[ndctl PATCH 2/8] libdaxctl: add daxctl_region_get_available_size()

[Dan Williams]

Retrieve the available_size attribute for a given dax_region.

As a side effect this rework region->region_path to carry the actual
path without the "dax" class prefix for finding child device-dax
instances.

Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 daxctl/lib/libdaxctl-private.h |    3 ++
 daxctl/lib/libdaxctl.c         |   53 ++++++++++++++++++++++++++++++++++------
 daxctl/lib/libdaxctl.sym       |    6 +++++
 daxctl/libdaxctl.h             |    3 ++
 4 files changed, 57 insertions(+), 8 deletions(-)

diff --git a/daxctl/lib/libdaxctl-private.h b/daxctl/lib/libdaxctl-private.h
index abd78fd4cc52..a2924f1e93f5 100644
--- a/daxctl/lib/libdaxctl-private.h
+++ b/daxctl/lib/libdaxctl-private.h
@@ -18,10 +18,13 @@
 /**
  * struct daxctl_region - container for dax_devices
  */
+#define REGION_BUF_SIZE 50
 struct daxctl_region {
        int id;
        uuid_t uuid;
        int refcount;
+       size_t buf_len;
+       void *region_buf;
        int devices_init;
        char *region_path;
        struct daxctl_ctx *ctx;
diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
index 9d71a2952630..4f6bbc0cd7a6 100644
--- a/daxctl/lib/libdaxctl.c
+++ b/daxctl/lib/libdaxctl.c
@@ -191,10 +191,11 @@ DAXCTL_EXPORT void daxctl_region_unref(struct 
daxctl_region *region)
                return;
 
        ctx = region->ctx;
-       info(ctx, "region%d released\n", region->id);
+       dbg(ctx, "%s: %s\n", __func__, daxctl_region_get_devname(region));
        list_for_each_safe(&region->devices, dev, _d, list)
                free_dev(dev, &region->devices);
        free(region->region_path);
+       free(region->region_buf);
        free(region);
 }
 
@@ -208,7 +209,6 @@ DAXCTL_EXPORT struct daxctl_region 
*daxctl_new_region(struct daxctl_ctx *ctx,
                int id, uuid_t uuid, const char *path)
 {
        struct daxctl_region *region;
-       char *region_path;
 
        region = calloc(1, sizeof(*region));
        if (!region)
@@ -217,16 +217,18 @@ DAXCTL_EXPORT struct daxctl_region 
*daxctl_new_region(struct daxctl_ctx *ctx,
        region->id = id;
        region->refcount = 1;
        uuid_copy(region->uuid, uuid);
-       if (asprintf(&region_path, "%s/dax", path) < 0)
-               region_path = NULL;
-       region->region_path = region_path;
+       region->region_path = strdup(path);
        list_head_init(&region->devices);
+       region->buf_len = strlen(region->region_path) + REGION_BUF_SIZE;
+       region->region_buf = calloc(1, region->buf_len);
 
-       if (!region->region_path) {
+       if (!region->region_path || !region->region_buf) {
                daxctl_region_unref(region);
                region = NULL;
        }
 
+       dbg(ctx, "%s: %s\n", __func__, daxctl_region_get_devname(region));
+
        return region;
 }
 
@@ -295,18 +297,53 @@ DAXCTL_EXPORT int daxctl_region_get_id(struct 
daxctl_region *region)
        return region->id;
 }
 
+DAXCTL_EXPORT const char *daxctl_region_get_devname(struct daxctl_region 
*region)
+{
+        return devpath_to_devname(region->region_path);
+}
+
+DAXCTL_EXPORT unsigned long long daxctl_region_get_available_size(
+               struct daxctl_region *region)
+{
+       struct daxctl_ctx *ctx = daxctl_region_get_ctx(region);
+       char *path = region->region_buf;
+       char buf[SYSFS_ATTR_SIZE], *end;
+       int len = region->buf_len;
+       unsigned long long avail;
+
+       if (snprintf(path, len, "%s/dax_region/available_size",
+                               region->region_path) >= len) {
+               err(ctx, "%s: buffer too small!\n",
+                               daxctl_region_get_devname(region));
+               return 0;
+       }
+
+       if (sysfs_read_attr(ctx, path, buf) < 0)
+               return 0;
+
+       avail = strtoull(buf, &end, 0);
+       if (buf[0] && *end == '\0')
+               return avail;
+       return 0;
+}
+
 static void dax_devices_init(struct daxctl_region *region)
 {
        struct daxctl_ctx *ctx = daxctl_region_get_ctx(region);
        char daxdev_fmt[50];
+       char *region_path;
 
        if (region->devices_init)
                return;
 
        region->devices_init = 1;
        sprintf(daxdev_fmt, "dax%d.", region->id);
-       sysfs_device_parse(ctx, region->region_path, daxdev_fmt, region,
-                       add_dax_dev);
+       if (asprintf(&region_path, "%s/dax", region->region_path) < 0)
+               region_path = NULL;
+       if (region_path)
+               sysfs_device_parse(ctx, region_path, daxdev_fmt, region,
+                               add_dax_dev);
+       free(region_path);
 }
 
 DAXCTL_EXPORT struct daxctl_dev *daxctl_dev_get_first(struct daxctl_region 
*region)
diff --git a/daxctl/lib/libdaxctl.sym b/daxctl/lib/libdaxctl.sym
index bdf3bd7da9b3..6fb11d8757cf 100644
--- a/daxctl/lib/libdaxctl.sym
+++ b/daxctl/lib/libdaxctl.sym
@@ -30,3 +30,9 @@ global:
        daxctl_dev_get_minor;
        daxctl_dev_get_size;
 } LIBNDCTL_1;
+
+LIBDAXCTL_3 {
+global:
+       daxctl_region_get_available_size;
+       daxctl_region_get_devname;
+} LIBNDCTL_2;
diff --git a/daxctl/libdaxctl.h b/daxctl/libdaxctl.h
index fbffe8c538b3..ada20ee1e9dd 100644
--- a/daxctl/libdaxctl.h
+++ b/daxctl/libdaxctl.h
@@ -41,6 +41,9 @@ void daxctl_region_unref(struct daxctl_region *region);
 void daxctl_region_get_uuid(struct daxctl_region *region, uuid_t uu);
 int daxctl_region_get_id(struct daxctl_region *region);
 struct daxctl_ctx *daxctl_region_get_ctx(struct daxctl_region *region);
+unsigned long long daxctl_region_get_available_size(
+               struct daxctl_region *region);
+const char *daxctl_region_get_devname(struct daxctl_region *region);
 
 struct daxctl_dev;
 struct daxctl_dev *daxctl_dev_get_first(struct daxctl_region *region);

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