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 = d_inode(dentry)->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                               d_inode(dentry)->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 bool 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_PPC_OPAL:
 368                 sprintf(name, "powerpc-opal-%s-%lld", psname, id);
 369                 break;
 370         case PSTORE_TYPE_UNKNOWN:
 371                 scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
 372                 break;
 373         default:
 374                 scnprintf(name, sizeof(name), "type%d-%s-%lld",
 375                           type, psname, id);
 376                 break;
 377         }
 378
 379         mutex_lock(&d_inode(root)->i_mutex);
 380
 381         dentry = d_alloc_name(root, name);
 382         if (!dentry)
 383                 goto fail_lockedalloc;
 384
 385         memcpy(private->data, data, size);
 386         inode->i_size = private->size = size;
 387
 388         inode->i_private = private;
 389
 390         if (time.tv_sec)
 391                 inode->i_mtime = inode->i_ctime = time;
 392
 393         d_add(dentry, inode);
 394
 395         spin_lock_irqsave(&allpstore_lock, flags);
 396         list_add(&private->list, &allpstore);
 397         spin_unlock_irqrestore(&allpstore_lock, flags);
 398
 399         mutex_unlock(&d_inode(root)->i_mutex);
 400
 401         return 0;
 402
 403 fail_lockedalloc:
 404         mutex_unlock(&d_inode(root)->i_mutex);
 405         kfree(private);
 406 fail_alloc:
 407         iput(inode);
 408
 409 fail:
 410         return rc;
 411 }
 412
 413 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 414 {
 415         struct inode *inode;
 416
 417         save_mount_options(sb, data);
 418
 419         pstore_sb = sb;
 420
 421         sb->s_maxbytes          = MAX_LFS_FILESIZE;
 422         sb->s_blocksize         = PAGE_CACHE_SIZE;
 423         sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 424         sb->s_magic             = PSTOREFS_MAGIC;
 425         sb->s_op                = &pstore_ops;
 426         sb->s_time_gran         = 1;
 427
 428         parse_options(data);
 429
 430         inode = pstore_get_inode(sb);
 431         if (inode) {
 432                 inode->i_mode = S_IFDIR | 0755;
 433                 inode->i_op = &pstore_dir_inode_operations;
 434                 inode->i_fop = &simple_dir_operations;
 435                 inc_nlink(inode);
 436         }
 437         sb->s_root = d_make_root(inode);
 438         if (!sb->s_root)
 439                 return -ENOMEM;
 440
 441         pstore_get_records(0);
 442
 443         return 0;
 444 }
 445
 446 static struct dentry *pstore_mount(struct file_system_type *fs_type,
 447         int flags, const char *dev_name, void *data)
 448 {
 449         return mount_single(fs_type, flags, data, pstore_fill_super);
 450 }
 451
 452 static void pstore_kill_sb(struct super_block *sb)
 453 {
 454         kill_litter_super(sb);
 455         pstore_sb = NULL;
 456 }
 457
 458 static struct file_system_type pstore_fs_type = {
 459         .owner          = THIS_MODULE,
 460         .name           = "pstore",
 461         .mount          = pstore_mount,
 462         .kill_sb        = pstore_kill_sb,
 463 };
 464
 465 static int __init init_pstore_fs(void)
 466 {
 467         int err;
 468
 469         /* Create a convenient mount point for people to access pstore */
 470         err = sysfs_create_mount_point(fs_kobj, "pstore");
 471         if (err)
 472                 goto out;
 473
 474         err = register_filesystem(&pstore_fs_type);
 475         if (err < 0)
 476                 sysfs_remove_mount_point(fs_kobj, "pstore");
 477
 478 out:
 479         return err;
 480 }
 481 module_init(init_pstore_fs)
 482
 483 static void __exit exit_pstore_fs(void)
 484 {
 485         unregister_filesystem(&pstore_fs_type);
 486         sysfs_remove_mount_point(fs_kobj, "pstore");
 487 }
 488 module_exit(exit_pstore_fs)
 489
 490 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 491 MODULE_LICENSE("GPL");