Commit ba09c01d authored by Dan Williams's avatar Dan Williams
Browse files

dax: convert to the cdev api 



A goal of the device-DAX interface is to be able to support many
exclusive allocations (partitions) of performance / feature
differentiated memory.  This count may exceed the default minors limit
of 256.

As a result of switching to an embedded cdev the inode-to-dax_dev
conversion is simplified, as well as reference counting which can switch
to the cdev kobject lifetime.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent ebd84d72

drivers/dax/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -23,4 +23,9 @@ config DEV_DAX_PMEM 


	  Say Y if unsure



config NR_DEV_DAX

	int "Maximum number of Device-DAX instances"

	default 32768

	range 256 2147483647



endif

drivers/dax/dax.c

+41 −41
Original line number Diff line number Diff line
@@ -14,15 +14,19 @@ 
#include <linux/module.h>

#include <linux/device.h>

#include <linux/pfn_t.h>

#include <linux/cdev.h>

#include <linux/slab.h>

#include <linux/dax.h>

#include <linux/fs.h>

#include <linux/mm.h>

#include "dax.h"



static int dax_major;

static dev_t dax_devt;

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);

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



/**

 * struct dax_region - mapping infrastructure for dax devices
@@ -49,6 +53,7 @@ struct dax_region { 
 * struct dax_dev - subdivision of a dax region

 * @region - parent region

 * @dev - device backing the character device

 * @cdev - core chardev data

 * @alive - !alive + rcu grace period == no new mappings can be established

 * @id - child id in the region

 * @num_resources - number of physical address extents in this device
@@ -57,6 +62,7 @@ struct dax_region { 
struct dax_dev {

	struct dax_region *region;

	struct device dev;

	struct cdev cdev;

	bool alive;

	int id;

	int num_resources;
@@ -367,29 +373,12 @@ static unsigned long dax_get_unmapped_area(struct file *filp, 
	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);

}



static int __match_devt(struct device *dev, const void *data)

{

	const dev_t *devt = data;



	return dev->devt == *devt;

}



static struct device *dax_dev_find(dev_t dev_t)

{

	return class_find_device(dax_class, NULL, &dev_t, __match_devt);

}



static int dax_open(struct inode *inode, struct file *filp)

{

	struct dax_dev *dax_dev = NULL;

	struct device *dev;



	dev = dax_dev_find(inode->i_rdev);

	if (!dev)

		return -ENXIO;

	struct dax_dev *dax_dev;



	dax_dev = to_dax_dev(dev);

	dev_dbg(dev, "%s\n", __func__);

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

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

	filp->private_data = dax_dev;

	inode->i_flags = S_DAX;
@@ -399,11 +388,8 @@ 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 device *dev = &dax_dev->dev;



	dev_dbg(dev, "%s\n", __func__);

	put_device(dev);



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

	return 0;

}
@@ -430,6 +416,7 @@ static void dax_dev_release(struct device *dev) 
static void unregister_dax_dev(void *dev)

{

	struct dax_dev *dax_dev = to_dax_dev(dev);

	struct cdev *cdev = &dax_dev->cdev;



	dev_dbg(dev, "%s\n", __func__);
@@ -442,6 +429,7 @@ static void unregister_dax_dev(void *dev) 
	 */

	dax_dev->alive = false;

	synchronize_rcu();

	cdev_del(cdev);

	device_unregister(dev);

}
@@ -451,17 +439,13 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res, 
	struct device *parent = dax_region->dev;

	struct dax_dev *dax_dev;

	struct device *dev;

	struct cdev *cdev;

	int rc, minor;

	dev_t dev_t;



	dax_dev = kzalloc(sizeof(*dax_dev) + sizeof(*res) * count, GFP_KERNEL);

	if (!dax_dev)

		return -ENOMEM;

	memcpy(dax_dev->res, res, sizeof(*res) * count);

	dax_dev->num_resources = count;

	dax_dev->alive = true;

	dax_dev->region = dax_region;

	kref_get(&dax_region->kref);



	dax_dev->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);

	if (dax_dev->id < 0) {
@@ -475,10 +459,26 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res, 
		goto err_minor;

	}



	dev_t = MKDEV(dax_major, minor);



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

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

	dev = &dax_dev->dev;

	device_initialize(dev);



	cdev = &dax_dev->cdev;

	cdev_init(cdev, &dax_fops);

	cdev->owner = parent->driver->owner;

	cdev->kobj.parent = &dev->kobj;

	rc = cdev_add(&dax_dev->cdev, dev_t, 1);

	if (rc)

		goto err_cdev;



	/* from here on we're committed to teardown via dax_dev_release() */

	memcpy(dax_dev->res, res, sizeof(*res) * count);

	dax_dev->num_resources = count;

	dax_dev->alive = true;

	dax_dev->region = dax_region;

	kref_get(&dax_region->kref);



	dev->devt = dev_t;

	dev->class = dax_class;

	dev->parent = parent;
@@ -493,6 +493,8 @@ 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);



 err_cdev:

	ida_simple_remove(&dax_minor_ida, minor);

 err_minor:

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

 err_id:
@@ -506,24 +508,22 @@ static int __init dax_init(void) 
{

	int rc;



	rc = register_chrdev(0, "dax", &dax_fops);

	if (rc < 0)

	nr_dax = max(nr_dax, 256);

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

	if (rc)

		return rc;

	dax_major = rc;



	dax_class = class_create(THIS_MODULE, "dax");

	if (IS_ERR(dax_class)) {

		unregister_chrdev(dax_major, "dax");

		return PTR_ERR(dax_class);

	}

	if (IS_ERR(dax_class))

		unregister_chrdev_region(dax_devt, nr_dax);



	return 0;

	return PTR_ERR_OR_ZERO(dax_class);

}



static void __exit dax_exit(void)

{

	class_destroy(dax_class);

	unregister_chrdev(dax_major, "dax");

	unregister_chrdev_region(dax_devt, nr_dax);

	ida_destroy(&dax_minor_ida);

}

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