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_record *record;
  51         size_t total_size;
  52 };
  53
  54 struct pstore_ftrace_seq_data {
  55         const void *ptr;
  56         size_t off;
  57         size_t size;
  58 };
  59
  60 #define REC_SIZE sizeof(struct pstore_ftrace_record)
  61
  62 static void free_pstore_private(struct pstore_private *private)
  63 {
  64         if (!private)
  65                 return;
  66         if (private->record) {
  67                 kfree(private->record->buf);
  68                 kfree(private->record);
  69         }
  70         kfree(private);
  71 }
  72
  73 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
  74 {
  75         struct pstore_private *ps = s->private;
  76         struct pstore_ftrace_seq_data *data;
  77
  78         data = kzalloc(sizeof(*data), GFP_KERNEL);
  79         if (!data)
  80                 return NULL;
  81
  82         data->off = ps->total_size % REC_SIZE;
  83         data->off += *pos * REC_SIZE;
  84         if (data->off + REC_SIZE > ps->total_size) {
  85                 kfree(data);
  86                 return NULL;
  87         }
  88
  89         return data;
  90
  91 }
  92
  93 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
  94 {
  95         kfree(v);
  96 }
  97
  98 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
  99 {
 100         struct pstore_private *ps = s->private;
 101         struct pstore_ftrace_seq_data *data = v;
 102
 103         data->off += REC_SIZE;
 104         if (data->off + REC_SIZE > ps->total_size)
 105                 return NULL;
 106
 107         (*pos)++;
 108         return data;
 109 }
 110
 111 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
 112 {
 113         struct pstore_private *ps = s->private;
 114         struct pstore_ftrace_seq_data *data = v;
 115         struct pstore_ftrace_record *rec;
 116
 117         rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
 118
 119         seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %pf <- %pF\n",
 120                    pstore_ftrace_decode_cpu(rec),
 121                    pstore_ftrace_read_timestamp(rec),
 122                    rec->ip, rec->parent_ip, (void *)rec->ip,
 123                    (void *)rec->parent_ip);
 124
 125         return 0;
 126 }
 127
 128 static const struct seq_operations pstore_ftrace_seq_ops = {
 129         .start  = pstore_ftrace_seq_start,
 130         .next   = pstore_ftrace_seq_next,
 131         .stop   = pstore_ftrace_seq_stop,
 132         .show   = pstore_ftrace_seq_show,
 133 };
 134
 135 static int pstore_check_syslog_permissions(struct pstore_private *ps)
 136 {
 137         switch (ps->record->type) {
 138         case PSTORE_TYPE_DMESG:
 139         case PSTORE_TYPE_CONSOLE:
 140                 return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
 141                         SYSLOG_FROM_READER);
 142         default:
 143                 return 0;
 144         }
 145 }
 146
 147 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
 148                                                 size_t count, loff_t *ppos)
 149 {
 150         struct seq_file *sf = file->private_data;
 151         struct pstore_private *ps = sf->private;
 152
 153         if (ps->record->type == PSTORE_TYPE_FTRACE)
 154                 return seq_read(file, userbuf, count, ppos);
 155         return simple_read_from_buffer(userbuf, count, ppos,
 156                                        ps->record->buf, ps->total_size);
 157 }
 158
 159 static int pstore_file_open(struct inode *inode, struct file *file)
 160 {
 161         struct pstore_private *ps = inode->i_private;
 162         struct seq_file *sf;
 163         int err;
 164         const struct seq_operations *sops = NULL;
 165
 166         err = pstore_check_syslog_permissions(ps);
 167         if (err)
 168                 return err;
 169
 170         if (ps->record->type == PSTORE_TYPE_FTRACE)
 171                 sops = &pstore_ftrace_seq_ops;
 172
 173         err = seq_open(file, sops);
 174         if (err < 0)
 175                 return err;
 176
 177         sf = file->private_data;
 178         sf->private = ps;
 179
 180         return 0;
 181 }
 182
 183 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
 184 {
 185         struct seq_file *sf = file->private_data;
 186
 187         if (sf->op)
 188                 return seq_lseek(file, off, whence);
 189         return default_llseek(file, off, whence);
 190 }
 191
 192 static const struct file_operations pstore_file_operations = {
 193         .open           = pstore_file_open,
 194         .read           = pstore_file_read,
 195         .llseek         = pstore_file_llseek,
 196         .release        = seq_release,
 197 };
 198
 199 /*
 200  * When a file is unlinked from our file system we call the
 201  * platform driver to erase the record from persistent store.
 202  */
 203 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 204 {
 205         struct pstore_private *p = d_inode(dentry)->i_private;
 206         struct pstore_record *record = p->record;
 207         int err;
 208
 209         err = pstore_check_syslog_permissions(p);
 210         if (err)
 211                 return err;
 212
 213         if (!record->psi->erase)
 214                 return -EPERM;
 215
 216         mutex_lock(&record->psi->read_mutex);
 217         record->psi->erase(record);
 218         mutex_unlock(&record->psi->read_mutex);
 219
 220         return simple_unlink(dir, dentry);
 221 }
 222
 223 static void pstore_evict_inode(struct inode *inode)
 224 {
 225         struct pstore_private   *p = inode->i_private;
 226         unsigned long           flags;
 227
 228         clear_inode(inode);
 229         if (p) {
 230                 spin_lock_irqsave(&allpstore_lock, flags);
 231                 list_del(&p->list);
 232                 spin_unlock_irqrestore(&allpstore_lock, flags);
 233                 free_pstore_private(p);
 234         }
 235 }
 236
 237 static const struct inode_operations pstore_dir_inode_operations = {
 238         .lookup         = simple_lookup,
 239         .unlink         = pstore_unlink,
 240 };
 241
 242 static struct inode *pstore_get_inode(struct super_block *sb)
 243 {
 244         struct inode *inode = new_inode(sb);
 245         if (inode) {
 246                 inode->i_ino = get_next_ino();
 247                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 248         }
 249         return inode;
 250 }
 251
 252 enum {
 253         Opt_kmsg_bytes, Opt_err
 254 };
 255
 256 static const match_table_t tokens = {
 257         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
 258         {Opt_err, NULL}
 259 };
 260
 261 static void parse_options(char *options)
 262 {
 263         char            *p;
 264         substring_t     args[MAX_OPT_ARGS];
 265         int             option;
 266
 267         if (!options)
 268                 return;
 269
 270         while ((p = strsep(&options, ",")) != NULL) {
 271                 int token;
 272
 273                 if (!*p)
 274                         continue;
 275
 276                 token = match_token(p, tokens, args);
 277                 switch (token) {
 278                 case Opt_kmsg_bytes:
 279                         if (!match_int(&args[0], &option))
 280                                 pstore_set_kmsg_bytes(option);
 281                         break;
 282                 }
 283         }
 284 }
 285
 286 /*
 287  * Display the mount options in /proc/mounts.
 288  */
 289 static int pstore_show_options(struct seq_file *m, struct dentry *root)
 290 {
 291         if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
 292                 seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
 293         return 0;
 294 }
 295
 296 static int pstore_remount(struct super_block *sb, int *flags, char *data)
 297 {
 298         sync_filesystem(sb);
 299         parse_options(data);
 300
 301         return 0;
 302 }
 303
 304 static const struct super_operations pstore_ops = {
 305         .statfs         = simple_statfs,
 306         .drop_inode     = generic_delete_inode,
 307         .evict_inode    = pstore_evict_inode,
 308         .remount_fs     = pstore_remount,
 309         .show_options   = pstore_show_options,
 310 };
 311
 312 static struct super_block *pstore_sb;
 313
 314 bool pstore_is_mounted(void)
 315 {
 316         return pstore_sb != NULL;
 317 }
 318
 319 /*
 320  * Make a regular file in the root directory of our file system.
 321  * Load it up with "size" bytes of data from "buf".
 322  * Set the mtime & ctime to the date that this record was originally stored.
 323  */
 324 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 325 {
 326         struct dentry           *dentry;
 327         struct inode            *inode;
 328         int                     rc = 0;
 329         char                    name[PSTORE_NAMELEN];
 330         struct pstore_private   *private, *pos;
 331         unsigned long           flags;
 332         size_t                  size = record->size + record->ecc_notice_size;
 333
 334         WARN_ON(!inode_is_locked(d_inode(root)));
 335
 336         spin_lock_irqsave(&allpstore_lock, flags);
 337         list_for_each_entry(pos, &allpstore, list) {
 338                 if (pos->record->type == record->type &&
 339                     pos->record->id == record->id &&
 340                     pos->record->psi == record->psi) {
 341                         rc = -EEXIST;
 342                         break;
 343                 }
 344         }
 345         spin_unlock_irqrestore(&allpstore_lock, flags);
 346         if (rc)
 347                 return rc;
 348
 349         rc = -ENOMEM;
 350         inode = pstore_get_inode(root->d_sb);
 351         if (!inode)
 352                 goto fail;
 353         inode->i_mode = S_IFREG | 0444;
 354         inode->i_fop = &pstore_file_operations;
 355         private = kzalloc(sizeof(*private), GFP_KERNEL);
 356         if (!private)
 357                 goto fail_alloc;
 358         private->record = record;
 359
 360         switch (record->type) {
 361         case PSTORE_TYPE_DMESG:
 362                 scnprintf(name, sizeof(name), "dmesg-%s-%llu%s",
 363                           record->psi->name, record->id,
 364                           record->compressed ? ".enc.z" : "");
 365                 break;
 366         case PSTORE_TYPE_CONSOLE:
 367                 scnprintf(name, sizeof(name), "console-%s-%llu",
 368                           record->psi->name, record->id);
 369                 break;
 370         case PSTORE_TYPE_FTRACE:
 371                 scnprintf(name, sizeof(name), "ftrace-%s-%llu",
 372                           record->psi->name, record->id);
 373                 break;
 374         case PSTORE_TYPE_MCE:
 375                 scnprintf(name, sizeof(name), "mce-%s-%llu",
 376                           record->psi->name, record->id);
 377                 break;
 378         case PSTORE_TYPE_PPC_RTAS:
 379                 scnprintf(name, sizeof(name), "rtas-%s-%llu",
 380                           record->psi->name, record->id);
 381                 break;
 382         case PSTORE_TYPE_PPC_OF:
 383                 scnprintf(name, sizeof(name), "powerpc-ofw-%s-%llu",
 384                           record->psi->name, record->id);
 385                 break;
 386         case PSTORE_TYPE_PPC_COMMON:
 387                 scnprintf(name, sizeof(name), "powerpc-common-%s-%llu",
 388                           record->psi->name, record->id);
 389                 break;
 390         case PSTORE_TYPE_PMSG:
 391                 scnprintf(name, sizeof(name), "pmsg-%s-%llu",
 392                           record->psi->name, record->id);
 393                 break;
 394         case PSTORE_TYPE_PPC_OPAL:
 395                 scnprintf(name, sizeof(name), "powerpc-opal-%s-%llu",
 396                           record->psi->name, record->id);
 397                 break;
 398         case PSTORE_TYPE_UNKNOWN:
 399                 scnprintf(name, sizeof(name), "unknown-%s-%llu",
 400                           record->psi->name, record->id);
 401                 break;
 402         default:
 403                 scnprintf(name, sizeof(name), "type%d-%s-%llu",
 404                           record->type, record->psi->name, record->id);
 405                 break;
 406         }
 407
 408         dentry = d_alloc_name(root, name);
 409         if (!dentry)
 410                 goto fail_private;
 411
 412         inode->i_size = private->total_size = size;
 413
 414         inode->i_private = private;
 415
 416         if (record->time.tv_sec)
 417                 inode->i_mtime = inode->i_ctime = record->time;
 418
 419         d_add(dentry, inode);
 420
 421         spin_lock_irqsave(&allpstore_lock, flags);
 422         list_add(&private->list, &allpstore);
 423         spin_unlock_irqrestore(&allpstore_lock, flags);
 424
 425         return 0;
 426
 427 fail_private:
 428         free_pstore_private(private);
 429 fail_alloc:
 430         iput(inode);
 431
 432 fail:
 433         return rc;
 434 }
 435
 436 /*
 437  * Read all the records from the persistent store. Create
 438  * files in our filesystem.  Don't warn about -EEXIST errors
 439  * when we are re-scanning the backing store looking to add new
 440  * error records.
 441  */
 442 void pstore_get_records(int quiet)
 443 {
 444         struct pstore_info *psi = psinfo;
 445         struct dentry *root;
 446
 447         if (!psi || !pstore_sb)
 448                 return;
 449
 450         root = pstore_sb->s_root;
 451
 452         inode_lock(d_inode(root));
 453         pstore_get_backend_records(psi, root, quiet);
 454         inode_unlock(d_inode(root));
 455 }
 456
 457 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 458 {
 459         struct inode *inode;
 460
 461         pstore_sb = sb;
 462
 463         sb->s_maxbytes          = MAX_LFS_FILESIZE;
 464         sb->s_blocksize         = PAGE_SIZE;
 465         sb->s_blocksize_bits    = PAGE_SHIFT;
 466         sb->s_magic             = PSTOREFS_MAGIC;
 467         sb->s_op                = &pstore_ops;
 468         sb->s_time_gran         = 1;
 469
 470         parse_options(data);
 471
 472         inode = pstore_get_inode(sb);
 473         if (inode) {
 474                 inode->i_mode = S_IFDIR | 0755;
 475                 inode->i_op = &pstore_dir_inode_operations;
 476                 inode->i_fop = &simple_dir_operations;
 477                 inc_nlink(inode);
 478         }
 479         sb->s_root = d_make_root(inode);
 480         if (!sb->s_root)
 481                 return -ENOMEM;
 482
 483         pstore_get_records(0);
 484
 485         return 0;
 486 }
 487
 488 static struct dentry *pstore_mount(struct file_system_type *fs_type,
 489         int flags, const char *dev_name, void *data)
 490 {
 491         return mount_single(fs_type, flags, data, pstore_fill_super);
 492 }
 493
 494 static void pstore_kill_sb(struct super_block *sb)
 495 {
 496         kill_litter_super(sb);
 497         pstore_sb = NULL;
 498 }
 499
 500 static struct file_system_type pstore_fs_type = {
 501         .owner          = THIS_MODULE,
 502         .name           = "pstore",
 503         .mount          = pstore_mount,
 504         .kill_sb        = pstore_kill_sb,
 505 };
 506
 507 static int __init init_pstore_fs(void)
 508 {
 509         int err;
 510
 511         /* Create a convenient mount point for people to access pstore */
 512         err = sysfs_create_mount_point(fs_kobj, "pstore");
 513         if (err)
 514                 goto out;
 515
 516         err = register_filesystem(&pstore_fs_type);
 517         if (err < 0)
 518                 sysfs_remove_mount_point(fs_kobj, "pstore");
 519
 520 out:
 521         return err;
 522 }
 523 module_init(init_pstore_fs)
 524
 525 static void __exit exit_pstore_fs(void)
 526 {
 527         unregister_filesystem(&pstore_fs_type);
 528         sysfs_remove_mount_point(fs_kobj, "pstore");
 529 }
 530 module_exit(exit_pstore_fs)
 531
 532 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 533 MODULE_LICENSE("GPL");