[mirror_ubuntu-artful-kernel.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/genhd.h>
#include <linux/cdev.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/dax.h>
#include <linux/fs.h>

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);

#ifdef CONFIG_BLOCK
int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
		pgoff_t *pgoff)
{
	phys_addr_t phys_off = (get_start_sect(bdev) + sector) * 512;

	if (pgoff)
		*pgoff = PHYS_PFN(phys_off);
	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
		return -EINVAL;
	return 0;
}
EXPORT_SYMBOL(bdev_dax_pgoff);

/**
 * __bdev_dax_supported() - Check if the device supports dax for filesystem
 * @sb: The superblock of the device
 * @blocksize: The block size of the device
 *
 * This is a library function for filesystems to check if the block device
 * can be mounted with dax option.
 *
 * Return: negative errno if unsupported, 0 if supported.
 */
int __bdev_dax_supported(struct super_block *sb, int blocksize)
{
	struct block_device *bdev = sb->s_bdev;
	struct dax_device *dax_dev;
	pgoff_t pgoff;
	int err, id;
	void *kaddr;
	pfn_t pfn;
	long len;

	if (blocksize != PAGE_SIZE) {
		pr_err("VFS (%s): error: unsupported blocksize for dax\n",
				sb->s_id);
		return -EINVAL;
	}

	err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
	if (err) {
		pr_err("VFS (%s): error: unaligned partition for dax\n",
				sb->s_id);
		return err;
	}

	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
	if (!dax_dev) {
		pr_err("VFS (%s): error: device does not support dax\n",
				sb->s_id);
		return -EOPNOTSUPP;
	}

	id = dax_read_lock();
	len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
	dax_read_unlock(id);

	put_dax(dax_dev);

	if (len < 1) {
		pr_err("VFS (%s): error: dax access failed (%ld)",
				sb->s_id, len);
		return len < 0 ? len : -EIO;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(__bdev_dax_supported);
#endif

/**
 * 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;
	struct inode *inode;

	dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL);
	inode = &dax_dev->inode;
	inode->i_rdev = 0;
	return 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;
	if (inode->i_rdev)
		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, MINORMASK+1, 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;

	memset(dax_dev, 0, sizeof(*dax_dev));
	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;

	rc = alloc_chrdev_region(&dax_devt, 0, MINORMASK+1, "dax");
	if (rc)
		__dax_fs_exit();
	return rc;
}

static void __exit dax_fs_exit(void)
{
	unregister_chrdev_region(dax_devt, MINORMASK+1);
	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>
ef510424	17	#include <linux/genhd.h>
7b6be844 DW	18	#include <linux/cdev.h>
	19	#include <linux/hash.h>
	20	#include <linux/slab.h>
6568b08b	21	#include <linux/dax.h>
7b6be844 DW	22	#include <linux/fs.h>
7b6be844 DW	23
7b6be844 DW	24	static dev_t dax_devt;
	25	DEFINE_STATIC_SRCU(dax_srcu);
	26	static struct vfsmount *dax_mnt;
	27	static DEFINE_IDA(dax_minor_ida);
	28	static struct kmem_cache *dax_cache __read_mostly;
	29	static struct super_block *dax_superblock __read_mostly;
	30
72058005 DW	31	#define DAX_HASH_SIZE (PAGE_SIZE / sizeof(struct hlist_head))
	32	static struct hlist_head dax_host_list[DAX_HASH_SIZE];
	33	static DEFINE_SPINLOCK(dax_host_lock);
	34
7b6be844 DW	35	int dax_read_lock(void)
	36	{
	37	return srcu_read_lock(&dax_srcu);
	38	}
	39	EXPORT_SYMBOL_GPL(dax_read_lock);
	40
	41	void dax_read_unlock(int id)
	42	{
	43	srcu_read_unlock(&dax_srcu, id);
	44	}
	45	EXPORT_SYMBOL_GPL(dax_read_unlock);
	46
9d109081	47	#ifdef CONFIG_BLOCK
ef510424 DW	48	int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
	49	pgoff_t *pgoff)
	50	{
	51	phys_addr_t phys_off = (get_start_sect(bdev) + sector) * 512;
	52
	53	if (pgoff)
	54	*pgoff = PHYS_PFN(phys_off);
	55	if (phys_off % PAGE_SIZE \|\| size % PAGE_SIZE)
	56	return -EINVAL;
	57	return 0;
	58	}
	59	EXPORT_SYMBOL(bdev_dax_pgoff);
	60
	61	/**
	62	* __bdev_dax_supported() - Check if the device supports dax for filesystem
	63	* @sb: The superblock of the device
	64	* @blocksize: The block size of the device
	65	*
	66	* This is a library function for filesystems to check if the block device
	67	* can be mounted with dax option.
	68	*
	69	* Return: negative errno if unsupported, 0 if supported.
	70	*/
	71	int __bdev_dax_supported(struct super_block *sb, int blocksize)
	72	{
	73	struct block_device *bdev = sb->s_bdev;
	74	struct dax_device *dax_dev;
	75	pgoff_t pgoff;
	76	int err, id;
	77	void *kaddr;
	78	pfn_t pfn;
	79	long len;
	80
	81	if (blocksize != PAGE_SIZE) {
	82	pr_err("VFS (%s): error: unsupported blocksize for dax\n",
	83	sb->s_id);
	84	return -EINVAL;
	85	}
	86
	87	err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
	88	if (err) {
	89	pr_err("VFS (%s): error: unaligned partition for dax\n",
	90	sb->s_id);
	91	return err;
	92	}
	93
	94	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
	95	if (!dax_dev) {
	96	pr_err("VFS (%s): error: device does not support dax\n",
	97	sb->s_id);
	98	return -EOPNOTSUPP;
	99	}
	100
	101	id = dax_read_lock();
	102	len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
	103	dax_read_unlock(id);
	104
	105	put_dax(dax_dev);
	106
	107	if (len < 1) {
	108	pr_err("VFS (%s): error: dax access failed (%ld)",
	109	sb->s_id, len);
	110	return len < 0 ? len : -EIO;
	111	}
112
113	return 0;
114	}
115	EXPORT_SYMBOL_GPL(__bdev_dax_supported);
9d109081	116	#endif
ef510424	117
7b6be844 DW	118	/**
	119	* struct dax_device - anchor object for dax services
	120	* @inode: core vfs
	121	* @cdev: optional character interface for "device dax"
72058005	122	* @host: optional name for lookups where the device path is not available
7b6be844 DW	123	* @private: dax driver private data
	124	* @alive: !alive + rcu grace period == no new operations / mappings
	125	*/
	126	struct dax_device {
72058005	127	struct hlist_node list;
7b6be844 DW	128	struct inode inode;
7b6be844 DW	129	struct cdev cdev;
72058005	130	const char *host;
7b6be844 DW	131	void *private;
7b6be844 DW	132	bool alive;
6568b08b	133	const struct dax_operations *ops;
7b6be844 DW	134	};
7b6be844 DW	135
b0686260 DW	136	/**
	137	* dax_direct_access() - translate a device pgoff to an absolute pfn
	138	* @dax_dev: a dax_device instance representing the logical memory range
	139	* @pgoff: offset in pages from the start of the device to translate
	140	* @nr_pages: number of consecutive pages caller can handle relative to @pfn
	141	* @kaddr: output parameter that returns a virtual address mapping of pfn
	142	* @pfn: output parameter that returns an absolute pfn translation of @pgoff
	143	*
	144	* Return: negative errno if an error occurs, otherwise the number of
	145	* pages accessible at the device relative @pgoff.
	146	*/
	147	long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
	148	void *kaddr, pfn_t pfn)
	149	{
	150	long avail;
	151
	152	/*
	153	* The device driver is allowed to sleep, in order to make the
	154	* memory directly accessible.
	155	*/
	156	might_sleep();
	157
	158	if (!dax_dev)
	159	return -EOPNOTSUPP;
	160
	161	if (!dax_alive(dax_dev))
	162	return -ENXIO;
	163
	164	if (nr_pages < 0)
	165	return nr_pages;
	166
	167	avail = dax_dev->ops->direct_access(dax_dev, pgoff, nr_pages,
	168	kaddr, pfn);
	169	if (!avail)
	170	return -ERANGE;
	171	return min(avail, nr_pages);
	172	}
	173	EXPORT_SYMBOL_GPL(dax_direct_access);
	174
7b6be844 DW	175	bool dax_alive(struct dax_device *dax_dev)
	176	{
	177	lockdep_assert_held(&dax_srcu);
	178	return dax_dev->alive;
	179	}
	180	EXPORT_SYMBOL_GPL(dax_alive);
	181
72058005 DW	182	static int dax_host_hash(const char *host)
	183	{
	184	return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE;
	185	}
	186
7b6be844 DW	187	/*
	188	* Note, rcu is not protecting the liveness of dax_dev, rcu is ensuring
	189	* that any fault handlers or operations that might have seen
	190	* dax_alive(), have completed. Any operations that start after
	191	* synchronize_srcu() has run will abort upon seeing !dax_alive().
	192	*/
	193	void kill_dax(struct dax_device *dax_dev)
	194	{
	195	if (!dax_dev)
	196	return;
	197
	198	dax_dev->alive = false;
72058005	199
7b6be844	200	synchronize_srcu(&dax_srcu);
72058005 DW	201
	202	spin_lock(&dax_host_lock);
	203	hlist_del_init(&dax_dev->list);
	204	spin_unlock(&dax_host_lock);
	205
7b6be844 DW	206	dax_dev->private = NULL;
	207	}
	208	EXPORT_SYMBOL_GPL(kill_dax);
	209
	210	static struct inode dax_alloc_inode(struct super_block sb)
	211	{
	212	struct dax_device *dax_dev;
b9d39d17	213	struct inode *inode;
7b6be844 DW	214
7b6be844 DW	215	dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL);
b9d39d17 DW	216	inode = &dax_dev->inode;
	217	inode->i_rdev = 0;
	218	return inode;
7b6be844 DW	219	}
	220
	221	static struct dax_device to_dax_dev(struct inode inode)
	222	{
	223	return container_of(inode, struct dax_device, inode);
	224	}
	225
	226	static void dax_i_callback(struct rcu_head *head)
	227	{
	228	struct inode *inode = container_of(head, struct inode, i_rcu);
	229	struct dax_device *dax_dev = to_dax_dev(inode);
	230
72058005 DW	231	kfree(dax_dev->host);
72058005 DW	232	dax_dev->host = NULL;
b9d39d17 DW	233	if (inode->i_rdev)
b9d39d17 DW	234	ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev));
7b6be844 DW	235	kmem_cache_free(dax_cache, dax_dev);
	236	}
	237
	238	static void dax_destroy_inode(struct inode *inode)
	239	{
	240	struct dax_device *dax_dev = to_dax_dev(inode);
	241
	242	WARN_ONCE(dax_dev->alive,
	243	"kill_dax() must be called before final iput()\n");
	244	call_rcu(&inode->i_rcu, dax_i_callback);
	245	}
	246
	247	static const struct super_operations dax_sops = {
	248	.statfs = simple_statfs,
	249	.alloc_inode = dax_alloc_inode,
	250	.destroy_inode = dax_destroy_inode,
	251	.drop_inode = generic_delete_inode,
	252	};
	253
	254	static struct dentry dax_mount(struct file_system_type fs_type,
	255	int flags, const char dev_name, void data)
	256	{
	257	return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC);
	258	}
	259
	260	static struct file_system_type dax_fs_type = {
	261	.name = "dax",
	262	.mount = dax_mount,
	263	.kill_sb = kill_anon_super,
	264	};
	265
	266	static int dax_test(struct inode inode, void data)
	267	{
	268	dev_t devt = (dev_t ) data;
	269
	270	return inode->i_rdev == devt;
	271	}
	272
	273	static int dax_set(struct inode inode, void data)
	274	{
	275	dev_t devt = (dev_t ) data;
	276
	277	inode->i_rdev = devt;
	278	return 0;
	279	}
	280
	281	static struct dax_device *dax_dev_get(dev_t devt)
	282	{
	283	struct dax_device *dax_dev;
	284	struct inode *inode;
	285
	286	inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
	287	dax_test, dax_set, &devt);
	288
	289	if (!inode)
	290	return NULL;
	291
	292	dax_dev = to_dax_dev(inode);
	293	if (inode->i_state & I_NEW) {
	294	dax_dev->alive = true;
	295	inode->i_cdev = &dax_dev->cdev;
	296	inode->i_mode = S_IFCHR;
	297	inode->i_flags = S_DAX;
	298	mapping_set_gfp_mask(&inode->i_data, GFP_USER);
299	unlock_new_inode(inode);
300	}
301
302	return dax_dev;
303	}
304
72058005 DW	305	static void dax_add_host(struct dax_device dax_dev, const char host)
	306	{
	307	int hash;
	308
	309	/*
	310	* Unconditionally init dax_dev since it's coming from a
	311	* non-zeroed slab cache
	312	*/
	313	INIT_HLIST_NODE(&dax_dev->list);
	314	dax_dev->host = host;
	315	if (!host)
	316	return;
	317
	318	hash = dax_host_hash(host);
	319	spin_lock(&dax_host_lock);
	320	hlist_add_head(&dax_dev->list, &dax_host_list[hash]);
	321	spin_unlock(&dax_host_lock);
	322	}
	323
6568b08b DW	324	struct dax_device alloc_dax(void private, const char *__host,
6568b08b DW	325	const struct dax_operations *ops)
7b6be844 DW	326	{
7b6be844 DW	327	struct dax_device *dax_dev;
72058005	328	const char *host;
7b6be844 DW	329	dev_t devt;
	330	int minor;
	331
72058005 DW	332	host = kstrdup(__host, GFP_KERNEL);
	333	if (__host && !host)
	334	return NULL;
	335
cf1e2289	336	minor = ida_simple_get(&dax_minor_ida, 0, MINORMASK+1, GFP_KERNEL);
7b6be844	337	if (minor < 0)
72058005	338	goto err_minor;
7b6be844 DW	339
	340	devt = MKDEV(MAJOR(dax_devt), minor);
	341	dax_dev = dax_dev_get(devt);
	342	if (!dax_dev)
72058005	343	goto err_dev;
7b6be844	344
72058005	345	dax_add_host(dax_dev, host);
6568b08b	346	dax_dev->ops = ops;
7b6be844 DW	347	dax_dev->private = private;
	348	return dax_dev;
	349
72058005	350	err_dev:
7b6be844	351	ida_simple_remove(&dax_minor_ida, minor);
72058005 DW	352	err_minor:
72058005 DW	353	kfree(host);
7b6be844 DW	354	return NULL;
	355	}
	356	EXPORT_SYMBOL_GPL(alloc_dax);
	357
	358	void put_dax(struct dax_device *dax_dev)
	359	{
	360	if (!dax_dev)
	361	return;
	362	iput(&dax_dev->inode);
	363	}
	364	EXPORT_SYMBOL_GPL(put_dax);
	365
72058005 DW	366	/**
	367	* dax_get_by_host() - temporary lookup mechanism for filesystem-dax
	368	* @host: alternate name for the device registered by a dax driver
	369	*/
	370	struct dax_device dax_get_by_host(const char host)
	371	{
	372	struct dax_device dax_dev, found = NULL;
	373	int hash, id;
	374
	375	if (!host)
	376	return NULL;
	377
	378	hash = dax_host_hash(host);
	379
	380	id = dax_read_lock();
	381	spin_lock(&dax_host_lock);
	382	hlist_for_each_entry(dax_dev, &dax_host_list[hash], list) {
	383	if (!dax_alive(dax_dev)
	384	\|\| strcmp(host, dax_dev->host) != 0)
	385	continue;
	386
	387	if (igrab(&dax_dev->inode))
	388	found = dax_dev;
	389	break;
	390	}
	391	spin_unlock(&dax_host_lock);
	392	dax_read_unlock(id);
	393
	394	return found;
	395	}
	396	EXPORT_SYMBOL_GPL(dax_get_by_host);
	397
7b6be844 DW	398	/**
	399	* inode_dax: convert a public inode into its dax_dev
	400	* @inode: An inode with i_cdev pointing to a dax_dev
	401	*
	402	* Note this is not equivalent to to_dax_dev() which is for private
	403	* internal use where we know the inode filesystem type == dax_fs_type.
	404	*/
	405	struct dax_device inode_dax(struct inode inode)
	406	{
	407	struct cdev *cdev = inode->i_cdev;
	408
	409	return container_of(cdev, struct dax_device, cdev);
	410	}
	411	EXPORT_SYMBOL_GPL(inode_dax);
	412
	413	struct inode dax_inode(struct dax_device dax_dev)
	414	{
	415	return &dax_dev->inode;
	416	}
	417	EXPORT_SYMBOL_GPL(dax_inode);
	418
	419	void dax_get_private(struct dax_device dax_dev)
	420	{
	421	return dax_dev->private;
	422	}
	423	EXPORT_SYMBOL_GPL(dax_get_private);
	424
	425	static void init_once(void *_dax_dev)
	426	{
	427	struct dax_device *dax_dev = _dax_dev;
	428	struct inode *inode = &dax_dev->inode;
	429
b9d39d17	430	memset(dax_dev, 0, sizeof(*dax_dev));
7b6be844 DW	431	inode_init_once(inode);
	432	}
	433
	434	static int __dax_fs_init(void)
	435	{
	436	int rc;
	437
	438	dax_cache = kmem_cache_create("dax_cache", sizeof(struct dax_device), 0,
	439	(SLAB_HWCACHE_ALIGN\|SLAB_RECLAIM_ACCOUNT\|
	440	SLAB_MEM_SPREAD\|SLAB_ACCOUNT),
	441	init_once);
	442	if (!dax_cache)
	443	return -ENOMEM;
	444
	445	rc = register_filesystem(&dax_fs_type);
	446	if (rc)
	447	goto err_register_fs;
	448
	449	dax_mnt = kern_mount(&dax_fs_type);
	450	if (IS_ERR(dax_mnt)) {
	451	rc = PTR_ERR(dax_mnt);
	452	goto err_mount;
	453	}
	454	dax_superblock = dax_mnt->mnt_sb;
	455
	456	return 0;
	457
	458	err_mount:
	459	unregister_filesystem(&dax_fs_type);
	460	err_register_fs:
	461	kmem_cache_destroy(dax_cache);
	462
	463	return rc;
	464	}
	465
	466	static void __dax_fs_exit(void)
	467	{
	468	kern_unmount(dax_mnt);
	469	unregister_filesystem(&dax_fs_type);
	470	kmem_cache_destroy(dax_cache);
	471	}
	472
	473	static int __init dax_fs_init(void)
	474	{
	475	int rc;
	476
	477	rc = __dax_fs_init();
	478	if (rc)
	479	return rc;
	480
cf1e2289	481	rc = alloc_chrdev_region(&dax_devt, 0, MINORMASK+1, "dax");
7b6be844 DW	482	if (rc)
	483	__dax_fs_exit();
	484	return rc;
	485	}
	486
	487	static void __exit dax_fs_exit(void)
	488	{
cf1e2289	489	unregister_chrdev_region(dax_devt, MINORMASK+1);
7b6be844 DW	490	ida_destroy(&dax_minor_ida);
	491	__dax_fs_exit();
	492	}
	493
	494	MODULE_AUTHOR("Intel Corporation");
	495	MODULE_LICENSE("GPL v2");
	496	subsys_initcall(dax_fs_init);
	497	module_exit(dax_fs_exit);