[PATCH ndctl v2 02/10] libdaxctl: add daxctl_dev_set_size()

[Joao Martins <joao.m.martins@oracle.com>]

Add an API for setting the size of a dax device.

This sysfs attribute is only writeable for a dynamic
dax device such as the one exported by hmem.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 daxctl/lib/libdaxctl.c   | 24 ++++++++++++++++++++++++
 daxctl/lib/libdaxctl.sym |  5 +++++
 daxctl/libdaxctl.h       |  1 +
 3 files changed, 30 insertions(+)

diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
index ee4a069eb463..00d5f7fe61ad 100644
--- a/daxctl/lib/libdaxctl.c
+++ b/daxctl/lib/libdaxctl.c
@@ -1019,6 +1019,30 @@ DAXCTL_EXPORT unsigned long long daxctl_dev_get_size(struct daxctl_dev *dev)
 	return dev->size;
 }
 
+DAXCTL_EXPORT int daxctl_dev_set_size(struct daxctl_dev *dev, unsigned long long size)
+{
+	struct daxctl_ctx *ctx = daxctl_dev_get_ctx(dev);
+	char buf[SYSFS_ATTR_SIZE];
+	char *path = dev->dev_buf;
+	int len = dev->buf_len;
+
+	if (snprintf(path, len, "%s/size", dev->dev_path) >= len) {
+		err(ctx, "%s: buffer too small!\n",
+				daxctl_dev_get_devname(dev));
+		return -ENXIO;
+	}
+
+	sprintf(buf, "%#llx\n", size);
+	if (sysfs_write_attr(ctx, path, buf) < 0) {
+		err(ctx, "%s: failed to set size\n",
+				daxctl_dev_get_devname(dev));
+		return -ENXIO;
+	}
+
+	dev->size = size;
+	return 0;
+}
+
 DAXCTL_EXPORT int daxctl_dev_get_target_node(struct daxctl_dev *dev)
 {
 	return dev->target_node;
diff --git a/daxctl/lib/libdaxctl.sym b/daxctl/lib/libdaxctl.sym
index 87d02366a917..d8b4137c76b7 100644
--- a/daxctl/lib/libdaxctl.sym
+++ b/daxctl/lib/libdaxctl.sym
@@ -75,3 +75,8 @@ global:
 	daxctl_memory_is_movable;
 	daxctl_memory_online_no_movable;
 } LIBDAXCTL_6;
+
+LIBDAXCTL_8 {
+global:
+	daxctl_dev_set_size;
+} LIBDAXCTL_7;
diff --git a/daxctl/libdaxctl.h b/daxctl/libdaxctl.h
index 6c545e1f3055..e3d482743cc6 100644
--- a/daxctl/libdaxctl.h
+++ b/daxctl/libdaxctl.h
@@ -68,6 +68,7 @@ int daxctl_dev_get_major(struct daxctl_dev *dev);
 int daxctl_dev_get_minor(struct daxctl_dev *dev);
 unsigned long long daxctl_dev_get_resource(struct daxctl_dev *dev);
 unsigned long long daxctl_dev_get_size(struct daxctl_dev *dev);
+int daxctl_dev_set_size(struct daxctl_dev *dev, unsigned long long size);
 struct daxctl_ctx *daxctl_dev_get_ctx(struct daxctl_dev *dev);
 int daxctl_dev_is_enabled(struct daxctl_dev *dev);
 int daxctl_dev_disable(struct daxctl_dev *dev);
-- 
1.8.3.1
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