linux-kernel - [PATCH 5/8] dax: refactor locking out of size calculation routines

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Date:   Sat, 10 Dec 2016 22:28:51 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-nvdimm@...ts.01.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 5/8] dax: refactor locking out of size calculation routines

In preparation for other callers of these routines make the locking the
responsibility of the caller.

Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/dax/dax.c |   30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index d878a56cf3e3..5b65eaff6ace 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -90,11 +90,11 @@ static unsigned long long dax_region_avail_size(
 	unsigned long long size;
 	struct resource *res;
 
-	mutex_lock(&dax_region->lock);
+	WARN_ON_ONCE(!mutex_is_locked(&dax_region->lock));
+
 	size = resource_size(&dax_region->res);
 	for_each_dax_region_resource(dax_region, res)
 		size -= resource_size(res);
-	mutex_unlock(&dax_region->lock);
 
 	return size;
 }
@@ -107,8 +107,11 @@ static ssize_t available_size_show(struct device *dev,
 
 	device_lock(dev);
 	dax_region = dev_get_drvdata(dev);
-	if (dax_region)
+	if (dax_region) {
+		mutex_lock(&dax_region->lock);
 		rc = sprintf(buf, "%llu\n", dax_region_avail_size(dax_region));
+		mutex_unlock(&dax_region->lock);
+	}
 	device_unlock(dev);
 
 	return rc;
@@ -389,16 +392,31 @@ static struct dax_dev *to_dax_dev(struct device *dev)
 	return container_of(dev, struct dax_dev, dev);
 }
 
-static ssize_t size_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
+static unsigned long long dax_dev_size(struct dax_dev *dax_dev)
 {
-	struct dax_dev *dax_dev = to_dax_dev(dev);
+	struct dax_region *dax_region = dax_dev->region;
 	unsigned long long size = 0;
 	int i;
 
+	WARN_ON_ONCE(!mutex_is_locked(&dax_region->lock));
+
 	for (i = 0; i < dax_dev->num_resources; i++)
 		size += resource_size(dax_dev->res[i]);
 
+	return size;
+}
+
+static ssize_t size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	unsigned long long size;
+	struct dax_dev *dax_dev = to_dax_dev(dev);
+	struct dax_region *dax_region = dax_dev->region;
+
+	mutex_lock(&dax_region->lock);
+	size = dax_dev_size(dax_dev);
+	mutex_unlock(&dax_region->lock);
+
 	return sprintf(buf, "%llu\n", size);
 }
 static DEVICE_ATTR_RO(size);