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, "CPU:%d ts:%llu %08lx  %08lx  %pf <- %pF\n",
 111                    pstore_ftrace_decode_cpu(rec),
 112                    pstore_ftrace_read_timestamp(rec),
 113                    rec->ip, rec->parent_ip, (void *)rec->ip,
 114                    (void *)rec->parent_ip);
 115
 116         return 0;
 117 }
 118
 119 static const struct seq_operations pstore_ftrace_seq_ops = {
 120         .start  = pstore_ftrace_seq_start,
 121         .next   = pstore_ftrace_seq_next,
 122         .stop   = pstore_ftrace_seq_stop,
 123         .show   = pstore_ftrace_seq_show,
 124 };
 125
 126 static int pstore_check_syslog_permissions(struct pstore_private *ps)
 127 {
 128         switch (ps->type) {
 129         case PSTORE_TYPE_DMESG:
 130         case PSTORE_TYPE_CONSOLE:
 131                 return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
 132                         SYSLOG_FROM_READER);
 133         default:
 134                 return 0;
 135         }
 136 }
 137
 138 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
 139                                                 size_t count, loff_t *ppos)
 140 {
 141         struct seq_file *sf = file->private_data;
 142         struct pstore_private *ps = sf->private;
 143
 144         if (ps->type == PSTORE_TYPE_FTRACE)
 145                 return seq_read(file, userbuf, count, ppos);
 146         return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->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         err = pstore_check_syslog_permissions(ps);
 157         if (err)
 158                 return err;
 159
 160         if (ps->type == PSTORE_TYPE_FTRACE)
 161                 sops = &pstore_ftrace_seq_ops;
 162
 163         err = seq_open(file, sops);
 164         if (err < 0)
 165                 return err;
 166
 167         sf = file->private_data;
 168         sf->private = ps;
 169
 170         return 0;
 171 }
 172
 173 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
 174 {
 175         struct seq_file *sf = file->private_data;
 176
 177         if (sf->op)
 178                 return seq_lseek(file, off, whence);
 179         return default_llseek(file, off, whence);
 180 }
 181
 182 static const struct file_operations pstore_file_operations = {
 183         .open           = pstore_file_open,
 184         .read           = pstore_file_read,
 185         .llseek         = pstore_file_llseek,
 186         .release        = seq_release,
 187 };
 188
 189 /*
 190  * When a file is unlinked from our file system we call the
 191  * platform driver to erase the record from persistent store.
 192  */
 193 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 194 {
 195         struct pstore_private *p = d_inode(dentry)->i_private;
 196         int err;
 197
 198         err = pstore_check_syslog_permissions(p);
 199         if (err)
 200                 return err;
 201
 202         if (p->psi->erase) {
 203                 mutex_lock(&p->psi->read_mutex);
 204                 p->psi->erase(p->type, p->id, p->count,
 205                               d_inode(dentry)->i_ctime, p->psi);
 206                 mutex_unlock(&p->psi->read_mutex);
 207         } else {
 208                 return -EPERM;
 209         }
 210
 211         return simple_unlink(dir, dentry);
 212 }
 213
 214 static void pstore_evict_inode(struct inode *inode)
 215 {
 216         struct pstore_private   *p = inode->i_private;
 217         unsigned long           flags;
 218
 219         clear_inode(inode);
 220         if (p) {
 221                 spin_lock_irqsave(&allpstore_lock, flags);
 222                 list_del(&p->list);
 223                 spin_unlock_irqrestore(&allpstore_lock, flags);
 224                 kfree(p);
 225         }
 226 }
 227
 228 static const struct inode_operations pstore_dir_inode_operations = {
 229         .lookup         = simple_lookup,
 230         .unlink         = pstore_unlink,
 231 };
 232
 233 static struct inode *pstore_get_inode(struct super_block *sb)
 234 {
 235         struct inode *inode = new_inode(sb);
 236         if (inode) {
 237                 inode->i_ino = get_next_ino();
 238                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 239         }
 240         return inode;
 241 }
 242
 243 enum {
 244         Opt_kmsg_bytes, Opt_err
 245 };
 246
 247 static const match_table_t tokens = {
 248         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
 249         {Opt_err, NULL}
 250 };
 251
 252 static void parse_options(char *options)
 253 {
 254         char            *p;
 255         substring_t     args[MAX_OPT_ARGS];
 256         int             option;
 257
 258         if (!options)
 259                 return;
 260
 261         while ((p = strsep(&options, ",")) != NULL) {
 262                 int token;
 263
 264                 if (!*p)
 265                         continue;
 266
 267                 token = match_token(p, tokens, args);
 268                 switch (token) {
 269                 case Opt_kmsg_bytes:
 270                         if (!match_int(&args[0], &option))
 271                                 pstore_set_kmsg_bytes(option);
 272                         break;
 273                 }
 274         }
 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   = generic_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(enum pstore_type_id type, char *psname, u64 id, int count,
 306                   char *data, bool compressed, size_t size,
 307                   struct timespec time, struct pstore_info *psi)
 308 {
 309         struct dentry           *root = pstore_sb->s_root;
 310         struct dentry           *dentry;
 311         struct inode            *inode;
 312         int                     rc = 0;
 313         char                    name[PSTORE_NAMELEN];
 314         struct pstore_private   *private, *pos;
 315         unsigned long           flags;
 316
 317         spin_lock_irqsave(&allpstore_lock, flags);
 318         list_for_each_entry(pos, &allpstore, list) {
 319                 if (pos->type == type &&
 320                     pos->id == id &&
 321                     pos->psi == 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(pstore_sb);
 332         if (!inode)
 333                 goto fail;
 334         inode->i_mode = S_IFREG | 0444;
 335         inode->i_fop = &pstore_file_operations;
 336         private = kmalloc(sizeof *private + size, GFP_KERNEL);
 337         if (!private)
 338                 goto fail_alloc;
 339         private->type = type;
 340         private->id = id;
 341         private->count = count;
 342         private->psi = psi;
 343
 344         switch (type) {
 345         case PSTORE_TYPE_DMESG:
 346                 scnprintf(name, sizeof(name), "dmesg-%s-%lld%s",
 347                           psname, id, compressed ? ".enc.z" : "");
 348                 break;
 349         case PSTORE_TYPE_CONSOLE:
 350                 scnprintf(name, sizeof(name), "console-%s-%lld", psname, id);
 351                 break;
 352         case PSTORE_TYPE_FTRACE:
 353                 scnprintf(name, sizeof(name), "ftrace-%s-%lld", psname, id);
 354                 break;
 355         case PSTORE_TYPE_MCE:
 356                 scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
 357                 break;
 358         case PSTORE_TYPE_PPC_RTAS:
 359                 scnprintf(name, sizeof(name), "rtas-%s-%lld", psname, id);
 360                 break;
 361         case PSTORE_TYPE_PPC_OF:
 362                 scnprintf(name, sizeof(name), "powerpc-ofw-%s-%lld",
 363                           psname, id);
 364                 break;
 365         case PSTORE_TYPE_PPC_COMMON:
 366                 scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
 367                           psname, id);
 368                 break;
 369         case PSTORE_TYPE_PMSG:
 370                 scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
 371                 break;
 372         case PSTORE_TYPE_PPC_OPAL:
 373                 sprintf(name, "powerpc-opal-%s-%lld", psname, id);
 374                 break;
 375         case PSTORE_TYPE_UNKNOWN:
 376                 scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
 377                 break;
 378         default:
 379                 scnprintf(name, sizeof(name), "type%d-%s-%lld",
 380                           type, psname, id);
 381                 break;
 382         }
 383
 384         inode_lock(d_inode(root));
 385
 386         dentry = d_alloc_name(root, name);
 387         if (!dentry)
 388                 goto fail_lockedalloc;
 389
 390         memcpy(private->data, data, size);
 391         inode->i_size = private->size = size;
 392
 393         inode->i_private = private;
 394
 395         if (time.tv_sec)
 396                 inode->i_mtime = inode->i_ctime = time;
 397
 398         d_add(dentry, inode);
 399
 400         spin_lock_irqsave(&allpstore_lock, flags);
 401         list_add(&private->list, &allpstore);
 402         spin_unlock_irqrestore(&allpstore_lock, flags);
 403
 404         inode_unlock(d_inode(root));
 405
 406         return 0;
 407
 408 fail_lockedalloc:
 409         inode_unlock(d_inode(root));
 410         kfree(private);
 411 fail_alloc:
 412         iput(inode);
 413
 414 fail:
 415         return rc;
 416 }
 417
 418 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 419 {
 420         struct inode *inode;
 421
 422         save_mount_options(sb, data);
 423
 424         pstore_sb = sb;
 425
 426         sb->s_maxbytes          = MAX_LFS_FILESIZE;
 427         sb->s_blocksize         = PAGE_SIZE;
 428         sb->s_blocksize_bits    = PAGE_SHIFT;
 429         sb->s_magic             = PSTOREFS_MAGIC;
 430         sb->s_op                = &pstore_ops;
 431         sb->s_time_gran         = 1;
 432
 433         parse_options(data);
 434
 435         inode = pstore_get_inode(sb);
 436         if (inode) {
 437                 inode->i_mode = S_IFDIR | 0755;
 438                 inode->i_op = &pstore_dir_inode_operations;
 439                 inode->i_fop = &simple_dir_operations;
 440                 inc_nlink(inode);
 441         }
 442         sb->s_root = d_make_root(inode);
 443         if (!sb->s_root)
 444                 return -ENOMEM;
 445
 446         pstore_get_records(0);
 447
 448         return 0;
 449 }
 450
 451 static struct dentry *pstore_mount(struct file_system_type *fs_type,
 452         int flags, const char *dev_name, void *data)
 453 {
 454         return mount_single(fs_type, flags, data, pstore_fill_super);
 455 }
 456
 457 static void pstore_kill_sb(struct super_block *sb)
 458 {
 459         kill_litter_super(sb);
 460         pstore_sb = NULL;
 461 }
 462
 463 static struct file_system_type pstore_fs_type = {
 464         .owner          = THIS_MODULE,
 465         .name           = "pstore",
 466         .mount          = pstore_mount,
 467         .kill_sb        = pstore_kill_sb,
 468 };
 469
 470 static int __init init_pstore_fs(void)
 471 {
 472         int err;
 473
 474         /* Create a convenient mount point for people to access pstore */
 475         err = sysfs_create_mount_point(fs_kobj, "pstore");
 476         if (err)
 477                 goto out;
 478
 479         err = register_filesystem(&pstore_fs_type);
 480         if (err < 0)
 481                 sysfs_remove_mount_point(fs_kobj, "pstore");
 482
 483 out:
 484         return err;
 485 }
 486 module_init(init_pstore_fs)
 487
 488 static void __exit exit_pstore_fs(void)
 489 {
 490         unregister_filesystem(&pstore_fs_type);
 491         sysfs_remove_mount_point(fs_kobj, "pstore");
 492 }
 493 module_exit(exit_pstore_fs)
 494
 495 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 496 MODULE_LICENSE("GPL");