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

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

The <device> group contains attributes that describe file
system partition's details:
(1) revision - show NILFS file system revision.
(2) blocksize - show volume block size in bytes.
(3) device_size - show volume size in bytes.
(4) free_blocks - show count of free blocks on volume.
(5) uuid - show volume's UUID.
(6) volume_name - show volume's name.

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>

3 files changed, 194 insertions, 0 deletions

diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index 41b8f7039657..780d0f5bbe88 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -42,6 +42,174 @@ static struct kset *nilfs_kset;
 })
 
 /************************************************************************
+ *                        NILFS device attrs                            *
+ ************************************************************************/
+
+static
+ssize_t nilfs_dev_revision_show(struct nilfs_dev_attr *attr,
+                                struct the_nilfs *nilfs,
+                                char *buf)
+{
+        struct nilfs_super_block **sbp = nilfs->ns_sbp;
+        u32 major = le32_to_cpu(sbp[0]->s_rev_level);
+        u16 minor = le16_to_cpu(sbp[0]->s_minor_rev_level);
+
+        return snprintf(buf, PAGE_SIZE, "%d.%d\n", major, minor);
+}
+
+static
+ssize_t nilfs_dev_blocksize_show(struct nilfs_dev_attr *attr,
+                                 struct the_nilfs *nilfs,
+                                 char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, "%u\n", nilfs->ns_blocksize);
+}
+
+static
+ssize_t nilfs_dev_device_size_show(struct nilfs_dev_attr *attr,
+                                    struct the_nilfs *nilfs,
+                                    char *buf)
+{
+        struct nilfs_super_block **sbp = nilfs->ns_sbp;
+        u64 dev_size = le64_to_cpu(sbp[0]->s_dev_size);
+
+        return snprintf(buf, PAGE_SIZE, "%llu\n", dev_size);
+}
+
+static
+ssize_t nilfs_dev_free_blocks_show(struct nilfs_dev_attr *attr,
+                                   struct the_nilfs *nilfs,
+                                   char *buf)
+{
+        sector_t free_blocks = 0;
+
+        nilfs_count_free_blocks(nilfs, &free_blocks);
+        return snprintf(buf, PAGE_SIZE, "%llu\n",
+                        (unsigned long long)free_blocks);
+}
+
+static
+ssize_t nilfs_dev_uuid_show(struct nilfs_dev_attr *attr,
+                            struct the_nilfs *nilfs,
+                            char *buf)
+{
+        struct nilfs_super_block **sbp = nilfs->ns_sbp;
+
+        return snprintf(buf, PAGE_SIZE, "%pUb\n", sbp[0]->s_uuid);
+}
+
+static
+ssize_t nilfs_dev_volume_name_show(struct nilfs_dev_attr *attr,
+                                    struct the_nilfs *nilfs,
+                                    char *buf)
+{
+        struct nilfs_super_block **sbp = nilfs->ns_sbp;
+
+        return scnprintf(buf, sizeof(sbp[0]->s_volume_name), "%s\n",
+                         sbp[0]->s_volume_name);
+}
+
+static const char dev_readme_str[] =
+        "The <device> group contains attributes that describe file system\n"
+        "partition's details.\n\n"
+        "(1) revision\n\tshow NILFS file system revision.\n\n"
+        "(2) blocksize\n\tshow volume block size in bytes.\n\n"
+        "(3) device_size\n\tshow volume size in bytes.\n\n"
+        "(4) free_blocks\n\tshow count of free blocks on volume.\n\n"
+        "(5) uuid\n\tshow volume's UUID.\n\n"
+        "(6) volume_name\n\tshow volume's name.\n\n";
+
+static ssize_t nilfs_dev_README_show(struct nilfs_dev_attr *attr,
+                                     struct the_nilfs *nilfs,
+                                     char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, dev_readme_str);
+}
+
+NILFS_DEV_RO_ATTR(revision);
+NILFS_DEV_RO_ATTR(blocksize);
+NILFS_DEV_RO_ATTR(device_size);
+NILFS_DEV_RO_ATTR(free_blocks);
+NILFS_DEV_RO_ATTR(uuid);
+NILFS_DEV_RO_ATTR(volume_name);
+NILFS_DEV_RO_ATTR(README);
+
+static struct attribute *nilfs_dev_attrs[] = {
+        NILFS_DEV_ATTR_LIST(revision),
+        NILFS_DEV_ATTR_LIST(blocksize),
+        NILFS_DEV_ATTR_LIST(device_size),
+        NILFS_DEV_ATTR_LIST(free_blocks),
+        NILFS_DEV_ATTR_LIST(uuid),
+        NILFS_DEV_ATTR_LIST(volume_name),
+        NILFS_DEV_ATTR_LIST(README),
+        NULL,
+};
+
+static ssize_t nilfs_dev_attr_show(struct kobject *kobj,
+                                    struct attribute *attr, char *buf)
+{
+        struct the_nilfs *nilfs = container_of(kobj, struct the_nilfs,
+                                                ns_dev_kobj);
+        struct nilfs_dev_attr *a = container_of(attr, struct nilfs_dev_attr,
+                                                attr);
+
+        return a->show ? a->show(a, nilfs, buf) : 0;
+}
+
+static ssize_t nilfs_dev_attr_store(struct kobject *kobj,
+                                    struct attribute *attr,
+                                    const char *buf, size_t len)
+{
+        struct the_nilfs *nilfs = container_of(kobj, struct the_nilfs,
+                                                ns_dev_kobj);
+        struct nilfs_dev_attr *a = container_of(attr, struct nilfs_dev_attr,
+                                                attr);
+
+        return a->store ? a->store(a, nilfs, buf, len) : 0;
+}
+
+static void nilfs_dev_attr_release(struct kobject *kobj)
+{
+        struct the_nilfs *nilfs = container_of(kobj, struct the_nilfs,
+                                                ns_dev_kobj);
+        complete(&nilfs->ns_dev_kobj_unregister);
+}
+
+static const struct sysfs_ops nilfs_dev_attr_ops = {
+        .show   = nilfs_dev_attr_show,
+        .store  = nilfs_dev_attr_store,
+};
+
+static struct kobj_type nilfs_dev_ktype = {
+        .default_attrs  = nilfs_dev_attrs,
+        .sysfs_ops      = &nilfs_dev_attr_ops,
+        .release        = nilfs_dev_attr_release,
+};
+
+int nilfs_sysfs_create_device_group(struct super_block *sb)
+{
+        struct the_nilfs *nilfs = sb->s_fs_info;
+        int err;
+
+        nilfs->ns_dev_kobj.kset = nilfs_kset;
+        init_completion(&nilfs->ns_dev_kobj_unregister);
+        err = kobject_init_and_add(&nilfs->ns_dev_kobj, &nilfs_dev_ktype, NULL,
+                                    "%s", sb->s_id);
+        if (err)
+                goto failed_create_device_group;
+
+        return 0;
+
+failed_create_device_group:
+        return err;
+}
+
+void nilfs_sysfs_delete_device_group(struct the_nilfs *nilfs)
+{
+        kobject_del(&nilfs->ns_dev_kobj);
+}
+
+/************************************************************************
  *                        NILFS feature attrs                           *
  ************************************************************************/
 
diff --git a/fs/nilfs2/sysfs.h b/fs/nilfs2/sysfs.h
index 0aed24661052..2353b28c2796 100644
--- a/fs/nilfs2/sysfs.h
+++ b/fs/nilfs2/sysfs.h
@@ -35,6 +35,17 @@ struct nilfs_##name##_attr { \
 
 NILFS_COMMON_ATTR_STRUCT(feature);
 
+#define NILFS_DEV_ATTR_STRUCT(name) \
+struct nilfs_##name##_attr { \
+        struct attribute attr; \
+        ssize_t (*show)(struct nilfs_##name##_attr *, struct the_nilfs *, \
+                        char *); \
+        ssize_t (*store)(struct nilfs_##name##_attr *, struct the_nilfs *, \
+                         const char *, size_t); \
+};
+
+NILFS_DEV_ATTR_STRUCT(dev);
+
 #define NILFS_ATTR(type, name, mode, show, store) \
         static struct nilfs_##type##_attr nilfs_##type##_attr_##name = \
                 __ATTR(name, mode, show, store)
@@ -55,7 +66,16 @@ NILFS_COMMON_ATTR_STRUCT(feature);
 #define NILFS_FEATURE_RW_ATTR(name) \
         NILFS_RW_ATTR(feature, name)
 
+#define NILFS_DEV_INFO_ATTR(name) \
+        NILFS_INFO_ATTR(dev, name)
+#define NILFS_DEV_RO_ATTR(name) \
+        NILFS_RO_ATTR(dev, name)
+#define NILFS_DEV_RW_ATTR(name) \
+        NILFS_RW_ATTR(dev, name)
+
 #define NILFS_FEATURE_ATTR_LIST(name) \
         (&nilfs_feature_attr_##name.attr)
+#define NILFS_DEV_ATTR_LIST(name) \
+        (&nilfs_dev_attr_##name.attr)
 
 #endif /* _NILFS_SYSFS_H */
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index de8cc53b4a5c..34bc7bd57b0b 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -95,6 +95,8 @@ enum {
  * @ns_inode_size: size of on-disk inode
  * @ns_first_ino: first not-special inode number
  * @ns_crc_seed: seed value of CRC32 calculation
+ * @ns_dev_kobj: /sys/fs/<nilfs>/<device>
+ * @ns_dev_kobj_unregister: completion state
  */
 struct the_nilfs {
         unsigned long           ns_flags;
@@ -188,6 +190,10 @@ struct the_nilfs {
         int                     ns_inode_size;
         int                     ns_first_ino;
         u32                     ns_crc_seed;
+
+        /* /sys/fs/<nilfs>/<device> */
+        struct kobject ns_dev_kobj;
+        struct completion ns_dev_kobj_unregister;
 };
 
 #define THE_NILFS_FNS(bit, name)                                        \