fs/ext4/sysfs.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  *  linux/fs/ext4/sysfs.c
  *
  * Copyright (C) 1992, 1993, 1994, 1995
  * Remy Card (card@masi.ibp.fr)
  * Theodore Ts'o (tytso@mit.edu)
  *
  */

 #include <linux/time.h>
 #include <linux/fs.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/proc_fs.h>

 #include "ext4.h"
 #include "ext4_jbd2.h"

 typedef enum {
 	attr_noop,
 	attr_delayed_allocation_blocks,
 	attr_session_write_kbytes,
 	attr_lifetime_write_kbytes,
 	attr_reserved_clusters,
 	attr_inode_readahead,
 	attr_trigger_test_error,
 	attr_first_error_time,
 	attr_last_error_time,
 	attr_feature,
 	attr_pointer_ui,
 	attr_pointer_atomic,
 	attr_journal_task,
 } attr_id_t;

 typedef enum {
 	ptr_explicit,
 	ptr_ext4_sb_info_offset,
 	ptr_ext4_super_block_offset,
 } attr_ptr_t;

 static const char proc_dirname[] = "fs/ext4";
 static struct proc_dir_entry *ext4_proc_root;

 struct ext4_attr {
 	struct attribute attr;
 	short attr_id;
 	short attr_ptr;
 	union {
 		int offset;
 		void *explicit_ptr;
 	} u;
 };

 static ssize_t session_write_kbytes_show(struct ext4_sb_info *sbi, char *buf)
 {
 	struct super_block *sb = sbi->s_buddy_cache->i_sb;

 	if (!sb->s_bdev->bd_part)
 		return snprintf(buf, PAGE_SIZE, "0\n");
 	return snprintf(buf, PAGE_SIZE, "%lu\n",
 			(part_stat_read(sb->s_bdev->bd_part,
 					sectors[STAT_WRITE]) -
 			 sbi->s_sectors_written_start) >> 1);
 }

 static ssize_t lifetime_write_kbytes_show(struct ext4_sb_info *sbi, char *buf)
 {
 	struct super_block *sb = sbi->s_buddy_cache->i_sb;

 	if (!sb->s_bdev->bd_part)
 		return snprintf(buf, PAGE_SIZE, "0\n");
 	return snprintf(buf, PAGE_SIZE, "%llu\n",
 			(unsigned long long)(sbi->s_kbytes_written +
 			((part_stat_read(sb->s_bdev->bd_part,
 					 sectors[STAT_WRITE]) -
 			  EXT4_SB(sb)->s_sectors_written_start) >> 1)));
 }

 static ssize_t inode_readahead_blks_store(struct ext4_sb_info *sbi,
 					  const char *buf, size_t count)
 {
 	unsigned long t;
 	int ret;

 	ret = kstrtoul(skip_spaces(buf), 0, &t);
 	if (ret)
 		return ret;

 	if (t && (!is_power_of_2(t) || t > 0x40000000))
 		return -EINVAL;

 	sbi->s_inode_readahead_blks = t;
 	return count;
 }

 static ssize_t reserved_clusters_store(struct ext4_sb_info *sbi,
 				   const char *buf, size_t count)
 {
 	unsigned long long val;
 	ext4_fsblk_t clusters = (ext4_blocks_count(sbi->s_es) >>
 				 sbi->s_cluster_bits);
 	int ret;

 	ret = kstrtoull(skip_spaces(buf), 0, &val);
 	if (ret || val >= clusters)
 		return -EINVAL;

 	atomic64_set(&sbi->s_resv_clusters, val);
 	return count;
 }

 static ssize_t trigger_test_error(struct ext4_sb_info *sbi,
 				  const char *buf, size_t count)
 {
 	int len = count;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;

 	if (len && buf[len-1] == '\n')
 		len--;

 	if (len)
 		ext4_error(sbi->s_sb, "%.*s", len, buf);
 	return count;
 }

 static ssize_t journal_task_show(struct ext4_sb_info *sbi, char *buf)
 {
 	if (!sbi->s_journal)
 		return snprintf(buf, PAGE_SIZE, "<none>\n");
 	return snprintf(buf, PAGE_SIZE, "%d\n",
 			task_pid_vnr(sbi->s_journal->j_task));
 }

 #define EXT4_ATTR(_name,_mode,_id)					\
 static struct ext4_attr ext4_attr_##_name = {				\
 	.attr = {.name = __stringify(_name), .mode = _mode },		\
 	.attr_id = attr_##_id,						\
 }

 #define EXT4_ATTR_FUNC(_name,_mode)  EXT4_ATTR(_name,_mode,_name)

 #define EXT4_ATTR_FEATURE(_name)   EXT4_ATTR(_name, 0444, feature)

 #define EXT4_ATTR_OFFSET(_name,_mode,_id,_struct,_elname)	\
 static struct ext4_attr ext4_attr_##_name = {			\
 	.attr = {.name = __stringify(_name), .mode = _mode },	\
 	.attr_id = attr_##_id,					\
 	.attr_ptr = ptr_##_struct##_offset,			\
 	.u = {							\
 		.offset = offsetof(struct _struct, _elname),\
 	},							\
 }

 #define EXT4_RO_ATTR_ES_UI(_name,_elname)				\
 	EXT4_ATTR_OFFSET(_name, 0444, pointer_ui, ext4_super_block, _elname)

 #define EXT4_RW_ATTR_SBI_UI(_name,_elname)	\
 	EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname)

 #define EXT4_ATTR_PTR(_name,_mode,_id,_ptr) \
 static struct ext4_attr ext4_attr_##_name = {			\
 	.attr = {.name = __stringify(_name), .mode = _mode },	\
 	.attr_id = attr_##_id,					\
 	.attr_ptr = ptr_explicit,				\
 	.u = {							\
 		.explicit_ptr = _ptr,				\
 	},							\
 }

 #define ATTR_LIST(name) &ext4_attr_##name.attr

 EXT4_ATTR_FUNC(delayed_allocation_blocks, 0444);
 EXT4_ATTR_FUNC(session_write_kbytes, 0444);
 EXT4_ATTR_FUNC(lifetime_write_kbytes, 0444);
 EXT4_ATTR_FUNC(reserved_clusters, 0644);

 EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
 		 ext4_sb_info, s_inode_readahead_blks);
 EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
 EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
 EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
 EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
 EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
 EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
 EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
 EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
 EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
 EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
 EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
 EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
 EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
 EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
 EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
 EXT4_RO_ATTR_ES_UI(errors_count, s_error_count);
 EXT4_ATTR(first_error_time, 0444, first_error_time);
 EXT4_ATTR(last_error_time, 0444, last_error_time);
 EXT4_ATTR(journal_task, 0444, journal_task);

 static unsigned int old_bump_val = 128;
 EXT4_ATTR_PTR(max_writeback_mb_bump, 0444, pointer_ui, &old_bump_val);

 static struct attribute *ext4_attrs[] = {
 	ATTR_LIST(delayed_allocation_blocks),
 	ATTR_LIST(session_write_kbytes),
 	ATTR_LIST(lifetime_write_kbytes),
 	ATTR_LIST(reserved_clusters),
 	ATTR_LIST(inode_readahead_blks),
 	ATTR_LIST(inode_goal),
 	ATTR_LIST(mb_stats),
 	ATTR_LIST(mb_max_to_scan),
 	ATTR_LIST(mb_min_to_scan),
 	ATTR_LIST(mb_order2_req),
 	ATTR_LIST(mb_stream_req),
 	ATTR_LIST(mb_group_prealloc),
 	ATTR_LIST(max_writeback_mb_bump),
 	ATTR_LIST(extent_max_zeroout_kb),
 	ATTR_LIST(trigger_fs_error),
 	ATTR_LIST(err_ratelimit_interval_ms),
 	ATTR_LIST(err_ratelimit_burst),
 	ATTR_LIST(warning_ratelimit_interval_ms),
 	ATTR_LIST(warning_ratelimit_burst),
 	ATTR_LIST(msg_ratelimit_interval_ms),
 	ATTR_LIST(msg_ratelimit_burst),
 	ATTR_LIST(errors_count),
 	ATTR_LIST(first_error_time),
 	ATTR_LIST(last_error_time),
 	ATTR_LIST(journal_task),
 	NULL,
 };

 /* Features this copy of ext4 supports */
 EXT4_ATTR_FEATURE(lazy_itable_init);
 EXT4_ATTR_FEATURE(batched_discard);
 EXT4_ATTR_FEATURE(meta_bg_resize);
 #ifdef CONFIG_FS_ENCRYPTION
 EXT4_ATTR_FEATURE(encryption);
 #endif
 EXT4_ATTR_FEATURE(metadata_csum_seed);

 static struct attribute *ext4_feat_attrs[] = {
 	ATTR_LIST(lazy_itable_init),
 	ATTR_LIST(batched_discard),
 	ATTR_LIST(meta_bg_resize),
 #ifdef CONFIG_FS_ENCRYPTION
 	ATTR_LIST(encryption),
 #endif
 	ATTR_LIST(metadata_csum_seed),
 	NULL,
 };

 static void *calc_ptr(struct ext4_attr *a, struct ext4_sb_info *sbi)
 {
 	switch (a->attr_ptr) {
 	case ptr_explicit:
 		return a->u.explicit_ptr;
 	case ptr_ext4_sb_info_offset:
 		return (void *) (((char *) sbi) + a->u.offset);
 	case ptr_ext4_super_block_offset:
 		return (void *) (((char *) sbi->s_es) + a->u.offset);
 	}
 	return NULL;
 }

 static ssize_t __print_tstamp(char *buf, __le32 lo, __u8 hi)
 {
 	return snprintf(buf, PAGE_SIZE, "%lld",
 			((time64_t)hi << 32) + le32_to_cpu(lo));
 }

 #define print_tstamp(buf, es, tstamp) \
 	__print_tstamp(buf, (es)->tstamp, (es)->tstamp ## _hi)

 static ssize_t ext4_attr_show(struct kobject *kobj,
 			      struct attribute *attr, char *buf)
 {
 	struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
 						s_kobj);
 	struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
 	void *ptr = calc_ptr(a, sbi);

 	switch (a->attr_id) {
 	case attr_delayed_allocation_blocks:
 		return snprintf(buf, PAGE_SIZE, "%llu\n",
 				(s64) EXT4_C2B(sbi,
 		       percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
 	case attr_session_write_kbytes:
 		return session_write_kbytes_show(sbi, buf);
 	case attr_lifetime_write_kbytes:
 		return lifetime_write_kbytes_show(sbi, buf);
 	case attr_reserved_clusters:
 		return snprintf(buf, PAGE_SIZE, "%llu\n",
 				(unsigned long long)
 				atomic64_read(&sbi->s_resv_clusters));
 	case attr_inode_readahead:
 	case attr_pointer_ui:
 		if (!ptr)
 			return 0;
 		if (a->attr_ptr == ptr_ext4_super_block_offset)
 			return snprintf(buf, PAGE_SIZE, "%u\n",
 					le32_to_cpup(ptr));
 		else
 			return snprintf(buf, PAGE_SIZE, "%u\n",
 					*((unsigned int *) ptr));
 	case attr_pointer_atomic:
 		if (!ptr)
 			return 0;
 		return snprintf(buf, PAGE_SIZE, "%d\n",
 				atomic_read((atomic_t *) ptr));
 	case attr_feature:
 		return snprintf(buf, PAGE_SIZE, "supported\n");
 	case attr_first_error_time:
 		return print_tstamp(buf, sbi->s_es, s_first_error_time);
 	case attr_last_error_time:
 		return print_tstamp(buf, sbi->s_es, s_last_error_time);
 	case attr_journal_task:
 		return journal_task_show(sbi, buf);
 	}

 	return 0;
 }

 static ssize_t ext4_attr_store(struct kobject *kobj,
 			       struct attribute *attr,
 			       const char *buf, size_t len)
 {
 	struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
 						s_kobj);
 	struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
 	void *ptr = calc_ptr(a, sbi);
 	unsigned long t;
 	int ret;

 	switch (a->attr_id) {
 	case attr_reserved_clusters:
 		return reserved_clusters_store(sbi, buf, len);
 	case attr_pointer_ui:
 		if (!ptr)
 			return 0;
 		ret = kstrtoul(skip_spaces(buf), 0, &t);
 		if (ret)
 			return ret;
 		if (a->attr_ptr == ptr_ext4_super_block_offset)
 			*((__le32 *) ptr) = cpu_to_le32(t);
 		else
 			*((unsigned int *) ptr) = t;
 		return len;
 	case attr_inode_readahead:
 		return inode_readahead_blks_store(sbi, buf, len);
 	case attr_trigger_test_error:
 		return trigger_test_error(sbi, buf, len);
 	}
 	return 0;
 }

 static void ext4_sb_release(struct kobject *kobj)
 {
 	struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
 						s_kobj);
 	complete(&sbi->s_kobj_unregister);
 }

 static const struct sysfs_ops ext4_attr_ops = {
 	.show	= ext4_attr_show,
 	.store	= ext4_attr_store,
 };

 static struct kobj_type ext4_sb_ktype = {
 	.default_attrs	= ext4_attrs,
 	.sysfs_ops	= &ext4_attr_ops,
 	.release	= ext4_sb_release,
 };

 static struct kobj_type ext4_feat_ktype = {
 	.default_attrs	= ext4_feat_attrs,
 	.sysfs_ops	= &ext4_attr_ops,
 	.release	= (void (*)(struct kobject *))kfree,
 };

 static struct kobject *ext4_root;

 static struct kobject *ext4_feat;

 int ext4_register_sysfs(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	int err;

 	init_completion(&sbi->s_kobj_unregister);
 	err = kobject_init_and_add(&sbi->s_kobj, &ext4_sb_ktype, ext4_root,
 				   "%s", sb->s_id);
 	if (err) {
 		kobject_put(&sbi->s_kobj);
 		wait_for_completion(&sbi->s_kobj_unregister);
 		return err;
 	}

 	if (ext4_proc_root)
 		sbi->s_proc = proc_mkdir(sb->s_id, ext4_proc_root);
 	if (sbi->s_proc) {
 		proc_create_single_data("options", S_IRUGO, sbi->s_proc,
 				ext4_seq_options_show, sb);
 		proc_create_single_data("es_shrinker_info", S_IRUGO,
 				sbi->s_proc, ext4_seq_es_shrinker_info_show,
 				sb);
 		proc_create_seq_data("mb_groups", S_IRUGO, sbi->s_proc,
 				&ext4_mb_seq_groups_ops, sb);
 	}
 	return 0;
 }

 void ext4_unregister_sysfs(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);

 	if (sbi->s_proc)
 		remove_proc_subtree(sb->s_id, ext4_proc_root);
 	kobject_del(&sbi->s_kobj);
 }

 int __init ext4_init_sysfs(void)
 {
 	int ret;

 	ext4_root = kobject_create_and_add("ext4", fs_kobj);
 	if (!ext4_root)
 		return -ENOMEM;

 	ext4_feat = kzalloc(sizeof(*ext4_feat), GFP_KERNEL);
 	if (!ext4_feat) {
 		ret = -ENOMEM;
 		goto root_err;
 	}

 	ret = kobject_init_and_add(ext4_feat, &ext4_feat_ktype,
 				   ext4_root, "features");
 	if (ret)
 		goto feat_err;

 	ext4_proc_root = proc_mkdir(proc_dirname, NULL);
 	return ret;

 feat_err:
 	kobject_put(ext4_feat);
 	ext4_feat = NULL;
 root_err:
 	kobject_put(ext4_root);
 	ext4_root = NULL;
 	return ret;
 }

 void ext4_exit_sysfs(void)
 {
 	kobject_put(ext4_feat);
 	ext4_feat = NULL;
 	kobject_put(ext4_root);
 	ext4_root = NULL;
 	remove_proc_entry(proc_dirname, NULL);
 	ext4_proc_root = NULL;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* linux/fs/ext4/sysfs.c
	*
	* Copyright (C) 1992, 1993, 1994, 1995
	* Remy Card (card@masi.ibp.fr)
	* Theodore Ts'o (tytso@mit.edu)
	*
	*/

	#include <linux/time.h>
	#include <linux/fs.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>
	#include <linux/proc_fs.h>

	#include "ext4.h"
	#include "ext4_jbd2.h"

	typedef enum {
	attr_noop,
	attr_delayed_allocation_blocks,
	attr_session_write_kbytes,
	attr_lifetime_write_kbytes,
	attr_reserved_clusters,
	attr_inode_readahead,
	attr_trigger_test_error,
	attr_first_error_time,
	attr_last_error_time,
	attr_feature,
	attr_pointer_ui,
	attr_pointer_atomic,
	attr_journal_task,
	} attr_id_t;

	typedef enum {
	ptr_explicit,
	ptr_ext4_sb_info_offset,
	ptr_ext4_super_block_offset,
	} attr_ptr_t;

	static const char proc_dirname[] = "fs/ext4";
	static struct proc_dir_entry *ext4_proc_root;

	struct ext4_attr {
	struct attribute attr;
	short attr_id;
	short attr_ptr;
	union {
	int offset;
	void *explicit_ptr;
	} u;
	};

	static ssize_t session_write_kbytes_show(struct ext4_sb_info sbi, char buf)
	{
	struct super_block *sb = sbi->s_buddy_cache->i_sb;

	if (!sb->s_bdev->bd_part)
	return snprintf(buf, PAGE_SIZE, "0\n");
	return snprintf(buf, PAGE_SIZE, "%lu\n",
	(part_stat_read(sb->s_bdev->bd_part,
	sectors[STAT_WRITE]) -
	sbi->s_sectors_written_start) >> 1);
	}

	static ssize_t lifetime_write_kbytes_show(struct ext4_sb_info sbi, char buf)
	{
	struct super_block *sb = sbi->s_buddy_cache->i_sb;

	if (!sb->s_bdev->bd_part)
	return snprintf(buf, PAGE_SIZE, "0\n");
	return snprintf(buf, PAGE_SIZE, "%llu\n",
	(unsigned long long)(sbi->s_kbytes_written +
	((part_stat_read(sb->s_bdev->bd_part,
	sectors[STAT_WRITE]) -
	EXT4_SB(sb)->s_sectors_written_start) >> 1)));
	}

	static ssize_t inode_readahead_blks_store(struct ext4_sb_info *sbi,
	const char *buf, size_t count)
	{
	unsigned long t;
	int ret;

	ret = kstrtoul(skip_spaces(buf), 0, &t);
	if (ret)
	return ret;

	if (t && (!is_power_of_2(t) \|\| t > 0x40000000))
	return -EINVAL;

	sbi->s_inode_readahead_blks = t;
	return count;
	}

	static ssize_t reserved_clusters_store(struct ext4_sb_info *sbi,
	const char *buf, size_t count)
	{
	unsigned long long val;
	ext4_fsblk_t clusters = (ext4_blocks_count(sbi->s_es) >>
	sbi->s_cluster_bits);
	int ret;

	ret = kstrtoull(skip_spaces(buf), 0, &val);
	if (ret \|\| val >= clusters)
	return -EINVAL;

	atomic64_set(&sbi->s_resv_clusters, val);
	return count;
	}

	static ssize_t trigger_test_error(struct ext4_sb_info *sbi,
	const char *buf, size_t count)
	{
	int len = count;

	if (!capable(CAP_SYS_ADMIN))
	return -EPERM;

	if (len && buf[len-1] == '\n')
	len--;

	if (len)
	ext4_error(sbi->s_sb, "%.*s", len, buf);
	return count;
	}

	static ssize_t journal_task_show(struct ext4_sb_info sbi, char buf)
	{
	if (!sbi->s_journal)
	return snprintf(buf, PAGE_SIZE, "<none>\n");
	return snprintf(buf, PAGE_SIZE, "%d\n",
	task_pid_vnr(sbi->s_journal->j_task));
	}

	#define EXT4_ATTR(_name,_mode,_id) \
	static struct ext4_attr ext4_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode }, \
	.attr_id = attr_##_id, \
	}

	#define EXT4_ATTR_FUNC(_name,_mode) EXT4_ATTR(_name,_mode,_name)

	#define EXT4_ATTR_FEATURE(_name) EXT4_ATTR(_name, 0444, feature)

	#define EXT4_ATTR_OFFSET(_name,_mode,_id,_struct,_elname) \
	static struct ext4_attr ext4_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode }, \
	.attr_id = attr_##_id, \
	.attr_ptr = ptr_##_struct##_offset, \
	.u = { \
	.offset = offsetof(struct _struct, _elname),\
	}, \
	}

	#define EXT4_RO_ATTR_ES_UI(_name,_elname) \
	EXT4_ATTR_OFFSET(_name, 0444, pointer_ui, ext4_super_block, _elname)

	#define EXT4_RW_ATTR_SBI_UI(_name,_elname) \
	EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname)

	#define EXT4_ATTR_PTR(_name,_mode,_id,_ptr) \
	static struct ext4_attr ext4_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode }, \
	.attr_id = attr_##_id, \
	.attr_ptr = ptr_explicit, \
	.u = { \
	.explicit_ptr = _ptr, \
	}, \
	}

	#define ATTR_LIST(name) &ext4_attr_##name.attr

	EXT4_ATTR_FUNC(delayed_allocation_blocks, 0444);
	EXT4_ATTR_FUNC(session_write_kbytes, 0444);
	EXT4_ATTR_FUNC(lifetime_write_kbytes, 0444);
	EXT4_ATTR_FUNC(reserved_clusters, 0644);

	EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
	ext4_sb_info, s_inode_readahead_blks);
	EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
	EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
	EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
	EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
	EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
	EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
	EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
	EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
	EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
	EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
	EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
	EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
	EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
	EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
	EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
	EXT4_RO_ATTR_ES_UI(errors_count, s_error_count);
	EXT4_ATTR(first_error_time, 0444, first_error_time);
	EXT4_ATTR(last_error_time, 0444, last_error_time);
	EXT4_ATTR(journal_task, 0444, journal_task);

	static unsigned int old_bump_val = 128;
	EXT4_ATTR_PTR(max_writeback_mb_bump, 0444, pointer_ui, &old_bump_val);

	static struct attribute *ext4_attrs[] = {
	ATTR_LIST(delayed_allocation_blocks),
	ATTR_LIST(session_write_kbytes),
	ATTR_LIST(lifetime_write_kbytes),
	ATTR_LIST(reserved_clusters),
	ATTR_LIST(inode_readahead_blks),
	ATTR_LIST(inode_goal),
	ATTR_LIST(mb_stats),
	ATTR_LIST(mb_max_to_scan),
	ATTR_LIST(mb_min_to_scan),
	ATTR_LIST(mb_order2_req),
	ATTR_LIST(mb_stream_req),
	ATTR_LIST(mb_group_prealloc),
	ATTR_LIST(max_writeback_mb_bump),
	ATTR_LIST(extent_max_zeroout_kb),
	ATTR_LIST(trigger_fs_error),
	ATTR_LIST(err_ratelimit_interval_ms),
	ATTR_LIST(err_ratelimit_burst),
	ATTR_LIST(warning_ratelimit_interval_ms),
	ATTR_LIST(warning_ratelimit_burst),
	ATTR_LIST(msg_ratelimit_interval_ms),
	ATTR_LIST(msg_ratelimit_burst),
	ATTR_LIST(errors_count),
	ATTR_LIST(first_error_time),
	ATTR_LIST(last_error_time),
	ATTR_LIST(journal_task),
	NULL,
	};

	/* Features this copy of ext4 supports */
	EXT4_ATTR_FEATURE(lazy_itable_init);
	EXT4_ATTR_FEATURE(batched_discard);
	EXT4_ATTR_FEATURE(meta_bg_resize);
	#ifdef CONFIG_FS_ENCRYPTION
	EXT4_ATTR_FEATURE(encryption);
	#endif
	EXT4_ATTR_FEATURE(metadata_csum_seed);

	static struct attribute *ext4_feat_attrs[] = {
	ATTR_LIST(lazy_itable_init),
	ATTR_LIST(batched_discard),
	ATTR_LIST(meta_bg_resize),
	#ifdef CONFIG_FS_ENCRYPTION
	ATTR_LIST(encryption),
	#endif
	ATTR_LIST(metadata_csum_seed),
	NULL,
	};

	static void calc_ptr(struct ext4_attr a, struct ext4_sb_info *sbi)
	{
	switch (a->attr_ptr) {
	case ptr_explicit:
	return a->u.explicit_ptr;
	case ptr_ext4_sb_info_offset:
	return (void ) (((char ) sbi) + a->u.offset);
	case ptr_ext4_super_block_offset:
	return (void ) (((char ) sbi->s_es) + a->u.offset);
	}
	return NULL;
	}

	static ssize_t __print_tstamp(char *buf, __le32 lo, __u8 hi)
	{
	return snprintf(buf, PAGE_SIZE, "%lld",
	((time64_t)hi << 32) + le32_to_cpu(lo));
	}

	#define print_tstamp(buf, es, tstamp) \
	__print_tstamp(buf, (es)->tstamp, (es)->tstamp ## _hi)

	static ssize_t ext4_attr_show(struct kobject *kobj,
	struct attribute attr, char buf)
	{
	struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
	s_kobj);
	struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
	void *ptr = calc_ptr(a, sbi);

	switch (a->attr_id) {
	case attr_delayed_allocation_blocks:
	return snprintf(buf, PAGE_SIZE, "%llu\n",
	(s64) EXT4_C2B(sbi,
	percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
	case attr_session_write_kbytes:
	return session_write_kbytes_show(sbi, buf);
	case attr_lifetime_write_kbytes:
	return lifetime_write_kbytes_show(sbi, buf);
	case attr_reserved_clusters:
	return snprintf(buf, PAGE_SIZE, "%llu\n",
	(unsigned long long)
	atomic64_read(&sbi->s_resv_clusters));
	case attr_inode_readahead:
	case attr_pointer_ui:
	if (!ptr)
	return 0;
	if (a->attr_ptr == ptr_ext4_super_block_offset)
	return snprintf(buf, PAGE_SIZE, "%u\n",
	le32_to_cpup(ptr));
	else
	return snprintf(buf, PAGE_SIZE, "%u\n",
	((unsigned int ) ptr));
	case attr_pointer_atomic:
	if (!ptr)
	return 0;
	return snprintf(buf, PAGE_SIZE, "%d\n",
	atomic_read((atomic_t *) ptr));
	case attr_feature:
	return snprintf(buf, PAGE_SIZE, "supported\n");
	case attr_first_error_time:
	return print_tstamp(buf, sbi->s_es, s_first_error_time);
	case attr_last_error_time:
	return print_tstamp(buf, sbi->s_es, s_last_error_time);
	case attr_journal_task:
	return journal_task_show(sbi, buf);
	}

	return 0;
	}

	static ssize_t ext4_attr_store(struct kobject *kobj,
	struct attribute *attr,
	const char *buf, size_t len)
	{
	struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
	s_kobj);
	struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
	void *ptr = calc_ptr(a, sbi);
	unsigned long t;
	int ret;

	switch (a->attr_id) {
	case attr_reserved_clusters:
	return reserved_clusters_store(sbi, buf, len);
	case attr_pointer_ui:
	if (!ptr)
	return 0;
	ret = kstrtoul(skip_spaces(buf), 0, &t);
	if (ret)
	return ret;
	if (a->attr_ptr == ptr_ext4_super_block_offset)
	((__le32 ) ptr) = cpu_to_le32(t);
	else
	((unsigned int ) ptr) = t;
	return len;
	case attr_inode_readahead:
	return inode_readahead_blks_store(sbi, buf, len);
	case attr_trigger_test_error:
	return trigger_test_error(sbi, buf, len);
	}
	return 0;
	}

	static void ext4_sb_release(struct kobject *kobj)
	{
	struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
	s_kobj);
	complete(&sbi->s_kobj_unregister);
	}

	static const struct sysfs_ops ext4_attr_ops = {
	.show = ext4_attr_show,
	.store = ext4_attr_store,
	};

	static struct kobj_type ext4_sb_ktype = {
	.default_attrs = ext4_attrs,
	.sysfs_ops = &ext4_attr_ops,
	.release = ext4_sb_release,
	};

	static struct kobj_type ext4_feat_ktype = {
	.default_attrs = ext4_feat_attrs,
	.sysfs_ops = &ext4_attr_ops,
	.release = (void ()(struct kobject ))kfree,
	};

	static struct kobject *ext4_root;

	static struct kobject *ext4_feat;

	int ext4_register_sysfs(struct super_block *sb)
	{
	struct ext4_sb_info *sbi = EXT4_SB(sb);
	int err;

	init_completion(&sbi->s_kobj_unregister);
	err = kobject_init_and_add(&sbi->s_kobj, &ext4_sb_ktype, ext4_root,
	"%s", sb->s_id);
	if (err) {
	kobject_put(&sbi->s_kobj);
	wait_for_completion(&sbi->s_kobj_unregister);
	return err;
	}

	if (ext4_proc_root)
	sbi->s_proc = proc_mkdir(sb->s_id, ext4_proc_root);
	if (sbi->s_proc) {
	proc_create_single_data("options", S_IRUGO, sbi->s_proc,
	ext4_seq_options_show, sb);
	proc_create_single_data("es_shrinker_info", S_IRUGO,
	sbi->s_proc, ext4_seq_es_shrinker_info_show,
	sb);
	proc_create_seq_data("mb_groups", S_IRUGO, sbi->s_proc,
	&ext4_mb_seq_groups_ops, sb);
	}
	return 0;
	}

	void ext4_unregister_sysfs(struct super_block *sb)
	{
	struct ext4_sb_info *sbi = EXT4_SB(sb);

	if (sbi->s_proc)
	remove_proc_subtree(sb->s_id, ext4_proc_root);
	kobject_del(&sbi->s_kobj);
	}

	int __init ext4_init_sysfs(void)
	{
	int ret;

	ext4_root = kobject_create_and_add("ext4", fs_kobj);
	if (!ext4_root)
	return -ENOMEM;

	ext4_feat = kzalloc(sizeof(*ext4_feat), GFP_KERNEL);
	if (!ext4_feat) {
	ret = -ENOMEM;
	goto root_err;
	}

	ret = kobject_init_and_add(ext4_feat, &ext4_feat_ktype,
	ext4_root, "features");
	if (ret)
	goto feat_err;

	ext4_proc_root = proc_mkdir(proc_dirname, NULL);
	return ret;

	feat_err:
	kobject_put(ext4_feat);
	ext4_feat = NULL;
	root_err:
	kobject_put(ext4_root);
	ext4_root = NULL;
	return ret;
	}

	void ext4_exit_sysfs(void)
	{
	kobject_put(ext4_feat);
	ext4_feat = NULL;
	kobject_put(ext4_root);
	ext4_root = NULL;
	remove_proc_entry(proc_dirname, NULL);
	ext4_proc_root = NULL;
	}