device-dax: Move resource pinning+mapping into the common driver

Move the responsibility of calling devm_request_resource() and
devm_memremap_pages() into the common device-dax driver. This is another
preparatory step to allowing an alternate personality driver for a
device-dax range.

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

5 files changed, 90 insertions, 79 deletions

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 0cff32102c4c..69aae2cbd45f 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2017-2018 Intel Corporation. All rights reserved. */
+#include <linux/memremap.h>
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/dax.h>
@@ -206,7 +207,8 @@ static void unregister_dev_dax(void *dev)
         put_device(dev);
 }
 
-struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id)
+struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id,
+                struct dev_pagemap *pgmap)
 {
         struct device *parent = dax_region->dev;
         struct dax_device *dax_dev;
@@ -222,6 +224,8 @@ struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id)
         if (!dev_dax)
                 return ERR_PTR(-ENOMEM);
 
+        memcpy(&dev_dax->pgmap, pgmap, sizeof(*pgmap));
+
         /*
          * No 'host' or dax_operations since there is no access to this
          * device outside of mmap of the resulting character device.
diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index ea509504df3a..e08e0c394983 100644
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -10,7 +10,8 @@ struct dax_region;
 void dax_region_put(struct dax_region *dax_region);
 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
                 struct resource *res, unsigned int align, unsigned long flags);
-struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id);
+struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region, int id,
+                struct dev_pagemap *pgmap);
 int __dax_driver_register(struct device_driver *drv,
                 struct module *module, const char *mod_name);
 #define dax_driver_register(driver) \
diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index c3a121700837..a82ce48f5884 100644
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -42,15 +42,22 @@ struct dax_region {
 };
 
 /**
- * struct dev_dax - instance data for a subdivision of a dax region
+ * struct dev_dax - instance data for a subdivision of a dax region, and
+ * data while the device is activated in the driver.
  * @region - parent region
  * @dax_dev - core dax functionality
  * @dev - device core
+ * @pgmap - pgmap for memmap setup / lifetime (driver owned)
+ * @ref: pgmap reference count (driver owned)
+ * @cmp: @ref final put completion (driver owned)
  */
 struct dev_dax {
         struct dax_region *region;
         struct dax_device *dax_dev;
         struct device dev;
+        struct dev_pagemap pgmap;
+        struct percpu_ref ref;
+        struct completion cmp;
 };
 
 static inline struct dev_dax *to_dev_dax(struct device *dev)
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index f55829404a24..6ad964d7b077 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright(c) 2016-2018 Intel Corporation. All rights reserved. */
+#include <linux/memremap.h>
 #include <linux/pagemap.h>
 #include <linux/module.h>
 #include <linux/device.h>
@@ -13,6 +14,38 @@
 #include "dax-private.h"
 #include "bus.h"
 
+static struct dev_dax *ref_to_dev_dax(struct percpu_ref *ref)
+{
+        return container_of(ref, struct dev_dax, ref);
+}
+
+static void dev_dax_percpu_release(struct percpu_ref *ref)
+{
+        struct dev_dax *dev_dax = ref_to_dev_dax(ref);
+
+        dev_dbg(&dev_dax->dev, "%s\n", __func__);
+        complete(&dev_dax->cmp);
+}
+
+static void dev_dax_percpu_exit(void *data)
+{
+        struct percpu_ref *ref = data;
+        struct dev_dax *dev_dax = ref_to_dev_dax(ref);
+
+        dev_dbg(&dev_dax->dev, "%s\n", __func__);
+        wait_for_completion(&dev_dax->cmp);
+        percpu_ref_exit(ref);
+}
+
+static void dev_dax_percpu_kill(struct percpu_ref *data)
+{
+        struct percpu_ref *ref = data;
+        struct dev_dax *dev_dax = ref_to_dev_dax(ref);
+
+        dev_dbg(&dev_dax->dev, "%s\n", __func__);
+        percpu_ref_kill(ref);
+}
+
 static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
                 const char *func)
 {
@@ -416,10 +449,38 @@ static int dev_dax_probe(struct device *dev)
 {
         struct dev_dax *dev_dax = to_dev_dax(dev);
         struct dax_device *dax_dev = dev_dax->dax_dev;
+        struct resource *res = &dev_dax->region->res;
         struct inode *inode;
         struct cdev *cdev;
+        void *addr;
         int rc;
 
+        /* 1:1 map region resource range to device-dax instance range */
+        if (!devm_request_mem_region(dev, res->start, resource_size(res),
+                                dev_name(dev))) {
+                dev_warn(dev, "could not reserve region %pR\n", res);
+                return -EBUSY;
+        }
+
+        init_completion(&dev_dax->cmp);
+        rc = percpu_ref_init(&dev_dax->ref, dev_dax_percpu_release, 0,
+                        GFP_KERNEL);
+        if (rc)
+                return rc;
+
+        rc = devm_add_action_or_reset(dev, dev_dax_percpu_exit, &dev_dax->ref);
+        if (rc)
+                return rc;
+
+        dev_dax->pgmap.ref = &dev_dax->ref;
+        dev_dax->pgmap.kill = dev_dax_percpu_kill;
+        addr = devm_memremap_pages(dev, &dev_dax->pgmap);
+        if (IS_ERR(addr)) {
+                devm_remove_action(dev, dev_dax_percpu_exit, &dev_dax->ref);
+                percpu_ref_exit(&dev_dax->ref);
+                return PTR_ERR(addr);
+        }
+
         inode = dax_inode(dax_dev);
         cdev = inode->i_cdev;
         cdev_init(cdev, &dax_fops);
diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index e1b50d8fd1f8..d3cefa7868ac 100644
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -18,54 +18,16 @@
 #include "../nvdimm/nd.h"
 #include "bus.h"
 
-struct dax_pmem {
-        struct device *dev;
-        struct percpu_ref ref;
-        struct dev_pagemap pgmap;
-        struct completion cmp;
-};
-
-static struct dax_pmem *to_dax_pmem(struct percpu_ref *ref)
-{
-        return container_of(ref, struct dax_pmem, ref);
-}
-
-static void dax_pmem_percpu_release(struct percpu_ref *ref)
-{
-        struct dax_pmem *dax_pmem = to_dax_pmem(ref);
-
-        dev_dbg(dax_pmem->dev, "trace\n");
-        complete(&dax_pmem->cmp);
-}
-
-static void dax_pmem_percpu_exit(void *data)
-{
-        struct percpu_ref *ref = data;
-        struct dax_pmem *dax_pmem = to_dax_pmem(ref);
-
-        dev_dbg(dax_pmem->dev, "trace\n");
-        wait_for_completion(&dax_pmem->cmp);
-        percpu_ref_exit(ref);
-}
-
-static void dax_pmem_percpu_kill(struct percpu_ref *ref)
-{
-        struct dax_pmem *dax_pmem = to_dax_pmem(ref);
-
-        dev_dbg(dax_pmem->dev, "trace\n");
-        percpu_ref_kill(ref);
-}
-
 static int dax_pmem_probe(struct device *dev)
 {
-        void *addr;
         struct resource res;
         int rc, id, region_id;
+        resource_size_t offset;
         struct nd_pfn_sb *pfn_sb;
         struct dev_dax *dev_dax;
-        struct dax_pmem *dax_pmem;
         struct nd_namespace_io *nsio;
         struct dax_region *dax_region;
+        struct dev_pagemap pgmap = { 0 };
         struct nd_namespace_common *ndns;
         struct nd_dax *nd_dax = to_nd_dax(dev);
         struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
@@ -75,61 +37,37 @@ static int dax_pmem_probe(struct device *dev)
                 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;
-        rc = nvdimm_setup_pfn(nd_pfn, &dax_pmem->pgmap);
+        rc = nvdimm_setup_pfn(nd_pfn, &pgmap);
         if (rc)
                 return rc;
         devm_nsio_disable(dev, nsio);
 
-        pfn_sb = nd_pfn->pfn_sb;
-
-        if (!devm_request_mem_region(dev, nsio->res.start,
-                                resource_size(&nsio->res),
+        /* reserve the metadata area, device-dax will reserve the data */
+        pfn_sb = nd_pfn->pfn_sb;
+        offset = le64_to_cpu(pfn_sb->dataoff);
+        if (!devm_request_mem_region(dev, nsio->res.start, offset,
                                 dev_name(&ndns->dev))) {
-                dev_warn(dev, "could not reserve region %pR\n", &nsio->res);
-                return -EBUSY;
-        }
-
-        dax_pmem->dev = dev;
-        init_completion(&dax_pmem->cmp);
-        rc = percpu_ref_init(&dax_pmem->ref, dax_pmem_percpu_release, 0,
-                        GFP_KERNEL);
-        if (rc)
-                return rc;
-
-        rc = devm_add_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref);
-        if (rc) {
-                percpu_ref_exit(&dax_pmem->ref);
-                return rc;
-        }
-
-        dax_pmem->pgmap.ref = &dax_pmem->ref;
-        dax_pmem->pgmap.kill = dax_pmem_percpu_kill;
-        addr = devm_memremap_pages(dev, &dax_pmem->pgmap);
-        if (IS_ERR(addr))
-                return PTR_ERR(addr);
-
-        /* 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);
+                dev_warn(dev, "could not reserve metadata\n");
+                return -EBUSY;
+        }
 
         rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", &region_id, &id);
         if (rc != 2)
                 return -EINVAL;
 
+        /* adjust the dax_region resource to the start of data */
+        memcpy(&res, &pgmap.res, sizeof(res));
+        res.start += offset;
         dax_region = alloc_dax_region(dev, region_id, &res,
                         le32_to_cpu(pfn_sb->align), PFN_DEV|PFN_MAP);
         if (!dax_region)
                 return -ENOMEM;
 
-        dev_dax = devm_create_dev_dax(dax_region, id);
+        dev_dax = devm_create_dev_dax(dax_region, id, &pgmap);
 
         /* child dev_dax instances now own the lifetime of the dax_region */
         dax_region_put(dax_region);