[PATCH v3 1/9] nilfs2: add /sys/fs/nilfs2/features group

[Vyacheslav Dubeyko]

From: Vyacheslav Dubeyko <Vyacheslav.Dubeyko-***@public.gmane.org>
Subject: [PATCH v3 1/9] nilfs2: add /sys/fs/nilfs2/features group

This patch adds code of creation /sys/fs/nilfs2 group and
/sys/fs/nilfs2/features group.

The features group contains attributes that describe NILFS
file system driver features:
(1) revision - show current revision of NILFS file system driver.

There are two formats of timestamp output - seconds and
human-readable format. Every showed timestamp has two sysfs
files (time-<xxx> and time-<xxx>-secs). One sysfs file
(time-<xxx>) shows time in human-readable format. Another
sysfs file (time-<xxx>-secs) shows time in seconds.

It was reported by Michael L. Semon <mlsemon35-***@public.gmane.org> that
timestamp output in human-readable format should be changed
from "2014-4-12 14:5:38" to "2014-04-12 14:05:38". Second
version of the patch fixes this issue.

Reported-by: Michael L. Semon <mlsemon35-***@public.gmane.org>
Signed-off-by: Vyacheslav Dubeyko <Vyacheslav.Dubeyko-***@public.gmane.org>
CC: Vyacheslav Dubeyko <slava-***@public.gmane.org>
CC: Ryusuke Konishi <konishi.ryusuke-***@public.gmane.org>
---
Documentation/ABI/testing/sysfs-fs-nilfs2 | 16 ++++
fs/nilfs2/sysfs.c | 121 +++++++++++++++++++++++++++++
fs/nilfs2/sysfs.h | 59 ++++++++++++++
3 files changed, 196 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-fs-nilfs2
create mode 100644 fs/nilfs2/sysfs.c
create mode 100644 fs/nilfs2/sysfs.h

diff --git a/Documentation/ABI/testing/sysfs-fs-nilfs2 b/Documentation/ABI/testing/sysfs-fs-nilfs2
new file mode 100644
index 0000000..2e2a6df
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-fs-nilfs2
@@ -0,0 +1,16 @@
+
+What: /sys/fs/nilfs2/features/revision
+Date: April 2014
+KernelVersion: 3.15
+Contact: "Vyacheslav Dubeyko" <slava-***@public.gmane.org>
+Description:
+ Show current revision of NILFS file system driver.
+ This value informs about file system revision that
+ driver is ready to support.
+
+What: /sys/fs/nilfs2/features/README
+Date: April 2014
+KernelVersion: 3.15
+Contact: "Vyacheslav Dubeyko" <slava-***@public.gmane.org>
+Description:
+ Describe attributes of /sys/fs/nilfs2/features group.
diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c
new file mode 100644
index 0000000..8d025b7
--- /dev/null
+++ b/fs/nilfs2/sysfs.c
@@ -0,0 +1,121 @@
+/*
+ * sysfs.c - sysfs support implementation.
+ *
+ * Copyright (C) 2005-2014 Nippon Telegraph and Telephone Corporation.
+ * Copyright (C) 2014 HGST, Inc., a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Written by Vyacheslav Dubeyko <Vyacheslav.Dubeyko-***@public.gmane.org>
+ */
+
+#include <linux/kobject.h>
+
+#include "nilfs.h"
+#include "mdt.h"
+#include "sufile.h"
+#include "cpfile.h"
+#include "sysfs.h"
+
+/* /sys/fs/<nilfs>/ */
+static struct kset *nilfs_kset;
+
+#define NILFS_SHOW_TIME(time_t_val, buf) ({ \
+ struct tm res; \
+ int count = 0; \
+ time_to_tm(time_t_val, 0, &res); \
+ res.tm_year += 1900; \
+ res.tm_mon += 1; \
+ count = scnprintf(buf, PAGE_SIZE, \
+ "%ld-%.2d-%.2d %.2d:%.2d:%.2d\n", \
+ res.tm_year, res.tm_mon, res.tm_mday, \
+ res.tm_hour, res.tm_min, res.tm_sec);\
+ count; \
+})
+
+/************************************************************************
+ * NILFS feature attrs *
+ ************************************************************************/
+
+static ssize_t nilfs_feature_revision_show(struct kobject *kobj,
+ struct attribute *attr, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, "%d.%d\n",
+ NILFS_CURRENT_REV, NILFS_MINOR_REV);
+}
+
+static const char features_readme_str[] =
+ "The features group contains attributes that describe NILFS file\n"
+ "system driver features.\n\n"
+ "(1) revision\n\tshow current revision of NILFS file system driver.\n";
+
+static ssize_t nilfs_feature_README_show(struct kobject *kobj,
+ struct attribute *attr,
+ char *buf)
+{
+ return snprintf(buf, PAGE_SIZE, features_readme_str);
+}
+
+NILFS_FEATURE_RO_ATTR(revision);
+NILFS_FEATURE_RO_ATTR(README);
+
+static struct attribute *nilfs_feature_attrs[] = {
+ NILFS_FEATURE_ATTR_LIST(revision),
+ NILFS_FEATURE_ATTR_LIST(README),
+ NULL,
+};
+
+static const struct attribute_group nilfs_feature_attr_group = {
+ .name = "features",
+ .attrs = nilfs_feature_attrs,
+};
+
+int __init nilfs_sysfs_init(void)
+{
+ char *name = "nilfs\0\0";
+ int len;
+ int err;
+
+ len = snprintf(name + strlen(name), 2, "%d", NILFS_CURRENT_REV);
+ if (len != 1) {
+ err = -EINVAL;
+ goto failed_sysfs_init;
+ }
+
+ nilfs_kset = kset_create_and_add(name, NULL, fs_kobj);
+ if (!nilfs_kset) {
+ err = -ENOMEM;
+ printk(KERN_ERR "NILFS: unable to create sysfs entry: err %d\n",
+ err);
+ goto failed_sysfs_init;
+ }
+
+ err = sysfs_create_group(&nilfs_kset->kobj, &nilfs_feature_attr_group);
+ if (unlikely(err)) {
+ printk(KERN_ERR "NILFS: unable to create feature group: err %d\n",
+ err);
+ goto cleanup_sysfs_init;
+ }
+
+ return 0;
+
+cleanup_sysfs_init:
+ kset_unregister(nilfs_kset);
+
+failed_sysfs_init:
+ return err;
+}
+
+void nilfs_sysfs_exit(void)
+{
+ sysfs_remove_group(&nilfs_kset->kobj, &nilfs_feature_attr_group);
+ kset_unregister(nilfs_kset);
+}
diff --git a/fs/nilfs2/sysfs.h b/fs/nilfs2/sysfs.h
new file mode 100644
index 0000000..b3ba2e4
--- /dev/null
+++ b/fs/nilfs2/sysfs.h
@@ -0,0 +1,59 @@
+/*
+ * sysfs.h - sysfs support declarations.
+ *
+ * Copyright (C) 2005-2014 Nippon Telegraph and Telephone Corporation.
+ * Copyright (C) 2014 HGST, Inc., a Western Digital Company.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Written by Vyacheslav Dubeyko <Vyacheslav.Dubeyko-***@public.gmane.org>
+ */
+
+#ifndef _NILFS_SYSFS_H
+#define _NILFS_SYSFS_H
+
+#include <linux/sysfs.h>
+
+#define NILFS_COMMON_ATTR_STRUCT(name) \
+struct nilfs_##name##_attr { \
+ struct attribute attr; \
+ ssize_t (*show)(struct kobject *, struct attribute *, \
+ char *); \
+ ssize_t (*store)(struct kobject *, struct attribute *, \
+ const char *, size_t); \
+};
+
+NILFS_COMMON_ATTR_STRUCT(feature);
+
+#define NILFS_ATTR(type, name, mode, show, store) \
+ static struct nilfs_##type##_attr nilfs_##type##_attr_##name = \
+ __ATTR(name, mode, show, store)
+
+#define NILFS_INFO_ATTR(type, name) \
+ NILFS_ATTR(type, name, 0444, NULL, NULL)
+#define NILFS_RO_ATTR(type, name) \
+ NILFS_ATTR(type, name, 0444, nilfs_##type##_##name##_show, NULL)
+#define NILFS_RW_ATTR(type, name) \
+ NILFS_ATTR(type, name, 0644, \
+ nilfs_##type##_##name##_show, \
+ nilfs_##type##_##name##_store)
+
+#define NILFS_FEATURE_INFO_ATTR(name) \
+ NILFS_INFO_ATTR(feature, name)
+#define NILFS_FEATURE_RO_ATTR(name) \
+ NILFS_RO_ATTR(feature, name)
+#define NILFS_FEATURE_RW_ATTR(name) \
+ NILFS_RW_ATTR(feature, name)
+
+#define NILFS_FEATURE_ATTR_LIST(name) \
+ (&nilfs_feature_attr_##name.attr)
+
+#endif /* _NILFS_SYSFS_H */