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Commit 3bc52c45 authored by Dan Williams's avatar Dan Williams
Browse files

dax: define a unified inode/address_space for device-dax mappings 



In support of enabling resize / truncate of device-dax instances, define
a pseudo-fs to provide a unified inode/address space for vm operations.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent ba09c01d

drivers/dax/dax.c

+146 −4
Original line number Original line Diff line number Diff line
@@ -13,7 +13,9 @@ 
#include <linux/pagemap.h>

#include <linux/pagemap.h>

#include <linux/module.h>

#include <linux/module.h>

#include <linux/device.h>

#include <linux/device.h>

#include <linux/mount.h>

#include <linux/pfn_t.h>

#include <linux/pfn_t.h>

#include <linux/hash.h>

#include <linux/cdev.h>

#include <linux/cdev.h>

#include <linux/slab.h>

#include <linux/slab.h>

#include <linux/dax.h>

#include <linux/dax.h>
@@ -26,6 +28,9 @@ static struct class *dax_class; 
static DEFINE_IDA(dax_minor_ida);

static DEFINE_IDA(dax_minor_ida);

static int nr_dax = CONFIG_NR_DEV_DAX;

static int nr_dax = CONFIG_NR_DEV_DAX;

module_param(nr_dax, int, S_IRUGO);

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");

MODULE_PARM_DESC(nr_dax, "max number of device-dax instances");





/**

/**
@@ -61,6 +66,7 @@ struct dax_region { 
 */

 */

struct dax_dev {

struct dax_dev {

	struct dax_region *region;

	struct dax_region *region;

	struct inode *inode;

	struct device dev;

	struct device dev;

	struct cdev cdev;

	struct cdev cdev;

	bool alive;

	bool alive;
@@ -69,6 +75,117 @@ struct dax_dev { 
	struct resource res[0];

	struct resource res[0];

};

};





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)

static void dax_region_free(struct kref *kref)

{

{

	struct dax_region *dax_region;

	struct dax_region *dax_region;
@@ -379,6 +496,9 @@ static int dax_open(struct inode *inode, struct file *filp) 




	dax_dev = container_of(inode->i_cdev, struct dax_dev, cdev);

	dax_dev = container_of(inode->i_cdev, struct dax_dev, cdev);

	dev_dbg(&dax_dev->dev, "%s\n", __func__);

	dev_dbg(&dax_dev->dev, "%s\n", __func__);

	inode->i_mapping = dax_dev->inode->i_mapping;

	inode->i_mapping->host = dax_dev->inode;

	filp->f_mapping = inode->i_mapping;

	filp->private_data = dax_dev;

	filp->private_data = dax_dev;

	inode->i_flags = S_DAX;

	inode->i_flags = S_DAX;
@@ -410,6 +530,7 @@ static void dax_dev_release(struct device *dev) 
	ida_simple_remove(&dax_region->ida, dax_dev->id);

	ida_simple_remove(&dax_region->ida, dax_dev->id);

	ida_simple_remove(&dax_minor_ida, MINOR(dev->devt));

	ida_simple_remove(&dax_minor_ida, MINOR(dev->devt));

	dax_region_put(dax_region);

	dax_region_put(dax_region);

	iput(dax_dev->inode);

	kfree(dax_dev);

	kfree(dax_dev);

}

}
@@ -459,6 +580,12 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res, 
		goto err_minor;

		goto err_minor;

	}

	}





	dax_dev->inode = dax_inode_get(&dax_dev->cdev, dev_t);

	if (!dax_dev->inode) {

		rc = -ENOMEM;

		goto err_inode;

	}



	/* device_initialize() so cdev can reference kobj parent */

	/* device_initialize() so cdev can reference kobj parent */

	dev_t = MKDEV(MAJOR(dax_devt), minor);

	dev_t = MKDEV(MAJOR(dax_devt), minor);

	dev = &dax_dev->dev;

	dev = &dax_dev->dev;
@@ -494,6 +621,8 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res, 
	return devm_add_action_or_reset(dax_region->dev, unregister_dax_dev, dev);

	return devm_add_action_or_reset(dax_region->dev, unregister_dax_dev, dev);





 err_cdev:

 err_cdev:

	iput(dax_dev->inode);

 err_inode:

	ida_simple_remove(&dax_minor_ida, minor);

	ida_simple_remove(&dax_minor_ida, minor);

 err_minor:

 err_minor:

	ida_simple_remove(&dax_region->ida, dax_dev->id);

	ida_simple_remove(&dax_region->ida, dax_dev->id);
@@ -508,16 +637,28 @@ static int __init dax_init(void) 
{

{

	int rc;

	int rc;





	rc = dax_inode_init();

	if (rc)

		return rc;



	nr_dax = max(nr_dax, 256);

	nr_dax = max(nr_dax, 256);

	rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax");

	rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax");

	if (rc)

	if (rc)

		return rc;

		goto err_chrdev;





	dax_class = class_create(THIS_MODULE, "dax");

	dax_class = class_create(THIS_MODULE, "dax");

	if (IS_ERR(dax_class))

	if (IS_ERR(dax_class)) {

		unregister_chrdev_region(dax_devt, nr_dax);

		rc = PTR_ERR(dax_class);

		goto err_class;

	}





	return PTR_ERR_OR_ZERO(dax_class);

	return 0;



 err_class:

	unregister_chrdev_region(dax_devt, nr_dax);

 err_chrdev:

	dax_inode_exit();

	return rc;

}

}





static void __exit dax_exit(void)

static void __exit dax_exit(void)
@@ -525,6 +666,7 @@ static void __exit dax_exit(void) 
	class_destroy(dax_class);

	class_destroy(dax_class);

	unregister_chrdev_region(dax_devt, nr_dax);

	unregister_chrdev_region(dax_devt, nr_dax);

	ida_destroy(&dax_minor_ida);

	ida_destroy(&dax_minor_ida);

	dax_inode_exit();

}

}





MODULE_AUTHOR("Intel Corporation");

MODULE_AUTHOR("Intel Corporation");

fs/char_dev.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -406,6 +406,7 @@ void cd_forget(struct inode *inode) 
	spin_lock(&cdev_lock);

	spin_lock(&cdev_lock);

	list_del_init(&inode->i_devices);

	list_del_init(&inode->i_devices);

	inode->i_cdev = NULL;

	inode->i_cdev = NULL;

	inode->i_mapping = &inode->i_data;

	spin_unlock(&cdev_lock);

	spin_unlock(&cdev_lock);

}

}

include/uapi/linux/magic.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -65,6 +65,7 @@ 
#define V9FS_MAGIC		0x01021997

#define V9FS_MAGIC		0x01021997





#define BDEVFS_MAGIC            0x62646576

#define BDEVFS_MAGIC            0x62646576

#define DAXFS_MAGIC             0x64646178

#define BINFMTFS_MAGIC          0x42494e4d

#define BINFMTFS_MAGIC          0x42494e4d

#define DEVPTS_SUPER_MAGIC	0x1cd1

#define DEVPTS_SUPER_MAGIC	0x1cd1

#define FUTEXFS_SUPER_MAGIC	0xBAD1DEA

#define FUTEXFS_SUPER_MAGIC	0xBAD1DEA