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