![Kees Cook](/assets/img/avatar_default.png)
This reverts commit 68c4a4f8ab
, with
various conflict clean-ups.
The capability check required too much privilege compared to simple DAC
controls. A system builder was forced to have crash handler processes
run with CAP_SYSLOG which would give it the ability to read (and wipe)
the _current_ dmesg, which is much more access than being given access
only to the historical log stored in pstorefs.
With the prior commit to make the root directory 0750, the files are
protected by default but a system builder can now opt to give access
to a specific group (via chgrp on the pstorefs root directory) without
being forced to also give away CAP_SYSLOG.
Suggested-by: Nick Kralevich <nnk@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
512 lines
12 KiB
C
512 lines
12 KiB
C
/*
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* Persistent Storage - ramfs parts.
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*
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* Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/fsnotify.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/time.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <linux/string.h>
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#include <linux/mount.h>
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#include <linux/seq_file.h>
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#include <linux/ramfs.h>
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#include <linux/parser.h>
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#include <linux/sched.h>
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#include <linux/magic.h>
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#include <linux/pstore.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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#define PSTORE_NAMELEN 64
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static DEFINE_SPINLOCK(allpstore_lock);
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static LIST_HEAD(allpstore);
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struct pstore_private {
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struct list_head list;
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struct pstore_record *record;
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size_t total_size;
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};
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struct pstore_ftrace_seq_data {
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const void *ptr;
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size_t off;
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size_t size;
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};
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#define REC_SIZE sizeof(struct pstore_ftrace_record)
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static void free_pstore_private(struct pstore_private *private)
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{
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if (!private)
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return;
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if (private->record) {
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kfree(private->record->buf);
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kfree(private->record);
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}
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kfree(private);
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}
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static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
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{
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struct pstore_private *ps = s->private;
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struct pstore_ftrace_seq_data *data;
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data = kzalloc(sizeof(*data), GFP_KERNEL);
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if (!data)
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return NULL;
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data->off = ps->total_size % REC_SIZE;
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data->off += *pos * REC_SIZE;
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if (data->off + REC_SIZE > ps->total_size) {
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kfree(data);
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return NULL;
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}
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return data;
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}
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static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
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{
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kfree(v);
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}
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static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
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{
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struct pstore_private *ps = s->private;
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struct pstore_ftrace_seq_data *data = v;
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data->off += REC_SIZE;
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if (data->off + REC_SIZE > ps->total_size)
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return NULL;
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(*pos)++;
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return data;
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}
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static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
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{
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struct pstore_private *ps = s->private;
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struct pstore_ftrace_seq_data *data = v;
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struct pstore_ftrace_record *rec;
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rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
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seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %pf <- %pF\n",
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pstore_ftrace_decode_cpu(rec),
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pstore_ftrace_read_timestamp(rec),
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rec->ip, rec->parent_ip, (void *)rec->ip,
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(void *)rec->parent_ip);
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return 0;
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}
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static const struct seq_operations pstore_ftrace_seq_ops = {
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.start = pstore_ftrace_seq_start,
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.next = pstore_ftrace_seq_next,
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.stop = pstore_ftrace_seq_stop,
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.show = pstore_ftrace_seq_show,
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};
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static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
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size_t count, loff_t *ppos)
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{
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struct seq_file *sf = file->private_data;
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struct pstore_private *ps = sf->private;
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if (ps->record->type == PSTORE_TYPE_FTRACE)
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return seq_read(file, userbuf, count, ppos);
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return simple_read_from_buffer(userbuf, count, ppos,
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ps->record->buf, ps->total_size);
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}
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static int pstore_file_open(struct inode *inode, struct file *file)
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{
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struct pstore_private *ps = inode->i_private;
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struct seq_file *sf;
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int err;
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const struct seq_operations *sops = NULL;
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if (ps->record->type == PSTORE_TYPE_FTRACE)
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sops = &pstore_ftrace_seq_ops;
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err = seq_open(file, sops);
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if (err < 0)
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return err;
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sf = file->private_data;
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sf->private = ps;
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return 0;
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}
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static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
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{
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struct seq_file *sf = file->private_data;
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if (sf->op)
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return seq_lseek(file, off, whence);
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return default_llseek(file, off, whence);
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}
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static const struct file_operations pstore_file_operations = {
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.open = pstore_file_open,
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.read = pstore_file_read,
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.llseek = pstore_file_llseek,
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.release = seq_release,
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};
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/*
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* When a file is unlinked from our file system we call the
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* platform driver to erase the record from persistent store.
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*/
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static int pstore_unlink(struct inode *dir, struct dentry *dentry)
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{
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struct pstore_private *p = d_inode(dentry)->i_private;
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struct pstore_record *record = p->record;
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if (!record->psi->erase)
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return -EPERM;
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mutex_lock(&record->psi->read_mutex);
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record->psi->erase(record);
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mutex_unlock(&record->psi->read_mutex);
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return simple_unlink(dir, dentry);
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}
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static void pstore_evict_inode(struct inode *inode)
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{
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struct pstore_private *p = inode->i_private;
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unsigned long flags;
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clear_inode(inode);
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if (p) {
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spin_lock_irqsave(&allpstore_lock, flags);
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list_del(&p->list);
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spin_unlock_irqrestore(&allpstore_lock, flags);
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free_pstore_private(p);
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}
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}
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static const struct inode_operations pstore_dir_inode_operations = {
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.lookup = simple_lookup,
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.unlink = pstore_unlink,
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};
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static struct inode *pstore_get_inode(struct super_block *sb)
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{
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struct inode *inode = new_inode(sb);
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if (inode) {
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inode->i_ino = get_next_ino();
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inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
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}
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return inode;
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}
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enum {
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Opt_kmsg_bytes, Opt_err
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};
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static const match_table_t tokens = {
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{Opt_kmsg_bytes, "kmsg_bytes=%u"},
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{Opt_err, NULL}
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};
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static void parse_options(char *options)
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{
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char *p;
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substring_t args[MAX_OPT_ARGS];
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int option;
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if (!options)
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return;
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while ((p = strsep(&options, ",")) != NULL) {
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int token;
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if (!*p)
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continue;
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token = match_token(p, tokens, args);
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switch (token) {
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case Opt_kmsg_bytes:
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if (!match_int(&args[0], &option))
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pstore_set_kmsg_bytes(option);
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break;
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}
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}
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}
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/*
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* Display the mount options in /proc/mounts.
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*/
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static int pstore_show_options(struct seq_file *m, struct dentry *root)
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{
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if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
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seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
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return 0;
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}
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static int pstore_remount(struct super_block *sb, int *flags, char *data)
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{
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sync_filesystem(sb);
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parse_options(data);
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return 0;
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}
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static const struct super_operations pstore_ops = {
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.statfs = simple_statfs,
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.drop_inode = generic_delete_inode,
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.evict_inode = pstore_evict_inode,
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.remount_fs = pstore_remount,
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.show_options = pstore_show_options,
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};
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static struct super_block *pstore_sb;
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bool pstore_is_mounted(void)
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{
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return pstore_sb != NULL;
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}
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/*
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* Make a regular file in the root directory of our file system.
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* Load it up with "size" bytes of data from "buf".
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* Set the mtime & ctime to the date that this record was originally stored.
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*/
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int pstore_mkfile(struct dentry *root, struct pstore_record *record)
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{
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struct dentry *dentry;
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struct inode *inode;
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int rc = 0;
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char name[PSTORE_NAMELEN];
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struct pstore_private *private, *pos;
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unsigned long flags;
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size_t size = record->size + record->ecc_notice_size;
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WARN_ON(!inode_is_locked(d_inode(root)));
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spin_lock_irqsave(&allpstore_lock, flags);
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list_for_each_entry(pos, &allpstore, list) {
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if (pos->record->type == record->type &&
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pos->record->id == record->id &&
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pos->record->psi == record->psi) {
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rc = -EEXIST;
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break;
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}
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}
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spin_unlock_irqrestore(&allpstore_lock, flags);
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if (rc)
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return rc;
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rc = -ENOMEM;
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inode = pstore_get_inode(root->d_sb);
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if (!inode)
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goto fail;
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inode->i_mode = S_IFREG | 0444;
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inode->i_fop = &pstore_file_operations;
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private = kzalloc(sizeof(*private), GFP_KERNEL);
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if (!private)
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goto fail_alloc;
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private->record = record;
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switch (record->type) {
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case PSTORE_TYPE_DMESG:
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scnprintf(name, sizeof(name), "dmesg-%s-%llu%s",
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record->psi->name, record->id,
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record->compressed ? ".enc.z" : "");
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break;
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case PSTORE_TYPE_CONSOLE:
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scnprintf(name, sizeof(name), "console-%s-%llu",
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record->psi->name, record->id);
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break;
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case PSTORE_TYPE_FTRACE:
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scnprintf(name, sizeof(name), "ftrace-%s-%llu",
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record->psi->name, record->id);
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break;
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case PSTORE_TYPE_MCE:
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scnprintf(name, sizeof(name), "mce-%s-%llu",
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record->psi->name, record->id);
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break;
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case PSTORE_TYPE_PPC_RTAS:
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scnprintf(name, sizeof(name), "rtas-%s-%llu",
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record->psi->name, record->id);
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break;
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case PSTORE_TYPE_PPC_OF:
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scnprintf(name, sizeof(name), "powerpc-ofw-%s-%llu",
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record->psi->name, record->id);
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break;
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case PSTORE_TYPE_PPC_COMMON:
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scnprintf(name, sizeof(name), "powerpc-common-%s-%llu",
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record->psi->name, record->id);
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break;
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case PSTORE_TYPE_PMSG:
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scnprintf(name, sizeof(name), "pmsg-%s-%llu",
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record->psi->name, record->id);
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break;
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case PSTORE_TYPE_PPC_OPAL:
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scnprintf(name, sizeof(name), "powerpc-opal-%s-%llu",
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record->psi->name, record->id);
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break;
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case PSTORE_TYPE_UNKNOWN:
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scnprintf(name, sizeof(name), "unknown-%s-%llu",
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record->psi->name, record->id);
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break;
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default:
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scnprintf(name, sizeof(name), "type%d-%s-%llu",
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record->type, record->psi->name, record->id);
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break;
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}
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dentry = d_alloc_name(root, name);
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if (!dentry)
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goto fail_private;
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inode->i_size = private->total_size = size;
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inode->i_private = private;
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if (record->time.tv_sec)
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inode->i_mtime = inode->i_ctime = record->time;
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d_add(dentry, inode);
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spin_lock_irqsave(&allpstore_lock, flags);
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list_add(&private->list, &allpstore);
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spin_unlock_irqrestore(&allpstore_lock, flags);
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return 0;
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fail_private:
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free_pstore_private(private);
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fail_alloc:
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iput(inode);
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fail:
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return rc;
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}
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/*
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* Read all the records from the persistent store. Create
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* files in our filesystem. Don't warn about -EEXIST errors
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* when we are re-scanning the backing store looking to add new
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* error records.
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*/
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void pstore_get_records(int quiet)
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{
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struct pstore_info *psi = psinfo;
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struct dentry *root;
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if (!psi || !pstore_sb)
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return;
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root = pstore_sb->s_root;
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inode_lock(d_inode(root));
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pstore_get_backend_records(psi, root, quiet);
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inode_unlock(d_inode(root));
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}
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static int pstore_fill_super(struct super_block *sb, void *data, int silent)
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{
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struct inode *inode;
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pstore_sb = sb;
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sb->s_maxbytes = MAX_LFS_FILESIZE;
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sb->s_blocksize = PAGE_SIZE;
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sb->s_blocksize_bits = PAGE_SHIFT;
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sb->s_magic = PSTOREFS_MAGIC;
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sb->s_op = &pstore_ops;
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sb->s_time_gran = 1;
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parse_options(data);
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inode = pstore_get_inode(sb);
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if (inode) {
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inode->i_mode = S_IFDIR | 0750;
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inode->i_op = &pstore_dir_inode_operations;
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inode->i_fop = &simple_dir_operations;
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inc_nlink(inode);
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}
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sb->s_root = d_make_root(inode);
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if (!sb->s_root)
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return -ENOMEM;
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pstore_get_records(0);
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return 0;
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}
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static struct dentry *pstore_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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return mount_single(fs_type, flags, data, pstore_fill_super);
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}
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static void pstore_kill_sb(struct super_block *sb)
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{
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kill_litter_super(sb);
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pstore_sb = NULL;
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}
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static struct file_system_type pstore_fs_type = {
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.owner = THIS_MODULE,
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.name = "pstore",
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.mount = pstore_mount,
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.kill_sb = pstore_kill_sb,
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};
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static int __init init_pstore_fs(void)
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{
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int err;
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/* Create a convenient mount point for people to access pstore */
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err = sysfs_create_mount_point(fs_kobj, "pstore");
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if (err)
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goto out;
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err = register_filesystem(&pstore_fs_type);
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if (err < 0)
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sysfs_remove_mount_point(fs_kobj, "pstore");
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out:
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return err;
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}
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module_init(init_pstore_fs)
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static void __exit exit_pstore_fs(void)
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{
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unregister_filesystem(&pstore_fs_type);
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sysfs_remove_mount_point(fs_kobj, "pstore");
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}
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module_exit(exit_pstore_fs)
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MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
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MODULE_LICENSE("GPL");
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