[linux-block.git] / drivers / dax / super.c

/*
 * 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);
Commit	Line	Data
7b6be844 DW	1	/*
	2	* Copyright(c) 2017 Intel Corporation. All rights reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of version 2 of the GNU General Public License as
	6	* published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful, but
	9	* WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	11	* General Public License for more details.
	12	*/
	13	#include <linux/pagemap.h>
	14	#include <linux/module.h>
	15	#include <linux/mount.h>
	16	#include <linux/magic.h>
	17	#include <linux/cdev.h>
	18	#include <linux/hash.h>
	19	#include <linux/slab.h>
6568b08b	20	#include <linux/dax.h>
7b6be844 DW	21	#include <linux/fs.h>
	22
	23	static int nr_dax = CONFIG_NR_DEV_DAX;
	24	module_param(nr_dax, int, S_IRUGO);
	25	MODULE_PARM_DESC(nr_dax, "max number of dax device instances");
	26
	27	static dev_t dax_devt;
	28	DEFINE_STATIC_SRCU(dax_srcu);
	29	static struct vfsmount *dax_mnt;
	30	static DEFINE_IDA(dax_minor_ida);
	31	static struct kmem_cache *dax_cache __read_mostly;
	32	static struct super_block *dax_superblock __read_mostly;
	33
72058005 DW	34	#define DAX_HASH_SIZE (PAGE_SIZE / sizeof(struct hlist_head))
	35	static struct hlist_head dax_host_list[DAX_HASH_SIZE];
	36	static DEFINE_SPINLOCK(dax_host_lock);
	37
7b6be844 DW	38	int dax_read_lock(void)
	39	{
	40	return srcu_read_lock(&dax_srcu);
	41	}
	42	EXPORT_SYMBOL_GPL(dax_read_lock);
	43
	44	void dax_read_unlock(int id)
	45	{
	46	srcu_read_unlock(&dax_srcu, id);
	47	}
	48	EXPORT_SYMBOL_GPL(dax_read_unlock);
	49
	50	/**
	51	* struct dax_device - anchor object for dax services
	52	* @inode: core vfs
	53	* @cdev: optional character interface for "device dax"
72058005	54	* @host: optional name for lookups where the device path is not available
7b6be844 DW	55	* @private: dax driver private data
	56	* @alive: !alive + rcu grace period == no new operations / mappings
	57	*/
	58	struct dax_device {
72058005	59	struct hlist_node list;
7b6be844 DW	60	struct inode inode;
7b6be844 DW	61	struct cdev cdev;
72058005	62	const char *host;
7b6be844 DW	63	void *private;
7b6be844 DW	64	bool alive;
6568b08b	65	const struct dax_operations *ops;
7b6be844 DW	66	};
7b6be844 DW	67
b0686260 DW	68	/**
	69	* dax_direct_access() - translate a device pgoff to an absolute pfn
	70	* @dax_dev: a dax_device instance representing the logical memory range
	71	* @pgoff: offset in pages from the start of the device to translate
	72	* @nr_pages: number of consecutive pages caller can handle relative to @pfn
	73	* @kaddr: output parameter that returns a virtual address mapping of pfn
	74	* @pfn: output parameter that returns an absolute pfn translation of @pgoff
	75	*
	76	* Return: negative errno if an error occurs, otherwise the number of
	77	* pages accessible at the device relative @pgoff.
	78	*/
	79	long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
	80	void *kaddr, pfn_t pfn)
	81	{
	82	long avail;
	83
	84	/*
	85	* The device driver is allowed to sleep, in order to make the
	86	* memory directly accessible.
	87	*/
	88	might_sleep();
	89
	90	if (!dax_dev)
	91	return -EOPNOTSUPP;
	92
	93	if (!dax_alive(dax_dev))
	94	return -ENXIO;
	95
	96	if (nr_pages < 0)
	97	return nr_pages;
	98
	99	avail = dax_dev->ops->direct_access(dax_dev, pgoff, nr_pages,
	100	kaddr, pfn);
	101	if (!avail)
	102	return -ERANGE;
	103	return min(avail, nr_pages);
	104	}
	105	EXPORT_SYMBOL_GPL(dax_direct_access);
	106
7b6be844 DW	107	bool dax_alive(struct dax_device *dax_dev)
	108	{
	109	lockdep_assert_held(&dax_srcu);
	110	return dax_dev->alive;
	111	}
	112	EXPORT_SYMBOL_GPL(dax_alive);
	113
72058005 DW	114	static int dax_host_hash(const char *host)
	115	{
	116	return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE;
	117	}
	118
7b6be844 DW	119	/*
	120	* Note, rcu is not protecting the liveness of dax_dev, rcu is ensuring
	121	* that any fault handlers or operations that might have seen
	122	* dax_alive(), have completed. Any operations that start after
	123	* synchronize_srcu() has run will abort upon seeing !dax_alive().
	124	*/
	125	void kill_dax(struct dax_device *dax_dev)
	126	{
	127	if (!dax_dev)
	128	return;
	129
	130	dax_dev->alive = false;
72058005	131
7b6be844	132	synchronize_srcu(&dax_srcu);
72058005 DW	133
	134	spin_lock(&dax_host_lock);
	135	hlist_del_init(&dax_dev->list);
	136	spin_unlock(&dax_host_lock);
	137
7b6be844 DW	138	dax_dev->private = NULL;
	139	}
	140	EXPORT_SYMBOL_GPL(kill_dax);
	141
	142	static struct inode dax_alloc_inode(struct super_block sb)
	143	{
	144	struct dax_device *dax_dev;
	145
	146	dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL);
	147	return &dax_dev->inode;
	148	}
	149
	150	static struct dax_device to_dax_dev(struct inode inode)
	151	{
	152	return container_of(inode, struct dax_device, inode);
	153	}
	154
	155	static void dax_i_callback(struct rcu_head *head)
	156	{
	157	struct inode *inode = container_of(head, struct inode, i_rcu);
	158	struct dax_device *dax_dev = to_dax_dev(inode);
	159
72058005 DW	160	kfree(dax_dev->host);
72058005 DW	161	dax_dev->host = NULL;
7b6be844 DW	162	ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev));
	163	kmem_cache_free(dax_cache, dax_dev);
	164	}
	165
	166	static void dax_destroy_inode(struct inode *inode)
	167	{
	168	struct dax_device *dax_dev = to_dax_dev(inode);
	169
	170	WARN_ONCE(dax_dev->alive,
	171	"kill_dax() must be called before final iput()\n");
	172	call_rcu(&inode->i_rcu, dax_i_callback);
	173	}
	174
	175	static const struct super_operations dax_sops = {
	176	.statfs = simple_statfs,
	177	.alloc_inode = dax_alloc_inode,
	178	.destroy_inode = dax_destroy_inode,
	179	.drop_inode = generic_delete_inode,
	180	};
	181
	182	static struct dentry dax_mount(struct file_system_type fs_type,
	183	int flags, const char dev_name, void data)
	184	{
	185	return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC);
	186	}
	187
	188	static struct file_system_type dax_fs_type = {
	189	.name = "dax",
	190	.mount = dax_mount,
	191	.kill_sb = kill_anon_super,
	192	};
	193
	194	static int dax_test(struct inode inode, void data)
	195	{
	196	dev_t devt = (dev_t ) data;
	197
	198	return inode->i_rdev == devt;
	199	}
	200
	201	static int dax_set(struct inode inode, void data)
	202	{
	203	dev_t devt = (dev_t ) data;
	204
	205	inode->i_rdev = devt;
	206	return 0;
	207	}
	208
	209	static struct dax_device *dax_dev_get(dev_t devt)
	210	{
	211	struct dax_device *dax_dev;
	212	struct inode *inode;
	213
	214	inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
	215	dax_test, dax_set, &devt);
	216
	217	if (!inode)
	218	return NULL;
	219
	220	dax_dev = to_dax_dev(inode);
	221	if (inode->i_state & I_NEW) {
	222	dax_dev->alive = true;
	223	inode->i_cdev = &dax_dev->cdev;
	224	inode->i_mode = S_IFCHR;
	225	inode->i_flags = S_DAX;
226	mapping_set_gfp_mask(&inode->i_data, GFP_USER);
227	unlock_new_inode(inode);
228	}
229
230	return dax_dev;
231	}
232
72058005 DW	233	static void dax_add_host(struct dax_device dax_dev, const char host)
	234	{
	235	int hash;
	236
	237	/*
	238	* Unconditionally init dax_dev since it's coming from a
	239	* non-zeroed slab cache
	240	*/
	241	INIT_HLIST_NODE(&dax_dev->list);
	242	dax_dev->host = host;
	243	if (!host)
	244	return;
	245
	246	hash = dax_host_hash(host);
	247	spin_lock(&dax_host_lock);
	248	hlist_add_head(&dax_dev->list, &dax_host_list[hash]);
	249	spin_unlock(&dax_host_lock);
	250	}
	251
6568b08b DW	252	struct dax_device alloc_dax(void private, const char *__host,
6568b08b DW	253	const struct dax_operations *ops)
7b6be844 DW	254	{
7b6be844 DW	255	struct dax_device *dax_dev;
72058005	256	const char *host;
7b6be844 DW	257	dev_t devt;
	258	int minor;
	259
72058005 DW	260	host = kstrdup(__host, GFP_KERNEL);
	261	if (__host && !host)
	262	return NULL;
	263
7b6be844 DW	264	minor = ida_simple_get(&dax_minor_ida, 0, nr_dax, GFP_KERNEL);
7b6be844 DW	265	if (minor < 0)
72058005	266	goto err_minor;
7b6be844 DW	267
	268	devt = MKDEV(MAJOR(dax_devt), minor);
	269	dax_dev = dax_dev_get(devt);
	270	if (!dax_dev)
72058005	271	goto err_dev;
7b6be844	272
72058005	273	dax_add_host(dax_dev, host);
6568b08b	274	dax_dev->ops = ops;
7b6be844 DW	275	dax_dev->private = private;
	276	return dax_dev;
	277
72058005	278	err_dev:
7b6be844	279	ida_simple_remove(&dax_minor_ida, minor);
72058005 DW	280	err_minor:
72058005 DW	281	kfree(host);
7b6be844 DW	282	return NULL;
	283	}
	284	EXPORT_SYMBOL_GPL(alloc_dax);
	285
	286	void put_dax(struct dax_device *dax_dev)
	287	{
	288	if (!dax_dev)
	289	return;
	290	iput(&dax_dev->inode);
	291	}
	292	EXPORT_SYMBOL_GPL(put_dax);
	293
72058005 DW	294	/**
	295	* dax_get_by_host() - temporary lookup mechanism for filesystem-dax
	296	* @host: alternate name for the device registered by a dax driver
	297	*/
	298	struct dax_device dax_get_by_host(const char host)
	299	{
	300	struct dax_device dax_dev, found = NULL;
	301	int hash, id;
	302
	303	if (!host)
	304	return NULL;
	305
	306	hash = dax_host_hash(host);
	307
	308	id = dax_read_lock();
	309	spin_lock(&dax_host_lock);
	310	hlist_for_each_entry(dax_dev, &dax_host_list[hash], list) {
	311	if (!dax_alive(dax_dev)
	312	\|\| strcmp(host, dax_dev->host) != 0)
	313	continue;
	314
	315	if (igrab(&dax_dev->inode))
	316	found = dax_dev;
	317	break;
	318	}
	319	spin_unlock(&dax_host_lock);
	320	dax_read_unlock(id);
	321
	322	return found;
	323	}
	324	EXPORT_SYMBOL_GPL(dax_get_by_host);
	325
7b6be844 DW	326	/**
	327	* inode_dax: convert a public inode into its dax_dev
	328	* @inode: An inode with i_cdev pointing to a dax_dev
	329	*
	330	* Note this is not equivalent to to_dax_dev() which is for private
	331	* internal use where we know the inode filesystem type == dax_fs_type.
	332	*/
	333	struct dax_device inode_dax(struct inode inode)
	334	{
	335	struct cdev *cdev = inode->i_cdev;
	336
	337	return container_of(cdev, struct dax_device, cdev);
	338	}
	339	EXPORT_SYMBOL_GPL(inode_dax);
	340
	341	struct inode dax_inode(struct dax_device dax_dev)
	342	{
	343	return &dax_dev->inode;
	344	}
	345	EXPORT_SYMBOL_GPL(dax_inode);
	346
	347	void dax_get_private(struct dax_device dax_dev)
	348	{
	349	return dax_dev->private;
	350	}
	351	EXPORT_SYMBOL_GPL(dax_get_private);
	352
	353	static void init_once(void *_dax_dev)
	354	{
	355	struct dax_device *dax_dev = _dax_dev;
	356	struct inode *inode = &dax_dev->inode;
	357
	358	inode_init_once(inode);
	359	}
	360
	361	static int __dax_fs_init(void)
	362	{
	363	int rc;
	364
	365	dax_cache = kmem_cache_create("dax_cache", sizeof(struct dax_device), 0,
	366	(SLAB_HWCACHE_ALIGN\|SLAB_RECLAIM_ACCOUNT\|
	367	SLAB_MEM_SPREAD\|SLAB_ACCOUNT),
	368	init_once);
	369	if (!dax_cache)
	370	return -ENOMEM;
	371
	372	rc = register_filesystem(&dax_fs_type);
	373	if (rc)
	374	goto err_register_fs;
	375
	376	dax_mnt = kern_mount(&dax_fs_type);
	377	if (IS_ERR(dax_mnt)) {
	378	rc = PTR_ERR(dax_mnt);
	379	goto err_mount;
	380	}
	381	dax_superblock = dax_mnt->mnt_sb;
	382
	383	return 0;
	384
	385	err_mount:
	386	unregister_filesystem(&dax_fs_type);
	387	err_register_fs:
	388	kmem_cache_destroy(dax_cache);
	389
390	return rc;
391	}
392
393	static void __dax_fs_exit(void)
394	{
395	kern_unmount(dax_mnt);
396	unregister_filesystem(&dax_fs_type);
397	kmem_cache_destroy(dax_cache);
398	}
399
400	static int __init dax_fs_init(void)
401	{
402	int rc;
403
404	rc = __dax_fs_init();
405	if (rc)
406	return rc;
407
408	nr_dax = max(nr_dax, 256);
409	rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax");
410	if (rc)
411	__dax_fs_exit();
412	return rc;
413	}
414
415	static void __exit dax_fs_exit(void)
416	{
417	unregister_chrdev_region(dax_devt, nr_dax);
418	ida_destroy(&dax_minor_ida);
419	__dax_fs_exit();
420	}
421
422	MODULE_AUTHOR("Intel Corporation");
423	MODULE_LICENSE("GPL v2");
424	subsys_initcall(dax_fs_init);
425	module_exit(dax_fs_exit);