1 // SPDX-License-Identifier: GPL-2.0-only
3 * Persistent Storage - ramfs parts.
5 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
8 #include <linux/module.h>
10 #include <linux/fsnotify.h>
11 #include <linux/pagemap.h>
12 #include <linux/highmem.h>
13 #include <linux/time.h>
14 #include <linux/init.h>
15 #include <linux/list.h>
16 #include <linux/string.h>
17 #include <linux/mount.h>
18 #include <linux/seq_file.h>
19 #include <linux/ramfs.h>
20 #include <linux/parser.h>
21 #include <linux/sched.h>
22 #include <linux/magic.h>
23 #include <linux/pstore.h>
24 #include <linux/slab.h>
25 #include <linux/spinlock.h>
26 #include <linux/uaccess.h>
30 #define PSTORE_NAMELEN 64
32 static DEFINE_SPINLOCK(allpstore_lock);
33 static LIST_HEAD(allpstore);
35 struct pstore_private {
36 struct list_head list;
37 struct pstore_record *record;
41 struct pstore_ftrace_seq_data {
47 #define REC_SIZE sizeof(struct pstore_ftrace_record)
49 static void free_pstore_private(struct pstore_private *private)
53 if (private->record) {
54 kfree(private->record->buf);
55 kfree(private->record);
60 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
62 struct pstore_private *ps = s->private;
63 struct pstore_ftrace_seq_data *data;
65 data = kzalloc(sizeof(*data), GFP_KERNEL);
69 data->off = ps->total_size % REC_SIZE;
70 data->off += *pos * REC_SIZE;
71 if (data->off + REC_SIZE > ps->total_size) {
80 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
85 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
87 struct pstore_private *ps = s->private;
88 struct pstore_ftrace_seq_data *data = v;
91 data->off += REC_SIZE;
92 if (data->off + REC_SIZE > ps->total_size)
98 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
100 struct pstore_private *ps = s->private;
101 struct pstore_ftrace_seq_data *data = v;
102 struct pstore_ftrace_record *rec;
107 rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
109 seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %ps <- %pS\n",
110 pstore_ftrace_decode_cpu(rec),
111 pstore_ftrace_read_timestamp(rec),
112 rec->ip, rec->parent_ip, (void *)rec->ip,
113 (void *)rec->parent_ip);
118 static const struct seq_operations pstore_ftrace_seq_ops = {
119 .start = pstore_ftrace_seq_start,
120 .next = pstore_ftrace_seq_next,
121 .stop = pstore_ftrace_seq_stop,
122 .show = pstore_ftrace_seq_show,
125 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
126 size_t count, loff_t *ppos)
128 struct seq_file *sf = file->private_data;
129 struct pstore_private *ps = sf->private;
131 if (ps->record->type == PSTORE_TYPE_FTRACE)
132 return seq_read(file, userbuf, count, ppos);
133 return simple_read_from_buffer(userbuf, count, ppos,
134 ps->record->buf, ps->total_size);
137 static int pstore_file_open(struct inode *inode, struct file *file)
139 struct pstore_private *ps = inode->i_private;
142 const struct seq_operations *sops = NULL;
144 if (ps->record->type == PSTORE_TYPE_FTRACE)
145 sops = &pstore_ftrace_seq_ops;
147 err = seq_open(file, sops);
151 sf = file->private_data;
157 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
159 struct seq_file *sf = file->private_data;
162 return seq_lseek(file, off, whence);
163 return default_llseek(file, off, whence);
166 static const struct file_operations pstore_file_operations = {
167 .open = pstore_file_open,
168 .read = pstore_file_read,
169 .llseek = pstore_file_llseek,
170 .release = seq_release,
174 * When a file is unlinked from our file system we call the
175 * platform driver to erase the record from persistent store.
177 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
179 struct pstore_private *p = d_inode(dentry)->i_private;
180 struct pstore_record *record = p->record;
182 if (!record->psi->erase)
185 mutex_lock(&record->psi->read_mutex);
186 record->psi->erase(record);
187 mutex_unlock(&record->psi->read_mutex);
189 return simple_unlink(dir, dentry);
192 static void pstore_evict_inode(struct inode *inode)
194 struct pstore_private *p = inode->i_private;
199 spin_lock_irqsave(&allpstore_lock, flags);
201 spin_unlock_irqrestore(&allpstore_lock, flags);
202 free_pstore_private(p);
206 static const struct inode_operations pstore_dir_inode_operations = {
207 .lookup = simple_lookup,
208 .unlink = pstore_unlink,
211 static struct inode *pstore_get_inode(struct super_block *sb)
213 struct inode *inode = new_inode(sb);
215 inode->i_ino = get_next_ino();
216 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
222 Opt_kmsg_bytes, Opt_err
225 static const match_table_t tokens = {
226 {Opt_kmsg_bytes, "kmsg_bytes=%u"},
230 static void parse_options(char *options)
233 substring_t args[MAX_OPT_ARGS];
239 while ((p = strsep(&options, ",")) != NULL) {
245 token = match_token(p, tokens, args);
248 if (!match_int(&args[0], &option))
249 pstore_set_kmsg_bytes(option);
256 * Display the mount options in /proc/mounts.
258 static int pstore_show_options(struct seq_file *m, struct dentry *root)
260 if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
261 seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
265 static int pstore_remount(struct super_block *sb, int *flags, char *data)
273 static const struct super_operations pstore_ops = {
274 .statfs = simple_statfs,
275 .drop_inode = generic_delete_inode,
276 .evict_inode = pstore_evict_inode,
277 .remount_fs = pstore_remount,
278 .show_options = pstore_show_options,
281 static struct super_block *pstore_sb;
283 bool pstore_is_mounted(void)
285 return pstore_sb != NULL;
289 * Make a regular file in the root directory of our file system.
290 * Load it up with "size" bytes of data from "buf".
291 * Set the mtime & ctime to the date that this record was originally stored.
293 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
295 struct dentry *dentry;
298 char name[PSTORE_NAMELEN];
299 struct pstore_private *private, *pos;
301 size_t size = record->size + record->ecc_notice_size;
303 WARN_ON(!inode_is_locked(d_inode(root)));
305 spin_lock_irqsave(&allpstore_lock, flags);
306 list_for_each_entry(pos, &allpstore, list) {
307 if (pos->record->type == record->type &&
308 pos->record->id == record->id &&
309 pos->record->psi == record->psi) {
314 spin_unlock_irqrestore(&allpstore_lock, flags);
319 inode = pstore_get_inode(root->d_sb);
322 inode->i_mode = S_IFREG | 0444;
323 inode->i_fop = &pstore_file_operations;
324 scnprintf(name, sizeof(name), "%s-%s-%llu%s",
325 pstore_type_to_name(record->type),
326 record->psi->name, record->id,
327 record->compressed ? ".enc.z" : "");
329 private = kzalloc(sizeof(*private), GFP_KERNEL);
333 dentry = d_alloc_name(root, name);
337 private->record = record;
338 inode->i_size = private->total_size = size;
339 inode->i_private = private;
341 if (record->time.tv_sec)
342 inode->i_mtime = inode->i_ctime = record->time;
344 d_add(dentry, inode);
346 spin_lock_irqsave(&allpstore_lock, flags);
347 list_add(&private->list, &allpstore);
348 spin_unlock_irqrestore(&allpstore_lock, flags);
353 free_pstore_private(private);
362 * Read all the records from the persistent store. Create
363 * files in our filesystem. Don't warn about -EEXIST errors
364 * when we are re-scanning the backing store looking to add new
367 void pstore_get_records(int quiet)
369 struct pstore_info *psi = psinfo;
372 if (!psi || !pstore_sb)
375 root = pstore_sb->s_root;
377 inode_lock(d_inode(root));
378 pstore_get_backend_records(psi, root, quiet);
379 inode_unlock(d_inode(root));
382 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
388 sb->s_maxbytes = MAX_LFS_FILESIZE;
389 sb->s_blocksize = PAGE_SIZE;
390 sb->s_blocksize_bits = PAGE_SHIFT;
391 sb->s_magic = PSTOREFS_MAGIC;
392 sb->s_op = &pstore_ops;
397 inode = pstore_get_inode(sb);
399 inode->i_mode = S_IFDIR | 0750;
400 inode->i_op = &pstore_dir_inode_operations;
401 inode->i_fop = &simple_dir_operations;
404 sb->s_root = d_make_root(inode);
408 pstore_get_records(0);
413 static struct dentry *pstore_mount(struct file_system_type *fs_type,
414 int flags, const char *dev_name, void *data)
416 return mount_single(fs_type, flags, data, pstore_fill_super);
419 static void pstore_kill_sb(struct super_block *sb)
421 kill_litter_super(sb);
425 static struct file_system_type pstore_fs_type = {
426 .owner = THIS_MODULE,
428 .mount = pstore_mount,
429 .kill_sb = pstore_kill_sb,
432 int __init pstore_init_fs(void)
436 /* Create a convenient mount point for people to access pstore */
437 err = sysfs_create_mount_point(fs_kobj, "pstore");
441 err = register_filesystem(&pstore_fs_type);
443 sysfs_remove_mount_point(fs_kobj, "pstore");
449 void __exit pstore_exit_fs(void)
451 unregister_filesystem(&pstore_fs_type);
452 sysfs_remove_mount_point(fs_kobj, "pstore");