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Linux/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 #include <linux/syslog.h>
 40 
 41 #include "internal.h"
 42 
 43 #define PSTORE_NAMELEN  64
 44 
 45 static DEFINE_SPINLOCK(allpstore_lock);
 46 static LIST_HEAD(allpstore);
 47 
 48 struct pstore_private {
 49         struct list_head list;
 50         struct pstore_info *psi;
 51         enum pstore_type_id type;
 52         u64     id;
 53         int     count;
 54         ssize_t size;
 55         char    data[];
 56 };
 57 
 58 struct pstore_ftrace_seq_data {
 59         const void *ptr;
 60         size_t off;
 61         size_t size;
 62 };
 63 
 64 #define REC_SIZE sizeof(struct pstore_ftrace_record)
 65 
 66 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
 67 {
 68         struct pstore_private *ps = s->private;
 69         struct pstore_ftrace_seq_data *data;
 70 
 71         data = kzalloc(sizeof(*data), GFP_KERNEL);
 72         if (!data)
 73                 return NULL;
 74 
 75         data->off = ps->size % REC_SIZE;
 76         data->off += *pos * REC_SIZE;
 77         if (data->off + REC_SIZE > ps->size) {
 78                 kfree(data);
 79                 return NULL;
 80         }
 81 
 82         return data;
 83 
 84 }
 85 
 86 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
 87 {
 88         kfree(v);
 89 }
 90 
 91 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
 92 {
 93         struct pstore_private *ps = s->private;
 94         struct pstore_ftrace_seq_data *data = v;
 95 
 96         data->off += REC_SIZE;
 97         if (data->off + REC_SIZE > ps->size)
 98                 return NULL;
 99 
100         (*pos)++;
101         return data;
102 }
103 
104 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
105 {
106         struct pstore_private *ps = s->private;
107         struct pstore_ftrace_seq_data *data = v;
108         struct pstore_ftrace_record *rec = (void *)(ps->data + data->off);
109 
110         seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %pf <- %pF\n",
111                    pstore_ftrace_decode_cpu(rec),
112                    pstore_ftrace_read_timestamp(rec),
113                    rec->ip, rec->parent_ip, (void *)rec->ip,
114                    (void *)rec->parent_ip);
115 
116         return 0;
117 }
118 
119 static const struct seq_operations pstore_ftrace_seq_ops = {
120         .start  = pstore_ftrace_seq_start,
121         .next   = pstore_ftrace_seq_next,
122         .stop   = pstore_ftrace_seq_stop,
123         .show   = pstore_ftrace_seq_show,
124 };
125 
126 static int pstore_check_syslog_permissions(struct pstore_private *ps)
127 {
128         switch (ps->type) {
129         case PSTORE_TYPE_DMESG:
130         case PSTORE_TYPE_CONSOLE:
131                 return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
132                         SYSLOG_FROM_READER);
133         default:
134                 return 0;
135         }
136 }
137 
138 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
139                                                 size_t count, loff_t *ppos)
140 {
141         struct seq_file *sf = file->private_data;
142         struct pstore_private *ps = sf->private;
143 
144         if (ps->type == PSTORE_TYPE_FTRACE)
145                 return seq_read(file, userbuf, count, ppos);
146         return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->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         err = pstore_check_syslog_permissions(ps);
157         if (err)
158                 return err;
159 
160         if (ps->type == PSTORE_TYPE_FTRACE)
161                 sops = &pstore_ftrace_seq_ops;
162 
163         err = seq_open(file, sops);
164         if (err < 0)
165                 return err;
166 
167         sf = file->private_data;
168         sf->private = ps;
169 
170         return 0;
171 }
172 
173 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
174 {
175         struct seq_file *sf = file->private_data;
176 
177         if (sf->op)
178                 return seq_lseek(file, off, whence);
179         return default_llseek(file, off, whence);
180 }
181 
182 static const struct file_operations pstore_file_operations = {
183         .open           = pstore_file_open,
184         .read           = pstore_file_read,
185         .llseek         = pstore_file_llseek,
186         .release        = seq_release,
187 };
188 
189 /*
190  * When a file is unlinked from our file system we call the
191  * platform driver to erase the record from persistent store.
192  */
193 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
194 {
195         struct pstore_private *p = d_inode(dentry)->i_private;
196         int err;
197 
198         err = pstore_check_syslog_permissions(p);
199         if (err)
200                 return err;
201 
202         if (p->psi->erase) {
203                 mutex_lock(&p->psi->read_mutex);
204                 p->psi->erase(p->type, p->id, p->count,
205                               d_inode(dentry)->i_ctime, p->psi);
206                 mutex_unlock(&p->psi->read_mutex);
207         } else {
208                 return -EPERM;
209         }
210 
211         return simple_unlink(dir, dentry);
212 }
213 
214 static void pstore_evict_inode(struct inode *inode)
215 {
216         struct pstore_private   *p = inode->i_private;
217         unsigned long           flags;
218 
219         clear_inode(inode);
220         if (p) {
221                 spin_lock_irqsave(&allpstore_lock, flags);
222                 list_del(&p->list);
223                 spin_unlock_irqrestore(&allpstore_lock, flags);
224                 kfree(p);
225         }
226 }
227 
228 static const struct inode_operations pstore_dir_inode_operations = {
229         .lookup         = simple_lookup,
230         .unlink         = pstore_unlink,
231 };
232 
233 static struct inode *pstore_get_inode(struct super_block *sb)
234 {
235         struct inode *inode = new_inode(sb);
236         if (inode) {
237                 inode->i_ino = get_next_ino();
238                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
239         }
240         return inode;
241 }
242 
243 enum {
244         Opt_kmsg_bytes, Opt_err
245 };
246 
247 static const match_table_t tokens = {
248         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
249         {Opt_err, NULL}
250 };
251 
252 static void parse_options(char *options)
253 {
254         char            *p;
255         substring_t     args[MAX_OPT_ARGS];
256         int             option;
257 
258         if (!options)
259                 return;
260 
261         while ((p = strsep(&options, ",")) != NULL) {
262                 int token;
263 
264                 if (!*p)
265                         continue;
266 
267                 token = match_token(p, tokens, args);
268                 switch (token) {
269                 case Opt_kmsg_bytes:
270                         if (!match_int(&args[0], &option))
271                                 pstore_set_kmsg_bytes(option);
272                         break;
273                 }
274         }
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   = generic_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(enum pstore_type_id type, char *psname, u64 id, int count,
306                   char *data, bool compressed, size_t size,
307                   struct timespec time, struct pstore_info *psi)
308 {
309         struct dentry           *root = pstore_sb->s_root;
310         struct dentry           *dentry;
311         struct inode            *inode;
312         int                     rc = 0;
313         char                    name[PSTORE_NAMELEN];
314         struct pstore_private   *private, *pos;
315         unsigned long           flags;
316 
317         spin_lock_irqsave(&allpstore_lock, flags);
318         list_for_each_entry(pos, &allpstore, list) {
319                 if (pos->type == type &&
320                     pos->id == id &&
321                     pos->psi == 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(pstore_sb);
332         if (!inode)
333                 goto fail;
334         inode->i_mode = S_IFREG | 0444;
335         inode->i_fop = &pstore_file_operations;
336         private = kmalloc(sizeof *private + size, GFP_KERNEL);
337         if (!private)
338                 goto fail_alloc;
339         private->type = type;
340         private->id = id;
341         private->count = count;
342         private->psi = psi;
343 
344         switch (type) {
345         case PSTORE_TYPE_DMESG:
346                 scnprintf(name, sizeof(name), "dmesg-%s-%lld%s",
347                           psname, id, compressed ? ".enc.z" : "");
348                 break;
349         case PSTORE_TYPE_CONSOLE:
350                 scnprintf(name, sizeof(name), "console-%s-%lld", psname, id);
351                 break;
352         case PSTORE_TYPE_FTRACE:
353                 scnprintf(name, sizeof(name), "ftrace-%s-%lld", psname, id);
354                 break;
355         case PSTORE_TYPE_MCE:
356                 scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
357                 break;
358         case PSTORE_TYPE_PPC_RTAS:
359                 scnprintf(name, sizeof(name), "rtas-%s-%lld", psname, id);
360                 break;
361         case PSTORE_TYPE_PPC_OF:
362                 scnprintf(name, sizeof(name), "powerpc-ofw-%s-%lld",
363                           psname, id);
364                 break;
365         case PSTORE_TYPE_PPC_COMMON:
366                 scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
367                           psname, id);
368                 break;
369         case PSTORE_TYPE_PMSG:
370                 scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
371                 break;
372         case PSTORE_TYPE_PPC_OPAL:
373                 sprintf(name, "powerpc-opal-%s-%lld", psname, id);
374                 break;
375         case PSTORE_TYPE_UNKNOWN:
376                 scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
377                 break;
378         default:
379                 scnprintf(name, sizeof(name), "type%d-%s-%lld",
380                           type, psname, id);
381                 break;
382         }
383 
384         inode_lock(d_inode(root));
385 
386         dentry = d_alloc_name(root, name);
387         if (!dentry)
388                 goto fail_lockedalloc;
389 
390         memcpy(private->data, data, size);
391         inode->i_size = private->size = size;
392 
393         inode->i_private = private;
394 
395         if (time.tv_sec)
396                 inode->i_mtime = inode->i_ctime = time;
397 
398         d_add(dentry, inode);
399 
400         spin_lock_irqsave(&allpstore_lock, flags);
401         list_add(&private->list, &allpstore);
402         spin_unlock_irqrestore(&allpstore_lock, flags);
403 
404         inode_unlock(d_inode(root));
405 
406         return 0;
407 
408 fail_lockedalloc:
409         inode_unlock(d_inode(root));
410         kfree(private);
411 fail_alloc:
412         iput(inode);
413 
414 fail:
415         return rc;
416 }
417 
418 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
419 {
420         struct inode *inode;
421 
422         save_mount_options(sb, data);
423 
424         pstore_sb = sb;
425 
426         sb->s_maxbytes          = MAX_LFS_FILESIZE;
427         sb->s_blocksize         = PAGE_SIZE;
428         sb->s_blocksize_bits    = PAGE_SHIFT;
429         sb->s_magic             = PSTOREFS_MAGIC;
430         sb->s_op                = &pstore_ops;
431         sb->s_time_gran         = 1;
432 
433         parse_options(data);
434 
435         inode = pstore_get_inode(sb);
436         if (inode) {
437                 inode->i_mode = S_IFDIR | 0755;
438                 inode->i_op = &pstore_dir_inode_operations;
439                 inode->i_fop = &simple_dir_operations;
440                 inc_nlink(inode);
441         }
442         sb->s_root = d_make_root(inode);
443         if (!sb->s_root)
444                 return -ENOMEM;
445 
446         pstore_get_records(0);
447 
448         return 0;
449 }
450 
451 static struct dentry *pstore_mount(struct file_system_type *fs_type,
452         int flags, const char *dev_name, void *data)
453 {
454         return mount_single(fs_type, flags, data, pstore_fill_super);
455 }
456 
457 static void pstore_kill_sb(struct super_block *sb)
458 {
459         kill_litter_super(sb);
460         pstore_sb = NULL;
461 }
462 
463 static struct file_system_type pstore_fs_type = {
464         .owner          = THIS_MODULE,
465         .name           = "pstore",
466         .mount          = pstore_mount,
467         .kill_sb        = pstore_kill_sb,
468 };
469 
470 static int __init init_pstore_fs(void)
471 {
472         int err;
473 
474         /* Create a convenient mount point for people to access pstore */
475         err = sysfs_create_mount_point(fs_kobj, "pstore");
476         if (err)
477                 goto out;
478 
479         err = register_filesystem(&pstore_fs_type);
480         if (err < 0)
481                 sysfs_remove_mount_point(fs_kobj, "pstore");
482 
483 out:
484         return err;
485 }
486 module_init(init_pstore_fs)
487 
488 static void __exit exit_pstore_fs(void)
489 {
490         unregister_filesystem(&pstore_fs_type);
491         sysfs_remove_mount_point(fs_kobj, "pstore");
492 }
493 module_exit(exit_pstore_fs)
494 
495 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
496 MODULE_LICENSE("GPL");
497 

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