linux/fs/pstore/inode.c
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   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
  45static DEFINE_SPINLOCK(allpstore_lock);
  46static LIST_HEAD(allpstore);
  47
  48struct 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
  58struct 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
  66static 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
  86static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
  87{
  88        kfree(v);
  89}
  90
  91static 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
 104static 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
 117static 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
 124static 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
 136static 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
 147static 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
 171static 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
 180static 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 */
 191static 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
 209static 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
 223static const struct inode_operations pstore_dir_inode_operations = {
 224        .lookup         = simple_lookup,
 225        .unlink         = pstore_unlink,
 226};
 227
 228static 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
 238enum {
 239        Opt_kmsg_bytes, Opt_err
 240};
 241
 242static const match_table_t tokens = {
 243        {Opt_kmsg_bytes, "kmsg_bytes=%u"},
 244        {Opt_err, NULL}
 245};
 246
 247static 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
 272static 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
 280static 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
 288static struct super_block *pstore_sb;
 289
 290int 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 */
 300int 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
 403fail_lockedalloc:
 404        mutex_unlock(&d_inode(root)->i_mutex);
 405        kfree(private);
 406fail_alloc:
 407        iput(inode);
 408
 409fail:
 410        return rc;
 411}
 412
 413static 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
 446static 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
 452static void pstore_kill_sb(struct super_block *sb)
 453{
 454        kill_litter_super(sb);
 455        pstore_sb = NULL;
 456}
 457
 458static struct file_system_type pstore_fs_type = {
 459        .name           = "pstore",
 460        .mount          = pstore_mount,
 461        .kill_sb        = pstore_kill_sb,
 462};
 463
 464static int __init init_pstore_fs(void)
 465{
 466        int err;
 467
 468        /* Create a convenient mount point for people to access pstore */
 469        err = sysfs_create_mount_point(fs_kobj, "pstore");
 470        if (err)
 471                goto out;
 472
 473        err = register_filesystem(&pstore_fs_type);
 474        if (err < 0)
 475                sysfs_remove_mount_point(fs_kobj, "pstore");
 476
 477out:
 478        return err;
 479}
 480module_init(init_pstore_fs)
 481
 482MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 483MODULE_LICENSE("GPL");
 484