add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/dax/bus.c
..
..
@@ -398,23 +398,39 @@
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 	dev_dbg(dev, "%s\n", __func__);
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 	kill_dev_dax(dev_dax);
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-	free_dev_dax_ranges(dev_dax);
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 	device_del(dev);
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+	free_dev_dax_ranges(dev_dax);
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 	put_device(dev);
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 }
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+
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+static void dax_region_free(struct kref *kref)
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+{
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+	struct dax_region *dax_region;
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+
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+	dax_region = container_of(kref, struct dax_region, kref);
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+	kfree(dax_region);
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+}
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+
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+void dax_region_put(struct dax_region *dax_region)
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+{
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+	kref_put(&dax_region->kref, dax_region_free);
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+}
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+EXPORT_SYMBOL_GPL(dax_region_put);
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 /* a return value >= 0 indicates this invocation invalidated the id */
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 static int __free_dev_dax_id(struct dev_dax *dev_dax)
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 {
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-	struct dax_region *dax_region = dev_dax->region;
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 	struct device *dev = &dev_dax->dev;
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+	struct dax_region *dax_region;
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 	int rc = dev_dax->id;
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 	device_lock_assert(dev);
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-	if (is_static(dax_region) || dev_dax->id < 0)
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+	if (!dev_dax->dyn_id || dev_dax->id < 0)
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 		return -1;
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+	dax_region = dev_dax->region;
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 	ida_free(&dax_region->ida, dev_dax->id);
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+	dax_region_put(dax_region);
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 	dev_dax->id = -1;
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 	return rc;
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 }
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@@ -428,6 +444,20 @@
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 	rc = __free_dev_dax_id(dev_dax);
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 	device_unlock(dev);
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 	return rc;
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+}
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+
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+static int alloc_dev_dax_id(struct dev_dax *dev_dax)
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+{
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+	struct dax_region *dax_region = dev_dax->region;
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+	int id;
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+
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+	id = ida_alloc(&dax_region->ida, GFP_KERNEL);
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+	if (id < 0)
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+		return id;
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+	kref_get(&dax_region->kref);
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+	dev_dax->dyn_id = true;
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+	dev_dax->id = id;
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+	return id;
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 }
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 static ssize_t delete_store(struct device *dev, struct device_attribute *attr,
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@@ -517,20 +547,6 @@
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 	NULL,
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 };
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549
 
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-static void dax_region_free(struct kref *kref)
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-{
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-	struct dax_region *dax_region;
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-
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-	dax_region = container_of(kref, struct dax_region, kref);
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-	kfree(dax_region);
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-}
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-
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-void dax_region_put(struct dax_region *dax_region)
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-{
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-	kref_put(&dax_region->kref, dax_region_free);
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-}
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-EXPORT_SYMBOL_GPL(dax_region_put);
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-
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 static void dax_region_unregister(void *region)
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 {
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 	struct dax_region *dax_region = region;
..
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@@ -592,10 +608,12 @@
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 static void dax_mapping_release(struct device *dev)
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 {
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 	struct dax_mapping *mapping = to_dax_mapping(dev);
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-	struct dev_dax *dev_dax = to_dev_dax(dev->parent);
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+	struct device *parent = dev->parent;
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+	struct dev_dax *dev_dax = to_dev_dax(parent);
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 	ida_free(&dev_dax->ida, mapping->id);
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 	kfree(mapping);
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+	put_device(parent);
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 }
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 static void unregister_dax_mapping(void *data)
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@@ -735,6 +753,7 @@
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 	dev = &mapping->dev;
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 	device_initialize(dev);
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 	dev->parent = &dev_dax->dev;
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+	get_device(dev->parent);
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 	dev->type = &dax_mapping_type;
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 	dev_set_name(dev, "mapping%d", mapping->id);
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 	rc = device_add(dev);
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@@ -1267,12 +1286,10 @@
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 static void dev_dax_release(struct device *dev)
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 {
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 	struct dev_dax *dev_dax = to_dev_dax(dev);
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-	struct dax_region *dax_region = dev_dax->region;
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 	struct dax_device *dax_dev = dev_dax->dax_dev;
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 	put_dax(dax_dev);
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 	free_dev_dax_id(dev_dax);
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-	dax_region_put(dax_region);
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 	kfree(dev_dax->pgmap);
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 	kfree(dev_dax);
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 }
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@@ -1296,6 +1313,7 @@
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 	if (!dev_dax)
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 		return ERR_PTR(-ENOMEM);
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+	dev_dax->region = dax_region;
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 	if (is_static(dax_region)) {
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 		if (dev_WARN_ONCE(parent, data->id < 0,
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 				"dynamic id specified to static region\n")) {
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@@ -1311,13 +1329,11 @@
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 			goto err_id;
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 		}
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-		rc = ida_alloc(&dax_region->ida, GFP_KERNEL);
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+		rc = alloc_dev_dax_id(dev_dax);
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 		if (rc < 0)
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 			goto err_id;
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-		dev_dax->id = rc;
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 	}
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-	dev_dax->region = dax_region;
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 	dev = &dev_dax->dev;
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 	device_initialize(dev);
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 	dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id);
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@@ -1355,7 +1371,6 @@
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 	dev_dax->target_node = dax_region->target_node;
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 	dev_dax->align = dax_region->align;
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 	ida_init(&dev_dax->ida);
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-	kref_get(&dax_region->kref);
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 	inode = dax_inode(dax_dev);
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 	dev->devt = inode->i_rdev;