nilfs2: add /sys/fs/nilfs2/<device>/segctor group

This patch adds creation of /sys/fs/nilfs2/<device>/segctor
group.

The segctor group contains attributes that describe
segctor thread activity details:
(1) last_pseg_block - show start block number of the latest segment.
(2) last_seg_sequence - show sequence value of the latest segment.
(3) last_seg_checkpoint - show checkpoint number of the latest segment.
(4) current_seg_sequence - show segment sequence counter.
(5) current_last_full_seg - show index number of the latest full segment.
(6) next_full_seg - show index number of the full segment index
to be used next.
(7) next_pseg_offset - show offset of next partial segment in
the current full segment.
(8) next_checkpoint - show next checkpoint number.
(9) last_seg_write_time - show write time of the last segment
in human-readable format.
(10) last_seg_write_time_secs - show write time of the last segment
in seconds.
(11) last_nongc_write_time - show write time of the last segment
not for cleaner operation in human-readable format.
(12) last_nongc_write_time_secs - show write time of the last segment
not for cleaner operation in seconds.
(13) dirty_data_blocks_count - show number of dirty data blocks.

Signed-off-by: Vyacheslav Dubeyko <Vyacheslav.Dubeyko@hgst.com>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Michael L. Semon <mlsemon35@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/nilfs2/sysfs.h

@@ -28,11 +28,17 @@
  * struct nilfs_sysfs_dev_subgroups - device subgroup kernel objects
  * @sg_superblock_kobj: /sys/fs/<nilfs>/<device>/superblock
  * @sg_superblock_kobj_unregister: completion state
+ * @sg_segctor_kobj: /sys/fs/<nilfs>/<device>/segctor
+ * @sg_segctor_kobj_unregister: completion state
  */
 struct nilfs_sysfs_dev_subgroups {
 	/* /sys/fs/<nilfs>/<device>/superblock */
 	struct kobject sg_superblock_kobj;
 	struct completion sg_superblock_kobj_unregister;
+
+	/* /sys/fs/<nilfs>/<device>/segctor */
+	struct kobject sg_segctor_kobj;
+	struct completion sg_segctor_kobj_unregister;
 };
 
 #define NILFS_COMMON_ATTR_STRUCT(name) \
@@ -57,6 +63,7 @@ struct nilfs_##name##_attr { \
 
 NILFS_DEV_ATTR_STRUCT(dev);
 NILFS_DEV_ATTR_STRUCT(superblock);
+NILFS_DEV_ATTR_STRUCT(segctor);
 
 #define NILFS_ATTR(type, name, mode, show, store) \
 	static struct nilfs_##type##_attr nilfs_##type##_attr_##name = \
@@ -90,11 +97,20 @@ NILFS_DEV_ATTR_STRUCT(superblock);
 #define NILFS_SUPERBLOCK_RW_ATTR(name) \
 	NILFS_RW_ATTR(superblock, name)
 
+#define NILFS_SEGCTOR_INFO_ATTR(name) \
+	NILFS_INFO_ATTR(segctor, name)
+#define NILFS_SEGCTOR_RO_ATTR(name) \
+	NILFS_RO_ATTR(segctor, name)
+#define NILFS_SEGCTOR_RW_ATTR(name) \
+	NILFS_RW_ATTR(segctor, name)
+
 #define NILFS_FEATURE_ATTR_LIST(name) \
 	(&nilfs_feature_attr_##name.attr)
 #define NILFS_DEV_ATTR_LIST(name) \
 	(&nilfs_dev_attr_##name.attr)
 #define NILFS_SUPERBLOCK_ATTR_LIST(name) \
 	(&nilfs_superblock_attr_##name.attr)
+#define NILFS_SEGCTOR_ATTR_LIST(name) \
+	(&nilfs_segctor_attr_##name.attr)
 
 #endif /* _NILFS_SYSFS_H */