fs/pstore/inode.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Persistent Storage - ramfs parts.
  *
  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
  */

 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/fsnotify.h>
 #include <linux/pagemap.h>
 #include <linux/highmem.h>
 #include <linux/time.h>
 #include <linux/init.h>
 #include <linux/list.h>
 #include <linux/string.h>
 #include <linux/mount.h>
 #include <linux/seq_file.h>
 #include <linux/ramfs.h>
 #include <linux/parser.h>
 #include <linux/sched.h>
 #include <linux/magic.h>
 #include <linux/pstore.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/uaccess.h>

 #include "internal.h"

 #define	PSTORE_NAMELEN	64

 static DEFINE_SPINLOCK(allpstore_lock);
 static LIST_HEAD(allpstore);

 struct pstore_private {
 	struct list_head list;
 	struct pstore_record *record;
 	size_t total_size;
 };

 struct pstore_ftrace_seq_data {
 	const void *ptr;
 	size_t off;
 	size_t size;
 };

 #define REC_SIZE sizeof(struct pstore_ftrace_record)

 static void free_pstore_private(struct pstore_private *private)
 {
 	if (!private)
 		return;
 	if (private->record) {
 		kfree(private->record->buf);
 		kfree(private->record);
 	}
 	kfree(private);
 }

 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
 {
 	struct pstore_private *ps = s->private;
 	struct pstore_ftrace_seq_data *data;

 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return NULL;

 	data->off = ps->total_size % REC_SIZE;
 	data->off += *pos * REC_SIZE;
 	if (data->off + REC_SIZE > ps->total_size) {
 		kfree(data);
 		return NULL;
 	}

 	return data;

 }

 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
 {
 	kfree(v);
 }

 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
 {
 	struct pstore_private *ps = s->private;
 	struct pstore_ftrace_seq_data *data = v;

 	(*pos)++;
 	data->off += REC_SIZE;
 	if (data->off + REC_SIZE > ps->total_size)
 		return NULL;

 	return data;
 }

 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
 {
 	struct pstore_private *ps = s->private;
 	struct pstore_ftrace_seq_data *data = v;
 	struct pstore_ftrace_record *rec;

 	if (!data)
 		return 0;

 	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);

 	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
 		   pstore_ftrace_decode_cpu(rec),
 		   pstore_ftrace_read_timestamp(rec),
 		   rec->ip, rec->parent_ip, (void *)rec->ip,
 		   (void *)rec->parent_ip);

 	return 0;
 }

 static const struct seq_operations pstore_ftrace_seq_ops = {
 	.start	= pstore_ftrace_seq_start,
 	.next	= pstore_ftrace_seq_next,
 	.stop	= pstore_ftrace_seq_stop,
 	.show	= pstore_ftrace_seq_show,
 };

 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
 						size_t count, loff_t *ppos)
 {
 	struct seq_file *sf = file->private_data;
 	struct pstore_private *ps = sf->private;

 	if (ps->record->type == PSTORE_TYPE_FTRACE)
 		return seq_read(file, userbuf, count, ppos);
 	return simple_read_from_buffer(userbuf, count, ppos,
 				       ps->record->buf, ps->total_size);
 }

 static int pstore_file_open(struct inode *inode, struct file *file)
 {
 	struct pstore_private *ps = inode->i_private;
 	struct seq_file *sf;
 	int err;
 	const struct seq_operations *sops = NULL;

 	if (ps->record->type == PSTORE_TYPE_FTRACE)
 		sops = &pstore_ftrace_seq_ops;

 	err = seq_open(file, sops);
 	if (err < 0)
 		return err;

 	sf = file->private_data;
 	sf->private = ps;

 	return 0;
 }

 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
 {
 	struct seq_file *sf = file->private_data;

 	if (sf->op)
 		return seq_lseek(file, off, whence);
 	return default_llseek(file, off, whence);
 }

 static const struct file_operations pstore_file_operations = {
 	.open		= pstore_file_open,
 	.read		= pstore_file_read,
 	.llseek		= pstore_file_llseek,
 	.release	= seq_release,
 };

 /*
  * When a file is unlinked from our file system we call the
  * platform driver to erase the record from persistent store.
  */
 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 {
 	struct pstore_private *p = d_inode(dentry)->i_private;
 	struct pstore_record *record = p->record;

 	if (!record->psi->erase)
 		return -EPERM;

 	mutex_lock(&record->psi->read_mutex);
 	record->psi->erase(record);
 	mutex_unlock(&record->psi->read_mutex);

 	return simple_unlink(dir, dentry);
 }

 static void pstore_evict_inode(struct inode *inode)
 {
 	struct pstore_private	*p = inode->i_private;
 	unsigned long		flags;

 	clear_inode(inode);
 	if (p) {
 		spin_lock_irqsave(&allpstore_lock, flags);
 		list_del(&p->list);
 		spin_unlock_irqrestore(&allpstore_lock, flags);
 		free_pstore_private(p);
 	}
 }

 static const struct inode_operations pstore_dir_inode_operations = {
 	.lookup		= simple_lookup,
 	.unlink		= pstore_unlink,
 };

 static struct inode *pstore_get_inode(struct super_block *sb)
 {
 	struct inode *inode = new_inode(sb);
 	if (inode) {
 		inode->i_ino = get_next_ino();
 		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 	}
 	return inode;
 }

 enum {
 	Opt_kmsg_bytes, Opt_err
 };

 static const match_table_t tokens = {
 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
 	{Opt_err, NULL}
 };

 static void parse_options(char *options)
 {
 	char		*p;
 	substring_t	args[MAX_OPT_ARGS];
 	int		option;

 	if (!options)
 		return;

 	while ((p = strsep(&options, ",")) != NULL) {
 		int token;

 		if (!*p)
 			continue;

 		token = match_token(p, tokens, args);
 		switch (token) {
 		case Opt_kmsg_bytes:
 			if (!match_int(&args[0], &option))
 				pstore_set_kmsg_bytes(option);
 			break;
 		}
 	}
 }

 /*
  * Display the mount options in /proc/mounts.
  */
 static int pstore_show_options(struct seq_file *m, struct dentry *root)
 {
 	if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
 		seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
 	return 0;
 }

 static int pstore_remount(struct super_block *sb, int *flags, char *data)
 {
 	sync_filesystem(sb);
 	parse_options(data);

 	return 0;
 }

 static const struct super_operations pstore_ops = {
 	.statfs		= simple_statfs,
 	.drop_inode	= generic_delete_inode,
 	.evict_inode	= pstore_evict_inode,
 	.remount_fs	= pstore_remount,
 	.show_options	= pstore_show_options,
 };

 static struct super_block *pstore_sb;

 bool pstore_is_mounted(void)
 {
 	return pstore_sb != NULL;
 }

 /*
  * Make a regular file in the root directory of our file system.
  * Load it up with "size" bytes of data from "buf".
  * Set the mtime & ctime to the date that this record was originally stored.
  */
 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 {
 	struct dentry		*dentry;
 	struct inode		*inode;
 	int			rc = 0;
 	char			name[PSTORE_NAMELEN];
 	struct pstore_private	*private, *pos;
 	unsigned long		flags;
 	size_t			size = record->size + record->ecc_notice_size;

 	WARN_ON(!inode_is_locked(d_inode(root)));

 	spin_lock_irqsave(&allpstore_lock, flags);
 	list_for_each_entry(pos, &allpstore, list) {
 		if (pos->record->type == record->type &&
 		    pos->record->id == record->id &&
 		    pos->record->psi == record->psi) {
 			rc = -EEXIST;
 			break;
 		}
 	}
 	spin_unlock_irqrestore(&allpstore_lock, flags);
 	if (rc)
 		return rc;

 	rc = -ENOMEM;
 	inode = pstore_get_inode(root->d_sb);
 	if (!inode)
 		goto fail;
 	inode->i_mode = S_IFREG | 0444;
 	inode->i_fop = &pstore_file_operations;
 	scnprintf(name, sizeof(name), "%s-%s-%llu%s",
 			pstore_type_to_name(record->type),
 			record->psi->name, record->id,
 			record->compressed ? ".enc.z" : "");

 	private = kzalloc(sizeof(*private), GFP_KERNEL);
 	if (!private)
 		goto fail_inode;

 	dentry = d_alloc_name(root, name);
 	if (!dentry)
 		goto fail_private;

 	private->record = record;
 	inode->i_size = private->total_size = size;
 	inode->i_private = private;

 	if (record->time.tv_sec)
 		inode->i_mtime = inode->i_ctime = record->time;

 	d_add(dentry, inode);

 	spin_lock_irqsave(&allpstore_lock, flags);
 	list_add(&private->list, &allpstore);
 	spin_unlock_irqrestore(&allpstore_lock, flags);

 	return 0;

 fail_private:
 	free_pstore_private(private);
 fail_inode:
 	iput(inode);

 fail:
 	return rc;
 }

 /*
  * Read all the records from the persistent store. Create
  * files in our filesystem.  Don't warn about -EEXIST errors
  * when we are re-scanning the backing store looking to add new
  * error records.
  */
 void pstore_get_records(int quiet)
 {
 	struct pstore_info *psi = psinfo;
 	struct dentry *root;

 	if (!psi || !pstore_sb)
 		return;

 	root = pstore_sb->s_root;

 	inode_lock(d_inode(root));
 	pstore_get_backend_records(psi, root, quiet);
 	inode_unlock(d_inode(root));
 }

 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct inode *inode;

 	pstore_sb = sb;

 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
 	sb->s_blocksize		= PAGE_SIZE;
 	sb->s_blocksize_bits	= PAGE_SHIFT;
 	sb->s_magic		= PSTOREFS_MAGIC;
 	sb->s_op		= &pstore_ops;
 	sb->s_time_gran		= 1;

 	parse_options(data);

 	inode = pstore_get_inode(sb);
 	if (inode) {
 		inode->i_mode = S_IFDIR | 0750;
 		inode->i_op = &pstore_dir_inode_operations;
 		inode->i_fop = &simple_dir_operations;
 		inc_nlink(inode);
 	}
 	sb->s_root = d_make_root(inode);
 	if (!sb->s_root)
 		return -ENOMEM;

 	pstore_get_records(0);

 	return 0;
 }

 static struct dentry *pstore_mount(struct file_system_type *fs_type,
 	int flags, const char *dev_name, void *data)
 {
 	return mount_single(fs_type, flags, data, pstore_fill_super);
 }

 static void pstore_kill_sb(struct super_block *sb)
 {
 	kill_litter_super(sb);
 	pstore_sb = NULL;
 }

 static struct file_system_type pstore_fs_type = {
 	.owner          = THIS_MODULE,
 	.name		= "pstore",
 	.mount		= pstore_mount,
 	.kill_sb	= pstore_kill_sb,
 };

 int __init pstore_init_fs(void)
 {
 	int err;

 	/* Create a convenient mount point for people to access pstore */
 	err = sysfs_create_mount_point(fs_kobj, "pstore");
 	if (err)
 		goto out;

 	err = register_filesystem(&pstore_fs_type);
 	if (err < 0)
 		sysfs_remove_mount_point(fs_kobj, "pstore");

 out:
 	return err;
 }

 void __exit pstore_exit_fs(void)
 {
 	unregister_filesystem(&pstore_fs_type);
 	sysfs_remove_mount_point(fs_kobj, "pstore");
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Persistent Storage - ramfs parts.
	*
	* Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
	*/

	#include <linux/module.h>
	#include <linux/fs.h>
	#include <linux/fsnotify.h>
	#include <linux/pagemap.h>
	#include <linux/highmem.h>
	#include <linux/time.h>
	#include <linux/init.h>
	#include <linux/list.h>
	#include <linux/string.h>
	#include <linux/mount.h>
	#include <linux/seq_file.h>
	#include <linux/ramfs.h>
	#include <linux/parser.h>
	#include <linux/sched.h>
	#include <linux/magic.h>
	#include <linux/pstore.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>
	#include <linux/uaccess.h>

	#include "internal.h"

	#define PSTORE_NAMELEN 64

	static DEFINE_SPINLOCK(allpstore_lock);
	static LIST_HEAD(allpstore);

	struct pstore_private {
	struct list_head list;
	struct pstore_record *record;
	size_t total_size;
	};

	struct pstore_ftrace_seq_data {
	const void *ptr;
	size_t off;
	size_t size;
	};

	#define REC_SIZE sizeof(struct pstore_ftrace_record)

	static void free_pstore_private(struct pstore_private *private)
	{
	if (!private)
	return;
	if (private->record) {
	kfree(private->record->buf);
	kfree(private->record);
	}
	kfree(private);
	}

	static void pstore_ftrace_seq_start(struct seq_file s, loff_t *pos)
	{
	struct pstore_private *ps = s->private;
	struct pstore_ftrace_seq_data *data;

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data)
	return NULL;

	data->off = ps->total_size % REC_SIZE;
	data->off += pos REC_SIZE;
	if (data->off + REC_SIZE > ps->total_size) {
	kfree(data);
	return NULL;
	}

	return data;

	}

	static void pstore_ftrace_seq_stop(struct seq_file s, void v)
	{
	kfree(v);
	}

	static void pstore_ftrace_seq_next(struct seq_file s, void v, loff_t pos)
	{
	struct pstore_private *ps = s->private;
	struct pstore_ftrace_seq_data *data = v;

	(*pos)++;
	data->off += REC_SIZE;
	if (data->off + REC_SIZE > ps->total_size)
	return NULL;

	return data;
	}

	static int pstore_ftrace_seq_show(struct seq_file s, void v)
	{
	struct pstore_private *ps = s->private;
	struct pstore_ftrace_seq_data *data = v;
	struct pstore_ftrace_record *rec;

	if (!data)
	return 0;

	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);

	seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %ps <- %pS\n",
	pstore_ftrace_decode_cpu(rec),
	pstore_ftrace_read_timestamp(rec),
	rec->ip, rec->parent_ip, (void *)rec->ip,
	(void *)rec->parent_ip);

	return 0;
	}

	static const struct seq_operations pstore_ftrace_seq_ops = {
	.start = pstore_ftrace_seq_start,
	.next = pstore_ftrace_seq_next,
	.stop = pstore_ftrace_seq_stop,
	.show = pstore_ftrace_seq_show,
	};

	static ssize_t pstore_file_read(struct file file, char __user userbuf,
	size_t count, loff_t *ppos)
	{
	struct seq_file *sf = file->private_data;
	struct pstore_private *ps = sf->private;

	if (ps->record->type == PSTORE_TYPE_FTRACE)
	return seq_read(file, userbuf, count, ppos);
	return simple_read_from_buffer(userbuf, count, ppos,
	ps->record->buf, ps->total_size);
	}

	static int pstore_file_open(struct inode inode, struct file file)
	{
	struct pstore_private *ps = inode->i_private;
	struct seq_file *sf;
	int err;
	const struct seq_operations *sops = NULL;

	if (ps->record->type == PSTORE_TYPE_FTRACE)
	sops = &pstore_ftrace_seq_ops;

	err = seq_open(file, sops);
	if (err < 0)
	return err;

	sf = file->private_data;
	sf->private = ps;

	return 0;
	}

	static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
	{
	struct seq_file *sf = file->private_data;

	if (sf->op)
	return seq_lseek(file, off, whence);
	return default_llseek(file, off, whence);
	}

	static const struct file_operations pstore_file_operations = {
	.open = pstore_file_open,
	.read = pstore_file_read,
	.llseek = pstore_file_llseek,
	.release = seq_release,
	};

	/*
	* When a file is unlinked from our file system we call the
	* platform driver to erase the record from persistent store.
	*/
	static int pstore_unlink(struct inode dir, struct dentry dentry)
	{
	struct pstore_private *p = d_inode(dentry)->i_private;
	struct pstore_record *record = p->record;

	if (!record->psi->erase)
	return -EPERM;

	mutex_lock(&record->psi->read_mutex);
	record->psi->erase(record);
	mutex_unlock(&record->psi->read_mutex);

	return simple_unlink(dir, dentry);
	}

	static void pstore_evict_inode(struct inode *inode)
	{
	struct pstore_private *p = inode->i_private;
	unsigned long flags;

	clear_inode(inode);
	if (p) {
	spin_lock_irqsave(&allpstore_lock, flags);
	list_del(&p->list);
	spin_unlock_irqrestore(&allpstore_lock, flags);
	free_pstore_private(p);
	}
	}

	static const struct inode_operations pstore_dir_inode_operations = {
	.lookup = simple_lookup,
	.unlink = pstore_unlink,
	};

	static struct inode pstore_get_inode(struct super_block sb)
	{
	struct inode *inode = new_inode(sb);
	if (inode) {
	inode->i_ino = get_next_ino();
	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
	}
	return inode;
	}

	enum {
	Opt_kmsg_bytes, Opt_err
	};

	static const match_table_t tokens = {
	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
	{Opt_err, NULL}
	};

	static void parse_options(char *options)
	{
	char *p;
	substring_t args[MAX_OPT_ARGS];
	int option;

	if (!options)
	return;

	while ((p = strsep(&options, ",")) != NULL) {
	int token;

	if (!*p)
	continue;

	token = match_token(p, tokens, args);
	switch (token) {
	case Opt_kmsg_bytes:
	if (!match_int(&args[0], &option))
	pstore_set_kmsg_bytes(option);
	break;
	}
	}
	}

	/*
	* Display the mount options in /proc/mounts.
	*/
	static int pstore_show_options(struct seq_file m, struct dentry root)
	{
	if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
	seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
	return 0;
	}

	static int pstore_remount(struct super_block sb, int flags, char *data)
	{
	sync_filesystem(sb);
	parse_options(data);

	return 0;
	}

	static const struct super_operations pstore_ops = {
	.statfs = simple_statfs,
	.drop_inode = generic_delete_inode,
	.evict_inode = pstore_evict_inode,
	.remount_fs = pstore_remount,
	.show_options = pstore_show_options,
	};

	static struct super_block *pstore_sb;

	bool pstore_is_mounted(void)
	{
	return pstore_sb != NULL;
	}

	/*
	* Make a regular file in the root directory of our file system.
	* Load it up with "size" bytes of data from "buf".
	* Set the mtime & ctime to the date that this record was originally stored.
	*/
	int pstore_mkfile(struct dentry root, struct pstore_record record)
	{
	struct dentry *dentry;
	struct inode *inode;
	int rc = 0;
	char name[PSTORE_NAMELEN];
	struct pstore_private private, pos;
	unsigned long flags;
	size_t size = record->size + record->ecc_notice_size;

	WARN_ON(!inode_is_locked(d_inode(root)));

	spin_lock_irqsave(&allpstore_lock, flags);
	list_for_each_entry(pos, &allpstore, list) {
	if (pos->record->type == record->type &&
	pos->record->id == record->id &&
	pos->record->psi == record->psi) {
	rc = -EEXIST;
	break;
	}
	}
	spin_unlock_irqrestore(&allpstore_lock, flags);
	if (rc)
	return rc;

	rc = -ENOMEM;
	inode = pstore_get_inode(root->d_sb);
	if (!inode)
	goto fail;
	inode->i_mode = S_IFREG \| 0444;
	inode->i_fop = &pstore_file_operations;
	scnprintf(name, sizeof(name), "%s-%s-%llu%s",
	pstore_type_to_name(record->type),
	record->psi->name, record->id,
	record->compressed ? ".enc.z" : "");

	private = kzalloc(sizeof(*private), GFP_KERNEL);
	if (!private)
	goto fail_inode;

	dentry = d_alloc_name(root, name);
	if (!dentry)
	goto fail_private;

	private->record = record;
	inode->i_size = private->total_size = size;
	inode->i_private = private;

	if (record->time.tv_sec)
	inode->i_mtime = inode->i_ctime = record->time;

	d_add(dentry, inode);

	spin_lock_irqsave(&allpstore_lock, flags);
	list_add(&private->list, &allpstore);
	spin_unlock_irqrestore(&allpstore_lock, flags);

	return 0;

	fail_private:
	free_pstore_private(private);
	fail_inode:
	iput(inode);

	fail:
	return rc;
	}

	/*
	* Read all the records from the persistent store. Create
	* files in our filesystem. Don't warn about -EEXIST errors
	* when we are re-scanning the backing store looking to add new
	* error records.
	*/
	void pstore_get_records(int quiet)
	{
	struct pstore_info *psi = psinfo;
	struct dentry *root;

	if (!psi \|\| !pstore_sb)
	return;

	root = pstore_sb->s_root;

	inode_lock(d_inode(root));
	pstore_get_backend_records(psi, root, quiet);
	inode_unlock(d_inode(root));
	}

	static int pstore_fill_super(struct super_block sb, void data, int silent)
	{
	struct inode *inode;

	pstore_sb = sb;

	sb->s_maxbytes = MAX_LFS_FILESIZE;
	sb->s_blocksize = PAGE_SIZE;
	sb->s_blocksize_bits = PAGE_SHIFT;
	sb->s_magic = PSTOREFS_MAGIC;
	sb->s_op = &pstore_ops;
	sb->s_time_gran = 1;

	parse_options(data);

	inode = pstore_get_inode(sb);
	if (inode) {
	inode->i_mode = S_IFDIR \| 0750;
	inode->i_op = &pstore_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	inc_nlink(inode);
	}
	sb->s_root = d_make_root(inode);
	if (!sb->s_root)
	return -ENOMEM;

	pstore_get_records(0);

	return 0;
	}

	static struct dentry pstore_mount(struct file_system_type fs_type,
	int flags, const char dev_name, void data)
	{
	return mount_single(fs_type, flags, data, pstore_fill_super);
	}

	static void pstore_kill_sb(struct super_block *sb)
	{
	kill_litter_super(sb);
	pstore_sb = NULL;
	}

	static struct file_system_type pstore_fs_type = {
	.owner = THIS_MODULE,
	.name = "pstore",
	.mount = pstore_mount,
	.kill_sb = pstore_kill_sb,
	};

	int __init pstore_init_fs(void)
	{
	int err;

	/* Create a convenient mount point for people to access pstore */
	err = sysfs_create_mount_point(fs_kobj, "pstore");
	if (err)
	goto out;

	err = register_filesystem(&pstore_fs_type);
	if (err < 0)
	sysfs_remove_mount_point(fs_kobj, "pstore");

	out:
	return err;
	}

	void __exit pstore_exit_fs(void)
	{
	unregister_filesystem(&pstore_fs_type);
	sysfs_remove_mount_point(fs_kobj, "pstore");
	}