[PATCH v2 1/5] btrfs: sysfs: introduce qgroup global attribute groups

[Qu Wenruo <wqu@suse.com>]

Although we already have info kobject for each qgroup, we don't have
global qgroup info attributes to show things like enabled or
inconsistent flags.

Add this qgroups attribute groups, and the first member is qgroup_flags,
which is a read-only attribute to show human readable qgroup flags.

The path is:
 /sys/fs/btrfs/<uuid>/qgroups/enabled
 /sys/fs/btrfs/<uuid>/qgroups/inconsistent

The output is pretty simple, just 1 or 0, with "\n".

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/sysfs.c | 73 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 69 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index f9eff3b0f77c..e48904666703 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -1820,11 +1820,72 @@ int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info)
 	return error;
 }
 
+static ssize_t qgroup_enabled_show(struct kobject *qgroups_kobj,
+				   struct kobj_attribute *a,
+				   char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent);
+	bool enabled;
+	int ret = 0;
+
+	spin_lock(&fs_info->qgroup_lock);
+	enabled = fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON;
+	spin_unlock(&fs_info->qgroup_lock);
+
+	ret += scnprintf(buf, PAGE_SIZE, "%d\n", enabled);
+	return ret;
+}
+
+BTRFS_ATTR(qgroups, enabled, qgroup_enabled_show);
+
+static ssize_t qgroup_inconsistent_show(struct kobject *qgroups_kobj,
+					struct kobj_attribute *a,
+					char *buf)
+{
+	struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent);
+	bool inconsistent;
+	int ret = 0;
+
+	spin_lock(&fs_info->qgroup_lock);
+	inconsistent = fs_info->qgroup_flags &
+		       BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
+	spin_unlock(&fs_info->qgroup_lock);
+
+	ret += scnprintf(buf, PAGE_SIZE, "%d\n", inconsistent);
+	return ret;
+}
+
+BTRFS_ATTR(qgroups, inconsistent, qgroup_inconsistent_show);
+
+/*
+ * Qgroups global info
+ *
+ * Path: /sys/fs/btrfs/<uuid>/qgroups/
+ */
+static struct attribute *qgroups_attrs[] = {
+	BTRFS_ATTR_PTR(qgroups, enabled),
+	BTRFS_ATTR_PTR(qgroups, inconsistent),
+	NULL
+};
+ATTRIBUTE_GROUPS(qgroups);
+
+static void qgroups_release(struct kobject *kobj)
+{
+	kfree(kobj);
+}
+
+static struct kobj_type qgroups_ktype = {
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = qgroups_groups,
+	.release = qgroups_release,
+};
+
 static inline struct btrfs_fs_info *qgroup_kobj_to_fs_info(struct kobject *kobj)
 {
 	return to_fs_info(kobj->parent->parent);
 }
 
+
 #define QGROUP_ATTR(_member, _show_name)					\
 static ssize_t btrfs_qgroup_show_##_member(struct kobject *qgroup_kobj,		\
 					   struct kobj_attribute *a,		\
@@ -1945,11 +2006,15 @@ int btrfs_sysfs_add_qgroups(struct btrfs_fs_info *fs_info)
 	if (fs_info->qgroups_kobj)
 		return 0;
 
-	fs_info->qgroups_kobj = kobject_create_and_add("qgroups", fsid_kobj);
-	if (!fs_info->qgroups_kobj) {
-		ret = -ENOMEM;
+	fs_info->qgroups_kobj = kmalloc(sizeof(struct kobject), GFP_KERNEL);
+	if (!fs_info->qgroups_kobj)
+		return -ENOMEM;
+
+	ret = kobject_init_and_add(fs_info->qgroups_kobj, &qgroups_ktype,
+				   fsid_kobj, "qgroups");
+	if (ret < 0)
 		goto out;
-	}
+
 	rbtree_postorder_for_each_entry_safe(qgroup, next,
 					     &fs_info->qgroup_tree, node) {
 		ret = btrfs_sysfs_add_one_qgroup(fs_info, qgroup);
-- 
2.34.1