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 }