Commit ca01d6dd authored by Tony Luck's avatar Tony Luck

pstore: new filesystem interface to platform persistent storage

Some platforms have a small amount of non-volatile storage that
can be used to store information useful to diagnose the cause of
a system crash.  This is the generic part of a file system interface
that presents information from the crash as a series of files in
/dev/pstore.  Once the information has been seen, the underlying
storage is freed by deleting the files.
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 90a8a73c
Where: /dev/pstore/...
Date: January 2011
Kernel Version: 2.6.38
Contact: tony.luck@intel.com
Description: Generic interface to platform dependent persistent storage.
Platforms that provide a mechanism to preserve some data
across system reboots can register with this driver to
provide a generic interface to show records captured in
the dying moments. In the case of a panic the last part
of the console log is captured, but other interesting
data can also be saved.
# mount -t pstore - /dev/pstore
$ ls -l /dev/pstore
total 0
-r--r--r-- 1 root root 7896 Nov 30 15:38 dmesg-erst-1
Different users of this interface will result in different
filename prefixes. Currently two are defined:
"dmesg" - saved console log
"mce" - architecture dependent data from fatal h/w error
Once the information in a file has been read, removing
the file will signal to the underlying persistent storage
device that it can reclaim the space for later re-use.
$ rm /dev/pstore/dmesg-erst-1
The expectation is that all files in /dev/pstore
will be saved elsewhere and erased from persistent store
soon after boot to free up space ready for the next
catastrophe.
What: /sys/fs/pstore/kmsg_bytes
Date: January 2011
Kernel Version: 2.6.38
Contact: "Tony Luck" <tony.luck@intel.com>
Description:
Controls amount of console log that will be saved
to persistent store on oops/panic.
......@@ -188,6 +188,7 @@ source "fs/omfs/Kconfig"
source "fs/hpfs/Kconfig"
source "fs/qnx4/Kconfig"
source "fs/romfs/Kconfig"
source "fs/pstore/Kconfig"
source "fs/sysv/Kconfig"
source "fs/ufs/Kconfig"
source "fs/exofs/Kconfig"
......
......@@ -121,3 +121,4 @@ obj-$(CONFIG_BTRFS_FS) += btrfs/
obj-$(CONFIG_GFS2_FS) += gfs2/
obj-$(CONFIG_EXOFS_FS) += exofs/
obj-$(CONFIG_CEPH_FS) += ceph/
obj-$(CONFIG_PSTORE) += pstore/
config PSTORE
bool "Persistant store support"
default n
help
This option enables generic access to platform level
persistent storage via "pstore" filesystem that can
be mounted as /dev/pstore. Only useful if you have
a platform level driver that registers with pstore to
provide the data, so you probably should just go say "Y"
(or "M") to a platform specific persistent store driver
(e.g. ACPI_APEI on X86) which will select this for you.
If you don't have a platform persistent store driver,
say N.
#
# Makefile for the linux pstorefs routines.
#
obj-y += pstore.o
pstore-objs += inode.o platform.o
/*
* 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 ret = 0;
struct kobject *pstorefs_kobj;
pstorefs_kobj = kobject_create_and_add("pstore", fs_kobj);
if (!pstorefs_kobj)
return -ENOMEM;
sysfs_create_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
ret = register_filesystem(&pstore_fs_type);
if (ret) {
sysfs_remove_file(pstorefs_kobj, &pstore_kmsg_bytes_attr.attr);
kobject_put(pstorefs_kobj);
}
return ret;
}
module_init(init_pstore_fs)
MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
MODULE_LICENSE("GPL");
extern void pstore_get_records(void);
extern int pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
char *data, size_t size,
struct timespec time, int (*erase)(u64));
extern int pstore_is_mounted(void);
extern struct kobj_attribute pstore_kmsg_bytes_attr;
/*
* Persistent Storage - platform driver interface 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/atomic.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kmsg_dump.h>
#include <linux/module.h>
#include <linux/pstore.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include "internal.h"
/*
* pstore_lock just protects "psinfo" during
* calls to pstore_register()
*/
static DEFINE_SPINLOCK(pstore_lock);
static struct pstore_info *psinfo;
/* How much of the console log to snapshot. /sys/fs/pstore/kmsg_bytes */
static unsigned long kmsg_bytes = 10240;
static ssize_t b_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%lu\n", kmsg_bytes);
}
static ssize_t b_store(struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t count)
{
return (sscanf(buf, "%lu", &kmsg_bytes) > 0) ? count : 0;
}
struct kobj_attribute pstore_kmsg_bytes_attr =
__ATTR(kmsg_bytes, S_IRUGO | S_IWUSR, b_show, b_store);
/* Tag each group of saved records with a sequence number */
static int oopscount;
/*
* callback from kmsg_dump. (s2,l2) has the most recently
* written bytes, older bytes are in (s1,l1). Save as much
* as we can from the end of the buffer.
*/
static void pstore_dump(struct kmsg_dumper *dumper,
enum kmsg_dump_reason reason,
const char *s1, unsigned long l1,
const char *s2, unsigned long l2)
{
unsigned long s1_start, s2_start;
unsigned long l1_cpy, l2_cpy;
unsigned long size, total = 0;
char *dst;
u64 id;
int hsize, part = 1;
mutex_lock(&psinfo->buf_mutex);
oopscount++;
while (total < kmsg_bytes) {
dst = psinfo->buf;
hsize = sprintf(dst, "Oops#%d Part%d\n", oopscount, part++);
size = psinfo->bufsize - hsize;
dst += hsize;
l2_cpy = min(l2, size);
l1_cpy = min(l1, size - l2_cpy);
if (l1_cpy + l2_cpy == 0)
break;
s2_start = l2 - l2_cpy;
s1_start = l1 - l1_cpy;
memcpy(dst, s1 + s1_start, l1_cpy);
memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
id = psinfo->write(PSTORE_TYPE_DMESG, hsize + l1_cpy + l2_cpy);
if (pstore_is_mounted())
pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id,
psinfo->buf, hsize + l1_cpy + l2_cpy,
CURRENT_TIME, psinfo->erase);
l1 -= l1_cpy;
l2 -= l2_cpy;
total += l1_cpy + l2_cpy;
}
mutex_unlock(&psinfo->buf_mutex);
}
static struct kmsg_dumper pstore_dumper = {
.dump = pstore_dump,
};
/*
* platform specific persistent storage driver registers with
* us here. If pstore is already mounted, call the platform
* read function right away to populate the file system. If not
* then the pstore mount code will call us later to fill out
* the file system.
*
* Register with kmsg_dump to save last part of console log on panic.
*/
int pstore_register(struct pstore_info *psi)
{
struct module *owner = psi->owner;
spin_lock(&pstore_lock);
if (psinfo) {
spin_unlock(&pstore_lock);
return -EBUSY;
}
psinfo = psi;
spin_unlock(&pstore_lock);
if (owner && !try_module_get(owner)) {
psinfo = NULL;
return -EINVAL;
}
if (pstore_is_mounted())
pstore_get_records();
kmsg_dump_register(&pstore_dumper);
return 0;
}
EXPORT_SYMBOL_GPL(pstore_register);
/*
* Read all the records from the persistent store. Create and
* file files in our filesystem.
*/
void pstore_get_records(void)
{
struct pstore_info *psi = psinfo;
size_t size;
u64 id;
enum pstore_type_id type;
struct timespec time;
int failed = 0;
if (!psi)
return;
mutex_lock(&psinfo->buf_mutex);
while ((size = psi->read(&id, &type, &time)) > 0) {
if (pstore_mkfile(type, psi->name, id, psi->buf, size,
time, psi->erase))
failed++;
}
mutex_unlock(&psinfo->buf_mutex);
if (failed)
printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
failed, psi->name);
}
/*
* Call platform driver to write a record to the
* persistent store.
*/
int pstore_write(enum pstore_type_id type, char *buf, size_t size)
{
u64 id;
if (!psinfo)
return -ENODEV;
if (size > psinfo->bufsize)
return -EFBIG;
mutex_lock(&psinfo->buf_mutex);
memcpy(psinfo->buf, buf, size);
id = psinfo->write(type, size);
if (pstore_is_mounted())
pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
size, CURRENT_TIME, psinfo->erase);
mutex_unlock(&psinfo->buf_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(pstore_write);
......@@ -26,6 +26,7 @@
#define ISOFS_SUPER_MAGIC 0x9660
#define JFFS2_SUPER_MAGIC 0x72b6
#define ANON_INODE_FS_MAGIC 0x09041934
#define PSTOREFS_MAGIC 0x6165676C
#define MINIX_SUPER_MAGIC 0x137F /* original minix fs */
#define MINIX_SUPER_MAGIC2 0x138F /* minix fs, 30 char names */
......
/*
* Persistent Storage - pstore.h
*
* Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
*
* This code is the generic layer to export data records from platform
* level persistent storage via a file system.
*
* 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
*/
#ifndef _LINUX_PSTORE_H
#define _LINUX_PSTORE_H
/* types */
enum pstore_type_id {
PSTORE_TYPE_DMESG = 0,
PSTORE_TYPE_MCE = 1,
PSTORE_TYPE_UNKNOWN = 255
};
struct pstore_info {
struct module *owner;
char *name;
struct mutex buf_mutex; /* serialize access to 'buf' */
char *buf;
size_t bufsize;
size_t (*read)(u64 *id, enum pstore_type_id *type,
struct timespec *time);
u64 (*write)(enum pstore_type_id type, size_t size);
int (*erase)(u64 id);
};
#ifdef CONFIG_PSTORE
extern int pstore_register(struct pstore_info *);
extern int pstore_write(enum pstore_type_id type, char *buf, size_t size);
#else
static inline int
pstore_register(struct pstore_info *psi)
{
return -ENODEV;
}
static inline int
pstore_write(enum pstore_type_id type, char *buf, size_t size)
{
return -ENODEV;
}
#endif
#endif /*_LINUX_PSTORE_H*/
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