A DC dax device's size is determined by the extents that back it, not by
the user. DCD extents are all-or-nothing, so partial shrink is just as
illegal as growing. Enforce that on the size and creation paths:
* size_store: any non-zero resize on a DC region returns -EOPNOTSUPP.
The sole exception is size=0, which daxctl destroy-device writes to
return every claimed extent to the region's available pool before
the device's name is written to the region's 'delete' attribute.
* __devm_create_dev_dax: a DC dax device must be created at size 0.
Non-zero data->size on a DC region returns -EINVAL with a clear
message.
The resize machinery (dev_dax_shrink, adjust_ok, dev_dax_resize_static,
dev_dax_resize) learns to walk the right parent — dax_region->res for
static regions, the dax_resource->res for DC regions claimed via
uuid_store — so shrink-to-0 correctly releases each extent's child
resource rather than the region's.
Based on an original patch by Navneet Singh.
Signed-off-by: Ira Weiny <[email protected]>
Signed-off-by: Anisa Su <[email protected]>
---
Changes:
[anisa: split out from the original "Surface dc_extents" commit;
DC-aware resize policy only.]
---
drivers/dax/bus.c | 46 +++++++++++++++++++++++++++++++++++-----------
1 file changed, 35 insertions(+), 11 deletions(-)
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 1d6f82920be6..c030eb103ad0 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1136,7 +1136,8 @@ static int dev_dax_shrink(struct dev_dax *dev_dax,
resource_size_t size)
int i;
for (i = dev_dax->nr_range - 1; i >= 0; i--) {
- struct range *range = &dev_dax->ranges[i].range;
+ struct dev_dax_range *dev_range = &dev_dax->ranges[i];
+ struct range *range = &dev_range->range;
struct dax_mapping *mapping = dev_dax->ranges[i].mapping;
struct resource *adjust = NULL, *res;
resource_size_t shrink;
@@ -1152,6 +1153,10 @@ static int dev_dax_shrink(struct dev_dax *dev_dax,
resource_size_t size)
continue;
}
+ /*
+ * Partial shrink: forbidden on DC regions, so dev_range
+ * here must belong to a static device.
+ */
for_each_dax_region_resource(dax_region, res)
if (strcmp(res->name, dev_name(dev)) == 0
&& res->start == range->start) {
@@ -1195,19 +1200,21 @@ static bool adjust_ok(struct dev_dax *dev_dax, struct
resource *res)
}
/**
- * dev_dax_resize_static - Expand the device into the unused portion of the
- * region. This may involve adjusting the end of an existing resource, or
- * allocating a new resource.
+ * __dev_dax_resize - Expand the device into the unused portion of the region.
+ * This may involve adjusting the end of an existing resource, or allocating a
+ * new resource.
*
* @parent: parent resource to allocate this range in
* @dev_dax: DAX device to be expanded
* @to_alloc: amount of space to alloc; must be <= space available in @parent
+ * @dax_resource: if dc; the parent resource
*
* Return the amount of space allocated or -ERRNO on failure
*/
-static ssize_t dev_dax_resize_static(struct resource *parent,
- struct dev_dax *dev_dax,
- resource_size_t to_alloc)
+static ssize_t __dev_dax_resize(struct resource *parent,
+ struct dev_dax *dev_dax,
+ resource_size_t to_alloc,
+ struct dax_resource *dax_resource)
{
struct resource *res, *first;
int rc;
@@ -1215,7 +1222,8 @@ static ssize_t dev_dax_resize_static(struct resource
*parent,
first = parent->child;
if (!first) {
rc = alloc_dev_dax_range(parent, dev_dax,
- parent->start, to_alloc, NULL);
+ parent->start, to_alloc,
+ dax_resource);
if (rc)
return rc;
return to_alloc;
@@ -1229,7 +1237,8 @@ static ssize_t dev_dax_resize_static(struct resource
*parent,
if (res == first && res->start > parent->start) {
alloc = min(res->start - parent->start, to_alloc);
rc = alloc_dev_dax_range(parent, dev_dax,
- parent->start, alloc, NULL);
+ parent->start, alloc,
+ dax_resource);
if (rc)
return rc;
return alloc;
@@ -1253,7 +1262,8 @@ static ssize_t dev_dax_resize_static(struct resource
*parent,
return rc;
return alloc;
}
- rc = alloc_dev_dax_range(parent, dev_dax, res->end + 1, alloc,
NULL);
+ rc = alloc_dev_dax_range(parent, dev_dax, res->end + 1, alloc,
+ dax_resource);
if (rc)
return rc;
return alloc;
@@ -1264,6 +1274,13 @@ static ssize_t dev_dax_resize_static(struct resource
*parent,
return 0;
}
+static ssize_t dev_dax_resize_static(struct dax_region *dax_region,
+ struct dev_dax *dev_dax,
+ resource_size_t to_alloc)
+{
+ return __dev_dax_resize(&dax_region->res, dev_dax, to_alloc, NULL);
+}
+
static ssize_t dev_dax_resize(struct dax_region *dax_region,
struct dev_dax *dev_dax, resource_size_t size)
{
@@ -1277,6 +1294,8 @@ static ssize_t dev_dax_resize(struct dax_region
*dax_region,
return -EBUSY;
if (size == dev_size)
return 0;
+ if (size != 0 && is_dynamic(dax_region))
+ return -EOPNOTSUPP;
if (size > dev_size && size - dev_size > avail)
return -ENOSPC;
if (size < dev_size)
@@ -1288,7 +1307,7 @@ static ssize_t dev_dax_resize(struct dax_region
*dax_region,
return -ENXIO;
retry:
- alloc = dev_dax_resize_static(&dax_region->res, dev_dax, to_alloc);
+ alloc = dev_dax_resize_static(dax_region, dev_dax, to_alloc);
if (alloc <= 0)
return alloc;
to_alloc -= alloc;
@@ -1674,6 +1693,11 @@ static struct dev_dax *__devm_create_dev_dax(struct
dev_dax_data *data)
struct device *dev;
int rc;
+ if (is_dynamic(dax_region) && data->size) {
+ dev_err(parent, "DC DAX region devices must be created
initially with 0 size");
+ return ERR_PTR(-EINVAL);
+ }
+
dev_dax = kzalloc_obj(*dev_dax);
if (!dev_dax)
return ERR_PTR(-ENOMEM);
--
2.43.0
