fs/pstore/inode.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Persistent Storage - ramfs parts.
   4  *
   5  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/fs.h>
  10 #include <linux/fsnotify.h>
  11 #include <linux/pagemap.h>
  12 #include <linux/highmem.h>
  13 #include <linux/time.h>
  14 #include <linux/init.h>
  15 #include <linux/list.h>
  16 #include <linux/string.h>
  17 #include <linux/mount.h>
  18 #include <linux/seq_file.h>
  19 #include <linux/ramfs.h>
  20 #include <linux/parser.h>
  21 #include <linux/sched.h>
  22 #include <linux/magic.h>
  23 #include <linux/pstore.h>
  24 #include <linux/slab.h>
  25 #include <linux/uaccess.h>
  26
  27 #include "internal.h"
  28
  29 #define PSTORE_NAMELEN  64
  30
  31 static DEFINE_MUTEX(records_list_lock);
  32 static LIST_HEAD(records_list);
  33
  34 static DEFINE_MUTEX(pstore_sb_lock);
  35 static struct super_block *pstore_sb;
  36
  37 struct pstore_private {
  38         struct list_head list;
  39         struct dentry *dentry;
  40         struct pstore_record *record;
  41         size_t total_size;
  42 };
  43
  44 struct pstore_ftrace_seq_data {
  45         const void *ptr;
  46         size_t off;
  47         size_t size;
  48 };
  49
  50 #define REC_SIZE sizeof(struct pstore_ftrace_record)
  51
  52 static void free_pstore_private(struct pstore_private *private)
  53 {
  54         if (!private)
  55                 return;
  56         if (private->record) {
  57                 kfree(private->record->buf);
  58                 kfree(private->record);
  59         }
  60         kfree(private);
  61 }
  62
  63 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
  64 {
  65         struct pstore_private *ps = s->private;
  66         struct pstore_ftrace_seq_data *data;
  67
  68         data = kzalloc(sizeof(*data), GFP_KERNEL);
  69         if (!data)
  70                 return NULL;
  71
  72         data->off = ps->total_size % REC_SIZE;
  73         data->off += *pos * REC_SIZE;
  74         if (data->off + REC_SIZE > ps->total_size) {
  75                 kfree(data);
  76                 return NULL;
  77         }
  78
  79         return data;
  80
  81 }
  82
  83 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
  84 {
  85         kfree(v);
  86 }
  87
  88 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
  89 {
  90         struct pstore_private *ps = s->private;
  91         struct pstore_ftrace_seq_data *data = v;
  92
  93         (*pos)++;
  94         data->off += REC_SIZE;
  95         if (data->off + REC_SIZE > ps->total_size)
  96                 return NULL;
  97
  98         return data;
  99 }
 100
 101 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
 102 {
 103         struct pstore_private *ps = s->private;
 104         struct pstore_ftrace_seq_data *data = v;
 105         struct pstore_ftrace_record *rec;
 106
 107         if (!data)
 108                 return 0;
 109
 110         rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
 111
 112         seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
 113                    pstore_ftrace_decode_cpu(rec),
 114                    pstore_ftrace_read_timestamp(rec),
 115                    rec->ip, rec->parent_ip, (void *)rec->ip,
 116                    (void *)rec->parent_ip);
 117
 118         return 0;
 119 }
 120
 121 static const struct seq_operations pstore_ftrace_seq_ops = {
 122         .start  = pstore_ftrace_seq_start,
 123         .next   = pstore_ftrace_seq_next,
 124         .stop   = pstore_ftrace_seq_stop,
 125         .show   = pstore_ftrace_seq_show,
 126 };
 127
 128 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
 129                                                 size_t count, loff_t *ppos)
 130 {
 131         struct seq_file *sf = file->private_data;
 132         struct pstore_private *ps = sf->private;
 133
 134         if (ps->record->type == PSTORE_TYPE_FTRACE)
 135                 return seq_read(file, userbuf, count, ppos);
 136         return simple_read_from_buffer(userbuf, count, ppos,
 137                                        ps->record->buf, ps->total_size);
 138 }
 139
 140 static int pstore_file_open(struct inode *inode, struct file *file)
 141 {
 142         struct pstore_private *ps = inode->i_private;
 143         struct seq_file *sf;
 144         int err;
 145         const struct seq_operations *sops = NULL;
 146
 147         if (ps->record->type == PSTORE_TYPE_FTRACE)
 148                 sops = &pstore_ftrace_seq_ops;
 149
 150         err = seq_open(file, sops);
 151         if (err < 0)
 152                 return err;
 153
 154         sf = file->private_data;
 155         sf->private = ps;
 156
 157         return 0;
 158 }
 159
 160 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
 161 {
 162         struct seq_file *sf = file->private_data;
 163
 164         if (sf->op)
 165                 return seq_lseek(file, off, whence);
 166         return default_llseek(file, off, whence);
 167 }
 168
 169 static const struct file_operations pstore_file_operations = {
 170         .open           = pstore_file_open,
 171         .read           = pstore_file_read,
 172         .llseek         = pstore_file_llseek,
 173         .release        = seq_release,
 174 };
 175
 176 /*
 177  * When a file is unlinked from our file system we call the
 178  * platform driver to erase the record from persistent store.
 179  */
 180 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 181 {
 182         struct pstore_private *p = d_inode(dentry)->i_private;
 183         struct pstore_record *record = p->record;
 184         int rc = 0;
 185
 186         if (!record->psi->erase)
 187                 return -EPERM;
 188
 189         /* Make sure we can't race while removing this file. */
 190         mutex_lock(&records_list_lock);
 191         if (!list_empty(&p->list))
 192                 list_del_init(&p->list);
 193         else
 194                 rc = -ENOENT;
 195         p->dentry = NULL;
 196         mutex_unlock(&records_list_lock);
 197         if (rc)
 198                 return rc;
 199
 200         mutex_lock(&record->psi->read_mutex);
 201         record->psi->erase(record);
 202         mutex_unlock(&record->psi->read_mutex);
 203
 204         return simple_unlink(dir, dentry);
 205 }
 206
 207 static void pstore_evict_inode(struct inode *inode)
 208 {
 209         struct pstore_private   *p = inode->i_private;
 210
 211         clear_inode(inode);
 212         free_pstore_private(p);
 213 }
 214
 215 static const struct inode_operations pstore_dir_inode_operations = {
 216         .lookup         = simple_lookup,
 217         .unlink         = pstore_unlink,
 218 };
 219
 220 static struct inode *pstore_get_inode(struct super_block *sb)
 221 {
 222         struct inode *inode = new_inode(sb);
 223         if (inode) {
 224                 inode->i_ino = get_next_ino();
 225                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 226         }
 227         return inode;
 228 }
 229
 230 enum {
 231         Opt_kmsg_bytes, Opt_err
 232 };
 233
 234 static const match_table_t tokens = {
 235         {Opt_kmsg_bytes, "kmsg_bytes=%u"},
 236         {Opt_err, NULL}
 237 };
 238
 239 static void parse_options(char *options)
 240 {
 241         char            *p;
 242         substring_t     args[MAX_OPT_ARGS];
 243         int             option;
 244
 245         if (!options)
 246                 return;
 247
 248         while ((p = strsep(&options, ",")) != NULL) {
 249                 int token;
 250
 251                 if (!*p)
 252                         continue;
 253
 254                 token = match_token(p, tokens, args);
 255                 switch (token) {
 256                 case Opt_kmsg_bytes:
 257                         if (!match_int(&args[0], &option))
 258                                 pstore_set_kmsg_bytes(option);
 259                         break;
 260                 }
 261         }
 262 }
 263
 264 /*
 265  * Display the mount options in /proc/mounts.
 266  */
 267 static int pstore_show_options(struct seq_file *m, struct dentry *root)
 268 {
 269         if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
 270                 seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
 271         return 0;
 272 }
 273
 274 static int pstore_remount(struct super_block *sb, int *flags, char *data)
 275 {
 276         sync_filesystem(sb);
 277         parse_options(data);
 278
 279         return 0;
 280 }
 281
 282 static const struct super_operations pstore_ops = {
 283         .statfs         = simple_statfs,
 284         .drop_inode     = generic_delete_inode,
 285         .evict_inode    = pstore_evict_inode,
 286         .remount_fs     = pstore_remount,
 287         .show_options   = pstore_show_options,
 288 };
 289
 290 static struct dentry *psinfo_lock_root(void)
 291 {
 292         struct dentry *root;
 293
 294         mutex_lock(&pstore_sb_lock);
 295         /*
 296          * Having no backend is fine -- no records appear.
 297          * Not being mounted is fine -- nothing to do.
 298          */
 299         if (!psinfo || !pstore_sb) {
 300                 mutex_unlock(&pstore_sb_lock);
 301                 return NULL;
 302         }
 303
 304         root = pstore_sb->s_root;
 305         inode_lock(d_inode(root));
 306         mutex_unlock(&pstore_sb_lock);
 307
 308         return root;
 309 }
 310
 311 int pstore_put_backend_records(struct pstore_info *psi)
 312 {
 313         struct pstore_private *pos, *tmp;
 314         struct dentry *root;
 315         int rc = 0;
 316
 317         root = psinfo_lock_root();
 318         if (!root)
 319                 return 0;
 320
 321         mutex_lock(&records_list_lock);
 322         list_for_each_entry_safe(pos, tmp, &records_list, list) {
 323                 if (pos->record->psi == psi) {
 324                         list_del_init(&pos->list);
 325                         rc = simple_unlink(d_inode(root), pos->dentry);
 326                         if (WARN_ON(rc))
 327                                 break;
 328                         d_drop(pos->dentry);
 329                         dput(pos->dentry);
 330                         pos->dentry = NULL;
 331                 }
 332         }
 333         mutex_unlock(&records_list_lock);
 334
 335         inode_unlock(d_inode(root));
 336
 337         return rc;
 338 }
 339
 340 /*
 341  * Make a regular file in the root directory of our file system.
 342  * Load it up with "size" bytes of data from "buf".
 343  * Set the mtime & ctime to the date that this record was originally stored.
 344  */
 345 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 346 {
 347         struct dentry           *dentry;
 348         struct inode            *inode;
 349         int                     rc = 0;
 350         char                    name[PSTORE_NAMELEN];
 351         struct pstore_private   *private, *pos;
 352         size_t                  size = record->size + record->ecc_notice_size;
 353
 354         if (WARN_ON(!inode_is_locked(d_inode(root))))
 355                 return -EINVAL;
 356
 357         rc = -EEXIST;
 358         /* Skip records that are already present in the filesystem. */
 359         mutex_lock(&records_list_lock);
 360         list_for_each_entry(pos, &records_list, list) {
 361                 if (pos->record->type == record->type &&
 362                     pos->record->id == record->id &&
 363                     pos->record->psi == record->psi)
 364                         goto fail;
 365         }
 366
 367         rc = -ENOMEM;
 368         inode = pstore_get_inode(root->d_sb);
 369         if (!inode)
 370                 goto fail;
 371         inode->i_mode = S_IFREG | 0444;
 372         inode->i_fop = &pstore_file_operations;
 373         scnprintf(name, sizeof(name), "%s-%s-%llu%s",
 374                         pstore_type_to_name(record->type),
 375                         record->psi->name, record->id,
 376                         record->compressed ? ".enc.z" : "");
 377
 378         private = kzalloc(sizeof(*private), GFP_KERNEL);
 379         if (!private)
 380                 goto fail_inode;
 381
 382         dentry = d_alloc_name(root, name);
 383         if (!dentry)
 384                 goto fail_private;
 385
 386         private->dentry = dentry;
 387         private->record = record;
 388         inode->i_size = private->total_size = size;
 389         inode->i_private = private;
 390
 391         if (record->time.tv_sec)
 392                 inode->i_mtime = inode->i_ctime = record->time;
 393
 394         d_add(dentry, inode);
 395
 396         list_add(&private->list, &records_list);
 397         mutex_unlock(&records_list_lock);
 398
 399         return 0;
 400
 401 fail_private:
 402         free_pstore_private(private);
 403 fail_inode:
 404         iput(inode);
 405 fail:
 406         mutex_unlock(&records_list_lock);
 407         return rc;
 408 }
 409
 410 /*
 411  * Read all the records from the persistent store. Create
 412  * files in our filesystem.  Don't warn about -EEXIST errors
 413  * when we are re-scanning the backing store looking to add new
 414  * error records.
 415  */
 416 void pstore_get_records(int quiet)
 417 {
 418         struct dentry *root;
 419
 420         root = psinfo_lock_root();
 421         if (!root)
 422                 return;
 423
 424         pstore_get_backend_records(psinfo, root, quiet);
 425         inode_unlock(d_inode(root));
 426 }
 427
 428 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 429 {
 430         struct inode *inode;
 431
 432         sb->s_maxbytes          = MAX_LFS_FILESIZE;
 433         sb->s_blocksize         = PAGE_SIZE;
 434         sb->s_blocksize_bits    = PAGE_SHIFT;
 435         sb->s_magic             = PSTOREFS_MAGIC;
 436         sb->s_op                = &pstore_ops;
 437         sb->s_time_gran         = 1;
 438
 439         parse_options(data);
 440
 441         inode = pstore_get_inode(sb);
 442         if (inode) {
 443                 inode->i_mode = S_IFDIR | 0750;
 444                 inode->i_op = &pstore_dir_inode_operations;
 445                 inode->i_fop = &simple_dir_operations;
 446                 inc_nlink(inode);
 447         }
 448         sb->s_root = d_make_root(inode);
 449         if (!sb->s_root)
 450                 return -ENOMEM;
 451
 452         mutex_lock(&pstore_sb_lock);
 453         pstore_sb = sb;
 454         mutex_unlock(&pstore_sb_lock);
 455
 456         pstore_get_records(0);
 457
 458         return 0;
 459 }
 460
 461 static struct dentry *pstore_mount(struct file_system_type *fs_type,
 462         int flags, const char *dev_name, void *data)
 463 {
 464         return mount_single(fs_type, flags, data, pstore_fill_super);
 465 }
 466
 467 static void pstore_kill_sb(struct super_block *sb)
 468 {
 469         mutex_lock(&pstore_sb_lock);
 470         WARN_ON(pstore_sb != sb);
 471
 472         kill_litter_super(sb);
 473         pstore_sb = NULL;
 474
 475         mutex_lock(&records_list_lock);
 476         INIT_LIST_HEAD(&records_list);
 477         mutex_unlock(&records_list_lock);
 478
 479         mutex_unlock(&pstore_sb_lock);
 480 }
 481
 482 static struct file_system_type pstore_fs_type = {
 483         .owner          = THIS_MODULE,
 484         .name           = "pstore",
 485         .mount          = pstore_mount,
 486         .kill_sb        = pstore_kill_sb,
 487 };
 488
 489 int __init pstore_init_fs(void)
 490 {
 491         int err;
 492
 493         /* Create a convenient mount point for people to access pstore */
 494         err = sysfs_create_mount_point(fs_kobj, "pstore");
 495         if (err)
 496                 goto out;
 497
 498         err = register_filesystem(&pstore_fs_type);
 499         if (err < 0)
 500                 sysfs_remove_mount_point(fs_kobj, "pstore");
 501
 502 out:
 503         return err;
 504 }
 505
 506 void __exit pstore_exit_fs(void)
 507 {
 508         unregister_filesystem(&pstore_fs_type);
 509         sysfs_remove_mount_point(fs_kobj, "pstore");
 510 }