[PATCH v3 12/23] device-dax: Add an allocation interface for device-dax instances

Dan Williams
2020-08-01T03:42:30Z

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.

Link: https://lore.kernel.org/linux-nvdimm/x49shpp3zn8.fsf@segfault.boston.devel.redhat.com
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/dax/bus.c | 120 +++++++++++++++++++++++++++++++++++++++++----
drivers/dax/bus.h | 7 ++-
drivers/dax/dax-private.h | 2 -
drivers/dax/hmem/hmem.c | 7 +--
drivers/dax/pmem/core.c | 8 +--
5 files changed, 121 insertions(+), 23 deletions(-)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 96bd64ba95a5..0a48ce378686 100644
--- 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 4aeb36da83a4..44592a8cac0f 100644
--- 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 12a2dbc43b40..99b1273bb232 100644
--- 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 af82d6ba820a..e7b64539e23e 100644
--- 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 4fa81d3d2f65..4fe700884338 100644
--- 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);