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/uaccess.h>
29 #define PSTORE_NAMELEN 64
31 static DEFINE_MUTEX(records_list_lock);
32 static LIST_HEAD(records_list);
34 static DEFINE_MUTEX(pstore_sb_lock);
35 static struct super_block *pstore_sb;
37 struct pstore_private {
38 struct list_head list;
39 struct dentry *dentry;
40 struct pstore_record *record;
44 struct pstore_ftrace_seq_data {
50 #define REC_SIZE sizeof(struct pstore_ftrace_record)
52 static void free_pstore_private(struct pstore_private *private)
56 if (private->record) {
57 kfree(private->record->buf);
58 kfree(private->record->priv);
59 kfree(private->record);
64 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
66 struct pstore_private *ps = s->private;
67 struct pstore_ftrace_seq_data *data;
69 data = kzalloc(sizeof(*data), GFP_KERNEL);
73 data->off = ps->total_size % REC_SIZE;
74 data->off += *pos * REC_SIZE;
75 if (data->off + REC_SIZE > ps->total_size) {
84 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
89 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
91 struct pstore_private *ps = s->private;
92 struct pstore_ftrace_seq_data *data = v;
95 data->off += REC_SIZE;
96 if (data->off + REC_SIZE > ps->total_size)
102 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
104 struct pstore_private *ps = s->private;
105 struct pstore_ftrace_seq_data *data = v;
106 struct pstore_ftrace_record *rec;
111 rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
113 seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %ps <- %pS\n",
114 pstore_ftrace_decode_cpu(rec),
115 pstore_ftrace_read_timestamp(rec),
116 rec->ip, rec->parent_ip, (void *)rec->ip,
117 (void *)rec->parent_ip);
122 static const struct seq_operations pstore_ftrace_seq_ops = {
123 .start = pstore_ftrace_seq_start,
124 .next = pstore_ftrace_seq_next,
125 .stop = pstore_ftrace_seq_stop,
126 .show = pstore_ftrace_seq_show,
129 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
130 size_t count, loff_t *ppos)
132 struct seq_file *sf = file->private_data;
133 struct pstore_private *ps = sf->private;
135 if (ps->record->type == PSTORE_TYPE_FTRACE)
136 return seq_read(file, userbuf, count, ppos);
137 return simple_read_from_buffer(userbuf, count, ppos,
138 ps->record->buf, ps->total_size);
141 static int pstore_file_open(struct inode *inode, struct file *file)
143 struct pstore_private *ps = inode->i_private;
146 const struct seq_operations *sops = NULL;
148 if (ps->record->type == PSTORE_TYPE_FTRACE)
149 sops = &pstore_ftrace_seq_ops;
151 err = seq_open(file, sops);
155 sf = file->private_data;
161 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
163 struct seq_file *sf = file->private_data;
166 return seq_lseek(file, off, whence);
167 return default_llseek(file, off, whence);
170 static const struct file_operations pstore_file_operations = {
171 .open = pstore_file_open,
172 .read = pstore_file_read,
173 .llseek = pstore_file_llseek,
174 .release = seq_release,
178 * When a file is unlinked from our file system we call the
179 * platform driver to erase the record from persistent store.
181 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
183 struct pstore_private *p = d_inode(dentry)->i_private;
184 struct pstore_record *record = p->record;
186 if (!record->psi->erase)
189 /* Make sure we can't race while removing this file. */
190 scoped_guard(mutex, &records_list_lock) {
191 if (!list_empty(&p->list))
192 list_del_init(&p->list);
198 scoped_guard(mutex, &record->psi->read_mutex)
199 record->psi->erase(record);
201 return simple_unlink(dir, dentry);
204 static void pstore_evict_inode(struct inode *inode)
206 struct pstore_private *p = inode->i_private;
209 free_pstore_private(p);
212 static const struct inode_operations pstore_dir_inode_operations = {
213 .lookup = simple_lookup,
214 .unlink = pstore_unlink,
217 static struct inode *pstore_get_inode(struct super_block *sb)
219 struct inode *inode = new_inode(sb);
221 inode->i_ino = get_next_ino();
222 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
228 Opt_kmsg_bytes, Opt_err
231 static const match_table_t tokens = {
232 {Opt_kmsg_bytes, "kmsg_bytes=%u"},
236 static void parse_options(char *options)
239 substring_t args[MAX_OPT_ARGS];
245 while ((p = strsep(&options, ",")) != NULL) {
251 token = match_token(p, tokens, args);
254 if (!match_int(&args[0], &option))
255 pstore_set_kmsg_bytes(option);
262 * Display the mount options in /proc/mounts.
264 static int pstore_show_options(struct seq_file *m, struct dentry *root)
266 if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
267 seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
271 static int pstore_remount(struct super_block *sb, int *flags, char *data)
279 static const struct super_operations pstore_ops = {
280 .statfs = simple_statfs,
281 .drop_inode = generic_delete_inode,
282 .evict_inode = pstore_evict_inode,
283 .remount_fs = pstore_remount,
284 .show_options = pstore_show_options,
287 static struct dentry *psinfo_lock_root(void)
291 guard(mutex)(&pstore_sb_lock);
293 * Having no backend is fine -- no records appear.
294 * Not being mounted is fine -- nothing to do.
296 if (!psinfo || !pstore_sb)
299 root = pstore_sb->s_root;
300 inode_lock(d_inode(root));
305 int pstore_put_backend_records(struct pstore_info *psi)
307 struct pstore_private *pos, *tmp;
310 root = psinfo_lock_root();
314 scoped_guard(mutex, &records_list_lock) {
315 list_for_each_entry_safe(pos, tmp, &records_list, list) {
316 if (pos->record->psi == psi) {
317 list_del_init(&pos->list);
318 d_invalidate(pos->dentry);
319 simple_unlink(d_inode(root), pos->dentry);
325 inode_unlock(d_inode(root));
331 * Make a regular file in the root directory of our file system.
332 * Load it up with "size" bytes of data from "buf".
333 * Set the mtime & ctime to the date that this record was originally stored.
335 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
337 struct dentry *dentry;
340 char name[PSTORE_NAMELEN];
341 struct pstore_private *private, *pos;
342 size_t size = record->size + record->ecc_notice_size;
344 if (WARN_ON(!inode_is_locked(d_inode(root))))
347 guard(mutex)(&records_list_lock);
349 /* Skip records that are already present in the filesystem. */
350 list_for_each_entry(pos, &records_list, list) {
351 if (pos->record->type == record->type &&
352 pos->record->id == record->id &&
353 pos->record->psi == record->psi)
358 inode = pstore_get_inode(root->d_sb);
361 inode->i_mode = S_IFREG | 0444;
362 inode->i_fop = &pstore_file_operations;
363 scnprintf(name, sizeof(name), "%s-%s-%llu%s",
364 pstore_type_to_name(record->type),
365 record->psi->name, record->id,
366 record->compressed ? ".enc.z" : "");
368 private = kzalloc(sizeof(*private), GFP_KERNEL);
372 dentry = d_alloc_name(root, name);
376 private->dentry = dentry;
377 private->record = record;
378 inode->i_size = private->total_size = size;
379 inode->i_private = private;
381 if (record->time.tv_sec)
382 inode->i_mtime = inode->i_ctime = record->time;
384 d_add(dentry, inode);
386 list_add(&private->list, &records_list);
391 free_pstore_private(private);
398 * Read all the records from the persistent store. Create
399 * files in our filesystem. Don't warn about -EEXIST errors
400 * when we are re-scanning the backing store looking to add new
403 void pstore_get_records(int quiet)
407 root = psinfo_lock_root();
411 pstore_get_backend_records(psinfo, root, quiet);
412 inode_unlock(d_inode(root));
415 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
419 sb->s_maxbytes = MAX_LFS_FILESIZE;
420 sb->s_blocksize = PAGE_SIZE;
421 sb->s_blocksize_bits = PAGE_SHIFT;
422 sb->s_magic = PSTOREFS_MAGIC;
423 sb->s_op = &pstore_ops;
428 inode = pstore_get_inode(sb);
430 inode->i_mode = S_IFDIR | 0750;
431 inode->i_op = &pstore_dir_inode_operations;
432 inode->i_fop = &simple_dir_operations;
435 sb->s_root = d_make_root(inode);
439 scoped_guard(mutex, &pstore_sb_lock)
442 pstore_get_records(0);
447 static struct dentry *pstore_mount(struct file_system_type *fs_type,
448 int flags, const char *dev_name, void *data)
450 return mount_single(fs_type, flags, data, pstore_fill_super);
453 static void pstore_kill_sb(struct super_block *sb)
455 guard(mutex)(&pstore_sb_lock);
456 WARN_ON(pstore_sb && pstore_sb != sb);
458 kill_litter_super(sb);
461 guard(mutex)(&records_list_lock);
462 INIT_LIST_HEAD(&records_list);
465 static struct file_system_type pstore_fs_type = {
466 .owner = THIS_MODULE,
468 .mount = pstore_mount,
469 .kill_sb = pstore_kill_sb,
472 int __init pstore_init_fs(void)
476 /* Create a convenient mount point for people to access pstore */
477 err = sysfs_create_mount_point(fs_kobj, "pstore");
481 err = register_filesystem(&pstore_fs_type);
483 sysfs_remove_mount_point(fs_kobj, "pstore");
489 void __exit pstore_exit_fs(void)
491 unregister_filesystem(&pstore_fs_type);
492 sysfs_remove_mount_point(fs_kobj, "pstore");