device-dax: Add /sys/class/dax backwards compatibility

On the expectation that some environments may not upgrade libdaxctl
(userspace component that depends on the /sys/class/dax hierarchy),
provide a default / legacy dax_pmem_compat driver. The dax_pmem_compat
driver implements the original /sys/class/dax sysfs layout rather than
/sys/bus/dax. When userspace is upgraded it can blacklist this module
and switch to the dax_pmem driver going forward.

CONFIG_DEV_DAX_PMEM_COMPAT and supporting code will be deleted according
to the dax_pmem entry in Documentation/ABI/obsolete/.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2017-07-16 13:51:53 -07:00
parent d200781ef2
commit 730926c3b0
11 changed files with 229 additions and 50 deletions

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@ -0,0 +1,22 @@
What: /sys/class/dax/
Date: May, 2016
KernelVersion: v4.7
Contact: linux-nvdimm@lists.01.org
Description: Device DAX is the device-centric analogue of Filesystem
DAX (CONFIG_FS_DAX). It allows memory ranges to be
allocated and mapped without need of an intervening file
system. Device DAX is strict, precise and predictable.
Specifically this interface:
1/ Guarantees fault granularity with respect to a given
page size (pte, pmd, or pud) set at configuration time.
2/ Enforces deterministic behavior by being strict about
what fault scenarios are supported.
The /sys/class/dax/ interface enumerates all the
device-dax instances in the system. The ABI is
deprecated and will be removed after 2020. It is
replaced with the DAX bus interface /sys/bus/dax/ where
device-dax instances can be found under
/sys/bus/dax/devices/

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@ -23,12 +23,22 @@ config DEV_DAX
config DEV_DAX_PMEM
tristate "PMEM DAX: direct access to persistent memory"
depends on LIBNVDIMM && NVDIMM_DAX && DEV_DAX
depends on m # until we can kill DEV_DAX_PMEM_COMPAT
default DEV_DAX
help
Support raw access to persistent memory. Note that this
driver consumes memory ranges allocated and exported by the
libnvdimm sub-system.
Say Y if unsure
Say M if unsure
config DEV_DAX_PMEM_COMPAT
tristate "PMEM DAX: support the deprecated /sys/class/dax interface"
depends on DEV_DAX_PMEM
default DEV_DAX_PMEM
help
Older versions of the libdaxctl library expect to find all
device-dax instances under /sys/class/dax. If libdaxctl in
your distribution is older than v58 say M, otherwise say N.
endif

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@ -1,9 +1,9 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_DAX) += dax.o
obj-$(CONFIG_DEV_DAX) += device_dax.o
obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem.o
dax-y := super.o
dax-y += bus.o
dax_pmem-y := pmem.o
device_dax-y := device.o
obj-y += pmem/

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@ -9,6 +9,8 @@
#include "dax-private.h"
#include "bus.h"
static struct class *dax_class;
static DEFINE_MUTEX(dax_bus_lock);
#define DAX_NAME_LEN 30
@ -310,8 +312,8 @@ static void unregister_dev_dax(void *dev)
put_device(dev);
}
struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id,
struct dev_pagemap *pgmap)
struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
struct dev_pagemap *pgmap, enum dev_dax_subsys subsys)
{
struct device *parent = dax_region->dev;
struct dax_device *dax_dev;
@ -350,7 +352,10 @@ struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id,
inode = dax_inode(dax_dev);
dev->devt = inode->i_rdev;
dev->bus = &dax_bus_type;
if (subsys == DEV_DAX_BUS)
dev->bus = &dax_bus_type;
else
dev->class = dax_class;
dev->parent = parent;
dev->groups = dax_attribute_groups;
dev->release = dev_dax_release;
@ -374,7 +379,7 @@ struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id,
return ERR_PTR(rc);
}
EXPORT_SYMBOL_GPL(devm_create_dev_dax);
EXPORT_SYMBOL_GPL(__devm_create_dev_dax);
static int match_always_count;
@ -407,6 +412,7 @@ EXPORT_SYMBOL_GPL(__dax_driver_register);
void dax_driver_unregister(struct dax_device_driver *dax_drv)
{
struct device_driver *drv = &dax_drv->drv;
struct dax_id *dax_id, *_id;
mutex_lock(&dax_bus_lock);
@ -416,15 +422,28 @@ void dax_driver_unregister(struct dax_device_driver *dax_drv)
kfree(dax_id);
}
mutex_unlock(&dax_bus_lock);
driver_unregister(drv);
}
EXPORT_SYMBOL_GPL(dax_driver_unregister);
int __init dax_bus_init(void)
{
return bus_register(&dax_bus_type);
int rc;
if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
dax_class = class_create(THIS_MODULE, "dax");
if (IS_ERR(dax_class))
return PTR_ERR(dax_class);
}
rc = bus_register(&dax_bus_type);
if (rc)
class_destroy(dax_class);
return rc;
}
void __exit dax_bus_exit(void)
{
bus_unregister(&dax_bus_type);
class_destroy(dax_class);
}

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@ -2,7 +2,8 @@
/* Copyright(c) 2016 - 2018 Intel Corporation. All rights reserved. */
#ifndef __DAX_BUS_H__
#define __DAX_BUS_H__
struct device;
#include <linux/device.h>
struct dev_dax;
struct resource;
struct dax_device;
@ -10,8 +11,23 @@ struct dax_region;
void dax_region_put(struct dax_region *dax_region);
struct dax_region *alloc_dax_region(struct device *parent, int region_id,
struct resource *res, unsigned int align, unsigned long flags);
struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id,
struct dev_pagemap *pgmap);
enum dev_dax_subsys {
DEV_DAX_BUS,
DEV_DAX_CLASS,
};
struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
struct dev_pagemap *pgmap, enum dev_dax_subsys subsys);
static inline struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
int id, struct dev_pagemap *pgmap)
{
return __devm_create_dev_dax(dax_region, id, pgmap, DEV_DAX_BUS);
}
/* to be deleted when DEV_DAX_CLASS is removed */
struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys);
struct dax_device_driver {
struct device_driver drv;
@ -26,6 +42,10 @@ int __dax_driver_register(struct dax_device_driver *dax_drv,
void dax_driver_unregister(struct dax_device_driver *dax_drv);
void kill_dev_dax(struct dev_dax *dev_dax);
#if IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)
int dev_dax_probe(struct device *dev);
#endif
/*
* While run_dax() is potentially a generic operation that could be
* defined in include/linux/dax.h we don't want to grow any users

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@ -445,7 +445,7 @@ static void dev_dax_kill(void *dev_dax)
kill_dev_dax(dev_dax);
}
static int dev_dax_probe(struct device *dev)
int dev_dax_probe(struct device *dev)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
struct dax_device *dax_dev = dev_dax->dax_dev;
@ -484,7 +484,11 @@ static int dev_dax_probe(struct device *dev)
inode = dax_inode(dax_dev);
cdev = inode->i_cdev;
cdev_init(cdev, &dax_fops);
cdev->owner = dev->driver->owner;
if (dev->class) {
/* for the CONFIG_DEV_DAX_PMEM_COMPAT case */
cdev->owner = dev->parent->driver->owner;
} else
cdev->owner = dev->driver->owner;
cdev_set_parent(cdev, &dev->kobj);
rc = cdev_add(cdev, dev->devt, 1);
if (rc)
@ -497,6 +501,7 @@ static int dev_dax_probe(struct device *dev)
run_dax(dax_dev);
return devm_add_action_or_reset(dev, dev_dax_kill, dev_dax);
}
EXPORT_SYMBOL_GPL(dev_dax_probe);
static int dev_dax_remove(struct device *dev)
{

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@ -0,0 +1,7 @@
obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem.o
obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem_core.o
obj-$(CONFIG_DEV_DAX_PMEM_COMPAT) += dax_pmem_compat.o
dax_pmem-y := pmem.o
dax_pmem_core-y := core.o
dax_pmem_compat-y := compat.o

73
drivers/dax/pmem/compat.c Normal file
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@ -0,0 +1,73 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2016 - 2018 Intel Corporation. All rights reserved. */
#include <linux/percpu-refcount.h>
#include <linux/memremap.h>
#include <linux/module.h>
#include <linux/pfn_t.h>
#include <linux/nd.h>
#include "../bus.h"
/* we need the private definitions to implement compat suport */
#include "../dax-private.h"
static int dax_pmem_compat_probe(struct device *dev)
{
struct dev_dax *dev_dax = __dax_pmem_probe(dev, DEV_DAX_CLASS);
int rc;
if (IS_ERR(dev_dax))
return PTR_ERR(dev_dax);
if (!devres_open_group(&dev_dax->dev, dev_dax, GFP_KERNEL))
return -ENOMEM;
device_lock(&dev_dax->dev);
rc = dev_dax_probe(&dev_dax->dev);
device_unlock(&dev_dax->dev);
devres_close_group(&dev_dax->dev, dev_dax);
if (rc)
devres_release_group(&dev_dax->dev, dev_dax);
return rc;
}
static int dax_pmem_compat_release(struct device *dev, void *data)
{
device_lock(dev);
devres_release_group(dev, to_dev_dax(dev));
device_unlock(dev);
return 0;
}
static int dax_pmem_compat_remove(struct device *dev)
{
device_for_each_child(dev, NULL, dax_pmem_compat_release);
return 0;
}
static struct nd_device_driver dax_pmem_compat_driver = {
.probe = dax_pmem_compat_probe,
.remove = dax_pmem_compat_remove,
.drv = {
.name = "dax_pmem_compat",
},
.type = ND_DRIVER_DAX_PMEM,
};
static int __init dax_pmem_compat_init(void)
{
return nd_driver_register(&dax_pmem_compat_driver);
}
module_init(dax_pmem_compat_init);
static void __exit dax_pmem_compat_exit(void)
{
driver_unregister(&dax_pmem_compat_driver.drv);
}
module_exit(dax_pmem_compat_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Intel Corporation");
MODULE_ALIAS_ND_DEVICE(ND_DEVICE_DAX_PMEM);

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@ -1,24 +1,13 @@
/*
* Copyright(c) 2016 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/percpu-refcount.h>
// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2016 - 2018 Intel Corporation. All rights reserved. */
#include <linux/memremap.h>
#include <linux/module.h>
#include <linux/pfn_t.h>
#include "../nvdimm/pfn.h"
#include "../nvdimm/nd.h"
#include "bus.h"
#include "../../nvdimm/pfn.h"
#include "../../nvdimm/nd.h"
#include "../bus.h"
static int dax_pmem_probe(struct device *dev)
struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys)
{
struct resource res;
int rc, id, region_id;
@ -34,16 +23,16 @@ static int dax_pmem_probe(struct device *dev)
ndns = nvdimm_namespace_common_probe(dev);
if (IS_ERR(ndns))
return PTR_ERR(ndns);
return ERR_CAST(ndns);
nsio = to_nd_namespace_io(&ndns->dev);
/* parse the 'pfn' info block via ->rw_bytes */
rc = devm_nsio_enable(dev, nsio);
if (rc)
return rc;
return ERR_PTR(rc);
rc = nvdimm_setup_pfn(nd_pfn, &pgmap);
if (rc)
return rc;
return ERR_PTR(rc);
devm_nsio_disable(dev, nsio);
/* reserve the metadata area, device-dax will reserve the data */
@ -52,12 +41,12 @@ static int dax_pmem_probe(struct device *dev)
if (!devm_request_mem_region(dev, nsio->res.start, offset,
dev_name(&ndns->dev))) {
dev_warn(dev, "could not reserve metadata\n");
return -EBUSY;
return ERR_PTR(-EBUSY);
}
rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", &region_id, &id);
if (rc != 2)
return -EINVAL;
return ERR_PTR(-EINVAL);
/* adjust the dax_region resource to the start of data */
memcpy(&res, &pgmap.res, sizeof(res));
@ -65,26 +54,16 @@ static int dax_pmem_probe(struct device *dev)
dax_region = alloc_dax_region(dev, region_id, &res,
le32_to_cpu(pfn_sb->align), PFN_DEV|PFN_MAP);
if (!dax_region)
return -ENOMEM;
return ERR_PTR(-ENOMEM);
dev_dax = devm_create_dev_dax(dax_region, id, &pgmap);
dev_dax = __devm_create_dev_dax(dax_region, id, &pgmap, subsys);
/* child dev_dax instances now own the lifetime of the dax_region */
dax_region_put(dax_region);
return PTR_ERR_OR_ZERO(dev_dax);
return dev_dax;
}
static struct nd_device_driver dax_pmem_driver = {
.probe = dax_pmem_probe,
.drv = {
.name = "dax_pmem",
},
.type = ND_DRIVER_DAX_PMEM,
};
module_nd_driver(dax_pmem_driver);
EXPORT_SYMBOL_GPL(__dax_pmem_probe);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Intel Corporation");
MODULE_ALIAS_ND_DEVICE(ND_DEVICE_DAX_PMEM);

40
drivers/dax/pmem/pmem.c Normal file
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@ -0,0 +1,40 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2016 - 2018 Intel Corporation. All rights reserved. */
#include <linux/percpu-refcount.h>
#include <linux/memremap.h>
#include <linux/module.h>
#include <linux/pfn_t.h>
#include <linux/nd.h>
#include "../bus.h"
static int dax_pmem_probe(struct device *dev)
{
return PTR_ERR_OR_ZERO(__dax_pmem_probe(dev, DEV_DAX_BUS));
}
static struct nd_device_driver dax_pmem_driver = {
.probe = dax_pmem_probe,
.drv = {
.name = "dax_pmem",
},
.type = ND_DRIVER_DAX_PMEM,
};
static int __init dax_pmem_init(void)
{
return nd_driver_register(&dax_pmem_driver);
}
module_init(dax_pmem_init);
static void __exit dax_pmem_exit(void)
{
driver_unregister(&dax_pmem_driver.drv);
}
module_exit(dax_pmem_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Intel Corporation");
#if !IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)
/* For compat builds, don't load this module by default */
MODULE_ALIAS_ND_DEVICE(ND_DEVICE_DAX_PMEM);
#endif

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@ -35,6 +35,8 @@ obj-$(CONFIG_DAX) += dax.o
endif
obj-$(CONFIG_DEV_DAX) += device_dax.o
obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem.o
obj-$(CONFIG_DEV_DAX_PMEM) += dax_pmem_core.o
obj-$(CONFIG_DEV_DAX_PMEM_COMPAT) += dax_pmem_compat.o
nfit-y := $(ACPI_SRC)/core.o
nfit-y += $(ACPI_SRC)/intel.o
@ -65,7 +67,9 @@ device_dax-y += dax-dev.o
device_dax-y += device_dax_test.o
device_dax-y += config_check.o
dax_pmem-y := $(DAX_SRC)/pmem.o
dax_pmem-y := $(DAX_SRC)/pmem/pmem.o
dax_pmem_core-y := $(DAX_SRC)/pmem/core.o
dax_pmem_compat-y := $(DAX_SRC)/pmem/compat.o
dax_pmem-y += config_check.o
libnvdimm-y := $(NVDIMM_SRC)/core.o