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

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

The mounted_snapshots group contains group for every
mounted snapshot.

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, 47 insertions, 1 deletions

diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index 5cc735fcc1d5..fc0c961d486a 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -112,6 +112,32 @@ void nilfs_sysfs_delete_##name##_group(struct the_nilfs *nilfs) \
 }
 
 /************************************************************************
+ *                    NILFS mounted snapshots attrs                     *
+ ************************************************************************/
+
+static const char mounted_snapshots_readme_str[] =
+        "The mounted_snapshots group contains group for\n"
+        "every mounted snapshot.\n";
+
+static ssize_t
+nilfs_mounted_snapshots_README_show(struct nilfs_mounted_snapshots_attr *attr,
+                                    struct the_nilfs *nilfs, char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, mounted_snapshots_readme_str);
+}
+
+NILFS_MOUNTED_SNAPSHOTS_RO_ATTR(README);
+
+static struct attribute *nilfs_mounted_snapshots_attrs[] = {
+        NILFS_MOUNTED_SNAPSHOTS_ATTR_LIST(README),
+        NULL,
+};
+
+NILFS_DEV_INT_GROUP_OPS(mounted_snapshots, dev);
+NILFS_DEV_INT_GROUP_TYPE(mounted_snapshots, dev);
+NILFS_DEV_INT_GROUP_FNS(mounted_snapshots, dev);
+
+/************************************************************************
  *                      NILFS checkpoints attrs                         *
  ************************************************************************/
 
@@ -866,10 +892,14 @@ int nilfs_sysfs_create_device_group(struct super_block *sb)
         if (err)
                 goto free_dev_subgroups;
 
-        err = nilfs_sysfs_create_checkpoints_group(nilfs);
+        err = nilfs_sysfs_create_mounted_snapshots_group(nilfs);
         if (err)
                 goto cleanup_dev_kobject;
 
+        err = nilfs_sysfs_create_checkpoints_group(nilfs);
+        if (err)
+                goto delete_mounted_snapshots_group;
+
         err = nilfs_sysfs_create_segments_group(nilfs);
         if (err)
                 goto delete_checkpoints_group;
@@ -893,6 +923,9 @@ delete_segments_group:
 delete_checkpoints_group:
         nilfs_sysfs_delete_checkpoints_group(nilfs);
 
+delete_mounted_snapshots_group:
+        nilfs_sysfs_delete_mounted_snapshots_group(nilfs);
+
 cleanup_dev_kobject:
         kobject_del(&nilfs->ns_dev_kobj);
 
@@ -905,6 +938,7 @@ failed_create_device_group:
 
 void nilfs_sysfs_delete_device_group(struct the_nilfs *nilfs)
 {
+        nilfs_sysfs_delete_mounted_snapshots_group(nilfs);
         nilfs_sysfs_delete_checkpoints_group(nilfs);
         nilfs_sysfs_delete_segments_group(nilfs);
         nilfs_sysfs_delete_superblock_group(nilfs);
diff --git a/fs/nilfs2/sysfs.h b/fs/nilfs2/sysfs.h
index 62f0a0dc78ca..4e84e230e9dd 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_mounted_snapshots_kobj: /sys/fs/<nilfs>/<device>/mounted_snapshots
+ * @sg_mounted_snapshots_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
@@ -44,6 +46,10 @@ struct nilfs_sysfs_dev_subgroups {
         struct kobject sg_segctor_kobj;
         struct completion sg_segctor_kobj_unregister;
 
+        /* /sys/fs/<nilfs>/<device>/mounted_snapshots */
+        struct kobject sg_mounted_snapshots_kobj;
+        struct completion sg_mounted_snapshots_kobj_unregister;
+
         /* /sys/fs/<nilfs>/<device>/checkpoints */
         struct kobject sg_checkpoints_kobj;
         struct completion sg_checkpoints_kobj_unregister;
@@ -75,6 +81,7 @@ struct nilfs_##name##_attr { \
 
 NILFS_DEV_ATTR_STRUCT(dev);
 NILFS_DEV_ATTR_STRUCT(segments);
+NILFS_DEV_ATTR_STRUCT(mounted_snapshots);
 NILFS_DEV_ATTR_STRUCT(checkpoints);
 NILFS_DEV_ATTR_STRUCT(superblock);
 NILFS_DEV_ATTR_STRUCT(segctor);
@@ -111,6 +118,9 @@ NILFS_DEV_ATTR_STRUCT(segctor);
 #define NILFS_SEGMENTS_RW_ATTR(name) \
         NILFS_RW_ATTR(segs_info, name)
 
+#define NILFS_MOUNTED_SNAPSHOTS_RO_ATTR(name) \
+        NILFS_RO_ATTR(mounted_snapshots, name)
+
 #define NILFS_CHECKPOINTS_RO_ATTR(name) \
         NILFS_RO_ATTR(checkpoints, name)
 #define NILFS_CHECKPOINTS_RW_ATTR(name) \
@@ -134,6 +144,8 @@ NILFS_DEV_ATTR_STRUCT(segctor);
         (&nilfs_dev_attr_##name.attr)
 #define NILFS_SEGMENTS_ATTR_LIST(name) \
         (&nilfs_segments_attr_##name.attr)
+#define NILFS_MOUNTED_SNAPSHOTS_ATTR_LIST(name) \
+        (&nilfs_mounted_snapshots_attr_##name.attr)
 #define NILFS_CHECKPOINTS_ATTR_LIST(name) \
         (&nilfs_checkpoints_attr_##name.attr)
 #define NILFS_SUPERBLOCK_ATTR_LIST(name) \