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_info *psi;
  50         enum pstore_type_id type;
  51         u64     id;
  52         ssize_t size;
  53         char    data[];
  54 };
  55
  56 struct 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
  64 static 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
  84 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
  85 {
  86         kfree(v);
  87 }
  88
  89 static 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
 102 static 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
 115 static 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
 122 static 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
 133 static 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
 153 static 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
 162 static 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  */
 173 static 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
 183 static 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
 197 static const struct inode_operations pstore_dir_inode_operations = {
 198         .lookup         = simple_lookup,
 199         .unlink         = pstore_unlink,
 200 };
 201
 202 static 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
 212 enum {
 213         Opt_kmsg_bytes, Opt_err
 214 };
 215
 216 static const match_table_t tokens = {
 217         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
 218         {Opt_err, NULL}
 219 };
 220
 221 static 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
 246 static int pstore_remount(struct super_block *sb, int *flags, char *data)
 247 {
 248         parse_options(data);
 249
 250         return 0;
 251 }
 252
 253 static 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
 261 static struct super_block *pstore_sb;
 262
 263 int 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  */
 273 int 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
 357 fail_lockedalloc:
 358         mutex_unlock(&root->d_inode->i_mutex);
 359         kfree(private);
 360 fail_alloc:
 361         iput(inode);
 362
 363 fail:
 364         return rc;
 365 }
 366
 367 static 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
 400 static 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
 406 static void pstore_kill_sb(struct super_block *sb)
 407 {
 408         kill_litter_super(sb);
 409         pstore_sb = NULL;
 410 }
 411
 412 static struct file_system_type pstore_fs_type = {
 413         .name           = "pstore",
 414         .mount          = pstore_mount,
 415         .kill_sb        = pstore_kill_sb,
 416 };
 417
 418 static int __init init_pstore_fs(void)
 419 {
 420         return register_filesystem(&pstore_fs_type);
 421 }
 422 module_init(init_pstore_fs)
 423
 424 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
 425 MODULE_LICENSE("GPL");