dax_pmem_probe(struct device *dev)
return -ENOMEM;
/* TODO: support for subdividing a dax region... */
- dax_dev = devm_create_dax_dev(dax_region, &res, 1);
+ dev_dax = devm_create_dev_dax(dax_region, &res, 1);
- /* child dax_dev instances now own the lifetime of the dax_region */
+ /* child dev_dax instances now own the lifetime of the dax_region */
dax_region_put(dax_region);
- return PTR_ERR_OR_ZERO(dax_dev);
+ return PTR_ERR_OR_ZERO(dev_dax);
}
static struct nd_device_driver dax_pmem_driver = {
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
new file mode 100644
index 000000000000..465dcd7317d5
--- /dev/null
+++ b/drivers/dax/super.c
@@ -0,0 +1,425 @@
+/*
+ * Copyright(c) 2017 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/pagemap.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/magic.h>
+#include <linux/cdev.h>
+#include <linux/hash.h>
+#include <linux/slab.h>
+#include <linux/dax.h>
+#include <linux/fs.h>
+
+static int nr_dax = CONFIG_NR_DEV_DAX;
+module_param(nr_dax, int, S_IRUGO);
+MODULE_PARM_DESC(nr_dax, "max number of dax device instances");
+
+static dev_t dax_devt;
+DEFINE_STATIC_SRCU(dax_srcu);
+static struct vfsmount *dax_mnt;
+static DEFINE_IDA(dax_minor_ida);
+static struct kmem_cache *dax_cache __read_mostly;
+static struct super_block *dax_superblock __read_mostly;
+
+#define DAX_HASH_SIZE (PAGE_SIZE / sizeof(struct hlist_head))
+static struct hlist_head dax_host_list[DAX_HASH_SIZE];
+static DEFINE_SPINLOCK(dax_host_lock);
+
+int dax_read_lock(void)
+{
+ return srcu_read_lock(&dax_srcu);
+}
+EXPORT_SYMBOL_GPL(dax_read_lock);
+
+void dax_read_unlock(int id)
+{
+ srcu_read_unlock(&dax_srcu, id);
+}
+EXPORT_SYMBOL_GPL(dax_read_unlock);
+
+/**
+ * struct dax_device - anchor object for dax services
+ * @inode: core vfs
+ * @cdev: optional character interface for "device dax"
+ * @host: optional name for lookups where the device path is not available
+ * @private: dax driver private data
+ * @alive: !alive + rcu grace period == no new operations / mappings
+ */
+struct dax_device {
+ struct hlist_node list;
+ struct inode inode;
+ struct cdev cdev;
+ const char *host;
+ void *private;
+ bool alive;
+ const struct dax_operations *ops;
+};
+
+/**
+ * dax_direct_access() - translate a device pgoff to an absolute pfn
+ * @dax_dev: a dax_device instance representing the logical memory range
+ * @pgoff: offset in pages from the start of the device to translate
+ * @nr_pages: number of consecutive pages caller can handle relative to @pfn
+ * @kaddr: output parameter that returns a virtual address mapping of pfn
+ * @pfn: output parameter that returns an absolute pfn translation of @pgoff
+ *
+ * Return: negative errno if an error occurs, otherwise the number of
+ * pages accessible at the device relative @pgoff.
+ */
+long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
+ void **kaddr, pfn_t *pfn)
+{
+ long avail;
+
+ /*
+ * The device driver is allowed to sleep, in order to make the
+ * memory directly accessible.
+ */
+ might_sleep();
+
+ if (!dax_dev)
+ return -EOPNOTSUPP;
+
+ if (!dax_alive(dax_dev))
+ return -ENXIO;
+
+ if (nr_pages < 0)
+ return nr_pages;
+
+ avail = dax_dev->ops->direct_access(dax_dev, pgoff, nr_pages,
+ kaddr, pfn);
+ if (!avail)
+ return -ERANGE;
+ return min(avail, nr_pages);
+}
+EXPORT_SYMBOL_GPL(dax_direct_access);
+
+bool dax_alive(struct dax_device *dax_dev)
+{
+ lockdep_assert_held(&dax_srcu);
+ return dax_dev->alive;
+}
+EXPORT_SYMBOL_GPL(dax_alive);
+
+static int dax_host_hash(const char *host)
+{
+ return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE;
+}
+
+/*
+ * Note, rcu is not protecting the liveness of dax_dev, rcu is ensuring
+ * that any fault handlers or operations that might have seen
+ * dax_alive(), have completed. Any operations that start after
+ * synchronize_srcu() has run will abort upon seeing !dax_alive().
+ */
+void kill_dax(struct dax_device *dax_dev)
+{
+ if (!dax_dev)
+ return;
+
+ dax_dev->alive = false;
+
+ synchronize_srcu(&dax_srcu);
+
+ spin_lock(&dax_host_lock);
+ hlist_del_init(&dax_dev->list);
+ spin_unlock(&dax_host_lock);
+
+ dax_dev->private = NULL;
+}
+EXPORT_SYMBOL_GPL(kill_dax);
+
+static struct inode *dax_alloc_inode(struct super_block *sb)
+{
+ struct dax_device *dax_dev;
+
+ dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL);
+ return &dax_dev->inode;
+}
+
+static struct dax_device *to_dax_dev(struct inode *inode)
+{
+ return container_of(inode, struct dax_device, inode);
+}
+
+static void dax_i_callback(struct rcu_head *head)
+{
+ struct inode *inode = container_of(head, struct inode, i_rcu);
+ struct dax_device *dax_dev = to_dax_dev(inode);
+
+ kfree(dax_dev->host);
+ dax_dev->host = NULL;
+ ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev));
+ kmem_cache_free(dax_cache, dax_dev);
+}
+
+static void dax_destroy_inode(struct inode *inode)
+{
+ struct dax_device *dax_dev = to_dax_dev(inode);
+
+ WARN_ONCE(dax_dev->alive,
+ "kill_dax() must be called before final iput()\n");
+ call_rcu(&inode->i_rcu, dax_i_callback);
+}
+
+static const struct super_operations dax_sops = {
+ .statfs = simple_statfs,
+ .alloc_inode = dax_alloc_inode,
+ .destroy_inode = dax_destroy_inode,
+ .drop_inode = generic_delete_inode,
+};
+
+static struct dentry *dax_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC);
+}
+
+static struct file_system_type dax_fs_type = {
+ .name = "dax",
+ .mount = dax_mount,
+ .kill_sb = kill_anon_super,
+};
+
+static int dax_test(struct inode *inode, void *data)
+{
+ dev_t devt = *(dev_t *) data;
+
+ return inode->i_rdev == devt;
+}
+
+static int dax_set(struct inode *inode, void *data)
+{
+ dev_t devt = *(dev_t *) data;
+
+ inode->i_rdev = devt;
+ return 0;
+}
+
+static struct dax_device *dax_dev_get(dev_t devt)
+{
+ struct dax_device *dax_dev;
+ struct inode *inode;
+
+ inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
+ dax_test, dax_set, &devt);
+
+ if (!inode)
+ return NULL;
+
+ dax_dev = to_dax_dev(inode);
+ if (inode->i_state & I_NEW) {
+ dax_dev->alive = true;
+ inode->i_cdev = &dax_dev->cdev;
+ inode->i_mode = S_IFCHR;
+ inode->i_flags = S_DAX;
+ mapping_set_gfp_mask(&inode->i_data, GFP_USER);
+ unlock_new_inode(inode);
+ }
+
+ return dax_dev;
+}
+
+static void dax_add_host(struct dax_device *dax_dev, const char *host)
+{
+ int hash;
+
+ /*
+ * Unconditionally init dax_dev since it's coming from a
+ * non-zeroed slab cache
+ */
+ INIT_HLIST_NODE(&dax_dev->list);
+ dax_dev->host = host;
+ if (!host)
+ return;
+
+ hash = dax_host_hash(host);
+ spin_lock(&dax_host_lock);
+ hlist_add_head(&dax_dev->list, &dax_host_list[hash]);
+ spin_unlock(&dax_host_lock);
+}
+
+struct dax_device *alloc_dax(void *private, const char *__host,
+ const struct dax_operations *ops)
+{
+ struct dax_device *dax_dev;
+ const char *host;
+ dev_t devt;
+ int minor;
+
+ host = kstrdup(__host, GFP_KERNEL);
+ if (__host && !host)
+ return NULL;
+
+ minor = ida_simple_get(&dax_minor_ida, 0, nr_dax, GFP_KERNEL);
+ if (minor < 0)
+ goto err_minor;
+
+ devt = MKDEV(MAJOR(dax_devt), minor);
+ dax_dev = dax_dev_get(devt);
+ if (!dax_dev)
+ goto err_dev;
+
+ dax_add_host(dax_dev, host);
+ dax_dev->ops = ops;
+ dax_dev->private = private;
+ return dax_dev;
+
+ err_dev:
+ ida_simple_remove(&dax_minor_ida, minor);
+ err_minor:
+ kfree(host);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(alloc_dax);
+
+void put_dax(struct dax_device *dax_dev)
+{
+ if (!dax_dev)
+ return;
+ iput(&dax_dev->inode);
+}
+EXPORT_SYMBOL_GPL(put_dax);
+
+/**
+ * dax_get_by_host() - temporary lookup mechanism for filesystem-dax
+ * @host: alternate name for the device registered by a dax driver
+ */
+struct dax_device *dax_get_by_host(const char *host)
+{
+ struct dax_device *dax_dev, *found = NULL;
+ int hash, id;
+
+ if (!host)
+ return NULL;
+
+ hash = dax_host_hash(host);
+
+ id = dax_read_lock();
+ spin_lock(&dax_host_lock);
+ hlist_for_each_entry(dax_dev, &dax_host_list[hash], list) {
+ if (!dax_alive(dax_dev)
+ || strcmp(host, dax_dev->host) != 0)
+ continue;
+
+ if (igrab(&dax_dev->inode))
+ found = dax_dev;
+ break;
+ }
+ spin_unlock(&dax_host_lock);
+ dax_read_unlock(id);
+
+ return found;
+}
+EXPORT_SYMBOL_GPL(dax_get_by_host);
+
+/**
+ * inode_dax: convert a public inode into its dax_dev
+ * @inode: An inode with i_cdev pointing to a dax_dev
+ *
+ * Note this is not equivalent to to_dax_dev() which is for private
+ * internal use where we know the inode filesystem type == dax_fs_type.
+ */
+struct dax_device *inode_dax(struct inode *inode)
+{
+ struct cdev *cdev = inode->i_cdev;
+
+ return container_of(cdev, struct dax_device, cdev);
+}
+EXPORT_SYMBOL_GPL(inode_dax);
+
+struct inode *dax_inode(struct dax_device *dax_dev)
+{
+ return &dax_dev->inode;
+}
+EXPORT_SYMBOL_GPL(dax_inode);
+
+void *dax_get_private(struct dax_device *dax_dev)
+{
+ return dax_dev->private;
+}
+EXPORT_SYMBOL_GPL(dax_get_private);
+
+static void init_once(void *_dax_dev)
+{
+ struct dax_device *dax_dev = _dax_dev;
+ struct inode *inode = &dax_dev->inode;
+
+ inode_init_once(inode);
+}
+
+static int __dax_fs_init(void)
+{
+ int rc;
+
+ dax_cache = kmem_cache_create("dax_cache", sizeof(struct dax_device), 0,
+ (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
+ SLAB_MEM_SPREAD|SLAB_ACCOUNT),
+ init_once);
+ if (!dax_cache)
+ return -ENOMEM;
+
+ rc = register_filesystem(&dax_fs_type);
+ if (rc)
+ goto err_register_fs;
+
+ dax_mnt = kern_mount(&dax_fs_type);
+ if (IS_ERR(dax_mnt)) {
+ rc = PTR_ERR(dax_mnt);
+ goto err_mount;
+ }
+ dax_superblock = dax_mnt->mnt_sb;
+
+ return 0;
+
+ err_mount:
+ unregister_filesystem(&dax_fs_type);
+ err_register_fs:
+ kmem_cache_destroy(dax_cache);
+
+ return rc;
+}
+
+static void __dax_fs_exit(void)
+{
+ kern_unmount(dax_mnt);
+ unregister_filesystem(&dax_fs_type);
+ kmem_cache_destroy(dax_cache);
+}
+
+static int __init dax_fs_init(void)
+{
+ int rc;
+
+ rc = __dax_fs_init();
+ if (rc)
+ return rc;
+
+ nr_dax = max(nr_dax, 256);
+ rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax");
+ if (rc)
+ __dax_fs_exit();
+ return rc;
+}
+
+static void __exit dax_fs_exit(void)
+{
+ unregister_chrdev_region(dax_devt, nr_dax);
+ ida_destroy(&dax_minor_ida);
+ __dax_fs_exit();
+}
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
+subsys_initcall(dax_fs_init);
+module_exit(dax_fs_exit);