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dax: convert to the cdev api

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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: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2016-07-24 15:55:42 -07:00
parent ebd84d724c
commit ba09c01d2f
2 changed files with 46 additions and 41 deletions
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5
drivers/dax/Kconfig
View file

@ -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

82
drivers/dax/dax.c
View file

@ -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;
struct dax_dev *dax_dev;
dev = dax_dev_find(inode->i_rdev);
if (!dev)
return -ENXIO;
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);
}