1 /* 2 * (C) 1997 Linus Torvalds 3 * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation) 4 */ 5 #include <linux/fs.h> 6 #include <linux/mm.h> 7 #include <linux/dcache.h> 8 #include <linux/init.h> 9 #include <linux/slab.h> 10 #include <linux/writeback.h> 11 #include <linux/module.h> 12 #include <linux/backing-dev.h> 13 #include <linux/wait.h> 14 #include <linux/rwsem.h> 15 #include <linux/hash.h> 16 #include <linux/swap.h> 17 #include <linux/security.h> 18 #include <linux/pagemap.h> 19 #include <linux/cdev.h> 20 #include <linux/bootmem.h> 21 #include <linux/fsnotify.h> 22 #include <linux/mount.h> 23 #include <linux/async.h> 24 #include <linux/posix_acl.h> 25 #include <linux/prefetch.h> 26 #include <linux/ima.h> 27 #include <linux/cred.h> 28 #include <linux/buffer_head.h> /* for inode_has_buffers */ 29 #include "internal.h" 30 31 /* 32 * Inode locking rules: 33 * 34 * inode->i_lock protects: 35 * inode->i_state, inode->i_hash, __iget() 36 * inode_lru_lock protects: 37 * inode_lru, inode->i_lru 38 * inode_sb_list_lock protects: 39 * sb->s_inodes, inode->i_sb_list 40 * inode_wb_list_lock protects: 41 * bdi->wb.b_{dirty,io,more_io}, inode->i_wb_list 42 * inode_hash_lock protects: 43 * inode_hashtable, inode->i_hash 44 * 45 * Lock ordering: 46 * 47 * inode_sb_list_lock 48 * inode->i_lock 49 * inode_lru_lock 50 * 51 * inode_wb_list_lock 52 * inode->i_lock 53 * 54 * inode_hash_lock 55 * inode_sb_list_lock 56 * inode->i_lock 57 * 58 * iunique_lock 59 * inode_hash_lock 60 */ 61 62 static unsigned int i_hash_mask __read_mostly; 63 static unsigned int i_hash_shift __read_mostly; 64 static struct hlist_head *inode_hashtable __read_mostly; 65 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock); 66 67 static LIST_HEAD(inode_lru); 68 static DEFINE_SPINLOCK(inode_lru_lock); 69 70 __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_sb_list_lock); 71 __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_wb_list_lock); 72 73 /* 74 * iprune_sem provides exclusion between the icache shrinking and the 75 * umount path. 76 * 77 * We don't actually need it to protect anything in the umount path, 78 * but only need to cycle through it to make sure any inode that 79 * prune_icache took off the LRU list has been fully torn down by the 80 * time we are past evict_inodes. 81 */ 82 static DECLARE_RWSEM(iprune_sem); 83 84 /* 85 * Empty aops. Can be used for the cases where the user does not 86 * define any of the address_space operations. 87 */ 88 const struct address_space_operations empty_aops = { 89 }; 90 EXPORT_SYMBOL(empty_aops); 91 92 /* 93 * Statistics gathering.. 94 */ 95 struct inodes_stat_t inodes_stat; 96 97 static DEFINE_PER_CPU(unsigned int, nr_inodes); 98 99 static struct kmem_cache *inode_cachep __read_mostly; 100 101 static int get_nr_inodes(void) 102 { 103 int i; 104 int sum = 0; 105 for_each_possible_cpu(i) 106 sum += per_cpu(nr_inodes, i); 107 return sum < 0 ? 0 : sum; 108 } 109 110 static inline int get_nr_inodes_unused(void) 111 { 112 return inodes_stat.nr_unused; 113 } 114 115 int get_nr_dirty_inodes(void) 116 { 117 /* not actually dirty inodes, but a wild approximation */ 118 int nr_dirty = get_nr_inodes() - get_nr_inodes_unused(); 119 return nr_dirty > 0 ? nr_dirty : 0; 120 } 121 122 /* 123 * Handle nr_inode sysctl 124 */ 125 #ifdef CONFIG_SYSCTL 126 int proc_nr_inodes(ctl_table *table, int write, 127 void __user *buffer, size_t *lenp, loff_t *ppos) 128 { 129 inodes_stat.nr_inodes = get_nr_inodes(); 130 return proc_dointvec(table, write, buffer, lenp, ppos); 131 } 132 #endif 133 134 /** 135 * inode_init_always - perform inode structure intialisation 136 * @sb: superblock inode belongs to 137 * @inode: inode to initialise 138 * 139 * These are initializations that need to be done on every inode 140 * allocation as the fields are not initialised by slab allocation. 141 */ 142 int inode_init_always(struct super_block *sb, struct inode *inode) 143 { 144 static const struct inode_operations empty_iops; 145 static const struct file_operations empty_fops; 146 struct address_space *const mapping = &inode->i_data; 147 148 inode->i_sb = sb; 149 inode->i_blkbits = sb->s_blocksize_bits; 150 inode->i_flags = 0; 151 atomic_set(&inode->i_count, 1); 152 inode->i_op = &empty_iops; 153 inode->i_fop = &empty_fops; 154 inode->i_nlink = 1; 155 inode->i_uid = 0; 156 inode->i_gid = 0; 157 atomic_set(&inode->i_writecount, 0); 158 inode->i_size = 0; 159 inode->i_blocks = 0; 160 inode->i_bytes = 0; 161 inode->i_generation = 0; 162 #ifdef CONFIG_QUOTA 163 memset(&inode->i_dquot, 0, sizeof(inode->i_dquot)); 164 #endif 165 inode->i_pipe = NULL; 166 inode->i_bdev = NULL; 167 inode->i_cdev = NULL; 168 inode->i_rdev = 0; 169 inode->dirtied_when = 0; 170 171 if (security_inode_alloc(inode)) 172 goto out; 173 spin_lock_init(&inode->i_lock); 174 lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key); 175 176 mutex_init(&inode->i_mutex); 177 lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key); 178 179 init_rwsem(&inode->i_alloc_sem); 180 lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key); 181 182 mapping->a_ops = &empty_aops; 183 mapping->host = inode; 184 mapping->flags = 0; 185 mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE); 186 mapping->assoc_mapping = NULL; 187 mapping->backing_dev_info = &default_backing_dev_info; 188 mapping->writeback_index = 0; 189 190 /* 191 * If the block_device provides a backing_dev_info for client 192 * inodes then use that. Otherwise the inode share the bdev's 193 * backing_dev_info. 194 */ 195 if (sb->s_bdev) { 196 struct backing_dev_info *bdi; 197 198 bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info; 199 mapping->backing_dev_info = bdi; 200 } 201 inode->i_private = NULL; 202 inode->i_mapping = mapping; 203 #ifdef CONFIG_FS_POSIX_ACL 204 inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED; 205 #endif 206 207 #ifdef CONFIG_FSNOTIFY 208 inode->i_fsnotify_mask = 0; 209 #endif 210 211 this_cpu_inc(nr_inodes); 212 213 return 0; 214 out: 215 return -ENOMEM; 216 } 217 EXPORT_SYMBOL(inode_init_always); 218 219 static struct inode *alloc_inode(struct super_block *sb) 220 { 221 struct inode *inode; 222 223 if (sb->s_op->alloc_inode) 224 inode = sb->s_op->alloc_inode(sb); 225 else 226 inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL); 227 228 if (!inode) 229 return NULL; 230 231 if (unlikely(inode_init_always(sb, inode))) { 232 if (inode->i_sb->s_op->destroy_inode) 233 inode->i_sb->s_op->destroy_inode(inode); 234 else 235 kmem_cache_free(inode_cachep, inode); 236 return NULL; 237 } 238 239 return inode; 240 } 241 242 void free_inode_nonrcu(struct inode *inode) 243 { 244 kmem_cache_free(inode_cachep, inode); 245 } 246 EXPORT_SYMBOL(free_inode_nonrcu); 247 248 void __destroy_inode(struct inode *inode) 249 { 250 BUG_ON(inode_has_buffers(inode)); 251 security_inode_free(inode); 252 fsnotify_inode_delete(inode); 253 #ifdef CONFIG_FS_POSIX_ACL 254 if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED) 255 posix_acl_release(inode->i_acl); 256 if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED) 257 posix_acl_release(inode->i_default_acl); 258 #endif 259 this_cpu_dec(nr_inodes); 260 } 261 EXPORT_SYMBOL(__destroy_inode); 262 263 static void i_callback(struct rcu_head *head) 264 { 265 struct inode *inode = container_of(head, struct inode, i_rcu); 266 INIT_LIST_HEAD(&inode->i_dentry); 267 kmem_cache_free(inode_cachep, inode); 268 } 269 270 static void destroy_inode(struct inode *inode) 271 { 272 BUG_ON(!list_empty(&inode->i_lru)); 273 __destroy_inode(inode); 274 if (inode->i_sb->s_op->destroy_inode) 275 inode->i_sb->s_op->destroy_inode(inode); 276 else 277 call_rcu(&inode->i_rcu, i_callback); 278 } 279 280 void address_space_init_once(struct address_space *mapping) 281 { 282 memset(mapping, 0, sizeof(*mapping)); 283 INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC); 284 spin_lock_init(&mapping->tree_lock); 285 mutex_init(&mapping->i_mmap_mutex); 286 INIT_LIST_HEAD(&mapping->private_list); 287 spin_lock_init(&mapping->private_lock); 288 INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap); 289 INIT_LIST_HEAD(&mapping->i_mmap_nonlinear); 290 } 291 EXPORT_SYMBOL(address_space_init_once); 292 293 /* 294 * These are initializations that only need to be done 295 * once, because the fields are idempotent across use 296 * of the inode, so let the slab aware of that. 297 */ 298 void inode_init_once(struct inode *inode) 299 { 300 memset(inode, 0, sizeof(*inode)); 301 INIT_HLIST_NODE(&inode->i_hash); 302 INIT_LIST_HEAD(&inode->i_dentry); 303 INIT_LIST_HEAD(&inode->i_devices); 304 INIT_LIST_HEAD(&inode->i_wb_list); 305 INIT_LIST_HEAD(&inode->i_lru); 306 address_space_init_once(&inode->i_data); 307 i_size_ordered_init(inode); 308 #ifdef CONFIG_FSNOTIFY 309 INIT_HLIST_HEAD(&inode->i_fsnotify_marks); 310 #endif 311 } 312 EXPORT_SYMBOL(inode_init_once); 313 314 static void init_once(void *foo) 315 { 316 struct inode *inode = (struct inode *) foo; 317 318 inode_init_once(inode); 319 } 320 321 /* 322 * inode->i_lock must be held 323 */ 324 void __iget(struct inode *inode) 325 { 326 atomic_inc(&inode->i_count); 327 } 328 329 /* 330 * get additional reference to inode; caller must already hold one. 331 */ 332 void ihold(struct inode *inode) 333 { 334 WARN_ON(atomic_inc_return(&inode->i_count) < 2); 335 } 336 EXPORT_SYMBOL(ihold); 337 338 static void inode_lru_list_add(struct inode *inode) 339 { 340 spin_lock(&inode_lru_lock); 341 if (list_empty(&inode->i_lru)) { 342 list_add(&inode->i_lru, &inode_lru); 343 inodes_stat.nr_unused++; 344 } 345 spin_unlock(&inode_lru_lock); 346 } 347 348 static void inode_lru_list_del(struct inode *inode) 349 { 350 spin_lock(&inode_lru_lock); 351 if (!list_empty(&inode->i_lru)) { 352 list_del_init(&inode->i_lru); 353 inodes_stat.nr_unused--; 354 } 355 spin_unlock(&inode_lru_lock); 356 } 357 358 /** 359 * inode_sb_list_add - add inode to the superblock list of inodes 360 * @inode: inode to add 361 */ 362 void inode_sb_list_add(struct inode *inode) 363 { 364 spin_lock(&inode_sb_list_lock); 365 list_add(&inode->i_sb_list, &inode->i_sb->s_inodes); 366 spin_unlock(&inode_sb_list_lock); 367 } 368 EXPORT_SYMBOL_GPL(inode_sb_list_add); 369 370 static inline void inode_sb_list_del(struct inode *inode) 371 { 372 spin_lock(&inode_sb_list_lock); 373 list_del_init(&inode->i_sb_list); 374 spin_unlock(&inode_sb_list_lock); 375 } 376 377 static unsigned long hash(struct super_block *sb, unsigned long hashval) 378 { 379 unsigned long tmp; 380 381 tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) / 382 L1_CACHE_BYTES; 383 tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift); 384 return tmp & i_hash_mask; 385 } 386 387 /** 388 * __insert_inode_hash - hash an inode 389 * @inode: unhashed inode 390 * @hashval: unsigned long value used to locate this object in the 391 * inode_hashtable. 392 * 393 * Add an inode to the inode hash for this superblock. 394 */ 395 void __insert_inode_hash(struct inode *inode, unsigned long hashval) 396 { 397 struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval); 398 399 spin_lock(&inode_hash_lock); 400 spin_lock(&inode->i_lock); 401 hlist_add_head(&inode->i_hash, b); 402 spin_unlock(&inode->i_lock); 403 spin_unlock(&inode_hash_lock); 404 } 405 EXPORT_SYMBOL(__insert_inode_hash); 406 407 /** 408 * remove_inode_hash - remove an inode from the hash 409 * @inode: inode to unhash 410 * 411 * Remove an inode from the superblock. 412 */ 413 void remove_inode_hash(struct inode *inode) 414 { 415 spin_lock(&inode_hash_lock); 416 spin_lock(&inode->i_lock); 417 hlist_del_init(&inode->i_hash); 418 spin_unlock(&inode->i_lock); 419 spin_unlock(&inode_hash_lock); 420 } 421 EXPORT_SYMBOL(remove_inode_hash); 422 423 void end_writeback(struct inode *inode) 424 { 425 might_sleep(); 426 /* 427 * We have to cycle tree_lock here because reclaim can be still in the 428 * process of removing the last page (in __delete_from_page_cache()) 429 * and we must not free mapping under it. 430 */ 431 spin_lock_irq(&inode->i_data.tree_lock); 432 BUG_ON(inode->i_data.nrpages); 433 spin_unlock_irq(&inode->i_data.tree_lock); 434 BUG_ON(!list_empty(&inode->i_data.private_list)); 435 BUG_ON(!(inode->i_state & I_FREEING)); 436 BUG_ON(inode->i_state & I_CLEAR); 437 inode_sync_wait(inode); 438 /* don't need i_lock here, no concurrent mods to i_state */ 439 inode->i_state = I_FREEING | I_CLEAR; 440 } 441 EXPORT_SYMBOL(end_writeback); 442 443 /* 444 * Free the inode passed in, removing it from the lists it is still connected 445 * to. We remove any pages still attached to the inode and wait for any IO that 446 * is still in progress before finally destroying the inode. 447 * 448 * An inode must already be marked I_FREEING so that we avoid the inode being 449 * moved back onto lists if we race with other code that manipulates the lists 450 * (e.g. writeback_single_inode). The caller is responsible for setting this. 451 * 452 * An inode must already be removed from the LRU list before being evicted from 453 * the cache. This should occur atomically with setting the I_FREEING state 454 * flag, so no inodes here should ever be on the LRU when being evicted. 455 */ 456 static void evict(struct inode *inode) 457 { 458 const struct super_operations *op = inode->i_sb->s_op; 459 460 BUG_ON(!(inode->i_state & I_FREEING)); 461 BUG_ON(!list_empty(&inode->i_lru)); 462 463 inode_wb_list_del(inode); 464 inode_sb_list_del(inode); 465 466 if (op->evict_inode) { 467 op->evict_inode(inode); 468 } else { 469 if (inode->i_data.nrpages) 470 truncate_inode_pages(&inode->i_data, 0); 471 end_writeback(inode); 472 } 473 if (S_ISBLK(inode->i_mode) && inode->i_bdev) 474 bd_forget(inode); 475 if (S_ISCHR(inode->i_mode) && inode->i_cdev) 476 cd_forget(inode); 477 478 remove_inode_hash(inode); 479 480 spin_lock(&inode->i_lock); 481 wake_up_bit(&inode->i_state, __I_NEW); 482 BUG_ON(inode->i_state != (I_FREEING | I_CLEAR)); 483 spin_unlock(&inode->i_lock); 484 485 destroy_inode(inode); 486 } 487 488 /* 489 * dispose_list - dispose of the contents of a local list 490 * @head: the head of the list to free 491 * 492 * Dispose-list gets a local list with local inodes in it, so it doesn't 493 * need to worry about list corruption and SMP locks. 494 */ 495 static void dispose_list(struct list_head *head) 496 { 497 while (!list_empty(head)) { 498 struct inode *inode; 499 500 inode = list_first_entry(head, struct inode, i_lru); 501 list_del_init(&inode->i_lru); 502 503 evict(inode); 504 } 505 } 506 507 /** 508 * evict_inodes - evict all evictable inodes for a superblock 509 * @sb: superblock to operate on 510 * 511 * Make sure that no inodes with zero refcount are retained. This is 512 * called by superblock shutdown after having MS_ACTIVE flag removed, 513 * so any inode reaching zero refcount during or after that call will 514 * be immediately evicted. 515 */ 516 void evict_inodes(struct super_block *sb) 517 { 518 struct inode *inode, *next; 519 LIST_HEAD(dispose); 520 521 spin_lock(&inode_sb_list_lock); 522 list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) { 523 if (atomic_read(&inode->i_count)) 524 continue; 525 526 spin_lock(&inode->i_lock); 527 if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { 528 spin_unlock(&inode->i_lock); 529 continue; 530 } 531 532 inode->i_state |= I_FREEING; 533 inode_lru_list_del(inode); 534 spin_unlock(&inode->i_lock); 535 list_add(&inode->i_lru, &dispose); 536 } 537 spin_unlock(&inode_sb_list_lock); 538 539 dispose_list(&dispose); 540 541 /* 542 * Cycle through iprune_sem to make sure any inode that prune_icache 543 * moved off the list before we took the lock has been fully torn 544 * down. 545 */ 546 down_write(&iprune_sem); 547 up_write(&iprune_sem); 548 } 549 550 /** 551 * invalidate_inodes - attempt to free all inodes on a superblock 552 * @sb: superblock to operate on 553 * @kill_dirty: flag to guide handling of dirty inodes 554 * 555 * Attempts to free all inodes for a given superblock. If there were any 556 * busy inodes return a non-zero value, else zero. 557 * If @kill_dirty is set, discard dirty inodes too, otherwise treat 558 * them as busy. 559 */ 560 int invalidate_inodes(struct super_block *sb, bool kill_dirty) 561 { 562 int busy = 0; 563 struct inode *inode, *next; 564 LIST_HEAD(dispose); 565 566 spin_lock(&inode_sb_list_lock); 567 list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) { 568 spin_lock(&inode->i_lock); 569 if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { 570 spin_unlock(&inode->i_lock); 571 continue; 572 } 573 if (inode->i_state & I_DIRTY && !kill_dirty) { 574 spin_unlock(&inode->i_lock); 575 busy = 1; 576 continue; 577 } 578 if (atomic_read(&inode->i_count)) { 579 spin_unlock(&inode->i_lock); 580 busy = 1; 581 continue; 582 } 583 584 inode->i_state |= I_FREEING; 585 inode_lru_list_del(inode); 586 spin_unlock(&inode->i_lock); 587 list_add(&inode->i_lru, &dispose); 588 } 589 spin_unlock(&inode_sb_list_lock); 590 591 dispose_list(&dispose); 592 593 return busy; 594 } 595 596 static int can_unuse(struct inode *inode) 597 { 598 if (inode->i_state & ~I_REFERENCED) 599 return 0; 600 if (inode_has_buffers(inode)) 601 return 0; 602 if (atomic_read(&inode->i_count)) 603 return 0; 604 if (inode->i_data.nrpages) 605 return 0; 606 return 1; 607 } 608 609 /* 610 * Scan `goal' inodes on the unused list for freeable ones. They are moved to a 611 * temporary list and then are freed outside inode_lru_lock by dispose_list(). 612 * 613 * Any inodes which are pinned purely because of attached pagecache have their 614 * pagecache removed. If the inode has metadata buffers attached to 615 * mapping->private_list then try to remove them. 616 * 617 * If the inode has the I_REFERENCED flag set, then it means that it has been 618 * used recently - the flag is set in iput_final(). When we encounter such an 619 * inode, clear the flag and move it to the back of the LRU so it gets another 620 * pass through the LRU before it gets reclaimed. This is necessary because of 621 * the fact we are doing lazy LRU updates to minimise lock contention so the 622 * LRU does not have strict ordering. Hence we don't want to reclaim inodes 623 * with this flag set because they are the inodes that are out of order. 624 */ 625 static void prune_icache(int nr_to_scan) 626 { 627 LIST_HEAD(freeable); 628 int nr_scanned; 629 unsigned long reap = 0; 630 631 down_read(&iprune_sem); 632 spin_lock(&inode_lru_lock); 633 for (nr_scanned = 0; nr_scanned < nr_to_scan; nr_scanned++) { 634 struct inode *inode; 635 636 if (list_empty(&inode_lru)) 637 break; 638 639 inode = list_entry(inode_lru.prev, struct inode, i_lru); 640 641 /* 642 * we are inverting the inode_lru_lock/inode->i_lock here, 643 * so use a trylock. If we fail to get the lock, just move the 644 * inode to the back of the list so we don't spin on it. 645 */ 646 if (!spin_trylock(&inode->i_lock)) { 647 list_move(&inode->i_lru, &inode_lru); 648 continue; 649 } 650 651 /* 652 * Referenced or dirty inodes are still in use. Give them 653 * another pass through the LRU as we canot reclaim them now. 654 */ 655 if (atomic_read(&inode->i_count) || 656 (inode->i_state & ~I_REFERENCED)) { 657 list_del_init(&inode->i_lru); 658 spin_unlock(&inode->i_lock); 659 inodes_stat.nr_unused--; 660 continue; 661 } 662 663 /* recently referenced inodes get one more pass */ 664 if (inode->i_state & I_REFERENCED) { 665 inode->i_state &= ~I_REFERENCED; 666 list_move(&inode->i_lru, &inode_lru); 667 spin_unlock(&inode->i_lock); 668 continue; 669 } 670 if (inode_has_buffers(inode) || inode->i_data.nrpages) { 671 __iget(inode); 672 spin_unlock(&inode->i_lock); 673 spin_unlock(&inode_lru_lock); 674 if (remove_inode_buffers(inode)) 675 reap += invalidate_mapping_pages(&inode->i_data, 676 0, -1); 677 iput(inode); 678 spin_lock(&inode_lru_lock); 679 680 if (inode != list_entry(inode_lru.next, 681 struct inode, i_lru)) 682 continue; /* wrong inode or list_empty */ 683 /* avoid lock inversions with trylock */ 684 if (!spin_trylock(&inode->i_lock)) 685 continue; 686 if (!can_unuse(inode)) { 687 spin_unlock(&inode->i_lock); 688 continue; 689 } 690 } 691 WARN_ON(inode->i_state & I_NEW); 692 inode->i_state |= I_FREEING; 693 spin_unlock(&inode->i_lock); 694 695 list_move(&inode->i_lru, &freeable); 696 inodes_stat.nr_unused--; 697 } 698 if (current_is_kswapd()) 699 __count_vm_events(KSWAPD_INODESTEAL, reap); 700 else 701 __count_vm_events(PGINODESTEAL, reap); 702 spin_unlock(&inode_lru_lock); 703 704 dispose_list(&freeable); 705 up_read(&iprune_sem); 706 } 707 708 /* 709 * shrink_icache_memory() will attempt to reclaim some unused inodes. Here, 710 * "unused" means that no dentries are referring to the inodes: the files are 711 * not open and the dcache references to those inodes have already been 712 * reclaimed. 713 * 714 * This function is passed the number of inodes to scan, and it returns the 715 * total number of remaining possibly-reclaimable inodes. 716 */ 717 static int shrink_icache_memory(struct shrinker *shrink, 718 struct shrink_control *sc) 719 { 720 int nr = sc->nr_to_scan; 721 gfp_t gfp_mask = sc->gfp_mask; 722 723 if (nr) { 724 /* 725 * Nasty deadlock avoidance. We may hold various FS locks, 726 * and we don't want to recurse into the FS that called us 727 * in clear_inode() and friends.. 728 */ 729 if (!(gfp_mask & __GFP_FS)) 730 return -1; 731 prune_icache(nr); 732 } 733 return (get_nr_inodes_unused() / 100) * sysctl_vfs_cache_pressure; 734 } 735 736 static struct shrinker icache_shrinker = { 737 .shrink = shrink_icache_memory, 738 .seeks = DEFAULT_SEEKS, 739 }; 740 741 static void __wait_on_freeing_inode(struct inode *inode); 742 /* 743 * Called with the inode lock held. 744 */ 745 static struct inode *find_inode(struct super_block *sb, 746 struct hlist_head *head, 747 int (*test)(struct inode *, void *), 748 void *data) 749 { 750 struct hlist_node *node; 751 struct inode *inode = NULL; 752 753 repeat: 754 hlist_for_each_entry(inode, node, head, i_hash) { 755 spin_lock(&inode->i_lock); 756 if (inode->i_sb != sb) { 757 spin_unlock(&inode->i_lock); 758 continue; 759 } 760 if (!test(inode, data)) { 761 spin_unlock(&inode->i_lock); 762 continue; 763 } 764 if (inode->i_state & (I_FREEING|I_WILL_FREE)) { 765 __wait_on_freeing_inode(inode); 766 goto repeat; 767 } 768 __iget(inode); 769 spin_unlock(&inode->i_lock); 770 return inode; 771 } 772 return NULL; 773 } 774 775 /* 776 * find_inode_fast is the fast path version of find_inode, see the comment at 777 * iget_locked for details. 778 */ 779 static struct inode *find_inode_fast(struct super_block *sb, 780 struct hlist_head *head, unsigned long ino) 781 { 782 struct hlist_node *node; 783 struct inode *inode = NULL; 784 785 repeat: 786 hlist_for_each_entry(inode, node, head, i_hash) { 787 spin_lock(&inode->i_lock); 788 if (inode->i_ino != ino) { 789 spin_unlock(&inode->i_lock); 790 continue; 791 } 792 if (inode->i_sb != sb) { 793 spin_unlock(&inode->i_lock); 794 continue; 795 } 796 if (inode->i_state & (I_FREEING|I_WILL_FREE)) { 797 __wait_on_freeing_inode(inode); 798 goto repeat; 799 } 800 __iget(inode); 801 spin_unlock(&inode->i_lock); 802 return inode; 803 } 804 return NULL; 805 } 806 807 /* 808 * Each cpu owns a range of LAST_INO_BATCH numbers. 809 * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations, 810 * to renew the exhausted range. 811 * 812 * This does not significantly increase overflow rate because every CPU can 813 * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is 814 * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the 815 * 2^32 range, and is a worst-case. Even a 50% wastage would only increase 816 * overflow rate by 2x, which does not seem too significant. 817 * 818 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW 819 * error if st_ino won't fit in target struct field. Use 32bit counter 820 * here to attempt to avoid that. 821 */ 822 #define LAST_INO_BATCH 1024 823 static DEFINE_PER_CPU(unsigned int, last_ino); 824 825 unsigned int get_next_ino(void) 826 { 827 unsigned int *p = &get_cpu_var(last_ino); 828 unsigned int res = *p; 829 830 #ifdef CONFIG_SMP 831 if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) { 832 static atomic_t shared_last_ino; 833 int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino); 834 835 res = next - LAST_INO_BATCH; 836 } 837 #endif 838 839 *p = ++res; 840 put_cpu_var(last_ino); 841 return res; 842 } 843 EXPORT_SYMBOL(get_next_ino); 844 845 /** 846 * new_inode - obtain an inode 847 * @sb: superblock 848 * 849 * Allocates a new inode for given superblock. The default gfp_mask 850 * for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE. 851 * If HIGHMEM pages are unsuitable or it is known that pages allocated 852 * for the page cache are not reclaimable or migratable, 853 * mapping_set_gfp_mask() must be called with suitable flags on the 854 * newly created inode's mapping 855 * 856 */ 857 struct inode *new_inode(struct super_block *sb) 858 { 859 struct inode *inode; 860 861 spin_lock_prefetch(&inode_sb_list_lock); 862 863 inode = alloc_inode(sb); 864 if (inode) { 865 spin_lock(&inode->i_lock); 866 inode->i_state = 0; 867 spin_unlock(&inode->i_lock); 868 inode_sb_list_add(inode); 869 } 870 return inode; 871 } 872 EXPORT_SYMBOL(new_inode); 873 874 /** 875 * unlock_new_inode - clear the I_NEW state and wake up any waiters 876 * @inode: new inode to unlock 877 * 878 * Called when the inode is fully initialised to clear the new state of the 879 * inode and wake up anyone waiting for the inode to finish initialisation. 880 */ 881 void unlock_new_inode(struct inode *inode) 882 { 883 #ifdef CONFIG_DEBUG_LOCK_ALLOC 884 if (S_ISDIR(inode->i_mode)) { 885 struct file_system_type *type = inode->i_sb->s_type; 886 887 /* Set new key only if filesystem hasn't already changed it */ 888 if (!lockdep_match_class(&inode->i_mutex, 889 &type->i_mutex_key)) { 890 /* 891 * ensure nobody is actually holding i_mutex 892 */ 893 mutex_destroy(&inode->i_mutex); 894 mutex_init(&inode->i_mutex); 895 lockdep_set_class(&inode->i_mutex, 896 &type->i_mutex_dir_key); 897 } 898 } 899 #endif 900 spin_lock(&inode->i_lock); 901 WARN_ON(!(inode->i_state & I_NEW)); 902 inode->i_state &= ~I_NEW; 903 wake_up_bit(&inode->i_state, __I_NEW); 904 spin_unlock(&inode->i_lock); 905 } 906 EXPORT_SYMBOL(unlock_new_inode); 907 908 /** 909 * iget5_locked - obtain an inode from a mounted file system 910 * @sb: super block of file system 911 * @hashval: hash value (usually inode number) to get 912 * @test: callback used for comparisons between inodes 913 * @set: callback used to initialize a new struct inode 914 * @data: opaque data pointer to pass to @test and @set 915 * 916 * Search for the inode specified by @hashval and @data in the inode cache, 917 * and if present it is return it with an increased reference count. This is 918 * a generalized version of iget_locked() for file systems where the inode 919 * number is not sufficient for unique identification of an inode. 920 * 921 * If the inode is not in cache, allocate a new inode and return it locked, 922 * hashed, and with the I_NEW flag set. The file system gets to fill it in 923 * before unlocking it via unlock_new_inode(). 924 * 925 * Note both @test and @set are called with the inode_hash_lock held, so can't 926 * sleep. 927 */ 928 struct inode *iget5_locked(struct super_block *sb, unsigned long hashval, 929 int (*test)(struct inode *, void *), 930 int (*set)(struct inode *, void *), void *data) 931 { 932 struct hlist_head *head = inode_hashtable + hash(sb, hashval); 933 struct inode *inode; 934 935 spin_lock(&inode_hash_lock); 936 inode = find_inode(sb, head, test, data); 937 spin_unlock(&inode_hash_lock); 938 939 if (inode) { 940 wait_on_inode(inode); 941 return inode; 942 } 943 944 inode = alloc_inode(sb); 945 if (inode) { 946 struct inode *old; 947 948 spin_lock(&inode_hash_lock); 949 /* We released the lock, so.. */ 950 old = find_inode(sb, head, test, data); 951 if (!old) { 952 if (set(inode, data)) 953 goto set_failed; 954 955 spin_lock(&inode->i_lock); 956 inode->i_state = I_NEW; 957 hlist_add_head(&inode->i_hash, head); 958 spin_unlock(&inode->i_lock); 959 inode_sb_list_add(inode); 960 spin_unlock(&inode_hash_lock); 961 962 /* Return the locked inode with I_NEW set, the 963 * caller is responsible for filling in the contents 964 */ 965 return inode; 966 } 967 968 /* 969 * Uhhuh, somebody else created the same inode under 970 * us. Use the old inode instead of the one we just 971 * allocated. 972 */ 973 spin_unlock(&inode_hash_lock); 974 destroy_inode(inode); 975 inode = old; 976 wait_on_inode(inode); 977 } 978 return inode; 979 980 set_failed: 981 spin_unlock(&inode_hash_lock); 982 destroy_inode(inode); 983 return NULL; 984 } 985 EXPORT_SYMBOL(iget5_locked); 986 987 /** 988 * iget_locked - obtain an inode from a mounted file system 989 * @sb: super block of file system 990 * @ino: inode number to get 991 * 992 * Search for the inode specified by @ino in the inode cache and if present 993 * return it with an increased reference count. This is for file systems 994 * where the inode number is sufficient for unique identification of an inode. 995 * 996 * If the inode is not in cache, allocate a new inode and return it locked, 997 * hashed, and with the I_NEW flag set. The file system gets to fill it in 998 * before unlocking it via unlock_new_inode(). 999 */ 1000 struct inode *iget_locked(struct super_block *sb, unsigned long ino) 1001 { 1002 struct hlist_head *head = inode_hashtable + hash(sb, ino); 1003 struct inode *inode; 1004 1005 spin_lock(&inode_hash_lock); 1006 inode = find_inode_fast(sb, head, ino); 1007 spin_unlock(&inode_hash_lock); 1008 if (inode) { 1009 wait_on_inode(inode); 1010 return inode; 1011 } 1012 1013 inode = alloc_inode(sb); 1014 if (inode) { 1015 struct inode *old; 1016 1017 spin_lock(&inode_hash_lock); 1018 /* We released the lock, so.. */ 1019 old = find_inode_fast(sb, head, ino); 1020 if (!old) { 1021 inode->i_ino = ino; 1022 spin_lock(&inode->i_lock); 1023 inode->i_state = I_NEW; 1024 hlist_add_head(&inode->i_hash, head); 1025 spin_unlock(&inode->i_lock); 1026 inode_sb_list_add(inode); 1027 spin_unlock(&inode_hash_lock); 1028 1029 /* Return the locked inode with I_NEW set, the 1030 * caller is responsible for filling in the contents 1031 */ 1032 return inode; 1033 } 1034 1035 /* 1036 * Uhhuh, somebody else created the same inode under 1037 * us. Use the old inode instead of the one we just 1038 * allocated. 1039 */ 1040 spin_unlock(&inode_hash_lock); 1041 destroy_inode(inode); 1042 inode = old; 1043 wait_on_inode(inode); 1044 } 1045 return inode; 1046 } 1047 EXPORT_SYMBOL(iget_locked); 1048 1049 /* 1050 * search the inode cache for a matching inode number. 1051 * If we find one, then the inode number we are trying to 1052 * allocate is not unique and so we should not use it. 1053 * 1054 * Returns 1 if the inode number is unique, 0 if it is not. 1055 */ 1056 static int test_inode_iunique(struct super_block *sb, unsigned long ino) 1057 { 1058 struct hlist_head *b = inode_hashtable + hash(sb, ino); 1059 struct hlist_node *node; 1060 struct inode *inode; 1061 1062 spin_lock(&inode_hash_lock); 1063 hlist_for_each_entry(inode, node, b, i_hash) { 1064 if (inode->i_ino == ino && inode->i_sb == sb) { 1065 spin_unlock(&inode_hash_lock); 1066 return 0; 1067 } 1068 } 1069 spin_unlock(&inode_hash_lock); 1070 1071 return 1; 1072 } 1073 1074 /** 1075 * iunique - get a unique inode number 1076 * @sb: superblock 1077 * @max_reserved: highest reserved inode number 1078 * 1079 * Obtain an inode number that is unique on the system for a given 1080 * superblock. This is used by file systems that have no natural 1081 * permanent inode numbering system. An inode number is returned that 1082 * is higher than the reserved limit but unique. 1083 * 1084 * BUGS: 1085 * With a large number of inodes live on the file system this function 1086 * currently becomes quite slow. 1087 */ 1088 ino_t iunique(struct super_block *sb, ino_t max_reserved) 1089 { 1090 /* 1091 * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW 1092 * error if st_ino won't fit in target struct field. Use 32bit counter 1093 * here to attempt to avoid that. 1094 */ 1095 static DEFINE_SPINLOCK(iunique_lock); 1096 static unsigned int counter; 1097 ino_t res; 1098 1099 spin_lock(&iunique_lock); 1100 do { 1101 if (counter <= max_reserved) 1102 counter = max_reserved + 1; 1103 res = counter++; 1104 } while (!test_inode_iunique(sb, res)); 1105 spin_unlock(&iunique_lock); 1106 1107 return res; 1108 } 1109 EXPORT_SYMBOL(iunique); 1110 1111 struct inode *igrab(struct inode *inode) 1112 { 1113 spin_lock(&inode->i_lock); 1114 if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) { 1115 __iget(inode); 1116 spin_unlock(&inode->i_lock); 1117 } else { 1118 spin_unlock(&inode->i_lock); 1119 /* 1120 * Handle the case where s_op->clear_inode is not been 1121 * called yet, and somebody is calling igrab 1122 * while the inode is getting freed. 1123 */ 1124 inode = NULL; 1125 } 1126 return inode; 1127 } 1128 EXPORT_SYMBOL(igrab); 1129 1130 /** 1131 * ilookup5_nowait - search for an inode in the inode cache 1132 * @sb: super block of file system to search 1133 * @hashval: hash value (usually inode number) to search for 1134 * @test: callback used for comparisons between inodes 1135 * @data: opaque data pointer to pass to @test 1136 * 1137 * Search for the inode specified by @hashval and @data in the inode cache. 1138 * If the inode is in the cache, the inode is returned with an incremented 1139 * reference count. 1140 * 1141 * Note: I_NEW is not waited upon so you have to be very careful what you do 1142 * with the returned inode. You probably should be using ilookup5() instead. 1143 * 1144 * Note2: @test is called with the inode_hash_lock held, so can't sleep. 1145 */ 1146 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval, 1147 int (*test)(struct inode *, void *), void *data) 1148 { 1149 struct hlist_head *head = inode_hashtable + hash(sb, hashval); 1150 struct inode *inode; 1151 1152 spin_lock(&inode_hash_lock); 1153 inode = find_inode(sb, head, test, data); 1154 spin_unlock(&inode_hash_lock); 1155 1156 return inode; 1157 } 1158 EXPORT_SYMBOL(ilookup5_nowait); 1159 1160 /** 1161 * ilookup5 - search for an inode in the inode cache 1162 * @sb: super block of file system to search 1163 * @hashval: hash value (usually inode number) to search for 1164 * @test: callback used for comparisons between inodes 1165 * @data: opaque data pointer to pass to @test 1166 * 1167 * Search for the inode specified by @hashval and @data in the inode cache, 1168 * and if the inode is in the cache, return the inode with an incremented 1169 * reference count. Waits on I_NEW before returning the inode. 1170 * returned with an incremented reference count. 1171 * 1172 * This is a generalized version of ilookup() for file systems where the 1173 * inode number is not sufficient for unique identification of an inode. 1174 * 1175 * Note: @test is called with the inode_hash_lock held, so can't sleep. 1176 */ 1177 struct inode *ilookup5(struct super_block *sb, unsigned long hashval, 1178 int (*test)(struct inode *, void *), void *data) 1179 { 1180 struct inode *inode = ilookup5_nowait(sb, hashval, test, data); 1181 1182 if (inode) 1183 wait_on_inode(inode); 1184 return inode; 1185 } 1186 EXPORT_SYMBOL(ilookup5); 1187 1188 /** 1189 * ilookup - search for an inode in the inode cache 1190 * @sb: super block of file system to search 1191 * @ino: inode number to search for 1192 * 1193 * Search for the inode @ino in the inode cache, and if the inode is in the 1194 * cache, the inode is returned with an incremented reference count. 1195 */ 1196 struct inode *ilookup(struct super_block *sb, unsigned long ino) 1197 { 1198 struct hlist_head *head = inode_hashtable + hash(sb, ino); 1199 struct inode *inode; 1200 1201 spin_lock(&inode_hash_lock); 1202 inode = find_inode_fast(sb, head, ino); 1203 spin_unlock(&inode_hash_lock); 1204 1205 if (inode) 1206 wait_on_inode(inode); 1207 return inode; 1208 } 1209 EXPORT_SYMBOL(ilookup); 1210 1211 int insert_inode_locked(struct inode *inode) 1212 { 1213 struct super_block *sb = inode->i_sb; 1214 ino_t ino = inode->i_ino; 1215 struct hlist_head *head = inode_hashtable + hash(sb, ino); 1216 1217 while (1) { 1218 struct hlist_node *node; 1219 struct inode *old = NULL; 1220 spin_lock(&inode_hash_lock); 1221 hlist_for_each_entry(old, node, head, i_hash) { 1222 if (old->i_ino != ino) 1223 continue; 1224 if (old->i_sb != sb) 1225 continue; 1226 spin_lock(&old->i_lock); 1227 if (old->i_state & (I_FREEING|I_WILL_FREE)) { 1228 spin_unlock(&old->i_lock); 1229 continue; 1230 } 1231 break; 1232 } 1233 if (likely(!node)) { 1234 spin_lock(&inode->i_lock); 1235 inode->i_state |= I_NEW; 1236 hlist_add_head(&inode->i_hash, head); 1237 spin_unlock(&inode->i_lock); 1238 spin_unlock(&inode_hash_lock); 1239 return 0; 1240 } 1241 __iget(old); 1242 spin_unlock(&old->i_lock); 1243 spin_unlock(&inode_hash_lock); 1244 wait_on_inode(old); 1245 if (unlikely(!inode_unhashed(old))) { 1246 iput(old); 1247 return -EBUSY; 1248 } 1249 iput(old); 1250 } 1251 } 1252 EXPORT_SYMBOL(insert_inode_locked); 1253 1254 int insert_inode_locked4(struct inode *inode, unsigned long hashval, 1255 int (*test)(struct inode *, void *), void *data) 1256 { 1257 struct super_block *sb = inode->i_sb; 1258 struct hlist_head *head = inode_hashtable + hash(sb, hashval); 1259 1260 while (1) { 1261 struct hlist_node *node; 1262 struct inode *old = NULL; 1263 1264 spin_lock(&inode_hash_lock); 1265 hlist_for_each_entry(old, node, head, i_hash) { 1266 if (old->i_sb != sb) 1267 continue; 1268 if (!test(old, data)) 1269 continue; 1270 spin_lock(&old->i_lock); 1271 if (old->i_state & (I_FREEING|I_WILL_FREE)) { 1272 spin_unlock(&old->i_lock); 1273 continue; 1274 } 1275 break; 1276 } 1277 if (likely(!node)) { 1278 spin_lock(&inode->i_lock); 1279 inode->i_state |= I_NEW; 1280 hlist_add_head(&inode->i_hash, head); 1281 spin_unlock(&inode->i_lock); 1282 spin_unlock(&inode_hash_lock); 1283 return 0; 1284 } 1285 __iget(old); 1286 spin_unlock(&old->i_lock); 1287 spin_unlock(&inode_hash_lock); 1288 wait_on_inode(old); 1289 if (unlikely(!inode_unhashed(old))) { 1290 iput(old); 1291 return -EBUSY; 1292 } 1293 iput(old); 1294 } 1295 } 1296 EXPORT_SYMBOL(insert_inode_locked4); 1297 1298 1299 int generic_delete_inode(struct inode *inode) 1300 { 1301 return 1; 1302 } 1303 EXPORT_SYMBOL(generic_delete_inode); 1304 1305 /* 1306 * Normal UNIX filesystem behaviour: delete the 1307 * inode when the usage count drops to zero, and 1308 * i_nlink is zero. 1309 */ 1310 int generic_drop_inode(struct inode *inode) 1311 { 1312 return !inode->i_nlink || inode_unhashed(inode); 1313 } 1314 EXPORT_SYMBOL_GPL(generic_drop_inode); 1315 1316 /* 1317 * Called when we're dropping the last reference 1318 * to an inode. 1319 * 1320 * Call the FS "drop_inode()" function, defaulting to 1321 * the legacy UNIX filesystem behaviour. If it tells 1322 * us to evict inode, do so. Otherwise, retain inode 1323 * in cache if fs is alive, sync and evict if fs is 1324 * shutting down. 1325 */ 1326 static void iput_final(struct inode *inode) 1327 { 1328 struct super_block *sb = inode->i_sb; 1329 const struct super_operations *op = inode->i_sb->s_op; 1330 int drop; 1331 1332 WARN_ON(inode->i_state & I_NEW); 1333 1334 if (op && op->drop_inode) 1335 drop = op->drop_inode(inode); 1336 else 1337 drop = generic_drop_inode(inode); 1338 1339 if (!drop && (sb->s_flags & MS_ACTIVE)) { 1340 inode->i_state |= I_REFERENCED; 1341 if (!(inode->i_state & (I_DIRTY|I_SYNC))) 1342 inode_lru_list_add(inode); 1343 spin_unlock(&inode->i_lock); 1344 return; 1345 } 1346 1347 if (!drop) { 1348 inode->i_state |= I_WILL_FREE; 1349 spin_unlock(&inode->i_lock); 1350 write_inode_now(inode, 1); 1351 spin_lock(&inode->i_lock); 1352 WARN_ON(inode->i_state & I_NEW); 1353 inode->i_state &= ~I_WILL_FREE; 1354 } 1355 1356 inode->i_state |= I_FREEING; 1357 inode_lru_list_del(inode); 1358 spin_unlock(&inode->i_lock); 1359 1360 evict(inode); 1361 } 1362 1363 /** 1364 * iput - put an inode 1365 * @inode: inode to put 1366 * 1367 * Puts an inode, dropping its usage count. If the inode use count hits 1368 * zero, the inode is then freed and may also be destroyed. 1369 * 1370 * Consequently, iput() can sleep. 1371 */ 1372 void iput(struct inode *inode) 1373 { 1374 if (inode) { 1375 BUG_ON(inode->i_state & I_CLEAR); 1376 1377 if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) 1378 iput_final(inode); 1379 } 1380 } 1381 EXPORT_SYMBOL(iput); 1382 1383 /** 1384 * bmap - find a block number in a file 1385 * @inode: inode of file 1386 * @block: block to find 1387 * 1388 * Returns the block number on the device holding the inode that 1389 * is the disk block number for the block of the file requested. 1390 * That is, asked for block 4 of inode 1 the function will return the 1391 * disk block relative to the disk start that holds that block of the 1392 * file. 1393 */ 1394 sector_t bmap(struct inode *inode, sector_t block) 1395 { 1396 sector_t res = 0; 1397 if (inode->i_mapping->a_ops->bmap) 1398 res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block); 1399 return res; 1400 } 1401 EXPORT_SYMBOL(bmap); 1402 1403 /* 1404 * With relative atime, only update atime if the previous atime is 1405 * earlier than either the ctime or mtime or if at least a day has 1406 * passed since the last atime update. 1407 */ 1408 static int relatime_need_update(struct vfsmount *mnt, struct inode *inode, 1409 struct timespec now) 1410 { 1411 1412 if (!(mnt->mnt_flags & MNT_RELATIME)) 1413 return 1; 1414 /* 1415 * Is mtime younger than atime? If yes, update atime: 1416 */ 1417 if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0) 1418 return 1; 1419 /* 1420 * Is ctime younger than atime? If yes, update atime: 1421 */ 1422 if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0) 1423 return 1; 1424 1425 /* 1426 * Is the previous atime value older than a day? If yes, 1427 * update atime: 1428 */ 1429 if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60) 1430 return 1; 1431 /* 1432 * Good, we can skip the atime update: 1433 */ 1434 return 0; 1435 } 1436 1437 /** 1438 * touch_atime - update the access time 1439 * @mnt: mount the inode is accessed on 1440 * @dentry: dentry accessed 1441 * 1442 * Update the accessed time on an inode and mark it for writeback. 1443 * This function automatically handles read only file systems and media, 1444 * as well as the "noatime" flag and inode specific "noatime" markers. 1445 */ 1446 void touch_atime(struct vfsmount *mnt, struct dentry *dentry) 1447 { 1448 struct inode *inode = dentry->d_inode; 1449 struct timespec now; 1450 1451 if (inode->i_flags & S_NOATIME) 1452 return; 1453 if (IS_NOATIME(inode)) 1454 return; 1455 if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode)) 1456 return; 1457 1458 if (mnt->mnt_flags & MNT_NOATIME) 1459 return; 1460 if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)) 1461 return; 1462 1463 now = current_fs_time(inode->i_sb); 1464 1465 if (!relatime_need_update(mnt, inode, now)) 1466 return; 1467 1468 if (timespec_equal(&inode->i_atime, &now)) 1469 return; 1470 1471 if (mnt_want_write(mnt)) 1472 return; 1473 1474 inode->i_atime = now; 1475 mark_inode_dirty_sync(inode); 1476 mnt_drop_write(mnt); 1477 } 1478 EXPORT_SYMBOL(touch_atime); 1479 1480 /** 1481 * file_update_time - update mtime and ctime time 1482 * @file: file accessed 1483 * 1484 * Update the mtime and ctime members of an inode and mark the inode 1485 * for writeback. Note that this function is meant exclusively for 1486 * usage in the file write path of filesystems, and filesystems may 1487 * choose to explicitly ignore update via this function with the 1488 * S_NOCMTIME inode flag, e.g. for network filesystem where these 1489 * timestamps are handled by the server. 1490 */ 1491 1492 void file_update_time(struct file *file) 1493 { 1494 struct inode *inode = file->f_path.dentry->d_inode; 1495 struct timespec now; 1496 enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0; 1497 1498 /* First try to exhaust all avenues to not sync */ 1499 if (IS_NOCMTIME(inode)) 1500 return; 1501 1502 now = current_fs_time(inode->i_sb); 1503 if (!timespec_equal(&inode->i_mtime, &now)) 1504 sync_it = S_MTIME; 1505 1506 if (!timespec_equal(&inode->i_ctime, &now)) 1507 sync_it |= S_CTIME; 1508 1509 if (IS_I_VERSION(inode)) 1510 sync_it |= S_VERSION; 1511 1512 if (!sync_it) 1513 return; 1514 1515 /* Finally allowed to write? Takes lock. */ 1516 if (mnt_want_write_file(file)) 1517 return; 1518 1519 /* Only change inode inside the lock region */ 1520 if (sync_it & S_VERSION) 1521 inode_inc_iversion(inode); 1522 if (sync_it & S_CTIME) 1523 inode->i_ctime = now; 1524 if (sync_it & S_MTIME) 1525 inode->i_mtime = now; 1526 mark_inode_dirty_sync(inode); 1527 mnt_drop_write(file->f_path.mnt); 1528 } 1529 EXPORT_SYMBOL(file_update_time); 1530 1531 int inode_needs_sync(struct inode *inode) 1532 { 1533 if (IS_SYNC(inode)) 1534 return 1; 1535 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) 1536 return 1; 1537 return 0; 1538 } 1539 EXPORT_SYMBOL(inode_needs_sync); 1540 1541 int inode_wait(void *word) 1542 { 1543 schedule(); 1544 return 0; 1545 } 1546 EXPORT_SYMBOL(inode_wait); 1547 1548 /* 1549 * If we try to find an inode in the inode hash while it is being 1550 * deleted, we have to wait until the filesystem completes its 1551 * deletion before reporting that it isn't found. This function waits 1552 * until the deletion _might_ have completed. Callers are responsible 1553 * to recheck inode state. 1554 * 1555 * It doesn't matter if I_NEW is not set initially, a call to 1556 * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list 1557 * will DTRT. 1558 */ 1559 static void __wait_on_freeing_inode(struct inode *inode) 1560 { 1561 wait_queue_head_t *wq; 1562 DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW); 1563 wq = bit_waitqueue(&inode->i_state, __I_NEW); 1564 prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE); 1565 spin_unlock(&inode->i_lock); 1566 spin_unlock(&inode_hash_lock); 1567 schedule(); 1568 finish_wait(wq, &wait.wait); 1569 spin_lock(&inode_hash_lock); 1570 } 1571 1572 static __initdata unsigned long ihash_entries; 1573 static int __init set_ihash_entries(char *str) 1574 { 1575 if (!str) 1576 return 0; 1577 ihash_entries = simple_strtoul(str, &str, 0); 1578 return 1; 1579 } 1580 __setup("ihash_entries=", set_ihash_entries); 1581 1582 /* 1583 * Initialize the waitqueues and inode hash table. 1584 */ 1585 void __init inode_init_early(void) 1586 { 1587 int loop; 1588 1589 /* If hashes are distributed across NUMA nodes, defer 1590 * hash allocation until vmalloc space is available. 1591 */ 1592 if (hashdist) 1593 return; 1594 1595 inode_hashtable = 1596 alloc_large_system_hash("Inode-cache", 1597 sizeof(struct hlist_head), 1598 ihash_entries, 1599 14, 1600 HASH_EARLY, 1601 &i_hash_shift, 1602 &i_hash_mask, 1603 0); 1604 1605 for (loop = 0; loop < (1 << i_hash_shift); loop++) 1606 INIT_HLIST_HEAD(&inode_hashtable[loop]); 1607 } 1608 1609 void __init inode_init(void) 1610 { 1611 int loop; 1612 1613 /* inode slab cache */ 1614 inode_cachep = kmem_cache_create("inode_cache", 1615 sizeof(struct inode), 1616 0, 1617 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| 1618 SLAB_MEM_SPREAD), 1619 init_once); 1620 register_shrinker(&icache_shrinker); 1621 1622 /* Hash may have been set up in inode_init_early */ 1623 if (!hashdist) 1624 return; 1625 1626 inode_hashtable = 1627 alloc_large_system_hash("Inode-cache", 1628 sizeof(struct hlist_head), 1629 ihash_entries, 1630 14, 1631 0, 1632 &i_hash_shift, 1633 &i_hash_mask, 1634 0); 1635 1636 for (loop = 0; loop < (1 << i_hash_shift); loop++) 1637 INIT_HLIST_HEAD(&inode_hashtable[loop]); 1638 } 1639 1640 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev) 1641 { 1642 inode->i_mode = mode; 1643 if (S_ISCHR(mode)) { 1644 inode->i_fop = &def_chr_fops; 1645 inode->i_rdev = rdev; 1646 } else if (S_ISBLK(mode)) { 1647 inode->i_fop = &def_blk_fops; 1648 inode->i_rdev = rdev; 1649 } else if (S_ISFIFO(mode)) 1650 inode->i_fop = &def_fifo_fops; 1651 else if (S_ISSOCK(mode)) 1652 inode->i_fop = &bad_sock_fops; 1653 else 1654 printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for" 1655 " inode %s:%lu\n", mode, inode->i_sb->s_id, 1656 inode->i_ino); 1657 } 1658 EXPORT_SYMBOL(init_special_inode); 1659 1660 /** 1661 * inode_init_owner - Init uid,gid,mode for new inode according to posix standards 1662 * @inode: New inode 1663 * @dir: Directory inode 1664 * @mode: mode of the new inode 1665 */ 1666 void inode_init_owner(struct inode *inode, const struct inode *dir, 1667 mode_t mode) 1668 { 1669 inode->i_uid = current_fsuid(); 1670 if (dir && dir->i_mode & S_ISGID) { 1671 inode->i_gid = dir->i_gid; 1672 if (S_ISDIR(mode)) 1673 mode |= S_ISGID; 1674 } else 1675 inode->i_gid = current_fsgid(); 1676 inode->i_mode = mode; 1677 } 1678 EXPORT_SYMBOL(inode_init_owner); 1679 1680 /** 1681 * inode_owner_or_capable - check current task permissions to inode 1682 * @inode: inode being checked 1683 * 1684 * Return true if current either has CAP_FOWNER to the inode, or 1685 * owns the file. 1686 */ 1687 bool inode_owner_or_capable(const struct inode *inode) 1688 { 1689 struct user_namespace *ns = inode_userns(inode); 1690 1691 if (current_user_ns() == ns && current_fsuid() == inode->i_uid) 1692 return true; 1693 if (ns_capable(ns, CAP_FOWNER)) 1694 return true; 1695 return false; 1696 } 1697 EXPORT_SYMBOL(inode_owner_or_capable); 1698