mm/shmem.c

   1 /*
   2  * Resizable virtual memory filesystem for Linux.
   3  *
   4  * Copyright (C) 2000 Linus Torvalds.
   5  *               2000 Transmeta Corp.
   6  *               2000-2001 Christoph Rohland
   7  *               2000-2001 SAP AG
   8  *               2002 Red Hat Inc.
   9  * Copyright (C) 2002-2004 Hugh Dickins.
  10  * Copyright (C) 2002-2004 VERITAS Software Corporation.
  11  * Copyright (C) 2004 Andi Kleen, SuSE Labs
  12  *
  13  * Extended attribute support for tmpfs:
  14  * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
  15  * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
  16  *
  17  * This file is released under the GPL.
  18  */
  19
  20 /*
  21  * This virtual memory filesystem is heavily based on the ramfs. It
  22  * extends ramfs by the ability to use swap and honor resource limits
  23  * which makes it a completely usable filesystem.
  24  */
  25
  26 #include <linux/config.h>
  27 #include <linux/module.h>
  28 #include <linux/init.h>
  29 #include <linux/devfs_fs_kernel.h>
  30 #include <linux/fs.h>
  31 #include <linux/mm.h>
  32 #include <linux/mman.h>
  33 #include <linux/file.h>
  34 #include <linux/swap.h>
  35 #include <linux/pagemap.h>
  36 #include <linux/string.h>
  37 #include <linux/slab.h>
  38 #include <linux/backing-dev.h>
  39 #include <linux/shmem_fs.h>
  40 #include <linux/mount.h>
  41 #include <linux/writeback.h>
  42 #include <linux/vfs.h>
  43 #include <linux/blkdev.h>
  44 #include <linux/security.h>
  45 #include <linux/swapops.h>
  46 #include <linux/mempolicy.h>
  47 #include <linux/namei.h>
  48 #include <linux/xattr.h>
  49 #include <asm/uaccess.h>
  50 #include <asm/div64.h>
  51 #include <asm/pgtable.h>
  52
  53 /* This magic number is used in glibc for posix shared memory */
  54 #define TMPFS_MAGIC     0x01021994
  55
  56 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
  57 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
  58 #define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
  59
  60 #define SHMEM_MAX_INDEX  (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
  61 #define SHMEM_MAX_BYTES  ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
  62
  63 #define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
  64
  65 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
  66 #define SHMEM_PAGEIN     VM_READ
  67 #define SHMEM_TRUNCATE   VM_WRITE
  68
  69 /* Definition to limit shmem_truncate's steps between cond_rescheds */
  70 #define LATENCY_LIMIT    64
  71
  72 /* Pretend that each entry is of this size in directory's i_size */
  73 #define BOGO_DIRENT_SIZE 20
  74
  75 /* Keep swapped page count in private field of indirect struct page */
  76 #define nr_swapped              private
  77
  78 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
  79 enum sgp_type {
  80         SGP_QUICK,      /* don't try more than file page cache lookup */
  81         SGP_READ,       /* don't exceed i_size, don't allocate page */
  82         SGP_CACHE,      /* don't exceed i_size, may allocate page */
  83         SGP_WRITE,      /* may exceed i_size, may allocate page */
  84 };
  85
  86 static int shmem_getpage(struct inode *inode, unsigned long idx,
  87                          struct page **pagep, enum sgp_type sgp, int *type);
  88
  89 static inline struct page *shmem_dir_alloc(unsigned int gfp_mask)
  90 {
  91         /*
  92          * The above definition of ENTRIES_PER_PAGE, and the use of
  93          * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
  94          * might be reconsidered if it ever diverges from PAGE_SIZE.
  95          */
  96         return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
  97 }
  98
  99 static inline void shmem_dir_free(struct page *page)
 100 {
 101         __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
 102 }
 103
 104 static struct page **shmem_dir_map(struct page *page)
 105 {
 106         return (struct page **)kmap_atomic(page, KM_USER0);
 107 }
 108
 109 static inline void shmem_dir_unmap(struct page **dir)
 110 {
 111         kunmap_atomic(dir, KM_USER0);
 112 }
 113
 114 static swp_entry_t *shmem_swp_map(struct page *page)
 115 {
 116         return (swp_entry_t *)kmap_atomic(page, KM_USER1);
 117 }
 118
 119 static inline void shmem_swp_balance_unmap(void)
 120 {
 121         /*
 122          * When passing a pointer to an i_direct entry, to code which
 123          * also handles indirect entries and so will shmem_swp_unmap,
 124          * we must arrange for the preempt count to remain in balance.
 125          * What kmap_atomic of a lowmem page does depends on config
 126          * and architecture, so pretend to kmap_atomic some lowmem page.
 127          */
 128         (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
 129 }
 130
 131 static inline void shmem_swp_unmap(swp_entry_t *entry)
 132 {
 133         kunmap_atomic(entry, KM_USER1);
 134 }
 135
 136 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
 137 {
 138         return sb->s_fs_info;
 139 }
 140
 141 /*
 142  * shmem_file_setup pre-accounts the whole fixed size of a VM object,
 143  * for shared memory and for shared anonymous (/dev/zero) mappings
 144  * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
 145  * consistent with the pre-accounting of private mappings ...
 146  */
 147 static inline int shmem_acct_size(unsigned long flags, loff_t size)
 148 {
 149         return (flags & VM_ACCOUNT)?
 150                 security_vm_enough_memory(VM_ACCT(size)): 0;
 151 }
 152
 153 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
 154 {
 155         if (flags & VM_ACCOUNT)
 156                 vm_unacct_memory(VM_ACCT(size));
 157 }
 158
 159 /*
 160  * ... whereas tmpfs objects are accounted incrementally as
 161  * pages are allocated, in order to allow huge sparse files.
 162  * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
 163  * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
 164  */
 165 static inline int shmem_acct_block(unsigned long flags)
 166 {
 167         return (flags & VM_ACCOUNT)?
 168                 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
 169 }
 170
 171 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
 172 {
 173         if (!(flags & VM_ACCOUNT))
 174                 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
 175 }
 176
 177 static struct super_operations shmem_ops;
 178 static struct address_space_operations shmem_aops;
 179 static struct file_operations shmem_file_operations;
 180 static struct inode_operations shmem_inode_operations;
 181 static struct inode_operations shmem_dir_inode_operations;
 182 static struct inode_operations shmem_special_inode_operations;
 183 static struct vm_operations_struct shmem_vm_ops;
 184
 185 static struct backing_dev_info shmem_backing_dev_info = {
 186         .ra_pages       = 0,    /* No readahead */
 187         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
 188         .unplug_io_fn   = default_unplug_io_fn,
 189 };
 190
 191 static LIST_HEAD(shmem_swaplist);
 192 static DEFINE_SPINLOCK(shmem_swaplist_lock);
 193
 194 static void shmem_free_blocks(struct inode *inode, long pages)
 195 {
 196         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 197         if (sbinfo) {
 198                 spin_lock(&sbinfo->stat_lock);
 199                 sbinfo->free_blocks += pages;
 200                 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
 201                 spin_unlock(&sbinfo->stat_lock);
 202         }
 203 }
 204
 205 /*
 206  * shmem_recalc_inode - recalculate the size of an inode
 207  *
 208  * @inode: inode to recalc
 209  *
 210  * We have to calculate the free blocks since the mm can drop
 211  * undirtied hole pages behind our back.
 212  *
 213  * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
 214  * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
 215  *
 216  * It has to be called with the spinlock held.
 217  */
 218 static void shmem_recalc_inode(struct inode *inode)
 219 {
 220         struct shmem_inode_info *info = SHMEM_I(inode);
 221         long freed;
 222
 223         freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
 224         if (freed > 0) {
 225                 info->alloced -= freed;
 226                 shmem_unacct_blocks(info->flags, freed);
 227                 shmem_free_blocks(inode, freed);
 228         }
 229 }
 230
 231 /*
 232  * shmem_swp_entry - find the swap vector position in the info structure
 233  *
 234  * @info:  info structure for the inode
 235  * @index: index of the page to find
 236  * @page:  optional page to add to the structure. Has to be preset to
 237  *         all zeros
 238  *
 239  * If there is no space allocated yet it will return NULL when
 240  * page is NULL, else it will use the page for the needed block,
 241  * setting it to NULL on return to indicate that it has been used.
 242  *
 243  * The swap vector is organized the following way:
 244  *
 245  * There are SHMEM_NR_DIRECT entries directly stored in the
 246  * shmem_inode_info structure. So small files do not need an addional
 247  * allocation.
 248  *
 249  * For pages with index > SHMEM_NR_DIRECT there is the pointer
 250  * i_indirect which points to a page which holds in the first half
 251  * doubly indirect blocks, in the second half triple indirect blocks:
 252  *
 253  * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
 254  * following layout (for SHMEM_NR_DIRECT == 16):
 255  *
 256  * i_indirect -> dir --> 16-19
 257  *            |      +-> 20-23
 258  *            |
 259  *            +-->dir2 --> 24-27
 260  *            |        +-> 28-31
 261  *            |        +-> 32-35
 262  *            |        +-> 36-39
 263  *            |
 264  *            +-->dir3 --> 40-43
 265  *                     +-> 44-47
 266  *                     +-> 48-51
 267  *                     +-> 52-55
 268  */
 269 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
 270 {
 271         unsigned long offset;
 272         struct page **dir;
 273         struct page *subdir;
 274
 275         if (index < SHMEM_NR_DIRECT) {
 276                 shmem_swp_balance_unmap();
 277                 return info->i_direct+index;
 278         }
 279         if (!info->i_indirect) {
 280                 if (page) {
 281                         info->i_indirect = *page;
 282                         *page = NULL;
 283                 }
 284                 return NULL;                    /* need another page */
 285         }
 286
 287         index -= SHMEM_NR_DIRECT;
 288         offset = index % ENTRIES_PER_PAGE;
 289         index /= ENTRIES_PER_PAGE;
 290         dir = shmem_dir_map(info->i_indirect);
 291
 292         if (index >= ENTRIES_PER_PAGE/2) {
 293                 index -= ENTRIES_PER_PAGE/2;
 294                 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
 295                 index %= ENTRIES_PER_PAGE;
 296                 subdir = *dir;
 297                 if (!subdir) {
 298                         if (page) {
 299                                 *dir = *page;
 300                                 *page = NULL;
 301                         }
 302                         shmem_dir_unmap(dir);
 303                         return NULL;            /* need another page */
 304                 }
 305                 shmem_dir_unmap(dir);
 306                 dir = shmem_dir_map(subdir);
 307         }
 308
 309         dir += index;
 310         subdir = *dir;
 311         if (!subdir) {
 312                 if (!page || !(subdir = *page)) {
 313                         shmem_dir_unmap(dir);
 314                         return NULL;            /* need a page */
 315                 }
 316                 *dir = subdir;
 317                 *page = NULL;
 318         }
 319         shmem_dir_unmap(dir);
 320         return shmem_swp_map(subdir) + offset;
 321 }
 322
 323 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
 324 {
 325         long incdec = value? 1: -1;
 326
 327         entry->val = value;
 328         info->swapped += incdec;
 329         if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT)
 330                 kmap_atomic_to_page(entry)->nr_swapped += incdec;
 331 }
 332
 333 /*
 334  * shmem_swp_alloc - get the position of the swap entry for the page.
 335  *                   If it does not exist allocate the entry.
 336  *
 337  * @info:       info structure for the inode
 338  * @index:      index of the page to find
 339  * @sgp:        check and recheck i_size? skip allocation?
 340  */
 341 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
 342 {
 343         struct inode *inode = &info->vfs_inode;
 344         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 345         struct page *page = NULL;
 346         swp_entry_t *entry;
 347
 348         if (sgp != SGP_WRITE &&
 349             ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
 350                 return ERR_PTR(-EINVAL);
 351
 352         while (!(entry = shmem_swp_entry(info, index, &page))) {
 353                 if (sgp == SGP_READ)
 354                         return shmem_swp_map(ZERO_PAGE(0));
 355                 /*
 356                  * Test free_blocks against 1 not 0, since we have 1 data
 357                  * page (and perhaps indirect index pages) yet to allocate:
 358                  * a waste to allocate index if we cannot allocate data.
 359                  */
 360                 if (sbinfo) {
 361                         spin_lock(&sbinfo->stat_lock);
 362                         if (sbinfo->free_blocks <= 1) {
 363                                 spin_unlock(&sbinfo->stat_lock);
 364                                 return ERR_PTR(-ENOSPC);
 365                         }
 366                         sbinfo->free_blocks--;
 367                         inode->i_blocks += BLOCKS_PER_PAGE;
 368                         spin_unlock(&sbinfo->stat_lock);
 369                 }
 370
 371                 spin_unlock(&info->lock);
 372                 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
 373                 if (page) {
 374                         page->nr_swapped = 0;
 375                 }
 376                 spin_lock(&info->lock);
 377
 378                 if (!page) {
 379                         shmem_free_blocks(inode, 1);
 380                         return ERR_PTR(-ENOMEM);
 381                 }
 382                 if (sgp != SGP_WRITE &&
 383                     ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
 384                         entry = ERR_PTR(-EINVAL);
 385                         break;
 386                 }
 387                 if (info->next_index <= index)
 388                         info->next_index = index + 1;
 389         }
 390         if (page) {
 391                 /* another task gave its page, or truncated the file */
 392                 shmem_free_blocks(inode, 1);
 393                 shmem_dir_free(page);
 394         }
 395         if (info->next_index <= index && !IS_ERR(entry))
 396                 info->next_index = index + 1;
 397         return entry;
 398 }
 399
 400 /*
 401  * shmem_free_swp - free some swap entries in a directory
 402  *
 403  * @dir:   pointer to the directory
 404  * @edir:  pointer after last entry of the directory
 405  */
 406 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
 407 {
 408         swp_entry_t *ptr;
 409         int freed = 0;
 410
 411         for (ptr = dir; ptr < edir; ptr++) {
 412                 if (ptr->val) {
 413                         free_swap_and_cache(*ptr);
 414                         *ptr = (swp_entry_t){0};
 415                         freed++;
 416                 }
 417         }
 418         return freed;
 419 }
 420
 421 static int shmem_map_and_free_swp(struct page *subdir,
 422                 int offset, int limit, struct page ***dir)
 423 {
 424         swp_entry_t *ptr;
 425         int freed = 0;
 426
 427         ptr = shmem_swp_map(subdir);
 428         for (; offset < limit; offset += LATENCY_LIMIT) {
 429                 int size = limit - offset;
 430                 if (size > LATENCY_LIMIT)
 431                         size = LATENCY_LIMIT;
 432                 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
 433                 if (need_resched()) {
 434                         shmem_swp_unmap(ptr);
 435                         if (*dir) {
 436                                 shmem_dir_unmap(*dir);
 437                                 *dir = NULL;
 438                         }
 439                         cond_resched();
 440                         ptr = shmem_swp_map(subdir);
 441                 }
 442         }
 443         shmem_swp_unmap(ptr);
 444         return freed;
 445 }
 446
 447 static void shmem_free_pages(struct list_head *next)
 448 {
 449         struct page *page;
 450         int freed = 0;
 451
 452         do {
 453                 page = container_of(next, struct page, lru);
 454                 next = next->next;
 455                 shmem_dir_free(page);
 456                 freed++;
 457                 if (freed >= LATENCY_LIMIT) {
 458                         cond_resched();
 459                         freed = 0;
 460                 }
 461         } while (next);
 462 }
 463
 464 static void shmem_truncate(struct inode *inode)
 465 {
 466         struct shmem_inode_info *info = SHMEM_I(inode);
 467         unsigned long idx;
 468         unsigned long size;
 469         unsigned long limit;
 470         unsigned long stage;
 471         unsigned long diroff;
 472         struct page **dir;
 473         struct page *topdir;
 474         struct page *middir;
 475         struct page *subdir;
 476         swp_entry_t *ptr;
 477         LIST_HEAD(pages_to_free);
 478         long nr_pages_to_free = 0;
 479         long nr_swaps_freed = 0;
 480         int offset;
 481         int freed;
 482
 483         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
 484         idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 485         if (idx >= info->next_index)
 486                 return;
 487
 488         spin_lock(&info->lock);
 489         info->flags |= SHMEM_TRUNCATE;
 490         limit = info->next_index;
 491         info->next_index = idx;
 492         topdir = info->i_indirect;
 493         if (topdir && idx <= SHMEM_NR_DIRECT) {
 494                 info->i_indirect = NULL;
 495                 nr_pages_to_free++;
 496                 list_add(&topdir->lru, &pages_to_free);
 497         }
 498         spin_unlock(&info->lock);
 499
 500         if (info->swapped && idx < SHMEM_NR_DIRECT) {
 501                 ptr = info->i_direct;
 502                 size = limit;
 503                 if (size > SHMEM_NR_DIRECT)
 504                         size = SHMEM_NR_DIRECT;
 505                 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
 506         }
 507         if (!topdir)
 508                 goto done2;
 509
 510         BUG_ON(limit <= SHMEM_NR_DIRECT);
 511         limit -= SHMEM_NR_DIRECT;
 512         idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
 513         offset = idx % ENTRIES_PER_PAGE;
 514         idx -= offset;
 515
 516         dir = shmem_dir_map(topdir);
 517         stage = ENTRIES_PER_PAGEPAGE/2;
 518         if (idx < ENTRIES_PER_PAGEPAGE/2) {
 519                 middir = topdir;
 520                 diroff = idx/ENTRIES_PER_PAGE;
 521         } else {
 522                 dir += ENTRIES_PER_PAGE/2;
 523                 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
 524                 while (stage <= idx)
 525                         stage += ENTRIES_PER_PAGEPAGE;
 526                 middir = *dir;
 527                 if (*dir) {
 528                         diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
 529                                 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
 530                         if (!diroff && !offset) {
 531                                 *dir = NULL;
 532                                 nr_pages_to_free++;
 533                                 list_add(&middir->lru, &pages_to_free);
 534                         }
 535                         shmem_dir_unmap(dir);
 536                         dir = shmem_dir_map(middir);
 537                 } else {
 538                         diroff = 0;
 539                         offset = 0;
 540                         idx = stage;
 541                 }
 542         }
 543
 544         for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
 545                 if (unlikely(idx == stage)) {
 546                         shmem_dir_unmap(dir);
 547                         dir = shmem_dir_map(topdir) +
 548                             ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
 549                         while (!*dir) {
 550                                 dir++;
 551                                 idx += ENTRIES_PER_PAGEPAGE;
 552                                 if (idx >= limit)
 553                                         goto done1;
 554                         }
 555                         stage = idx + ENTRIES_PER_PAGEPAGE;
 556                         middir = *dir;
 557                         *dir = NULL;
 558                         nr_pages_to_free++;
 559                         list_add(&middir->lru, &pages_to_free);
 560                         shmem_dir_unmap(dir);
 561                         cond_resched();
 562                         dir = shmem_dir_map(middir);
 563                         diroff = 0;
 564                 }
 565                 subdir = dir[diroff];
 566                 if (subdir && subdir->nr_swapped) {
 567                         size = limit - idx;
 568                         if (size > ENTRIES_PER_PAGE)
 569                                 size = ENTRIES_PER_PAGE;
 570                         freed = shmem_map_and_free_swp(subdir,
 571                                                 offset, size, &dir);
 572                         if (!dir)
 573                                 dir = shmem_dir_map(middir);
 574                         nr_swaps_freed += freed;
 575                         if (offset)
 576                                 spin_lock(&info->lock);
 577                         subdir->nr_swapped -= freed;
 578                         if (offset)
 579                                 spin_unlock(&info->lock);
 580                         BUG_ON(subdir->nr_swapped > offset);
 581                 }
 582                 if (offset)
 583                         offset = 0;
 584                 else if (subdir) {
 585                         dir[diroff] = NULL;
 586                         nr_pages_to_free++;
 587                         list_add(&subdir->lru, &pages_to_free);
 588                 }
 589         }
 590 done1:
 591         shmem_dir_unmap(dir);
 592 done2:
 593         if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
 594                 /*
 595                  * Call truncate_inode_pages again: racing shmem_unuse_inode
 596                  * may have swizzled a page in from swap since vmtruncate or
 597                  * generic_delete_inode did it, before we lowered next_index.
 598                  * Also, though shmem_getpage checks i_size before adding to
 599                  * cache, no recheck after: so fix the narrow window there too.
 600                  */
 601                 truncate_inode_pages(inode->i_mapping, inode->i_size);
 602         }
 603
 604         spin_lock(&info->lock);
 605         info->flags &= ~SHMEM_TRUNCATE;
 606         info->swapped -= nr_swaps_freed;
 607         if (nr_pages_to_free)
 608                 shmem_free_blocks(inode, nr_pages_to_free);
 609         shmem_recalc_inode(inode);
 610         spin_unlock(&info->lock);
 611
 612         /*
 613          * Empty swap vector directory pages to be freed?
 614          */
 615         if (!list_empty(&pages_to_free)) {
 616                 pages_to_free.prev->next = NULL;
 617                 shmem_free_pages(pages_to_free.next);
 618         }
 619 }
 620
 621 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
 622 {
 623         struct inode *inode = dentry->d_inode;
 624         struct page *page = NULL;
 625         int error;
 626
 627         if (attr->ia_valid & ATTR_SIZE) {
 628                 if (attr->ia_size < inode->i_size) {
 629                         /*
 630                          * If truncating down to a partial page, then
 631                          * if that page is already allocated, hold it
 632                          * in memory until the truncation is over, so
 633                          * truncate_partial_page cannnot miss it were
 634                          * it assigned to swap.
 635                          */
 636                         if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
 637                                 (void) shmem_getpage(inode,
 638                                         attr->ia_size>>PAGE_CACHE_SHIFT,
 639                                                 &page, SGP_READ, NULL);
 640                         }
 641                         /*
 642                          * Reset SHMEM_PAGEIN flag so that shmem_truncate can
 643                          * detect if any pages might have been added to cache
 644                          * after truncate_inode_pages.  But we needn't bother
 645                          * if it's being fully truncated to zero-length: the
 646                          * nrpages check is efficient enough in that case.
 647                          */
 648                         if (attr->ia_size) {
 649                                 struct shmem_inode_info *info = SHMEM_I(inode);
 650                                 spin_lock(&info->lock);
 651                                 info->flags &= ~SHMEM_PAGEIN;
 652                                 spin_unlock(&info->lock);
 653                         }
 654                 }
 655         }
 656
 657         error = inode_change_ok(inode, attr);
 658         if (!error)
 659                 error = inode_setattr(inode, attr);
 660         if (page)
 661                 page_cache_release(page);
 662         return error;
 663 }
 664
 665 static void shmem_delete_inode(struct inode *inode)
 666 {
 667         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 668         struct shmem_inode_info *info = SHMEM_I(inode);
 669
 670         if (inode->i_op->truncate == shmem_truncate) {
 671                 shmem_unacct_size(info->flags, inode->i_size);
 672                 inode->i_size = 0;
 673                 shmem_truncate(inode);
 674                 if (!list_empty(&info->swaplist)) {
 675                         spin_lock(&shmem_swaplist_lock);
 676                         list_del_init(&info->swaplist);
 677                         spin_unlock(&shmem_swaplist_lock);
 678                 }
 679         }
 680         if (sbinfo) {
 681                 BUG_ON(inode->i_blocks);
 682                 spin_lock(&sbinfo->stat_lock);
 683                 sbinfo->free_inodes++;
 684                 spin_unlock(&sbinfo->stat_lock);
 685         }
 686         clear_inode(inode);
 687 }
 688
 689 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
 690 {
 691         swp_entry_t *ptr;
 692
 693         for (ptr = dir; ptr < edir; ptr++) {
 694                 if (ptr->val == entry.val)
 695                         return ptr - dir;
 696         }
 697         return -1;
 698 }
 699
 700 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
 701 {
 702         struct inode *inode;
 703         unsigned long idx;
 704         unsigned long size;
 705         unsigned long limit;
 706         unsigned long stage;
 707         struct page **dir;
 708         struct page *subdir;
 709         swp_entry_t *ptr;
 710         int offset;
 711
 712         idx = 0;
 713         ptr = info->i_direct;
 714         spin_lock(&info->lock);
 715         limit = info->next_index;
 716         size = limit;
 717         if (size > SHMEM_NR_DIRECT)
 718                 size = SHMEM_NR_DIRECT;
 719         offset = shmem_find_swp(entry, ptr, ptr+size);
 720         if (offset >= 0) {
 721                 shmem_swp_balance_unmap();
 722                 goto found;
 723         }
 724         if (!info->i_indirect)
 725                 goto lost2;
 726
 727         dir = shmem_dir_map(info->i_indirect);
 728         stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
 729
 730         for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
 731                 if (unlikely(idx == stage)) {
 732                         shmem_dir_unmap(dir-1);
 733                         dir = shmem_dir_map(info->i_indirect) +
 734                             ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
 735                         while (!*dir) {
 736                                 dir++;
 737                                 idx += ENTRIES_PER_PAGEPAGE;
 738                                 if (idx >= limit)
 739                                         goto lost1;
 740                         }
 741                         stage = idx + ENTRIES_PER_PAGEPAGE;
 742                         subdir = *dir;
 743                         shmem_dir_unmap(dir);
 744                         dir = shmem_dir_map(subdir);
 745                 }
 746                 subdir = *dir;
 747                 if (subdir && subdir->nr_swapped) {
 748                         ptr = shmem_swp_map(subdir);
 749                         size = limit - idx;
 750                         if (size > ENTRIES_PER_PAGE)
 751                                 size = ENTRIES_PER_PAGE;
 752                         offset = shmem_find_swp(entry, ptr, ptr+size);
 753                         if (offset >= 0) {
 754                                 shmem_dir_unmap(dir);
 755                                 goto found;
 756                         }
 757                         shmem_swp_unmap(ptr);
 758                 }
 759         }
 760 lost1:
 761         shmem_dir_unmap(dir-1);
 762 lost2:
 763         spin_unlock(&info->lock);
 764         return 0;
 765 found:
 766         idx += offset;
 767         inode = &info->vfs_inode;
 768         if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
 769                 info->flags |= SHMEM_PAGEIN;
 770                 shmem_swp_set(info, ptr + offset, 0);
 771         }
 772         shmem_swp_unmap(ptr);
 773         spin_unlock(&info->lock);
 774         /*
 775          * Decrement swap count even when the entry is left behind:
 776          * try_to_unuse will skip over mms, then reincrement count.
 777          */
 778         swap_free(entry);
 779         return 1;
 780 }
 781
 782 /*
 783  * shmem_unuse() search for an eventually swapped out shmem page.
 784  */
 785 int shmem_unuse(swp_entry_t entry, struct page *page)
 786 {
 787         struct list_head *p, *next;
 788         struct shmem_inode_info *info;
 789         int found = 0;
 790
 791         spin_lock(&shmem_swaplist_lock);
 792         list_for_each_safe(p, next, &shmem_swaplist) {
 793                 info = list_entry(p, struct shmem_inode_info, swaplist);
 794                 if (!info->swapped)
 795                         list_del_init(&info->swaplist);
 796                 else if (shmem_unuse_inode(info, entry, page)) {
 797                         /* move head to start search for next from here */
 798                         list_move_tail(&shmem_swaplist, &info->swaplist);
 799                         found = 1;
 800                         break;
 801                 }
 802         }
 803         spin_unlock(&shmem_swaplist_lock);
 804         return found;
 805 }
 806
 807 /*
 808  * Move the page from the page cache to the swap cache.
 809  */
 810 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 811 {
 812         struct shmem_inode_info *info;
 813         swp_entry_t *entry, swap;
 814         struct address_space *mapping;
 815         unsigned long index;
 816         struct inode *inode;
 817
 818         BUG_ON(!PageLocked(page));
 819         BUG_ON(page_mapped(page));
 820
 821         mapping = page->mapping;
 822         index = page->index;
 823         inode = mapping->host;
 824         info = SHMEM_I(inode);
 825         if (info->flags & VM_LOCKED)
 826                 goto redirty;
 827         swap = get_swap_page();
 828         if (!swap.val)
 829                 goto redirty;
 830
 831         spin_lock(&info->lock);
 832         shmem_recalc_inode(inode);
 833         if (index >= info->next_index) {
 834                 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
 835                 goto unlock;
 836         }
 837         entry = shmem_swp_entry(info, index, NULL);
 838         BUG_ON(!entry);
 839         BUG_ON(entry->val);
 840
 841         if (move_to_swap_cache(page, swap) == 0) {
 842                 shmem_swp_set(info, entry, swap.val);
 843                 shmem_swp_unmap(entry);
 844                 spin_unlock(&info->lock);
 845                 if (list_empty(&info->swaplist)) {
 846                         spin_lock(&shmem_swaplist_lock);
 847                         /* move instead of add in case we're racing */
 848                         list_move_tail(&info->swaplist, &shmem_swaplist);
 849                         spin_unlock(&shmem_swaplist_lock);
 850                 }
 851                 unlock_page(page);
 852                 return 0;
 853         }
 854
 855         shmem_swp_unmap(entry);
 856 unlock:
 857         spin_unlock(&info->lock);
 858         swap_free(swap);
 859 redirty:
 860         set_page_dirty(page);
 861         return WRITEPAGE_ACTIVATE;      /* Return with the page locked */
 862 }
 863
 864 #ifdef CONFIG_NUMA
 865 static struct page *shmem_swapin_async(struct shared_policy *p,
 866                                        swp_entry_t entry, unsigned long idx)
 867 {
 868         struct page *page;
 869         struct vm_area_struct pvma;
 870
 871         /* Create a pseudo vma that just contains the policy */
 872         memset(&pvma, 0, sizeof(struct vm_area_struct));
 873         pvma.vm_end = PAGE_SIZE;
 874         pvma.vm_pgoff = idx;
 875         pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
 876         page = read_swap_cache_async(entry, &pvma, 0);
 877         mpol_free(pvma.vm_policy);
 878         return page;
 879 }
 880
 881 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
 882                           unsigned long idx)
 883 {
 884         struct shared_policy *p = &info->policy;
 885         int i, num;
 886         struct page *page;
 887         unsigned long offset;
 888
 889         num = valid_swaphandles(entry, &offset);
 890         for (i = 0; i < num; offset++, i++) {
 891                 page = shmem_swapin_async(p,
 892                                 swp_entry(swp_type(entry), offset), idx);
 893                 if (!page)
 894                         break;
 895                 page_cache_release(page);
 896         }
 897         lru_add_drain();        /* Push any new pages onto the LRU now */
 898         return shmem_swapin_async(p, entry, idx);
 899 }
 900
 901 static struct page *
 902 shmem_alloc_page(unsigned long gfp, struct shmem_inode_info *info,
 903                  unsigned long idx)
 904 {
 905         struct vm_area_struct pvma;
 906         struct page *page;
 907
 908         memset(&pvma, 0, sizeof(struct vm_area_struct));
 909         pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
 910         pvma.vm_pgoff = idx;
 911         pvma.vm_end = PAGE_SIZE;
 912         page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
 913         mpol_free(pvma.vm_policy);
 914         return page;
 915 }
 916 #else
 917 static inline struct page *
 918 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
 919 {
 920         swapin_readahead(entry, 0, NULL);
 921         return read_swap_cache_async(entry, NULL, 0);
 922 }
 923
 924 static inline struct page *
 925 shmem_alloc_page(unsigned int __nocast gfp,struct shmem_inode_info *info,
 926                                  unsigned long idx)
 927 {
 928         return alloc_page(gfp | __GFP_ZERO);
 929 }
 930 #endif
 931
 932 /*
 933  * shmem_getpage - either get the page from swap or allocate a new one
 934  *
 935  * If we allocate a new one we do not mark it dirty. That's up to the
 936  * vm. If we swap it in we mark it dirty since we also free the swap
 937  * entry since a page cannot live in both the swap and page cache
 938  */
 939 static int shmem_getpage(struct inode *inode, unsigned long idx,
 940                         struct page **pagep, enum sgp_type sgp, int *type)
 941 {
 942         struct address_space *mapping = inode->i_mapping;
 943         struct shmem_inode_info *info = SHMEM_I(inode);
 944         struct shmem_sb_info *sbinfo;
 945         struct page *filepage = *pagep;
 946         struct page *swappage;
 947         swp_entry_t *entry;
 948         swp_entry_t swap;
 949         int error;
 950
 951         if (idx >= SHMEM_MAX_INDEX)
 952                 return -EFBIG;
 953         /*
 954          * Normally, filepage is NULL on entry, and either found
 955          * uptodate immediately, or allocated and zeroed, or read
 956          * in under swappage, which is then assigned to filepage.
 957          * But shmem_prepare_write passes in a locked filepage,
 958          * which may be found not uptodate by other callers too,
 959          * and may need to be copied from the swappage read in.
 960          */
 961 repeat:
 962         if (!filepage)
 963                 filepage = find_lock_page(mapping, idx);
 964         if (filepage && PageUptodate(filepage))
 965                 goto done;
 966         error = 0;
 967         if (sgp == SGP_QUICK)
 968                 goto failed;
 969
 970         spin_lock(&info->lock);
 971         shmem_recalc_inode(inode);
 972         entry = shmem_swp_alloc(info, idx, sgp);
 973         if (IS_ERR(entry)) {
 974                 spin_unlock(&info->lock);
 975                 error = PTR_ERR(entry);
 976                 goto failed;
 977         }
 978         swap = *entry;
 979
 980         if (swap.val) {
 981                 /* Look it up and read it in.. */
 982                 swappage = lookup_swap_cache(swap);
 983                 if (!swappage) {
 984                         shmem_swp_unmap(entry);
 985                         spin_unlock(&info->lock);
 986                         /* here we actually do the io */
 987                         if (type && *type == VM_FAULT_MINOR) {
 988                                 inc_page_state(pgmajfault);
 989                                 *type = VM_FAULT_MAJOR;
 990                         }
 991                         swappage = shmem_swapin(info, swap, idx);
 992                         if (!swappage) {
 993                                 spin_lock(&info->lock);
 994                                 entry = shmem_swp_alloc(info, idx, sgp);
 995                                 if (IS_ERR(entry))
 996                                         error = PTR_ERR(entry);
 997                                 else {
 998                                         if (entry->val == swap.val)
 999                                                 error = -ENOMEM;
1000                                         shmem_swp_unmap(entry);
1001                                 }
1002                                 spin_unlock(&info->lock);
1003                                 if (error)
1004                                         goto failed;
1005                                 goto repeat;
1006                         }
1007                         wait_on_page_locked(swappage);
1008                         page_cache_release(swappage);
1009                         goto repeat;
1010                 }
1011
1012                 /* We have to do this with page locked to prevent races */
1013                 if (TestSetPageLocked(swappage)) {
1014                         shmem_swp_unmap(entry);
1015                         spin_unlock(&info->lock);
1016                         wait_on_page_locked(swappage);
1017                         page_cache_release(swappage);
1018                         goto repeat;
1019                 }
1020                 if (PageWriteback(swappage)) {
1021                         shmem_swp_unmap(entry);
1022                         spin_unlock(&info->lock);
1023                         wait_on_page_writeback(swappage);
1024                         unlock_page(swappage);
1025                         page_cache_release(swappage);
1026                         goto repeat;
1027                 }
1028                 if (!PageUptodate(swappage)) {
1029                         shmem_swp_unmap(entry);
1030                         spin_unlock(&info->lock);
1031                         unlock_page(swappage);
1032                         page_cache_release(swappage);
1033                         error = -EIO;
1034                         goto failed;
1035                 }
1036
1037                 if (filepage) {
1038                         shmem_swp_set(info, entry, 0);
1039                         shmem_swp_unmap(entry);
1040                         delete_from_swap_cache(swappage);
1041                         spin_unlock(&info->lock);
1042                         copy_highpage(filepage, swappage);
1043                         unlock_page(swappage);
1044                         page_cache_release(swappage);
1045                         flush_dcache_page(filepage);
1046                         SetPageUptodate(filepage);
1047                         set_page_dirty(filepage);
1048                         swap_free(swap);
1049                 } else if (!(error = move_from_swap_cache(
1050                                 swappage, idx, mapping))) {
1051                         info->flags |= SHMEM_PAGEIN;
1052                         shmem_swp_set(info, entry, 0);
1053                         shmem_swp_unmap(entry);
1054                         spin_unlock(&info->lock);
1055                         filepage = swappage;
1056                         swap_free(swap);
1057                 } else {
1058                         shmem_swp_unmap(entry);
1059                         spin_unlock(&info->lock);
1060                         unlock_page(swappage);
1061                         page_cache_release(swappage);
1062                         if (error == -ENOMEM) {
1063                                 /* let kswapd refresh zone for GFP_ATOMICs */
1064                                 blk_congestion_wait(WRITE, HZ/50);
1065                         }
1066                         goto repeat;
1067                 }
1068         } else if (sgp == SGP_READ && !filepage) {
1069                 shmem_swp_unmap(entry);
1070                 filepage = find_get_page(mapping, idx);
1071                 if (filepage &&
1072                     (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1073                         spin_unlock(&info->lock);
1074                         wait_on_page_locked(filepage);
1075                         page_cache_release(filepage);
1076                         filepage = NULL;
1077                         goto repeat;
1078                 }
1079                 spin_unlock(&info->lock);
1080         } else {
1081                 shmem_swp_unmap(entry);
1082                 sbinfo = SHMEM_SB(inode->i_sb);
1083                 if (sbinfo) {
1084                         spin_lock(&sbinfo->stat_lock);
1085                         if (sbinfo->free_blocks == 0 ||
1086                             shmem_acct_block(info->flags)) {
1087                                 spin_unlock(&sbinfo->stat_lock);
1088                                 spin_unlock(&info->lock);
1089                                 error = -ENOSPC;
1090                                 goto failed;
1091                         }
1092                         sbinfo->free_blocks--;
1093                         inode->i_blocks += BLOCKS_PER_PAGE;
1094                         spin_unlock(&sbinfo->stat_lock);
1095                 } else if (shmem_acct_block(info->flags)) {
1096                         spin_unlock(&info->lock);
1097                         error = -ENOSPC;
1098                         goto failed;
1099                 }
1100
1101                 if (!filepage) {
1102                         spin_unlock(&info->lock);
1103                         filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1104                                                     info,
1105                                                     idx);
1106                         if (!filepage) {
1107                                 shmem_unacct_blocks(info->flags, 1);
1108                                 shmem_free_blocks(inode, 1);
1109                                 error = -ENOMEM;
1110                                 goto failed;
1111                         }
1112
1113                         spin_lock(&info->lock);
1114                         entry = shmem_swp_alloc(info, idx, sgp);
1115                         if (IS_ERR(entry))
1116                                 error = PTR_ERR(entry);
1117                         else {
1118                                 swap = *entry;
1119                                 shmem_swp_unmap(entry);
1120                         }
1121                         if (error || swap.val || 0 != add_to_page_cache_lru(
1122                                         filepage, mapping, idx, GFP_ATOMIC)) {
1123                                 spin_unlock(&info->lock);
1124                                 page_cache_release(filepage);
1125                                 shmem_unacct_blocks(info->flags, 1);
1126                                 shmem_free_blocks(inode, 1);
1127                                 filepage = NULL;
1128                                 if (error)
1129                                         goto failed;
1130                                 goto repeat;
1131                         }
1132                         info->flags |= SHMEM_PAGEIN;
1133                 }
1134
1135                 info->alloced++;
1136                 spin_unlock(&info->lock);
1137                 flush_dcache_page(filepage);
1138                 SetPageUptodate(filepage);
1139         }
1140 done:
1141         if (*pagep != filepage) {
1142                 unlock_page(filepage);
1143                 *pagep = filepage;
1144         }
1145         return 0;
1146
1147 failed:
1148         if (*pagep != filepage) {
1149                 unlock_page(filepage);
1150                 page_cache_release(filepage);
1151         }
1152         return error;
1153 }
1154
1155 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1156 {
1157         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1158         struct page *page = NULL;
1159         unsigned long idx;
1160         int error;
1161
1162         idx = (address - vma->vm_start) >> PAGE_SHIFT;
1163         idx += vma->vm_pgoff;
1164         idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1165         if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1166                 return NOPAGE_SIGBUS;
1167
1168         error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1169         if (error)
1170                 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1171
1172         mark_page_accessed(page);
1173         return page;
1174 }
1175
1176 static int shmem_populate(struct vm_area_struct *vma,
1177         unsigned long addr, unsigned long len,
1178         pgprot_t prot, unsigned long pgoff, int nonblock)
1179 {
1180         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1181         struct mm_struct *mm = vma->vm_mm;
1182         enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1183         unsigned long size;
1184
1185         size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1186         if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1187                 return -EINVAL;
1188
1189         while ((long) len > 0) {
1190                 struct page *page = NULL;
1191                 int err;
1192                 /*
1193                  * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1194                  */
1195                 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1196                 if (err)
1197                         return err;
1198                 if (page) {
1199                         mark_page_accessed(page);
1200                         err = install_page(mm, vma, addr, page, prot);
1201                         if (err) {
1202                                 page_cache_release(page);
1203                                 return err;
1204                         }
1205                 } else if (nonblock) {
1206                         err = install_file_pte(mm, vma, addr, pgoff, prot);
1207                         if (err)
1208                                 return err;
1209                 }
1210
1211                 len -= PAGE_SIZE;
1212                 addr += PAGE_SIZE;
1213                 pgoff++;
1214         }
1215         return 0;
1216 }
1217
1218 #ifdef CONFIG_NUMA
1219 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1220 {
1221         struct inode *i = vma->vm_file->f_dentry->d_inode;
1222         return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1223 }
1224
1225 struct mempolicy *
1226 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1227 {
1228         struct inode *i = vma->vm_file->f_dentry->d_inode;
1229         unsigned long idx;
1230
1231         idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1232         return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1233 }
1234 #endif
1235
1236 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1237 {
1238         struct inode *inode = file->f_dentry->d_inode;
1239         struct shmem_inode_info *info = SHMEM_I(inode);
1240         int retval = -ENOMEM;
1241
1242         spin_lock(&info->lock);
1243         if (lock && !(info->flags & VM_LOCKED)) {
1244                 if (!user_shm_lock(inode->i_size, user))
1245                         goto out_nomem;
1246                 info->flags |= VM_LOCKED;
1247         }
1248         if (!lock && (info->flags & VM_LOCKED) && user) {
1249                 user_shm_unlock(inode->i_size, user);
1250                 info->flags &= ~VM_LOCKED;
1251         }
1252         retval = 0;
1253 out_nomem:
1254         spin_unlock(&info->lock);
1255         return retval;
1256 }
1257
1258 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1259 {
1260         file_accessed(file);
1261         vma->vm_ops = &shmem_vm_ops;
1262         return 0;
1263 }
1264
1265 static struct inode *
1266 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1267 {
1268         struct inode *inode;
1269         struct shmem_inode_info *info;
1270         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1271
1272         if (sbinfo) {
1273                 spin_lock(&sbinfo->stat_lock);
1274                 if (!sbinfo->free_inodes) {
1275                         spin_unlock(&sbinfo->stat_lock);
1276                         return NULL;
1277                 }
1278                 sbinfo->free_inodes--;
1279                 spin_unlock(&sbinfo->stat_lock);
1280         }
1281
1282         inode = new_inode(sb);
1283         if (inode) {
1284                 inode->i_mode = mode;
1285                 inode->i_uid = current->fsuid;
1286                 inode->i_gid = current->fsgid;
1287                 inode->i_blksize = PAGE_CACHE_SIZE;
1288                 inode->i_blocks = 0;
1289                 inode->i_mapping->a_ops = &shmem_aops;
1290                 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1291                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1292                 info = SHMEM_I(inode);
1293                 memset(info, 0, (char *)inode - (char *)info);
1294                 spin_lock_init(&info->lock);
1295                 INIT_LIST_HEAD(&info->swaplist);
1296
1297                 switch (mode & S_IFMT) {
1298                 default:
1299                         inode->i_op = &shmem_special_inode_operations;
1300                         init_special_inode(inode, mode, dev);
1301                         break;
1302                 case S_IFREG:
1303                         inode->i_op = &shmem_inode_operations;
1304                         inode->i_fop = &shmem_file_operations;
1305                         mpol_shared_policy_init(&info->policy);
1306                         break;
1307                 case S_IFDIR:
1308                         inode->i_nlink++;
1309                         /* Some things misbehave if size == 0 on a directory */
1310                         inode->i_size = 2 * BOGO_DIRENT_SIZE;
1311                         inode->i_op = &shmem_dir_inode_operations;
1312                         inode->i_fop = &simple_dir_operations;
1313                         break;
1314                 case S_IFLNK:
1315                         /*
1316                          * Must not load anything in the rbtree,
1317                          * mpol_free_shared_policy will not be called.
1318                          */
1319                         mpol_shared_policy_init(&info->policy);
1320                         break;
1321                 }
1322         } else if (sbinfo) {
1323                 spin_lock(&sbinfo->stat_lock);
1324                 sbinfo->free_inodes++;
1325                 spin_unlock(&sbinfo->stat_lock);
1326         }
1327         return inode;
1328 }
1329
1330 #ifdef CONFIG_TMPFS
1331
1332 static int shmem_set_size(struct shmem_sb_info *sbinfo,
1333                           unsigned long max_blocks, unsigned long max_inodes)
1334 {
1335         int error;
1336         unsigned long blocks, inodes;
1337
1338         spin_lock(&sbinfo->stat_lock);
1339         blocks = sbinfo->max_blocks - sbinfo->free_blocks;
1340         inodes = sbinfo->max_inodes - sbinfo->free_inodes;
1341         error = -EINVAL;
1342         if (max_blocks < blocks)
1343                 goto out;
1344         if (max_inodes < inodes)
1345                 goto out;
1346         error = 0;
1347         sbinfo->max_blocks  = max_blocks;
1348         sbinfo->free_blocks = max_blocks - blocks;
1349         sbinfo->max_inodes  = max_inodes;
1350         sbinfo->free_inodes = max_inodes - inodes;
1351 out:
1352         spin_unlock(&sbinfo->stat_lock);
1353         return error;
1354 }
1355
1356 static struct inode_operations shmem_symlink_inode_operations;
1357 static struct inode_operations shmem_symlink_inline_operations;
1358
1359 /*
1360  * Normally tmpfs makes no use of shmem_prepare_write, but it
1361  * lets a tmpfs file be used read-write below the loop driver.
1362  */
1363 static int
1364 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1365 {
1366         struct inode *inode = page->mapping->host;
1367         return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1368 }
1369
1370 static ssize_t
1371 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1372 {
1373         struct inode    *inode = file->f_dentry->d_inode;
1374         loff_t          pos;
1375         unsigned long   written;
1376         ssize_t         err;
1377
1378         if ((ssize_t) count < 0)
1379                 return -EINVAL;
1380
1381         if (!access_ok(VERIFY_READ, buf, count))
1382                 return -EFAULT;
1383
1384         down(&inode->i_sem);
1385
1386         pos = *ppos;
1387         written = 0;
1388
1389         err = generic_write_checks(file, &pos, &count, 0);
1390         if (err || !count)
1391                 goto out;
1392
1393         err = remove_suid(file->f_dentry);
1394         if (err)
1395                 goto out;
1396
1397         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1398
1399         do {
1400                 struct page *page = NULL;
1401                 unsigned long bytes, index, offset;
1402                 char *kaddr;
1403                 int left;
1404
1405                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1406                 index = pos >> PAGE_CACHE_SHIFT;
1407                 bytes = PAGE_CACHE_SIZE - offset;
1408                 if (bytes > count)
1409                         bytes = count;
1410
1411                 /*
1412                  * We don't hold page lock across copy from user -
1413                  * what would it guard against? - so no deadlock here.
1414                  * But it still may be a good idea to prefault below.
1415                  */
1416
1417                 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1418                 if (err)
1419                         break;
1420
1421                 left = bytes;
1422                 if (PageHighMem(page)) {
1423                         volatile unsigned char dummy;
1424                         __get_user(dummy, buf);
1425                         __get_user(dummy, buf + bytes - 1);
1426
1427                         kaddr = kmap_atomic(page, KM_USER0);
1428                         left = __copy_from_user_inatomic(kaddr + offset,
1429                                                         buf, bytes);
1430                         kunmap_atomic(kaddr, KM_USER0);
1431                 }
1432                 if (left) {
1433                         kaddr = kmap(page);
1434                         left = __copy_from_user(kaddr + offset, buf, bytes);
1435                         kunmap(page);
1436                 }
1437
1438                 written += bytes;
1439                 count -= bytes;
1440                 pos += bytes;
1441                 buf += bytes;
1442                 if (pos > inode->i_size)
1443                         i_size_write(inode, pos);
1444
1445                 flush_dcache_page(page);
1446                 set_page_dirty(page);
1447                 mark_page_accessed(page);
1448                 page_cache_release(page);
1449
1450                 if (left) {
1451                         pos -= left;
1452                         written -= left;
1453                         err = -EFAULT;
1454                         break;
1455                 }
1456
1457                 /*
1458                  * Our dirty pages are not counted in nr_dirty,
1459                  * and we do not attempt to balance dirty pages.
1460                  */
1461
1462                 cond_resched();
1463         } while (count);
1464
1465         *ppos = pos;
1466         if (written)
1467                 err = written;
1468 out:
1469         up(&inode->i_sem);
1470         return err;
1471 }
1472
1473 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1474 {
1475         struct inode *inode = filp->f_dentry->d_inode;
1476         struct address_space *mapping = inode->i_mapping;
1477         unsigned long index, offset;
1478
1479         index = *ppos >> PAGE_CACHE_SHIFT;
1480         offset = *ppos & ~PAGE_CACHE_MASK;
1481
1482         for (;;) {
1483                 struct page *page = NULL;
1484                 unsigned long end_index, nr, ret;
1485                 loff_t i_size = i_size_read(inode);
1486
1487                 end_index = i_size >> PAGE_CACHE_SHIFT;
1488                 if (index > end_index)
1489                         break;
1490                 if (index == end_index) {
1491                         nr = i_size & ~PAGE_CACHE_MASK;
1492                         if (nr <= offset)
1493                                 break;
1494                 }
1495
1496                 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1497                 if (desc->error) {
1498                         if (desc->error == -EINVAL)
1499                                 desc->error = 0;
1500                         break;
1501                 }
1502
1503                 /*
1504                  * We must evaluate after, since reads (unlike writes)
1505                  * are called without i_sem protection against truncate
1506                  */
1507                 nr = PAGE_CACHE_SIZE;
1508                 i_size = i_size_read(inode);
1509                 end_index = i_size >> PAGE_CACHE_SHIFT;
1510                 if (index == end_index) {
1511                         nr = i_size & ~PAGE_CACHE_MASK;
1512                         if (nr <= offset) {
1513                                 if (page)
1514                                         page_cache_release(page);
1515                                 break;
1516                         }
1517                 }
1518                 nr -= offset;
1519
1520                 if (page) {
1521                         /*
1522                          * If users can be writing to this page using arbitrary
1523                          * virtual addresses, take care about potential aliasing
1524                          * before reading the page on the kernel side.
1525                          */
1526                         if (mapping_writably_mapped(mapping))
1527                                 flush_dcache_page(page);
1528                         /*
1529                          * Mark the page accessed if we read the beginning.
1530                          */
1531                         if (!offset)
1532                                 mark_page_accessed(page);
1533                 } else
1534                         page = ZERO_PAGE(0);
1535
1536                 /*
1537                  * Ok, we have the page, and it's up-to-date, so
1538                  * now we can copy it to user space...
1539                  *
1540                  * The actor routine returns how many bytes were actually used..
1541                  * NOTE! This may not be the same as how much of a user buffer
1542                  * we filled up (we may be padding etc), so we can only update
1543                  * "pos" here (the actor routine has to update the user buffer
1544                  * pointers and the remaining count).
1545                  */
1546                 ret = actor(desc, page, offset, nr);
1547                 offset += ret;
1548                 index += offset >> PAGE_CACHE_SHIFT;
1549                 offset &= ~PAGE_CACHE_MASK;
1550
1551                 page_cache_release(page);
1552                 if (ret != nr || !desc->count)
1553                         break;
1554
1555                 cond_resched();
1556         }
1557
1558         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1559         file_accessed(filp);
1560 }
1561
1562 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1563 {
1564         read_descriptor_t desc;
1565
1566         if ((ssize_t) count < 0)
1567                 return -EINVAL;
1568         if (!access_ok(VERIFY_WRITE, buf, count))
1569                 return -EFAULT;
1570         if (!count)
1571                 return 0;
1572
1573         desc.written = 0;
1574         desc.count = count;
1575         desc.arg.buf = buf;
1576         desc.error = 0;
1577
1578         do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1579         if (desc.written)
1580                 return desc.written;
1581         return desc.error;
1582 }
1583
1584 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
1585                          size_t count, read_actor_t actor, void *target)
1586 {
1587         read_descriptor_t desc;
1588
1589         if (!count)
1590                 return 0;
1591
1592         desc.written = 0;
1593         desc.count = count;
1594         desc.arg.data = target;
1595         desc.error = 0;
1596
1597         do_shmem_file_read(in_file, ppos, &desc, actor);
1598         if (desc.written)
1599                 return desc.written;
1600         return desc.error;
1601 }
1602
1603 static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
1604 {
1605         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1606
1607         buf->f_type = TMPFS_MAGIC;
1608         buf->f_bsize = PAGE_CACHE_SIZE;
1609         buf->f_namelen = NAME_MAX;
1610         if (sbinfo) {
1611                 spin_lock(&sbinfo->stat_lock);
1612                 buf->f_blocks = sbinfo->max_blocks;
1613                 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1614                 buf->f_files = sbinfo->max_inodes;
1615                 buf->f_ffree = sbinfo->free_inodes;
1616                 spin_unlock(&sbinfo->stat_lock);
1617         }
1618         /* else leave those fields 0 like simple_statfs */
1619         return 0;
1620 }
1621
1622 /*
1623  * File creation. Allocate an inode, and we're done..
1624  */
1625 static int
1626 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1627 {
1628         struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1629         int error = -ENOSPC;
1630
1631         if (inode) {
1632                 if (dir->i_mode & S_ISGID) {
1633                         inode->i_gid = dir->i_gid;
1634                         if (S_ISDIR(mode))
1635                                 inode->i_mode |= S_ISGID;
1636                 }
1637                 dir->i_size += BOGO_DIRENT_SIZE;
1638                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1639                 d_instantiate(dentry, inode);
1640                 dget(dentry); /* Extra count - pin the dentry in core */
1641                 error = 0;
1642         }
1643         return error;
1644 }
1645
1646 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1647 {
1648         int error;
1649
1650         if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1651                 return error;
1652         dir->i_nlink++;
1653         return 0;
1654 }
1655
1656 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1657                 struct nameidata *nd)
1658 {
1659         return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1660 }
1661
1662 /*
1663  * Link a file..
1664  */
1665 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1666 {
1667         struct inode *inode = old_dentry->d_inode;
1668         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1669
1670         /*
1671          * No ordinary (disk based) filesystem counts links as inodes;
1672          * but each new link needs a new dentry, pinning lowmem, and
1673          * tmpfs dentries cannot be pruned until they are unlinked.
1674          */
1675         if (sbinfo) {
1676                 spin_lock(&sbinfo->stat_lock);
1677                 if (!sbinfo->free_inodes) {
1678                         spin_unlock(&sbinfo->stat_lock);
1679                         return -ENOSPC;
1680                 }
1681                 sbinfo->free_inodes--;
1682                 spin_unlock(&sbinfo->stat_lock);
1683         }
1684
1685         dir->i_size += BOGO_DIRENT_SIZE;
1686         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1687         inode->i_nlink++;
1688         atomic_inc(&inode->i_count);    /* New dentry reference */
1689         dget(dentry);           /* Extra pinning count for the created dentry */
1690         d_instantiate(dentry, inode);
1691         return 0;
1692 }
1693
1694 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1695 {
1696         struct inode *inode = dentry->d_inode;
1697
1698         if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1699                 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1700                 if (sbinfo) {
1701                         spin_lock(&sbinfo->stat_lock);
1702                         sbinfo->free_inodes++;
1703                         spin_unlock(&sbinfo->stat_lock);
1704                 }
1705         }
1706
1707         dir->i_size -= BOGO_DIRENT_SIZE;
1708         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1709         inode->i_nlink--;
1710         dput(dentry);   /* Undo the count from "create" - this does all the work */
1711         return 0;
1712 }
1713
1714 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1715 {
1716         if (!simple_empty(dentry))
1717                 return -ENOTEMPTY;
1718
1719         dir->i_nlink--;
1720         return shmem_unlink(dir, dentry);
1721 }
1722
1723 /*
1724  * The VFS layer already does all the dentry stuff for rename,
1725  * we just have to decrement the usage count for the target if
1726  * it exists so that the VFS layer correctly free's it when it
1727  * gets overwritten.
1728  */
1729 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1730 {
1731         struct inode *inode = old_dentry->d_inode;
1732         int they_are_dirs = S_ISDIR(inode->i_mode);
1733
1734         if (!simple_empty(new_dentry))
1735                 return -ENOTEMPTY;
1736
1737         if (new_dentry->d_inode) {
1738                 (void) shmem_unlink(new_dir, new_dentry);
1739                 if (they_are_dirs)
1740                         old_dir->i_nlink--;
1741         } else if (they_are_dirs) {
1742                 old_dir->i_nlink--;
1743                 new_dir->i_nlink++;
1744         }
1745
1746         old_dir->i_size -= BOGO_DIRENT_SIZE;
1747         new_dir->i_size += BOGO_DIRENT_SIZE;
1748         old_dir->i_ctime = old_dir->i_mtime =
1749         new_dir->i_ctime = new_dir->i_mtime =
1750         inode->i_ctime = CURRENT_TIME;
1751         return 0;
1752 }
1753
1754 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1755 {
1756         int error;
1757         int len;
1758         struct inode *inode;
1759         struct page *page = NULL;
1760         char *kaddr;
1761         struct shmem_inode_info *info;
1762
1763         len = strlen(symname) + 1;
1764         if (len > PAGE_CACHE_SIZE)
1765                 return -ENAMETOOLONG;
1766
1767         inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1768         if (!inode)
1769                 return -ENOSPC;
1770
1771         info = SHMEM_I(inode);
1772         inode->i_size = len-1;
1773         if (len <= (char *)inode - (char *)info) {
1774                 /* do it inline */
1775                 memcpy(info, symname, len);
1776                 inode->i_op = &shmem_symlink_inline_operations;
1777         } else {
1778                 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1779                 if (error) {
1780                         iput(inode);
1781                         return error;
1782                 }
1783                 inode->i_op = &shmem_symlink_inode_operations;
1784                 kaddr = kmap_atomic(page, KM_USER0);
1785                 memcpy(kaddr, symname, len);
1786                 kunmap_atomic(kaddr, KM_USER0);
1787                 set_page_dirty(page);
1788                 page_cache_release(page);
1789         }
1790         if (dir->i_mode & S_ISGID)
1791                 inode->i_gid = dir->i_gid;
1792         dir->i_size += BOGO_DIRENT_SIZE;
1793         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1794         d_instantiate(dentry, inode);
1795         dget(dentry);
1796         return 0;
1797 }
1798
1799 static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1800 {
1801         nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1802         return 0;
1803 }
1804
1805 static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1806 {
1807         struct page *page = NULL;
1808         int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1809         nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1810         return 0;
1811 }
1812
1813 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd)
1814 {
1815         if (!IS_ERR(nd_get_link(nd))) {
1816                 struct page *page;
1817
1818                 page = find_get_page(dentry->d_inode->i_mapping, 0);
1819                 if (!page)
1820                         BUG();
1821                 kunmap(page);
1822                 mark_page_accessed(page);
1823                 page_cache_release(page);
1824                 page_cache_release(page);
1825         }
1826 }
1827
1828 static struct inode_operations shmem_symlink_inline_operations = {
1829         .readlink       = generic_readlink,
1830         .follow_link    = shmem_follow_link_inline,
1831 #ifdef CONFIG_TMPFS_XATTR
1832         .setxattr       = generic_setxattr,
1833         .getxattr       = generic_getxattr,
1834         .listxattr      = generic_listxattr,
1835         .removexattr    = generic_removexattr,
1836 #endif
1837 };
1838
1839 static struct inode_operations shmem_symlink_inode_operations = {
1840         .truncate       = shmem_truncate,
1841         .readlink       = generic_readlink,
1842         .follow_link    = shmem_follow_link,
1843         .put_link       = shmem_put_link,
1844 #ifdef CONFIG_TMPFS_XATTR
1845         .setxattr       = generic_setxattr,
1846         .getxattr       = generic_getxattr,
1847         .listxattr      = generic_listxattr,
1848         .removexattr    = generic_removexattr,
1849 #endif
1850 };
1851
1852 static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes)
1853 {
1854         char *this_char, *value, *rest;
1855
1856         while ((this_char = strsep(&options, ",")) != NULL) {
1857                 if (!*this_char)
1858                         continue;
1859                 if ((value = strchr(this_char,'=')) != NULL) {
1860                         *value++ = 0;
1861                 } else {
1862                         printk(KERN_ERR
1863                             "tmpfs: No value for mount option '%s'\n",
1864                             this_char);
1865                         return 1;
1866                 }
1867
1868                 if (!strcmp(this_char,"size")) {
1869                         unsigned long long size;
1870                         size = memparse(value,&rest);
1871                         if (*rest == '%') {
1872                                 size <<= PAGE_SHIFT;
1873                                 size *= totalram_pages;
1874                                 do_div(size, 100);
1875                                 rest++;
1876                         }
1877                         if (*rest)
1878                                 goto bad_val;
1879                         *blocks = size >> PAGE_CACHE_SHIFT;
1880                 } else if (!strcmp(this_char,"nr_blocks")) {
1881                         *blocks = memparse(value,&rest);
1882                         if (*rest)
1883                                 goto bad_val;
1884                 } else if (!strcmp(this_char,"nr_inodes")) {
1885                         *inodes = memparse(value,&rest);
1886                         if (*rest)
1887                                 goto bad_val;
1888                 } else if (!strcmp(this_char,"mode")) {
1889                         if (!mode)
1890                                 continue;
1891                         *mode = simple_strtoul(value,&rest,8);
1892                         if (*rest)
1893                                 goto bad_val;
1894                 } else if (!strcmp(this_char,"uid")) {
1895                         if (!uid)
1896                                 continue;
1897                         *uid = simple_strtoul(value,&rest,0);
1898                         if (*rest)
1899                                 goto bad_val;
1900                 } else if (!strcmp(this_char,"gid")) {
1901                         if (!gid)
1902                                 continue;
1903                         *gid = simple_strtoul(value,&rest,0);
1904                         if (*rest)
1905                                 goto bad_val;
1906                 } else {
1907                         printk(KERN_ERR "tmpfs: Bad mount option %s\n",
1908                                this_char);
1909                         return 1;
1910                 }
1911         }
1912         return 0;
1913
1914 bad_val:
1915         printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
1916                value, this_char);
1917         return 1;
1918
1919 }
1920
1921 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
1922 {
1923         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1924         unsigned long max_blocks = 0;
1925         unsigned long max_inodes = 0;
1926
1927         if (sbinfo) {
1928                 max_blocks = sbinfo->max_blocks;
1929                 max_inodes = sbinfo->max_inodes;
1930         }
1931         if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, &max_inodes))
1932                 return -EINVAL;
1933         /* Keep it simple: disallow limited <-> unlimited remount */
1934         if ((max_blocks || max_inodes) == !sbinfo)
1935                 return -EINVAL;
1936         /* But allow the pointless unlimited -> unlimited remount */
1937         if (!sbinfo)
1938                 return 0;
1939         return shmem_set_size(sbinfo, max_blocks, max_inodes);
1940 }
1941 #endif
1942
1943 static void shmem_put_super(struct super_block *sb)
1944 {
1945         kfree(sb->s_fs_info);
1946         sb->s_fs_info = NULL;
1947 }
1948
1949 #ifdef CONFIG_TMPFS_XATTR
1950 static struct xattr_handler *shmem_xattr_handlers[];
1951 #else
1952 #define shmem_xattr_handlers NULL
1953 #endif
1954
1955 static int shmem_fill_super(struct super_block *sb,
1956                             void *data, int silent)
1957 {
1958         struct inode *inode;
1959         struct dentry *root;
1960         int mode   = S_IRWXUGO | S_ISVTX;
1961         uid_t uid = current->fsuid;
1962         gid_t gid = current->fsgid;
1963         int err = -ENOMEM;
1964
1965 #ifdef CONFIG_TMPFS
1966         unsigned long blocks = 0;
1967         unsigned long inodes = 0;
1968
1969         /*
1970          * Per default we only allow half of the physical ram per
1971          * tmpfs instance, limiting inodes to one per page of lowmem;
1972          * but the internal instance is left unlimited.
1973          */
1974         if (!(sb->s_flags & MS_NOUSER)) {
1975                 blocks = totalram_pages / 2;
1976                 inodes = totalram_pages - totalhigh_pages;
1977                 if (inodes > blocks)
1978                         inodes = blocks;
1979
1980                 if (shmem_parse_options(data, &mode,
1981                                         &uid, &gid, &blocks, &inodes))
1982                         return -EINVAL;
1983         }
1984
1985         if (blocks || inodes) {
1986                 struct shmem_sb_info *sbinfo;
1987                 sbinfo = kmalloc(sizeof(struct shmem_sb_info), GFP_KERNEL);
1988                 if (!sbinfo)
1989                         return -ENOMEM;
1990                 sb->s_fs_info = sbinfo;
1991                 spin_lock_init(&sbinfo->stat_lock);
1992                 sbinfo->max_blocks = blocks;
1993                 sbinfo->free_blocks = blocks;
1994                 sbinfo->max_inodes = inodes;
1995                 sbinfo->free_inodes = inodes;
1996         }
1997         sb->s_xattr = shmem_xattr_handlers;
1998 #else
1999         sb->s_flags |= MS_NOUSER;
2000 #endif
2001
2002         sb->s_maxbytes = SHMEM_MAX_BYTES;
2003         sb->s_blocksize = PAGE_CACHE_SIZE;
2004         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2005         sb->s_magic = TMPFS_MAGIC;
2006         sb->s_op = &shmem_ops;
2007         inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2008         if (!inode)
2009                 goto failed;
2010         inode->i_uid = uid;
2011         inode->i_gid = gid;
2012         root = d_alloc_root(inode);
2013         if (!root)
2014                 goto failed_iput;
2015         sb->s_root = root;
2016         return 0;
2017
2018 failed_iput:
2019         iput(inode);
2020 failed:
2021         shmem_put_super(sb);
2022         return err;
2023 }
2024
2025 static kmem_cache_t *shmem_inode_cachep;
2026
2027 static struct inode *shmem_alloc_inode(struct super_block *sb)
2028 {
2029         struct shmem_inode_info *p;
2030         p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
2031         if (!p)
2032                 return NULL;
2033         return &p->vfs_inode;
2034 }
2035
2036 static void shmem_destroy_inode(struct inode *inode)
2037 {
2038         if ((inode->i_mode & S_IFMT) == S_IFREG) {
2039                 /* only struct inode is valid if it's an inline symlink */
2040                 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2041         }
2042         kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2043 }
2044
2045 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
2046 {
2047         struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2048
2049         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
2050             SLAB_CTOR_CONSTRUCTOR) {
2051                 inode_init_once(&p->vfs_inode);
2052         }
2053 }
2054
2055 static int init_inodecache(void)
2056 {
2057         shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2058                                 sizeof(struct shmem_inode_info),
2059                                 0, 0, init_once, NULL);
2060         if (shmem_inode_cachep == NULL)
2061                 return -ENOMEM;
2062         return 0;
2063 }
2064
2065 static void destroy_inodecache(void)
2066 {
2067         if (kmem_cache_destroy(shmem_inode_cachep))
2068                 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
2069 }
2070
2071 static struct address_space_operations shmem_aops = {
2072         .writepage      = shmem_writepage,
2073         .set_page_dirty = __set_page_dirty_nobuffers,
2074 #ifdef CONFIG_TMPFS
2075         .prepare_write  = shmem_prepare_write,
2076         .commit_write   = simple_commit_write,
2077 #endif
2078 };
2079
2080 static struct file_operations shmem_file_operations = {
2081         .mmap           = shmem_mmap,
2082 #ifdef CONFIG_TMPFS
2083         .llseek         = generic_file_llseek,
2084         .read           = shmem_file_read,
2085         .write          = shmem_file_write,
2086         .fsync          = simple_sync_file,
2087         .sendfile       = shmem_file_sendfile,
2088 #endif
2089 };
2090
2091 static struct inode_operations shmem_inode_operations = {
2092         .truncate       = shmem_truncate,
2093         .setattr        = shmem_notify_change,
2094 #ifdef CONFIG_TMPFS_XATTR
2095         .setxattr       = generic_setxattr,
2096         .getxattr       = generic_getxattr,
2097         .listxattr      = generic_listxattr,
2098         .removexattr    = generic_removexattr,
2099 #endif
2100 };
2101
2102 static struct inode_operations shmem_dir_inode_operations = {
2103 #ifdef CONFIG_TMPFS
2104         .create         = shmem_create,
2105         .lookup         = simple_lookup,
2106         .link           = shmem_link,
2107         .unlink         = shmem_unlink,
2108         .symlink        = shmem_symlink,
2109         .mkdir          = shmem_mkdir,
2110         .rmdir          = shmem_rmdir,
2111         .mknod          = shmem_mknod,
2112         .rename         = shmem_rename,
2113 #ifdef CONFIG_TMPFS_XATTR
2114         .setxattr       = generic_setxattr,
2115         .getxattr       = generic_getxattr,
2116         .listxattr      = generic_listxattr,
2117         .removexattr    = generic_removexattr,
2118 #endif
2119 #endif
2120 };
2121
2122 static struct inode_operations shmem_special_inode_operations = {
2123 #ifdef CONFIG_TMPFS_XATTR
2124         .setxattr       = generic_setxattr,
2125         .getxattr       = generic_getxattr,
2126         .listxattr      = generic_listxattr,
2127         .removexattr    = generic_removexattr,
2128 #endif
2129 };
2130
2131 static struct super_operations shmem_ops = {
2132         .alloc_inode    = shmem_alloc_inode,
2133         .destroy_inode  = shmem_destroy_inode,
2134 #ifdef CONFIG_TMPFS
2135         .statfs         = shmem_statfs,
2136         .remount_fs     = shmem_remount_fs,
2137 #endif
2138         .delete_inode   = shmem_delete_inode,
2139         .drop_inode     = generic_delete_inode,
2140         .put_super      = shmem_put_super,
2141 };
2142
2143 static struct vm_operations_struct shmem_vm_ops = {
2144         .nopage         = shmem_nopage,
2145         .populate       = shmem_populate,
2146 #ifdef CONFIG_NUMA
2147         .set_policy     = shmem_set_policy,
2148         .get_policy     = shmem_get_policy,
2149 #endif
2150 };
2151
2152
2153 #ifdef CONFIG_TMPFS_SECURITY
2154
2155 static size_t shmem_xattr_security_list(struct inode *inode, char *list, size_t list_len,
2156                                         const char *name, size_t name_len)
2157 {
2158         return security_inode_listsecurity(inode, list, list_len);
2159 }
2160
2161 static int shmem_xattr_security_get(struct inode *inode, const char *name, void *buffer, size_t size)
2162 {
2163         if (strcmp(name, "") == 0)
2164                 return -EINVAL;
2165         return security_inode_getsecurity(inode, name, buffer, size);
2166 }
2167
2168 static int shmem_xattr_security_set(struct inode *inode, const char *name, const void *value, size_t size, int flags)
2169 {
2170         if (strcmp(name, "") == 0)
2171                 return -EINVAL;
2172         return security_inode_setsecurity(inode, name, value, size, flags);
2173 }
2174
2175 static struct xattr_handler shmem_xattr_security_handler = {
2176         .prefix = XATTR_SECURITY_PREFIX,
2177         .list   = shmem_xattr_security_list,
2178         .get    = shmem_xattr_security_get,
2179         .set    = shmem_xattr_security_set,
2180 };
2181
2182 #endif  /* CONFIG_TMPFS_SECURITY */
2183
2184 #ifdef CONFIG_TMPFS_XATTR
2185
2186 static struct xattr_handler *shmem_xattr_handlers[] = {
2187 #ifdef CONFIG_TMPFS_SECURITY
2188         &shmem_xattr_security_handler,
2189 #endif
2190         NULL
2191 };
2192
2193 #endif  /* CONFIG_TMPFS_XATTR */
2194
2195 static struct super_block *shmem_get_sb(struct file_system_type *fs_type,
2196         int flags, const char *dev_name, void *data)
2197 {
2198         return get_sb_nodev(fs_type, flags, data, shmem_fill_super);
2199 }
2200
2201 static struct file_system_type tmpfs_fs_type = {
2202         .owner          = THIS_MODULE,
2203         .name           = "tmpfs",
2204         .get_sb         = shmem_get_sb,
2205         .kill_sb        = kill_litter_super,
2206 };
2207 static struct vfsmount *shm_mnt;
2208
2209 static int __init init_tmpfs(void)
2210 {
2211         int error;
2212
2213         error = init_inodecache();
2214         if (error)
2215                 goto out3;
2216
2217         error = register_filesystem(&tmpfs_fs_type);
2218         if (error) {
2219                 printk(KERN_ERR "Could not register tmpfs\n");
2220                 goto out2;
2221         }
2222 #ifdef CONFIG_TMPFS
2223         devfs_mk_dir("shm");
2224 #endif
2225         shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER,
2226                                 tmpfs_fs_type.name, NULL);
2227         if (IS_ERR(shm_mnt)) {
2228                 error = PTR_ERR(shm_mnt);
2229                 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2230                 goto out1;
2231         }
2232         return 0;
2233
2234 out1:
2235         unregister_filesystem(&tmpfs_fs_type);
2236 out2:
2237         destroy_inodecache();
2238 out3:
2239         shm_mnt = ERR_PTR(error);
2240         return error;
2241 }
2242 module_init(init_tmpfs)
2243
2244 /*
2245  * shmem_file_setup - get an unlinked file living in tmpfs
2246  *
2247  * @name: name for dentry (to be seen in /proc/<pid>/maps
2248  * @size: size to be set for the file
2249  *
2250  */
2251 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2252 {
2253         int error;
2254         struct file *file;
2255         struct inode *inode;
2256         struct dentry *dentry, *root;
2257         struct qstr this;
2258
2259         if (IS_ERR(shm_mnt))
2260                 return (void *)shm_mnt;
2261
2262         if (size < 0 || size > SHMEM_MAX_BYTES)
2263                 return ERR_PTR(-EINVAL);
2264
2265         if (shmem_acct_size(flags, size))
2266                 return ERR_PTR(-ENOMEM);
2267
2268         error = -ENOMEM;
2269         this.name = name;
2270         this.len = strlen(name);
2271         this.hash = 0; /* will go */
2272         root = shm_mnt->mnt_root;
2273         dentry = d_alloc(root, &this);
2274         if (!dentry)
2275                 goto put_memory;
2276
2277         error = -ENFILE;
2278         file = get_empty_filp();
2279         if (!file)
2280                 goto put_dentry;
2281
2282         error = -ENOSPC;
2283         inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2284         if (!inode)
2285                 goto close_file;
2286
2287         SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2288         d_instantiate(dentry, inode);
2289         inode->i_size = size;
2290         inode->i_nlink = 0;     /* It is unlinked */
2291         file->f_vfsmnt = mntget(shm_mnt);
2292         file->f_dentry = dentry;
2293         file->f_mapping = inode->i_mapping;
2294         file->f_op = &shmem_file_operations;
2295         file->f_mode = FMODE_WRITE | FMODE_READ;
2296         return file;
2297
2298 close_file:
2299         put_filp(file);
2300 put_dentry:
2301         dput(dentry);
2302 put_memory:
2303         shmem_unacct_size(flags, size);
2304         return ERR_PTR(error);
2305 }
2306
2307 /*
2308  * shmem_zero_setup - setup a shared anonymous mapping
2309  *
2310  * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2311  */
2312 int shmem_zero_setup(struct vm_area_struct *vma)
2313 {
2314         struct file *file;
2315         loff_t size = vma->vm_end - vma->vm_start;
2316
2317         file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2318         if (IS_ERR(file))
2319                 return PTR_ERR(file);
2320
2321         if (vma->vm_file)
2322                 fput(vma->vm_file);
2323         vma->vm_file = file;
2324         vma->vm_ops = &shmem_vm_ops;
2325         return 0;
2326 }