device-dax: Add /sys/class/dax backwards compatibility
authorDan Williams <dan.j.williams@intel.com>
Sun, 16 Jul 2017 20:51:53 +0000 (13:51 -0700)
committerDan Williams <dan.j.williams@intel.com>
Mon, 7 Jan 2019 05:41:57 +0000 (21:41 -0800)
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>
Documentation/ABI/obsolete/sysfs-class-dax [new file with mode: 0644]
drivers/dax/Kconfig
drivers/dax/Makefile
drivers/dax/bus.c
drivers/dax/bus.h
drivers/dax/device.c
drivers/dax/pmem/Makefile [new file with mode: 0644]
drivers/dax/pmem/compat.c [new file with mode: 0644]
drivers/dax/pmem/core.c [moved from drivers/dax/pmem.c with 57% similarity]
drivers/dax/pmem/pmem.c [new file with mode: 0644]
tools/testing/nvdimm/Kbuild

diff --git a/Documentation/ABI/obsolete/sysfs-class-dax b/Documentation/ABI/obsolete/sysfs-class-dax
new file mode 100644 (file)
index 0000000..2cb9fc5
--- /dev/null
@@ -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/
index e0700bf..6fc96f0 100644 (file)
@@ -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
index 658e6b9..233bbff 100644 (file)
@@ -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/
index 17af6fb..5681685 100644 (file)
@@ -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);
 }
index 395ab81..ce97755 100644 (file)
@@ -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
index ad31203..e428468 100644 (file)
@@ -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)
 {
diff --git a/drivers/dax/pmem/Makefile b/drivers/dax/pmem/Makefile
new file mode 100644 (file)
index 0000000..e2e79bd
--- /dev/null
@@ -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
diff --git a/drivers/dax/pmem/compat.c b/drivers/dax/pmem/compat.c
new file mode 100644 (file)
index 0000000..d7b15e6
--- /dev/null
@@ -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);
similarity index 57%
rename from drivers/dax/pmem.c
rename to drivers/dax/pmem/core.c
index d3cefa7..bdcff1b 100644 (file)
@@ -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);
diff --git a/drivers/dax/pmem/pmem.c b/drivers/dax/pmem/pmem.c
new file mode 100644 (file)
index 0000000..0ae4238
--- /dev/null
@@ -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
index c9b500a..e1286d2 100644 (file)
@@ -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