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dax: introduce dax_operations

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Track a set of dax_operations per dax_device that can be set at
alloc_dax() time. These operations will be used to stop the abuse of
block_device_operations for communicating dax capabilities to
filesystems. It will also be used to replace the "pmem api" and move
pmem-specific cache maintenance, and other dax-driver-specific
filesystem-dax operations, to dax device methods. In particular this
allows us to stop abusing __copy_user_nocache(), via memcpy_to_pmem(),
with a driver specific replacement.

This is a standalone introduction of the operations. Follow on patches
convert each dax-driver and teach fs/dax.c to use ->direct_access() from
dax_operations instead of block_device_operations.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2017-01-24 18:44:18 -08:00
parent 7205800541
commit 6568b08b77
4 changed files with 23 additions and 3 deletions
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4
drivers/dax/dax.h
View file

@ -13,7 +13,9 @@
#ifndef __DAX_H__
#define __DAX_H__
struct dax_device;
struct dax_device *alloc_dax(void *private, const char *host);
struct dax_operations;
struct dax_device *alloc_dax(void *private, const char *host,
const struct dax_operations *ops);
void put_dax(struct dax_device *dax_dev);
bool dax_alive(struct dax_device *dax_dev);
void kill_dax(struct dax_device *dax_dev);

6
drivers/dax/device.c
View file

@ -645,7 +645,11 @@ struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
goto err_id;
}
dax_dev = alloc_dax(dev_dax, NULL);
/*
* No 'host' or dax_operations since there is no access to this
* device outside of mmap of the resulting character device.
*/
dax_dev = alloc_dax(dev_dax, NULL, NULL);
if (!dax_dev)
goto err_dax;

6
drivers/dax/super.c
View file

@ -17,6 +17,7 @@
#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;
@ -61,6 +62,7 @@ struct dax_device {
const char *host;
void *private;
bool alive;
const struct dax_operations *ops;
};
bool dax_alive(struct dax_device *dax_dev)
@ -208,7 +210,8 @@ static void dax_add_host(struct dax_device *dax_dev, const char *host)
spin_unlock(&dax_host_lock);
}
struct dax_device *alloc_dax(void *private, const char *__host)
struct dax_device *alloc_dax(void *private, const char *__host,
const struct dax_operations *ops)
{
struct dax_device *dax_dev;
const char *host;
@ -229,6 +232,7 @@ struct dax_device *alloc_dax(void *private, const char *__host)
goto err_dev;
dax_add_host(dax_dev, host);
dax_dev->ops = ops;
dax_dev->private = private;
return dax_dev;

10
include/linux/dax.h
View file

@ -7,6 +7,16 @@
#include <asm/pgtable.h>
struct iomap_ops;
struct dax_device;
struct dax_operations {
/*
* direct_access: translate a device-relative
* logical-page-offset into an absolute physical pfn. Return the
* number of pages available for DAX at that pfn.
*/
long (*direct_access)(struct dax_device *, pgoff_t, long,
void **, pfn_t *);
};
int dax_read_lock(void);
void dax_read_unlock(int id);