libnvdimm, dax: introduce device-dax infrastructure

Device DAX is the device-centric analogue of Filesystem DAX
(CONFIG_FS_DAX).  It allows persistent memory ranges to be allocated and
mapped without need of an intervening file system.  This initial
infrastructure arranges for a libnvdimm pfn-device to be represented as
a different device-type so that it can be attached to a driver other
than the pmem driver.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 18 insertions, 1 deletions

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index e5ad5162bf34..c5e3196c45b0 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -1288,6 +1288,8 @@ static ssize_t mode_show(struct device *dev,
                 mode = "safe";
         else if (claim && is_nd_pfn(claim))
                 mode = "memory";
+        else if (claim && is_nd_dax(claim))
+                mode = "dax";
         else if (!claim && pmem_should_map_pages(dev))
                 mode = "memory";
         else
@@ -1379,14 +1381,17 @@ struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
 {
         struct nd_btt *nd_btt = is_nd_btt(dev) ? to_nd_btt(dev) : NULL;
         struct nd_pfn *nd_pfn = is_nd_pfn(dev) ? to_nd_pfn(dev) : NULL;
+        struct nd_dax *nd_dax = is_nd_dax(dev) ? to_nd_dax(dev) : NULL;
         struct nd_namespace_common *ndns = NULL;
         resource_size_t size;
 
-        if (nd_btt || nd_pfn) {
+        if (nd_btt || nd_pfn || nd_dax) {
                 if (nd_btt)
                         ndns = nd_btt->ndns;
                 else if (nd_pfn)
                         ndns = nd_pfn->ndns;
+                else if (nd_dax)
+                        ndns = nd_dax->nd_pfn.ndns;
 
                 if (!ndns)
                         return ERR_PTR(-ENODEV);
@@ -1779,6 +1784,18 @@ void nd_region_create_blk_seed(struct nd_region *nd_region)
                 nd_device_register(nd_region->ns_seed);
 }
 
+void nd_region_create_dax_seed(struct nd_region *nd_region)
+{
+        WARN_ON(!is_nvdimm_bus_locked(&nd_region->dev));
+        nd_region->dax_seed = nd_dax_create(nd_region);
+        /*
+         * Seed creation failures are not fatal, provisioning is simply
+         * disabled until memory becomes available
+         */
+        if (!nd_region->dax_seed)
+                dev_err(&nd_region->dev, "failed to create dax namespace\n");
+}
+
 void nd_region_create_pfn_seed(struct nd_region *nd_region)
 {
         WARN_ON(!is_nvdimm_bus_locked(&nd_region->dev));