f2fs: remove bulk remove_proc_entry() and unnecessary kobject_del()

Convert to use remove_proc_subtree() and kill kobject_del() directly.
kobject_put() actually covers kobject removal automatically, which is
single stage removal.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/sysfs.c

@@ -1462,25 +1462,14 @@ int f2fs_register_sysfs(struct f2fs_sb_info *sbi)
 
 void f2fs_unregister_sysfs(struct f2fs_sb_info *sbi)
 {
-	if (sbi->s_proc) {
-#ifdef CONFIG_F2FS_IOSTAT
-		remove_proc_entry("iostat_info", sbi->s_proc);
-#endif
-		remove_proc_entry("segment_info", sbi->s_proc);
-		remove_proc_entry("segment_bits", sbi->s_proc);
-		remove_proc_entry("victim_bits", sbi->s_proc);
-		remove_proc_entry("discard_plist_info", sbi->s_proc);
-		remove_proc_entry(sbi->sb->s_id, f2fs_proc_root);
-	}
+	if (sbi->s_proc)
+		remove_proc_subtree(sbi->sb->s_id, f2fs_proc_root);
 
-	kobject_del(&sbi->s_stat_kobj);
 	kobject_put(&sbi->s_stat_kobj);
 	wait_for_completion(&sbi->s_stat_kobj_unregister);
-	kobject_del(&sbi->s_feature_list_kobj);
 	kobject_put(&sbi->s_feature_list_kobj);
 	wait_for_completion(&sbi->s_feature_list_kobj_unregister);
 
-	kobject_del(&sbi->s_kobj);
 	kobject_put(&sbi->s_kobj);
 	wait_for_completion(&sbi->s_kobj_unregister);
 }