GNU Linux-libre 4.19.211-gnu1
[releases.git] / fs / pstore / inode.c
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         (*pos)++;
103         data->off += REC_SIZE;
104         if (data->off + REC_SIZE > ps->total_size)
105                 return NULL;
106
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         if (!data)
117                 return 0;
118
119         rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
120
121         seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %pf <- %pF\n",
122                    pstore_ftrace_decode_cpu(rec),
123                    pstore_ftrace_read_timestamp(rec),
124                    rec->ip, rec->parent_ip, (void *)rec->ip,
125                    (void *)rec->parent_ip);
126
127         return 0;
128 }
129
130 static const struct seq_operations pstore_ftrace_seq_ops = {
131         .start  = pstore_ftrace_seq_start,
132         .next   = pstore_ftrace_seq_next,
133         .stop   = pstore_ftrace_seq_stop,
134         .show   = pstore_ftrace_seq_show,
135 };
136
137 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
138                                                 size_t count, loff_t *ppos)
139 {
140         struct seq_file *sf = file->private_data;
141         struct pstore_private *ps = sf->private;
142
143         if (ps->record->type == PSTORE_TYPE_FTRACE)
144                 return seq_read(file, userbuf, count, ppos);
145         return simple_read_from_buffer(userbuf, count, ppos,
146                                        ps->record->buf, ps->total_size);
147 }
148
149 static int pstore_file_open(struct inode *inode, struct file *file)
150 {
151         struct pstore_private *ps = inode->i_private;
152         struct seq_file *sf;
153         int err;
154         const struct seq_operations *sops = NULL;
155
156         if (ps->record->type == PSTORE_TYPE_FTRACE)
157                 sops = &pstore_ftrace_seq_ops;
158
159         err = seq_open(file, sops);
160         if (err < 0)
161                 return err;
162
163         sf = file->private_data;
164         sf->private = ps;
165
166         return 0;
167 }
168
169 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
170 {
171         struct seq_file *sf = file->private_data;
172
173         if (sf->op)
174                 return seq_lseek(file, off, whence);
175         return default_llseek(file, off, whence);
176 }
177
178 static const struct file_operations pstore_file_operations = {
179         .open           = pstore_file_open,
180         .read           = pstore_file_read,
181         .llseek         = pstore_file_llseek,
182         .release        = seq_release,
183 };
184
185 /*
186  * When a file is unlinked from our file system we call the
187  * platform driver to erase the record from persistent store.
188  */
189 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
190 {
191         struct pstore_private *p = d_inode(dentry)->i_private;
192         struct pstore_record *record = p->record;
193
194         if (!record->psi->erase)
195                 return -EPERM;
196
197         mutex_lock(&record->psi->read_mutex);
198         record->psi->erase(record);
199         mutex_unlock(&record->psi->read_mutex);
200
201         return simple_unlink(dir, dentry);
202 }
203
204 static void pstore_evict_inode(struct inode *inode)
205 {
206         struct pstore_private   *p = inode->i_private;
207         unsigned long           flags;
208
209         clear_inode(inode);
210         if (p) {
211                 spin_lock_irqsave(&allpstore_lock, flags);
212                 list_del(&p->list);
213                 spin_unlock_irqrestore(&allpstore_lock, flags);
214                 free_pstore_private(p);
215         }
216 }
217
218 static const struct inode_operations pstore_dir_inode_operations = {
219         .lookup         = simple_lookup,
220         .unlink         = pstore_unlink,
221 };
222
223 static struct inode *pstore_get_inode(struct super_block *sb)
224 {
225         struct inode *inode = new_inode(sb);
226         if (inode) {
227                 inode->i_ino = get_next_ino();
228                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
229         }
230         return inode;
231 }
232
233 enum {
234         Opt_kmsg_bytes, Opt_err
235 };
236
237 static const match_table_t tokens = {
238         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
239         {Opt_err, NULL}
240 };
241
242 static void parse_options(char *options)
243 {
244         char            *p;
245         substring_t     args[MAX_OPT_ARGS];
246         int             option;
247
248         if (!options)
249                 return;
250
251         while ((p = strsep(&options, ",")) != NULL) {
252                 int token;
253
254                 if (!*p)
255                         continue;
256
257                 token = match_token(p, tokens, args);
258                 switch (token) {
259                 case Opt_kmsg_bytes:
260                         if (!match_int(&args[0], &option))
261                                 pstore_set_kmsg_bytes(option);
262                         break;
263                 }
264         }
265 }
266
267 /*
268  * Display the mount options in /proc/mounts.
269  */
270 static int pstore_show_options(struct seq_file *m, struct dentry *root)
271 {
272         if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
273                 seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
274         return 0;
275 }
276
277 static int pstore_remount(struct super_block *sb, int *flags, char *data)
278 {
279         sync_filesystem(sb);
280         parse_options(data);
281
282         return 0;
283 }
284
285 static const struct super_operations pstore_ops = {
286         .statfs         = simple_statfs,
287         .drop_inode     = generic_delete_inode,
288         .evict_inode    = pstore_evict_inode,
289         .remount_fs     = pstore_remount,
290         .show_options   = pstore_show_options,
291 };
292
293 static struct super_block *pstore_sb;
294
295 bool pstore_is_mounted(void)
296 {
297         return pstore_sb != NULL;
298 }
299
300 /*
301  * Make a regular file in the root directory of our file system.
302  * Load it up with "size" bytes of data from "buf".
303  * Set the mtime & ctime to the date that this record was originally stored.
304  */
305 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
306 {
307         struct dentry           *dentry;
308         struct inode            *inode;
309         int                     rc = 0;
310         char                    name[PSTORE_NAMELEN];
311         struct pstore_private   *private, *pos;
312         unsigned long           flags;
313         size_t                  size = record->size + record->ecc_notice_size;
314
315         WARN_ON(!inode_is_locked(d_inode(root)));
316
317         spin_lock_irqsave(&allpstore_lock, flags);
318         list_for_each_entry(pos, &allpstore, list) {
319                 if (pos->record->type == record->type &&
320                     pos->record->id == record->id &&
321                     pos->record->psi == record->psi) {
322                         rc = -EEXIST;
323                         break;
324                 }
325         }
326         spin_unlock_irqrestore(&allpstore_lock, flags);
327         if (rc)
328                 return rc;
329
330         rc = -ENOMEM;
331         inode = pstore_get_inode(root->d_sb);
332         if (!inode)
333                 goto fail;
334         inode->i_mode = S_IFREG | 0444;
335         inode->i_fop = &pstore_file_operations;
336
337         switch (record->type) {
338         case PSTORE_TYPE_DMESG:
339                 scnprintf(name, sizeof(name), "dmesg-%s-%llu%s",
340                           record->psi->name, record->id,
341                           record->compressed ? ".enc.z" : "");
342                 break;
343         case PSTORE_TYPE_CONSOLE:
344                 scnprintf(name, sizeof(name), "console-%s-%llu",
345                           record->psi->name, record->id);
346                 break;
347         case PSTORE_TYPE_FTRACE:
348                 scnprintf(name, sizeof(name), "ftrace-%s-%llu",
349                           record->psi->name, record->id);
350                 break;
351         case PSTORE_TYPE_MCE:
352                 scnprintf(name, sizeof(name), "mce-%s-%llu",
353                           record->psi->name, record->id);
354                 break;
355         case PSTORE_TYPE_PPC_RTAS:
356                 scnprintf(name, sizeof(name), "rtas-%s-%llu",
357                           record->psi->name, record->id);
358                 break;
359         case PSTORE_TYPE_PPC_OF:
360                 scnprintf(name, sizeof(name), "powerpc-ofw-%s-%llu",
361                           record->psi->name, record->id);
362                 break;
363         case PSTORE_TYPE_PPC_COMMON:
364                 scnprintf(name, sizeof(name), "powerpc-common-%s-%llu",
365                           record->psi->name, record->id);
366                 break;
367         case PSTORE_TYPE_PMSG:
368                 scnprintf(name, sizeof(name), "pmsg-%s-%llu",
369                           record->psi->name, record->id);
370                 break;
371         case PSTORE_TYPE_PPC_OPAL:
372                 scnprintf(name, sizeof(name), "powerpc-opal-%s-%llu",
373                           record->psi->name, record->id);
374                 break;
375         case PSTORE_TYPE_UNKNOWN:
376                 scnprintf(name, sizeof(name), "unknown-%s-%llu",
377                           record->psi->name, record->id);
378                 break;
379         default:
380                 scnprintf(name, sizeof(name), "type%d-%s-%llu",
381                           record->type, record->psi->name, record->id);
382                 break;
383         }
384
385         private = kzalloc(sizeof(*private), GFP_KERNEL);
386         if (!private)
387                 goto fail_inode;
388
389         dentry = d_alloc_name(root, name);
390         if (!dentry)
391                 goto fail_private;
392
393         private->record = record;
394         inode->i_size = private->total_size = size;
395         inode->i_private = private;
396
397         if (record->time.tv_sec)
398                 inode->i_mtime = inode->i_ctime = record->time;
399
400         d_add(dentry, inode);
401
402         spin_lock_irqsave(&allpstore_lock, flags);
403         list_add(&private->list, &allpstore);
404         spin_unlock_irqrestore(&allpstore_lock, flags);
405
406         return 0;
407
408 fail_private:
409         free_pstore_private(private);
410 fail_inode:
411         iput(inode);
412
413 fail:
414         return rc;
415 }
416
417 /*
418  * Read all the records from the persistent store. Create
419  * files in our filesystem.  Don't warn about -EEXIST errors
420  * when we are re-scanning the backing store looking to add new
421  * error records.
422  */
423 void pstore_get_records(int quiet)
424 {
425         struct pstore_info *psi = psinfo;
426         struct dentry *root;
427
428         if (!psi || !pstore_sb)
429                 return;
430
431         root = pstore_sb->s_root;
432
433         inode_lock(d_inode(root));
434         pstore_get_backend_records(psi, root, quiet);
435         inode_unlock(d_inode(root));
436 }
437
438 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
439 {
440         struct inode *inode;
441
442         pstore_sb = sb;
443
444         sb->s_maxbytes          = MAX_LFS_FILESIZE;
445         sb->s_blocksize         = PAGE_SIZE;
446         sb->s_blocksize_bits    = PAGE_SHIFT;
447         sb->s_magic             = PSTOREFS_MAGIC;
448         sb->s_op                = &pstore_ops;
449         sb->s_time_gran         = 1;
450
451         parse_options(data);
452
453         inode = pstore_get_inode(sb);
454         if (inode) {
455                 inode->i_mode = S_IFDIR | 0750;
456                 inode->i_op = &pstore_dir_inode_operations;
457                 inode->i_fop = &simple_dir_operations;
458                 inc_nlink(inode);
459         }
460         sb->s_root = d_make_root(inode);
461         if (!sb->s_root)
462                 return -ENOMEM;
463
464         pstore_get_records(0);
465
466         return 0;
467 }
468
469 static struct dentry *pstore_mount(struct file_system_type *fs_type,
470         int flags, const char *dev_name, void *data)
471 {
472         return mount_single(fs_type, flags, data, pstore_fill_super);
473 }
474
475 static void pstore_kill_sb(struct super_block *sb)
476 {
477         kill_litter_super(sb);
478         pstore_sb = NULL;
479 }
480
481 static struct file_system_type pstore_fs_type = {
482         .owner          = THIS_MODULE,
483         .name           = "pstore",
484         .mount          = pstore_mount,
485         .kill_sb        = pstore_kill_sb,
486 };
487
488 int __init pstore_init_fs(void)
489 {
490         int err;
491
492         /* Create a convenient mount point for people to access pstore */
493         err = sysfs_create_mount_point(fs_kobj, "pstore");
494         if (err)
495                 goto out;
496
497         err = register_filesystem(&pstore_fs_type);
498         if (err < 0)
499                 sysfs_remove_mount_point(fs_kobj, "pstore");
500
501 out:
502         return err;
503 }
504
505 void __exit pstore_exit_fs(void)
506 {
507         unregister_filesystem(&pstore_fs_type);
508         sysfs_remove_mount_point(fs_kobj, "pstore");
509 }