In preparation for a reconfigure-device command, add an interface to
retrieve the 'mode' of a dax device. This will allow the
reconfigure-device command (and via daxctl_dev_to_json(), also
daxctl-list) to print the mode in device listings via a 'daxctl-list'
command or immediately after a mode change.

Add a 'state' attribute to the json listings for devices, since a device
could end up in a state where it is not bound to any driver, and hence,
'disabled'. The state attribute is only displayed for disabled devices.

Cc: Dave Hansen <[email protected]>
Cc: Dan Williams <[email protected]>
Signed-off-by: Vishal Verma <[email protected]>
---
 daxctl/lib/libdaxctl.c   | 37 +++++++++++++++++++++++++++++++++++++
 daxctl/lib/libdaxctl.sym |  1 +
 daxctl/libdaxctl.h       |  1 +
 util/json.c              | 17 +++++++++++++++++
 4 files changed, 56 insertions(+)

diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
index b22df50..9ff6235 100644
--- a/daxctl/lib/libdaxctl.c
+++ b/daxctl/lib/libdaxctl.c
@@ -12,6 +12,8 @@
  */
 #include <stdio.h>
 #include <errno.h>
+#include <limits.h>
+#include <libgen.h>
 #include <stdlib.h>
 #include <dirent.h>
 #include <unistd.h>
@@ -880,6 +882,41 @@ DAXCTL_EXPORT int daxctl_dev_disable(struct daxctl_dev 
*dev)
        return 0;
 }
 
+DAXCTL_EXPORT enum daxctl_dev_mode daxctl_dev_get_mode(struct daxctl_dev *dev)
+{
+       const char *devname = daxctl_dev_get_devname(dev);
+       struct daxctl_ctx *ctx = daxctl_dev_get_ctx(dev);
+       int rc = DAXCTL_DEV_MODE_UNKNOWN;
+       char path[200];
+       const int len = sizeof(path);
+       char *mod_path, *mod_base;
+
+       if (!daxctl_dev_is_enabled(dev))
+               return rc;
+
+       if (snprintf(path, len, "%s/driver/module", dev->dev_path) >= len) {
+               err(ctx, "%s: buffer too small!\n", devname);
+               return -ENXIO;
+       }
+
+       mod_path = realpath(path, NULL);
+       if (!mod_path) {
+               rc = -errno;
+               err(ctx, "%s:  unable to determine module: %s\n", devname,
+                       strerror(errno));
+               return rc;
+       }
+
+       mod_base = basename(mod_path);
+       if (strcmp(mod_base, dax_modules[DAXCTL_DEV_MODE_RAM]) == 0)
+               rc = DAXCTL_DEV_MODE_RAM;
+       else if (strcmp(mod_base, dax_modules[DAXCTL_DEV_MODE_DEVDAX]) == 0)
+               rc = DAXCTL_DEV_MODE_DEVDAX;
+
+       free(mod_path);
+       return rc;
+}
+
 DAXCTL_EXPORT struct daxctl_ctx *daxctl_dev_get_ctx(struct daxctl_dev *dev)
 {
        return dev->region->ctx;
diff --git a/daxctl/lib/libdaxctl.sym b/daxctl/lib/libdaxctl.sym
index 53eb700..9ce5096 100644
--- a/daxctl/lib/libdaxctl.sym
+++ b/daxctl/lib/libdaxctl.sym
@@ -67,4 +67,5 @@ global:
        daxctl_memory_set_online;
        daxctl_memory_set_offline;
        daxctl_memory_is_online;
+       daxctl_dev_get_mode;
 } LIBDAXCTL_5;
diff --git a/daxctl/libdaxctl.h b/daxctl/libdaxctl.h
index a5a2bab..6d1c17d 100644
--- a/daxctl/libdaxctl.h
+++ b/daxctl/libdaxctl.h
@@ -74,6 +74,7 @@ int daxctl_dev_disable(struct daxctl_dev *dev);
 int daxctl_dev_enable_devdax(struct daxctl_dev *dev);
 int daxctl_dev_enable_ram(struct daxctl_dev *dev);
 int daxctl_dev_get_target_node(struct daxctl_dev *dev);
+enum daxctl_dev_mode daxctl_dev_get_mode(struct daxctl_dev *dev);
 
 struct daxctl_memory;
 struct daxctl_memory *daxctl_dev_get_memory(struct daxctl_dev *dev);
diff --git a/util/json.c b/util/json.c
index f521337..1673f1d 100644
--- a/util/json.c
+++ b/util/json.c
@@ -271,6 +271,7 @@ struct json_object *util_daxctl_dev_to_json(struct 
daxctl_dev *dev,
 {
        const char *devname = daxctl_dev_get_devname(dev);
        struct json_object *jdev, *jobj;
+       enum daxctl_dev_mode mode;
        int node;
 
        jdev = json_object_new_object();
@@ -292,6 +293,22 @@ struct json_object *util_daxctl_dev_to_json(struct 
daxctl_dev *dev,
                        json_object_object_add(jdev, "target_node", jobj);
        }
 
+       mode = daxctl_dev_get_mode(dev);
+       if (mode >= 0) {
+               if (mode == DAXCTL_DEV_MODE_RAM)
+                       jobj = json_object_new_string("system-ram");
+               else
+                       jobj = json_object_new_string("devdax");
+               if (jobj)
+                       json_object_object_add(jdev, "mode", jobj);
+       }
+
+       if (!daxctl_dev_is_enabled(dev)) {
+               jobj = json_object_new_string("disabled");
+               if (jobj)
+                       json_object_object_add(jdev, "state", jobj);
+       }
+
        return jdev;
 }
 
-- 
2.20.1

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