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

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

The checkpoints group contains attributes that describe
details about volume's checkpoints:
(1) checkpoints_number - show number of checkpoints on volume.
(2) snapshots_number - show number of snapshots on volume.
(3) last_seg_checkpoint - show checkpoint number of the latest segment.
(4) next_checkpoint - show next checkpoint number.

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>

2 files changed, 136 insertions, 1 deletions

diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index fe8e1411dc6a..5cc735fcc1d5 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -112,6 +112,119 @@ void nilfs_sysfs_delete_##name##_group(struct the_nilfs *nilfs) \
 }
 
 /************************************************************************
+ *                      NILFS checkpoints attrs                         *
+ ************************************************************************/
+
+static ssize_t
+nilfs_checkpoints_checkpoints_number_show(struct nilfs_checkpoints_attr *attr,
+                                            struct the_nilfs *nilfs,
+                                            char *buf)
+{
+        __u64 ncheckpoints;
+        struct nilfs_cpstat cpstat;
+        int err;
+
+        down_read(&nilfs->ns_segctor_sem);
+        err = nilfs_cpfile_get_stat(nilfs->ns_cpfile, &cpstat);
+        up_read(&nilfs->ns_segctor_sem);
+        if (err < 0) {
+                printk(KERN_ERR "NILFS: unable to get checkpoint stat: err=%d\n",
+                        err);
+                return err;
+        }
+
+        ncheckpoints = cpstat.cs_ncps;
+
+        return snprintf(buf, PAGE_SIZE, "%llu\n", ncheckpoints);
+}
+
+static ssize_t
+nilfs_checkpoints_snapshots_number_show(struct nilfs_checkpoints_attr *attr,
+                                        struct the_nilfs *nilfs,
+                                        char *buf)
+{
+        __u64 nsnapshots;
+        struct nilfs_cpstat cpstat;
+        int err;
+
+        down_read(&nilfs->ns_segctor_sem);
+        err = nilfs_cpfile_get_stat(nilfs->ns_cpfile, &cpstat);
+        up_read(&nilfs->ns_segctor_sem);
+        if (err < 0) {
+                printk(KERN_ERR "NILFS: unable to get checkpoint stat: err=%d\n",
+                        err);
+                return err;
+        }
+
+        nsnapshots = cpstat.cs_nsss;
+
+        return snprintf(buf, PAGE_SIZE, "%llu\n", nsnapshots);
+}
+
+static ssize_t
+nilfs_checkpoints_last_seg_checkpoint_show(struct nilfs_checkpoints_attr *attr,
+                                            struct the_nilfs *nilfs,
+                                            char *buf)
+{
+        __u64 last_cno;
+
+        spin_lock(&nilfs->ns_last_segment_lock);
+        last_cno = nilfs->ns_last_cno;
+        spin_unlock(&nilfs->ns_last_segment_lock);
+
+        return snprintf(buf, PAGE_SIZE, "%llu\n", last_cno);
+}
+
+static ssize_t
+nilfs_checkpoints_next_checkpoint_show(struct nilfs_checkpoints_attr *attr,
+                                        struct the_nilfs *nilfs,
+                                        char *buf)
+{
+        __u64 cno;
+
+        down_read(&nilfs->ns_sem);
+        cno = nilfs->ns_cno;
+        up_read(&nilfs->ns_sem);
+
+        return snprintf(buf, PAGE_SIZE, "%llu\n", cno);
+}
+
+static const char checkpoints_readme_str[] =
+        "The checkpoints group contains attributes that describe\n"
+        "details about volume's checkpoints.\n\n"
+        "(1) checkpoints_number\n\tshow number of checkpoints on volume.\n\n"
+        "(2) snapshots_number\n\tshow number of snapshots on volume.\n\n"
+        "(3) last_seg_checkpoint\n"
+        "\tshow checkpoint number of the latest segment.\n\n"
+        "(4) next_checkpoint\n\tshow next checkpoint number.\n\n";
+
+static ssize_t
+nilfs_checkpoints_README_show(struct nilfs_checkpoints_attr *attr,
+                                struct the_nilfs *nilfs, char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, checkpoints_readme_str);
+}
+
+NILFS_CHECKPOINTS_RO_ATTR(checkpoints_number);
+NILFS_CHECKPOINTS_RO_ATTR(snapshots_number);
+NILFS_CHECKPOINTS_RO_ATTR(last_seg_checkpoint);
+NILFS_CHECKPOINTS_RO_ATTR(next_checkpoint);
+NILFS_CHECKPOINTS_RO_ATTR(README);
+
+static struct attribute *nilfs_checkpoints_attrs[] = {
+        NILFS_CHECKPOINTS_ATTR_LIST(checkpoints_number),
+        NILFS_CHECKPOINTS_ATTR_LIST(snapshots_number),
+        NILFS_CHECKPOINTS_ATTR_LIST(last_seg_checkpoint),
+        NILFS_CHECKPOINTS_ATTR_LIST(next_checkpoint),
+        NILFS_CHECKPOINTS_ATTR_LIST(README),
+        NULL,
+};
+
+NILFS_DEV_INT_GROUP_OPS(checkpoints, dev);
+NILFS_DEV_INT_GROUP_TYPE(checkpoints, dev);
+NILFS_DEV_INT_GROUP_FNS(checkpoints, dev);
+
+/************************************************************************
  *                        NILFS segments attrs                          *
  ************************************************************************/
 
@@ -753,10 +866,14 @@ int nilfs_sysfs_create_device_group(struct super_block *sb)
         if (err)
                 goto free_dev_subgroups;
 
-        err = nilfs_sysfs_create_segments_group(nilfs);
+        err = nilfs_sysfs_create_checkpoints_group(nilfs);
         if (err)
                 goto cleanup_dev_kobject;
 
+        err = nilfs_sysfs_create_segments_group(nilfs);
+        if (err)
+                goto delete_checkpoints_group;
+
         err = nilfs_sysfs_create_superblock_group(nilfs);
         if (err)
                 goto delete_segments_group;
@@ -773,6 +890,9 @@ delete_superblock_group:
 delete_segments_group:
         nilfs_sysfs_delete_segments_group(nilfs);
 
+delete_checkpoints_group:
+        nilfs_sysfs_delete_checkpoints_group(nilfs);
+
 cleanup_dev_kobject:
         kobject_del(&nilfs->ns_dev_kobj);
 
@@ -785,6 +905,7 @@ failed_create_device_group:
 
 void nilfs_sysfs_delete_device_group(struct the_nilfs *nilfs)
 {
+        nilfs_sysfs_delete_checkpoints_group(nilfs);
         nilfs_sysfs_delete_segments_group(nilfs);
         nilfs_sysfs_delete_superblock_group(nilfs);
         nilfs_sysfs_delete_segctor_group(nilfs);
diff --git a/fs/nilfs2/sysfs.h b/fs/nilfs2/sysfs.h
index 228bdd14f945..62f0a0dc78ca 100644
--- a/fs/nilfs2/sysfs.h
+++ b/fs/nilfs2/sysfs.h
@@ -30,6 +30,8 @@
  * @sg_superblock_kobj_unregister: completion state
  * @sg_segctor_kobj: /sys/fs/<nilfs>/<device>/segctor
  * @sg_segctor_kobj_unregister: completion state
+ * @sg_checkpoints_kobj: /sys/fs/<nilfs>/<device>/checkpoints
+ * @sg_checkpoints_kobj_unregister: completion state
  * @sg_segments_kobj: /sys/fs/<nilfs>/<device>/segments
  * @sg_segments_kobj_unregister: completion state
  */
@@ -42,6 +44,10 @@ struct nilfs_sysfs_dev_subgroups {
         struct kobject sg_segctor_kobj;
         struct completion sg_segctor_kobj_unregister;
 
+        /* /sys/fs/<nilfs>/<device>/checkpoints */
+        struct kobject sg_checkpoints_kobj;
+        struct completion sg_checkpoints_kobj_unregister;
+
         /* /sys/fs/<nilfs>/<device>/segments */
         struct kobject sg_segments_kobj;
         struct completion sg_segments_kobj_unregister;
@@ -69,6 +75,7 @@ struct nilfs_##name##_attr { \
 
 NILFS_DEV_ATTR_STRUCT(dev);
 NILFS_DEV_ATTR_STRUCT(segments);
+NILFS_DEV_ATTR_STRUCT(checkpoints);
 NILFS_DEV_ATTR_STRUCT(superblock);
 NILFS_DEV_ATTR_STRUCT(segctor);
 
@@ -104,6 +111,11 @@ NILFS_DEV_ATTR_STRUCT(segctor);
 #define NILFS_SEGMENTS_RW_ATTR(name) \
         NILFS_RW_ATTR(segs_info, name)
 
+#define NILFS_CHECKPOINTS_RO_ATTR(name) \
+        NILFS_RO_ATTR(checkpoints, name)
+#define NILFS_CHECKPOINTS_RW_ATTR(name) \
+        NILFS_RW_ATTR(checkpoints, name)
+
 #define NILFS_SUPERBLOCK_RO_ATTR(name) \
         NILFS_RO_ATTR(superblock, name)
 #define NILFS_SUPERBLOCK_RW_ATTR(name) \
@@ -122,6 +134,8 @@ NILFS_DEV_ATTR_STRUCT(segctor);
         (&nilfs_dev_attr_##name.attr)
 #define NILFS_SEGMENTS_ATTR_LIST(name) \
         (&nilfs_segments_attr_##name.attr)
+#define NILFS_CHECKPOINTS_ATTR_LIST(name) \
+        (&nilfs_checkpoints_attr_##name.attr)
 #define NILFS_SUPERBLOCK_ATTR_LIST(name) \
         (&nilfs_superblock_attr_##name.attr)
 #define NILFS_SEGCTOR_ATTR_LIST(name) \