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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, "%d %08lx  %08lx  %pf <- %pF\n",
111                 pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
112                 (void *)rec->ip, (void *)rec->parent_ip);
113 
114         return 0;
115 }
116 
117 static const struct seq_operations pstore_ftrace_seq_ops = {
118         .start  = pstore_ftrace_seq_start,
119         .next   = pstore_ftrace_seq_next,
120         .stop   = pstore_ftrace_seq_stop,
121         .show   = pstore_ftrace_seq_show,
122 };
123 
124 static int pstore_check_syslog_permissions(struct pstore_private *ps)
125 {
126         switch (ps->type) {
127         case PSTORE_TYPE_DMESG:
128         case PSTORE_TYPE_CONSOLE:
129                 return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
130                         SYSLOG_FROM_READER);
131         default:
132                 return 0;
133         }
134 }
135 
136 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
137                                                 size_t count, loff_t *ppos)
138 {
139         struct seq_file *sf = file->private_data;
140         struct pstore_private *ps = sf->private;
141 
142         if (ps->type == PSTORE_TYPE_FTRACE)
143                 return seq_read(file, userbuf, count, ppos);
144         return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
145 }
146 
147 static int pstore_file_open(struct inode *inode, struct file *file)
148 {
149         struct pstore_private *ps = inode->i_private;
150         struct seq_file *sf;
151         int err;
152         const struct seq_operations *sops = NULL;
153 
154         err = pstore_check_syslog_permissions(ps);
155         if (err)
156                 return err;
157 
158         if (ps->type == PSTORE_TYPE_FTRACE)
159                 sops = &pstore_ftrace_seq_ops;
160 
161         err = seq_open(file, sops);
162         if (err < 0)
163                 return err;
164 
165         sf = file->private_data;
166         sf->private = ps;
167 
168         return 0;
169 }
170 
171 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
172 {
173         struct seq_file *sf = file->private_data;
174 
175         if (sf->op)
176                 return seq_lseek(file, off, whence);
177         return default_llseek(file, off, whence);
178 }
179 
180 static const struct file_operations pstore_file_operations = {
181         .open           = pstore_file_open,
182         .read           = pstore_file_read,
183         .llseek         = pstore_file_llseek,
184         .release        = seq_release,
185 };
186 
187 /*
188  * When a file is unlinked from our file system we call the
189  * platform driver to erase the record from persistent store.
190  */
191 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
192 {
193         struct pstore_private *p = dentry->d_inode->i_private;
194         int err;
195 
196         err = pstore_check_syslog_permissions(p);
197         if (err)
198                 return err;
199 
200         if (p->psi->erase)
201                 p->psi->erase(p->type, p->id, p->count,
202                               dentry->d_inode->i_ctime, p->psi);
203         else
204                 return -EPERM;
205 
206         return simple_unlink(dir, dentry);
207 }
208 
209 static void pstore_evict_inode(struct inode *inode)
210 {
211         struct pstore_private   *p = inode->i_private;
212         unsigned long           flags;
213 
214         clear_inode(inode);
215         if (p) {
216                 spin_lock_irqsave(&allpstore_lock, flags);
217                 list_del(&p->list);
218                 spin_unlock_irqrestore(&allpstore_lock, flags);
219                 kfree(p);
220         }
221 }
222 
223 static const struct inode_operations pstore_dir_inode_operations = {
224         .lookup         = simple_lookup,
225         .unlink         = pstore_unlink,
226 };
227 
228 static struct inode *pstore_get_inode(struct super_block *sb)
229 {
230         struct inode *inode = new_inode(sb);
231         if (inode) {
232                 inode->i_ino = get_next_ino();
233                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
234         }
235         return inode;
236 }
237 
238 enum {
239         Opt_kmsg_bytes, Opt_err
240 };
241 
242 static const match_table_t tokens = {
243         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
244         {Opt_err, NULL}
245 };
246 
247 static void parse_options(char *options)
248 {
249         char            *p;
250         substring_t     args[MAX_OPT_ARGS];
251         int             option;
252 
253         if (!options)
254                 return;
255 
256         while ((p = strsep(&options, ",")) != NULL) {
257                 int token;
258 
259                 if (!*p)
260                         continue;
261 
262                 token = match_token(p, tokens, args);
263                 switch (token) {
264                 case Opt_kmsg_bytes:
265                         if (!match_int(&args[0], &option))
266                                 pstore_set_kmsg_bytes(option);
267                         break;
268                 }
269         }
270 }
271 
272 static int pstore_remount(struct super_block *sb, int *flags, char *data)
273 {
274         sync_filesystem(sb);
275         parse_options(data);
276 
277         return 0;
278 }
279 
280 static const struct super_operations pstore_ops = {
281         .statfs         = simple_statfs,
282         .drop_inode     = generic_delete_inode,
283         .evict_inode    = pstore_evict_inode,
284         .remount_fs     = pstore_remount,
285         .show_options   = generic_show_options,
286 };
287 
288 static struct super_block *pstore_sb;
289 
290 int pstore_is_mounted(void)
291 {
292         return pstore_sb != NULL;
293 }
294 
295 /*
296  * Make a regular file in the root directory of our file system.
297  * Load it up with "size" bytes of data from "buf".
298  * Set the mtime & ctime to the date that this record was originally stored.
299  */
300 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
301                   char *data, bool compressed, size_t size,
302                   struct timespec time, struct pstore_info *psi)
303 {
304         struct dentry           *root = pstore_sb->s_root;
305         struct dentry           *dentry;
306         struct inode            *inode;
307         int                     rc = 0;
308         char                    name[PSTORE_NAMELEN];
309         struct pstore_private   *private, *pos;
310         unsigned long           flags;
311 
312         spin_lock_irqsave(&allpstore_lock, flags);
313         list_for_each_entry(pos, &allpstore, list) {
314                 if (pos->type == type &&
315                     pos->id == id &&
316                     pos->psi == psi) {
317                         rc = -EEXIST;
318                         break;
319                 }
320         }
321         spin_unlock_irqrestore(&allpstore_lock, flags);
322         if (rc)
323                 return rc;
324 
325         rc = -ENOMEM;
326         inode = pstore_get_inode(pstore_sb);
327         if (!inode)
328                 goto fail;
329         inode->i_mode = S_IFREG | 0444;
330         inode->i_fop = &pstore_file_operations;
331         private = kmalloc(sizeof *private + size, GFP_KERNEL);
332         if (!private)
333                 goto fail_alloc;
334         private->type = type;
335         private->id = id;
336         private->count = count;
337         private->psi = psi;
338 
339         switch (type) {
340         case PSTORE_TYPE_DMESG:
341                 scnprintf(name, sizeof(name), "dmesg-%s-%lld%s",
342                           psname, id, compressed ? ".enc.z" : "");
343                 break;
344         case PSTORE_TYPE_CONSOLE:
345                 scnprintf(name, sizeof(name), "console-%s-%lld", psname, id);
346                 break;
347         case PSTORE_TYPE_FTRACE:
348                 scnprintf(name, sizeof(name), "ftrace-%s-%lld", psname, id);
349                 break;
350         case PSTORE_TYPE_MCE:
351                 scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
352                 break;
353         case PSTORE_TYPE_PPC_RTAS:
354                 scnprintf(name, sizeof(name), "rtas-%s-%lld", psname, id);
355                 break;
356         case PSTORE_TYPE_PPC_OF:
357                 scnprintf(name, sizeof(name), "powerpc-ofw-%s-%lld",
358                           psname, id);
359                 break;
360         case PSTORE_TYPE_PPC_COMMON:
361                 scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
362                           psname, id);
363                 break;
364         case PSTORE_TYPE_PMSG:
365                 scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
366                 break;
367         case PSTORE_TYPE_UNKNOWN:
368                 scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
369                 break;
370         default:
371                 scnprintf(name, sizeof(name), "type%d-%s-%lld",
372                           type, psname, id);
373                 break;
374         }
375 
376         mutex_lock(&root->d_inode->i_mutex);
377 
378         dentry = d_alloc_name(root, name);
379         if (!dentry)
380                 goto fail_lockedalloc;
381 
382         memcpy(private->data, data, size);
383         inode->i_size = private->size = size;
384 
385         inode->i_private = private;
386 
387         if (time.tv_sec)
388                 inode->i_mtime = inode->i_ctime = time;
389 
390         d_add(dentry, inode);
391 
392         spin_lock_irqsave(&allpstore_lock, flags);
393         list_add(&private->list, &allpstore);
394         spin_unlock_irqrestore(&allpstore_lock, flags);
395 
396         mutex_unlock(&root->d_inode->i_mutex);
397 
398         return 0;
399 
400 fail_lockedalloc:
401         mutex_unlock(&root->d_inode->i_mutex);
402         kfree(private);
403 fail_alloc:
404         iput(inode);
405 
406 fail:
407         return rc;
408 }
409 
410 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
411 {
412         struct inode *inode;
413 
414         save_mount_options(sb, data);
415 
416         pstore_sb = sb;
417 
418         sb->s_maxbytes          = MAX_LFS_FILESIZE;
419         sb->s_blocksize         = PAGE_CACHE_SIZE;
420         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
421         sb->s_magic             = PSTOREFS_MAGIC;
422         sb->s_op                = &pstore_ops;
423         sb->s_time_gran         = 1;
424 
425         parse_options(data);
426 
427         inode = pstore_get_inode(sb);
428         if (inode) {
429                 inode->i_mode = S_IFDIR | 0755;
430                 inode->i_op = &pstore_dir_inode_operations;
431                 inode->i_fop = &simple_dir_operations;
432                 inc_nlink(inode);
433         }
434         sb->s_root = d_make_root(inode);
435         if (!sb->s_root)
436                 return -ENOMEM;
437 
438         pstore_get_records(0);
439 
440         return 0;
441 }
442 
443 static struct dentry *pstore_mount(struct file_system_type *fs_type,
444         int flags, const char *dev_name, void *data)
445 {
446         return mount_single(fs_type, flags, data, pstore_fill_super);
447 }
448 
449 static void pstore_kill_sb(struct super_block *sb)
450 {
451         kill_litter_super(sb);
452         pstore_sb = NULL;
453 }
454 
455 static struct file_system_type pstore_fs_type = {
456         .name           = "pstore",
457         .mount          = pstore_mount,
458         .kill_sb        = pstore_kill_sb,
459 };
460 
461 static struct kobject *pstore_kobj;
462 
463 static int __init init_pstore_fs(void)
464 {
465         int err = 0;
466 
467         /* Create a convenient mount point for people to access pstore */
468         pstore_kobj = kobject_create_and_add("pstore", fs_kobj);
469         if (!pstore_kobj) {
470                 err = -ENOMEM;
471                 goto out;
472         }
473 
474         err = register_filesystem(&pstore_fs_type);
475         if (err < 0)
476                 kobject_put(pstore_kobj);
477 
478 out:
479         return err;
480 }
481 module_init(init_pstore_fs)
482 
483 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
484 MODULE_LICENSE("GPL");
485 

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