text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * sysfs.c - sysfs support implementation.
   *
   * Copyright (C) 2005-2014 Nippon Telegraph and Telephone Corporation.
   * Copyright (C) 2014 HGST, Inc., a Western Digital Company.
   *
   * Written by Vyacheslav Dubeyko <Vyacheslav.Dubeyko@hgst.com>
   */
  
  #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; \
  		time64_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; \
  })
  
  #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) \
  static 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; \
  } \
  static void nilfs_sysfs_delete_##name##_group(struct the_nilfs *nilfs) \
  { \
  	kobject_del(&nilfs->ns_##parent_name##_subgroups->sg_##name##_kobj); \
  }
  
  /************************************************************************
   *                        NILFS snapshot attrs                          *
   ************************************************************************/
  
  static ssize_t
  nilfs_snapshot_inodes_count_show(struct nilfs_snapshot_attr *attr,
  				 struct nilfs_root *root, char *buf)
  {
  	return snprintf(buf, PAGE_SIZE, "%llu\n",
  			(unsigned long long)atomic64_read(&root->inodes_count));
  }
  
  static ssize_t
  nilfs_snapshot_blocks_count_show(struct nilfs_snapshot_attr *attr,
  				 struct nilfs_root *root, char *buf)
  {
  	return snprintf(buf, PAGE_SIZE, "%llu\n",
  			(unsigned long long)atomic64_read(&root->blocks_count));
  }
  
  static const char snapshot_readme_str[] =
  	"The group contains details about mounted snapshot.\n\n"
  	"(1) inodes_count\n\tshow number of inodes for snapshot.\n\n"
  	"(2) blocks_count\n\tshow number of blocks for snapshot.\n\n";
  
  static ssize_t
  nilfs_snapshot_README_show(struct nilfs_snapshot_attr *attr,
  			    struct nilfs_root *root, char *buf)
  {
  	return snprintf(buf, PAGE_SIZE, snapshot_readme_str);
  }
  
  NILFS_SNAPSHOT_RO_ATTR(inodes_count);
  NILFS_SNAPSHOT_RO_ATTR(blocks_count);
  NILFS_SNAPSHOT_RO_ATTR(README);
  
  static struct attribute *nilfs_snapshot_attrs[] = {
  	NILFS_SNAPSHOT_ATTR_LIST(inodes_count),
  	NILFS_SNAPSHOT_ATTR_LIST(blocks_count),
  	NILFS_SNAPSHOT_ATTR_LIST(README),
  	NULL,
  };
  
  static ssize_t nilfs_snapshot_attr_show(struct kobject *kobj,
  					struct attribute *attr, char *buf)
  {
  	struct nilfs_root *root =
  			container_of(kobj, struct nilfs_root, snapshot_kobj);
  	struct nilfs_snapshot_attr *a =
  			container_of(attr, struct nilfs_snapshot_attr, attr);
  
  	return a->show ? a->show(a, root, buf) : 0;
  }
  
  static ssize_t nilfs_snapshot_attr_store(struct kobject *kobj,
  					 struct attribute *attr,
  					 const char *buf, size_t len)
  {
  	struct nilfs_root *root =
  			container_of(kobj, struct nilfs_root, snapshot_kobj);
  	struct nilfs_snapshot_attr *a =
  			container_of(attr, struct nilfs_snapshot_attr, attr);
  
  	return a->store ? a->store(a, root, buf, len) : 0;
  }
  
  static void nilfs_snapshot_attr_release(struct kobject *kobj)
  {
  	struct nilfs_root *root = container_of(kobj, struct nilfs_root,
  						snapshot_kobj);
  	complete(&root->snapshot_kobj_unregister);
  }
  
  static const struct sysfs_ops nilfs_snapshot_attr_ops = {
  	.show	= nilfs_snapshot_attr_show,
  	.store	= nilfs_snapshot_attr_store,
  };
  
  static struct kobj_type nilfs_snapshot_ktype = {
  	.default_attrs	= nilfs_snapshot_attrs,
  	.sysfs_ops	= &nilfs_snapshot_attr_ops,
  	.release	= nilfs_snapshot_attr_release,
  };
  
  int nilfs_sysfs_create_snapshot_group(struct nilfs_root *root)
  {
  	struct the_nilfs *nilfs;
  	struct kobject *parent;
  	int err;
  
  	nilfs = root->nilfs;
  	parent = &nilfs->ns_dev_subgroups->sg_mounted_snapshots_kobj;
  	root->snapshot_kobj.kset = nilfs_kset;
  	init_completion(&root->snapshot_kobj_unregister);
  
  	if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
  		err = kobject_init_and_add(&root->snapshot_kobj,
  					    &nilfs_snapshot_ktype,
  					    &nilfs->ns_dev_kobj,
  					    "current_checkpoint");
  	} else {
  		err = kobject_init_and_add(&root->snapshot_kobj,
  					    &nilfs_snapshot_ktype,
  					    parent,
  					    "%llu", root->cno);
  	}
  
  	if (err)
  		return err;
  
  	return 0;
  }
  
  void nilfs_sysfs_delete_snapshot_group(struct nilfs_root *root)
  {
  	kobject_del(&root->snapshot_kobj);
  }
  
  /************************************************************************
   *                    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                         *
   ************************************************************************/
  
  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) {
  		nilfs_err(nilfs->ns_sb, "unable to get checkpoint stat: err=%d",
  			  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) {
  		nilfs_err(nilfs->ns_sb, "unable to get checkpoint stat: err=%d",
  			  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_segctor_sem);
  	cno = nilfs->ns_cno;
  	up_read(&nilfs->ns_segctor_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                          *
   ************************************************************************/
  
  static ssize_t
  nilfs_segments_segments_number_show(struct nilfs_segments_attr *attr,
  				     struct the_nilfs *nilfs,
  				     char *buf)
  {
  	return snprintf(buf, PAGE_SIZE, "%lu\n", nilfs->ns_nsegments);
  }
  
  static ssize_t
  nilfs_segments_blocks_per_segment_show(struct nilfs_segments_attr *attr,
  					struct the_nilfs *nilfs,
  					char *buf)
  {
  	return snprintf(buf, PAGE_SIZE, "%lu\n", nilfs->ns_blocks_per_segment);
  }
  
  static ssize_t
  nilfs_segments_clean_segments_show(struct nilfs_segments_attr *attr,
  				    struct the_nilfs *nilfs,
  				    char *buf)
  {
  	unsigned long ncleansegs;
  
  	down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
  	ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
  	up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%lu\n", ncleansegs);
  }
  
  static ssize_t
  nilfs_segments_dirty_segments_show(struct nilfs_segments_attr *attr,
  				    struct the_nilfs *nilfs,
  				    char *buf)
  {
  	struct nilfs_sustat sustat;
  	int err;
  
  	down_read(&nilfs->ns_segctor_sem);
  	err = nilfs_sufile_get_stat(nilfs->ns_sufile, &sustat);
  	up_read(&nilfs->ns_segctor_sem);
  	if (err < 0) {
  		nilfs_err(nilfs->ns_sb, "unable to get segment stat: err=%d",
  			  err);
  		return err;
  	}
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", sustat.ss_ndirtysegs);
  }
  
  static const char segments_readme_str[] =
  	"The segments group contains attributes that describe\n"
  	"details about volume's segments.\n\n"
  	"(1) segments_number\n\tshow number of segments on volume.\n\n"
  	"(2) blocks_per_segment\n\tshow number of blocks in segment.\n\n"
  	"(3) clean_segments\n\tshow count of clean segments.\n\n"
  	"(4) dirty_segments\n\tshow count of dirty segments.\n\n";
  
  static ssize_t
  nilfs_segments_README_show(struct nilfs_segments_attr *attr,
  			    struct the_nilfs *nilfs,
  			    char *buf)
  {
  	return snprintf(buf, PAGE_SIZE, segments_readme_str);
  }
  
  NILFS_SEGMENTS_RO_ATTR(segments_number);
  NILFS_SEGMENTS_RO_ATTR(blocks_per_segment);
  NILFS_SEGMENTS_RO_ATTR(clean_segments);
  NILFS_SEGMENTS_RO_ATTR(dirty_segments);
  NILFS_SEGMENTS_RO_ATTR(README);
  
  static struct attribute *nilfs_segments_attrs[] = {
  	NILFS_SEGMENTS_ATTR_LIST(segments_number),
  	NILFS_SEGMENTS_ATTR_LIST(blocks_per_segment),
  	NILFS_SEGMENTS_ATTR_LIST(clean_segments),
  	NILFS_SEGMENTS_ATTR_LIST(dirty_segments),
  	NILFS_SEGMENTS_ATTR_LIST(README),
  	NULL,
  };
  
  NILFS_DEV_INT_GROUP_OPS(segments, dev);
  NILFS_DEV_INT_GROUP_TYPE(segments, dev);
  NILFS_DEV_INT_GROUP_FNS(segments, dev);
  
  /************************************************************************
   *                        NILFS segctor attrs                           *
   ************************************************************************/
  
  static ssize_t
  nilfs_segctor_last_pseg_block_show(struct nilfs_segctor_attr *attr,
  				    struct the_nilfs *nilfs,
  				    char *buf)
  {
  	sector_t last_pseg;
  
  	spin_lock(&nilfs->ns_last_segment_lock);
  	last_pseg = nilfs->ns_last_pseg;
  	spin_unlock(&nilfs->ns_last_segment_lock);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n",
  			(unsigned long long)last_pseg);
  }
  
  static ssize_t
  nilfs_segctor_last_seg_sequence_show(struct nilfs_segctor_attr *attr,
  					struct the_nilfs *nilfs,
  					char *buf)
  {
  	u64 last_seq;
  
  	spin_lock(&nilfs->ns_last_segment_lock);
  	last_seq = nilfs->ns_last_seq;
  	spin_unlock(&nilfs->ns_last_segment_lock);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", last_seq);
  }
  
  static ssize_t
  nilfs_segctor_last_seg_checkpoint_show(struct nilfs_segctor_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_segctor_current_seg_sequence_show(struct nilfs_segctor_attr *attr,
  					struct the_nilfs *nilfs,
  					char *buf)
  {
  	u64 seg_seq;
  
  	down_read(&nilfs->ns_segctor_sem);
  	seg_seq = nilfs->ns_seg_seq;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", seg_seq);
  }
  
  static ssize_t
  nilfs_segctor_current_last_full_seg_show(struct nilfs_segctor_attr *attr,
  					 struct the_nilfs *nilfs,
  					 char *buf)
  {
  	__u64 segnum;
  
  	down_read(&nilfs->ns_segctor_sem);
  	segnum = nilfs->ns_segnum;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", segnum);
  }
  
  static ssize_t
  nilfs_segctor_next_full_seg_show(struct nilfs_segctor_attr *attr,
  				 struct the_nilfs *nilfs,
  				 char *buf)
  {
  	__u64 nextnum;
  
  	down_read(&nilfs->ns_segctor_sem);
  	nextnum = nilfs->ns_nextnum;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", nextnum);
  }
  
  static ssize_t
  nilfs_segctor_next_pseg_offset_show(struct nilfs_segctor_attr *attr,
  					struct the_nilfs *nilfs,
  					char *buf)
  {
  	unsigned long pseg_offset;
  
  	down_read(&nilfs->ns_segctor_sem);
  	pseg_offset = nilfs->ns_pseg_offset;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%lu\n", pseg_offset);
  }
  
  static ssize_t
  nilfs_segctor_next_checkpoint_show(struct nilfs_segctor_attr *attr,
  					struct the_nilfs *nilfs,
  					char *buf)
  {
  	__u64 cno;
  
  	down_read(&nilfs->ns_segctor_sem);
  	cno = nilfs->ns_cno;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", cno);
  }
  
  static ssize_t
  nilfs_segctor_last_seg_write_time_show(struct nilfs_segctor_attr *attr,
  					struct the_nilfs *nilfs,
  					char *buf)
  {
  	time64_t ctime;
  
  	down_read(&nilfs->ns_segctor_sem);
  	ctime = nilfs->ns_ctime;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return NILFS_SHOW_TIME(ctime, buf);
  }
  
  static ssize_t
  nilfs_segctor_last_seg_write_time_secs_show(struct nilfs_segctor_attr *attr,
  					    struct the_nilfs *nilfs,
  					    char *buf)
  {
  	time64_t ctime;
  
  	down_read(&nilfs->ns_segctor_sem);
  	ctime = nilfs->ns_ctime;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", ctime);
  }
  
  static ssize_t
  nilfs_segctor_last_nongc_write_time_show(struct nilfs_segctor_attr *attr,
  					 struct the_nilfs *nilfs,
  					 char *buf)
  {
  	time64_t nongc_ctime;
  
  	down_read(&nilfs->ns_segctor_sem);
  	nongc_ctime = nilfs->ns_nongc_ctime;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return NILFS_SHOW_TIME(nongc_ctime, buf);
  }
  
  static ssize_t
  nilfs_segctor_last_nongc_write_time_secs_show(struct nilfs_segctor_attr *attr,
  						struct the_nilfs *nilfs,
  						char *buf)
  {
  	time64_t nongc_ctime;
  
  	down_read(&nilfs->ns_segctor_sem);
  	nongc_ctime = nilfs->ns_nongc_ctime;
  	up_read(&nilfs->ns_segctor_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", nongc_ctime);
  }
  
  static ssize_t
  nilfs_segctor_dirty_data_blocks_count_show(struct nilfs_segctor_attr *attr,
  					    struct the_nilfs *nilfs,
  					    char *buf)
  {
  	u32 ndirtyblks;
  
  	down_read(&nilfs->ns_segctor_sem);
  	ndirtyblks = atomic_read(&nilfs->ns_ndirtyblks);
  	up_read(&nilfs->ns_segctor_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%u\n", ndirtyblks);
  }
  
  static const char segctor_readme_str[] =
  	"The segctor group contains attributes that describe\n"
  	"segctor thread activity details.\n\n"
  	"(1) last_pseg_block\n"
  	"\tshow start block number of the latest segment.\n\n"
  	"(2) last_seg_sequence\n"
  	"\tshow sequence value of the latest segment.\n\n"
  	"(3) last_seg_checkpoint\n"
  	"\tshow checkpoint number of the latest segment.\n\n"
  	"(4) current_seg_sequence\n\tshow segment sequence counter.\n\n"
  	"(5) current_last_full_seg\n"
  	"\tshow index number of the latest full segment.\n\n"
  	"(6) next_full_seg\n"
  	"\tshow index number of the full segment index to be used next.\n\n"
  	"(7) next_pseg_offset\n"
  	"\tshow offset of next partial segment in the current full segment.\n\n"
  	"(8) next_checkpoint\n\tshow next checkpoint number.\n\n"
  	"(9) last_seg_write_time\n"
  	"\tshow write time of the last segment in human-readable format.\n\n"
  	"(10) last_seg_write_time_secs\n"
  	"\tshow write time of the last segment in seconds.\n\n"
  	"(11) last_nongc_write_time\n"
  	"\tshow write time of the last segment not for cleaner operation "
  	"in human-readable format.\n\n"
  	"(12) last_nongc_write_time_secs\n"
  	"\tshow write time of the last segment not for cleaner operation "
  	"in seconds.\n\n"
  	"(13) dirty_data_blocks_count\n"
  	"\tshow number of dirty data blocks.\n\n";
  
  static ssize_t
  nilfs_segctor_README_show(struct nilfs_segctor_attr *attr,
  			  struct the_nilfs *nilfs, char *buf)
  {
  	return snprintf(buf, PAGE_SIZE, segctor_readme_str);
  }
  
  NILFS_SEGCTOR_RO_ATTR(last_pseg_block);
  NILFS_SEGCTOR_RO_ATTR(last_seg_sequence);
  NILFS_SEGCTOR_RO_ATTR(last_seg_checkpoint);
  NILFS_SEGCTOR_RO_ATTR(current_seg_sequence);
  NILFS_SEGCTOR_RO_ATTR(current_last_full_seg);
  NILFS_SEGCTOR_RO_ATTR(next_full_seg);
  NILFS_SEGCTOR_RO_ATTR(next_pseg_offset);
  NILFS_SEGCTOR_RO_ATTR(next_checkpoint);
  NILFS_SEGCTOR_RO_ATTR(last_seg_write_time);
  NILFS_SEGCTOR_RO_ATTR(last_seg_write_time_secs);
  NILFS_SEGCTOR_RO_ATTR(last_nongc_write_time);
  NILFS_SEGCTOR_RO_ATTR(last_nongc_write_time_secs);
  NILFS_SEGCTOR_RO_ATTR(dirty_data_blocks_count);
  NILFS_SEGCTOR_RO_ATTR(README);
  
  static struct attribute *nilfs_segctor_attrs[] = {
  	NILFS_SEGCTOR_ATTR_LIST(last_pseg_block),
  	NILFS_SEGCTOR_ATTR_LIST(last_seg_sequence),
  	NILFS_SEGCTOR_ATTR_LIST(last_seg_checkpoint),
  	NILFS_SEGCTOR_ATTR_LIST(current_seg_sequence),
  	NILFS_SEGCTOR_ATTR_LIST(current_last_full_seg),
  	NILFS_SEGCTOR_ATTR_LIST(next_full_seg),
  	NILFS_SEGCTOR_ATTR_LIST(next_pseg_offset),
  	NILFS_SEGCTOR_ATTR_LIST(next_checkpoint),
  	NILFS_SEGCTOR_ATTR_LIST(last_seg_write_time),
  	NILFS_SEGCTOR_ATTR_LIST(last_seg_write_time_secs),
  	NILFS_SEGCTOR_ATTR_LIST(last_nongc_write_time),
  	NILFS_SEGCTOR_ATTR_LIST(last_nongc_write_time_secs),
  	NILFS_SEGCTOR_ATTR_LIST(dirty_data_blocks_count),
  	NILFS_SEGCTOR_ATTR_LIST(README),
  	NULL,
  };
  
  NILFS_DEV_INT_GROUP_OPS(segctor, dev);
  NILFS_DEV_INT_GROUP_TYPE(segctor, dev);
  NILFS_DEV_INT_GROUP_FNS(segctor, dev);
  
  /************************************************************************
   *                        NILFS superblock attrs                        *
   ************************************************************************/
  
  static ssize_t
  nilfs_superblock_sb_write_time_show(struct nilfs_superblock_attr *attr,
  				     struct the_nilfs *nilfs,
  				     char *buf)
  {
  	time64_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)
  {
  	time64_t sbwtime;
  
  	down_read(&nilfs->ns_sem);
  	sbwtime = nilfs->ns_sbwtime;
  	up_read(&nilfs->ns_sem);
  
  	return snprintf(buf, PAGE_SIZE, "%llu\n", sbwtime);
  }
  
  static ssize_t
  nilfs_superblock_sb_write_count_show(struct nilfs_superblock_attr *attr,
  				      struct the_nilfs *nilfs,
  				      char *buf)
  {
  	unsigned int 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 int 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 int val;
  	int err;
  
  	err = kstrtouint(skip_spaces(buf), 0, &val);
  	if (err) {
  		nilfs_err(nilfs->ns_sb, "unable to convert string: err=%d",
  			  err);
  		return err;
  	}
  
  	if (val < NILFS_SB_FREQ) {
  		val = NILFS_SB_FREQ;
  		nilfs_warn(nilfs->ns_sb,
  			   "superblock update frequency cannot be lesser than 10 seconds");
  	}
  
  	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                            *
   ************************************************************************/
  
  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;
  	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;
  		nilfs_err(sb, "unable to allocate memory for device group");
  		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 free_dev_subgroups;
  
  	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;
  
  	err = nilfs_sysfs_create_superblock_group(nilfs);
  	if (err)
  		goto delete_segments_group;
  
  	err = nilfs_sysfs_create_segctor_group(nilfs);
  	if (err)
  		goto delete_superblock_group;
  
  	return 0;
  
  delete_superblock_group:
  	nilfs_sysfs_delete_superblock_group(nilfs);
  
  delete_segments_group:
  	nilfs_sysfs_delete_segments_group(nilfs);
  
  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);
  
  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_mounted_snapshots_group(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);
  	kobject_del(&nilfs->ns_dev_kobj);
  	kfree(nilfs->ns_dev_subgroups);
  }
  
  /************************************************************************
   *                        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)
  {
  	int err;
  
  	nilfs_kset = kset_create_and_add(NILFS_ROOT_GROUP_NAME, NULL, fs_kobj);
  	if (!nilfs_kset) {
  		err = -ENOMEM;
  		nilfs_err(NULL, "unable to create sysfs entry: err=%d", err);
  		goto failed_sysfs_init;
  	}
  
  	err = sysfs_create_group(&nilfs_kset->kobj, &nilfs_feature_attr_group);
  	if (unlikely(err)) {
  		nilfs_err(NULL, "unable to create feature group: err=%d", 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);
  }
  