memremap: change devm_memremap_pages interface to use struct dev_pagemap

This new interface is similar to how struct device (and many others)
work. The caller initializes a 'struct dev_pagemap' as required
and calls 'devm_memremap_pages'. This allows the pagemap structure to
be embedded in another structure and thus container_of can be used. In
this way application specific members can be stored in a containing
struct.

This will be used by the P2P infrastructure and HMM could probably
be cleaned up to use it as well (instead of having it's own, similar
'hmm_devmem_pages_create' function).

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 11 insertions, 9 deletions

diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index 8d8c852ba8f2..31b6ecce4c64 100644
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -21,6 +21,7 @@
 struct dax_pmem {
 	struct device *dev;
 	struct percpu_ref ref;
+	struct dev_pagemap pgmap;
 	struct completion cmp;
 };
 
@@ -69,20 +70,23 @@ static int dax_pmem_probe(struct device *dev)
 	struct nd_namespace_common *ndns;
 	struct nd_dax *nd_dax = to_nd_dax(dev);
 	struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
-	struct vmem_altmap __altmap, *altmap = NULL;
 
 	ndns = nvdimm_namespace_common_probe(dev);
 	if (IS_ERR(ndns))
 		return PTR_ERR(ndns);
 	nsio = to_nd_namespace_io(&ndns->dev);
 
+	dax_pmem = devm_kzalloc(dev, sizeof(*dax_pmem), GFP_KERNEL);
+	if (!dax_pmem)
+		return -ENOMEM;
+
 	/* parse the 'pfn' info block via ->rw_bytes */
 	rc = devm_nsio_enable(dev, nsio);
 	if (rc)
 		return rc;
-	altmap = nvdimm_setup_pfn(nd_pfn, &res, &__altmap);
-	if (IS_ERR(altmap))
-		return PTR_ERR(altmap);
+	rc = nvdimm_setup_pfn(nd_pfn, &dax_pmem->pgmap);
+	if (rc)
+		return rc;
 	devm_nsio_disable(dev, nsio);
 
 	pfn_sb = nd_pfn->pfn_sb;
@@ -94,10 +98,6 @@ static int dax_pmem_probe(struct device *dev)
 		return -EBUSY;
 	}
 
-	dax_pmem = devm_kzalloc(dev, sizeof(*dax_pmem), GFP_KERNEL);
-	if (!dax_pmem)
-		return -ENOMEM;
-
 	dax_pmem->dev = dev;
 	init_completion(&dax_pmem->cmp);
 	rc = percpu_ref_init(&dax_pmem->ref, dax_pmem_percpu_release, 0,
@@ -110,7 +110,8 @@ static int dax_pmem_probe(struct device *dev)
 	if (rc)
 		return rc;
 
-	addr = devm_memremap_pages(dev, &res, &dax_pmem->ref, altmap);
+	dax_pmem->pgmap.ref = &dax_pmem->ref;
+	addr = devm_memremap_pages(dev, &dax_pmem->pgmap);
 	if (IS_ERR(addr))
 		return PTR_ERR(addr);
 
@@ -120,6 +121,7 @@ static int dax_pmem_probe(struct device *dev)
 		return rc;
 
 	/* adjust the dax_region resource to the start of data */
+	memcpy(&res, &dax_pmem->pgmap.res, sizeof(res));
 	res.start += le64_to_cpu(pfn_sb->dataoff);
 
 	rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", &region_id, &id);