On Thu, Jul 05, 2018 at 06:48:25PM -0700, Dan Williams wrote:
> On Thu, Jul 5, 2018 at 6:25 PM, Dan Williams <[email protected]> wrote:
> > So, I liked how simple and straightforward this was, but the unit test
> > reminded me how complicated the free space allocation could be given
> > that we still might need to account for aliased BLK capacity.
> >
> > A few things I now notice:
> >
> > * It is possible for a dpa resource to start before nd_mapping->start
> > and/or end after nd_mapping->size. See the diagram in
> > tools/testing/nvdimm/test/nfit.c
> >
> > * We need to be summing the max extents across all DIMMs in the set
> > while also accounting for this BLK overlap problem that
> > nd_pmem_available_dpa() handles.
> >
> > The original bug arose from the fact that the
> > nd_region_available_dpa() accounts for total busy capacity and the
> > allocation path looks for extents. It would be nice to unify those two
> > functions... or maybe standardize on scan_allocate() everywhere.
>
> I think you can redo this using reserve_free_pmem() and then find the
> largest free space reservation after accounting for blk_max_overlap as
> calculated by nd_region_available_dpa().
>
> reserve_free_pmem() inserts resources into the dpa resource tree with
> the name "pmem-reserve" then you need to filter those against
> blk_max_overlap to find which ones might appear free, but shadowed by
> a BLK allocation on one of the DIMMs in the set. Yes, it allocates
> memory and is heavy handed, but I'm having a hard time thinking of
> something better at the moment.
Okay, I think I follow what you're saying, but let me just see if the
following is what you had in mind before sending a v3:
---
diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index 8d348b22ba45..f30e0c3b0282 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -536,6 +536,31 @@ resource_size_t nd_blk_available_dpa(struct nd_region
*nd_region)
return info.available;
}
+/**
+ * nd_pmem_max_contiguous_dpa - For the given dimm+region, return the max
+ * contiguous unallocated dpa range.
+ * @nd_region: constrain available space check to this reference region
+ * @nd_mapping: container of dpa-resource-root + labels
+ */
+resource_size_t nd_pmem_max_contiguous_dpa(struct nd_region *nd_region,
+ struct nd_mapping *nd_mapping)
+{
+ struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
+ resource_size_t max = 0;
+ struct resource *res;
+
+ if (!ndd)
+ return 0;
+
+ for_each_dpa_resource(ndd, res) {
+ if (strcmp(res->name, "pmem-reserve") != 0)
+ continue;
+ if (resource_size(res) > max)
+ max = resource_size(res);
+ }
+ return max;
+}
+
/**
* nd_pmem_available_dpa - for the given dimm+region account unallocated dpa
* @nd_mapping: container of dpa-resource-root + labels
diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 28afdd668905..ba5120aba9bf 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -836,7 +836,7 @@ static int __reserve_free_pmem(struct device *dev, void
*data)
return 0;
}
-static void release_free_pmem(struct nvdimm_bus *nvdimm_bus,
+void release_free_pmem(struct nvdimm_bus *nvdimm_bus,
struct nd_mapping *nd_mapping)
{
struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
@@ -847,7 +847,7 @@ static void release_free_pmem(struct nvdimm_bus *nvdimm_bus,
nvdimm_free_dpa(ndd, res);
}
-static int reserve_free_pmem(struct nvdimm_bus *nvdimm_bus,
+int reserve_free_pmem(struct nvdimm_bus *nvdimm_bus,
struct nd_mapping *nd_mapping)
{
struct nvdimm *nvdimm = nd_mapping->nvdimm;
@@ -1032,7 +1032,7 @@ static ssize_t __size_store(struct device *dev, unsigned
long long val)
allocated += nvdimm_allocated_dpa(ndd, &label_id);
}
- available = nd_region_available_dpa(nd_region);
+ available = nd_region_contiguous_max(nd_region);
if (val > available + allocated)
return -ENOSPC;
diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index 79274ead54fb..391b97e5c820 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -100,6 +100,15 @@ struct nd_region;
struct nvdimm_drvdata;
struct nd_mapping;
void nd_mapping_free_labels(struct nd_mapping *nd_mapping);
+
+int reserve_free_pmem(struct nvdimm_bus *nvdimm_bus,
+ struct nd_mapping *nd_mapping);
+void release_free_pmem(struct nvdimm_bus *nvdimm_bus,
+ struct nd_mapping *nd_mapping);
+
+resource_size_t nd_pmem_max_contiguous_dpa(struct nd_region *nd_region,
+ struct nd_mapping *nd_mapping);
+resource_size_t nd_region_contiguous_max(struct nd_region *nd_region);
resource_size_t nd_pmem_available_dpa(struct nd_region *nd_region,
struct nd_mapping *nd_mapping, resource_size_t *overlap);
resource_size_t nd_blk_available_dpa(struct nd_region *nd_region);
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index ec3543b83330..48b3bd5219d2 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -357,6 +357,35 @@ static ssize_t set_cookie_show(struct device *dev,
}
static DEVICE_ATTR_RO(set_cookie);
+resource_size_t nd_region_contiguous_max(struct nd_region *nd_region)
+{
+ struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(&nd_region->dev);
+ resource_size_t available = 0;
+ int i, rc;
+
+ WARN_ON(!is_nvdimm_bus_locked(&nd_region->dev));
+ for (i = 0; i < nd_region->ndr_mappings; i++) {
+ struct nd_mapping *nd_mapping = &nd_region->mapping[i];
+ struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
+
+ /* if a dimm is disabled the available capacity is zero */
+ if (!ndd)
+ return 0;
+
+
+ if (is_memory(&nd_region->dev)) {
+ rc = reserve_free_pmem(nvdimm_bus, nd_mapping);
+ if (rc)
+ return 0;
+ available += nd_pmem_max_contiguous_dpa(nd_region,
+ nd_mapping);
+ release_free_pmem(nvdimm_bus, nd_mapping);
+ } else if (is_nd_blk(&nd_region->dev))
+ available += nd_blk_available_dpa(nd_region);
+ }
+ return available;
+}
+
resource_size_t nd_region_available_dpa(struct nd_region *nd_region)
{
resource_size_t blk_max_overlap = 0, available, overlap;
--
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