device-dax: add an allocation interface for device-dax instances

In preparation for a facility that enables dax regions to be sub-divided,
introduce infrastructure to track and allocate region capacity.

The new dax_region/available_size attribute is only enabled for volatile
hmem devices, not pmem devices that are defined by nvdimm namespace
boundaries.  This is per Jeff's feedback the last time dynamic device-dax
capacity allocation support was discussed.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Brice Goglin <Brice.Goglin@inria.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jia He <justin.he@arm.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hulk Robot <hulkci@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jason Yan <yanaijie@huawei.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/linux-nvdimm/x49shpp3zn8.fsf@segfault.boston.devel.redhat.com
Link: https://lkml.kernel.org/r/159643101035.4062302.6785857915652647857.stgit@dwillia2-desk3.amr.corp.intel.com
Link: https://lkml.kernel.org/r/160106112801.30709.14601438735305335071.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 96bd64b..0a48ce3 100644 (file)
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -130,6 +130,11 @@ ATTRIBUTE_GROUPS(dax_drv);
 
 static int dax_bus_match(struct device *dev, struct device_driver *drv);
 
+static bool is_static(struct dax_region *dax_region)
+{
+       return (dax_region->res.flags & IORESOURCE_DAX_STATIC) != 0;
+}
+
 static struct bus_type dax_bus_type = {
        .name = "dax",
        .uevent = dax_bus_uevent,
@@ -185,7 +190,48 @@ static ssize_t align_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(align);
 
+#define for_each_dax_region_resource(dax_region, res) \
+       for (res = (dax_region)->res.child; res; res = res->sibling)
+
+static unsigned long long dax_region_avail_size(struct dax_region *dax_region)
+{
+       resource_size_t size = resource_size(&dax_region->res);
+       struct resource *res;
+
+       device_lock_assert(dax_region->dev);
+
+       for_each_dax_region_resource(dax_region, res)
+               size -= resource_size(res);
+       return size;
+}
+
+static ssize_t available_size_show(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct dax_region *dax_region = dev_get_drvdata(dev);
+       unsigned long long size;
+
+       device_lock(dev);
+       size = dax_region_avail_size(dax_region);
+       device_unlock(dev);
+
+       return sprintf(buf, "%llu\n", size);
+}
+static DEVICE_ATTR_RO(available_size);
+
+static umode_t dax_region_visible(struct kobject *kobj, struct attribute *a,
+               int n)
+{
+       struct device *dev = container_of(kobj, struct device, kobj);
+       struct dax_region *dax_region = dev_get_drvdata(dev);
+
+       if (is_static(dax_region) && a == &dev_attr_available_size.attr)
+               return 0;
+       return a->mode;
+}
+
 static struct attribute *dax_region_attributes[] = {
+       &dev_attr_available_size.attr,
        &dev_attr_region_size.attr,
        &dev_attr_align.attr,
        &dev_attr_id.attr,
@@ -195,6 +241,7 @@ static struct attribute *dax_region_attributes[] = {
 static const struct attribute_group dax_region_attribute_group = {
        .name = "dax_region",
        .attrs = dax_region_attributes,
+       .is_visible = dax_region_visible,
 };
 
 static const struct attribute_group *dax_region_attribute_groups[] = {
@@ -226,7 +273,8 @@ static void dax_region_unregister(void *region)
 }
 
 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
-               struct resource *res, int target_node, unsigned int align)
+               struct resource *res, int target_node, unsigned int align,
+               unsigned long flags)
 {
        struct dax_region *dax_region;
 
@@ -249,12 +297,17 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
                return NULL;
 
        dev_set_drvdata(parent, dax_region);
-       memcpy(&dax_region->res, res, sizeof(*res));
        kref_init(&dax_region->kref);
        dax_region->id = region_id;
        dax_region->align = align;
        dax_region->dev = parent;
        dax_region->target_node = target_node;
+       dax_region->res = (struct resource) {
+               .start = res->start,
+               .end = res->end,
+               .flags = IORESOURCE_MEM | flags,
+       };
+
        if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
                kfree(dax_region);
                return NULL;
@@ -267,6 +320,32 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 }
 EXPORT_SYMBOL_GPL(alloc_dax_region);
 
+static int alloc_dev_dax_range(struct dev_dax *dev_dax, resource_size_t size)
+{
+       struct dax_region *dax_region = dev_dax->region;
+       struct resource *res = &dax_region->res;
+       struct device *dev = &dev_dax->dev;
+       struct resource *alloc;
+
+       device_lock_assert(dax_region->dev);
+
+       /* TODO: handle multiple allocations per region */
+       if (res->child)
+               return -ENOMEM;
+
+       alloc = __request_region(res, res->start, size, dev_name(dev), 0);
+
+       if (!alloc)
+               return -ENOMEM;
+
+       dev_dax->range = (struct range) {
+               .start = alloc->start,
+               .end = alloc->end,
+       };
+
+       return 0;
+}
+
 static ssize_t size_show(struct device *dev,
                struct device_attribute *attr, char *buf)
 {
@@ -361,6 +440,15 @@ void kill_dev_dax(struct dev_dax *dev_dax)
 }
 EXPORT_SYMBOL_GPL(kill_dev_dax);
 
+static void free_dev_dax_range(struct dev_dax *dev_dax)
+{
+       struct dax_region *dax_region = dev_dax->region;
+       struct range *range = &dev_dax->range;
+
+       device_lock_assert(dax_region->dev);
+       __release_region(&dax_region->res, range->start, range_len(range));
+}
+
 static void dev_dax_release(struct device *dev)
 {
        struct dev_dax *dev_dax = to_dev_dax(dev);
@@ -385,6 +473,7 @@ static void unregister_dev_dax(void *dev)
        dev_dbg(dev, "%s\n", __func__);
 
        kill_dev_dax(dev_dax);
+       free_dev_dax_range(dev_dax);
        device_del(dev);
        put_device(dev);
 }
@@ -397,7 +486,7 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
        struct dev_dax *dev_dax;
        struct inode *inode;
        struct device *dev;
-       int rc = -ENOMEM;
+       int rc;
 
        if (data->id < 0)
                return ERR_PTR(-EINVAL);
@@ -406,11 +495,25 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
        if (!dev_dax)
                return ERR_PTR(-ENOMEM);
 
+       dev_dax->region = dax_region;
+       dev = &dev_dax->dev;
+       device_initialize(dev);
+       dev_set_name(dev, "dax%d.%d", dax_region->id, data->id);
+
+       rc = alloc_dev_dax_range(dev_dax, data->size);
+       if (rc)
+               goto err_range;
+
        if (data->pgmap) {
+               dev_WARN_ONCE(parent, !is_static(dax_region),
+                       "custom dev_pagemap requires a static dax_region\n");
+
                dev_dax->pgmap = kmemdup(data->pgmap,
                                sizeof(struct dev_pagemap), GFP_KERNEL);
-               if (!dev_dax->pgmap)
+               if (!dev_dax->pgmap) {
+                       rc = -ENOMEM;
                        goto err_pgmap;
+               }
        }
 
        /*
@@ -427,12 +530,7 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
        kill_dax(dax_dev);
 
        /* from here on we're committed to teardown via dev_dax_release() */
-       dev = &dev_dax->dev;
-       device_initialize(dev);
-
        dev_dax->dax_dev = dax_dev;
-       dev_dax->region = dax_region;
-       dev_dax->range = data->range;
        dev_dax->target_node = dax_region->target_node;
        kref_get(&dax_region->kref);
 
@@ -444,7 +542,6 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
                dev->class = dax_class;
        dev->parent = parent;
        dev->type = &dev_dax_type;
-       dev_set_name(dev, "dax%d.%d", dax_region->id, data->id);
 
        rc = device_add(dev);
        if (rc) {
@@ -458,9 +555,12 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
                return ERR_PTR(rc);
 
        return dev_dax;
+
 err_alloc_dax:
        kfree(dev_dax->pgmap);
 err_pgmap:
+       free_dev_dax_range(dev_dax);
+err_range:
        kfree(dev_dax);
 
        return ERR_PTR(rc);

diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index 4aeb36d..44592a8 100644 (file)
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -10,8 +10,11 @@ struct resource;
 struct dax_device;
 struct dax_region;
 void dax_region_put(struct dax_region *dax_region);
+
+#define IORESOURCE_DAX_STATIC (1UL << 0)
 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
-               struct resource *res, int target_node, unsigned int align);
+               struct resource *res, int target_node, unsigned int align,
+               unsigned long flags);
 
 enum dev_dax_subsys {
        DEV_DAX_BUS = 0, /* zeroed dev_dax_data picks this by default */
@@ -22,7 +25,7 @@ struct dev_dax_data {
        struct dax_region *dax_region;
        struct dev_pagemap *pgmap;
        enum dev_dax_subsys subsys;
-       struct range range;
+       resource_size_t size;
        int id;
 };
 

diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index 12a2dbc..99b1273 100644 (file)
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -22,7 +22,7 @@ void dax_bus_exit(void);
  * @kref: to pin while other agents have a need to do lookups
  * @dev: parent device backing this region
  * @align: allocation and mapping alignment for child dax devices
- * @res: physical address range of the region
+ * @res: resource tree to track instance allocations
  */
 struct dax_region {
        int id;

diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index af82d6b..e7b6453 100644 (file)
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -20,17 +20,14 @@ static int dax_hmem_probe(struct platform_device *pdev)
 
        mri = dev->platform_data;
        dax_region = alloc_dax_region(dev, pdev->id, res, mri->target_node,
-                       PMD_SIZE);
+                       PMD_SIZE, 0);
        if (!dax_region)
                return -ENOMEM;
 
        data = (struct dev_dax_data) {
                .dax_region = dax_region,
                .id = 0,
-               .range = {
-                       .start = res->start,
-                       .end = res->end,
-               },
+               .size = resource_size(res),
        };
        dev_dax = devm_create_dev_dax(&data);
        if (IS_ERR(dev_dax))

diff --git a/drivers/dax/pmem/core.c b/drivers/dax/pmem/core.c
index 4fa81d3..4fe7008 100644 (file)
--- a/drivers/dax/pmem/core.c
+++ b/drivers/dax/pmem/core.c
@@ -54,7 +54,8 @@ struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys)
        memcpy(&res, &pgmap.res, sizeof(res));
        res.start += offset;
        dax_region = alloc_dax_region(dev, region_id, &res,
-                       nd_region->target_node, le32_to_cpu(pfn_sb->align));
+                       nd_region->target_node, le32_to_cpu(pfn_sb->align),
+                       IORESOURCE_DAX_STATIC);
        if (!dax_region)
                return ERR_PTR(-ENOMEM);
 
@@ -63,10 +64,7 @@ struct dev_dax *__dax_pmem_probe(struct device *dev, enum dev_dax_subsys subsys)
                .id = id,
                .pgmap = &pgmap,
                .subsys = subsys,
-               .range = {
-                       .start = res.start,
-                       .end = res.end,
-               },
+               .size = resource_size(&res),
        };
        dev_dax = devm_create_dev_dax(&data);