WSL2-Linux-Kernel/fs/pstore/inode.c

497 строки
11 KiB
C

/*
* 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/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 <linux/syslog.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_info *psi;
enum pstore_type_id type;
u64 id;
int count;
ssize_t size;
char data[];
};
struct pstore_ftrace_seq_data {
const void *ptr;
size_t off;
size_t size;
};
#define REC_SIZE sizeof(struct pstore_ftrace_record)
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->size % REC_SIZE;
data->off += *pos * REC_SIZE;
if (data->off + REC_SIZE > ps->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;
data->off += REC_SIZE;
if (data->off + REC_SIZE > ps->size)
return NULL;
(*pos)++;
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 = (void *)(ps->data + data->off);
seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %pf <- %pF\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 int pstore_check_syslog_permissions(struct pstore_private *ps)
{
switch (ps->type) {
case PSTORE_TYPE_DMESG:
case PSTORE_TYPE_CONSOLE:
return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
SYSLOG_FROM_READER);
default:
return 0;
}
}
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->type == PSTORE_TYPE_FTRACE)
return seq_read(file, userbuf, count, ppos);
return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->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;
err = pstore_check_syslog_permissions(ps);
if (err)
return err;
if (ps->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;
int err;
err = pstore_check_syslog_permissions(p);
if (err)
return err;
if (p->psi->erase) {
mutex_lock(&p->psi->read_mutex);
p->psi->erase(p->type, p->id, p->count,
d_inode(dentry)->i_ctime, p->psi);
mutex_unlock(&p->psi->read_mutex);
} else {
return -EPERM;
}
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);
kfree(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;
}
}
}
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 = generic_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(enum pstore_type_id type, char *psname, u64 id, int count,
char *data, bool compressed, size_t size,
struct timespec time, struct pstore_info *psi)
{
struct dentry *root = pstore_sb->s_root;
struct dentry *dentry;
struct inode *inode;
int rc = 0;
char name[PSTORE_NAMELEN];
struct pstore_private *private, *pos;
unsigned long flags;
spin_lock_irqsave(&allpstore_lock, flags);
list_for_each_entry(pos, &allpstore, list) {
if (pos->type == type &&
pos->id == id &&
pos->psi == psi) {
rc = -EEXIST;
break;
}
}
spin_unlock_irqrestore(&allpstore_lock, flags);
if (rc)
return rc;
rc = -ENOMEM;
inode = pstore_get_inode(pstore_sb);
if (!inode)
goto fail;
inode->i_mode = S_IFREG | 0444;
inode->i_fop = &pstore_file_operations;
private = kmalloc(sizeof *private + size, GFP_KERNEL);
if (!private)
goto fail_alloc;
private->type = type;
private->id = id;
private->count = count;
private->psi = psi;
switch (type) {
case PSTORE_TYPE_DMESG:
scnprintf(name, sizeof(name), "dmesg-%s-%lld%s",
psname, id, compressed ? ".enc.z" : "");
break;
case PSTORE_TYPE_CONSOLE:
scnprintf(name, sizeof(name), "console-%s-%lld", psname, id);
break;
case PSTORE_TYPE_FTRACE:
scnprintf(name, sizeof(name), "ftrace-%s-%lld", psname, id);
break;
case PSTORE_TYPE_MCE:
scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
break;
case PSTORE_TYPE_PPC_RTAS:
scnprintf(name, sizeof(name), "rtas-%s-%lld", psname, id);
break;
case PSTORE_TYPE_PPC_OF:
scnprintf(name, sizeof(name), "powerpc-ofw-%s-%lld",
psname, id);
break;
case PSTORE_TYPE_PPC_COMMON:
scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
psname, id);
break;
case PSTORE_TYPE_PMSG:
scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
break;
case PSTORE_TYPE_PPC_OPAL:
sprintf(name, "powerpc-opal-%s-%lld", psname, id);
break;
case PSTORE_TYPE_UNKNOWN:
scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
break;
default:
scnprintf(name, sizeof(name), "type%d-%s-%lld",
type, psname, id);
break;
}
inode_lock(d_inode(root));
dentry = d_alloc_name(root, name);
if (!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);
spin_lock_irqsave(&allpstore_lock, flags);
list_add(&private->list, &allpstore);
spin_unlock_irqrestore(&allpstore_lock, flags);
inode_unlock(d_inode(root));
return 0;
fail_lockedalloc:
inode_unlock(d_inode(root));
kfree(private);
fail_alloc:
iput(inode);
fail:
return rc;
}
static int pstore_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode;
save_mount_options(sb, data);
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 | 0755;
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,
};
static int __init init_pstore_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;
}
module_init(init_pstore_fs)
static void __exit exit_pstore_fs(void)
{
unregister_filesystem(&pstore_fs_type);
sysfs_remove_mount_point(fs_kobj, "pstore");
}
module_exit(exit_pstore_fs)
MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
MODULE_LICENSE("GPL");