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511 lines
11 KiB
511 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Persistent Storage - ramfs parts. |
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* |
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* Copyright (C) 2010 Intel Corporation <[email protected]> |
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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/uaccess.h> |
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#include "internal.h" |
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#define PSTORE_NAMELEN 64 |
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static DEFINE_MUTEX(records_list_lock); |
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static LIST_HEAD(records_list); |
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static DEFINE_MUTEX(pstore_sb_lock); |
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static struct super_block *pstore_sb; |
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struct pstore_private { |
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struct list_head list; |
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struct dentry *dentry; |
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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->priv); |
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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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(*pos)++; |
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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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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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if (!data) |
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return 0; |
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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 %ps <- %pS\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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int rc = 0; |
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if (!record->psi->erase) |
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return -EPERM; |
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/* Make sure we can't race while removing this file. */ |
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mutex_lock(&records_list_lock); |
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if (!list_empty(&p->list)) |
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list_del_init(&p->list); |
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else |
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rc = -ENOENT; |
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p->dentry = NULL; |
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mutex_unlock(&records_list_lock); |
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if (rc) |
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return rc; |
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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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clear_inode(inode); |
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free_pstore_private(p); |
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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 != CONFIG_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 dentry *psinfo_lock_root(void) |
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{ |
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struct dentry *root; |
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mutex_lock(&pstore_sb_lock); |
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/* |
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* Having no backend is fine -- no records appear. |
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* Not being mounted is fine -- nothing to do. |
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*/ |
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if (!psinfo || !pstore_sb) { |
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mutex_unlock(&pstore_sb_lock); |
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return NULL; |
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} |
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root = pstore_sb->s_root; |
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inode_lock(d_inode(root)); |
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mutex_unlock(&pstore_sb_lock); |
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return root; |
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} |
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int pstore_put_backend_records(struct pstore_info *psi) |
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{ |
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struct pstore_private *pos, *tmp; |
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struct dentry *root; |
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int rc = 0; |
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root = psinfo_lock_root(); |
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if (!root) |
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return 0; |
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mutex_lock(&records_list_lock); |
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list_for_each_entry_safe(pos, tmp, &records_list, list) { |
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if (pos->record->psi == psi) { |
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list_del_init(&pos->list); |
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rc = simple_unlink(d_inode(root), pos->dentry); |
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if (WARN_ON(rc)) |
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break; |
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d_drop(pos->dentry); |
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dput(pos->dentry); |
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pos->dentry = NULL; |
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} |
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} |
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mutex_unlock(&records_list_lock); |
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inode_unlock(d_inode(root)); |
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return rc; |
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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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size_t size = record->size + record->ecc_notice_size; |
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if (WARN_ON(!inode_is_locked(d_inode(root)))) |
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return -EINVAL; |
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rc = -EEXIST; |
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/* Skip records that are already present in the filesystem. */ |
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mutex_lock(&records_list_lock); |
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list_for_each_entry(pos, &records_list, 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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goto fail; |
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} |
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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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scnprintf(name, sizeof(name), "%s-%s-%llu%s", |
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pstore_type_to_name(record->type), |
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record->psi->name, record->id, |
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record->compressed ? ".enc.z" : ""); |
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private = kzalloc(sizeof(*private), GFP_KERNEL); |
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if (!private) |
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goto fail_inode; |
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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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private->dentry = dentry; |
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private->record = record; |
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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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list_add(&private->list, &records_list); |
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mutex_unlock(&records_list_lock); |
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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_inode: |
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iput(inode); |
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fail: |
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mutex_unlock(&records_list_lock); |
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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 dentry *root; |
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root = psinfo_lock_root(); |
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if (!root) |
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return; |
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pstore_get_backend_records(psinfo, 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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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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mutex_lock(&pstore_sb_lock); |
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pstore_sb = sb; |
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mutex_unlock(&pstore_sb_lock); |
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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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mutex_lock(&pstore_sb_lock); |
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WARN_ON(pstore_sb && pstore_sb != sb); |
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kill_litter_super(sb); |
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pstore_sb = NULL; |
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mutex_lock(&records_list_lock); |
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INIT_LIST_HEAD(&records_list); |
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mutex_unlock(&records_list_lock); |
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mutex_unlock(&pstore_sb_lock); |
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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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int __init pstore_init_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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void __exit pstore_exit_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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