/*
* 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/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);
};
#define pstore_get_inode ramfs_get_inode
/*
* 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);
kfree(p);
return simple_unlink(dir, dentry);
}
static const struct inode_operations pstore_dir_inode_operations = {
.lookup = simple_lookup,
.unlink = pstore_unlink,
};
static const struct super_operations pstore_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
.show_options = generic_show_options,
};
static struct super_block *pstore_sb;
static struct vfsmount *pstore_mnt;
int pstore_is_mounted(void)
{
return pstore_mnt != NULL;
}
/*
* Set up a file structure as if we had opened this file and
* write our data to it.
*/
static int pstore_writefile(struct inode *inode, struct dentry *dentry,
char *data, size_t size)
{
struct file f;
ssize_t n;
mm_segment_t old_fs = get_fs();
memset(&f, '0', sizeof f);
f.f_mapping = inode->i_mapping;
f.f_path.dentry = dentry;
f.f_path.mnt = pstore_mnt;
f.f_pos = 0;
f.f_op = inode->i_fop;
set_fs(KERNEL_DS);
n = do_sync_write(&f, data, size, &f.f_pos);
set_fs(old_fs);
fsnotify_modify(&f);
return n == size;
}
/*
* 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;
inode->i_uid = inode->i_gid = 0;
private = kmalloc(sizeof *private, 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;
d_add(dentry, inode);
mutex_unlock(&root->d_inode->i_mutex);
if (!pstore_writefile(inode, dentry, data, size))
goto fail_write;
inode->i_private = private;
if (time.tv_sec)
inode->i_mtime = inode->i_ctime = time;
return 0;
fail_write:
kfree(private);
inode->i_nlink--;
mutex_lock(&root->d_inode->i_mutex);
d_delete(dentry);
dput(dentry);
mutex_unlock(&root->d_inode->i_mutex);
goto fail;
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;
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 int pstore_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
struct dentry *root;
root = mount_nodev(fs_type, flags, data, pstore_fill_super);
if (IS_ERR(root))
return -ENOMEM;
mnt->mnt_root = root;
mnt->mnt_sb = root->d_sb;
pstore_mnt = mnt;
return 0;
}
static void pstore_kill_sb(struct super_block *sb)
{
kill_litter_super(sb);
pstore_sb = NULL;
pstore_mnt = NULL;
}
static struct file_system_type pstore_fs_type = {
.name = "pstore",
.get_sb = pstore_get_sb,
.kill_sb = pstore_kill_sb,
};
static int __init init_pstore_fs(void)
{
int rc = 0;
struct kobject *pstorefs_kobj;
pstorefs_kobj = kobject_create_and_add("pstore", fs_kobj);
if (!pstorefs_kobj) {
rc = -ENOMEM;
goto done;
}
rc = sysfs_create_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
if (rc)
goto done1;
rc = register_filesystem(&pstore_fs_type);
if (rc == 0)
goto done;
sysfs_remove_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
done1:
kobject_put(pstorefs_kobj);
done:
return rc;
}
module_init(init_pstore_fs)
MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
MODULE_LICENSE("GPL");
