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

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

The superblock group contains attributes that describe
superblock's details:
(1) sb_write_time - show previous write time of super block in
human-readable format.
(2) sb_write_time_secs - show previous write time of super block
in seconds.
(3) sb_write_count - show write count of super block.
(4) sb_update_frequency - show/set interval of periodical update
of superblock (in seconds). You can set preferable frequency of
superblock update by command:

echo <value> > /sys/fs/nilfs2/<device>/superblock/sb_update_frequency

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>

1 files changed, 217 insertions, 1 deletions

diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
index 780d0f5..239f239 100644
--- a/fs/nilfs2/sysfs.c
+++ b/fs/nilfs2/sysfs.c
@@ -41,6 +41,202 @@ static struct kset *nilfs_kset;
 		count; \
 })
 
+#define NILFS_DEV_INT_GROUP_OPS(name, parent_name) \
+static ssize_t nilfs_##name##_attr_show(struct kobject *kobj, \
+					struct attribute *attr, char *buf) \
+{ \
+	struct the_nilfs *nilfs = container_of(kobj->parent, \
+						struct the_nilfs, \
+						ns_##parent_name##_kobj); \
+	struct nilfs_##name##_attr *a = container_of(attr, \
+						struct nilfs_##name##_attr, \
+						attr); \
+	return a->show ? a->show(a, nilfs, buf) : 0; \
+} \
+static ssize_t nilfs_##name##_attr_store(struct kobject *kobj, \
+					 struct attribute *attr, \
+					 const char *buf, size_t len) \
+{ \
+	struct the_nilfs *nilfs = container_of(kobj->parent, \
+						struct the_nilfs, \
+						ns_##parent_name##_kobj); \
+	struct nilfs_##name##_attr *a = container_of(attr, \
+						struct nilfs_##name##_attr, \
+						attr); \
+	return a->store ? a->store(a, nilfs, buf, len) : 0; \
+} \
+static const struct sysfs_ops nilfs_##name##_attr_ops = { \
+	.show	= nilfs_##name##_attr_show, \
+	.store	= nilfs_##name##_attr_store, \
+};
+
+#define NILFS_DEV_INT_GROUP_TYPE(name, parent_name) \
+static void nilfs_##name##_attr_release(struct kobject *kobj) \
+{ \
+	struct nilfs_sysfs_##parent_name##_subgroups *subgroups; \
+	struct the_nilfs *nilfs = container_of(kobj->parent, \
+						struct the_nilfs, \
+						ns_##parent_name##_kobj); \
+	subgroups = nilfs->ns_##parent_name##_subgroups; \
+	complete(&subgroups->sg_##name##_kobj_unregister); \
+} \
+static struct kobj_type nilfs_##name##_ktype = { \
+	.default_attrs	= nilfs_##name##_attrs, \
+	.sysfs_ops	= &nilfs_##name##_attr_ops, \
+	.release	= nilfs_##name##_attr_release, \
+};
+
+#define NILFS_DEV_INT_GROUP_FNS(name, parent_name) \
+int nilfs_sysfs_create_##name##_group(struct the_nilfs *nilfs) \
+{ \
+	struct kobject *parent; \
+	struct kobject *kobj; \
+	struct completion *kobj_unregister; \
+	struct nilfs_sysfs_##parent_name##_subgroups *subgroups; \
+	int err; \
+	subgroups = nilfs->ns_##parent_name##_subgroups; \
+	kobj = &subgroups->sg_##name##_kobj; \
+	kobj_unregister = &subgroups->sg_##name##_kobj_unregister; \
+	parent = &nilfs->ns_##parent_name##_kobj; \
+	kobj->kset = nilfs_kset; \
+	init_completion(kobj_unregister); \
+	err = kobject_init_and_add(kobj, &nilfs_##name##_ktype, parent, \
+				    #name); \
+	if (err) \
+		return err; \
+	return 0; \
+} \
+void nilfs_sysfs_delete_##name##_group(struct the_nilfs *nilfs) \
+{ \
+	kobject_del(&nilfs->ns_##parent_name##_subgroups->sg_##name##_kobj); \
+}
+
+/************************************************************************
+ *                        NILFS superblock attrs                        *
+ ************************************************************************/
+
+static ssize_t
+nilfs_superblock_sb_write_time_show(struct nilfs_superblock_attr *attr,
+				     struct the_nilfs *nilfs,
+				     char *buf)
+{
+	time_t sbwtime;
+
+	down_read(&nilfs->ns_sem);
+	sbwtime = nilfs->ns_sbwtime;
+	up_read(&nilfs->ns_sem);
+
+	return NILFS_SHOW_TIME(sbwtime, buf);
+}
+
+static ssize_t
+nilfs_superblock_sb_write_time_secs_show(struct nilfs_superblock_attr *attr,
+					 struct the_nilfs *nilfs,
+					 char *buf)
+{
+	time_t sbwtime;
+
+	down_read(&nilfs->ns_sem);
+	sbwtime = nilfs->ns_sbwtime;
+	up_read(&nilfs->ns_sem);
+
+	return snprintf(buf, PAGE_SIZE, "%llu\n", (unsigned long long)sbwtime);
+}
+
+static ssize_t
+nilfs_superblock_sb_write_count_show(struct nilfs_superblock_attr *attr,
+				      struct the_nilfs *nilfs,
+				      char *buf)
+{
+	unsigned sbwcount;
+
+	down_read(&nilfs->ns_sem);
+	sbwcount = nilfs->ns_sbwcount;
+	up_read(&nilfs->ns_sem);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", sbwcount);
+}
+
+static ssize_t
+nilfs_superblock_sb_update_frequency_show(struct nilfs_superblock_attr *attr,
+					    struct the_nilfs *nilfs,
+					    char *buf)
+{
+	unsigned sb_update_freq;
+
+	down_read(&nilfs->ns_sem);
+	sb_update_freq = nilfs->ns_sb_update_freq;
+	up_read(&nilfs->ns_sem);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", sb_update_freq);
+}
+
+static ssize_t
+nilfs_superblock_sb_update_frequency_store(struct nilfs_superblock_attr *attr,
+					    struct the_nilfs *nilfs,
+					    const char *buf, size_t count)
+{
+	unsigned val;
+	int err;
+
+	err = kstrtouint(skip_spaces(buf), 0, &val);
+	if (err) {
+		printk(KERN_ERR "NILFS: unable to convert string: err=%d\n",
+			err);
+		return err;
+	}
+
+	if (val < NILFS_SB_FREQ) {
+		val = NILFS_SB_FREQ;
+		printk(KERN_WARNING "NILFS: superblock update frequency cannot be lesser than 10 seconds\n");
+	}
+
+	down_write(&nilfs->ns_sem);
+	nilfs->ns_sb_update_freq = val;
+	up_write(&nilfs->ns_sem);
+
+	return count;
+}
+
+static const char sb_readme_str[] =
+	"The superblock group contains attributes that describe\n"
+	"superblock's details.\n\n"
+	"(1) sb_write_time\n\tshow previous write time of super block "
+	"in human-readable format.\n\n"
+	"(2) sb_write_time_secs\n\tshow previous write time of super block "
+	"in seconds.\n\n"
+	"(3) sb_write_count\n\tshow write count of super block.\n\n"
+	"(4) sb_update_frequency\n"
+	"\tshow/set interval of periodical update of superblock (in seconds).\n\n"
+	"\tYou can set preferable frequency of superblock update by command:\n\n"
+	"\t'echo <val> > /sys/fs/<nilfs>/<dev>/superblock/sb_update_frequency'\n";
+
+static ssize_t
+nilfs_superblock_README_show(struct nilfs_superblock_attr *attr,
+				struct the_nilfs *nilfs, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, sb_readme_str);
+}
+
+NILFS_SUPERBLOCK_RO_ATTR(sb_write_time);
+NILFS_SUPERBLOCK_RO_ATTR(sb_write_time_secs);
+NILFS_SUPERBLOCK_RO_ATTR(sb_write_count);
+NILFS_SUPERBLOCK_RW_ATTR(sb_update_frequency);
+NILFS_SUPERBLOCK_RO_ATTR(README);
+
+static struct attribute *nilfs_superblock_attrs[] = {
+	NILFS_SUPERBLOCK_ATTR_LIST(sb_write_time),
+	NILFS_SUPERBLOCK_ATTR_LIST(sb_write_time_secs),
+	NILFS_SUPERBLOCK_ATTR_LIST(sb_write_count),
+	NILFS_SUPERBLOCK_ATTR_LIST(sb_update_frequency),
+	NILFS_SUPERBLOCK_ATTR_LIST(README),
+	NULL,
+};
+
+NILFS_DEV_INT_GROUP_OPS(superblock, dev);
+NILFS_DEV_INT_GROUP_TYPE(superblock, dev);
+NILFS_DEV_INT_GROUP_FNS(superblock, dev);
+
 /************************************************************************
  *                        NILFS device attrs                            *
  ************************************************************************/
@@ -189,24 +385,44 @@ static struct kobj_type nilfs_dev_ktype = {
 int nilfs_sysfs_create_device_group(struct super_block *sb)
 {
 	struct the_nilfs *nilfs = sb->s_fs_info;
+	size_t devgrp_size = sizeof(struct nilfs_sysfs_dev_subgroups);
 	int err;
 
+	nilfs->ns_dev_subgroups = kzalloc(devgrp_size, GFP_KERNEL);
+	if (unlikely(!nilfs->ns_dev_subgroups)) {
+		err = -ENOMEM;
+		printk(KERN_ERR "NILFS: unable to allocate memory for device group\n");
+		goto failed_create_device_group;
+	}
+
 	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;
+		goto free_dev_subgroups;
+
+	err = nilfs_sysfs_create_superblock_group(nilfs);
+	if (err)
+		goto cleanup_dev_kobject;
 
 	return 0;
 
+cleanup_dev_kobject:
+	kobject_del(&nilfs->ns_dev_kobj);
+
+free_dev_subgroups:
+	kfree(nilfs->ns_dev_subgroups);
+
 failed_create_device_group:
 	return err;
 }
 
 void nilfs_sysfs_delete_device_group(struct the_nilfs *nilfs)
 {
+	nilfs_sysfs_delete_superblock_group(nilfs);
 	kobject_del(&nilfs->ns_dev_kobj);
+	kfree(nilfs->ns_dev_subgroups);
 }
 
 /************************************************************************