xref: /openbmc/linux/fs/pstore/inode.c (revision 4fc4dca8) 
1 /*
2  * Persistent Storage - ramfs parts.
3  *
4  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License version 2 as
8  *  published by the Free Software Foundation.
9  *
10  *  This program is distributed in the hope that it will be useful,
11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  *  GNU General Public License for more details.
14  *
15  *  You should have received a copy of the GNU General Public License
16  *  along with this program; if not, write to the Free Software
17  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18  */
19 
20 #include <linux/module.h>
21 #include <linux/fs.h>
22 #include <linux/fsnotify.h>
23 #include <linux/pagemap.h>
24 #include <linux/highmem.h>
25 #include <linux/time.h>
26 #include <linux/init.h>
27 #include <linux/list.h>
28 #include <linux/string.h>
29 #include <linux/mount.h>
30 #include <linux/seq_file.h>
31 #include <linux/ramfs.h>
32 #include <linux/parser.h>
33 #include <linux/sched.h>
34 #include <linux/magic.h>
35 #include <linux/pstore.h>
36 #include <linux/slab.h>
37 #include <linux/spinlock.h>
38 #include <linux/uaccess.h>
39 
40 #include "internal.h"
41 
42 #define	PSTORE_NAMELEN	64
43 
44 static DEFINE_SPINLOCK(allpstore_lock);
45 static LIST_HEAD(allpstore);
46 
47 struct pstore_private {
48 	struct list_head list;
49 	struct pstore_record *record;
50 	size_t total_size;
51 };
52 
53 struct pstore_ftrace_seq_data {
54 	const void *ptr;
55 	size_t off;
56 	size_t size;
57 };
58 
59 #define REC_SIZE sizeof(struct pstore_ftrace_record)
60 
61 static void free_pstore_private(struct pstore_private *private)
62 {
63 	if (!private)
64 		return;
65 	if (private->record) {
66 		kfree(private->record->buf);
67 		kfree(private->record);
68 	}
69 	kfree(private);
70 }
71 
72 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
73 {
74 	struct pstore_private *ps = s->private;
75 	struct pstore_ftrace_seq_data *data;
76 
77 	data = kzalloc(sizeof(*data), GFP_KERNEL);
78 	if (!data)
79 		return NULL;
80 
81 	data->off = ps->total_size % REC_SIZE;
82 	data->off += *pos * REC_SIZE;
83 	if (data->off + REC_SIZE > ps->total_size) {
84 		kfree(data);
85 		return NULL;
86 	}
87 
88 	return data;
89 
90 }
91 
92 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
93 {
94 	kfree(v);
95 }
96 
97 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
98 {
99 	struct pstore_private *ps = s->private;
100 	struct pstore_ftrace_seq_data *data = v;
101 
102 	data->off += REC_SIZE;
103 	if (data->off + REC_SIZE > ps->total_size)
104 		return NULL;
105 
106 	(*pos)++;
107 	return data;
108 }
109 
110 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
111 {
112 	struct pstore_private *ps = s->private;
113 	struct pstore_ftrace_seq_data *data = v;
114 	struct pstore_ftrace_record *rec;
115 
116 	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
117 
118 	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
119 		   pstore_ftrace_decode_cpu(rec),
120 		   pstore_ftrace_read_timestamp(rec),
121 		   rec->ip, rec->parent_ip, (void *)rec->ip,
122 		   (void *)rec->parent_ip);
123 
124 	return 0;
125 }
126 
127 static const struct seq_operations pstore_ftrace_seq_ops = {
128 	.start	= pstore_ftrace_seq_start,
129 	.next	= pstore_ftrace_seq_next,
130 	.stop	= pstore_ftrace_seq_stop,
131 	.show	= pstore_ftrace_seq_show,
132 };
133 
134 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
135 						size_t count, loff_t *ppos)
136 {
137 	struct seq_file *sf = file->private_data;
138 	struct pstore_private *ps = sf->private;
139 
140 	if (ps->record->type == PSTORE_TYPE_FTRACE)
141 		return seq_read(file, userbuf, count, ppos);
142 	return simple_read_from_buffer(userbuf, count, ppos,
143 				       ps->record->buf, ps->total_size);
144 }
145 
146 static int pstore_file_open(struct inode *inode, struct file *file)
147 {
148 	struct pstore_private *ps = inode->i_private;
149 	struct seq_file *sf;
150 	int err;
151 	const struct seq_operations *sops = NULL;
152 
153 	if (ps->record->type == PSTORE_TYPE_FTRACE)
154 		sops = &pstore_ftrace_seq_ops;
155 
156 	err = seq_open(file, sops);
157 	if (err < 0)
158 		return err;
159 
160 	sf = file->private_data;
161 	sf->private = ps;
162 
163 	return 0;
164 }
165 
166 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
167 {
168 	struct seq_file *sf = file->private_data;
169 
170 	if (sf->op)
171 		return seq_lseek(file, off, whence);
172 	return default_llseek(file, off, whence);
173 }
174 
175 static const struct file_operations pstore_file_operations = {
176 	.open		= pstore_file_open,
177 	.read		= pstore_file_read,
178 	.llseek		= pstore_file_llseek,
179 	.release	= seq_release,
180 };
181 
182 /*
183  * When a file is unlinked from our file system we call the
184  * platform driver to erase the record from persistent store.
185  */
186 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
187 {
188 	struct pstore_private *p = d_inode(dentry)->i_private;
189 	struct pstore_record *record = p->record;
190 
191 	if (!record->psi->erase)
192 		return -EPERM;
193 
194 	mutex_lock(&record->psi->read_mutex);
195 	record->psi->erase(record);
196 	mutex_unlock(&record->psi->read_mutex);
197 
198 	return simple_unlink(dir, dentry);
199 }
200 
201 static void pstore_evict_inode(struct inode *inode)
202 {
203 	struct pstore_private	*p = inode->i_private;
204 	unsigned long		flags;
205 
206 	clear_inode(inode);
207 	if (p) {
208 		spin_lock_irqsave(&allpstore_lock, flags);
209 		list_del(&p->list);
210 		spin_unlock_irqrestore(&allpstore_lock, flags);
211 		free_pstore_private(p);
212 	}
213 }
214 
215 static const struct inode_operations pstore_dir_inode_operations = {
216 	.lookup		= simple_lookup,
217 	.unlink		= pstore_unlink,
218 };
219 
220 static struct inode *pstore_get_inode(struct super_block *sb)
221 {
222 	struct inode *inode = new_inode(sb);
223 	if (inode) {
224 		inode->i_ino = get_next_ino();
225 		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
226 	}
227 	return inode;
228 }
229 
230 enum {
231 	Opt_kmsg_bytes, Opt_err
232 };
233 
234 static const match_table_t tokens = {
235 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
236 	{Opt_err, NULL}
237 };
238 
239 static void parse_options(char *options)
240 {
241 	char		*p;
242 	substring_t	args[MAX_OPT_ARGS];
243 	int		option;
244 
245 	if (!options)
246 		return;
247 
248 	while ((p = strsep(&options, ",")) != NULL) {
249 		int token;
250 
251 		if (!*p)
252 			continue;
253 
254 		token = match_token(p, tokens, args);
255 		switch (token) {
256 		case Opt_kmsg_bytes:
257 			if (!match_int(&args[0], &option))
258 				pstore_set_kmsg_bytes(option);
259 			break;
260 		}
261 	}
262 }
263 
264 /*
265  * Display the mount options in /proc/mounts.
266  */
267 static int pstore_show_options(struct seq_file *m, struct dentry *root)
268 {
269 	if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
270 		seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
271 	return 0;
272 }
273 
274 static int pstore_remount(struct super_block *sb, int *flags, char *data)
275 {
276 	sync_filesystem(sb);
277 	parse_options(data);
278 
279 	return 0;
280 }
281 
282 static const struct super_operations pstore_ops = {
283 	.statfs		= simple_statfs,
284 	.drop_inode	= generic_delete_inode,
285 	.evict_inode	= pstore_evict_inode,
286 	.remount_fs	= pstore_remount,
287 	.show_options	= pstore_show_options,
288 };
289 
290 static struct super_block *pstore_sb;
291 
292 bool pstore_is_mounted(void)
293 {
294 	return pstore_sb != NULL;
295 }
296 
297 /*
298  * Make a regular file in the root directory of our file system.
299  * Load it up with "size" bytes of data from "buf".
300  * Set the mtime & ctime to the date that this record was originally stored.
301  */
302 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
303 {
304 	struct dentry		*dentry;
305 	struct inode		*inode;
306 	int			rc = 0;
307 	char			name[PSTORE_NAMELEN];
308 	struct pstore_private	*private, *pos;
309 	unsigned long		flags;
310 	size_t			size = record->size + record->ecc_notice_size;
311 
312 	WARN_ON(!inode_is_locked(d_inode(root)));
313 
314 	spin_lock_irqsave(&allpstore_lock, flags);
315 	list_for_each_entry(pos, &allpstore, list) {
316 		if (pos->record->type == record->type &&
317 		    pos->record->id == record->id &&
318 		    pos->record->psi == record->psi) {
319 			rc = -EEXIST;
320 			break;
321 		}
322 	}
323 	spin_unlock_irqrestore(&allpstore_lock, flags);
324 	if (rc)
325 		return rc;
326 
327 	rc = -ENOMEM;
328 	inode = pstore_get_inode(root->d_sb);
329 	if (!inode)
330 		goto fail;
331 	inode->i_mode = S_IFREG | 0444;
332 	inode->i_fop = &pstore_file_operations;
333 	private = kzalloc(sizeof(*private), GFP_KERNEL);
334 	if (!private)
335 		goto fail_alloc;
336 	private->record = record;
337 
338 	scnprintf(name, sizeof(name), "%s-%s-%llu%s",
339 			pstore_type_to_name(record->type),
340 			record->psi->name, record->id,
341 			record->compressed ? ".enc.z" : "");
342 
343 	dentry = d_alloc_name(root, name);
344 	if (!dentry)
345 		goto fail_private;
346 
347 	inode->i_size = private->total_size = size;
348 
349 	inode->i_private = private;
350 
351 	if (record->time.tv_sec)
352 		inode->i_mtime = inode->i_ctime = record->time;
353 
354 	d_add(dentry, inode);
355 
356 	spin_lock_irqsave(&allpstore_lock, flags);
357 	list_add(&private->list, &allpstore);
358 	spin_unlock_irqrestore(&allpstore_lock, flags);
359 
360 	return 0;
361 
362 fail_private:
363 	free_pstore_private(private);
364 fail_alloc:
365 	iput(inode);
366 
367 fail:
368 	return rc;
369 }
370 
371 /*
372  * Read all the records from the persistent store. Create
373  * files in our filesystem.  Don't warn about -EEXIST errors
374  * when we are re-scanning the backing store looking to add new
375  * error records.
376  */
377 void pstore_get_records(int quiet)
378 {
379 	struct pstore_info *psi = psinfo;
380 	struct dentry *root;
381 
382 	if (!psi || !pstore_sb)
383 		return;
384 
385 	root = pstore_sb->s_root;
386 
387 	inode_lock(d_inode(root));
388 	pstore_get_backend_records(psi, root, quiet);
389 	inode_unlock(d_inode(root));
390 }
391 
392 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
393 {
394 	struct inode *inode;
395 
396 	pstore_sb = sb;
397 
398 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
399 	sb->s_blocksize		= PAGE_SIZE;
400 	sb->s_blocksize_bits	= PAGE_SHIFT;
401 	sb->s_magic		= PSTOREFS_MAGIC;
402 	sb->s_op		= &pstore_ops;
403 	sb->s_time_gran		= 1;
404 
405 	parse_options(data);
406 
407 	inode = pstore_get_inode(sb);
408 	if (inode) {
409 		inode->i_mode = S_IFDIR | 0750;
410 		inode->i_op = &pstore_dir_inode_operations;
411 		inode->i_fop = &simple_dir_operations;
412 		inc_nlink(inode);
413 	}
414 	sb->s_root = d_make_root(inode);
415 	if (!sb->s_root)
416 		return -ENOMEM;
417 
418 	pstore_get_records(0);
419 
420 	return 0;
421 }
422 
423 static struct dentry *pstore_mount(struct file_system_type *fs_type,
424 	int flags, const char *dev_name, void *data)
425 {
426 	return mount_single(fs_type, flags, data, pstore_fill_super);
427 }
428 
429 static void pstore_kill_sb(struct super_block *sb)
430 {
431 	kill_litter_super(sb);
432 	pstore_sb = NULL;
433 }
434 
435 static struct file_system_type pstore_fs_type = {
436 	.owner          = THIS_MODULE,
437 	.name		= "pstore",
438 	.mount		= pstore_mount,
439 	.kill_sb	= pstore_kill_sb,
440 };
441 
442 int __init pstore_init_fs(void)
443 {
444 	int err;
445 
446 	/* Create a convenient mount point for people to access pstore */
447 	err = sysfs_create_mount_point(fs_kobj, "pstore");
448 	if (err)
449 		goto out;
450 
451 	err = register_filesystem(&pstore_fs_type);
452 	if (err < 0)
453 		sysfs_remove_mount_point(fs_kobj, "pstore");
454 
455 out:
456 	return err;
457 }
458 
459 void __exit pstore_exit_fs(void)
460 {
461 	unregister_filesystem(&pstore_fs_type);
462 	sysfs_remove_mount_point(fs_kobj, "pstore");
463 }
464