[linux-block.git] / fs / pstore / inode.c

// 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/uaccess.h>

#include "internal.h"

#define	PSTORE_NAMELEN	64

static DEFINE_MUTEX(records_list_lock);
static LIST_HEAD(records_list);

static DEFINE_MUTEX(pstore_sb_lock);
static struct super_block *pstore_sb;

struct pstore_private {
	struct list_head list;
	struct dentry *dentry;
	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;
	int rc = 0;

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

	/* Make sure we can't race while removing this file. */
	mutex_lock(&records_list_lock);
	if (!list_empty(&p->list))
		list_del_init(&p->list);
	else
		rc = -ENOENT;
	p->dentry = NULL;
	mutex_unlock(&records_list_lock);
	if (rc)
		return rc;

	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;

	clear_inode(inode);
	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 != CONFIG_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 dentry *psinfo_lock_root(void)
{
	struct dentry *root;

	mutex_lock(&pstore_sb_lock);
	/*
	 * Having no backend is fine -- no records appear.
	 * Not being mounted is fine -- nothing to do.
	 */
	if (!psinfo || !pstore_sb) {
		mutex_unlock(&pstore_sb_lock);
		return NULL;
	}

	root = pstore_sb->s_root;
	inode_lock(d_inode(root));
	mutex_unlock(&pstore_sb_lock);

	return root;
}

int pstore_put_backend_records(struct pstore_info *psi)
{
	struct pstore_private *pos, *tmp;
	struct dentry *root;
	int rc = 0;

	root = psinfo_lock_root();
	if (!root)
		return 0;

	mutex_lock(&records_list_lock);
	list_for_each_entry_safe(pos, tmp, &records_list, list) {
		if (pos->record->psi == psi) {
			list_del_init(&pos->list);
			rc = simple_unlink(d_inode(root), pos->dentry);
			if (WARN_ON(rc))
				break;
			d_drop(pos->dentry);
			dput(pos->dentry);
			pos->dentry = NULL;
		}
	}
	mutex_unlock(&records_list_lock);

	inode_unlock(d_inode(root));

	return rc;
}

/*
 * 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;
	size_t			size = record->size + record->ecc_notice_size;

	if (WARN_ON(!inode_is_locked(d_inode(root))))
		return -EINVAL;

	rc = -EEXIST;
	/* Skip records that are already present in the filesystem. */
	mutex_lock(&records_list_lock);
	list_for_each_entry(pos, &records_list, list) {
		if (pos->record->type == record->type &&
		    pos->record->id == record->id &&
		    pos->record->psi == record->psi)
			goto fail;
	}

	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->dentry = dentry;
	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);

	list_add(&private->list, &records_list);
	mutex_unlock(&records_list_lock);

	return 0;

fail_private:
	free_pstore_private(private);
fail_inode:
	iput(inode);
fail:
	mutex_unlock(&records_list_lock);
	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 dentry *root;

	root = psinfo_lock_root();
	if (!root)
		return;

	pstore_get_backend_records(psinfo, root, quiet);
	inode_unlock(d_inode(root));
}

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

	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;

	mutex_lock(&pstore_sb_lock);
	pstore_sb = sb;
	mutex_unlock(&pstore_sb_lock);

	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)
{
	mutex_lock(&pstore_sb_lock);
	WARN_ON(pstore_sb && pstore_sb != sb);

	kill_litter_super(sb);
	pstore_sb = NULL;

	mutex_lock(&records_list_lock);
	INIT_LIST_HEAD(&records_list);
	mutex_unlock(&records_list_lock);

	mutex_unlock(&pstore_sb_lock);
}

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");
}
Commit	Line	Data
45051539	1	// SPDX-License-Identifier: GPL-2.0-only
ca01d6dd TL	2	/*
	3	* Persistent Storage - ramfs parts.
	4	*
	5	* Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
ca01d6dd TL	6	*/
	7
	8	#include <linux/module.h>
	9	#include <linux/fs.h>
	10	#include <linux/fsnotify.h>
	11	#include <linux/pagemap.h>
	12	#include <linux/highmem.h>
	13	#include <linux/time.h>
	14	#include <linux/init.h>
6dda9266	15	#include <linux/list.h>
ca01d6dd TL	16	#include <linux/string.h>
ca01d6dd TL	17	#include <linux/mount.h>
060287b8	18	#include <linux/seq_file.h>
ca01d6dd	19	#include <linux/ramfs.h>
366f7e7a	20	#include <linux/parser.h>
ca01d6dd TL	21	#include <linux/sched.h>
	22	#include <linux/magic.h>
	23	#include <linux/pstore.h>
	24	#include <linux/slab.h>
	25	#include <linux/uaccess.h>
	26
	27	#include "internal.h"
	28
	29	#define PSTORE_NAMELEN 64
	30
db23491c	31	static DEFINE_MUTEX(records_list_lock);
47af61ff	32	static LIST_HEAD(records_list);
6dda9266	33
27e5041a KC	34	static DEFINE_MUTEX(pstore_sb_lock);
	35	static struct super_block *pstore_sb;
	36
ca01d6dd	37	struct pstore_private {
6dda9266	38	struct list_head list;
609e28bb	39	struct dentry *dentry;
83f70f07 KC	40	struct pstore_record *record;
83f70f07 KC	41	size_t total_size;
ca01d6dd TL	42	};
ca01d6dd TL	43
060287b8 AV	44	struct pstore_ftrace_seq_data {
	45	const void *ptr;
	46	size_t off;
	47	size_t size;
	48	};
	49
	50	#define REC_SIZE sizeof(struct pstore_ftrace_record)
	51
1dfff7dd KC	52	static void free_pstore_private(struct pstore_private *private)
	53	{
	54	if (!private)
	55	return;
83f70f07 KC	56	if (private->record) {
	57	kfree(private->record->buf);
	58	kfree(private->record);
	59	}
1dfff7dd KC	60	kfree(private);
	61	}
	62
060287b8 AV	63	static void pstore_ftrace_seq_start(struct seq_file s, loff_t *pos)
	64	{
	65	struct pstore_private *ps = s->private;
	66	struct pstore_ftrace_seq_data *data;
	67
	68	data = kzalloc(sizeof(*data), GFP_KERNEL);
	69	if (!data)
	70	return NULL;
	71
83f70f07	72	data->off = ps->total_size % REC_SIZE;
060287b8	73	data->off += pos REC_SIZE;
83f70f07	74	if (data->off + REC_SIZE > ps->total_size) {
060287b8 AV	75	kfree(data);
	76	return NULL;
	77	}
	78
	79	return data;
	80
	81	}
	82
	83	static void pstore_ftrace_seq_stop(struct seq_file s, void v)
	84	{
	85	kfree(v);
	86	}
	87
	88	static void pstore_ftrace_seq_next(struct seq_file s, void v, loff_t pos)
	89	{
	90	struct pstore_private *ps = s->private;
	91	struct pstore_ftrace_seq_data *data = v;
	92
6c871b73	93	(*pos)++;
060287b8	94	data->off += REC_SIZE;
83f70f07	95	if (data->off + REC_SIZE > ps->total_size)
060287b8 AV	96	return NULL;
060287b8 AV	97
060287b8 AV	98	return data;
	99	}
	100
	101	static int pstore_ftrace_seq_show(struct seq_file s, void v)
	102	{
	103	struct pstore_private *ps = s->private;
	104	struct pstore_ftrace_seq_data *data = v;
83f70f07 KC	105	struct pstore_ftrace_record *rec;
83f70f07 KC	106
6c871b73 VA	107	if (!data)
	108	return 0;
	109
83f70f07	110	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
060287b8	111
d75f773c	112	seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %ps <- %pS\n",
fbccdeb8 JF	113	pstore_ftrace_decode_cpu(rec),
	114	pstore_ftrace_read_timestamp(rec),
	115	rec->ip, rec->parent_ip, (void *)rec->ip,
	116	(void *)rec->parent_ip);
060287b8 AV	117
	118	return 0;
	119	}
	120
	121	static const struct seq_operations pstore_ftrace_seq_ops = {
	122	.start = pstore_ftrace_seq_start,
	123	.next = pstore_ftrace_seq_next,
	124	.stop = pstore_ftrace_seq_stop,
	125	.show = pstore_ftrace_seq_show,
	126	};
	127
fbe0aa1f TL	128	static ssize_t pstore_file_read(struct file file, char __user userbuf,
	129	size_t count, loff_t *ppos)
	130	{
060287b8 AV	131	struct seq_file *sf = file->private_data;
060287b8 AV	132	struct pstore_private *ps = sf->private;
fbe0aa1f	133
83f70f07	134	if (ps->record->type == PSTORE_TYPE_FTRACE)
060287b8	135	return seq_read(file, userbuf, count, ppos);
83f70f07 KC	136	return simple_read_from_buffer(userbuf, count, ppos,
83f70f07 KC	137	ps->record->buf, ps->total_size);
fbe0aa1f TL	138	}
fbe0aa1f TL	139
060287b8 AV	140	static int pstore_file_open(struct inode inode, struct file file)
	141	{
	142	struct pstore_private *ps = inode->i_private;
	143	struct seq_file *sf;
	144	int err;
	145	const struct seq_operations *sops = NULL;
	146
83f70f07	147	if (ps->record->type == PSTORE_TYPE_FTRACE)
060287b8 AV	148	sops = &pstore_ftrace_seq_ops;
	149
	150	err = seq_open(file, sops);
	151	if (err < 0)
	152	return err;
	153
	154	sf = file->private_data;
	155	sf->private = ps;
	156
	157	return 0;
	158	}
	159
965c8e59	160	static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
060287b8 AV	161	{
	162	struct seq_file *sf = file->private_data;
	163
	164	if (sf->op)
965c8e59 AM	165	return seq_lseek(file, off, whence);
965c8e59 AM	166	return default_llseek(file, off, whence);
060287b8 AV	167	}
060287b8 AV	168
fbe0aa1f	169	static const struct file_operations pstore_file_operations = {
060287b8 AV	170	.open = pstore_file_open,
	171	.read = pstore_file_read,
	172	.llseek = pstore_file_llseek,
	173	.release = seq_release,
fbe0aa1f	174	};
ca01d6dd TL	175
	176	/*
	177	* When a file is unlinked from our file system we call the
	178	* platform driver to erase the record from persistent store.
	179	*/
	180	static int pstore_unlink(struct inode dir, struct dentry dentry)
	181	{
2b0143b5	182	struct pstore_private *p = d_inode(dentry)->i_private;
83f70f07	183	struct pstore_record *record = p->record;
7a0ad546	184	int rc = 0;
ca01d6dd	185
a61072aa	186	if (!record->psi->erase)
bf288333	187	return -EPERM;
a61072aa	188
7a0ad546 KC	189	/* Make sure we can't race while removing this file. */
	190	mutex_lock(&records_list_lock);
	191	if (!list_empty(&p->list))
	192	list_del_init(&p->list);
	193	else
	194	rc = -ENOENT;
609e28bb	195	p->dentry = NULL;
7a0ad546 KC	196	mutex_unlock(&records_list_lock);
	197	if (rc)
	198	return rc;
	199
a61072aa KC	200	mutex_lock(&record->psi->read_mutex);
	201	record->psi->erase(record);
	202	mutex_unlock(&record->psi->read_mutex);
ca01d6dd TL	203
	204	return simple_unlink(dir, dentry);
	205	}
	206
a872d510 TL	207	static void pstore_evict_inode(struct inode *inode)
a872d510 TL	208	{
6dda9266	209	struct pstore_private *p = inode->i_private;
6dda9266	210
dbd5768f	211	clear_inode(inode);
7a0ad546	212	free_pstore_private(p);
a872d510 TL	213	}
a872d510 TL	214
ca01d6dd TL	215	static const struct inode_operations pstore_dir_inode_operations = {
	216	.lookup = simple_lookup,
	217	.unlink = pstore_unlink,
	218	};
	219
22a71c30	220	static struct inode pstore_get_inode(struct super_block sb)
fbe0aa1f TL	221	{
fbe0aa1f TL	222	struct inode *inode = new_inode(sb);
fbe0aa1f TL	223	if (inode) {
fbe0aa1f TL	224	inode->i_ino = get_next_ino();
078cd827	225	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
fbe0aa1f TL	226	}
	227	return inode;
	228	}
	229
366f7e7a LT	230	enum {
	231	Opt_kmsg_bytes, Opt_err
	232	};
	233
	234	static const match_table_t tokens = {
	235	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
	236	{Opt_err, NULL}
	237	};
	238
	239	static void parse_options(char *options)
	240	{
	241	char *p;
	242	substring_t args[MAX_OPT_ARGS];
	243	int option;
	244
	245	if (!options)
	246	return;
	247
	248	while ((p = strsep(&options, ",")) != NULL) {
	249	int token;
	250
	251	if (!*p)
	252	continue;
	253
	254	token = match_token(p, tokens, args);
	255	switch (token) {
	256	case Opt_kmsg_bytes:
	257	if (!match_int(&args[0], &option))
	258	pstore_set_kmsg_bytes(option);
	259	break;
	260	}
	261	}
	262	}
	263
349d7438 DH	264	/*
	265	* Display the mount options in /proc/mounts.
	266	*/
	267	static int pstore_show_options(struct seq_file m, struct dentry root)
	268	{
26fecbf7	269	if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
349d7438 DH	270	seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
	271	return 0;
	272	}
	273
366f7e7a LT	274	static int pstore_remount(struct super_block sb, int flags, char *data)
366f7e7a LT	275	{
02b9984d	276	sync_filesystem(sb);
366f7e7a LT	277	parse_options(data);
	278
	279	return 0;
	280	}
	281
ca01d6dd TL	282	static const struct super_operations pstore_ops = {
	283	.statfs = simple_statfs,
	284	.drop_inode = generic_delete_inode,
a872d510	285	.evict_inode = pstore_evict_inode,
366f7e7a	286	.remount_fs = pstore_remount,
349d7438	287	.show_options = pstore_show_options,
ca01d6dd TL	288	};
ca01d6dd TL	289
27e5041a	290	static struct dentry *psinfo_lock_root(void)
ca01d6dd	291	{
27e5041a KC	292	struct dentry *root;
	293
	294	mutex_lock(&pstore_sb_lock);
	295	/*
	296	* Having no backend is fine -- no records appear.
	297	* Not being mounted is fine -- nothing to do.
	298	*/
	299	if (!psinfo \|\| !pstore_sb) {
	300	mutex_unlock(&pstore_sb_lock);
	301	return NULL;
	302	}
	303
	304	root = pstore_sb->s_root;
	305	inode_lock(d_inode(root));
	306	mutex_unlock(&pstore_sb_lock);
	307
	308	return root;
ca01d6dd TL	309	}
ca01d6dd TL	310
609e28bb KC	311	int pstore_put_backend_records(struct pstore_info *psi)
	312	{
	313	struct pstore_private pos, tmp;
	314	struct dentry *root;
	315	int rc = 0;
	316
	317	root = psinfo_lock_root();
	318	if (!root)
	319	return 0;
	320
	321	mutex_lock(&records_list_lock);
	322	list_for_each_entry_safe(pos, tmp, &records_list, list) {
	323	if (pos->record->psi == psi) {
	324	list_del_init(&pos->list);
	325	rc = simple_unlink(d_inode(root), pos->dentry);
	326	if (WARN_ON(rc))
	327	break;
	328	d_drop(pos->dentry);
	329	dput(pos->dentry);
	330	pos->dentry = NULL;
	331	}
	332	}
	333	mutex_unlock(&records_list_lock);
	334
	335	inode_unlock(d_inode(root));
	336
	337	return rc;
	338	}
	339
ca01d6dd TL	340	/*
	341	* Make a regular file in the root directory of our file system.
	342	* Load it up with "size" bytes of data from "buf".
	343	* Set the mtime & ctime to the date that this record was originally stored.
	344	*/
3a7d2fd1	345	int pstore_mkfile(struct dentry root, struct pstore_record record)
ca01d6dd	346	{
ca01d6dd TL	347	struct dentry *dentry;
ca01d6dd TL	348	struct inode *inode;
6dda9266	349	int rc = 0;
ca01d6dd	350	char name[PSTORE_NAMELEN];
6dda9266	351	struct pstore_private private, pos;
1edd1aa3	352	size_t size = record->size + record->ecc_notice_size;
6dda9266	353
27e5041a KC	354	if (WARN_ON(!inode_is_locked(d_inode(root))))
27e5041a KC	355	return -EINVAL;
3a7d2fd1	356
27e5041a KC	357	rc = -EEXIST;
27e5041a KC	358	/* Skip records that are already present in the filesystem. */
db23491c	359	mutex_lock(&records_list_lock);
47af61ff	360	list_for_each_entry(pos, &records_list, list) {
83f70f07 KC	361	if (pos->record->type == record->type &&
83f70f07 KC	362	pos->record->id == record->id &&
27e5041a KC	363	pos->record->psi == record->psi)
27e5041a KC	364	goto fail;
6dda9266	365	}
ca01d6dd TL	366
ca01d6dd TL	367	rc = -ENOMEM;
3a7d2fd1	368	inode = pstore_get_inode(root->d_sb);
ca01d6dd TL	369	if (!inode)
ca01d6dd TL	370	goto fail;
22a71c30 AV	371	inode->i_mode = S_IFREG \| 0444;
22a71c30 AV	372	inode->i_fop = &pstore_file_operations;
f0f23e54 JFG	373	scnprintf(name, sizeof(name), "%s-%s-%llu%s",
	374	pstore_type_to_name(record->type),
	375	record->psi->name, record->id,
	376	record->compressed ? ".enc.z" : "");
ca01d6dd	377
4c6d80e1 NM	378	private = kzalloc(sizeof(*private), GFP_KERNEL);
	379	if (!private)
	380	goto fail_inode;
	381
ca01d6dd	382	dentry = d_alloc_name(root, name);
c39524e6	383	if (!dentry)
3a7d2fd1	384	goto fail_private;
ca01d6dd	385
609e28bb	386	private->dentry = dentry;
4c6d80e1	387	private->record = record;
83f70f07	388	inode->i_size = private->total_size = size;
ca01d6dd TL	389	inode->i_private = private;
ca01d6dd TL	390
1edd1aa3 KC	391	if (record->time.tv_sec)
1edd1aa3 KC	392	inode->i_mtime = inode->i_ctime = record->time;
ca01d6dd	393
fbe0aa1f	394	d_add(dentry, inode);
ca01d6dd	395
47af61ff	396	list_add(&private->list, &records_list);
db23491c	397	mutex_unlock(&records_list_lock);
6dda9266	398
fbe0aa1f	399	return 0;
ca01d6dd	400
3a7d2fd1	401	fail_private:
1dfff7dd	402	free_pstore_private(private);
4c6d80e1	403	fail_inode:
ca01d6dd	404	iput(inode);
ca01d6dd	405	fail:
27e5041a	406	mutex_unlock(&records_list_lock);
ca01d6dd TL	407	return rc;
	408	}
	409
3a7d2fd1 KC	410	/*
	411	* Read all the records from the persistent store. Create
	412	* files in our filesystem. Don't warn about -EEXIST errors
	413	* when we are re-scanning the backing store looking to add new
	414	* error records.
	415	*/
	416	void pstore_get_records(int quiet)
	417	{
3a7d2fd1 KC	418	struct dentry *root;
3a7d2fd1 KC	419
27e5041a KC	420	root = psinfo_lock_root();
27e5041a KC	421	if (!root)
3a7d2fd1 KC	422	return;
3a7d2fd1 KC	423
27e5041a	424	pstore_get_backend_records(psinfo, root, quiet);
3a7d2fd1 KC	425	inode_unlock(d_inode(root));
	426	}
	427
364ed2f4	428	static int pstore_fill_super(struct super_block sb, void data, int silent)
ca01d6dd	429	{
318ceed0	430	struct inode *inode;
ca01d6dd	431
ca01d6dd	432	sb->s_maxbytes = MAX_LFS_FILESIZE;
09cbfeaf KS	433	sb->s_blocksize = PAGE_SIZE;
09cbfeaf KS	434	sb->s_blocksize_bits = PAGE_SHIFT;
ca01d6dd TL	435	sb->s_magic = PSTOREFS_MAGIC;
	436	sb->s_op = &pstore_ops;
	437	sb->s_time_gran = 1;
	438
366f7e7a LT	439	parse_options(data);
366f7e7a LT	440
22a71c30	441	inode = pstore_get_inode(sb);
318ceed0	442	if (inode) {
d7caa336	443	inode->i_mode = S_IFDIR \| 0750;
318ceed0	444	inode->i_op = &pstore_dir_inode_operations;
22a71c30 AV	445	inode->i_fop = &simple_dir_operations;
22a71c30 AV	446	inc_nlink(inode);
ca01d6dd	447	}
318ceed0 AV	448	sb->s_root = d_make_root(inode);
	449	if (!sb->s_root)
	450	return -ENOMEM;
ca01d6dd	451
27e5041a KC	452	mutex_lock(&pstore_sb_lock);
	453	pstore_sb = sb;
	454	mutex_unlock(&pstore_sb_lock);
	455
6dda9266	456	pstore_get_records(0);
ca01d6dd TL	457
ca01d6dd TL	458	return 0;
ca01d6dd TL	459	}
ca01d6dd TL	460
fbe0aa1f TL	461	static struct dentry pstore_mount(struct file_system_type fs_type,
fbe0aa1f TL	462	int flags, const char dev_name, void data)
ca01d6dd	463	{
fbe0aa1f	464	return mount_single(fs_type, flags, data, pstore_fill_super);
ca01d6dd TL	465	}
	466
	467	static void pstore_kill_sb(struct super_block *sb)
	468	{
27e5041a	469	mutex_lock(&pstore_sb_lock);
9c7d83ae	470	WARN_ON(pstore_sb && pstore_sb != sb);
27e5041a	471
ca01d6dd TL	472	kill_litter_super(sb);
ca01d6dd TL	473	pstore_sb = NULL;
27e5041a KC	474
27e5041a KC	475	mutex_lock(&records_list_lock);
7a0ad546	476	INIT_LIST_HEAD(&records_list);
27e5041a KC	477	mutex_unlock(&records_list_lock);
	478
	479	mutex_unlock(&pstore_sb_lock);
ca01d6dd TL	480	}
	481
	482	static struct file_system_type pstore_fs_type = {
ee1d2674	483	.owner = THIS_MODULE,
ca01d6dd	484	.name = "pstore",
fbe0aa1f	485	.mount = pstore_mount,
ca01d6dd TL	486	.kill_sb = pstore_kill_sb,
	487	};
	488
cb095afd	489	int __init pstore_init_fs(void)
ca01d6dd	490	{
f9bb4882	491	int err;
fb0af3f2 JB	492
fb0af3f2 JB	493	/* Create a convenient mount point for people to access pstore */
f9bb4882 EB	494	err = sysfs_create_mount_point(fs_kobj, "pstore");
f9bb4882 EB	495	if (err)
fb0af3f2	496	goto out;
fb0af3f2 JB	497
	498	err = register_filesystem(&pstore_fs_type);
	499	if (err < 0)
f9bb4882	500	sysfs_remove_mount_point(fs_kobj, "pstore");
fb0af3f2 JB	501
	502	out:
	503	return err;
ca01d6dd	504	}
ca01d6dd	505
cb095afd	506	void __exit pstore_exit_fs(void)
ee1d2674 GT	507	{
	508	unregister_filesystem(&pstore_fs_type);
	509	sysfs_remove_mount_point(fs_kobj, "pstore");
	510	}