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