xref: /openbmc/linux/fs/pstore/inode.c (revision 861e10be) 
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_info *psi;
50 	enum pstore_type_id type;
51 	u64	id;
52 	int	count;
53 	ssize_t	size;
54 	char	data[];
55 };
56 
57 struct pstore_ftrace_seq_data {
58 	const void *ptr;
59 	size_t off;
60 	size_t size;
61 };
62 
63 #define REC_SIZE sizeof(struct pstore_ftrace_record)
64 
65 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
66 {
67 	struct pstore_private *ps = s->private;
68 	struct pstore_ftrace_seq_data *data;
69 
70 	data = kzalloc(sizeof(*data), GFP_KERNEL);
71 	if (!data)
72 		return NULL;
73 
74 	data->off = ps->size % REC_SIZE;
75 	data->off += *pos * REC_SIZE;
76 	if (data->off + REC_SIZE > ps->size) {
77 		kfree(data);
78 		return NULL;
79 	}
80 
81 	return data;
82 
83 }
84 
85 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
86 {
87 	kfree(v);
88 }
89 
90 static 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 	data->off += REC_SIZE;
96 	if (data->off + REC_SIZE > ps->size)
97 		return NULL;
98 
99 	(*pos)++;
100 	return data;
101 }
102 
103 static 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 = (void *)(ps->data + data->off);
108 
109 	seq_printf(s, "%d %08lx  %08lx  %pf <- %pF\n",
110 		pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
111 		(void *)rec->ip, (void *)rec->parent_ip);
112 
113 	return 0;
114 }
115 
116 static const struct seq_operations pstore_ftrace_seq_ops = {
117 	.start	= pstore_ftrace_seq_start,
118 	.next	= pstore_ftrace_seq_next,
119 	.stop	= pstore_ftrace_seq_stop,
120 	.show	= pstore_ftrace_seq_show,
121 };
122 
123 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
124 						size_t count, loff_t *ppos)
125 {
126 	struct seq_file *sf = file->private_data;
127 	struct pstore_private *ps = sf->private;
128 
129 	if (ps->type == PSTORE_TYPE_FTRACE)
130 		return seq_read(file, userbuf, count, ppos);
131 	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
132 }
133 
134 static int pstore_file_open(struct inode *inode, struct file *file)
135 {
136 	struct pstore_private *ps = inode->i_private;
137 	struct seq_file *sf;
138 	int err;
139 	const struct seq_operations *sops = NULL;
140 
141 	if (ps->type == PSTORE_TYPE_FTRACE)
142 		sops = &pstore_ftrace_seq_ops;
143 
144 	err = seq_open(file, sops);
145 	if (err < 0)
146 		return err;
147 
148 	sf = file->private_data;
149 	sf->private = ps;
150 
151 	return 0;
152 }
153 
154 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
155 {
156 	struct seq_file *sf = file->private_data;
157 
158 	if (sf->op)
159 		return seq_lseek(file, off, whence);
160 	return default_llseek(file, off, whence);
161 }
162 
163 static const struct file_operations pstore_file_operations = {
164 	.open		= pstore_file_open,
165 	.read		= pstore_file_read,
166 	.llseek		= pstore_file_llseek,
167 	.release	= seq_release,
168 };
169 
170 /*
171  * When a file is unlinked from our file system we call the
172  * platform driver to erase the record from persistent store.
173  */
174 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
175 {
176 	struct pstore_private *p = dentry->d_inode->i_private;
177 
178 	if (p->psi->erase)
179 		p->psi->erase(p->type, p->id, p->count,
180 			      dentry->d_inode->i_ctime, p->psi);
181 
182 	return simple_unlink(dir, dentry);
183 }
184 
185 static void pstore_evict_inode(struct inode *inode)
186 {
187 	struct pstore_private	*p = inode->i_private;
188 	unsigned long		flags;
189 
190 	clear_inode(inode);
191 	if (p) {
192 		spin_lock_irqsave(&allpstore_lock, flags);
193 		list_del(&p->list);
194 		spin_unlock_irqrestore(&allpstore_lock, flags);
195 		kfree(p);
196 	}
197 }
198 
199 static const struct inode_operations pstore_dir_inode_operations = {
200 	.lookup		= simple_lookup,
201 	.unlink		= pstore_unlink,
202 };
203 
204 static struct inode *pstore_get_inode(struct super_block *sb)
205 {
206 	struct inode *inode = new_inode(sb);
207 	if (inode) {
208 		inode->i_ino = get_next_ino();
209 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
210 	}
211 	return inode;
212 }
213 
214 enum {
215 	Opt_kmsg_bytes, Opt_err
216 };
217 
218 static const match_table_t tokens = {
219 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
220 	{Opt_err, NULL}
221 };
222 
223 static void parse_options(char *options)
224 {
225 	char		*p;
226 	substring_t	args[MAX_OPT_ARGS];
227 	int		option;
228 
229 	if (!options)
230 		return;
231 
232 	while ((p = strsep(&options, ",")) != NULL) {
233 		int token;
234 
235 		if (!*p)
236 			continue;
237 
238 		token = match_token(p, tokens, args);
239 		switch (token) {
240 		case Opt_kmsg_bytes:
241 			if (!match_int(&args[0], &option))
242 				pstore_set_kmsg_bytes(option);
243 			break;
244 		}
245 	}
246 }
247 
248 static int pstore_remount(struct super_block *sb, int *flags, char *data)
249 {
250 	parse_options(data);
251 
252 	return 0;
253 }
254 
255 static const struct super_operations pstore_ops = {
256 	.statfs		= simple_statfs,
257 	.drop_inode	= generic_delete_inode,
258 	.evict_inode	= pstore_evict_inode,
259 	.remount_fs	= pstore_remount,
260 	.show_options	= generic_show_options,
261 };
262 
263 static struct super_block *pstore_sb;
264 
265 int pstore_is_mounted(void)
266 {
267 	return pstore_sb != NULL;
268 }
269 
270 /*
271  * Make a regular file in the root directory of our file system.
272  * Load it up with "size" bytes of data from "buf".
273  * Set the mtime & ctime to the date that this record was originally stored.
274  */
275 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
276 		  char *data, size_t size, struct timespec time,
277 		  struct pstore_info *psi)
278 {
279 	struct dentry		*root = pstore_sb->s_root;
280 	struct dentry		*dentry;
281 	struct inode		*inode;
282 	int			rc = 0;
283 	char			name[PSTORE_NAMELEN];
284 	struct pstore_private	*private, *pos;
285 	unsigned long		flags;
286 
287 	spin_lock_irqsave(&allpstore_lock, flags);
288 	list_for_each_entry(pos, &allpstore, list) {
289 		if (pos->type == type &&
290 		    pos->id == id &&
291 		    pos->psi == psi) {
292 			rc = -EEXIST;
293 			break;
294 		}
295 	}
296 	spin_unlock_irqrestore(&allpstore_lock, flags);
297 	if (rc)
298 		return rc;
299 
300 	rc = -ENOMEM;
301 	inode = pstore_get_inode(pstore_sb);
302 	if (!inode)
303 		goto fail;
304 	inode->i_mode = S_IFREG | 0444;
305 	inode->i_fop = &pstore_file_operations;
306 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
307 	if (!private)
308 		goto fail_alloc;
309 	private->type = type;
310 	private->id = id;
311 	private->count = count;
312 	private->psi = psi;
313 
314 	switch (type) {
315 	case PSTORE_TYPE_DMESG:
316 		sprintf(name, "dmesg-%s-%lld", psname, id);
317 		break;
318 	case PSTORE_TYPE_CONSOLE:
319 		sprintf(name, "console-%s", psname);
320 		break;
321 	case PSTORE_TYPE_FTRACE:
322 		sprintf(name, "ftrace-%s", psname);
323 		break;
324 	case PSTORE_TYPE_MCE:
325 		sprintf(name, "mce-%s-%lld", psname, id);
326 		break;
327 	case PSTORE_TYPE_UNKNOWN:
328 		sprintf(name, "unknown-%s-%lld", psname, id);
329 		break;
330 	default:
331 		sprintf(name, "type%d-%s-%lld", type, psname, id);
332 		break;
333 	}
334 
335 	mutex_lock(&root->d_inode->i_mutex);
336 
337 	rc = -ENOSPC;
338 	dentry = d_alloc_name(root, name);
339 	if (IS_ERR(dentry))
340 		goto fail_lockedalloc;
341 
342 	memcpy(private->data, data, size);
343 	inode->i_size = private->size = size;
344 
345 	inode->i_private = private;
346 
347 	if (time.tv_sec)
348 		inode->i_mtime = inode->i_ctime = time;
349 
350 	d_add(dentry, inode);
351 
352 	spin_lock_irqsave(&allpstore_lock, flags);
353 	list_add(&private->list, &allpstore);
354 	spin_unlock_irqrestore(&allpstore_lock, flags);
355 
356 	mutex_unlock(&root->d_inode->i_mutex);
357 
358 	return 0;
359 
360 fail_lockedalloc:
361 	mutex_unlock(&root->d_inode->i_mutex);
362 	kfree(private);
363 fail_alloc:
364 	iput(inode);
365 
366 fail:
367 	return rc;
368 }
369 
370 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
371 {
372 	struct inode *inode;
373 
374 	save_mount_options(sb, data);
375 
376 	pstore_sb = sb;
377 
378 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
379 	sb->s_blocksize		= PAGE_CACHE_SIZE;
380 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
381 	sb->s_magic		= PSTOREFS_MAGIC;
382 	sb->s_op		= &pstore_ops;
383 	sb->s_time_gran		= 1;
384 
385 	parse_options(data);
386 
387 	inode = pstore_get_inode(sb);
388 	if (inode) {
389 		inode->i_mode = S_IFDIR | 0755;
390 		inode->i_op = &pstore_dir_inode_operations;
391 		inode->i_fop = &simple_dir_operations;
392 		inc_nlink(inode);
393 	}
394 	sb->s_root = d_make_root(inode);
395 	if (!sb->s_root)
396 		return -ENOMEM;
397 
398 	pstore_get_records(0);
399 
400 	return 0;
401 }
402 
403 static struct dentry *pstore_mount(struct file_system_type *fs_type,
404 	int flags, const char *dev_name, void *data)
405 {
406 	return mount_single(fs_type, flags, data, pstore_fill_super);
407 }
408 
409 static void pstore_kill_sb(struct super_block *sb)
410 {
411 	kill_litter_super(sb);
412 	pstore_sb = NULL;
413 }
414 
415 static struct file_system_type pstore_fs_type = {
416 	.name		= "pstore",
417 	.mount		= pstore_mount,
418 	.kill_sb	= pstore_kill_sb,
419 };
420 
421 static int __init init_pstore_fs(void)
422 {
423 	return register_filesystem(&pstore_fs_type);
424 }
425 module_init(init_pstore_fs)
426 
427 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
428 MODULE_LICENSE("GPL");
429