xref: /openbmc/linux/fs/pstore/inode.c (revision 95e9fd10) 
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 	ssize_t	size;
53 	char	data[];
54 };
55 
56 struct pstore_ftrace_seq_data {
57 	const void *ptr;
58 	size_t off;
59 	size_t size;
60 };
61 
62 #define REC_SIZE sizeof(struct pstore_ftrace_record)
63 
64 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
65 {
66 	struct pstore_private *ps = s->private;
67 	struct pstore_ftrace_seq_data *data;
68 
69 	data = kzalloc(sizeof(*data), GFP_KERNEL);
70 	if (!data)
71 		return NULL;
72 
73 	data->off = ps->size % REC_SIZE;
74 	data->off += *pos * REC_SIZE;
75 	if (data->off + REC_SIZE > ps->size) {
76 		kfree(data);
77 		return NULL;
78 	}
79 
80 	return data;
81 
82 }
83 
84 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
85 {
86 	kfree(v);
87 }
88 
89 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
90 {
91 	struct pstore_private *ps = s->private;
92 	struct pstore_ftrace_seq_data *data = v;
93 
94 	data->off += REC_SIZE;
95 	if (data->off + REC_SIZE > ps->size)
96 		return NULL;
97 
98 	(*pos)++;
99 	return data;
100 }
101 
102 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
103 {
104 	struct pstore_private *ps = s->private;
105 	struct pstore_ftrace_seq_data *data = v;
106 	struct pstore_ftrace_record *rec = (void *)(ps->data + data->off);
107 
108 	seq_printf(s, "%d %08lx  %08lx  %pf <- %pF\n",
109 		pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
110 		(void *)rec->ip, (void *)rec->parent_ip);
111 
112 	return 0;
113 }
114 
115 static const struct seq_operations pstore_ftrace_seq_ops = {
116 	.start	= pstore_ftrace_seq_start,
117 	.next	= pstore_ftrace_seq_next,
118 	.stop	= pstore_ftrace_seq_stop,
119 	.show	= pstore_ftrace_seq_show,
120 };
121 
122 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
123 						size_t count, loff_t *ppos)
124 {
125 	struct seq_file *sf = file->private_data;
126 	struct pstore_private *ps = sf->private;
127 
128 	if (ps->type == PSTORE_TYPE_FTRACE)
129 		return seq_read(file, userbuf, count, ppos);
130 	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
131 }
132 
133 static int pstore_file_open(struct inode *inode, struct file *file)
134 {
135 	struct pstore_private *ps = inode->i_private;
136 	struct seq_file *sf;
137 	int err;
138 	const struct seq_operations *sops = NULL;
139 
140 	if (ps->type == PSTORE_TYPE_FTRACE)
141 		sops = &pstore_ftrace_seq_ops;
142 
143 	err = seq_open(file, sops);
144 	if (err < 0)
145 		return err;
146 
147 	sf = file->private_data;
148 	sf->private = ps;
149 
150 	return 0;
151 }
152 
153 static loff_t pstore_file_llseek(struct file *file, loff_t off, int origin)
154 {
155 	struct seq_file *sf = file->private_data;
156 
157 	if (sf->op)
158 		return seq_lseek(file, off, origin);
159 	return default_llseek(file, off, origin);
160 }
161 
162 static const struct file_operations pstore_file_operations = {
163 	.open		= pstore_file_open,
164 	.read		= pstore_file_read,
165 	.llseek		= pstore_file_llseek,
166 	.release	= seq_release,
167 };
168 
169 /*
170  * When a file is unlinked from our file system we call the
171  * platform driver to erase the record from persistent store.
172  */
173 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
174 {
175 	struct pstore_private *p = dentry->d_inode->i_private;
176 
177 	if (p->psi->erase)
178 		p->psi->erase(p->type, p->id, p->psi);
179 
180 	return simple_unlink(dir, dentry);
181 }
182 
183 static void pstore_evict_inode(struct inode *inode)
184 {
185 	struct pstore_private	*p = inode->i_private;
186 	unsigned long		flags;
187 
188 	clear_inode(inode);
189 	if (p) {
190 		spin_lock_irqsave(&allpstore_lock, flags);
191 		list_del(&p->list);
192 		spin_unlock_irqrestore(&allpstore_lock, flags);
193 		kfree(p);
194 	}
195 }
196 
197 static const struct inode_operations pstore_dir_inode_operations = {
198 	.lookup		= simple_lookup,
199 	.unlink		= pstore_unlink,
200 };
201 
202 static struct inode *pstore_get_inode(struct super_block *sb)
203 {
204 	struct inode *inode = new_inode(sb);
205 	if (inode) {
206 		inode->i_ino = get_next_ino();
207 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
208 	}
209 	return inode;
210 }
211 
212 enum {
213 	Opt_kmsg_bytes, Opt_err
214 };
215 
216 static const match_table_t tokens = {
217 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
218 	{Opt_err, NULL}
219 };
220 
221 static void parse_options(char *options)
222 {
223 	char		*p;
224 	substring_t	args[MAX_OPT_ARGS];
225 	int		option;
226 
227 	if (!options)
228 		return;
229 
230 	while ((p = strsep(&options, ",")) != NULL) {
231 		int token;
232 
233 		if (!*p)
234 			continue;
235 
236 		token = match_token(p, tokens, args);
237 		switch (token) {
238 		case Opt_kmsg_bytes:
239 			if (!match_int(&args[0], &option))
240 				pstore_set_kmsg_bytes(option);
241 			break;
242 		}
243 	}
244 }
245 
246 static int pstore_remount(struct super_block *sb, int *flags, char *data)
247 {
248 	parse_options(data);
249 
250 	return 0;
251 }
252 
253 static const struct super_operations pstore_ops = {
254 	.statfs		= simple_statfs,
255 	.drop_inode	= generic_delete_inode,
256 	.evict_inode	= pstore_evict_inode,
257 	.remount_fs	= pstore_remount,
258 	.show_options	= generic_show_options,
259 };
260 
261 static struct super_block *pstore_sb;
262 
263 int pstore_is_mounted(void)
264 {
265 	return pstore_sb != NULL;
266 }
267 
268 /*
269  * Make a regular file in the root directory of our file system.
270  * Load it up with "size" bytes of data from "buf".
271  * Set the mtime & ctime to the date that this record was originally stored.
272  */
273 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
274 		  char *data, size_t size, struct timespec time,
275 		  struct pstore_info *psi)
276 {
277 	struct dentry		*root = pstore_sb->s_root;
278 	struct dentry		*dentry;
279 	struct inode		*inode;
280 	int			rc = 0;
281 	char			name[PSTORE_NAMELEN];
282 	struct pstore_private	*private, *pos;
283 	unsigned long		flags;
284 
285 	spin_lock_irqsave(&allpstore_lock, flags);
286 	list_for_each_entry(pos, &allpstore, list) {
287 		if (pos->type == type &&
288 		    pos->id == id &&
289 		    pos->psi == psi) {
290 			rc = -EEXIST;
291 			break;
292 		}
293 	}
294 	spin_unlock_irqrestore(&allpstore_lock, flags);
295 	if (rc)
296 		return rc;
297 
298 	rc = -ENOMEM;
299 	inode = pstore_get_inode(pstore_sb);
300 	if (!inode)
301 		goto fail;
302 	inode->i_mode = S_IFREG | 0444;
303 	inode->i_fop = &pstore_file_operations;
304 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
305 	if (!private)
306 		goto fail_alloc;
307 	private->type = type;
308 	private->id = id;
309 	private->psi = psi;
310 
311 	switch (type) {
312 	case PSTORE_TYPE_DMESG:
313 		sprintf(name, "dmesg-%s-%lld", psname, id);
314 		break;
315 	case PSTORE_TYPE_CONSOLE:
316 		sprintf(name, "console-%s", psname);
317 		break;
318 	case PSTORE_TYPE_FTRACE:
319 		sprintf(name, "ftrace-%s", psname);
320 		break;
321 	case PSTORE_TYPE_MCE:
322 		sprintf(name, "mce-%s-%lld", psname, id);
323 		break;
324 	case PSTORE_TYPE_UNKNOWN:
325 		sprintf(name, "unknown-%s-%lld", psname, id);
326 		break;
327 	default:
328 		sprintf(name, "type%d-%s-%lld", type, psname, id);
329 		break;
330 	}
331 
332 	mutex_lock(&root->d_inode->i_mutex);
333 
334 	rc = -ENOSPC;
335 	dentry = d_alloc_name(root, name);
336 	if (IS_ERR(dentry))
337 		goto fail_lockedalloc;
338 
339 	memcpy(private->data, data, size);
340 	inode->i_size = private->size = size;
341 
342 	inode->i_private = private;
343 
344 	if (time.tv_sec)
345 		inode->i_mtime = inode->i_ctime = time;
346 
347 	d_add(dentry, inode);
348 
349 	spin_lock_irqsave(&allpstore_lock, flags);
350 	list_add(&private->list, &allpstore);
351 	spin_unlock_irqrestore(&allpstore_lock, flags);
352 
353 	mutex_unlock(&root->d_inode->i_mutex);
354 
355 	return 0;
356 
357 fail_lockedalloc:
358 	mutex_unlock(&root->d_inode->i_mutex);
359 	kfree(private);
360 fail_alloc:
361 	iput(inode);
362 
363 fail:
364 	return rc;
365 }
366 
367 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
368 {
369 	struct inode *inode;
370 
371 	save_mount_options(sb, data);
372 
373 	pstore_sb = sb;
374 
375 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
376 	sb->s_blocksize		= PAGE_CACHE_SIZE;
377 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
378 	sb->s_magic		= PSTOREFS_MAGIC;
379 	sb->s_op		= &pstore_ops;
380 	sb->s_time_gran		= 1;
381 
382 	parse_options(data);
383 
384 	inode = pstore_get_inode(sb);
385 	if (inode) {
386 		inode->i_mode = S_IFDIR | 0755;
387 		inode->i_op = &pstore_dir_inode_operations;
388 		inode->i_fop = &simple_dir_operations;
389 		inc_nlink(inode);
390 	}
391 	sb->s_root = d_make_root(inode);
392 	if (!sb->s_root)
393 		return -ENOMEM;
394 
395 	pstore_get_records(0);
396 
397 	return 0;
398 }
399 
400 static struct dentry *pstore_mount(struct file_system_type *fs_type,
401 	int flags, const char *dev_name, void *data)
402 {
403 	return mount_single(fs_type, flags, data, pstore_fill_super);
404 }
405 
406 static void pstore_kill_sb(struct super_block *sb)
407 {
408 	kill_litter_super(sb);
409 	pstore_sb = NULL;
410 }
411 
412 static struct file_system_type pstore_fs_type = {
413 	.name		= "pstore",
414 	.mount		= pstore_mount,
415 	.kill_sb	= pstore_kill_sb,
416 };
417 
418 static int __init init_pstore_fs(void)
419 {
420 	return register_filesystem(&pstore_fs_type);
421 }
422 module_init(init_pstore_fs)
423 
424 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
425 MODULE_LICENSE("GPL");
426