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_record *record; 50 size_t total_size; 51 }; 52 53 struct pstore_ftrace_seq_data { 54 const void *ptr; 55 size_t off; 56 size_t size; 57 }; 58 59 #define REC_SIZE sizeof(struct pstore_ftrace_record) 60 61 static void free_pstore_private(struct pstore_private *private) 62 { 63 if (!private) 64 return; 65 if (private->record) { 66 kfree(private->record->buf); 67 kfree(private->record); 68 } 69 kfree(private); 70 } 71 72 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos) 73 { 74 struct pstore_private *ps = s->private; 75 struct pstore_ftrace_seq_data *data; 76 77 data = kzalloc(sizeof(*data), GFP_KERNEL); 78 if (!data) 79 return NULL; 80 81 data->off = ps->total_size % REC_SIZE; 82 data->off += *pos * REC_SIZE; 83 if (data->off + REC_SIZE > ps->total_size) { 84 kfree(data); 85 return NULL; 86 } 87 88 return data; 89 90 } 91 92 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v) 93 { 94 kfree(v); 95 } 96 97 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos) 98 { 99 struct pstore_private *ps = s->private; 100 struct pstore_ftrace_seq_data *data = v; 101 102 data->off += REC_SIZE; 103 if (data->off + REC_SIZE > ps->total_size) 104 return NULL; 105 106 (*pos)++; 107 return data; 108 } 109 110 static int pstore_ftrace_seq_show(struct seq_file *s, void *v) 111 { 112 struct pstore_private *ps = s->private; 113 struct pstore_ftrace_seq_data *data = v; 114 struct pstore_ftrace_record *rec; 115 116 rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off); 117 118 seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %pf <- %pF\n", 119 pstore_ftrace_decode_cpu(rec), 120 pstore_ftrace_read_timestamp(rec), 121 rec->ip, rec->parent_ip, (void *)rec->ip, 122 (void *)rec->parent_ip); 123 124 return 0; 125 } 126 127 static const struct seq_operations pstore_ftrace_seq_ops = { 128 .start = pstore_ftrace_seq_start, 129 .next = pstore_ftrace_seq_next, 130 .stop = pstore_ftrace_seq_stop, 131 .show = pstore_ftrace_seq_show, 132 }; 133 134 static ssize_t pstore_file_read(struct file *file, char __user *userbuf, 135 size_t count, loff_t *ppos) 136 { 137 struct seq_file *sf = file->private_data; 138 struct pstore_private *ps = sf->private; 139 140 if (ps->record->type == PSTORE_TYPE_FTRACE) 141 return seq_read(file, userbuf, count, ppos); 142 return simple_read_from_buffer(userbuf, count, ppos, 143 ps->record->buf, ps->total_size); 144 } 145 146 static int pstore_file_open(struct inode *inode, struct file *file) 147 { 148 struct pstore_private *ps = inode->i_private; 149 struct seq_file *sf; 150 int err; 151 const struct seq_operations *sops = NULL; 152 153 if (ps->record->type == PSTORE_TYPE_FTRACE) 154 sops = &pstore_ftrace_seq_ops; 155 156 err = seq_open(file, sops); 157 if (err < 0) 158 return err; 159 160 sf = file->private_data; 161 sf->private = ps; 162 163 return 0; 164 } 165 166 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence) 167 { 168 struct seq_file *sf = file->private_data; 169 170 if (sf->op) 171 return seq_lseek(file, off, whence); 172 return default_llseek(file, off, whence); 173 } 174 175 static const struct file_operations pstore_file_operations = { 176 .open = pstore_file_open, 177 .read = pstore_file_read, 178 .llseek = pstore_file_llseek, 179 .release = seq_release, 180 }; 181 182 /* 183 * When a file is unlinked from our file system we call the 184 * platform driver to erase the record from persistent store. 185 */ 186 static int pstore_unlink(struct inode *dir, struct dentry *dentry) 187 { 188 struct pstore_private *p = d_inode(dentry)->i_private; 189 struct pstore_record *record = p->record; 190 191 if (!record->psi->erase) 192 return -EPERM; 193 194 mutex_lock(&record->psi->read_mutex); 195 record->psi->erase(record); 196 mutex_unlock(&record->psi->read_mutex); 197 198 return simple_unlink(dir, dentry); 199 } 200 201 static void pstore_evict_inode(struct inode *inode) 202 { 203 struct pstore_private *p = inode->i_private; 204 unsigned long flags; 205 206 clear_inode(inode); 207 if (p) { 208 spin_lock_irqsave(&allpstore_lock, flags); 209 list_del(&p->list); 210 spin_unlock_irqrestore(&allpstore_lock, flags); 211 free_pstore_private(p); 212 } 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 super_block *pstore_sb; 291 292 bool pstore_is_mounted(void) 293 { 294 return pstore_sb != NULL; 295 } 296 297 /* 298 * Make a regular file in the root directory of our file system. 299 * Load it up with "size" bytes of data from "buf". 300 * Set the mtime & ctime to the date that this record was originally stored. 301 */ 302 int pstore_mkfile(struct dentry *root, struct pstore_record *record) 303 { 304 struct dentry *dentry; 305 struct inode *inode; 306 int rc = 0; 307 char name[PSTORE_NAMELEN]; 308 struct pstore_private *private, *pos; 309 unsigned long flags; 310 size_t size = record->size + record->ecc_notice_size; 311 312 WARN_ON(!inode_is_locked(d_inode(root))); 313 314 spin_lock_irqsave(&allpstore_lock, flags); 315 list_for_each_entry(pos, &allpstore, list) { 316 if (pos->record->type == record->type && 317 pos->record->id == record->id && 318 pos->record->psi == record->psi) { 319 rc = -EEXIST; 320 break; 321 } 322 } 323 spin_unlock_irqrestore(&allpstore_lock, flags); 324 if (rc) 325 return rc; 326 327 rc = -ENOMEM; 328 inode = pstore_get_inode(root->d_sb); 329 if (!inode) 330 goto fail; 331 inode->i_mode = S_IFREG | 0444; 332 inode->i_fop = &pstore_file_operations; 333 private = kzalloc(sizeof(*private), GFP_KERNEL); 334 if (!private) 335 goto fail_alloc; 336 private->record = record; 337 338 scnprintf(name, sizeof(name), "%s-%s-%llu%s", 339 pstore_type_to_name(record->type), 340 record->psi->name, record->id, 341 record->compressed ? ".enc.z" : ""); 342 343 dentry = d_alloc_name(root, name); 344 if (!dentry) 345 goto fail_private; 346 347 inode->i_size = private->total_size = size; 348 349 inode->i_private = private; 350 351 if (record->time.tv_sec) 352 inode->i_mtime = inode->i_ctime = record->time; 353 354 d_add(dentry, inode); 355 356 spin_lock_irqsave(&allpstore_lock, flags); 357 list_add(&private->list, &allpstore); 358 spin_unlock_irqrestore(&allpstore_lock, flags); 359 360 return 0; 361 362 fail_private: 363 free_pstore_private(private); 364 fail_alloc: 365 iput(inode); 366 367 fail: 368 return rc; 369 } 370 371 /* 372 * Read all the records from the persistent store. Create 373 * files in our filesystem. Don't warn about -EEXIST errors 374 * when we are re-scanning the backing store looking to add new 375 * error records. 376 */ 377 void pstore_get_records(int quiet) 378 { 379 struct pstore_info *psi = psinfo; 380 struct dentry *root; 381 382 if (!psi || !pstore_sb) 383 return; 384 385 root = pstore_sb->s_root; 386 387 inode_lock(d_inode(root)); 388 pstore_get_backend_records(psi, root, quiet); 389 inode_unlock(d_inode(root)); 390 } 391 392 static int pstore_fill_super(struct super_block *sb, void *data, int silent) 393 { 394 struct inode *inode; 395 396 pstore_sb = sb; 397 398 sb->s_maxbytes = MAX_LFS_FILESIZE; 399 sb->s_blocksize = PAGE_SIZE; 400 sb->s_blocksize_bits = PAGE_SHIFT; 401 sb->s_magic = PSTOREFS_MAGIC; 402 sb->s_op = &pstore_ops; 403 sb->s_time_gran = 1; 404 405 parse_options(data); 406 407 inode = pstore_get_inode(sb); 408 if (inode) { 409 inode->i_mode = S_IFDIR | 0750; 410 inode->i_op = &pstore_dir_inode_operations; 411 inode->i_fop = &simple_dir_operations; 412 inc_nlink(inode); 413 } 414 sb->s_root = d_make_root(inode); 415 if (!sb->s_root) 416 return -ENOMEM; 417 418 pstore_get_records(0); 419 420 return 0; 421 } 422 423 static struct dentry *pstore_mount(struct file_system_type *fs_type, 424 int flags, const char *dev_name, void *data) 425 { 426 return mount_single(fs_type, flags, data, pstore_fill_super); 427 } 428 429 static void pstore_kill_sb(struct super_block *sb) 430 { 431 kill_litter_super(sb); 432 pstore_sb = NULL; 433 } 434 435 static struct file_system_type pstore_fs_type = { 436 .owner = THIS_MODULE, 437 .name = "pstore", 438 .mount = pstore_mount, 439 .kill_sb = pstore_kill_sb, 440 }; 441 442 int __init pstore_init_fs(void) 443 { 444 int err; 445 446 /* Create a convenient mount point for people to access pstore */ 447 err = sysfs_create_mount_point(fs_kobj, "pstore"); 448 if (err) 449 goto out; 450 451 err = register_filesystem(&pstore_fs_type); 452 if (err < 0) 453 sysfs_remove_mount_point(fs_kobj, "pstore"); 454 455 out: 456 return err; 457 } 458 459 void __exit pstore_exit_fs(void) 460 { 461 unregister_filesystem(&pstore_fs_type); 462 sysfs_remove_mount_point(fs_kobj, "pstore"); 463 } 464