/*
* Persistent Storage - ramfs parts.
*
* Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#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/string.h>
#include <linux/mount.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
struct pstore_private {
u64 id;
int (*erase)(u64);
ssize_t size;
char data[];
};
static int pstore_file_open(struct inode *inode, struct file *file)
{
file->private_data = inode->i_private;
return 0;
}
static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
size_t count, loff_t *ppos)
{
struct pstore_private *ps = file->private_data;
return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
}
static const struct file_operations pstore_file_operations = {
.open = pstore_file_open,
.read = pstore_file_read,
.llseek = default_llseek,
};
/*
* 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 = dentry->d_inode->i_private;
p->erase(p->id);
return simple_unlink(dir, dentry);
}
static void pstore_evict_inode(struct inode *inode)
{
end_writeback(inode);
kfree(inode->i_private);
}
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,
const struct inode *dir, int mode, dev_t dev)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode->i_uid = inode->i_gid = 0;
inode->i_mode = mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
switch (mode & S_IFMT) {
case S_IFREG:
inode->i_fop = &pstore_file_operations;
break;
case S_IFDIR:
inode->i_op = &pstore_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inc_nlink(inode);
break;
}
}
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;
}
}
}
static int pstore_remount(struct super_block *sb, int *flags, char *data)
{
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 = generic_show_options,
};
static struct super_block *pstore_sb;
int 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(enum pstore_type_id type, char *psname, u64 id,
char *data, size_t size,
struct timespec time, int (*erase)(u64))
{
struct dentry *root = pstore_sb->s_root;
struct dentry *dentry;
struct inode *inode;
int rc;
char name[PSTORE_NAMELEN];
struct pstore_private *private;
rc = -ENOMEM;
inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
if (!inode)
goto fail;
private = kmalloc(sizeof *private + size, GFP_KERNEL);
if (!private)
goto fail_alloc;
private->id = id;
private->erase = erase;
switch (type) {
case PSTORE_TYPE_DMESG:
sprintf(name, "dmesg-%s-%lld", psname, id);
break;
case PSTORE_TYPE_MCE:
sprintf(name, "mce-%s-%lld", psname, id);
break;
case PSTORE_TYPE_UNKNOWN:
sprintf(name, "unknown-%s-%lld", psname, id);
break;
default:
sprintf(name, "type%d-%s-%lld", type, psname, id);
break;
}
mutex_lock(&root->d_inode->i_mutex);
rc = -ENOSPC;
dentry = d_alloc_name(root, name);
if (IS_ERR(dentry))
goto fail_lockedalloc;
memcpy(private->data, data, size);
inode->i_size = private->size = size;
inode->i_private = private;
if (time.tv_sec)
inode->i_mtime = inode->i_ctime = time;
d_add(dentry, inode);
mutex_unlock(&root->d_inode->i_mutex);
return 0;
fail_lockedalloc:
mutex_unlock(&root->d_inode->i_mutex);
kfree(private);
fail_alloc:
iput(inode);
fail:
return rc;
}
int pstore_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode = NULL;
struct dentry *root;
int err;
save_mount_options(sb, data);
pstore_sb = sb;
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = PSTOREFS_MAGIC;
sb->s_op = &pstore_ops;
sb->s_time_gran = 1;
parse_options(data);
inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
if (!inode) {
err = -ENOMEM;
goto fail;
}
/* override ramfs "dir" options so we catch unlink(2) */
inode->i_op = &pstore_dir_inode_operations;
root = d_alloc_root(inode);
sb->s_root = root;
if (!root) {
err = -ENOMEM;
goto fail;
}
pstore_get_records();
return 0;
fail:
iput(inode);
return err;
}
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 = {
.name = "pstore",
.mount = pstore_mount,
.kill_sb = pstore_kill_sb,
};
static int __init init_pstore_fs(void)
{
return register_filesystem(&pstore_fs_type);
}
module_init(init_pstore_fs)
MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
MODULE_LICENSE("GPL");
