[PATCH ndctl v1 06/10] libdaxctl: add daxctl_region_create_dev()

[Joao Martins]

Add an API to create an empty seed 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.mart...@oracle.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 daxctl/lib/libdaxctl.c   | 26 ++++++++++++++++++++++++++
 daxctl/lib/libdaxctl.sym |  1 +
 daxctl/libdaxctl.h       |  1 +
 3 files changed, 28 insertions(+)

diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
index 00d5f7fe61ad..d17ff7a02bad 100644
--- a/daxctl/lib/libdaxctl.c
+++ b/daxctl/lib/libdaxctl.c
@@ -583,6 +583,32 @@ DAXCTL_EXPORT unsigned long long 
daxctl_region_get_available_size(
        return 0;
 }
 
+DAXCTL_EXPORT int daxctl_region_create_dev(struct daxctl_region *region)
+{
+       struct daxctl_ctx *ctx = daxctl_region_get_ctx(region);
+       char *path = region->region_buf;
+       int rc, len = region->buf_len;
+       char *num_devices;
+
+       if (snprintf(path, len, "%s/%s/create", region->region_path, attrs) >= 
len) {
+               err(ctx, "%s: buffer too small!\n",
+                               daxctl_region_get_devname(region));
+               return -EFAULT;
+       }
+
+       if (asprintf(&num_devices, "%d", 1) < 0) {
+               err(ctx, "%s: buffer too small!\n",
+                               daxctl_region_get_devname(region));
+               return -EFAULT;
+       }
+
+       rc = sysfs_write_attr(ctx, path, num_devices);
+       if (rc)
+               return rc;
+
+       return 0;
+}
+
 DAXCTL_EXPORT struct daxctl_dev *daxctl_region_get_dev_seed(
                struct daxctl_region *region)
 {
diff --git a/daxctl/lib/libdaxctl.sym b/daxctl/lib/libdaxctl.sym
index d8b4137c76b7..26987ba021ab 100644
--- a/daxctl/lib/libdaxctl.sym
+++ b/daxctl/lib/libdaxctl.sym
@@ -79,4 +79,5 @@ global:
 LIBDAXCTL_8 {
 global:
        daxctl_dev_set_size;
+       daxctl_region_create_dev;
 } LIBDAXCTL_7;
diff --git a/daxctl/libdaxctl.h b/daxctl/libdaxctl.h
index e3d482743cc6..a579ddd1d43c 100644
--- a/daxctl/libdaxctl.h
+++ b/daxctl/libdaxctl.h
@@ -56,6 +56,7 @@ unsigned long daxctl_region_get_align(struct daxctl_region 
*region);
 const char *daxctl_region_get_devname(struct daxctl_region *region);
 const char *daxctl_region_get_path(struct daxctl_region *region);
 
+int daxctl_region_create_dev(struct daxctl_region *region);
 struct daxctl_dev *daxctl_region_get_dev_seed(struct daxctl_region *region);
 
 struct daxctl_dev;
-- 
2.17.1
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