root/fs/inode.c

/* [previous][next][first][last][top][bottom][index][help] [+1 fs/inode.c] */

DEFINITIONS

This source file includes following definitions.
  1. get_nr_inodes
  2. get_nr_inodes_unused
  3. get_nr_dirty_inodes
  4. proc_nr_inodes
  5. no_open
  6. inode_init_always
  7. alloc_inode
  8. free_inode_nonrcu
  9. __destroy_inode
  10. i_callback
  11. destroy_inode
  12. drop_nlink
  13. clear_nlink
  14. set_nlink
  15. inc_nlink
  16. address_space_init_once
  17. inode_init_once
  18. init_once
  19. __iget
  20. ihold
  21. inode_lru_list_add
  22. inode_add_lru
  23. inode_lru_list_del
  24. inode_sb_list_add
  25. inode_sb_list_del
  26. hash
  27. __insert_inode_hash
  28. __remove_inode_hash
  29. clear_inode
  30. evict
  31. dispose_list
  32. evict_inodes
  33. invalidate_inodes
  34. inode_lru_isolate
  35. prune_icache_sb
  36. find_inode
  37. find_inode_fast
  38. get_next_ino
  39. new_inode_pseudo
  40. new_inode
  41. lockdep_annotate_inode_mutex_key
  42. unlock_new_inode
  43. lock_two_nondirectories
  44. unlock_two_nondirectories
  45. iget5_locked
  46. iget_locked
  47. test_inode_iunique
  48. iunique
  49. igrab
  50. ilookup5_nowait
  51. ilookup5
  52. ilookup
  53. find_inode_nowait
  54. insert_inode_locked
  55. insert_inode_locked4
  56. generic_delete_inode
  57. iput_final
  58. iput
  59. bmap
  60. relatime_need_update
  61. generic_update_time
  62. update_time
  63. atime_needs_update
  64. touch_atime
  65. should_remove_suid
  66. dentry_needs_remove_privs
  67. __remove_privs
  68. file_remove_privs
  69. file_update_time
  70. inode_needs_sync
  71. __wait_on_freeing_inode
  72. set_ihash_entries
  73. inode_init_early
  74. inode_init
  75. init_special_inode
  76. inode_init_owner
  77. inode_owner_or_capable
  78. __inode_dio_wait
  79. inode_dio_wait
  80. inode_set_flags

   1 /*
   2  * (C) 1997 Linus Torvalds
   3  * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation)
   4  */
   5 #include <linux/export.h>
   6 #include <linux/fs.h>
   7 #include <linux/mm.h>
   8 #include <linux/backing-dev.h>
   9 #include <linux/hash.h>
  10 #include <linux/swap.h>
  11 #include <linux/security.h>
  12 #include <linux/cdev.h>
  13 #include <linux/bootmem.h>
  14 #include <linux/fsnotify.h>
  15 #include <linux/mount.h>
  16 #include <linux/posix_acl.h>
  17 #include <linux/prefetch.h>
  18 #include <linux/buffer_head.h> /* for inode_has_buffers */
  19 #include <linux/ratelimit.h>
  20 #include <linux/list_lru.h>
  21 #include <trace/events/writeback.h>
  22 #include "internal.h"
  23 
  24 /*
  25  * Inode locking rules:
  26  *
  27  * inode->i_lock protects:
  28  *   inode->i_state, inode->i_hash, __iget()
  29  * Inode LRU list locks protect:
  30  *   inode->i_sb->s_inode_lru, inode->i_lru
  31  * inode->i_sb->s_inode_list_lock protects:
  32  *   inode->i_sb->s_inodes, inode->i_sb_list
  33  * bdi->wb.list_lock protects:
  34  *   bdi->wb.b_{dirty,io,more_io,dirty_time}, inode->i_io_list
  35  * inode_hash_lock protects:
  36  *   inode_hashtable, inode->i_hash
  37  *
  38  * Lock ordering:
  39  *
  40  * inode->i_sb->s_inode_list_lock
  41  *   inode->i_lock
  42  *     Inode LRU list locks
  43  *
  44  * bdi->wb.list_lock
  45  *   inode->i_lock
  46  *
  47  * inode_hash_lock
  48  *   inode->i_sb->s_inode_list_lock
  49  *   inode->i_lock
  50  *
  51  * iunique_lock
  52  *   inode_hash_lock
  53  */
  54 
  55 static unsigned int i_hash_mask __read_mostly;
  56 static unsigned int i_hash_shift __read_mostly;
  57 static struct hlist_head *inode_hashtable __read_mostly;
  58 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock);
  59 
  60 /*
  61  * Empty aops. Can be used for the cases where the user does not
  62  * define any of the address_space operations.
  63  */
  64 const struct address_space_operations empty_aops = {
  65 };
  66 EXPORT_SYMBOL(empty_aops);
  67 
  68 /*
  69  * Statistics gathering..
  70  */
  71 struct inodes_stat_t inodes_stat;
  72 
  73 static DEFINE_PER_CPU(unsigned long, nr_inodes);
  74 static DEFINE_PER_CPU(unsigned long, nr_unused);
  75 
  76 static struct kmem_cache *inode_cachep __read_mostly;
  77 
  78 static long get_nr_inodes(void)
     /* [previous][next][first][last][top][bottom][index][help] [+78 fs/inode.c] */
  79 {
  80         int i;
  81         long sum = 0;
  82         for_each_possible_cpu(i)
  83                 sum += per_cpu(nr_inodes, i);
  84         return sum < 0 ? 0 : sum;
  85 }
  86 
  87 static inline long get_nr_inodes_unused(void)
     /* [previous][next][first][last][top][bottom][index][help] [+87 fs/inode.c] */
  88 {
  89         int i;
  90         long sum = 0;
  91         for_each_possible_cpu(i)
  92                 sum += per_cpu(nr_unused, i);
  93         return sum < 0 ? 0 : sum;
  94 }
  95 
  96 long get_nr_dirty_inodes(void)
     /* [previous][next][first][last][top][bottom][index][help] [+96 fs/inode.c] */
  97 {
  98         /* not actually dirty inodes, but a wild approximation */
  99         long nr_dirty = get_nr_inodes() - get_nr_inodes_unused();
 100         return nr_dirty > 0 ? nr_dirty : 0;
 101 }
 102 
 103 /*
 104  * Handle nr_inode sysctl
 105  */
 106 #ifdef CONFIG_SYSCTL
 107 int proc_nr_inodes(struct ctl_table *table, int write,
     /* [previous][next][first][last][top][bottom][index][help] [+107 fs/inode.c] */
 108                    void __user *buffer, size_t *lenp, loff_t *ppos)
 109 {
 110         inodes_stat.nr_inodes = get_nr_inodes();
 111         inodes_stat.nr_unused = get_nr_inodes_unused();
 112         return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
 113 }
 114 #endif
 115 
 116 static int no_open(struct inode *inode, struct file *file)
     /* [previous][next][first][last][top][bottom][index][help] [+116 fs/inode.c] */
 117 {
 118         return -ENXIO;
 119 }
 120 
 121 /**
 122  * inode_init_always - perform inode structure intialisation
 123  * @sb: superblock inode belongs to
 124  * @inode: inode to initialise
 125  *
 126  * These are initializations that need to be done on every inode
 127  * allocation as the fields are not initialised by slab allocation.
 128  */
 129 int inode_init_always(struct super_block *sb, struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+129 fs/inode.c] */
 130 {
 131         static const struct inode_operations empty_iops;
 132         static const struct file_operations no_open_fops = {.open = no_open};
 133         struct address_space *const mapping = &inode->i_data;
 134 
 135         inode->i_sb = sb;
 136         inode->i_blkbits = sb->s_blocksize_bits;
 137         inode->i_flags = 0;
 138         atomic_set(&inode->i_count, 1);
 139         inode->i_op = &empty_iops;
 140         inode->i_fop = &no_open_fops;
 141         inode->__i_nlink = 1;
 142         inode->i_opflags = 0;
 143         i_uid_write(inode, 0);
 144         i_gid_write(inode, 0);
 145         atomic_set(&inode->i_writecount, 0);
 146         inode->i_size = 0;
 147         inode->i_blocks = 0;
 148         inode->i_bytes = 0;
 149         inode->i_generation = 0;
 150         inode->i_pipe = NULL;
 151         inode->i_bdev = NULL;
 152         inode->i_cdev = NULL;
 153         inode->i_link = NULL;
 154         inode->i_rdev = 0;
 155         inode->dirtied_when = 0;
 156 
 157         if (security_inode_alloc(inode))
 158                 goto out;
 159         spin_lock_init(&inode->i_lock);
 160         lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);
 161 
 162         mutex_init(&inode->i_mutex);
 163         lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);
 164 
 165         atomic_set(&inode->i_dio_count, 0);
 166 
 167         mapping->a_ops = &empty_aops;
 168         mapping->host = inode;
 169         mapping->flags = 0;
 170         atomic_set(&mapping->i_mmap_writable, 0);
 171         mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
 172         mapping->private_data = NULL;
 173         mapping->writeback_index = 0;
 174         inode->i_private = NULL;
 175         inode->i_mapping = mapping;
 176         INIT_HLIST_HEAD(&inode->i_dentry);      /* buggered by rcu freeing */
 177 #ifdef CONFIG_FS_POSIX_ACL
 178         inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
 179 #endif
 180 
 181 #ifdef CONFIG_FSNOTIFY
 182         inode->i_fsnotify_mask = 0;
 183 #endif
 184         inode->i_flctx = NULL;
 185         this_cpu_inc(nr_inodes);
 186 
 187         return 0;
 188 out:
 189         return -ENOMEM;
 190 }
 191 EXPORT_SYMBOL(inode_init_always);
 192 
 193 static struct inode *alloc_inode(struct super_block *sb)
     /* [previous][next][first][last][top][bottom][index][help] [+193 fs/inode.c] */
 194 {
 195         struct inode *inode;
 196 
 197         if (sb->s_op->alloc_inode)
 198                 inode = sb->s_op->alloc_inode(sb);
 199         else
 200                 inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);
 201 
 202         if (!inode)
 203                 return NULL;
 204 
 205         if (unlikely(inode_init_always(sb, inode))) {
 206                 if (inode->i_sb->s_op->destroy_inode)
 207                         inode->i_sb->s_op->destroy_inode(inode);
 208                 else
 209                         kmem_cache_free(inode_cachep, inode);
 210                 return NULL;
 211         }
 212 
 213         return inode;
 214 }
 215 
 216 void free_inode_nonrcu(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+216 fs/inode.c] */
 217 {
 218         kmem_cache_free(inode_cachep, inode);
 219 }
 220 EXPORT_SYMBOL(free_inode_nonrcu);
 221 
 222 void __destroy_inode(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+222 fs/inode.c] */
 223 {
 224         BUG_ON(inode_has_buffers(inode));
 225         inode_detach_wb(inode);
 226         security_inode_free(inode);
 227         fsnotify_inode_delete(inode);
 228         locks_free_lock_context(inode->i_flctx);
 229         if (!inode->i_nlink) {
 230                 WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0);
 231                 atomic_long_dec(&inode->i_sb->s_remove_count);
 232         }
 233 
 234 #ifdef CONFIG_FS_POSIX_ACL
 235         if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
 236                 posix_acl_release(inode->i_acl);
 237         if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
 238                 posix_acl_release(inode->i_default_acl);
 239 #endif
 240         this_cpu_dec(nr_inodes);
 241 }
 242 EXPORT_SYMBOL(__destroy_inode);
 243 
 244 static void i_callback(struct rcu_head *head)
     /* [previous][next][first][last][top][bottom][index][help] [+244 fs/inode.c] */
 245 {
 246         struct inode *inode = container_of(head, struct inode, i_rcu);
 247         kmem_cache_free(inode_cachep, inode);
 248 }
 249 
 250 static void destroy_inode(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+250 fs/inode.c] */
 251 {
 252         BUG_ON(!list_empty(&inode->i_lru));
 253         __destroy_inode(inode);
 254         if (inode->i_sb->s_op->destroy_inode)
 255                 inode->i_sb->s_op->destroy_inode(inode);
 256         else
 257                 call_rcu(&inode->i_rcu, i_callback);
 258 }
 259 
 260 /**
 261  * drop_nlink - directly drop an inode's link count
 262  * @inode: inode
 263  *
 264  * This is a low-level filesystem helper to replace any
 265  * direct filesystem manipulation of i_nlink.  In cases
 266  * where we are attempting to track writes to the
 267  * filesystem, a decrement to zero means an imminent
 268  * write when the file is truncated and actually unlinked
 269  * on the filesystem.
 270  */
 271 void drop_nlink(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+271 fs/inode.c] */
 272 {
 273         WARN_ON(inode->i_nlink == 0);
 274         inode->__i_nlink--;
 275         if (!inode->i_nlink)
 276                 atomic_long_inc(&inode->i_sb->s_remove_count);
 277 }
 278 EXPORT_SYMBOL(drop_nlink);
 279 
 280 /**
 281  * clear_nlink - directly zero an inode's link count
 282  * @inode: inode
 283  *
 284  * This is a low-level filesystem helper to replace any
 285  * direct filesystem manipulation of i_nlink.  See
 286  * drop_nlink() for why we care about i_nlink hitting zero.
 287  */
 288 void clear_nlink(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+288 fs/inode.c] */
 289 {
 290         if (inode->i_nlink) {
 291                 inode->__i_nlink = 0;
 292                 atomic_long_inc(&inode->i_sb->s_remove_count);
 293         }
 294 }
 295 EXPORT_SYMBOL(clear_nlink);
 296 
 297 /**
 298  * set_nlink - directly set an inode's link count
 299  * @inode: inode
 300  * @nlink: new nlink (should be non-zero)
 301  *
 302  * This is a low-level filesystem helper to replace any
 303  * direct filesystem manipulation of i_nlink.
 304  */
 305 void set_nlink(struct inode *inode, unsigned int nlink)
     /* [previous][next][first][last][top][bottom][index][help] [+305 fs/inode.c] */
 306 {
 307         if (!nlink) {
 308                 clear_nlink(inode);
 309         } else {
 310                 /* Yes, some filesystems do change nlink from zero to one */
 311                 if (inode->i_nlink == 0)
 312                         atomic_long_dec(&inode->i_sb->s_remove_count);
 313 
 314                 inode->__i_nlink = nlink;
 315         }
 316 }
 317 EXPORT_SYMBOL(set_nlink);
 318 
 319 /**
 320  * inc_nlink - directly increment an inode's link count
 321  * @inode: inode
 322  *
 323  * This is a low-level filesystem helper to replace any
 324  * direct filesystem manipulation of i_nlink.  Currently,
 325  * it is only here for parity with dec_nlink().
 326  */
 327 void inc_nlink(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+327 fs/inode.c] */
 328 {
 329         if (unlikely(inode->i_nlink == 0)) {
 330                 WARN_ON(!(inode->i_state & I_LINKABLE));
 331                 atomic_long_dec(&inode->i_sb->s_remove_count);
 332         }
 333 
 334         inode->__i_nlink++;
 335 }
 336 EXPORT_SYMBOL(inc_nlink);
 337 
 338 void address_space_init_once(struct address_space *mapping)
     /* [previous][next][first][last][top][bottom][index][help] [+338 fs/inode.c] */
 339 {
 340         memset(mapping, 0, sizeof(*mapping));
 341         INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
 342         spin_lock_init(&mapping->tree_lock);
 343         init_rwsem(&mapping->i_mmap_rwsem);
 344         INIT_LIST_HEAD(&mapping->private_list);
 345         spin_lock_init(&mapping->private_lock);
 346         mapping->i_mmap = RB_ROOT;
 347 }
 348 EXPORT_SYMBOL(address_space_init_once);
 349 
 350 /*
 351  * These are initializations that only need to be done
 352  * once, because the fields are idempotent across use
 353  * of the inode, so let the slab aware of that.
 354  */
 355 void inode_init_once(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+355 fs/inode.c] */
 356 {
 357         memset(inode, 0, sizeof(*inode));
 358         INIT_HLIST_NODE(&inode->i_hash);
 359         INIT_LIST_HEAD(&inode->i_devices);
 360         INIT_LIST_HEAD(&inode->i_io_list);
 361         INIT_LIST_HEAD(&inode->i_lru);
 362         address_space_init_once(&inode->i_data);
 363         i_size_ordered_init(inode);
 364 #ifdef CONFIG_FSNOTIFY
 365         INIT_HLIST_HEAD(&inode->i_fsnotify_marks);
 366 #endif
 367 }
 368 EXPORT_SYMBOL(inode_init_once);
 369 
 370 static void init_once(void *foo)
     /* [previous][next][first][last][top][bottom][index][help] [+370 fs/inode.c] */
 371 {
 372         struct inode *inode = (struct inode *) foo;
 373 
 374         inode_init_once(inode);
 375 }
 376 
 377 /*
 378  * inode->i_lock must be held
 379  */
 380 void __iget(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+380 fs/inode.c] */
 381 {
 382         atomic_inc(&inode->i_count);
 383 }
 384 
 385 /*
 386  * get additional reference to inode; caller must already hold one.
 387  */
 388 void ihold(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+388 fs/inode.c] */
 389 {
 390         WARN_ON(atomic_inc_return(&inode->i_count) < 2);
 391 }
 392 EXPORT_SYMBOL(ihold);
 393 
 394 static void inode_lru_list_add(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+394 fs/inode.c] */
 395 {
 396         if (list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru))
 397                 this_cpu_inc(nr_unused);
 398 }
 399 
 400 /*
 401  * Add inode to LRU if needed (inode is unused and clean).
 402  *
 403  * Needs inode->i_lock held.
 404  */
 405 void inode_add_lru(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+405 fs/inode.c] */
 406 {
 407         if (!(inode->i_state & (I_DIRTY_ALL | I_SYNC |
 408                                 I_FREEING | I_WILL_FREE)) &&
 409             !atomic_read(&inode->i_count) && inode->i_sb->s_flags & MS_ACTIVE)
 410                 inode_lru_list_add(inode);
 411 }
 412 
 413 
 414 static void inode_lru_list_del(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+414 fs/inode.c] */
 415 {
 416 
 417         if (list_lru_del(&inode->i_sb->s_inode_lru, &inode->i_lru))
 418                 this_cpu_dec(nr_unused);
 419 }
 420 
 421 /**
 422  * inode_sb_list_add - add inode to the superblock list of inodes
 423  * @inode: inode to add
 424  */
 425 void inode_sb_list_add(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+425 fs/inode.c] */
 426 {
 427         spin_lock(&inode->i_sb->s_inode_list_lock);
 428         list_add(&inode->i_sb_list, &inode->i_sb->s_inodes);
 429         spin_unlock(&inode->i_sb->s_inode_list_lock);
 430 }
 431 EXPORT_SYMBOL_GPL(inode_sb_list_add);
 432 
 433 static inline void inode_sb_list_del(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+433 fs/inode.c] */
 434 {
 435         if (!list_empty(&inode->i_sb_list)) {
 436                 spin_lock(&inode->i_sb->s_inode_list_lock);
 437                 list_del_init(&inode->i_sb_list);
 438                 spin_unlock(&inode->i_sb->s_inode_list_lock);
 439         }
 440 }
 441 
 442 static unsigned long hash(struct super_block *sb, unsigned long hashval)
     /* [previous][next][first][last][top][bottom][index][help] [+442 fs/inode.c] */
 443 {
 444         unsigned long tmp;
 445 
 446         tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) /
 447                         L1_CACHE_BYTES;
 448         tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift);
 449         return tmp & i_hash_mask;
 450 }
 451 
 452 /**
 453  *      __insert_inode_hash - hash an inode
 454  *      @inode: unhashed inode
 455  *      @hashval: unsigned long value used to locate this object in the
 456  *              inode_hashtable.
 457  *
 458  *      Add an inode to the inode hash for this superblock.
 459  */
 460 void __insert_inode_hash(struct inode *inode, unsigned long hashval)
     /* [previous][next][first][last][top][bottom][index][help] [+460 fs/inode.c] */
 461 {
 462         struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval);
 463 
 464         spin_lock(&inode_hash_lock);
 465         spin_lock(&inode->i_lock);
 466         hlist_add_head(&inode->i_hash, b);
 467         spin_unlock(&inode->i_lock);
 468         spin_unlock(&inode_hash_lock);
 469 }
 470 EXPORT_SYMBOL(__insert_inode_hash);
 471 
 472 /**
 473  *      __remove_inode_hash - remove an inode from the hash
 474  *      @inode: inode to unhash
 475  *
 476  *      Remove an inode from the superblock.
 477  */
 478 void __remove_inode_hash(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+478 fs/inode.c] */
 479 {
 480         spin_lock(&inode_hash_lock);
 481         spin_lock(&inode->i_lock);
 482         hlist_del_init(&inode->i_hash);
 483         spin_unlock(&inode->i_lock);
 484         spin_unlock(&inode_hash_lock);
 485 }
 486 EXPORT_SYMBOL(__remove_inode_hash);
 487 
 488 void clear_inode(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+488 fs/inode.c] */
 489 {
 490         might_sleep();
 491         /*
 492          * We have to cycle tree_lock here because reclaim can be still in the
 493          * process of removing the last page (in __delete_from_page_cache())
 494          * and we must not free mapping under it.
 495          */
 496         spin_lock_irq(&inode->i_data.tree_lock);
 497         BUG_ON(inode->i_data.nrpages);
 498         BUG_ON(inode->i_data.nrshadows);
 499         spin_unlock_irq(&inode->i_data.tree_lock);
 500         BUG_ON(!list_empty(&inode->i_data.private_list));
 501         BUG_ON(!(inode->i_state & I_FREEING));
 502         BUG_ON(inode->i_state & I_CLEAR);
 503         /* don't need i_lock here, no concurrent mods to i_state */
 504         inode->i_state = I_FREEING | I_CLEAR;
 505 }
 506 EXPORT_SYMBOL(clear_inode);
 507 
 508 /*
 509  * Free the inode passed in, removing it from the lists it is still connected
 510  * to. We remove any pages still attached to the inode and wait for any IO that
 511  * is still in progress before finally destroying the inode.
 512  *
 513  * An inode must already be marked I_FREEING so that we avoid the inode being
 514  * moved back onto lists if we race with other code that manipulates the lists
 515  * (e.g. writeback_single_inode). The caller is responsible for setting this.
 516  *
 517  * An inode must already be removed from the LRU list before being evicted from
 518  * the cache. This should occur atomically with setting the I_FREEING state
 519  * flag, so no inodes here should ever be on the LRU when being evicted.
 520  */
 521 static void evict(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+521 fs/inode.c] */
 522 {
 523         const struct super_operations *op = inode->i_sb->s_op;
 524 
 525         BUG_ON(!(inode->i_state & I_FREEING));
 526         BUG_ON(!list_empty(&inode->i_lru));
 527 
 528         if (!list_empty(&inode->i_io_list))
 529                 inode_io_list_del(inode);
 530 
 531         inode_sb_list_del(inode);
 532 
 533         /*
 534          * Wait for flusher thread to be done with the inode so that filesystem
 535          * does not start destroying it while writeback is still running. Since
 536          * the inode has I_FREEING set, flusher thread won't start new work on
 537          * the inode.  We just have to wait for running writeback to finish.
 538          */
 539         inode_wait_for_writeback(inode);
 540 
 541         if (op->evict_inode) {
 542                 op->evict_inode(inode);
 543         } else {
 544                 truncate_inode_pages_final(&inode->i_data);
 545                 clear_inode(inode);
 546         }
 547         if (S_ISBLK(inode->i_mode) && inode->i_bdev)
 548                 bd_forget(inode);
 549         if (S_ISCHR(inode->i_mode) && inode->i_cdev)
 550                 cd_forget(inode);
 551 
 552         remove_inode_hash(inode);
 553 
 554         spin_lock(&inode->i_lock);
 555         wake_up_bit(&inode->i_state, __I_NEW);
 556         BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
 557         spin_unlock(&inode->i_lock);
 558 
 559         destroy_inode(inode);
 560 }
 561 
 562 /*
 563  * dispose_list - dispose of the contents of a local list
 564  * @head: the head of the list to free
 565  *
 566  * Dispose-list gets a local list with local inodes in it, so it doesn't
 567  * need to worry about list corruption and SMP locks.
 568  */
 569 static void dispose_list(struct list_head *head)
     /* [previous][next][first][last][top][bottom][index][help] [+569 fs/inode.c] */
 570 {
 571         while (!list_empty(head)) {
 572                 struct inode *inode;
 573 
 574                 inode = list_first_entry(head, struct inode, i_lru);
 575                 list_del_init(&inode->i_lru);
 576 
 577                 evict(inode);
 578                 cond_resched();
 579         }
 580 }
 581 
 582 /**
 583  * evict_inodes - evict all evictable inodes for a superblock
 584  * @sb:         superblock to operate on
 585  *
 586  * Make sure that no inodes with zero refcount are retained.  This is
 587  * called by superblock shutdown after having MS_ACTIVE flag removed,
 588  * so any inode reaching zero refcount during or after that call will
 589  * be immediately evicted.
 590  */
 591 void evict_inodes(struct super_block *sb)
     /* [previous][next][first][last][top][bottom][index][help] [+591 fs/inode.c] */
 592 {
 593         struct inode *inode, *next;
 594         LIST_HEAD(dispose);
 595 
 596 again:
 597         spin_lock(&sb->s_inode_list_lock);
 598         list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
 599                 if (atomic_read(&inode->i_count))
 600                         continue;
 601 
 602                 spin_lock(&inode->i_lock);
 603                 if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
 604                         spin_unlock(&inode->i_lock);
 605                         continue;
 606                 }
 607 
 608                 inode->i_state |= I_FREEING;
 609                 inode_lru_list_del(inode);
 610                 spin_unlock(&inode->i_lock);
 611                 list_add(&inode->i_lru, &dispose);
 612 
 613                 /*
 614                  * We can have a ton of inodes to evict at unmount time given
 615                  * enough memory, check to see if we need to go to sleep for a
 616                  * bit so we don't livelock.
 617                  */
 618                 if (need_resched()) {
 619                         spin_unlock(&sb->s_inode_list_lock);
 620                         cond_resched();
 621                         dispose_list(&dispose);
 622                         goto again;
 623                 }
 624         }
 625         spin_unlock(&sb->s_inode_list_lock);
 626 
 627         dispose_list(&dispose);
 628 }
 629 
 630 /**
 631  * invalidate_inodes    - attempt to free all inodes on a superblock
 632  * @sb:         superblock to operate on
 633  * @kill_dirty: flag to guide handling of dirty inodes
 634  *
 635  * Attempts to free all inodes for a given superblock.  If there were any
 636  * busy inodes return a non-zero value, else zero.
 637  * If @kill_dirty is set, discard dirty inodes too, otherwise treat
 638  * them as busy.
 639  */
 640 int invalidate_inodes(struct super_block *sb, bool kill_dirty)
     /* [previous][next][first][last][top][bottom][index][help] [+640 fs/inode.c] */
 641 {
 642         int busy = 0;
 643         struct inode *inode, *next;
 644         LIST_HEAD(dispose);
 645 
 646         spin_lock(&sb->s_inode_list_lock);
 647         list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
 648                 spin_lock(&inode->i_lock);
 649                 if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
 650                         spin_unlock(&inode->i_lock);
 651                         continue;
 652                 }
 653                 if (inode->i_state & I_DIRTY_ALL && !kill_dirty) {
 654                         spin_unlock(&inode->i_lock);
 655                         busy = 1;
 656                         continue;
 657                 }
 658                 if (atomic_read(&inode->i_count)) {
 659                         spin_unlock(&inode->i_lock);
 660                         busy = 1;
 661                         continue;
 662                 }
 663 
 664                 inode->i_state |= I_FREEING;
 665                 inode_lru_list_del(inode);
 666                 spin_unlock(&inode->i_lock);
 667                 list_add(&inode->i_lru, &dispose);
 668         }
 669         spin_unlock(&sb->s_inode_list_lock);
 670 
 671         dispose_list(&dispose);
 672 
 673         return busy;
 674 }
 675 
 676 /*
 677  * Isolate the inode from the LRU in preparation for freeing it.
 678  *
 679  * Any inodes which are pinned purely because of attached pagecache have their
 680  * pagecache removed.  If the inode has metadata buffers attached to
 681  * mapping->private_list then try to remove them.
 682  *
 683  * If the inode has the I_REFERENCED flag set, then it means that it has been
 684  * used recently - the flag is set in iput_final(). When we encounter such an
 685  * inode, clear the flag and move it to the back of the LRU so it gets another
 686  * pass through the LRU before it gets reclaimed. This is necessary because of
 687  * the fact we are doing lazy LRU updates to minimise lock contention so the
 688  * LRU does not have strict ordering. Hence we don't want to reclaim inodes
 689  * with this flag set because they are the inodes that are out of order.
 690  */
 691 static enum lru_status inode_lru_isolate(struct list_head *item,
     /* [previous][next][first][last][top][bottom][index][help] [+691 fs/inode.c] */
 692                 struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
 693 {
 694         struct list_head *freeable = arg;
 695         struct inode    *inode = container_of(item, struct inode, i_lru);
 696 
 697         /*
 698          * we are inverting the lru lock/inode->i_lock here, so use a trylock.
 699          * If we fail to get the lock, just skip it.
 700          */
 701         if (!spin_trylock(&inode->i_lock))
 702                 return LRU_SKIP;
 703 
 704         /*
 705          * Referenced or dirty inodes are still in use. Give them another pass
 706          * through the LRU as we canot reclaim them now.
 707          */
 708         if (atomic_read(&inode->i_count) ||
 709             (inode->i_state & ~I_REFERENCED)) {
 710                 list_lru_isolate(lru, &inode->i_lru);
 711                 spin_unlock(&inode->i_lock);
 712                 this_cpu_dec(nr_unused);
 713                 return LRU_REMOVED;
 714         }
 715 
 716         /* recently referenced inodes get one more pass */
 717         if (inode->i_state & I_REFERENCED) {
 718                 inode->i_state &= ~I_REFERENCED;
 719                 spin_unlock(&inode->i_lock);
 720                 return LRU_ROTATE;
 721         }
 722 
 723         if (inode_has_buffers(inode) || inode->i_data.nrpages) {
 724                 __iget(inode);
 725                 spin_unlock(&inode->i_lock);
 726                 spin_unlock(lru_lock);
 727                 if (remove_inode_buffers(inode)) {
 728                         unsigned long reap;
 729                         reap = invalidate_mapping_pages(&inode->i_data, 0, -1);
 730                         if (current_is_kswapd())
 731                                 __count_vm_events(KSWAPD_INODESTEAL, reap);
 732                         else
 733                                 __count_vm_events(PGINODESTEAL, reap);
 734                         if (current->reclaim_state)
 735                                 current->reclaim_state->reclaimed_slab += reap;
 736                 }
 737                 iput(inode);
 738                 spin_lock(lru_lock);
 739                 return LRU_RETRY;
 740         }
 741 
 742         WARN_ON(inode->i_state & I_NEW);
 743         inode->i_state |= I_FREEING;
 744         list_lru_isolate_move(lru, &inode->i_lru, freeable);
 745         spin_unlock(&inode->i_lock);
 746 
 747         this_cpu_dec(nr_unused);
 748         return LRU_REMOVED;
 749 }
 750 
 751 /*
 752  * Walk the superblock inode LRU for freeable inodes and attempt to free them.
 753  * This is called from the superblock shrinker function with a number of inodes
 754  * to trim from the LRU. Inodes to be freed are moved to a temporary list and
 755  * then are freed outside inode_lock by dispose_list().
 756  */
 757 long prune_icache_sb(struct super_block *sb, struct shrink_control *sc)
     /* [previous][next][first][last][top][bottom][index][help] [+757 fs/inode.c] */
 758 {
 759         LIST_HEAD(freeable);
 760         long freed;
 761 
 762         freed = list_lru_shrink_walk(&sb->s_inode_lru, sc,
 763                                      inode_lru_isolate, &freeable);
 764         dispose_list(&freeable);
 765         return freed;
 766 }
 767 
 768 static void __wait_on_freeing_inode(struct inode *inode);
 769 /*
 770  * Called with the inode lock held.
 771  */
 772 static struct inode *find_inode(struct super_block *sb,
     /* [previous][next][first][last][top][bottom][index][help] [+772 fs/inode.c] */
 773                                 struct hlist_head *head,
 774                                 int (*test)(struct inode *, void *),
 775                                 void *data)
 776 {
 777         struct inode *inode = NULL;
 778 
 779 repeat:
 780         hlist_for_each_entry(inode, head, i_hash) {
 781                 if (inode->i_sb != sb)
 782                         continue;
 783                 if (!test(inode, data))
 784                         continue;
 785                 spin_lock(&inode->i_lock);
 786                 if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
 787                         __wait_on_freeing_inode(inode);
 788                         goto repeat;
 789                 }
 790                 __iget(inode);
 791                 spin_unlock(&inode->i_lock);
 792                 return inode;
 793         }
 794         return NULL;
 795 }
 796 
 797 /*
 798  * find_inode_fast is the fast path version of find_inode, see the comment at
 799  * iget_locked for details.
 800  */
 801 static struct inode *find_inode_fast(struct super_block *sb,
     /* [previous][next][first][last][top][bottom][index][help] [+801 fs/inode.c] */
 802                                 struct hlist_head *head, unsigned long ino)
 803 {
 804         struct inode *inode = NULL;
 805 
 806 repeat:
 807         hlist_for_each_entry(inode, head, i_hash) {
 808                 if (inode->i_ino != ino)
 809                         continue;
 810                 if (inode->i_sb != sb)
 811                         continue;
 812                 spin_lock(&inode->i_lock);
 813                 if (inode->i_state & (I_FREEING|I_WILL_FREE)) {
 814                         __wait_on_freeing_inode(inode);
 815                         goto repeat;
 816                 }
 817                 __iget(inode);
 818                 spin_unlock(&inode->i_lock);
 819                 return inode;
 820         }
 821         return NULL;
 822 }
 823 
 824 /*
 825  * Each cpu owns a range of LAST_INO_BATCH numbers.
 826  * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations,
 827  * to renew the exhausted range.
 828  *
 829  * This does not significantly increase overflow rate because every CPU can
 830  * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is
 831  * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the
 832  * 2^32 range, and is a worst-case. Even a 50% wastage would only increase
 833  * overflow rate by 2x, which does not seem too significant.
 834  *
 835  * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
 836  * error if st_ino won't fit in target struct field. Use 32bit counter
 837  * here to attempt to avoid that.
 838  */
 839 #define LAST_INO_BATCH 1024
 840 static DEFINE_PER_CPU(unsigned int, last_ino);
 841 
 842 unsigned int get_next_ino(void)
     /* [previous][next][first][last][top][bottom][index][help] [+842 fs/inode.c] */
 843 {
 844         unsigned int *p = &get_cpu_var(last_ino);
 845         unsigned int res = *p;
 846 
 847 #ifdef CONFIG_SMP
 848         if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) {
 849                 static atomic_t shared_last_ino;
 850                 int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino);
 851 
 852                 res = next - LAST_INO_BATCH;
 853         }
 854 #endif
 855 
 856         res++;
 857         /* get_next_ino should not provide a 0 inode number */
 858         if (unlikely(!res))
 859                 res++;
 860         *p = res;
 861         put_cpu_var(last_ino);
 862         return res;
 863 }
 864 EXPORT_SYMBOL(get_next_ino);
 865 
 866 /**
 867  *      new_inode_pseudo        - obtain an inode
 868  *      @sb: superblock
 869  *
 870  *      Allocates a new inode for given superblock.
 871  *      Inode wont be chained in superblock s_inodes list
 872  *      This means :
 873  *      - fs can't be unmount
 874  *      - quotas, fsnotify, writeback can't work
 875  */
 876 struct inode *new_inode_pseudo(struct super_block *sb)
     /* [previous][next][first][last][top][bottom][index][help] [+876 fs/inode.c] */
 877 {
 878         struct inode *inode = alloc_inode(sb);
 879 
 880         if (inode) {
 881                 spin_lock(&inode->i_lock);
 882                 inode->i_state = 0;
 883                 spin_unlock(&inode->i_lock);
 884                 INIT_LIST_HEAD(&inode->i_sb_list);
 885         }
 886         return inode;
 887 }
 888 
 889 /**
 890  *      new_inode       - obtain an inode
 891  *      @sb: superblock
 892  *
 893  *      Allocates a new inode for given superblock. The default gfp_mask
 894  *      for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE.
 895  *      If HIGHMEM pages are unsuitable or it is known that pages allocated
 896  *      for the page cache are not reclaimable or migratable,
 897  *      mapping_set_gfp_mask() must be called with suitable flags on the
 898  *      newly created inode's mapping
 899  *
 900  */
 901 struct inode *new_inode(struct super_block *sb)
     /* [previous][next][first][last][top][bottom][index][help] [+901 fs/inode.c] */
 902 {
 903         struct inode *inode;
 904 
 905         spin_lock_prefetch(&sb->s_inode_list_lock);
 906 
 907         inode = new_inode_pseudo(sb);
 908         if (inode)
 909                 inode_sb_list_add(inode);
 910         return inode;
 911 }
 912 EXPORT_SYMBOL(new_inode);
 913 
 914 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 915 void lockdep_annotate_inode_mutex_key(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+915 fs/inode.c] */
 916 {
 917         if (S_ISDIR(inode->i_mode)) {
 918                 struct file_system_type *type = inode->i_sb->s_type;
 919 
 920                 /* Set new key only if filesystem hasn't already changed it */
 921                 if (lockdep_match_class(&inode->i_mutex, &type->i_mutex_key)) {
 922                         /*
 923                          * ensure nobody is actually holding i_mutex
 924                          */
 925                         mutex_destroy(&inode->i_mutex);
 926                         mutex_init(&inode->i_mutex);
 927                         lockdep_set_class(&inode->i_mutex,
 928                                           &type->i_mutex_dir_key);
 929                 }
 930         }
 931 }
 932 EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key);
 933 #endif
 934 
 935 /**
 936  * unlock_new_inode - clear the I_NEW state and wake up any waiters
 937  * @inode:      new inode to unlock
 938  *
 939  * Called when the inode is fully initialised to clear the new state of the
 940  * inode and wake up anyone waiting for the inode to finish initialisation.
 941  */
 942 void unlock_new_inode(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+942 fs/inode.c] */
 943 {
 944         lockdep_annotate_inode_mutex_key(inode);
 945         spin_lock(&inode->i_lock);
 946         WARN_ON(!(inode->i_state & I_NEW));
 947         inode->i_state &= ~I_NEW;
 948         smp_mb();
 949         wake_up_bit(&inode->i_state, __I_NEW);
 950         spin_unlock(&inode->i_lock);
 951 }
 952 EXPORT_SYMBOL(unlock_new_inode);
 953 
 954 /**
 955  * lock_two_nondirectories - take two i_mutexes on non-directory objects
 956  *
 957  * Lock any non-NULL argument that is not a directory.
 958  * Zero, one or two objects may be locked by this function.
 959  *
 960  * @inode1: first inode to lock
 961  * @inode2: second inode to lock
 962  */
 963 void lock_two_nondirectories(struct inode *inode1, struct inode *inode2)
     /* [previous][next][first][last][top][bottom][index][help] [+963 fs/inode.c] */
 964 {
 965         if (inode1 > inode2)
 966                 swap(inode1, inode2);
 967 
 968         if (inode1 && !S_ISDIR(inode1->i_mode))
 969                 mutex_lock(&inode1->i_mutex);
 970         if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
 971                 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_NONDIR2);
 972 }
 973 EXPORT_SYMBOL(lock_two_nondirectories);
 974 
 975 /**
 976  * unlock_two_nondirectories - release locks from lock_two_nondirectories()
 977  * @inode1: first inode to unlock
 978  * @inode2: second inode to unlock
 979  */
 980 void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2)
     /* [previous][next][first][last][top][bottom][index][help] [+980 fs/inode.c] */
 981 {
 982         if (inode1 && !S_ISDIR(inode1->i_mode))
 983                 mutex_unlock(&inode1->i_mutex);
 984         if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1)
 985                 mutex_unlock(&inode2->i_mutex);
 986 }
 987 EXPORT_SYMBOL(unlock_two_nondirectories);
 988 
 989 /**
 990  * iget5_locked - obtain an inode from a mounted file system
 991  * @sb:         super block of file system
 992  * @hashval:    hash value (usually inode number) to get
 993  * @test:       callback used for comparisons between inodes
 994  * @set:        callback used to initialize a new struct inode
 995  * @data:       opaque data pointer to pass to @test and @set
 996  *
 997  * Search for the inode specified by @hashval and @data in the inode cache,
 998  * and if present it is return it with an increased reference count. This is
 999  * a generalized version of iget_locked() for file systems where the inode
1000  * number is not sufficient for unique identification of an inode.
1001  *
1002  * If the inode is not in cache, allocate a new inode and return it locked,
1003  * hashed, and with the I_NEW flag set. The file system gets to fill it in
1004  * before unlocking it via unlock_new_inode().
1005  *
1006  * Note both @test and @set are called with the inode_hash_lock held, so can't
1007  * sleep.
1008  */
1009 struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
     /* [previous][next][first][last][top][bottom][index][help] [+1009 fs/inode.c] */
1010                 int (*test)(struct inode *, void *),
1011                 int (*set)(struct inode *, void *), void *data)
1012 {
1013         struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1014         struct inode *inode;
1015 
1016         spin_lock(&inode_hash_lock);
1017         inode = find_inode(sb, head, test, data);
1018         spin_unlock(&inode_hash_lock);
1019 
1020         if (inode) {
1021                 wait_on_inode(inode);
1022                 return inode;
1023         }
1024 
1025         inode = alloc_inode(sb);
1026         if (inode) {
1027                 struct inode *old;
1028 
1029                 spin_lock(&inode_hash_lock);
1030                 /* We released the lock, so.. */
1031                 old = find_inode(sb, head, test, data);
1032                 if (!old) {
1033                         if (set(inode, data))
1034                                 goto set_failed;
1035 
1036                         spin_lock(&inode->i_lock);
1037                         inode->i_state = I_NEW;
1038                         hlist_add_head(&inode->i_hash, head);
1039                         spin_unlock(&inode->i_lock);
1040                         inode_sb_list_add(inode);
1041                         spin_unlock(&inode_hash_lock);
1042 
1043                         /* Return the locked inode with I_NEW set, the
1044                          * caller is responsible for filling in the contents
1045                          */
1046                         return inode;
1047                 }
1048 
1049                 /*
1050                  * Uhhuh, somebody else created the same inode under
1051                  * us. Use the old inode instead of the one we just
1052                  * allocated.
1053                  */
1054                 spin_unlock(&inode_hash_lock);
1055                 destroy_inode(inode);
1056                 inode = old;
1057                 wait_on_inode(inode);
1058         }
1059         return inode;
1060 
1061 set_failed:
1062         spin_unlock(&inode_hash_lock);
1063         destroy_inode(inode);
1064         return NULL;
1065 }
1066 EXPORT_SYMBOL(iget5_locked);
1067 
1068 /**
1069  * iget_locked - obtain an inode from a mounted file system
1070  * @sb:         super block of file system
1071  * @ino:        inode number to get
1072  *
1073  * Search for the inode specified by @ino in the inode cache and if present
1074  * return it with an increased reference count. This is for file systems
1075  * where the inode number is sufficient for unique identification of an inode.
1076  *
1077  * If the inode is not in cache, allocate a new inode and return it locked,
1078  * hashed, and with the I_NEW flag set.  The file system gets to fill it in
1079  * before unlocking it via unlock_new_inode().
1080  */
1081 struct inode *iget_locked(struct super_block *sb, unsigned long ino)
     /* [previous][next][first][last][top][bottom][index][help] [+1081 fs/inode.c] */
1082 {
1083         struct hlist_head *head = inode_hashtable + hash(sb, ino);
1084         struct inode *inode;
1085 
1086         spin_lock(&inode_hash_lock);
1087         inode = find_inode_fast(sb, head, ino);
1088         spin_unlock(&inode_hash_lock);
1089         if (inode) {
1090                 wait_on_inode(inode);
1091                 return inode;
1092         }
1093 
1094         inode = alloc_inode(sb);
1095         if (inode) {
1096                 struct inode *old;
1097 
1098                 spin_lock(&inode_hash_lock);
1099                 /* We released the lock, so.. */
1100                 old = find_inode_fast(sb, head, ino);
1101                 if (!old) {
1102                         inode->i_ino = ino;
1103                         spin_lock(&inode->i_lock);
1104                         inode->i_state = I_NEW;
1105                         hlist_add_head(&inode->i_hash, head);
1106                         spin_unlock(&inode->i_lock);
1107                         inode_sb_list_add(inode);
1108                         spin_unlock(&inode_hash_lock);
1109 
1110                         /* Return the locked inode with I_NEW set, the
1111                          * caller is responsible for filling in the contents
1112                          */
1113                         return inode;
1114                 }
1115 
1116                 /*
1117                  * Uhhuh, somebody else created the same inode under
1118                  * us. Use the old inode instead of the one we just
1119                  * allocated.
1120                  */
1121                 spin_unlock(&inode_hash_lock);
1122                 destroy_inode(inode);
1123                 inode = old;
1124                 wait_on_inode(inode);
1125         }
1126         return inode;
1127 }
1128 EXPORT_SYMBOL(iget_locked);
1129 
1130 /*
1131  * search the inode cache for a matching inode number.
1132  * If we find one, then the inode number we are trying to
1133  * allocate is not unique and so we should not use it.
1134  *
1135  * Returns 1 if the inode number is unique, 0 if it is not.
1136  */
1137 static int test_inode_iunique(struct super_block *sb, unsigned long ino)
     /* [previous][next][first][last][top][bottom][index][help] [+1137 fs/inode.c] */
1138 {
1139         struct hlist_head *b = inode_hashtable + hash(sb, ino);
1140         struct inode *inode;
1141 
1142         spin_lock(&inode_hash_lock);
1143         hlist_for_each_entry(inode, b, i_hash) {
1144                 if (inode->i_ino == ino && inode->i_sb == sb) {
1145                         spin_unlock(&inode_hash_lock);
1146                         return 0;
1147                 }
1148         }
1149         spin_unlock(&inode_hash_lock);
1150 
1151         return 1;
1152 }
1153 
1154 /**
1155  *      iunique - get a unique inode number
1156  *      @sb: superblock
1157  *      @max_reserved: highest reserved inode number
1158  *
1159  *      Obtain an inode number that is unique on the system for a given
1160  *      superblock. This is used by file systems that have no natural
1161  *      permanent inode numbering system. An inode number is returned that
1162  *      is higher than the reserved limit but unique.
1163  *
1164  *      BUGS:
1165  *      With a large number of inodes live on the file system this function
1166  *      currently becomes quite slow.
1167  */
1168 ino_t iunique(struct super_block *sb, ino_t max_reserved)
     /* [previous][next][first][last][top][bottom][index][help] [+1168 fs/inode.c] */
1169 {
1170         /*
1171          * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW
1172          * error if st_ino won't fit in target struct field. Use 32bit counter
1173          * here to attempt to avoid that.
1174          */
1175         static DEFINE_SPINLOCK(iunique_lock);
1176         static unsigned int counter;
1177         ino_t res;
1178 
1179         spin_lock(&iunique_lock);
1180         do {
1181                 if (counter <= max_reserved)
1182                         counter = max_reserved + 1;
1183                 res = counter++;
1184         } while (!test_inode_iunique(sb, res));
1185         spin_unlock(&iunique_lock);
1186 
1187         return res;
1188 }
1189 EXPORT_SYMBOL(iunique);
1190 
1191 struct inode *igrab(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1191 fs/inode.c] */
1192 {
1193         spin_lock(&inode->i_lock);
1194         if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) {
1195                 __iget(inode);
1196                 spin_unlock(&inode->i_lock);
1197         } else {
1198                 spin_unlock(&inode->i_lock);
1199                 /*
1200                  * Handle the case where s_op->clear_inode is not been
1201                  * called yet, and somebody is calling igrab
1202                  * while the inode is getting freed.
1203                  */
1204                 inode = NULL;
1205         }
1206         return inode;
1207 }
1208 EXPORT_SYMBOL(igrab);
1209 
1210 /**
1211  * ilookup5_nowait - search for an inode in the inode cache
1212  * @sb:         super block of file system to search
1213  * @hashval:    hash value (usually inode number) to search for
1214  * @test:       callback used for comparisons between inodes
1215  * @data:       opaque data pointer to pass to @test
1216  *
1217  * Search for the inode specified by @hashval and @data in the inode cache.
1218  * If the inode is in the cache, the inode is returned with an incremented
1219  * reference count.
1220  *
1221  * Note: I_NEW is not waited upon so you have to be very careful what you do
1222  * with the returned inode.  You probably should be using ilookup5() instead.
1223  *
1224  * Note2: @test is called with the inode_hash_lock held, so can't sleep.
1225  */
1226 struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval,
     /* [previous][next][first][last][top][bottom][index][help] [+1226 fs/inode.c] */
1227                 int (*test)(struct inode *, void *), void *data)
1228 {
1229         struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1230         struct inode *inode;
1231 
1232         spin_lock(&inode_hash_lock);
1233         inode = find_inode(sb, head, test, data);
1234         spin_unlock(&inode_hash_lock);
1235 
1236         return inode;
1237 }
1238 EXPORT_SYMBOL(ilookup5_nowait);
1239 
1240 /**
1241  * ilookup5 - search for an inode in the inode cache
1242  * @sb:         super block of file system to search
1243  * @hashval:    hash value (usually inode number) to search for
1244  * @test:       callback used for comparisons between inodes
1245  * @data:       opaque data pointer to pass to @test
1246  *
1247  * Search for the inode specified by @hashval and @data in the inode cache,
1248  * and if the inode is in the cache, return the inode with an incremented
1249  * reference count.  Waits on I_NEW before returning the inode.
1250  * returned with an incremented reference count.
1251  *
1252  * This is a generalized version of ilookup() for file systems where the
1253  * inode number is not sufficient for unique identification of an inode.
1254  *
1255  * Note: @test is called with the inode_hash_lock held, so can't sleep.
1256  */
1257 struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
     /* [previous][next][first][last][top][bottom][index][help] [+1257 fs/inode.c] */
1258                 int (*test)(struct inode *, void *), void *data)
1259 {
1260         struct inode *inode = ilookup5_nowait(sb, hashval, test, data);
1261 
1262         if (inode)
1263                 wait_on_inode(inode);
1264         return inode;
1265 }
1266 EXPORT_SYMBOL(ilookup5);
1267 
1268 /**
1269  * ilookup - search for an inode in the inode cache
1270  * @sb:         super block of file system to search
1271  * @ino:        inode number to search for
1272  *
1273  * Search for the inode @ino in the inode cache, and if the inode is in the
1274  * cache, the inode is returned with an incremented reference count.
1275  */
1276 struct inode *ilookup(struct super_block *sb, unsigned long ino)
     /* [previous][next][first][last][top][bottom][index][help] [+1276 fs/inode.c] */
1277 {
1278         struct hlist_head *head = inode_hashtable + hash(sb, ino);
1279         struct inode *inode;
1280 
1281         spin_lock(&inode_hash_lock);
1282         inode = find_inode_fast(sb, head, ino);
1283         spin_unlock(&inode_hash_lock);
1284 
1285         if (inode)
1286                 wait_on_inode(inode);
1287         return inode;
1288 }
1289 EXPORT_SYMBOL(ilookup);
1290 
1291 /**
1292  * find_inode_nowait - find an inode in the inode cache
1293  * @sb:         super block of file system to search
1294  * @hashval:    hash value (usually inode number) to search for
1295  * @match:      callback used for comparisons between inodes
1296  * @data:       opaque data pointer to pass to @match
1297  *
1298  * Search for the inode specified by @hashval and @data in the inode
1299  * cache, where the helper function @match will return 0 if the inode
1300  * does not match, 1 if the inode does match, and -1 if the search
1301  * should be stopped.  The @match function must be responsible for
1302  * taking the i_lock spin_lock and checking i_state for an inode being
1303  * freed or being initialized, and incrementing the reference count
1304  * before returning 1.  It also must not sleep, since it is called with
1305  * the inode_hash_lock spinlock held.
1306  *
1307  * This is a even more generalized version of ilookup5() when the
1308  * function must never block --- find_inode() can block in
1309  * __wait_on_freeing_inode() --- or when the caller can not increment
1310  * the reference count because the resulting iput() might cause an
1311  * inode eviction.  The tradeoff is that the @match funtion must be
1312  * very carefully implemented.
1313  */
1314 struct inode *find_inode_nowait(struct super_block *sb,
     /* [previous][next][first][last][top][bottom][index][help] [+1314 fs/inode.c] */
1315                                 unsigned long hashval,
1316                                 int (*match)(struct inode *, unsigned long,
1317                                              void *),
1318                                 void *data)
1319 {
1320         struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1321         struct inode *inode, *ret_inode = NULL;
1322         int mval;
1323 
1324         spin_lock(&inode_hash_lock);
1325         hlist_for_each_entry(inode, head, i_hash) {
1326                 if (inode->i_sb != sb)
1327                         continue;
1328                 mval = match(inode, hashval, data);
1329                 if (mval == 0)
1330                         continue;
1331                 if (mval == 1)
1332                         ret_inode = inode;
1333                 goto out;
1334         }
1335 out:
1336         spin_unlock(&inode_hash_lock);
1337         return ret_inode;
1338 }
1339 EXPORT_SYMBOL(find_inode_nowait);
1340 
1341 int insert_inode_locked(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1341 fs/inode.c] */
1342 {
1343         struct super_block *sb = inode->i_sb;
1344         ino_t ino = inode->i_ino;
1345         struct hlist_head *head = inode_hashtable + hash(sb, ino);
1346 
1347         while (1) {
1348                 struct inode *old = NULL;
1349                 spin_lock(&inode_hash_lock);
1350                 hlist_for_each_entry(old, head, i_hash) {
1351                         if (old->i_ino != ino)
1352                                 continue;
1353                         if (old->i_sb != sb)
1354                                 continue;
1355                         spin_lock(&old->i_lock);
1356                         if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1357                                 spin_unlock(&old->i_lock);
1358                                 continue;
1359                         }
1360                         break;
1361                 }
1362                 if (likely(!old)) {
1363                         spin_lock(&inode->i_lock);
1364                         inode->i_state |= I_NEW;
1365                         hlist_add_head(&inode->i_hash, head);
1366                         spin_unlock(&inode->i_lock);
1367                         spin_unlock(&inode_hash_lock);
1368                         return 0;
1369                 }
1370                 __iget(old);
1371                 spin_unlock(&old->i_lock);
1372                 spin_unlock(&inode_hash_lock);
1373                 wait_on_inode(old);
1374                 if (unlikely(!inode_unhashed(old))) {
1375                         iput(old);
1376                         return -EBUSY;
1377                 }
1378                 iput(old);
1379         }
1380 }
1381 EXPORT_SYMBOL(insert_inode_locked);
1382 
1383 int insert_inode_locked4(struct inode *inode, unsigned long hashval,
     /* [previous][next][first][last][top][bottom][index][help] [+1383 fs/inode.c] */
1384                 int (*test)(struct inode *, void *), void *data)
1385 {
1386         struct super_block *sb = inode->i_sb;
1387         struct hlist_head *head = inode_hashtable + hash(sb, hashval);
1388 
1389         while (1) {
1390                 struct inode *old = NULL;
1391 
1392                 spin_lock(&inode_hash_lock);
1393                 hlist_for_each_entry(old, head, i_hash) {
1394                         if (old->i_sb != sb)
1395                                 continue;
1396                         if (!test(old, data))
1397                                 continue;
1398                         spin_lock(&old->i_lock);
1399                         if (old->i_state & (I_FREEING|I_WILL_FREE)) {
1400                                 spin_unlock(&old->i_lock);
1401                                 continue;
1402                         }
1403                         break;
1404                 }
1405                 if (likely(!old)) {
1406                         spin_lock(&inode->i_lock);
1407                         inode->i_state |= I_NEW;
1408                         hlist_add_head(&inode->i_hash, head);
1409                         spin_unlock(&inode->i_lock);
1410                         spin_unlock(&inode_hash_lock);
1411                         return 0;
1412                 }
1413                 __iget(old);
1414                 spin_unlock(&old->i_lock);
1415                 spin_unlock(&inode_hash_lock);
1416                 wait_on_inode(old);
1417                 if (unlikely(!inode_unhashed(old))) {
1418                         iput(old);
1419                         return -EBUSY;
1420                 }
1421                 iput(old);
1422         }
1423 }
1424 EXPORT_SYMBOL(insert_inode_locked4);
1425 
1426 
1427 int generic_delete_inode(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1427 fs/inode.c] */
1428 {
1429         return 1;
1430 }
1431 EXPORT_SYMBOL(generic_delete_inode);
1432 
1433 /*
1434  * Called when we're dropping the last reference
1435  * to an inode.
1436  *
1437  * Call the FS "drop_inode()" function, defaulting to
1438  * the legacy UNIX filesystem behaviour.  If it tells
1439  * us to evict inode, do so.  Otherwise, retain inode
1440  * in cache if fs is alive, sync and evict if fs is
1441  * shutting down.
1442  */
1443 static void iput_final(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1443 fs/inode.c] */
1444 {
1445         struct super_block *sb = inode->i_sb;
1446         const struct super_operations *op = inode->i_sb->s_op;
1447         int drop;
1448 
1449         WARN_ON(inode->i_state & I_NEW);
1450 
1451         if (op->drop_inode)
1452                 drop = op->drop_inode(inode);
1453         else
1454                 drop = generic_drop_inode(inode);
1455 
1456         if (!drop && (sb->s_flags & MS_ACTIVE)) {
1457                 inode->i_state |= I_REFERENCED;
1458                 inode_add_lru(inode);
1459                 spin_unlock(&inode->i_lock);
1460                 return;
1461         }
1462 
1463         if (!drop) {
1464                 inode->i_state |= I_WILL_FREE;
1465                 spin_unlock(&inode->i_lock);
1466                 write_inode_now(inode, 1);
1467                 spin_lock(&inode->i_lock);
1468                 WARN_ON(inode->i_state & I_NEW);
1469                 inode->i_state &= ~I_WILL_FREE;
1470         }
1471 
1472         inode->i_state |= I_FREEING;
1473         if (!list_empty(&inode->i_lru))
1474                 inode_lru_list_del(inode);
1475         spin_unlock(&inode->i_lock);
1476 
1477         evict(inode);
1478 }
1479 
1480 /**
1481  *      iput    - put an inode
1482  *      @inode: inode to put
1483  *
1484  *      Puts an inode, dropping its usage count. If the inode use count hits
1485  *      zero, the inode is then freed and may also be destroyed.
1486  *
1487  *      Consequently, iput() can sleep.
1488  */
1489 void iput(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1489 fs/inode.c] */
1490 {
1491         if (!inode)
1492                 return;
1493         BUG_ON(inode->i_state & I_CLEAR);
1494 retry:
1495         if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) {
1496                 if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) {
1497                         atomic_inc(&inode->i_count);
1498                         inode->i_state &= ~I_DIRTY_TIME;
1499                         spin_unlock(&inode->i_lock);
1500                         trace_writeback_lazytime_iput(inode);
1501                         mark_inode_dirty_sync(inode);
1502                         goto retry;
1503                 }
1504                 iput_final(inode);
1505         }
1506 }
1507 EXPORT_SYMBOL(iput);
1508 
1509 /**
1510  *      bmap    - find a block number in a file
1511  *      @inode: inode of file
1512  *      @block: block to find
1513  *
1514  *      Returns the block number on the device holding the inode that
1515  *      is the disk block number for the block of the file requested.
1516  *      That is, asked for block 4 of inode 1 the function will return the
1517  *      disk block relative to the disk start that holds that block of the
1518  *      file.
1519  */
1520 sector_t bmap(struct inode *inode, sector_t block)
     /* [previous][next][first][last][top][bottom][index][help] [+1520 fs/inode.c] */
1521 {
1522         sector_t res = 0;
1523         if (inode->i_mapping->a_ops->bmap)
1524                 res = inode->i_mapping->a_ops->bmap(inode->i_mapping, block);
1525         return res;
1526 }
1527 EXPORT_SYMBOL(bmap);
1528 
1529 /*
1530  * With relative atime, only update atime if the previous atime is
1531  * earlier than either the ctime or mtime or if at least a day has
1532  * passed since the last atime update.
1533  */
1534 static int relatime_need_update(struct vfsmount *mnt, struct inode *inode,
     /* [previous][next][first][last][top][bottom][index][help] [+1534 fs/inode.c] */
1535                              struct timespec now)
1536 {
1537 
1538         if (!(mnt->mnt_flags & MNT_RELATIME))
1539                 return 1;
1540         /*
1541          * Is mtime younger than atime? If yes, update atime:
1542          */
1543         if (timespec_compare(&inode->i_mtime, &inode->i_atime) >= 0)
1544                 return 1;
1545         /*
1546          * Is ctime younger than atime? If yes, update atime:
1547          */
1548         if (timespec_compare(&inode->i_ctime, &inode->i_atime) >= 0)
1549                 return 1;
1550 
1551         /*
1552          * Is the previous atime value older than a day? If yes,
1553          * update atime:
1554          */
1555         if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60)
1556                 return 1;
1557         /*
1558          * Good, we can skip the atime update:
1559          */
1560         return 0;
1561 }
1562 
1563 int generic_update_time(struct inode *inode, struct timespec *time, int flags)
     /* [previous][next][first][last][top][bottom][index][help] [+1563 fs/inode.c] */
1564 {
1565         int iflags = I_DIRTY_TIME;
1566 
1567         if (flags & S_ATIME)
1568                 inode->i_atime = *time;
1569         if (flags & S_VERSION)
1570                 inode_inc_iversion(inode);
1571         if (flags & S_CTIME)
1572                 inode->i_ctime = *time;
1573         if (flags & S_MTIME)
1574                 inode->i_mtime = *time;
1575 
1576         if (!(inode->i_sb->s_flags & MS_LAZYTIME) || (flags & S_VERSION))
1577                 iflags |= I_DIRTY_SYNC;
1578         __mark_inode_dirty(inode, iflags);
1579         return 0;
1580 }
1581 EXPORT_SYMBOL(generic_update_time);
1582 
1583 /*
1584  * This does the actual work of updating an inodes time or version.  Must have
1585  * had called mnt_want_write() before calling this.
1586  */
1587 static int update_time(struct inode *inode, struct timespec *time, int flags)
     /* [previous][next][first][last][top][bottom][index][help] [+1587 fs/inode.c] */
1588 {
1589         int (*update_time)(struct inode *, struct timespec *, int);
1590 
1591         update_time = inode->i_op->update_time ? inode->i_op->update_time :
1592                 generic_update_time;
1593 
1594         return update_time(inode, time, flags);
1595 }
1596 
1597 /**
1598  *      touch_atime     -       update the access time
1599  *      @path: the &struct path to update
1600  *      @inode: inode to update
1601  *
1602  *      Update the accessed time on an inode and mark it for writeback.
1603  *      This function automatically handles read only file systems and media,
1604  *      as well as the "noatime" flag and inode specific "noatime" markers.
1605  */
1606 bool atime_needs_update(const struct path *path, struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1606 fs/inode.c] */
1607 {
1608         struct vfsmount *mnt = path->mnt;
1609         struct timespec now;
1610 
1611         if (inode->i_flags & S_NOATIME)
1612                 return false;
1613         if (IS_NOATIME(inode))
1614                 return false;
1615         if ((inode->i_sb->s_flags & MS_NODIRATIME) && S_ISDIR(inode->i_mode))
1616                 return false;
1617 
1618         if (mnt->mnt_flags & MNT_NOATIME)
1619                 return false;
1620         if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode))
1621                 return false;
1622 
1623         now = current_fs_time(inode->i_sb);
1624 
1625         if (!relatime_need_update(mnt, inode, now))
1626                 return false;
1627 
1628         if (timespec_equal(&inode->i_atime, &now))
1629                 return false;
1630 
1631         return true;
1632 }
1633 
1634 void touch_atime(const struct path *path)
     /* [previous][next][first][last][top][bottom][index][help] [+1634 fs/inode.c] */
1635 {
1636         struct vfsmount *mnt = path->mnt;
1637         struct inode *inode = d_inode(path->dentry);
1638         struct timespec now;
1639 
1640         if (!atime_needs_update(path, inode))
1641                 return;
1642 
1643         if (!sb_start_write_trylock(inode->i_sb))
1644                 return;
1645 
1646         if (__mnt_want_write(mnt) != 0)
1647                 goto skip_update;
1648         /*
1649          * File systems can error out when updating inodes if they need to
1650          * allocate new space to modify an inode (such is the case for
1651          * Btrfs), but since we touch atime while walking down the path we
1652          * really don't care if we failed to update the atime of the file,
1653          * so just ignore the return value.
1654          * We may also fail on filesystems that have the ability to make parts
1655          * of the fs read only, e.g. subvolumes in Btrfs.
1656          */
1657         now = current_fs_time(inode->i_sb);
1658         update_time(inode, &now, S_ATIME);
1659         __mnt_drop_write(mnt);
1660 skip_update:
1661         sb_end_write(inode->i_sb);
1662 }
1663 EXPORT_SYMBOL(touch_atime);
1664 
1665 /*
1666  * The logic we want is
1667  *
1668  *      if suid or (sgid and xgrp)
1669  *              remove privs
1670  */
1671 int should_remove_suid(struct dentry *dentry)
     /* [previous][next][first][last][top][bottom][index][help] [+1671 fs/inode.c] */
1672 {
1673         umode_t mode = d_inode(dentry)->i_mode;
1674         int kill = 0;
1675 
1676         /* suid always must be killed */
1677         if (unlikely(mode & S_ISUID))
1678                 kill = ATTR_KILL_SUID;
1679 
1680         /*
1681          * sgid without any exec bits is just a mandatory locking mark; leave
1682          * it alone.  If some exec bits are set, it's a real sgid; kill it.
1683          */
1684         if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1685                 kill |= ATTR_KILL_SGID;
1686 
1687         if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
1688                 return kill;
1689 
1690         return 0;
1691 }
1692 EXPORT_SYMBOL(should_remove_suid);
1693 
1694 /*
1695  * Return mask of changes for notify_change() that need to be done as a
1696  * response to write or truncate. Return 0 if nothing has to be changed.
1697  * Negative value on error (change should be denied).
1698  */
1699 int dentry_needs_remove_privs(struct dentry *dentry)
     /* [previous][next][first][last][top][bottom][index][help] [+1699 fs/inode.c] */
1700 {
1701         struct inode *inode = d_inode(dentry);
1702         int mask = 0;
1703         int ret;
1704 
1705         if (IS_NOSEC(inode))
1706                 return 0;
1707 
1708         mask = should_remove_suid(dentry);
1709         ret = security_inode_need_killpriv(dentry);
1710         if (ret < 0)
1711                 return ret;
1712         if (ret)
1713                 mask |= ATTR_KILL_PRIV;
1714         return mask;
1715 }
1716 EXPORT_SYMBOL(dentry_needs_remove_privs);
1717 
1718 static int __remove_privs(struct dentry *dentry, int kill)
     /* [previous][next][first][last][top][bottom][index][help] [+1718 fs/inode.c] */
1719 {
1720         struct iattr newattrs;
1721 
1722         newattrs.ia_valid = ATTR_FORCE | kill;
1723         /*
1724          * Note we call this on write, so notify_change will not
1725          * encounter any conflicting delegations:
1726          */
1727         return notify_change(dentry, &newattrs, NULL);
1728 }
1729 
1730 /*
1731  * Remove special file priviledges (suid, capabilities) when file is written
1732  * to or truncated.
1733  */
1734 int file_remove_privs(struct file *file)
     /* [previous][next][first][last][top][bottom][index][help] [+1734 fs/inode.c] */
1735 {
1736         struct dentry *dentry = file->f_path.dentry;
1737         struct inode *inode = d_inode(dentry);
1738         int kill;
1739         int error = 0;
1740 
1741         /* Fast path for nothing security related */
1742         if (IS_NOSEC(inode))
1743                 return 0;
1744 
1745         kill = file_needs_remove_privs(file);
1746         if (kill < 0)
1747                 return kill;
1748         if (kill)
1749                 error = __remove_privs(dentry, kill);
1750         if (!error)
1751                 inode_has_no_xattr(inode);
1752 
1753         return error;
1754 }
1755 EXPORT_SYMBOL(file_remove_privs);
1756 
1757 /**
1758  *      file_update_time        -       update mtime and ctime time
1759  *      @file: file accessed
1760  *
1761  *      Update the mtime and ctime members of an inode and mark the inode
1762  *      for writeback.  Note that this function is meant exclusively for
1763  *      usage in the file write path of filesystems, and filesystems may
1764  *      choose to explicitly ignore update via this function with the
1765  *      S_NOCMTIME inode flag, e.g. for network filesystem where these
1766  *      timestamps are handled by the server.  This can return an error for
1767  *      file systems who need to allocate space in order to update an inode.
1768  */
1769 
1770 int file_update_time(struct file *file)
     /* [previous][next][first][last][top][bottom][index][help] [+1770 fs/inode.c] */
1771 {
1772         struct inode *inode = file_inode(file);
1773         struct timespec now;
1774         int sync_it = 0;
1775         int ret;
1776 
1777         /* First try to exhaust all avenues to not sync */
1778         if (IS_NOCMTIME(inode))
1779                 return 0;
1780 
1781         now = current_fs_time(inode->i_sb);
1782         if (!timespec_equal(&inode->i_mtime, &now))
1783                 sync_it = S_MTIME;
1784 
1785         if (!timespec_equal(&inode->i_ctime, &now))
1786                 sync_it |= S_CTIME;
1787 
1788         if (IS_I_VERSION(inode))
1789                 sync_it |= S_VERSION;
1790 
1791         if (!sync_it)
1792                 return 0;
1793 
1794         /* Finally allowed to write? Takes lock. */
1795         if (__mnt_want_write_file(file))
1796                 return 0;
1797 
1798         ret = update_time(inode, &now, sync_it);
1799         __mnt_drop_write_file(file);
1800 
1801         return ret;
1802 }
1803 EXPORT_SYMBOL(file_update_time);
1804 
1805 int inode_needs_sync(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1805 fs/inode.c] */
1806 {
1807         if (IS_SYNC(inode))
1808                 return 1;
1809         if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
1810                 return 1;
1811         return 0;
1812 }
1813 EXPORT_SYMBOL(inode_needs_sync);
1814 
1815 /*
1816  * If we try to find an inode in the inode hash while it is being
1817  * deleted, we have to wait until the filesystem completes its
1818  * deletion before reporting that it isn't found.  This function waits
1819  * until the deletion _might_ have completed.  Callers are responsible
1820  * to recheck inode state.
1821  *
1822  * It doesn't matter if I_NEW is not set initially, a call to
1823  * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list
1824  * will DTRT.
1825  */
1826 static void __wait_on_freeing_inode(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1826 fs/inode.c] */
1827 {
1828         wait_queue_head_t *wq;
1829         DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
1830         wq = bit_waitqueue(&inode->i_state, __I_NEW);
1831         prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
1832         spin_unlock(&inode->i_lock);
1833         spin_unlock(&inode_hash_lock);
1834         schedule();
1835         finish_wait(wq, &wait.wait);
1836         spin_lock(&inode_hash_lock);
1837 }
1838 
1839 static __initdata unsigned long ihash_entries;
1840 static int __init set_ihash_entries(char *str)
     /* [previous][next][first][last][top][bottom][index][help] [+1840 fs/inode.c] */
1841 {
1842         if (!str)
1843                 return 0;
1844         ihash_entries = simple_strtoul(str, &str, 0);
1845         return 1;
1846 }
1847 __setup("ihash_entries=", set_ihash_entries);
1848 
1849 /*
1850  * Initialize the waitqueues and inode hash table.
1851  */
1852 void __init inode_init_early(void)
     /* [previous][next][first][last][top][bottom][index][help] [+1852 fs/inode.c] */
1853 {
1854         unsigned int loop;
1855 
1856         /* If hashes are distributed across NUMA nodes, defer
1857          * hash allocation until vmalloc space is available.
1858          */
1859         if (hashdist)
1860                 return;
1861 
1862         inode_hashtable =
1863                 alloc_large_system_hash("Inode-cache",
1864                                         sizeof(struct hlist_head),
1865                                         ihash_entries,
1866                                         14,
1867                                         HASH_EARLY,
1868                                         &i_hash_shift,
1869                                         &i_hash_mask,
1870                                         0,
1871                                         0);
1872 
1873         for (loop = 0; loop < (1U << i_hash_shift); loop++)
1874                 INIT_HLIST_HEAD(&inode_hashtable[loop]);
1875 }
1876 
1877 void __init inode_init(void)
     /* [previous][next][first][last][top][bottom][index][help] [+1877 fs/inode.c] */
1878 {
1879         unsigned int loop;
1880 
1881         /* inode slab cache */
1882         inode_cachep = kmem_cache_create("inode_cache",
1883                                          sizeof(struct inode),
1884                                          0,
1885                                          (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
1886                                          SLAB_MEM_SPREAD),
1887                                          init_once);
1888 
1889         /* Hash may have been set up in inode_init_early */
1890         if (!hashdist)
1891                 return;
1892 
1893         inode_hashtable =
1894                 alloc_large_system_hash("Inode-cache",
1895                                         sizeof(struct hlist_head),
1896                                         ihash_entries,
1897                                         14,
1898                                         0,
1899                                         &i_hash_shift,
1900                                         &i_hash_mask,
1901                                         0,
1902                                         0);
1903 
1904         for (loop = 0; loop < (1U << i_hash_shift); loop++)
1905                 INIT_HLIST_HEAD(&inode_hashtable[loop]);
1906 }
1907 
1908 void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
     /* [previous][next][first][last][top][bottom][index][help] [+1908 fs/inode.c] */
1909 {
1910         inode->i_mode = mode;
1911         if (S_ISCHR(mode)) {
1912                 inode->i_fop = &def_chr_fops;
1913                 inode->i_rdev = rdev;
1914         } else if (S_ISBLK(mode)) {
1915                 inode->i_fop = &def_blk_fops;
1916                 inode->i_rdev = rdev;
1917         } else if (S_ISFIFO(mode))
1918                 inode->i_fop = &pipefifo_fops;
1919         else if (S_ISSOCK(mode))
1920                 ;       /* leave it no_open_fops */
1921         else
1922                 printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
1923                                   " inode %s:%lu\n", mode, inode->i_sb->s_id,
1924                                   inode->i_ino);
1925 }
1926 EXPORT_SYMBOL(init_special_inode);
1927 
1928 /**
1929  * inode_init_owner - Init uid,gid,mode for new inode according to posix standards
1930  * @inode: New inode
1931  * @dir: Directory inode
1932  * @mode: mode of the new inode
1933  */
1934 void inode_init_owner(struct inode *inode, const struct inode *dir,
     /* [previous][next][first][last][top][bottom][index][help] [+1934 fs/inode.c] */
1935                         umode_t mode)
1936 {
1937         inode->i_uid = current_fsuid();
1938         if (dir && dir->i_mode & S_ISGID) {
1939                 inode->i_gid = dir->i_gid;
1940                 if (S_ISDIR(mode))
1941                         mode |= S_ISGID;
1942         } else
1943                 inode->i_gid = current_fsgid();
1944         inode->i_mode = mode;
1945 }
1946 EXPORT_SYMBOL(inode_init_owner);
1947 
1948 /**
1949  * inode_owner_or_capable - check current task permissions to inode
1950  * @inode: inode being checked
1951  *
1952  * Return true if current either has CAP_FOWNER in a namespace with the
1953  * inode owner uid mapped, or owns the file.
1954  */
1955 bool inode_owner_or_capable(const struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1955 fs/inode.c] */
1956 {
1957         struct user_namespace *ns;
1958 
1959         if (uid_eq(current_fsuid(), inode->i_uid))
1960                 return true;
1961 
1962         ns = current_user_ns();
1963         if (ns_capable(ns, CAP_FOWNER) && kuid_has_mapping(ns, inode->i_uid))
1964                 return true;
1965         return false;
1966 }
1967 EXPORT_SYMBOL(inode_owner_or_capable);
1968 
1969 /*
1970  * Direct i/o helper functions
1971  */
1972 static void __inode_dio_wait(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1972 fs/inode.c] */
1973 {
1974         wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP);
1975         DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP);
1976 
1977         do {
1978                 prepare_to_wait(wq, &q.wait, TASK_UNINTERRUPTIBLE);
1979                 if (atomic_read(&inode->i_dio_count))
1980                         schedule();
1981         } while (atomic_read(&inode->i_dio_count));
1982         finish_wait(wq, &q.wait);
1983 }
1984 
1985 /**
1986  * inode_dio_wait - wait for outstanding DIO requests to finish
1987  * @inode: inode to wait for
1988  *
1989  * Waits for all pending direct I/O requests to finish so that we can
1990  * proceed with a truncate or equivalent operation.
1991  *
1992  * Must be called under a lock that serializes taking new references
1993  * to i_dio_count, usually by inode->i_mutex.
1994  */
1995 void inode_dio_wait(struct inode *inode)
     /* [previous][next][first][last][top][bottom][index][help] [+1995 fs/inode.c] */
1996 {
1997         if (atomic_read(&inode->i_dio_count))
1998                 __inode_dio_wait(inode);
1999 }
2000 EXPORT_SYMBOL(inode_dio_wait);
2001 
2002 /*
2003  * inode_set_flags - atomically set some inode flags
2004  *
2005  * Note: the caller should be holding i_mutex, or else be sure that
2006  * they have exclusive access to the inode structure (i.e., while the
2007  * inode is being instantiated).  The reason for the cmpxchg() loop
2008  * --- which wouldn't be necessary if all code paths which modify
2009  * i_flags actually followed this rule, is that there is at least one
2010  * code path which doesn't today so we use cmpxchg() out of an abundance
2011  * of caution.
2012  *
2013  * In the long run, i_mutex is overkill, and we should probably look
2014  * at using the i_lock spinlock to protect i_flags, and then make sure
2015  * it is so documented in include/linux/fs.h and that all code follows
2016  * the locking convention!!
2017  */
2018 void inode_set_flags(struct inode *inode, unsigned int flags,
     /* [previous][next][first][last][top][bottom][index][help] [+2018 fs/inode.c] */
2019                      unsigned int mask)
2020 {
2021         unsigned int old_flags, new_flags;
2022 
2023         WARN_ON_ONCE(flags & ~mask);
2024         do {
2025                 old_flags = ACCESS_ONCE(inode->i_flags);
2026                 new_flags = (old_flags & ~mask) | flags;
2027         } while (unlikely(cmpxchg(&inode->i_flags, old_flags,
2028                                   new_flags) != old_flags));
2029 }
2030 EXPORT_SYMBOL(inode_set_flags);

/* [previous][next][first][last][top][bottom][index][help] [+2030 fs/inode.c] */