[PATCH 2/4] btrfs: sysfs, add UUID/devinfo kobject

[Anand Jain <anand.jain@oracle.com>]

Preparatory patch creates kobject /sys/fs/btrfs/UUID/devinfo to hold
btrfs_fs_devices::dev_state attribute.

This is being added in the mount context, that means we don't see
UUID/devinfo before the mount (yet).

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
 fs/btrfs/sysfs.c   | 15 +++++++++++++++
 fs/btrfs/volumes.h |  1 +
 2 files changed, 16 insertions(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 4cda410f0e6b..af169970e818 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -734,6 +734,12 @@ static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
 
 static void __btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 {
+	if (fs_devs->devinfo_kobj) {
+		kobject_del(fs_devs->devinfo_kobj);
+		kobject_put(fs_devs->devinfo_kobj);
+		fs_devs->devinfo_kobj = NULL;
+	}
+
 	if (fs_devs->devices_kobj) {
 		kobject_del(fs_devs->devices_kobj);
 		kobject_put(fs_devs->devices_kobj);
@@ -1080,6 +1086,15 @@ int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs)
 		return -ENOMEM;
 	}
 
+	fs_devs->devinfo_kobj = kobject_create_and_add("devinfo",
+						       &fs_devs->fsid_kobj);
+	if (!fs_devs->devinfo_kobj) {
+		btrfs_err(fs_devs->fs_info,
+			  "failed to init sysfs devinfo kobject");
+		btrfs_sysfs_remove_fsid(fs_devs);
+		return -ENOMEM;
+	}
+
 	return 0;
 }
 
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 3c56ef571b00..38f2e8437b68 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -256,6 +256,7 @@ struct btrfs_fs_devices {
 	/* sysfs kobjects */
 	struct kobject fsid_kobj;
 	struct kobject *devices_kobj;
+	struct kobject *devinfo_kobj;
 	struct completion kobj_unregister;
 };
 
-- 
2.23.0