inode.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Persistent Storage - ramfs parts.
  4 *
  5 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/fs.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/seq_file.h>
 18#include <linux/ramfs.h>
 19#include <linux/fs_parser.h>
 20#include <linux/fs_context.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>
 26#include <linux/cleanup.h>
 27
 28#include "internal.h"
 29
 30#define	PSTORE_NAMELEN	64
 31
 32static DEFINE_MUTEX(records_list_lock);
 33static LIST_HEAD(records_list);
 34
 35static DEFINE_MUTEX(pstore_sb_lock);
 36static struct super_block *pstore_sb;
 37
 38DEFINE_FREE(pstore_iput, struct inode *, if (_T) iput(_T))
 39
 40struct pstore_private {
 41	struct list_head list;
 42	struct dentry *dentry;
 43	struct pstore_record *record;
 44	size_t total_size;
 45};
 46
 47struct pstore_ftrace_seq_data {
 48	const void *ptr;
 49	size_t off;
 50	size_t size;
 51};
 52
 53#define REC_SIZE sizeof(struct pstore_ftrace_record)
 54
 55static void free_pstore_private(struct pstore_private *private)
 56{
 57	if (!private)
 58		return;
 59	if (private->record) {
 60		kvfree(private->record->buf);
 61		kfree(private->record->priv);
 62		kfree(private->record);
 63	}
 64	kfree(private);
 65}
 66DEFINE_FREE(pstore_private, struct pstore_private *, free_pstore_private(_T));
 67
 68static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
 69{
 70	struct pstore_private *ps = s->private;
 71	struct pstore_ftrace_seq_data *data __free(kfree) = NULL;
 72
 73	data = kzalloc(sizeof(*data), GFP_KERNEL);
 74	if (!data)
 75		return NULL;
 76
 77	data->off = ps->total_size % REC_SIZE;
 78	data->off += *pos * REC_SIZE;
 79	if (data->off + REC_SIZE > ps->total_size)
 80		return NULL;
 81
 82	return_ptr(data);
 83}
 84
 85static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
 86{
 87	kfree(v);
 88}
 89
 90static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
 91{
 92	struct pstore_private *ps = s->private;
 93	struct pstore_ftrace_seq_data *data = v;
 94
 95	(*pos)++;
 96	data->off += REC_SIZE;
 97	if (data->off + REC_SIZE > ps->total_size)
 98		return NULL;
 99
100	return data;
101}
102
103static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
104{
105	struct pstore_private *ps = s->private;
106	struct pstore_ftrace_seq_data *data = v;
107	struct pstore_ftrace_record *rec;
108
109	if (!data)
110		return 0;
111
112	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
113
114	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
115		   pstore_ftrace_decode_cpu(rec),
116		   pstore_ftrace_read_timestamp(rec),
117		   rec->ip, rec->parent_ip, (void *)rec->ip,
118		   (void *)rec->parent_ip);
119
120	return 0;
121}
122
123static const struct seq_operations pstore_ftrace_seq_ops = {
124	.start	= pstore_ftrace_seq_start,
125	.next	= pstore_ftrace_seq_next,
126	.stop	= pstore_ftrace_seq_stop,
127	.show	= pstore_ftrace_seq_show,
128};
129
130static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
131						size_t count, loff_t *ppos)
132{
133	struct seq_file *sf = file->private_data;
134	struct pstore_private *ps = sf->private;
135
136	if (ps->record->type == PSTORE_TYPE_FTRACE)
137		return seq_read(file, userbuf, count, ppos);
138	return simple_read_from_buffer(userbuf, count, ppos,
139				       ps->record->buf, ps->total_size);
140}
141
142static int pstore_file_open(struct inode *inode, struct file *file)
143{
144	struct pstore_private *ps = inode->i_private;
145	struct seq_file *sf;
146	int err;
147	const struct seq_operations *sops = NULL;
148
149	if (ps->record->type == PSTORE_TYPE_FTRACE)
150		sops = &pstore_ftrace_seq_ops;
151
152	err = seq_open(file, sops);
153	if (err < 0)
154		return err;
155
156	sf = file->private_data;
157	sf->private = ps;
158
159	return 0;
160}
161
162static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
163{
164	struct seq_file *sf = file->private_data;
165
166	if (sf->op)
167		return seq_lseek(file, off, whence);
168	return default_llseek(file, off, whence);
169}
170
171static const struct file_operations pstore_file_operations = {
172	.open		= pstore_file_open,
173	.read		= pstore_file_read,
174	.llseek		= pstore_file_llseek,
175	.release	= seq_release,
176};
177
178/*
179 * When a file is unlinked from our file system we call the
180 * platform driver to erase the record from persistent store.
181 */
182static int pstore_unlink(struct inode *dir, struct dentry *dentry)
183{
184	struct pstore_private *p = d_inode(dentry)->i_private;
185	struct pstore_record *record = p->record;
186
187	if (!record->psi->erase)
188		return -EPERM;
189
190	/* Make sure we can't race while removing this file. */
191	scoped_guard(mutex, &records_list_lock) {
192		if (!list_empty(&p->list))
193			list_del_init(&p->list);
194		else
195			return -ENOENT;
196		p->dentry = NULL;
197	}
198
199	scoped_guard(mutex, &record->psi->read_mutex)
200		record->psi->erase(record);
201
202	return simple_unlink(dir, dentry);
203}
204
205static void pstore_evict_inode(struct inode *inode)
206{
207	struct pstore_private	*p = inode->i_private;
208
209	clear_inode(inode);
210	free_pstore_private(p);
211}
212
213static const struct inode_operations pstore_dir_inode_operations = {
214	.lookup		= simple_lookup,
215	.unlink		= pstore_unlink,
216};
217
218static struct inode *pstore_get_inode(struct super_block *sb)
219{
220	struct inode *inode = new_inode(sb);
221	if (inode) {
222		inode->i_ino = get_next_ino();
223		simple_inode_init_ts(inode);
224	}
225	return inode;
226}
227
228enum {
229	Opt_kmsg_bytes
230};
231
232static const struct fs_parameter_spec pstore_param_spec[] = {
233	fsparam_u32	("kmsg_bytes",	Opt_kmsg_bytes),
234	{}
235};
236
237struct pstore_context {
238	unsigned int kmsg_bytes;
239};
240
241static int pstore_parse_param(struct fs_context *fc, struct fs_parameter *param)
242{
243	struct pstore_context *ctx = fc->fs_private;
244	struct fs_parse_result result;
245	int opt;
246
247	opt = fs_parse(fc, pstore_param_spec, param, &result);
248	/* pstore has historically ignored invalid kmsg_bytes param */
249	if (opt < 0)
250		return 0;
251
252	switch (opt) {
253	case Opt_kmsg_bytes:
254		ctx->kmsg_bytes = result.uint_32;
255		break;
256	default:
257		return -EINVAL;
258	}
259
260	return 0;
261}
262
263/*
264 * Display the mount options in /proc/mounts.
265 */
266static int pstore_show_options(struct seq_file *m, struct dentry *root)
267{
268	if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
269		seq_printf(m, ",kmsg_bytes=%u", kmsg_bytes);
270	return 0;
271}
272
273static int pstore_reconfigure(struct fs_context *fc)
274{
275	struct pstore_context *ctx = fc->fs_private;
276
277	sync_filesystem(fc->root->d_sb);
278	pstore_set_kmsg_bytes(ctx->kmsg_bytes);
279
280	return 0;
281}
282
283static const struct super_operations pstore_ops = {
284	.statfs		= simple_statfs,
285	.drop_inode	= inode_just_drop,
286	.evict_inode	= pstore_evict_inode,
287	.show_options	= pstore_show_options,
288};
289
290static struct dentry *psinfo_lock_root(void)
291{
292	struct dentry *root;
293
294	guard(mutex)(&pstore_sb_lock);
295	/*
296	 * Having no backend is fine -- no records appear.
297	 * Not being mounted is fine -- nothing to do.
298	 */
299	if (!psinfo || !pstore_sb)
300		return NULL;
301
302	root = pstore_sb->s_root;
303	inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
304
305	return root;
306}
307
308int pstore_put_backend_records(struct pstore_info *psi)
309{
310	struct pstore_private *pos, *tmp;
311	struct dentry *root;
312
313	root = psinfo_lock_root();
314	if (!root)
315		return 0;
316
317	scoped_guard(mutex, &records_list_lock) {
318		list_for_each_entry_safe(pos, tmp, &records_list, list) {
319			if (pos->record->psi == psi) {
320				list_del_init(&pos->list);
321				locked_recursive_removal(pos->dentry, NULL);
322				pos->dentry = NULL;
323			}
324		}
325	}
326
327	inode_unlock(d_inode(root));
328
329	return 0;
330}
331
332/*
333 * Make a regular file in the root directory of our file system.
334 * Load it up with "size" bytes of data from "buf".
335 * Set the mtime & ctime to the date that this record was originally stored.
336 */
337int pstore_mkfile(struct dentry *root, struct pstore_record *record)
338{
339	struct dentry		*dentry;
340	struct inode		*inode __free(pstore_iput) = NULL;
341	char			name[PSTORE_NAMELEN];
342	struct pstore_private	*private __free(pstore_private) = NULL, *pos;
343	size_t			size = record->size + record->ecc_notice_size;
344
345	if (WARN_ON(!inode_is_locked(d_inode(root))))
346		return -EINVAL;
347
348	guard(mutex)(&records_list_lock);
349
350	/* Skip records that are already present in the filesystem. */
351	list_for_each_entry(pos, &records_list, list) {
352		if (pos->record->type == record->type &&
353		    pos->record->id == record->id &&
354		    pos->record->psi == record->psi)
355			return -EEXIST;
356	}
357
358	inode = pstore_get_inode(root->d_sb);
359	if (!inode)
360		return -ENOMEM;
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" : "");
367
368	private = kzalloc(sizeof(*private), GFP_KERNEL);
369	if (!private)
370		return -ENOMEM;
371
372	dentry = d_alloc_name(root, name);
373	if (!dentry)
374		return -ENOMEM;
375
376	private->dentry = dentry; // borrowed
377	private->record = record;
378	inode->i_size = private->total_size = size;
379	inode->i_private = private;
380
381	if (record->time.tv_sec)
382		inode_set_mtime_to_ts(inode,
383				      inode_set_ctime_to_ts(inode, record->time));
384
385	d_make_persistent(dentry, no_free_ptr(inode));
386	dput(dentry);
387
388	list_add(&(no_free_ptr(private))->list, &records_list);
389
390	return 0;
391}
392
393/*
394 * Read all the records from the persistent store. Create
395 * files in our filesystem.  Don't warn about -EEXIST errors
396 * when we are re-scanning the backing store looking to add new
397 * error records.
398 */
399void pstore_get_records(int quiet)
400{
401	struct dentry *root;
402
403	root = psinfo_lock_root();
404	if (!root)
405		return;
406
407	pstore_get_backend_records(psinfo, root, quiet);
408	inode_unlock(d_inode(root));
409}
410
411static int pstore_fill_super(struct super_block *sb, struct fs_context *fc)
412{
413	struct pstore_context *ctx = fc->fs_private;
414	struct inode *inode;
415
416	sb->s_maxbytes		= MAX_LFS_FILESIZE;
417	sb->s_blocksize		= PAGE_SIZE;
418	sb->s_blocksize_bits	= PAGE_SHIFT;
419	sb->s_magic		= PSTOREFS_MAGIC;
420	sb->s_op		= &pstore_ops;
421	sb->s_time_gran		= 1;
422
423	pstore_set_kmsg_bytes(ctx->kmsg_bytes);
424
425	inode = pstore_get_inode(sb);
426	if (inode) {
427		inode->i_mode = S_IFDIR | 0750;
428		inode->i_op = &pstore_dir_inode_operations;
429		inode->i_fop = &simple_dir_operations;
430		inc_nlink(inode);
431	}
432	sb->s_root = d_make_root(inode);
433	if (!sb->s_root)
434		return -ENOMEM;
435
436	scoped_guard(mutex, &pstore_sb_lock)
437		pstore_sb = sb;
438
439	pstore_get_records(0);
440
441	return 0;
442}
443
444static int pstore_get_tree(struct fs_context *fc)
445{
446	if (fc->root)
447		return pstore_reconfigure(fc);
448
449	return get_tree_single(fc, pstore_fill_super);
450}
451
452static void pstore_free_fc(struct fs_context *fc)
453{
454	kfree(fc->fs_private);
455}
456
457static const struct fs_context_operations pstore_context_ops = {
458	.parse_param	= pstore_parse_param,
459	.get_tree	= pstore_get_tree,
460	.reconfigure	= pstore_reconfigure,
461	.free		= pstore_free_fc,
462};
463
464static void pstore_kill_sb(struct super_block *sb)
465{
466	guard(mutex)(&pstore_sb_lock);
467	WARN_ON(pstore_sb && pstore_sb != sb);
468
469	kill_anon_super(sb);
470	pstore_sb = NULL;
471
472	guard(mutex)(&records_list_lock);
473	INIT_LIST_HEAD(&records_list);
474}
475
476static int pstore_init_fs_context(struct fs_context *fc)
477{
478	struct pstore_context *ctx;
479
480	ctx = kzalloc(sizeof(struct pstore_context), GFP_KERNEL);
481	if (!ctx)
482		return -ENOMEM;
483
484	/*
485	 * Global kmsg_bytes is initialized to default, and updated
486	 * every time we (re)mount the single-sb filesystem with the
487	 * option specified.
488	 */
489	ctx->kmsg_bytes = kmsg_bytes;
490
491	fc->fs_private = ctx;
492	fc->ops = &pstore_context_ops;
493
494	return 0;
495}
496
497static struct file_system_type pstore_fs_type = {
498	.owner          = THIS_MODULE,
499	.name		= "pstore",
500	.kill_sb	= pstore_kill_sb,
501	.init_fs_context = pstore_init_fs_context,
502	.parameters	= pstore_param_spec,
503};
504
505int __init pstore_init_fs(void)
506{
507	int err;
508
509	/* Create a convenient mount point for people to access pstore */
510	err = sysfs_create_mount_point(fs_kobj, "pstore");
511	if (err)
512		goto out;
513
514	err = register_filesystem(&pstore_fs_type);
515	if (err < 0)
516		sysfs_remove_mount_point(fs_kobj, "pstore");
517
518out:
519	return err;
520}
521
522void __exit pstore_exit_fs(void)
523{
524	unregister_filesystem(&pstore_fs_type);
525	sysfs_remove_mount_point(fs_kobj, "pstore");
526}