Print the usable size of a BTT namespace after removing driver overhead
in the json for listing/creating a BTT namespace. This makes it
consistent with other flavors of namespaces (dax, pfn).

Cc: Dan Williams <[email protected]>
Reported-by: Linda Knippers <[email protected]>
Signed-off-by: Vishal Verma <[email protected]>
---

v2:
- For a create-namespace command, size was not shown as expected, and as
  it did for 'ndctl list'. This was because after creating the namespace,
  the 'size' field in the existing list of BTTs in libndctl needed to be
  updated with the new value found in sysfs. Add this missing update.

 ndctl/lib/libndctl.c   | 14 ++++++++++++++
 ndctl/lib/libndctl.sym |  1 +
 ndctl/libndctl.h.in    |  1 +
 ndctl/util/json.c      |  1 +
 4 files changed, 17 insertions(+)

diff --git a/ndctl/lib/libndctl.c b/ndctl/lib/libndctl.c
index 0722f79..8ad62c6 100644
--- a/ndctl/lib/libndctl.c
+++ b/ndctl/lib/libndctl.c
@@ -271,6 +271,7 @@ struct ndctl_namespace {
  * struct ndctl_btt - stacked block device provided sector atomicity
  * @module: kernel module (nd_btt)
  * @lbasize: sector size info
+ * @size: usable size of the btt after removing metadata etc
  * @ndns: host namespace for the btt instance
  * @region: parent region
  * @btt_path: btt devpath
@@ -284,6 +285,7 @@ struct ndctl_btt {
        struct ndctl_namespace *ndns;
        struct list_node list;
        struct ndctl_lbasize lbasize;
+       unsigned long long size;
        char *btt_path;
        char *btt_buf;
        char *bdev;
@@ -3614,9 +3616,16 @@ static int add_btt(void *parent, int id, const char 
*btt_base)
        if (parse_lbasize_supported(ctx, devname, buf, &btt->lbasize) < 0)
                goto err_read;
 
+       sprintf(path, "%s/size", btt_base);
+       if (sysfs_read_attr(ctx, path, buf) < 0)
+               btt->size = ULLONG_MAX;
+       else
+               btt->size = strtoull(buf, NULL, 0);
+
        free(path);
        ndctl_btt_foreach(region, btt_dup)
                if (btt->id == btt_dup->id) {
+                       btt_dup->size = btt->size;
                        free_btt(btt, NULL);
                        return 1;
                }
@@ -3705,6 +3714,11 @@ NDCTL_EXPORT void ndctl_btt_get_uuid(struct ndctl_btt 
*btt, uuid_t uu)
        memcpy(uu, btt->uuid, sizeof(uuid_t));
 }
 
+NDCTL_EXPORT unsigned long long ndctl_btt_get_size(struct ndctl_btt *btt)
+{
+       return btt->size;
+}
+
 NDCTL_EXPORT int ndctl_btt_set_uuid(struct ndctl_btt *btt, uuid_t uu)
 {
        struct ndctl_ctx *ctx = ndctl_btt_get_ctx(btt);
diff --git a/ndctl/lib/libndctl.sym b/ndctl/lib/libndctl.sym
index 6af267a..b5d2866 100644
--- a/ndctl/lib/libndctl.sym
+++ b/ndctl/lib/libndctl.sym
@@ -196,6 +196,7 @@ global:
        ndctl_btt_get_num_sector_sizes;
        ndctl_btt_get_namespace;
        ndctl_btt_get_uuid;
+       ndctl_btt_get_size;
        ndctl_btt_is_enabled;
        ndctl_btt_is_valid;
        ndctl_btt_get_devname;
diff --git a/ndctl/libndctl.h.in b/ndctl/libndctl.h.in
index 9e0e82a..451466a 100644
--- a/ndctl/libndctl.h.in
+++ b/ndctl/libndctl.h.in
@@ -521,6 +521,7 @@ unsigned int ndctl_btt_get_sector_size(struct ndctl_btt 
*btt);
 int ndctl_btt_get_num_sector_sizes(struct ndctl_btt *btt);
 struct ndctl_namespace *ndctl_btt_get_namespace(struct ndctl_btt *btt);
 void ndctl_btt_get_uuid(struct ndctl_btt *btt, uuid_t uu);
+unsigned long long ndctl_btt_get_size(struct ndctl_btt *btt);
 int ndctl_btt_is_enabled(struct ndctl_btt *btt);
 int ndctl_btt_is_valid(struct ndctl_btt *btt);
 const char *ndctl_btt_get_devname(struct ndctl_btt *btt);
diff --git a/ndctl/util/json.c b/ndctl/util/json.c
index a9c096c..c727bc2 100644
--- a/ndctl/util/json.c
+++ b/ndctl/util/json.c
@@ -174,6 +174,7 @@ struct json_object *util_namespace_to_json(struct 
ndctl_namespace *ndns)
                break;
        case NDCTL_NS_MODE_SAFE:
                jobj = json_object_new_string("sector");
+               size = ndctl_btt_get_size(btt);
                break;
        case NDCTL_NS_MODE_RAW:
                size = ndctl_namespace_get_size(ndns);
-- 
2.7.4

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