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
  40#include "internal.h"
  41
  42#define PSTORE_NAMELEN  64
  43
  44static DEFINE_SPINLOCK(allpstore_lock);
  45static LIST_HEAD(allpstore);
  46
  47struct pstore_private {
  48        struct list_head list;
  49        struct pstore_info *psi;
  50        enum pstore_type_id type;
  51        u64     id;
  52        ssize_t size;
  53        char    data[];
  54};
  55
  56struct pstore_ftrace_seq_data {
  57        const void *ptr;
  58        size_t off;
  59        size_t size;
  60};
  61
  62#define REC_SIZE sizeof(struct pstore_ftrace_record)
  63
  64static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
  65{
  66        struct pstore_private *ps = s->private;
  67        struct pstore_ftrace_seq_data *data;
  68
  69        data = kzalloc(sizeof(*data), GFP_KERNEL);
  70        if (!data)
  71                return NULL;
  72
  73        data->off = ps->size % REC_SIZE;
  74        data->off += *pos * REC_SIZE;
  75        if (data->off + REC_SIZE > ps->size) {
  76                kfree(data);
  77                return NULL;
  78        }
  79
  80        return data;
  81
  82}
  83
  84static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
  85{
  86        kfree(v);
  87}
  88
  89static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
  90{
  91        struct pstore_private *ps = s->private;
  92        struct pstore_ftrace_seq_data *data = v;
  93
  94        data->off += REC_SIZE;
  95        if (data->off + REC_SIZE > ps->size)
  96                return NULL;
  97
  98        (*pos)++;
  99        return data;
 100}
 101
 102static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
 103{
 104        struct pstore_private *ps = s->private;
 105        struct pstore_ftrace_seq_data *data = v;
 106        struct pstore_ftrace_record *rec = (void *)(ps->data + data->off);
 107
 108        seq_printf(s, "%d %08lx  %08lx  %pf <- %pF\n",
 109                pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
 110                (void *)rec->ip, (void *)rec->parent_ip);
 111
 112        return 0;
 113}
 114
 115static const struct seq_operations pstore_ftrace_seq_ops = {
 116        .start  = pstore_ftrace_seq_start,
 117        .next   = pstore_ftrace_seq_next,
 118        .stop   = pstore_ftrace_seq_stop,
 119        .show   = pstore_ftrace_seq_show,
 120};
 121
 122static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
 123                                                size_t count, loff_t *ppos)
 124{
 125        struct seq_file *sf = file->private_data;
 126        struct pstore_private *ps = sf->private;
 127
 128        if (ps->type == PSTORE_TYPE_FTRACE)
 129                return seq_read(file, userbuf, count, ppos);
 130        return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
 131}
 132
 133static int pstore_file_open(struct inode *inode, struct file *file)
 134{
 135        struct pstore_private *ps = inode->i_private;
 136        struct seq_file *sf;
 137        int err;
 138        const struct seq_operations *sops = NULL;
 139
 140        if (ps->type == PSTORE_TYPE_FTRACE)
 141                sops = &pstore_ftrace_seq_ops;
 142
 143        err = seq_open(file, sops);
 144        if (err < 0)
 145                return err;
 146
 147        sf = file->private_data;
 148        sf->private = ps;
 149
 150        return 0;
 151}
 152
 153static loff_t pstore_file_llseek(struct file *file, loff_t off, int origin)
 154{
 155        struct seq_file *sf = file->private_data;
 156
 157        if (sf->op)
 158                return seq_lseek(file, off, origin);
 159        return default_llseek(file, off, origin);
 160}
 161
 162static const struct file_operations pstore_file_operations = {
 163        .open           = pstore_file_open,
 164        .read           = pstore_file_read,
 165        .llseek         = pstore_file_llseek,
 166        .release        = seq_release,
 167};
 168
 169/*
 170 * When a file is unlinked from our file system we call the
 171 * platform driver to erase the record from persistent store.
 172 */
 173static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 174{
 175        struct pstore_private *p = dentry->d_inode->i_private;
 176
 177        if (p->psi->erase)
 178                p->psi->erase(p->type, p->id, p->psi);
 179
 180        return simple_unlink(dir, dentry);
 181}
 182
 183static void pstore_evict_inode(struct inode *inode)
 184{
 185        struct pstore_private   *p = inode->i_private;
 186        unsigned long           flags;
 187
 188        clear_inode(inode);
 189        if (p) {
 190                spin_lock_irqsave(&allpstore_lock, flags);
 191                list_del(&p->list);
 192                spin_unlock_irqrestore(&allpstore_lock, flags);
 193                kfree(p);
 194        }
 195}
 196
 197static const struct inode_operations pstore_dir_inode_operations = {
 198        .lookup         = simple_lookup,
 199        .unlink         = pstore_unlink,
 200};
 201
 202static struct inode *pstore_get_inode(struct super_block *sb)
 203{
 204        struct inode *inode = new_inode(sb);
 205        if (inode) {
 206                inode->i_ino = get_next_ino();
 207                inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 208        }
 209        return inode;
 210}
 211
 212enum {
 213        Opt_kmsg_bytes, Opt_err
 214};
 215
 216static const match_table_t tokens = {
 217        {Opt_kmsg_bytes, "kmsg_bytes=%u"},
 218        {Opt_err, NULL}
 219};
 220
 221static void parse_options(char *options)
 222{
 223        char            *p;
 224        substring_t     args[MAX_OPT_ARGS];
 225        int             option;
 226
 227        if (!options)
 228                return;
 229
 230        while ((p = strsep(&options, ",")) != NULL) {
 231                int token;
 232
 233                if (!*p)
 234                        continue;
 235
 236                token = match_token(p, tokens, args);
 237                switch (token) {
 238                case Opt_kmsg_bytes:
 239                        if (!match_int(&args[0], &option))
 240                                pstore_set_kmsg_bytes(option);
 241                        break;
 242                }
 243        }
 244}
 245
 246static int pstore_remount(struct super_block *sb, int *flags, char *data)
 247{
 248        parse_options(data);
 249
 250        return 0;
 251}
 252
 253static const struct super_operations pstore_ops = {
 254        .statfs         = simple_statfs,
 255        .drop_inode     = generic_delete_inode,
 256        .evict_inode    = pstore_evict_inode,
 257        .remount_fs     = pstore_remount,
 258        .show_options   = generic_show_options,
 259};
 260
 261static struct super_block *pstore_sb;
 262
 263int pstore_is_mounted(void)
 264{
 265        return pstore_sb != NULL;
 266}
 267
 268/*
 269 * Make a regular file in the root directory of our file system.
 270 * Load it up with "size" bytes of data from "buf".
 271 * Set the mtime & ctime to the date that this record was originally stored.
 272 */
 273int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
 274                  char *data, size_t size, struct timespec time,
 275                  struct pstore_info *psi)
 276{
 277        struct dentry           *root = pstore_sb->s_root;
 278        struct dentry           *dentry;
 279        struct inode            *inode;
 280        int                     rc = 0;
 281        char                    name[PSTORE_NAMELEN];
 282        struct pstore_private   *private, *pos;
 283        unsigned long           flags;
 284
 285        spin_lock_irqsave(&allpstore_lock, flags);
 286        list_for_each_entry(pos, &allpstore, list) {
 287                if (pos->type == type &&
 288                    pos->id == id &&
 289                    pos->psi == psi) {
 290                        rc = -EEXIST;
 291                        break;
 292                }
 293        }
 294        spin_unlock_irqrestore(&allpstore_lock, flags);
 295        if (rc)
 296                return rc;
 297
 298        rc = -ENOMEM;
 299        inode = pstore_get_inode(pstore_sb);
 300        if (!inode)
 301                goto fail;
 302        inode->i_mode = S_IFREG | 0444;
 303        inode->i_fop = &pstore_file_operations;
 304        private = kmalloc(sizeof *private + size, GFP_KERNEL);
 305        if (!private)
 306                goto fail_alloc;
 307        private->type = type;
 308        private->id = id;
 309        private->psi = psi;
 310
 311        switch (type) {
 312        case PSTORE_TYPE_DMESG:
 313                sprintf(name, "dmesg-%s-%lld", psname, id);
 314                break;
 315        case PSTORE_TYPE_CONSOLE:
 316                sprintf(name, "console-%s", psname);
 317                break;
 318        case PSTORE_TYPE_FTRACE:
 319                sprintf(name, "ftrace-%s", psname);
 320                break;
 321        case PSTORE_TYPE_MCE:
 322                sprintf(name, "mce-%s-%lld", psname, id);
 323                break;
 324        case PSTORE_TYPE_UNKNOWN:
 325                sprintf(name, "unknown-%s-%lld", psname, id);
 326                break;
 327        default:
 328                sprintf(name, "type%d-%s-%lld", type, psname, id);
 329                break;
 330        }
 331
 332        mutex_lock(&root->d_inode->i_mutex);
 333
 334        rc = -ENOSPC;
 335        dentry = d_alloc_name(root, name);
 336        if (IS_ERR(dentry))
 337                goto fail_lockedalloc;
 338
 339        memcpy(private->data, data, size);
 340        inode->i_size = private->size = size;
 341
 342        inode->i_private = private;
 343
 344        if (time.tv_sec)
 345                inode->i_mtime = inode->i_ctime = time;
 346
 347        d_add(dentry, inode);
 348
 349        spin_lock_irqsave(&allpstore_lock, flags);
 350        list_add(&private->list, &allpstore);
 351        spin_unlock_irqrestore(&allpstore_lock, flags);
 352
 353        mutex_unlock(&root->d_inode->i_mutex);
 354
 355        return 0;
 356
 357fail_lockedalloc:
 358        mutex_unlock(&root->d_inode->i_mutex);
 359        kfree(private);
 360fail_alloc:
 361        iput(inode);
 362
 363fail:
 364        return rc;
 365}
 366
 367static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 368{
 369        struct inode *inode;
 370
 371        save_mount_options(sb, data);
 372
 373        pstore_sb = sb;
 374
 375        sb->s_maxbytes          = MAX_LFS_FILESIZE;
 376        sb->s_blocksize         = PAGE_CACHE_SIZE;
 377        sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 378        sb->s_magic             = PSTOREFS_MAGIC;
 379        sb->s_op                = &pstore_ops;
 380        sb->s_time_gran         = 1;
 381
 382        parse_options(data);
 383
 384        inode = pstore_get_inode(sb);
 385        if (inode) {
 386                inode->i_mode = S_IFDIR | 0755;
 387                inode->i_op = &pstore_dir_inode_operations;
 388                inode->i_fop = &simple_dir_operations;
 389                inc_nlink(inode);
 390        }
 391        sb->s_root = d_make_root(inode);
 392        if (!sb->s_root)
 393                return -ENOMEM;
 394
 395        pstore_get_records(0);
 396
 397        return 0;
 398}
 399
 400static struct dentry *pstore_mount(struct file_system_type *fs_type,
 401        int flags, const char *dev_name, void *data)
 402{
 403        return mount_single(fs_type, flags, data, pstore_fill_super);
 404}
 405
 406static void pstore_kill_sb(struct super_block *sb)
 407{
 408        kill_litter_super(sb);
 409        pstore_sb = NULL;
 410}
 411
 412static struct file_system_type pstore_fs_type = {
 413        .name           = "pstore",
 414        .mount          = pstore_mount,
 415        .kill_sb        = pstore_kill_sb,
 416};
 417
 418static int __init init_pstore_fs(void)
 419{
 420        return register_filesystem(&pstore_fs_type);
 421}
 422module_init(init_pstore_fs)
 423
 424MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 425MODULE_LICENSE("GPL");
 426
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