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) 2002-2011 Hugh Dickins.
  10  * Copyright (C) 2011 Google Inc.
  11  * Copyright (C) 2002-2005 VERITAS Software Corporation.
  12  * Copyright (C) 2004 Andi Kleen, SuSE Labs
  13  *
  14  * Extended attribute support for tmpfs:
  15  * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
  16  * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
  17  *
  18  * tiny-shmem:
  19  * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
  20  *
  21  * This file is released under the GPL.
  22  */
  23
  24 #include <linux/fs.h>
  25 #include <linux/init.h>
  26 #include <linux/vfs.h>
  27 #include <linux/mount.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/file.h>
  30 #include <linux/mm.h>
  31 #include <linux/export.h>
  32 #include <linux/swap.h>
  33
  34 static struct vfsmount *shm_mnt;
  35
  36 #ifdef CONFIG_SHMEM
  37 /*
  38  * This virtual memory filesystem is heavily based on the ramfs. It
  39  * extends ramfs by the ability to use swap and honor resource limits
  40  * which makes it a completely usable filesystem.
  41  */
  42
  43 #include <linux/xattr.h>
  44 #include <linux/exportfs.h>
  45 #include <linux/posix_acl.h>
  46 #include <linux/generic_acl.h>
  47 #include <linux/mman.h>
  48 #include <linux/string.h>
  49 #include <linux/slab.h>
  50 #include <linux/backing-dev.h>
  51 #include <linux/shmem_fs.h>
  52 #include <linux/writeback.h>
  53 #include <linux/blkdev.h>
  54 #include <linux/pagevec.h>
  55 #include <linux/percpu_counter.h>
  56 #include <linux/falloc.h>
  57 #include <linux/splice.h>
  58 #include <linux/security.h>
  59 #include <linux/swapops.h>
  60 #include <linux/mempolicy.h>
  61 #include <linux/namei.h>
  62 #include <linux/ctype.h>
  63 #include <linux/migrate.h>
  64 #include <linux/highmem.h>
  65 #include <linux/seq_file.h>
  66 #include <linux/magic.h>
  67
  68 #include <asm/uaccess.h>
  69 #include <asm/pgtable.h>
  70
  71 #define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
  72 #define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
  73
  74 /* Pretend that each entry is of this size in directory's i_size */
  75 #define BOGO_DIRENT_SIZE 20
  76
  77 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
  78 #define SHORT_SYMLINK_LEN 128
  79
  80 struct shmem_xattr {
  81         struct list_head list;  /* anchored by shmem_inode_info->xattr_list */
  82         char *name;             /* xattr name */
  83         size_t size;
  84         char value[0];
  85 };
  86
  87 /*
  88  * shmem_fallocate and shmem_writepage communicate via inode->i_private
  89  * (with i_mutex making sure that it has only one user at a time):
  90  * we would prefer not to enlarge the shmem inode just for that.
  91  */
  92 struct shmem_falloc {
  93         pgoff_t start;          /* start of range currently being fallocated */
  94         pgoff_t next;           /* the next page offset to be fallocated */
  95         pgoff_t nr_falloced;    /* how many new pages have been fallocated */
  96         pgoff_t nr_unswapped;   /* how often writepage refused to swap out */
  97 };
  98
  99 /* Flag allocation requirements to shmem_getpage */
 100 enum sgp_type {
 101         SGP_READ,       /* don't exceed i_size, don't allocate page */
 102         SGP_CACHE,      /* don't exceed i_size, may allocate page */
 103         SGP_DIRTY,      /* like SGP_CACHE, but set new page dirty */
 104         SGP_WRITE,      /* may exceed i_size, may allocate !Uptodate page */
 105         SGP_FALLOC,     /* like SGP_WRITE, but make existing page Uptodate */
 106 };
 107
 108 #ifdef CONFIG_TMPFS
 109 static unsigned long shmem_default_max_blocks(void)
 110 {
 111         return totalram_pages / 2;
 112 }
 113
 114 static unsigned long shmem_default_max_inodes(void)
 115 {
 116         return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
 117 }
 118 #endif
 119
 120 static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
 121 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 122                                 struct shmem_inode_info *info, pgoff_t index);
 123 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 124         struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
 125
 126 static inline int shmem_getpage(struct inode *inode, pgoff_t index,
 127         struct page **pagep, enum sgp_type sgp, int *fault_type)
 128 {
 129         return shmem_getpage_gfp(inode, index, pagep, sgp,
 130                         mapping_gfp_mask(inode->i_mapping), fault_type);
 131 }
 132
 133 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
 134 {
 135         return sb->s_fs_info;
 136 }
 137
 138 /*
 139  * shmem_file_setup pre-accounts the whole fixed size of a VM object,
 140  * for shared memory and for shared anonymous (/dev/zero) mappings
 141  * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
 142  * consistent with the pre-accounting of private mappings ...
 143  */
 144 static inline int shmem_acct_size(unsigned long flags, loff_t size)
 145 {
 146         return (flags & VM_NORESERVE) ?
 147                 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
 148 }
 149
 150 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
 151 {
 152         if (!(flags & VM_NORESERVE))
 153                 vm_unacct_memory(VM_ACCT(size));
 154 }
 155
 156 /*
 157  * ... whereas tmpfs objects are accounted incrementally as
 158  * pages are allocated, in order to allow huge sparse files.
 159  * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
 160  * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
 161  */
 162 static inline int shmem_acct_block(unsigned long flags)
 163 {
 164         return (flags & VM_NORESERVE) ?
 165                 security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0;
 166 }
 167
 168 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
 169 {
 170         if (flags & VM_NORESERVE)
 171                 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
 172 }
 173
 174 static const struct super_operations shmem_ops;
 175 static const struct address_space_operations shmem_aops;
 176 static const struct file_operations shmem_file_operations;
 177 static const struct inode_operations shmem_inode_operations;
 178 static const struct inode_operations shmem_dir_inode_operations;
 179 static const struct inode_operations shmem_special_inode_operations;
 180 static const struct vm_operations_struct shmem_vm_ops;
 181
 182 static struct backing_dev_info shmem_backing_dev_info  __read_mostly = {
 183         .ra_pages       = 0,    /* No readahead */
 184         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
 185 };
 186
 187 static LIST_HEAD(shmem_swaplist);
 188 static DEFINE_MUTEX(shmem_swaplist_mutex);
 189
 190 static int shmem_reserve_inode(struct super_block *sb)
 191 {
 192         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 193         if (sbinfo->max_inodes) {
 194                 spin_lock(&sbinfo->stat_lock);
 195                 if (!sbinfo->free_inodes) {
 196                         spin_unlock(&sbinfo->stat_lock);
 197                         return -ENOSPC;
 198                 }
 199                 sbinfo->free_inodes--;
 200                 spin_unlock(&sbinfo->stat_lock);
 201         }
 202         return 0;
 203 }
 204
 205 static void shmem_free_inode(struct super_block *sb)
 206 {
 207         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 208         if (sbinfo->max_inodes) {
 209                 spin_lock(&sbinfo->stat_lock);
 210                 sbinfo->free_inodes++;
 211                 spin_unlock(&sbinfo->stat_lock);
 212         }
 213 }
 214
 215 /**
 216  * shmem_recalc_inode - recalculate the block usage of an inode
 217  * @inode: inode to recalc
 218  *
 219  * We have to calculate the free blocks since the mm can drop
 220  * undirtied hole pages behind our back.
 221  *
 222  * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
 223  * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
 224  *
 225  * It has to be called with the spinlock held.
 226  */
 227 static void shmem_recalc_inode(struct inode *inode)
 228 {
 229         struct shmem_inode_info *info = SHMEM_I(inode);
 230         long freed;
 231
 232         freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
 233         if (freed > 0) {
 234                 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 235                 if (sbinfo->max_blocks)
 236                         percpu_counter_add(&sbinfo->used_blocks, -freed);
 237                 info->alloced -= freed;
 238                 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
 239                 shmem_unacct_blocks(info->flags, freed);
 240         }
 241 }
 242
 243 /*
 244  * Replace item expected in radix tree by a new item, while holding tree lock.
 245  */
 246 static int shmem_radix_tree_replace(struct address_space *mapping,
 247                         pgoff_t index, void *expected, void *replacement)
 248 {
 249         void **pslot;
 250         void *item = NULL;
 251
 252         VM_BUG_ON(!expected);
 253         pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
 254         if (pslot)
 255                 item = radix_tree_deref_slot_protected(pslot,
 256                                                         &mapping->tree_lock);
 257         if (item != expected)
 258                 return -ENOENT;
 259         if (replacement)
 260                 radix_tree_replace_slot(pslot, replacement);
 261         else
 262                 radix_tree_delete(&mapping->page_tree, index);
 263         return 0;
 264 }
 265
 266 /*
 267  * Like add_to_page_cache_locked, but error if expected item has gone.
 268  */
 269 static int shmem_add_to_page_cache(struct page *page,
 270                                    struct address_space *mapping,
 271                                    pgoff_t index, gfp_t gfp, void *expected)
 272 {
 273         int error = 0;
 274
 275         VM_BUG_ON(!PageLocked(page));
 276         VM_BUG_ON(!PageSwapBacked(page));
 277
 278         if (!expected)
 279                 error = radix_tree_preload(gfp & GFP_RECLAIM_MASK);
 280         if (!error) {
 281                 page_cache_get(page);
 282                 page->mapping = mapping;
 283                 page->index = index;
 284
 285                 spin_lock_irq(&mapping->tree_lock);
 286                 if (!expected)
 287                         error = radix_tree_insert(&mapping->page_tree,
 288                                                         index, page);
 289                 else
 290                         error = shmem_radix_tree_replace(mapping, index,
 291                                                         expected, page);
 292                 if (!error) {
 293                         mapping->nrpages++;
 294                         __inc_zone_page_state(page, NR_FILE_PAGES);
 295                         __inc_zone_page_state(page, NR_SHMEM);
 296                         spin_unlock_irq(&mapping->tree_lock);
 297                 } else {
 298                         page->mapping = NULL;
 299                         spin_unlock_irq(&mapping->tree_lock);
 300                         page_cache_release(page);
 301                 }
 302                 if (!expected)
 303                         radix_tree_preload_end();
 304         }
 305         if (error)
 306                 mem_cgroup_uncharge_cache_page(page);
 307         return error;
 308 }
 309
 310 /*
 311  * Like delete_from_page_cache, but substitutes swap for page.
 312  */
 313 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
 314 {
 315         struct address_space *mapping = page->mapping;
 316         int error;
 317
 318         spin_lock_irq(&mapping->tree_lock);
 319         error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
 320         page->mapping = NULL;
 321         mapping->nrpages--;
 322         __dec_zone_page_state(page, NR_FILE_PAGES);
 323         __dec_zone_page_state(page, NR_SHMEM);
 324         spin_unlock_irq(&mapping->tree_lock);
 325         page_cache_release(page);
 326         BUG_ON(error);
 327 }
 328
 329 /*
 330  * Like find_get_pages, but collecting swap entries as well as pages.
 331  */
 332 static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
 333                                         pgoff_t start, unsigned int nr_pages,
 334                                         struct page **pages, pgoff_t *indices)
 335 {
 336         unsigned int i;
 337         unsigned int ret;
 338         unsigned int nr_found;
 339
 340         rcu_read_lock();
 341 restart:
 342         nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
 343                                 (void ***)pages, indices, start, nr_pages);
 344         ret = 0;
 345         for (i = 0; i < nr_found; i++) {
 346                 struct page *page;
 347 repeat:
 348                 page = radix_tree_deref_slot((void **)pages[i]);
 349                 if (unlikely(!page))
 350                         continue;
 351                 if (radix_tree_exception(page)) {
 352                         if (radix_tree_deref_retry(page))
 353                                 goto restart;
 354                         /*
 355                          * Otherwise, we must be storing a swap entry
 356                          * here as an exceptional entry: so return it
 357                          * without attempting to raise page count.
 358                          */
 359                         goto export;
 360                 }
 361                 if (!page_cache_get_speculative(page))
 362                         goto repeat;
 363
 364                 /* Has the page moved? */
 365                 if (unlikely(page != *((void **)pages[i]))) {
 366                         page_cache_release(page);
 367                         goto repeat;
 368                 }
 369 export:
 370                 indices[ret] = indices[i];
 371                 pages[ret] = page;
 372                 ret++;
 373         }
 374         if (unlikely(!ret && nr_found))
 375                 goto restart;
 376         rcu_read_unlock();
 377         return ret;
 378 }
 379
 380 /*
 381  * Remove swap entry from radix tree, free the swap and its page cache.
 382  */
 383 static int shmem_free_swap(struct address_space *mapping,
 384                            pgoff_t index, void *radswap)
 385 {
 386         int error;
 387
 388         spin_lock_irq(&mapping->tree_lock);
 389         error = shmem_radix_tree_replace(mapping, index, radswap, NULL);
 390         spin_unlock_irq(&mapping->tree_lock);
 391         if (!error)
 392                 free_swap_and_cache(radix_to_swp_entry(radswap));
 393         return error;
 394 }
 395
 396 /*
 397  * Pagevec may contain swap entries, so shuffle up pages before releasing.
 398  */
 399 static void shmem_deswap_pagevec(struct pagevec *pvec)
 400 {
 401         int i, j;
 402
 403         for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
 404                 struct page *page = pvec->pages[i];
 405                 if (!radix_tree_exceptional_entry(page))
 406                         pvec->pages[j++] = page;
 407         }
 408         pvec->nr = j;
 409 }
 410
 411 /*
 412  * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
 413  */
 414 void shmem_unlock_mapping(struct address_space *mapping)
 415 {
 416         struct pagevec pvec;
 417         pgoff_t indices[PAGEVEC_SIZE];
 418         pgoff_t index = 0;
 419
 420         pagevec_init(&pvec, 0);
 421         /*
 422          * Minor point, but we might as well stop if someone else SHM_LOCKs it.
 423          */
 424         while (!mapping_unevictable(mapping)) {
 425                 /*
 426                  * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
 427                  * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
 428                  */
 429                 pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
 430                                         PAGEVEC_SIZE, pvec.pages, indices);
 431                 if (!pvec.nr)
 432                         break;
 433                 index = indices[pvec.nr - 1] + 1;
 434                 shmem_deswap_pagevec(&pvec);
 435                 check_move_unevictable_pages(pvec.pages, pvec.nr);
 436                 pagevec_release(&pvec);
 437                 cond_resched();
 438         }
 439 }
 440
 441 /*
 442  * Remove range of pages and swap entries from radix tree, and free them.
 443  * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
 444  */
 445 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 446                                                                  bool unfalloc)
 447 {
 448         struct address_space *mapping = inode->i_mapping;
 449         struct shmem_inode_info *info = SHMEM_I(inode);
 450         pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 451         pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
 452         unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
 453         unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
 454         struct pagevec pvec;
 455         pgoff_t indices[PAGEVEC_SIZE];
 456         long nr_swaps_freed = 0;
 457         pgoff_t index;
 458         int i;
 459
 460         if (lend == -1)
 461                 end = -1;       /* unsigned, so actually very big */
 462
 463         pagevec_init(&pvec, 0);
 464         index = start;
 465         while (index < end) {
 466                 pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
 467                                 min(end - index, (pgoff_t)PAGEVEC_SIZE),
 468                                                         pvec.pages, indices);
 469                 if (!pvec.nr)
 470                         break;
 471                 mem_cgroup_uncharge_start();
 472                 for (i = 0; i < pagevec_count(&pvec); i++) {
 473                         struct page *page = pvec.pages[i];
 474
 475                         index = indices[i];
 476                         if (index >= end)
 477                                 break;
 478
 479                         if (radix_tree_exceptional_entry(page)) {
 480                                 if (unfalloc)
 481                                         continue;
 482                                 nr_swaps_freed += !shmem_free_swap(mapping,
 483                                                                 index, page);
 484                                 continue;
 485                         }
 486
 487                         if (!trylock_page(page))
 488                                 continue;
 489                         if (!unfalloc || !PageUptodate(page)) {
 490                                 if (page->mapping == mapping) {
 491                                         VM_BUG_ON(PageWriteback(page));
 492                                         truncate_inode_page(mapping, page);
 493                                 }
 494                         }
 495                         unlock_page(page);
 496                 }
 497                 shmem_deswap_pagevec(&pvec);
 498                 pagevec_release(&pvec);
 499                 mem_cgroup_uncharge_end();
 500                 cond_resched();
 501                 index++;
 502         }
 503
 504         if (partial_start) {
 505                 struct page *page = NULL;
 506                 shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
 507                 if (page) {
 508                         unsigned int top = PAGE_CACHE_SIZE;
 509                         if (start > end) {
 510                                 top = partial_end;
 511                                 partial_end = 0;
 512                         }
 513                         zero_user_segment(page, partial_start, top);
 514                         set_page_dirty(page);
 515                         unlock_page(page);
 516                         page_cache_release(page);
 517                 }
 518         }
 519         if (partial_end) {
 520                 struct page *page = NULL;
 521                 shmem_getpage(inode, end, &page, SGP_READ, NULL);
 522                 if (page) {
 523                         zero_user_segment(page, 0, partial_end);
 524                         set_page_dirty(page);
 525                         unlock_page(page);
 526                         page_cache_release(page);
 527                 }
 528         }
 529         if (start >= end)
 530                 return;
 531
 532         index = start;
 533         for ( ; ; ) {
 534                 cond_resched();
 535                 pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
 536                                 min(end - index, (pgoff_t)PAGEVEC_SIZE),
 537                                                         pvec.pages, indices);
 538                 if (!pvec.nr) {
 539                         if (index == start || unfalloc)
 540                                 break;
 541                         index = start;
 542                         continue;
 543                 }
 544                 if ((index == start || unfalloc) && indices[0] >= end) {
 545                         shmem_deswap_pagevec(&pvec);
 546                         pagevec_release(&pvec);
 547                         break;
 548                 }
 549                 mem_cgroup_uncharge_start();
 550                 for (i = 0; i < pagevec_count(&pvec); i++) {
 551                         struct page *page = pvec.pages[i];
 552
 553                         index = indices[i];
 554                         if (index >= end)
 555                                 break;
 556
 557                         if (radix_tree_exceptional_entry(page)) {
 558                                 if (unfalloc)
 559                                         continue;
 560                                 nr_swaps_freed += !shmem_free_swap(mapping,
 561                                                                 index, page);
 562                                 continue;
 563                         }
 564
 565                         lock_page(page);
 566                         if (!unfalloc || !PageUptodate(page)) {
 567                                 if (page->mapping == mapping) {
 568                                         VM_BUG_ON(PageWriteback(page));
 569                                         truncate_inode_page(mapping, page);
 570                                 }
 571                         }
 572                         unlock_page(page);
 573                 }
 574                 shmem_deswap_pagevec(&pvec);
 575                 pagevec_release(&pvec);
 576                 mem_cgroup_uncharge_end();
 577                 index++;
 578         }
 579
 580         spin_lock(&info->lock);
 581         info->swapped -= nr_swaps_freed;
 582         shmem_recalc_inode(inode);
 583         spin_unlock(&info->lock);
 584 }
 585
 586 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
 587 {
 588         shmem_undo_range(inode, lstart, lend, false);
 589         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
 590 }
 591 EXPORT_SYMBOL_GPL(shmem_truncate_range);
 592
 593 static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 594 {
 595         struct inode *inode = dentry->d_inode;
 596         int error;
 597
 598         error = inode_change_ok(inode, attr);
 599         if (error)
 600                 return error;
 601
 602         if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
 603                 loff_t oldsize = inode->i_size;
 604                 loff_t newsize = attr->ia_size;
 605
 606                 if (newsize != oldsize) {
 607                         i_size_write(inode, newsize);
 608                         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
 609                 }
 610                 if (newsize < oldsize) {
 611                         loff_t holebegin = round_up(newsize, PAGE_SIZE);
 612                         unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
 613                         shmem_truncate_range(inode, newsize, (loff_t)-1);
 614                         /* unmap again to remove racily COWed private pages */
 615                         unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
 616                 }
 617         }
 618
 619         setattr_copy(inode, attr);
 620 #ifdef CONFIG_TMPFS_POSIX_ACL
 621         if (attr->ia_valid & ATTR_MODE)
 622                 error = generic_acl_chmod(inode);
 623 #endif
 624         return error;
 625 }
 626
 627 static void shmem_evict_inode(struct inode *inode)
 628 {
 629         struct shmem_inode_info *info = SHMEM_I(inode);
 630         struct shmem_xattr *xattr, *nxattr;
 631
 632         if (inode->i_mapping->a_ops == &shmem_aops) {
 633                 shmem_unacct_size(info->flags, inode->i_size);
 634                 inode->i_size = 0;
 635                 shmem_truncate_range(inode, 0, (loff_t)-1);
 636                 if (!list_empty(&info->swaplist)) {
 637                         mutex_lock(&shmem_swaplist_mutex);
 638                         list_del_init(&info->swaplist);
 639                         mutex_unlock(&shmem_swaplist_mutex);
 640                 }
 641         } else
 642                 kfree(info->symlink);
 643
 644         list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) {
 645                 kfree(xattr->name);
 646                 kfree(xattr);
 647         }
 648         BUG_ON(inode->i_blocks);
 649         shmem_free_inode(inode->i_sb);
 650         clear_inode(inode);
 651 }
 652
 653 /*
 654  * If swap found in inode, free it and move page from swapcache to filecache.
 655  */
 656 static int shmem_unuse_inode(struct shmem_inode_info *info,
 657                              swp_entry_t swap, struct page **pagep)
 658 {
 659         struct address_space *mapping = info->vfs_inode.i_mapping;
 660         void *radswap;
 661         pgoff_t index;
 662         gfp_t gfp;
 663         int error = 0;
 664
 665         radswap = swp_to_radix_entry(swap);
 666         index = radix_tree_locate_item(&mapping->page_tree, radswap);
 667         if (index == -1)
 668                 return 0;
 669
 670         /*
 671          * Move _head_ to start search for next from here.
 672          * But be careful: shmem_evict_inode checks list_empty without taking
 673          * mutex, and there's an instant in list_move_tail when info->swaplist
 674          * would appear empty, if it were the only one on shmem_swaplist.
 675          */
 676         if (shmem_swaplist.next != &info->swaplist)
 677                 list_move_tail(&shmem_swaplist, &info->swaplist);
 678
 679         gfp = mapping_gfp_mask(mapping);
 680         if (shmem_should_replace_page(*pagep, gfp)) {
 681                 mutex_unlock(&shmem_swaplist_mutex);
 682                 error = shmem_replace_page(pagep, gfp, info, index);
 683                 mutex_lock(&shmem_swaplist_mutex);
 684                 /*
 685                  * We needed to drop mutex to make that restrictive page
 686                  * allocation; but the inode might already be freed by now,
 687                  * and we cannot refer to inode or mapping or info to check.
 688                  * However, we do hold page lock on the PageSwapCache page,
 689                  * so can check if that still has our reference remaining.
 690                  */
 691                 if (!page_swapcount(*pagep))
 692                         error = -ENOENT;
 693         }
 694
 695         /*
 696          * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
 697          * but also to hold up shmem_evict_inode(): so inode cannot be freed
 698          * beneath us (pagelock doesn't help until the page is in pagecache).
 699          */
 700         if (!error)
 701                 error = shmem_add_to_page_cache(*pagep, mapping, index,
 702                                                 GFP_NOWAIT, radswap);
 703         if (error != -ENOMEM) {
 704                 /*
 705                  * Truncation and eviction use free_swap_and_cache(), which
 706                  * only does trylock page: if we raced, best clean up here.
 707                  */
 708                 delete_from_swap_cache(*pagep);
 709                 set_page_dirty(*pagep);
 710                 if (!error) {
 711                         spin_lock(&info->lock);
 712                         info->swapped--;
 713                         spin_unlock(&info->lock);
 714                         swap_free(swap);
 715                 }
 716                 error = 1;      /* not an error, but entry was found */
 717         }
 718         return error;
 719 }
 720
 721 /*
 722  * Search through swapped inodes to find and replace swap by page.
 723  */
 724 int shmem_unuse(swp_entry_t swap, struct page *page)
 725 {
 726         struct list_head *this, *next;
 727         struct shmem_inode_info *info;
 728         int found = 0;
 729         int error = 0;
 730
 731         /*
 732          * There's a faint possibility that swap page was replaced before
 733          * caller locked it: it will come back later with the right page.
 734          */
 735         if (unlikely(!PageSwapCache(page)))
 736                 goto out;
 737
 738         /*
 739          * Charge page using GFP_KERNEL while we can wait, before taking
 740          * the shmem_swaplist_mutex which might hold up shmem_writepage().
 741          * Charged back to the user (not to caller) when swap account is used.
 742          */
 743         error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
 744         if (error)
 745                 goto out;
 746         /* No radix_tree_preload: swap entry keeps a place for page in tree */
 747
 748         mutex_lock(&shmem_swaplist_mutex);
 749         list_for_each_safe(this, next, &shmem_swaplist) {
 750                 info = list_entry(this, struct shmem_inode_info, swaplist);
 751                 if (info->swapped)
 752                         found = shmem_unuse_inode(info, swap, &page);
 753                 else
 754                         list_del_init(&info->swaplist);
 755                 cond_resched();
 756                 if (found)
 757                         break;
 758         }
 759         mutex_unlock(&shmem_swaplist_mutex);
 760
 761         if (found < 0)
 762                 error = found;
 763 out:
 764         unlock_page(page);
 765         page_cache_release(page);
 766         return error;
 767 }
 768
 769 /*
 770  * Move the page from the page cache to the swap cache.
 771  */
 772 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 773 {
 774         struct shmem_inode_info *info;
 775         struct address_space *mapping;
 776         struct inode *inode;
 777         swp_entry_t swap;
 778         pgoff_t index;
 779
 780         BUG_ON(!PageLocked(page));
 781         mapping = page->mapping;
 782         index = page->index;
 783         inode = mapping->host;
 784         info = SHMEM_I(inode);
 785         if (info->flags & VM_LOCKED)
 786                 goto redirty;
 787         if (!total_swap_pages)
 788                 goto redirty;
 789
 790         /*
 791          * shmem_backing_dev_info's capabilities prevent regular writeback or
 792          * sync from ever calling shmem_writepage; but a stacking filesystem
 793          * might use ->writepage of its underlying filesystem, in which case
 794          * tmpfs should write out to swap only in response to memory pressure,
 795          * and not for the writeback threads or sync.
 796          */
 797         if (!wbc->for_reclaim) {
 798                 WARN_ON_ONCE(1);        /* Still happens? Tell us about it! */
 799                 goto redirty;
 800         }
 801
 802         /*
 803          * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
 804          * value into swapfile.c, the only way we can correctly account for a
 805          * fallocated page arriving here is now to initialize it and write it.
 806          *
 807          * That's okay for a page already fallocated earlier, but if we have
 808          * not yet completed the fallocation, then (a) we want to keep track
 809          * of this page in case we have to undo it, and (b) it may not be a
 810          * good idea to continue anyway, once we're pushing into swap.  So
 811          * reactivate the page, and let shmem_fallocate() quit when too many.
 812          */
 813         if (!PageUptodate(page)) {
 814                 if (inode->i_private) {
 815                         struct shmem_falloc *shmem_falloc;
 816                         spin_lock(&inode->i_lock);
 817                         shmem_falloc = inode->i_private;
 818                         if (shmem_falloc &&
 819                             index >= shmem_falloc->start &&
 820                             index < shmem_falloc->next)
 821                                 shmem_falloc->nr_unswapped++;
 822                         else
 823                                 shmem_falloc = NULL;
 824                         spin_unlock(&inode->i_lock);
 825                         if (shmem_falloc)
 826                                 goto redirty;
 827                 }
 828                 clear_highpage(page);
 829                 flush_dcache_page(page);
 830                 SetPageUptodate(page);
 831         }
 832
 833         swap = get_swap_page();
 834         if (!swap.val)
 835                 goto redirty;
 836
 837         /*
 838          * Add inode to shmem_unuse()'s list of swapped-out inodes,
 839          * if it's not already there.  Do it now before the page is
 840          * moved to swap cache, when its pagelock no longer protects
 841          * the inode from eviction.  But don't unlock the mutex until
 842          * we've incremented swapped, because shmem_unuse_inode() will
 843          * prune a !swapped inode from the swaplist under this mutex.
 844          */
 845         mutex_lock(&shmem_swaplist_mutex);
 846         if (list_empty(&info->swaplist))
 847                 list_add_tail(&info->swaplist, &shmem_swaplist);
 848
 849         if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
 850                 swap_shmem_alloc(swap);
 851                 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
 852
 853                 spin_lock(&info->lock);
 854                 info->swapped++;
 855                 shmem_recalc_inode(inode);
 856                 spin_unlock(&info->lock);
 857
 858                 mutex_unlock(&shmem_swaplist_mutex);
 859                 BUG_ON(page_mapped(page));
 860                 swap_writepage(page, wbc);
 861                 return 0;
 862         }
 863
 864         mutex_unlock(&shmem_swaplist_mutex);
 865         swapcache_free(swap, NULL);
 866 redirty:
 867         set_page_dirty(page);
 868         if (wbc->for_reclaim)
 869                 return AOP_WRITEPAGE_ACTIVATE;  /* Return with page locked */
 870         unlock_page(page);
 871         return 0;
 872 }
 873
 874 #ifdef CONFIG_NUMA
 875 #ifdef CONFIG_TMPFS
 876 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
 877 {
 878         char buffer[64];
 879
 880         if (!mpol || mpol->mode == MPOL_DEFAULT)
 881                 return;         /* show nothing */
 882
 883         mpol_to_str(buffer, sizeof(buffer), mpol, 1);
 884
 885         seq_printf(seq, ",mpol=%s", buffer);
 886 }
 887
 888 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
 889 {
 890         struct mempolicy *mpol = NULL;
 891         if (sbinfo->mpol) {
 892                 spin_lock(&sbinfo->stat_lock);  /* prevent replace/use races */
 893                 mpol = sbinfo->mpol;
 894                 mpol_get(mpol);
 895                 spin_unlock(&sbinfo->stat_lock);
 896         }
 897         return mpol;
 898 }
 899 #endif /* CONFIG_TMPFS */
 900
 901 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
 902                         struct shmem_inode_info *info, pgoff_t index)
 903 {
 904         struct mempolicy mpol, *spol;
 905         struct vm_area_struct pvma;
 906
 907         spol = mpol_cond_copy(&mpol,
 908                         mpol_shared_policy_lookup(&info->policy, index));
 909
 910         /* Create a pseudo vma that just contains the policy */
 911         pvma.vm_start = 0;
 912         pvma.vm_pgoff = index;
 913         pvma.vm_ops = NULL;
 914         pvma.vm_policy = spol;
 915         return swapin_readahead(swap, gfp, &pvma, 0);
 916 }
 917
 918 static struct page *shmem_alloc_page(gfp_t gfp,
 919                         struct shmem_inode_info *info, pgoff_t index)
 920 {
 921         struct vm_area_struct pvma;
 922
 923         /* Create a pseudo vma that just contains the policy */
 924         pvma.vm_start = 0;
 925         pvma.vm_pgoff = index;
 926         pvma.vm_ops = NULL;
 927         pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
 928
 929         /*
 930          * alloc_page_vma() will drop the shared policy reference
 931          */
 932         return alloc_page_vma(gfp, &pvma, 0);
 933 }
 934 #else /* !CONFIG_NUMA */
 935 #ifdef CONFIG_TMPFS
 936 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
 937 {
 938 }
 939 #endif /* CONFIG_TMPFS */
 940
 941 static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
 942                         struct shmem_inode_info *info, pgoff_t index)
 943 {
 944         return swapin_readahead(swap, gfp, NULL, 0);
 945 }
 946
 947 static inline struct page *shmem_alloc_page(gfp_t gfp,
 948                         struct shmem_inode_info *info, pgoff_t index)
 949 {
 950         return alloc_page(gfp);
 951 }
 952 #endif /* CONFIG_NUMA */
 953
 954 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
 955 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
 956 {
 957         return NULL;
 958 }
 959 #endif
 960
 961 /*
 962  * When a page is moved from swapcache to shmem filecache (either by the
 963  * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
 964  * shmem_unuse_inode()), it may have been read in earlier from swap, in
 965  * ignorance of the mapping it belongs to.  If that mapping has special
 966  * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
 967  * we may need to copy to a suitable page before moving to filecache.
 968  *
 969  * In a future release, this may well be extended to respect cpuset and
 970  * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
 971  * but for now it is a simple matter of zone.
 972  */
 973 static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
 974 {
 975         return page_zonenum(page) > gfp_zone(gfp);
 976 }
 977
 978 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 979                                 struct shmem_inode_info *info, pgoff_t index)
 980 {
 981         struct page *oldpage, *newpage;
 982         struct address_space *swap_mapping;
 983         pgoff_t swap_index;
 984         int error;
 985
 986         oldpage = *pagep;
 987         swap_index = page_private(oldpage);
 988         swap_mapping = page_mapping(oldpage);
 989
 990         /*
 991          * We have arrived here because our zones are constrained, so don't
 992          * limit chance of success by further cpuset and node constraints.
 993          */
 994         gfp &= ~GFP_CONSTRAINT_MASK;
 995         newpage = shmem_alloc_page(gfp, info, index);
 996         if (!newpage)
 997                 return -ENOMEM;
 998         VM_BUG_ON(shmem_should_replace_page(newpage, gfp));
 999
1000         *pagep = newpage;
1001         page_cache_get(newpage);
1002         copy_highpage(newpage, oldpage);
1003
1004         VM_BUG_ON(!PageLocked(oldpage));
1005         __set_page_locked(newpage);
1006         VM_BUG_ON(!PageUptodate(oldpage));
1007         SetPageUptodate(newpage);
1008         VM_BUG_ON(!PageSwapBacked(oldpage));
1009         SetPageSwapBacked(newpage);
1010         VM_BUG_ON(!swap_index);
1011         set_page_private(newpage, swap_index);
1012         VM_BUG_ON(!PageSwapCache(oldpage));
1013         SetPageSwapCache(newpage);
1014
1015         /*
1016          * Our caller will very soon move newpage out of swapcache, but it's
1017          * a nice clean interface for us to replace oldpage by newpage there.
1018          */
1019         spin_lock_irq(&swap_mapping->tree_lock);
1020         error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
1021                                                                    newpage);
1022         __inc_zone_page_state(newpage, NR_FILE_PAGES);
1023         __dec_zone_page_state(oldpage, NR_FILE_PAGES);
1024         spin_unlock_irq(&swap_mapping->tree_lock);
1025         BUG_ON(error);
1026
1027         mem_cgroup_replace_page_cache(oldpage, newpage);
1028         lru_cache_add_anon(newpage);
1029
1030         ClearPageSwapCache(oldpage);
1031         set_page_private(oldpage, 0);
1032
1033         unlock_page(oldpage);
1034         page_cache_release(oldpage);
1035         page_cache_release(oldpage);
1036         return 0;
1037 }
1038
1039 /*
1040  * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1041  *
1042  * If we allocate a new one we do not mark it dirty. That's up to the
1043  * vm. If we swap it in we mark it dirty since we also free the swap
1044  * entry since a page cannot live in both the swap and page cache
1045  */
1046 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1047         struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
1048 {
1049         struct address_space *mapping = inode->i_mapping;
1050         struct shmem_inode_info *info;
1051         struct shmem_sb_info *sbinfo;
1052         struct page *page;
1053         swp_entry_t swap;
1054         int error;
1055         int once = 0;
1056         int alloced = 0;
1057
1058         if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
1059                 return -EFBIG;
1060 repeat:
1061         swap.val = 0;
1062         page = find_lock_page(mapping, index);
1063         if (radix_tree_exceptional_entry(page)) {
1064                 swap = radix_to_swp_entry(page);
1065                 page = NULL;
1066         }
1067
1068         if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
1069             ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
1070                 error = -EINVAL;
1071                 goto failed;
1072         }
1073
1074         /* fallocated page? */
1075         if (page && !PageUptodate(page)) {
1076                 if (sgp != SGP_READ)
1077                         goto clear;
1078                 unlock_page(page);
1079                 page_cache_release(page);
1080                 page = NULL;
1081         }
1082         if (page || (sgp == SGP_READ && !swap.val)) {
1083                 *pagep = page;
1084                 return 0;
1085         }
1086
1087         /*
1088          * Fast cache lookup did not find it:
1089          * bring it back from swap or allocate.
1090          */
1091         info = SHMEM_I(inode);
1092         sbinfo = SHMEM_SB(inode->i_sb);
1093
1094         if (swap.val) {
1095                 /* Look it up and read it in.. */
1096                 page = lookup_swap_cache(swap);
1097                 if (!page) {
1098                         /* here we actually do the io */
1099                         if (fault_type)
1100                                 *fault_type |= VM_FAULT_MAJOR;
1101                         page = shmem_swapin(swap, gfp, info, index);
1102                         if (!page) {
1103                                 error = -ENOMEM;
1104                                 goto failed;
1105                         }
1106                 }
1107
1108                 /* We have to do this with page locked to prevent races */
1109                 lock_page(page);
1110                 if (!PageSwapCache(page) || page->mapping) {
1111                         error = -EEXIST;        /* try again */
1112                         goto failed;
1113                 }
1114                 if (!PageUptodate(page)) {
1115                         error = -EIO;
1116                         goto failed;
1117                 }
1118                 wait_on_page_writeback(page);
1119
1120                 if (shmem_should_replace_page(page, gfp)) {
1121                         error = shmem_replace_page(&page, gfp, info, index);
1122                         if (error)
1123                                 goto failed;
1124                 }
1125
1126                 error = mem_cgroup_cache_charge(page, current->mm,
1127                                                 gfp & GFP_RECLAIM_MASK);
1128                 if (!error)
1129                         error = shmem_add_to_page_cache(page, mapping, index,
1130                                                 gfp, swp_to_radix_entry(swap));
1131                 if (error)
1132                         goto failed;
1133
1134                 spin_lock(&info->lock);
1135                 info->swapped--;
1136                 shmem_recalc_inode(inode);
1137                 spin_unlock(&info->lock);
1138
1139                 delete_from_swap_cache(page);
1140                 set_page_dirty(page);
1141                 swap_free(swap);
1142
1143         } else {
1144                 if (shmem_acct_block(info->flags)) {
1145                         error = -ENOSPC;
1146                         goto failed;
1147                 }
1148                 if (sbinfo->max_blocks) {
1149                         if (percpu_counter_compare(&sbinfo->used_blocks,
1150                                                 sbinfo->max_blocks) >= 0) {
1151                                 error = -ENOSPC;
1152                                 goto unacct;
1153                         }
1154                         percpu_counter_inc(&sbinfo->used_blocks);
1155                 }
1156
1157                 page = shmem_alloc_page(gfp, info, index);
1158                 if (!page) {
1159                         error = -ENOMEM;
1160                         goto decused;
1161                 }
1162
1163                 SetPageSwapBacked(page);
1164                 __set_page_locked(page);
1165                 error = mem_cgroup_cache_charge(page, current->mm,
1166                                                 gfp & GFP_RECLAIM_MASK);
1167                 if (!error)
1168                         error = shmem_add_to_page_cache(page, mapping, index,
1169                                                 gfp, NULL);
1170                 if (error)
1171                         goto decused;
1172                 lru_cache_add_anon(page);
1173
1174                 spin_lock(&info->lock);
1175                 info->alloced++;
1176                 inode->i_blocks += BLOCKS_PER_PAGE;
1177                 shmem_recalc_inode(inode);
1178                 spin_unlock(&info->lock);
1179                 alloced = true;
1180
1181                 /*
1182                  * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1183                  */
1184                 if (sgp == SGP_FALLOC)
1185                         sgp = SGP_WRITE;
1186 clear:
1187                 /*
1188                  * Let SGP_WRITE caller clear ends if write does not fill page;
1189                  * but SGP_FALLOC on a page fallocated earlier must initialize
1190                  * it now, lest undo on failure cancel our earlier guarantee.
1191                  */
1192                 if (sgp != SGP_WRITE) {
1193                         clear_highpage(page);
1194                         flush_dcache_page(page);
1195                         SetPageUptodate(page);
1196                 }
1197                 if (sgp == SGP_DIRTY)
1198                         set_page_dirty(page);
1199         }
1200
1201         /* Perhaps the file has been truncated since we checked */
1202         if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
1203             ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
1204                 error = -EINVAL;
1205                 if (alloced)
1206                         goto trunc;
1207                 else
1208                         goto failed;
1209         }
1210         *pagep = page;
1211         return 0;
1212
1213         /*
1214          * Error recovery.
1215          */
1216 trunc:
1217         info = SHMEM_I(inode);
1218         ClearPageDirty(page);
1219         delete_from_page_cache(page);
1220         spin_lock(&info->lock);
1221         info->alloced--;
1222         inode->i_blocks -= BLOCKS_PER_PAGE;
1223         spin_unlock(&info->lock);
1224 decused:
1225         sbinfo = SHMEM_SB(inode->i_sb);
1226         if (sbinfo->max_blocks)
1227                 percpu_counter_add(&sbinfo->used_blocks, -1);
1228 unacct:
1229         shmem_unacct_blocks(info->flags, 1);
1230 failed:
1231         if (swap.val && error != -EINVAL) {
1232                 struct page *test = find_get_page(mapping, index);
1233                 if (test && !radix_tree_exceptional_entry(test))
1234                         page_cache_release(test);
1235                 /* Have another try if the entry has changed */
1236                 if (test != swp_to_radix_entry(swap))
1237                         error = -EEXIST;
1238         }
1239         if (page) {
1240                 unlock_page(page);
1241                 page_cache_release(page);
1242         }
1243         if (error == -ENOSPC && !once++) {
1244                 info = SHMEM_I(inode);
1245                 spin_lock(&info->lock);
1246                 shmem_recalc_inode(inode);
1247                 spin_unlock(&info->lock);
1248                 goto repeat;
1249         }
1250         if (error == -EEXIST)
1251                 goto repeat;
1252         return error;
1253 }
1254
1255 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1256 {
1257         struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1258         int error;
1259         int ret = VM_FAULT_LOCKED;
1260
1261         error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
1262         if (error)
1263                 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1264
1265         if (ret & VM_FAULT_MAJOR) {
1266                 count_vm_event(PGMAJFAULT);
1267                 mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
1268         }
1269         return ret;
1270 }
1271
1272 #ifdef CONFIG_NUMA
1273 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
1274 {
1275         struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1276         return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
1277 }
1278
1279 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1280                                           unsigned long addr)
1281 {
1282         struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1283         pgoff_t index;
1284
1285         index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1286         return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
1287 }
1288 #endif
1289
1290 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1291 {
1292         struct inode *inode = file->f_path.dentry->d_inode;
1293         struct shmem_inode_info *info = SHMEM_I(inode);
1294         int retval = -ENOMEM;
1295
1296         spin_lock(&info->lock);
1297         if (lock && !(info->flags & VM_LOCKED)) {
1298                 if (!user_shm_lock(inode->i_size, user))
1299                         goto out_nomem;
1300                 info->flags |= VM_LOCKED;
1301                 mapping_set_unevictable(file->f_mapping);
1302         }
1303         if (!lock && (info->flags & VM_LOCKED) && user) {
1304                 user_shm_unlock(inode->i_size, user);
1305                 info->flags &= ~VM_LOCKED;
1306                 mapping_clear_unevictable(file->f_mapping);
1307         }
1308         retval = 0;
1309
1310 out_nomem:
1311         spin_unlock(&info->lock);
1312         return retval;
1313 }
1314
1315 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1316 {
1317         file_accessed(file);
1318         vma->vm_ops = &shmem_vm_ops;
1319         vma->vm_flags |= VM_CAN_NONLINEAR;
1320         return 0;
1321 }
1322
1323 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1324                                      umode_t mode, dev_t dev, unsigned long flags)
1325 {
1326         struct inode *inode;
1327         struct shmem_inode_info *info;
1328         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1329
1330         if (shmem_reserve_inode(sb))
1331                 return NULL;
1332
1333         inode = new_inode(sb);
1334         if (inode) {
1335                 inode->i_ino = get_next_ino();
1336                 inode_init_owner(inode, dir, mode);
1337                 inode->i_blocks = 0;
1338                 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1339                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1340                 inode->i_generation = get_seconds();
1341                 info = SHMEM_I(inode);
1342                 memset(info, 0, (char *)inode - (char *)info);
1343                 spin_lock_init(&info->lock);
1344                 info->flags = flags & VM_NORESERVE;
1345                 INIT_LIST_HEAD(&info->swaplist);
1346                 INIT_LIST_HEAD(&info->xattr_list);
1347                 cache_no_acl(inode);
1348
1349                 switch (mode & S_IFMT) {
1350                 default:
1351                         inode->i_op = &shmem_special_inode_operations;
1352                         init_special_inode(inode, mode, dev);
1353                         break;
1354                 case S_IFREG:
1355                         inode->i_mapping->a_ops = &shmem_aops;
1356                         inode->i_op = &shmem_inode_operations;
1357                         inode->i_fop = &shmem_file_operations;
1358                         mpol_shared_policy_init(&info->policy,
1359                                                  shmem_get_sbmpol(sbinfo));
1360                         break;
1361                 case S_IFDIR:
1362                         inc_nlink(inode);
1363                         /* Some things misbehave if size == 0 on a directory */
1364                         inode->i_size = 2 * BOGO_DIRENT_SIZE;
1365                         inode->i_op = &shmem_dir_inode_operations;
1366                         inode->i_fop = &simple_dir_operations;
1367                         break;
1368                 case S_IFLNK:
1369                         /*
1370                          * Must not load anything in the rbtree,
1371                          * mpol_free_shared_policy will not be called.
1372                          */
1373                         mpol_shared_policy_init(&info->policy, NULL);
1374                         break;
1375                 }
1376         } else
1377                 shmem_free_inode(sb);
1378         return inode;
1379 }
1380
1381 #ifdef CONFIG_TMPFS
1382 static const struct inode_operations shmem_symlink_inode_operations;
1383 static const struct inode_operations shmem_short_symlink_operations;
1384
1385 #ifdef CONFIG_TMPFS_XATTR
1386 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
1387 #else
1388 #define shmem_initxattrs NULL
1389 #endif
1390
1391 static int
1392 shmem_write_begin(struct file *file, struct address_space *mapping,
1393                         loff_t pos, unsigned len, unsigned flags,
1394                         struct page **pagep, void **fsdata)
1395 {
1396         struct inode *inode = mapping->host;
1397         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1398         return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1399 }
1400
1401 static int
1402 shmem_write_end(struct file *file, struct address_space *mapping,
1403                         loff_t pos, unsigned len, unsigned copied,
1404                         struct page *page, void *fsdata)
1405 {
1406         struct inode *inode = mapping->host;
1407
1408         if (pos + copied > inode->i_size)
1409                 i_size_write(inode, pos + copied);
1410
1411         if (!PageUptodate(page)) {
1412                 if (copied < PAGE_CACHE_SIZE) {
1413                         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1414                         zero_user_segments(page, 0, from,
1415                                         from + copied, PAGE_CACHE_SIZE);
1416                 }
1417                 SetPageUptodate(page);
1418         }
1419         set_page_dirty(page);
1420         unlock_page(page);
1421         page_cache_release(page);
1422
1423         return copied;
1424 }
1425
1426 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1427 {
1428         struct inode *inode = filp->f_path.dentry->d_inode;
1429         struct address_space *mapping = inode->i_mapping;
1430         pgoff_t index;
1431         unsigned long offset;
1432         enum sgp_type sgp = SGP_READ;
1433
1434         /*
1435          * Might this read be for a stacking filesystem?  Then when reading
1436          * holes of a sparse file, we actually need to allocate those pages,
1437          * and even mark them dirty, so it cannot exceed the max_blocks limit.
1438          */
1439         if (segment_eq(get_fs(), KERNEL_DS))
1440                 sgp = SGP_DIRTY;
1441
1442         index = *ppos >> PAGE_CACHE_SHIFT;
1443         offset = *ppos & ~PAGE_CACHE_MASK;
1444
1445         for (;;) {
1446                 struct page *page = NULL;
1447                 pgoff_t end_index;
1448                 unsigned long nr, ret;
1449                 loff_t i_size = i_size_read(inode);
1450
1451                 end_index = i_size >> PAGE_CACHE_SHIFT;
1452                 if (index > end_index)
1453                         break;
1454                 if (index == end_index) {
1455                         nr = i_size & ~PAGE_CACHE_MASK;
1456                         if (nr <= offset)
1457                                 break;
1458                 }
1459
1460                 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
1461                 if (desc->error) {
1462                         if (desc->error == -EINVAL)
1463                                 desc->error = 0;
1464                         break;
1465                 }
1466                 if (page)
1467                         unlock_page(page);
1468
1469                 /*
1470                  * We must evaluate after, since reads (unlike writes)
1471                  * are called without i_mutex protection against truncate
1472                  */
1473                 nr = PAGE_CACHE_SIZE;
1474                 i_size = i_size_read(inode);
1475                 end_index = i_size >> PAGE_CACHE_SHIFT;
1476                 if (index == end_index) {
1477                         nr = i_size & ~PAGE_CACHE_MASK;
1478                         if (nr <= offset) {
1479                                 if (page)
1480                                         page_cache_release(page);
1481                                 break;
1482                         }
1483                 }
1484                 nr -= offset;
1485
1486                 if (page) {
1487                         /*
1488                          * If users can be writing to this page using arbitrary
1489                          * virtual addresses, take care about potential aliasing
1490                          * before reading the page on the kernel side.
1491                          */
1492                         if (mapping_writably_mapped(mapping))
1493                                 flush_dcache_page(page);
1494                         /*
1495                          * Mark the page accessed if we read the beginning.
1496                          */
1497                         if (!offset)
1498                                 mark_page_accessed(page);
1499                 } else {
1500                         page = ZERO_PAGE(0);
1501                         page_cache_get(page);
1502                 }
1503
1504                 /*
1505                  * Ok, we have the page, and it's up-to-date, so
1506                  * now we can copy it to user space...
1507                  *
1508                  * The actor routine returns how many bytes were actually used..
1509                  * NOTE! This may not be the same as how much of a user buffer
1510                  * we filled up (we may be padding etc), so we can only update
1511                  * "pos" here (the actor routine has to update the user buffer
1512                  * pointers and the remaining count).
1513                  */
1514                 ret = actor(desc, page, offset, nr);
1515                 offset += ret;
1516                 index += offset >> PAGE_CACHE_SHIFT;
1517                 offset &= ~PAGE_CACHE_MASK;
1518
1519                 page_cache_release(page);
1520                 if (ret != nr || !desc->count)
1521                         break;
1522
1523                 cond_resched();
1524         }
1525
1526         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1527         file_accessed(filp);
1528 }
1529
1530 static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1531                 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
1532 {
1533         struct file *filp = iocb->ki_filp;
1534         ssize_t retval;
1535         unsigned long seg;
1536         size_t count;
1537         loff_t *ppos = &iocb->ki_pos;
1538
1539         retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1540         if (retval)
1541                 return retval;
1542
1543         for (seg = 0; seg < nr_segs; seg++) {
1544                 read_descriptor_t desc;
1545
1546                 desc.written = 0;
1547                 desc.arg.buf = iov[seg].iov_base;
1548                 desc.count = iov[seg].iov_len;
1549                 if (desc.count == 0)
1550                         continue;
1551                 desc.error = 0;
1552                 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1553                 retval += desc.written;
1554                 if (desc.error) {
1555                         retval = retval ?: desc.error;
1556                         break;
1557                 }
1558                 if (desc.count > 0)
1559                         break;
1560         }
1561         return retval;
1562 }
1563
1564 static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
1565                                 struct pipe_inode_info *pipe, size_t len,
1566                                 unsigned int flags)
1567 {
1568         struct address_space *mapping = in->f_mapping;
1569         struct inode *inode = mapping->host;
1570         unsigned int loff, nr_pages, req_pages;
1571         struct page *pages[PIPE_DEF_BUFFERS];
1572         struct partial_page partial[PIPE_DEF_BUFFERS];
1573         struct page *page;
1574         pgoff_t index, end_index;
1575         loff_t isize, left;
1576         int error, page_nr;
1577         struct splice_pipe_desc spd = {
1578                 .pages = pages,
1579                 .partial = partial,
1580                 .nr_pages_max = PIPE_DEF_BUFFERS,
1581                 .flags = flags,
1582                 .ops = &page_cache_pipe_buf_ops,
1583                 .spd_release = spd_release_page,
1584         };
1585
1586         isize = i_size_read(inode);
1587         if (unlikely(*ppos >= isize))
1588                 return 0;
1589
1590         left = isize - *ppos;
1591         if (unlikely(left < len))
1592                 len = left;
1593
1594         if (splice_grow_spd(pipe, &spd))
1595                 return -ENOMEM;
1596
1597         index = *ppos >> PAGE_CACHE_SHIFT;
1598         loff = *ppos & ~PAGE_CACHE_MASK;
1599         req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1600         nr_pages = min(req_pages, pipe->buffers);
1601
1602         spd.nr_pages = find_get_pages_contig(mapping, index,
1603                                                 nr_pages, spd.pages);
1604         index += spd.nr_pages;
1605         error = 0;
1606
1607         while (spd.nr_pages < nr_pages) {
1608                 error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
1609                 if (error)
1610                         break;
1611                 unlock_page(page);
1612                 spd.pages[spd.nr_pages++] = page;
1613                 index++;
1614         }
1615
1616         index = *ppos >> PAGE_CACHE_SHIFT;
1617         nr_pages = spd.nr_pages;
1618         spd.nr_pages = 0;
1619
1620         for (page_nr = 0; page_nr < nr_pages; page_nr++) {
1621                 unsigned int this_len;
1622
1623                 if (!len)
1624                         break;
1625
1626                 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
1627                 page = spd.pages[page_nr];
1628
1629                 if (!PageUptodate(page) || page->mapping != mapping) {
1630                         error = shmem_getpage(inode, index, &page,
1631                                                         SGP_CACHE, NULL);
1632                         if (error)
1633                                 break;
1634                         unlock_page(page);
1635                         page_cache_release(spd.pages[page_nr]);
1636                         spd.pages[page_nr] = page;
1637                 }
1638
1639                 isize = i_size_read(inode);
1640                 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1641                 if (unlikely(!isize || index > end_index))
1642                         break;
1643
1644                 if (end_index == index) {
1645                         unsigned int plen;
1646
1647                         plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1648                         if (plen <= loff)
1649                                 break;
1650
1651                         this_len = min(this_len, plen - loff);
1652                         len = this_len;
1653                 }
1654
1655                 spd.partial[page_nr].offset = loff;
1656                 spd.partial[page_nr].len = this_len;
1657                 len -= this_len;
1658                 loff = 0;
1659                 spd.nr_pages++;
1660                 index++;
1661         }
1662
1663         while (page_nr < nr_pages)
1664                 page_cache_release(spd.pages[page_nr++]);
1665
1666         if (spd.nr_pages)
1667                 error = splice_to_pipe(pipe, &spd);
1668
1669         splice_shrink_spd(&spd);
1670
1671         if (error > 0) {
1672                 *ppos += error;
1673                 file_accessed(in);
1674         }
1675         return error;
1676 }
1677
1678 /*
1679  * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
1680  */
1681 static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
1682                                     pgoff_t index, pgoff_t end, int origin)
1683 {
1684         struct page *page;
1685         struct pagevec pvec;
1686         pgoff_t indices[PAGEVEC_SIZE];
1687         bool done = false;
1688         int i;
1689
1690         pagevec_init(&pvec, 0);
1691         pvec.nr = 1;            /* start small: we may be there already */
1692         while (!done) {
1693                 pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
1694                                         pvec.nr, pvec.pages, indices);
1695                 if (!pvec.nr) {
1696                         if (origin == SEEK_DATA)
1697                                 index = end;
1698                         break;
1699                 }
1700                 for (i = 0; i < pvec.nr; i++, index++) {
1701                         if (index < indices[i]) {
1702                                 if (origin == SEEK_HOLE) {
1703                                         done = true;
1704                                         break;
1705                                 }
1706                                 index = indices[i];
1707                         }
1708                         page = pvec.pages[i];
1709                         if (page && !radix_tree_exceptional_entry(page)) {
1710                                 if (!PageUptodate(page))
1711                                         page = NULL;
1712                         }
1713                         if (index >= end ||
1714                             (page && origin == SEEK_DATA) ||
1715                             (!page && origin == SEEK_HOLE)) {
1716                                 done = true;
1717                                 break;
1718                         }
1719                 }
1720                 shmem_deswap_pagevec(&pvec);
1721                 pagevec_release(&pvec);
1722                 pvec.nr = PAGEVEC_SIZE;
1723                 cond_resched();
1724         }
1725         return index;
1726 }
1727
1728 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int origin)
1729 {
1730         struct address_space *mapping;
1731         struct inode *inode;
1732         pgoff_t start, end;
1733         loff_t new_offset;
1734
1735         if (origin != SEEK_DATA && origin != SEEK_HOLE)
1736                 return generic_file_llseek_size(file, offset, origin,
1737                                                         MAX_LFS_FILESIZE);
1738         mapping = file->f_mapping;
1739         inode = mapping->host;
1740         mutex_lock(&inode->i_mutex);
1741         /* We're holding i_mutex so we can access i_size directly */
1742
1743         if (offset < 0)
1744                 offset = -EINVAL;
1745         else if (offset >= inode->i_size)
1746                 offset = -ENXIO;
1747         else {
1748                 start = offset >> PAGE_CACHE_SHIFT;
1749                 end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1750                 new_offset = shmem_seek_hole_data(mapping, start, end, origin);
1751                 new_offset <<= PAGE_CACHE_SHIFT;
1752                 if (new_offset > offset) {
1753                         if (new_offset < inode->i_size)
1754                                 offset = new_offset;
1755                         else if (origin == SEEK_DATA)
1756                                 offset = -ENXIO;
1757                         else
1758                                 offset = inode->i_size;
1759                 }
1760         }
1761
1762         if (offset >= 0 && offset != file->f_pos) {
1763                 file->f_pos = offset;
1764                 file->f_version = 0;
1765         }
1766         mutex_unlock(&inode->i_mutex);
1767         return offset;
1768 }
1769
1770 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
1771                                                          loff_t len)
1772 {
1773         struct inode *inode = file->f_path.dentry->d_inode;
1774         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1775         struct shmem_falloc shmem_falloc;
1776         pgoff_t start, index, end;
1777         int error;
1778
1779         mutex_lock(&inode->i_mutex);
1780
1781         if (mode & FALLOC_FL_PUNCH_HOLE) {
1782                 struct address_space *mapping = file->f_mapping;
1783                 loff_t unmap_start = round_up(offset, PAGE_SIZE);
1784                 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
1785
1786                 if ((u64)unmap_end > (u64)unmap_start)
1787                         unmap_mapping_range(mapping, unmap_start,
1788                                             1 + unmap_end - unmap_start, 0);
1789                 shmem_truncate_range(inode, offset, offset + len - 1);
1790                 /* No need to unmap again: hole-punching leaves COWed pages */
1791                 error = 0;
1792                 goto out;
1793         }
1794
1795         /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
1796         error = inode_newsize_ok(inode, offset + len);
1797         if (error)
1798                 goto out;
1799
1800         start = offset >> PAGE_CACHE_SHIFT;
1801         end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1802         /* Try to avoid a swapstorm if len is impossible to satisfy */
1803         if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
1804                 error = -ENOSPC;
1805                 goto out;
1806         }
1807
1808         shmem_falloc.start = start;
1809         shmem_falloc.next  = start;
1810         shmem_falloc.nr_falloced = 0;
1811         shmem_falloc.nr_unswapped = 0;
1812         spin_lock(&inode->i_lock);
1813         inode->i_private = &shmem_falloc;
1814         spin_unlock(&inode->i_lock);
1815
1816         for (index = start; index < end; index++) {
1817                 struct page *page;
1818
1819                 /*
1820                  * Good, the fallocate(2) manpage permits EINTR: we may have
1821                  * been interrupted because we are using up too much memory.
1822                  */
1823                 if (signal_pending(current))
1824                         error = -EINTR;
1825                 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
1826                         error = -ENOMEM;
1827                 else
1828                         error = shmem_getpage(inode, index, &page, SGP_FALLOC,
1829                                                                         NULL);
1830                 if (error) {
1831                         /* Remove the !PageUptodate pages we added */
1832                         shmem_undo_range(inode,
1833                                 (loff_t)start << PAGE_CACHE_SHIFT,
1834                                 (loff_t)index << PAGE_CACHE_SHIFT, true);
1835                         goto undone;
1836                 }
1837
1838                 /*
1839                  * Inform shmem_writepage() how far we have reached.
1840                  * No need for lock or barrier: we have the page lock.
1841                  */
1842                 shmem_falloc.next++;
1843                 if (!PageUptodate(page))
1844                         shmem_falloc.nr_falloced++;
1845
1846                 /*
1847                  * If !PageUptodate, leave it that way so that freeable pages
1848                  * can be recognized if we need to rollback on error later.
1849                  * But set_page_dirty so that memory pressure will swap rather
1850                  * than free the pages we are allocating (and SGP_CACHE pages
1851                  * might still be clean: we now need to mark those dirty too).
1852                  */
1853                 set_page_dirty(page);
1854                 unlock_page(page);
1855                 page_cache_release(page);
1856                 cond_resched();
1857         }
1858
1859         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
1860                 i_size_write(inode, offset + len);
1861         inode->i_ctime = CURRENT_TIME;
1862 undone:
1863         spin_lock(&inode->i_lock);
1864         inode->i_private = NULL;
1865         spin_unlock(&inode->i_lock);
1866 out:
1867         mutex_unlock(&inode->i_mutex);
1868         return error;
1869 }
1870
1871 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1872 {
1873         struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1874
1875         buf->f_type = TMPFS_MAGIC;
1876         buf->f_bsize = PAGE_CACHE_SIZE;
1877         buf->f_namelen = NAME_MAX;
1878         if (sbinfo->max_blocks) {
1879                 buf->f_blocks = sbinfo->max_blocks;
1880                 buf->f_bavail =
1881                 buf->f_bfree  = sbinfo->max_blocks -
1882                                 percpu_counter_sum(&sbinfo->used_blocks);
1883         }
1884         if (sbinfo->max_inodes) {
1885                 buf->f_files = sbinfo->max_inodes;
1886                 buf->f_ffree = sbinfo->free_inodes;
1887         }
1888         /* else leave those fields 0 like simple_statfs */
1889         return 0;
1890 }
1891
1892 /*
1893  * File creation. Allocate an inode, and we're done..
1894  */
1895 static int
1896 shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
1897 {
1898         struct inode *inode;
1899         int error = -ENOSPC;
1900
1901         inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
1902         if (inode) {
1903                 error = security_inode_init_security(inode, dir,
1904                                                      &dentry->d_name,
1905                                                      shmem_initxattrs, NULL);
1906                 if (error) {
1907                         if (error != -EOPNOTSUPP) {
1908                                 iput(inode);
1909                                 return error;
1910                         }
1911                 }
1912 #ifdef CONFIG_TMPFS_POSIX_ACL
1913                 error = generic_acl_init(inode, dir);
1914                 if (error) {
1915                         iput(inode);
1916                         return error;
1917                 }
1918 #else
1919                 error = 0;
1920 #endif
1921                 dir->i_size += BOGO_DIRENT_SIZE;
1922                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1923                 d_instantiate(dentry, inode);
1924                 dget(dentry); /* Extra count - pin the dentry in core */
1925         }
1926         return error;
1927 }
1928
1929 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1930 {
1931         int error;
1932
1933         if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1934                 return error;
1935         inc_nlink(dir);
1936         return 0;
1937 }
1938
1939 static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
1940                 struct nameidata *nd)
1941 {
1942         return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1943 }
1944
1945 /*
1946  * Link a file..
1947  */
1948 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1949 {
1950         struct inode *inode = old_dentry->d_inode;
1951         int ret;
1952
1953         /*
1954          * No ordinary (disk based) filesystem counts links as inodes;
1955          * but each new link needs a new dentry, pinning lowmem, and
1956          * tmpfs dentries cannot be pruned until they are unlinked.
1957          */
1958         ret = shmem_reserve_inode(inode->i_sb);
1959         if (ret)
1960                 goto out;
1961
1962         dir->i_size += BOGO_DIRENT_SIZE;
1963         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1964         inc_nlink(inode);
1965         ihold(inode);   /* New dentry reference */
1966         dget(dentry);           /* Extra pinning count for the created dentry */
1967         d_instantiate(dentry, inode);
1968 out:
1969         return ret;
1970 }
1971
1972 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1973 {
1974         struct inode *inode = dentry->d_inode;
1975
1976         if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1977                 shmem_free_inode(inode->i_sb);
1978
1979         dir->i_size -= BOGO_DIRENT_SIZE;
1980         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1981         drop_nlink(inode);
1982         dput(dentry);   /* Undo the count from "create" - this does all the work */
1983         return 0;
1984 }
1985
1986 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1987 {
1988         if (!simple_empty(dentry))
1989                 return -ENOTEMPTY;
1990
1991         drop_nlink(dentry->d_inode);
1992         drop_nlink(dir);
1993         return shmem_unlink(dir, dentry);
1994 }
1995
1996 /*
1997  * The VFS layer already does all the dentry stuff for rename,
1998  * we just have to decrement the usage count for the target if
1999  * it exists so that the VFS layer correctly free's it when it
2000  * gets overwritten.
2001  */
2002 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
2003 {
2004         struct inode *inode = old_dentry->d_inode;
2005         int they_are_dirs = S_ISDIR(inode->i_mode);
2006
2007         if (!simple_empty(new_dentry))
2008                 return -ENOTEMPTY;
2009
2010         if (new_dentry->d_inode) {
2011                 (void) shmem_unlink(new_dir, new_dentry);
2012                 if (they_are_dirs)
2013                         drop_nlink(old_dir);
2014         } else if (they_are_dirs) {
2015                 drop_nlink(old_dir);
2016                 inc_nlink(new_dir);
2017         }
2018
2019         old_dir->i_size -= BOGO_DIRENT_SIZE;
2020         new_dir->i_size += BOGO_DIRENT_SIZE;
2021         old_dir->i_ctime = old_dir->i_mtime =
2022         new_dir->i_ctime = new_dir->i_mtime =
2023         inode->i_ctime = CURRENT_TIME;
2024         return 0;
2025 }
2026
2027 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
2028 {
2029         int error;
2030         int len;
2031         struct inode *inode;
2032         struct page *page;
2033         char *kaddr;
2034         struct shmem_inode_info *info;
2035
2036         len = strlen(symname) + 1;
2037         if (len > PAGE_CACHE_SIZE)
2038                 return -ENAMETOOLONG;
2039
2040         inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
2041         if (!inode)
2042                 return -ENOSPC;
2043
2044         error = security_inode_init_security(inode, dir, &dentry->d_name,
2045                                              shmem_initxattrs, NULL);
2046         if (error) {
2047                 if (error != -EOPNOTSUPP) {
2048                         iput(inode);
2049                         return error;
2050                 }
2051                 error = 0;
2052         }
2053
2054         info = SHMEM_I(inode);
2055         inode->i_size = len-1;
2056         if (len <= SHORT_SYMLINK_LEN) {
2057                 info->symlink = kmemdup(symname, len, GFP_KERNEL);
2058                 if (!info->symlink) {
2059                         iput(inode);
2060                         return -ENOMEM;
2061                 }
2062                 inode->i_op = &shmem_short_symlink_operations;
2063         } else {
2064                 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
2065                 if (error) {
2066                         iput(inode);
2067                         return error;
2068                 }
2069                 inode->i_mapping->a_ops = &shmem_aops;
2070                 inode->i_op = &shmem_symlink_inode_operations;
2071                 kaddr = kmap_atomic(page);
2072                 memcpy(kaddr, symname, len);
2073                 kunmap_atomic(kaddr);
2074                 SetPageUptodate(page);
2075                 set_page_dirty(page);
2076                 unlock_page(page);
2077                 page_cache_release(page);
2078         }
2079         dir->i_size += BOGO_DIRENT_SIZE;
2080         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2081         d_instantiate(dentry, inode);
2082         dget(dentry);
2083         return 0;
2084 }
2085
2086 static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd)
2087 {
2088         nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink);
2089         return NULL;
2090 }
2091
2092 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
2093 {
2094         struct page *page = NULL;
2095         int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2096         nd_set_link(nd, error ? ERR_PTR(error) : kmap(page));
2097         if (page)
2098                 unlock_page(page);
2099         return page;
2100 }
2101
2102 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2103 {
2104         if (!IS_ERR(nd_get_link(nd))) {
2105                 struct page *page = cookie;
2106                 kunmap(page);
2107                 mark_page_accessed(page);
2108                 page_cache_release(page);
2109         }
2110 }
2111
2112 #ifdef CONFIG_TMPFS_XATTR
2113 /*
2114  * Superblocks without xattr inode operations may get some security.* xattr
2115  * support from the LSM "for free". As soon as we have any other xattrs
2116  * like ACLs, we also need to implement the security.* handlers at
2117  * filesystem level, though.
2118  */
2119
2120 /*
2121  * Allocate new xattr and copy in the value; but leave the name to callers.
2122  */
2123 static struct shmem_xattr *shmem_xattr_alloc(const void *value, size_t size)
2124 {
2125         struct shmem_xattr *new_xattr;
2126         size_t len;
2127
2128         /* wrap around? */
2129         len = sizeof(*new_xattr) + size;
2130         if (len <= sizeof(*new_xattr))
2131                 return NULL;
2132
2133         new_xattr = kmalloc(len, GFP_KERNEL);
2134         if (!new_xattr)
2135                 return NULL;
2136
2137         new_xattr->size = size;
2138         memcpy(new_xattr->value, value, size);
2139         return new_xattr;
2140 }
2141
2142 /*
2143  * Callback for security_inode_init_security() for acquiring xattrs.
2144  */
2145 static int shmem_initxattrs(struct inode *inode,
2146                             const struct xattr *xattr_array,
2147                             void *fs_info)
2148 {
2149         struct shmem_inode_info *info = SHMEM_I(inode);
2150         const struct xattr *xattr;
2151         struct shmem_xattr *new_xattr;
2152         size_t len;
2153
2154         for (xattr = xattr_array; xattr->name != NULL; xattr++) {
2155                 new_xattr = shmem_xattr_alloc(xattr->value, xattr->value_len);
2156                 if (!new_xattr)
2157                         return -ENOMEM;
2158
2159                 len = strlen(xattr->name) + 1;
2160                 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
2161                                           GFP_KERNEL);
2162                 if (!new_xattr->name) {
2163                         kfree(new_xattr);
2164                         return -ENOMEM;
2165                 }
2166
2167                 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
2168                        XATTR_SECURITY_PREFIX_LEN);
2169                 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
2170                        xattr->name, len);
2171
2172                 spin_lock(&info->lock);
2173                 list_add(&new_xattr->list, &info->xattr_list);
2174                 spin_unlock(&info->lock);
2175         }
2176
2177         return 0;
2178 }
2179
2180 static int shmem_xattr_get(struct dentry *dentry, const char *name,
2181                            void *buffer, size_t size)
2182 {
2183         struct shmem_inode_info *info;
2184         struct shmem_xattr *xattr;
2185         int ret = -ENODATA;
2186
2187         info = SHMEM_I(dentry->d_inode);
2188
2189         spin_lock(&info->lock);
2190         list_for_each_entry(xattr, &info->xattr_list, list) {
2191                 if (strcmp(name, xattr->name))
2192                         continue;
2193
2194                 ret = xattr->size;
2195                 if (buffer) {
2196                         if (size < xattr->size)
2197                                 ret = -ERANGE;
2198                         else
2199                                 memcpy(buffer, xattr->value, xattr->size);
2200                 }
2201                 break;
2202         }
2203         spin_unlock(&info->lock);
2204         return ret;
2205 }
2206
2207 static int shmem_xattr_set(struct inode *inode, const char *name,
2208                            const void *value, size_t size, int flags)
2209 {
2210         struct shmem_inode_info *info = SHMEM_I(inode);
2211         struct shmem_xattr *xattr;
2212         struct shmem_xattr *new_xattr = NULL;
2213         int err = 0;
2214
2215         /* value == NULL means remove */
2216         if (value) {
2217                 new_xattr = shmem_xattr_alloc(value, size);
2218                 if (!new_xattr)
2219                         return -ENOMEM;
2220
2221                 new_xattr->name = kstrdup(name, GFP_KERNEL);
2222                 if (!new_xattr->name) {
2223                         kfree(new_xattr);
2224                         return -ENOMEM;
2225                 }
2226         }
2227
2228         spin_lock(&info->lock);
2229         list_for_each_entry(xattr, &info->xattr_list, list) {
2230                 if (!strcmp(name, xattr->name)) {
2231                         if (flags & XATTR_CREATE) {
2232                                 xattr = new_xattr;
2233                                 err = -EEXIST;
2234                         } else if (new_xattr) {
2235                                 list_replace(&xattr->list, &new_xattr->list);
2236                         } else {
2237                                 list_del(&xattr->list);
2238                         }
2239                         goto out;
2240                 }
2241         }
2242         if (flags & XATTR_REPLACE) {
2243                 xattr = new_xattr;
2244                 err = -ENODATA;
2245         } else {
2246                 list_add(&new_xattr->list, &info->xattr_list);
2247                 xattr = NULL;
2248         }
2249 out:
2250         spin_unlock(&info->lock);
2251         if (xattr)
2252                 kfree(xattr->name);
2253         kfree(xattr);
2254         return err;
2255 }
2256
2257 static const struct xattr_handler *shmem_xattr_handlers[] = {
2258 #ifdef CONFIG_TMPFS_POSIX_ACL
2259         &generic_acl_access_handler,
2260         &generic_acl_default_handler,
2261 #endif
2262         NULL
2263 };
2264
2265 static int shmem_xattr_validate(const char *name)
2266 {
2267         struct { const char *prefix; size_t len; } arr[] = {
2268                 { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
2269                 { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
2270         };
2271         int i;
2272
2273         for (i = 0; i < ARRAY_SIZE(arr); i++) {
2274                 size_t preflen = arr[i].len;
2275                 if (strncmp(name, arr[i].prefix, preflen) == 0) {
2276                         if (!name[preflen])
2277                                 return -EINVAL;
2278                         return 0;
2279                 }
2280         }
2281         return -EOPNOTSUPP;
2282 }
2283
2284 static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
2285                               void *buffer, size_t size)
2286 {
2287         int err;
2288
2289         /*
2290          * If this is a request for a synthetic attribute in the system.*
2291          * namespace use the generic infrastructure to resolve a handler
2292          * for it via sb->s_xattr.
2293          */
2294         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2295                 return generic_getxattr(dentry, name, buffer, size);
2296
2297         err = shmem_xattr_validate(name);
2298         if (err)
2299                 return err;
2300
2301         return shmem_xattr_get(dentry, name, buffer, size);
2302 }
2303
2304 static int shmem_setxattr(struct dentry *dentry, const char *name,
2305                           const void *value, size_t size, int flags)
2306 {
2307         int err;
2308
2309         /*
2310          * If this is a request for a synthetic attribute in the system.*
2311          * namespace use the generic infrastructure to resolve a handler
2312          * for it via sb->s_xattr.
2313          */
2314         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2315                 return generic_setxattr(dentry, name, value, size, flags);
2316
2317         err = shmem_xattr_validate(name);
2318         if (err)
2319                 return err;
2320
2321         if (size == 0)
2322                 value = "";  /* empty EA, do not remove */
2323
2324         return shmem_xattr_set(dentry->d_inode, name, value, size, flags);
2325
2326 }
2327
2328 static int shmem_removexattr(struct dentry *dentry, const char *name)
2329 {
2330         int err;
2331
2332         /*
2333          * If this is a request for a synthetic attribute in the system.*
2334          * namespace use the generic infrastructure to resolve a handler
2335          * for it via sb->s_xattr.
2336          */
2337         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2338                 return generic_removexattr(dentry, name);
2339
2340         err = shmem_xattr_validate(name);
2341         if (err)
2342                 return err;
2343
2344         return shmem_xattr_set(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
2345 }
2346
2347 static bool xattr_is_trusted(const char *name)
2348 {
2349         return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
2350 }
2351
2352 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
2353 {
2354         bool trusted = capable(CAP_SYS_ADMIN);
2355         struct shmem_xattr *xattr;
2356         struct shmem_inode_info *info;
2357         size_t used = 0;
2358
2359         info = SHMEM_I(dentry->d_inode);
2360
2361         spin_lock(&info->lock);
2362         list_for_each_entry(xattr, &info->xattr_list, list) {
2363                 size_t len;
2364
2365                 /* skip "trusted." attributes for unprivileged callers */
2366                 if (!trusted && xattr_is_trusted(xattr->name))
2367                         continue;
2368
2369                 len = strlen(xattr->name) + 1;
2370                 used += len;
2371                 if (buffer) {
2372                         if (size < used) {
2373                                 used = -ERANGE;
2374                                 break;
2375                         }
2376                         memcpy(buffer, xattr->name, len);
2377                         buffer += len;
2378                 }
2379         }
2380         spin_unlock(&info->lock);
2381
2382         return used;
2383 }
2384 #endif /* CONFIG_TMPFS_XATTR */
2385
2386 static const struct inode_operations shmem_short_symlink_operations = {
2387         .readlink       = generic_readlink,
2388         .follow_link    = shmem_follow_short_symlink,
2389 #ifdef CONFIG_TMPFS_XATTR
2390         .setxattr       = shmem_setxattr,
2391         .getxattr       = shmem_getxattr,
2392         .listxattr      = shmem_listxattr,
2393         .removexattr    = shmem_removexattr,
2394 #endif
2395 };
2396
2397 static const struct inode_operations shmem_symlink_inode_operations = {
2398         .readlink       = generic_readlink,
2399         .follow_link    = shmem_follow_link,
2400         .put_link       = shmem_put_link,
2401 #ifdef CONFIG_TMPFS_XATTR
2402         .setxattr       = shmem_setxattr,
2403         .getxattr       = shmem_getxattr,
2404         .listxattr      = shmem_listxattr,
2405         .removexattr    = shmem_removexattr,
2406 #endif
2407 };
2408
2409 static struct dentry *shmem_get_parent(struct dentry *child)
2410 {
2411         return ERR_PTR(-ESTALE);
2412 }
2413
2414 static int shmem_match(struct inode *ino, void *vfh)
2415 {
2416         __u32 *fh = vfh;
2417         __u64 inum = fh[2];
2418         inum = (inum << 32) | fh[1];
2419         return ino->i_ino == inum && fh[0] == ino->i_generation;
2420 }
2421
2422 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2423                 struct fid *fid, int fh_len, int fh_type)
2424 {
2425         struct inode *inode;
2426         struct dentry *dentry = NULL;
2427         u64 inum = fid->raw[2];
2428         inum = (inum << 32) | fid->raw[1];
2429
2430         if (fh_len < 3)
2431                 return NULL;
2432
2433         inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2434                         shmem_match, fid->raw);
2435         if (inode) {
2436                 dentry = d_find_alias(inode);
2437                 iput(inode);
2438         }
2439
2440         return dentry;
2441 }
2442
2443 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
2444                                 struct inode *parent)
2445 {
2446         if (*len < 3) {
2447                 *len = 3;
2448                 return 255;
2449         }
2450
2451         if (inode_unhashed(inode)) {
2452                 /* Unfortunately insert_inode_hash is not idempotent,
2453                  * so as we hash inodes here rather than at creation
2454                  * time, we need a lock to ensure we only try
2455                  * to do it once
2456                  */
2457                 static DEFINE_SPINLOCK(lock);
2458                 spin_lock(&lock);
2459                 if (inode_unhashed(inode))
2460                         __insert_inode_hash(inode,
2461                                             inode->i_ino + inode->i_generation);
2462                 spin_unlock(&lock);
2463         }
2464
2465         fh[0] = inode->i_generation;
2466         fh[1] = inode->i_ino;
2467         fh[2] = ((__u64)inode->i_ino) >> 32;
2468
2469         *len = 3;
2470         return 1;
2471 }
2472
2473 static const struct export_operations shmem_export_ops = {
2474         .get_parent     = shmem_get_parent,
2475         .encode_fh      = shmem_encode_fh,
2476         .fh_to_dentry   = shmem_fh_to_dentry,
2477 };
2478
2479 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2480                                bool remount)
2481 {
2482         char *this_char, *value, *rest;
2483         uid_t uid;
2484         gid_t gid;
2485
2486         while (options != NULL) {
2487                 this_char = options;
2488                 for (;;) {
2489                         /*
2490                          * NUL-terminate this option: unfortunately,
2491                          * mount options form a comma-separated list,
2492                          * but mpol's nodelist may also contain commas.
2493                          */
2494                         options = strchr(options, ',');
2495                         if (options == NULL)
2496                                 break;
2497                         options++;
2498                         if (!isdigit(*options)) {
2499                                 options[-1] = '\0';
2500                                 break;
2501                         }
2502                 }
2503                 if (!*this_char)
2504                         continue;
2505                 if ((value = strchr(this_char,'=')) != NULL) {
2506                         *value++ = 0;
2507                 } else {
2508                         printk(KERN_ERR
2509                             "tmpfs: No value for mount option '%s'\n",
2510                             this_char);
2511                         return 1;
2512                 }
2513
2514                 if (!strcmp(this_char,"size")) {
2515                         unsigned long long size;
2516                         size = memparse(value,&rest);
2517                         if (*rest == '%') {
2518                                 size <<= PAGE_SHIFT;
2519                                 size *= totalram_pages;
2520                                 do_div(size, 100);
2521                                 rest++;
2522                         }
2523                         if (*rest)
2524                                 goto bad_val;
2525                         sbinfo->max_blocks =
2526                                 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2527                 } else if (!strcmp(this_char,"nr_blocks")) {
2528                         sbinfo->max_blocks = memparse(value, &rest);
2529                         if (*rest)
2530                                 goto bad_val;
2531                 } else if (!strcmp(this_char,"nr_inodes")) {
2532                         sbinfo->max_inodes = memparse(value, &rest);
2533                         if (*rest)
2534                                 goto bad_val;
2535                 } else if (!strcmp(this_char,"mode")) {
2536                         if (remount)
2537                                 continue;
2538                         sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2539                         if (*rest)
2540                                 goto bad_val;
2541                 } else if (!strcmp(this_char,"uid")) {
2542                         if (remount)
2543                                 continue;
2544                         uid = simple_strtoul(value, &rest, 0);
2545                         if (*rest)
2546                                 goto bad_val;
2547                         sbinfo->uid = make_kuid(current_user_ns(), uid);
2548                         if (!uid_valid(sbinfo->uid))
2549                                 goto bad_val;
2550                 } else if (!strcmp(this_char,"gid")) {
2551                         if (remount)
2552                                 continue;
2553                         gid = simple_strtoul(value, &rest, 0);
2554                         if (*rest)
2555                                 goto bad_val;
2556                         sbinfo->gid = make_kgid(current_user_ns(), gid);
2557                         if (!gid_valid(sbinfo->gid))
2558                                 goto bad_val;
2559                 } else if (!strcmp(this_char,"mpol")) {
2560                         if (mpol_parse_str(value, &sbinfo->mpol, 1))
2561                                 goto bad_val;
2562                 } else {
2563                         printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2564                                this_char);
2565                         return 1;
2566                 }
2567         }
2568         return 0;
2569
2570 bad_val:
2571         printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2572                value, this_char);
2573         return 1;
2574
2575 }
2576
2577 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2578 {
2579         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2580         struct shmem_sb_info config = *sbinfo;
2581         unsigned long inodes;
2582         int error = -EINVAL;
2583
2584         if (shmem_parse_options(data, &config, true))
2585                 return error;
2586
2587         spin_lock(&sbinfo->stat_lock);
2588         inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2589         if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
2590                 goto out;
2591         if (config.max_inodes < inodes)
2592                 goto out;
2593         /*
2594          * Those tests disallow limited->unlimited while any are in use;
2595          * but we must separately disallow unlimited->limited, because
2596          * in that case we have no record of how much is already in use.
2597          */
2598         if (config.max_blocks && !sbinfo->max_blocks)
2599                 goto out;
2600         if (config.max_inodes && !sbinfo->max_inodes)
2601                 goto out;
2602
2603         error = 0;
2604         sbinfo->max_blocks  = config.max_blocks;
2605         sbinfo->max_inodes  = config.max_inodes;
2606         sbinfo->free_inodes = config.max_inodes - inodes;
2607
2608         mpol_put(sbinfo->mpol);
2609         sbinfo->mpol        = config.mpol;      /* transfers initial ref */
2610 out:
2611         spin_unlock(&sbinfo->stat_lock);
2612         return error;
2613 }
2614
2615 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
2616 {
2617         struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
2618
2619         if (sbinfo->max_blocks != shmem_default_max_blocks())
2620                 seq_printf(seq, ",size=%luk",
2621                         sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2622         if (sbinfo->max_inodes != shmem_default_max_inodes())
2623                 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2624         if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2625                 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
2626         if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
2627                 seq_printf(seq, ",uid=%u",
2628                                 from_kuid_munged(&init_user_ns, sbinfo->uid));
2629         if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
2630                 seq_printf(seq, ",gid=%u",
2631                                 from_kgid_munged(&init_user_ns, sbinfo->gid));
2632         shmem_show_mpol(seq, sbinfo->mpol);
2633         return 0;
2634 }
2635 #endif /* CONFIG_TMPFS */
2636
2637 static void shmem_put_super(struct super_block *sb)
2638 {
2639         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2640
2641         percpu_counter_destroy(&sbinfo->used_blocks);
2642         kfree(sbinfo);
2643         sb->s_fs_info = NULL;
2644 }
2645
2646 int shmem_fill_super(struct super_block *sb, void *data, int silent)
2647 {
2648         struct inode *inode;
2649         struct shmem_sb_info *sbinfo;
2650         int err = -ENOMEM;
2651
2652         /* Round up to L1_CACHE_BYTES to resist false sharing */
2653         sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2654                                 L1_CACHE_BYTES), GFP_KERNEL);
2655         if (!sbinfo)
2656                 return -ENOMEM;
2657
2658         sbinfo->mode = S_IRWXUGO | S_ISVTX;
2659         sbinfo->uid = current_fsuid();
2660         sbinfo->gid = current_fsgid();
2661         sb->s_fs_info = sbinfo;
2662
2663 #ifdef CONFIG_TMPFS
2664         /*
2665          * Per default we only allow half of the physical ram per
2666          * tmpfs instance, limiting inodes to one per page of lowmem;
2667          * but the internal instance is left unlimited.
2668          */
2669         if (!(sb->s_flags & MS_NOUSER)) {
2670                 sbinfo->max_blocks = shmem_default_max_blocks();
2671                 sbinfo->max_inodes = shmem_default_max_inodes();
2672                 if (shmem_parse_options(data, sbinfo, false)) {
2673                         err = -EINVAL;
2674                         goto failed;
2675                 }
2676         }
2677         sb->s_export_op = &shmem_export_ops;
2678         sb->s_flags |= MS_NOSEC;
2679 #else
2680         sb->s_flags |= MS_NOUSER;
2681 #endif
2682
2683         spin_lock_init(&sbinfo->stat_lock);
2684         if (percpu_counter_init(&sbinfo->used_blocks, 0))
2685                 goto failed;
2686         sbinfo->free_inodes = sbinfo->max_inodes;
2687
2688         sb->s_maxbytes = MAX_LFS_FILESIZE;
2689         sb->s_blocksize = PAGE_CACHE_SIZE;
2690         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2691         sb->s_magic = TMPFS_MAGIC;
2692         sb->s_op = &shmem_ops;
2693         sb->s_time_gran = 1;
2694 #ifdef CONFIG_TMPFS_XATTR
2695         sb->s_xattr = shmem_xattr_handlers;
2696 #endif
2697 #ifdef CONFIG_TMPFS_POSIX_ACL
2698         sb->s_flags |= MS_POSIXACL;
2699 #endif
2700
2701         inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
2702         if (!inode)
2703                 goto failed;
2704         inode->i_uid = sbinfo->uid;
2705         inode->i_gid = sbinfo->gid;
2706         sb->s_root = d_make_root(inode);
2707         if (!sb->s_root)
2708                 goto failed;
2709         return 0;
2710
2711 failed:
2712         shmem_put_super(sb);
2713         return err;
2714 }
2715
2716 static struct kmem_cache *shmem_inode_cachep;
2717
2718 static struct inode *shmem_alloc_inode(struct super_block *sb)
2719 {
2720         struct shmem_inode_info *info;
2721         info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2722         if (!info)
2723                 return NULL;
2724         return &info->vfs_inode;
2725 }
2726
2727 static void shmem_destroy_callback(struct rcu_head *head)
2728 {
2729         struct inode *inode = container_of(head, struct inode, i_rcu);
2730         kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2731 }
2732
2733 static void shmem_destroy_inode(struct inode *inode)
2734 {
2735         if (S_ISREG(inode->i_mode))
2736                 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2737         call_rcu(&inode->i_rcu, shmem_destroy_callback);
2738 }
2739
2740 static void shmem_init_inode(void *foo)
2741 {
2742         struct shmem_inode_info *info = foo;
2743         inode_init_once(&info->vfs_inode);
2744 }
2745
2746 static int shmem_init_inodecache(void)
2747 {
2748         shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2749                                 sizeof(struct shmem_inode_info),
2750                                 0, SLAB_PANIC, shmem_init_inode);
2751         return 0;
2752 }
2753
2754 static void shmem_destroy_inodecache(void)
2755 {
2756         kmem_cache_destroy(shmem_inode_cachep);
2757 }
2758
2759 static const struct address_space_operations shmem_aops = {
2760         .writepage      = shmem_writepage,
2761         .set_page_dirty = __set_page_dirty_no_writeback,
2762 #ifdef CONFIG_TMPFS
2763         .write_begin    = shmem_write_begin,
2764         .write_end      = shmem_write_end,
2765 #endif
2766         .migratepage    = migrate_page,
2767         .error_remove_page = generic_error_remove_page,
2768 };
2769
2770 static const struct file_operations shmem_file_operations = {
2771         .mmap           = shmem_mmap,
2772 #ifdef CONFIG_TMPFS
2773         .llseek         = shmem_file_llseek,
2774         .read           = do_sync_read,
2775         .write          = do_sync_write,
2776         .aio_read       = shmem_file_aio_read,
2777         .aio_write      = generic_file_aio_write,
2778         .fsync          = noop_fsync,
2779         .splice_read    = shmem_file_splice_read,
2780         .splice_write   = generic_file_splice_write,
2781         .fallocate      = shmem_fallocate,
2782 #endif
2783 };
2784
2785 static const struct inode_operations shmem_inode_operations = {
2786         .setattr        = shmem_setattr,
2787 #ifdef CONFIG_TMPFS_XATTR
2788         .setxattr       = shmem_setxattr,
2789         .getxattr       = shmem_getxattr,
2790         .listxattr      = shmem_listxattr,
2791         .removexattr    = shmem_removexattr,
2792 #endif
2793 };
2794
2795 static const struct inode_operations shmem_dir_inode_operations = {
2796 #ifdef CONFIG_TMPFS
2797         .create         = shmem_create,
2798         .lookup         = simple_lookup,
2799         .link           = shmem_link,
2800         .unlink         = shmem_unlink,
2801         .symlink        = shmem_symlink,
2802         .mkdir          = shmem_mkdir,
2803         .rmdir          = shmem_rmdir,
2804         .mknod          = shmem_mknod,
2805         .rename         = shmem_rename,
2806 #endif
2807 #ifdef CONFIG_TMPFS_XATTR
2808         .setxattr       = shmem_setxattr,
2809         .getxattr       = shmem_getxattr,
2810         .listxattr      = shmem_listxattr,
2811         .removexattr    = shmem_removexattr,
2812 #endif
2813 #ifdef CONFIG_TMPFS_POSIX_ACL
2814         .setattr        = shmem_setattr,
2815 #endif
2816 };
2817
2818 static const struct inode_operations shmem_special_inode_operations = {
2819 #ifdef CONFIG_TMPFS_XATTR
2820         .setxattr       = shmem_setxattr,
2821         .getxattr       = shmem_getxattr,
2822         .listxattr      = shmem_listxattr,
2823         .removexattr    = shmem_removexattr,
2824 #endif
2825 #ifdef CONFIG_TMPFS_POSIX_ACL
2826         .setattr        = shmem_setattr,
2827 #endif
2828 };
2829
2830 static const struct super_operations shmem_ops = {
2831         .alloc_inode    = shmem_alloc_inode,
2832         .destroy_inode  = shmem_destroy_inode,
2833 #ifdef CONFIG_TMPFS
2834         .statfs         = shmem_statfs,
2835         .remount_fs     = shmem_remount_fs,
2836         .show_options   = shmem_show_options,
2837 #endif
2838         .evict_inode    = shmem_evict_inode,
2839         .drop_inode     = generic_delete_inode,
2840         .put_super      = shmem_put_super,
2841 };
2842
2843 static const struct vm_operations_struct shmem_vm_ops = {
2844         .fault          = shmem_fault,
2845 #ifdef CONFIG_NUMA
2846         .set_policy     = shmem_set_policy,
2847         .get_policy     = shmem_get_policy,
2848 #endif
2849 };
2850
2851 static struct dentry *shmem_mount(struct file_system_type *fs_type,
2852         int flags, const char *dev_name, void *data)
2853 {
2854         return mount_nodev(fs_type, flags, data, shmem_fill_super);
2855 }
2856
2857 static struct file_system_type shmem_fs_type = {
2858         .owner          = THIS_MODULE,
2859         .name           = "tmpfs",
2860         .mount          = shmem_mount,
2861         .kill_sb        = kill_litter_super,
2862 };
2863
2864 int __init shmem_init(void)
2865 {
2866         int error;
2867
2868         error = bdi_init(&shmem_backing_dev_info);
2869         if (error)
2870                 goto out4;
2871
2872         error = shmem_init_inodecache();
2873         if (error)
2874                 goto out3;
2875
2876         error = register_filesystem(&shmem_fs_type);
2877         if (error) {
2878                 printk(KERN_ERR "Could not register tmpfs\n");
2879                 goto out2;
2880         }
2881
2882         shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER,
2883                                  shmem_fs_type.name, NULL);
2884         if (IS_ERR(shm_mnt)) {
2885                 error = PTR_ERR(shm_mnt);
2886                 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2887                 goto out1;
2888         }
2889         return 0;
2890
2891 out1:
2892         unregister_filesystem(&shmem_fs_type);
2893 out2:
2894         shmem_destroy_inodecache();
2895 out3:
2896         bdi_destroy(&shmem_backing_dev_info);
2897 out4:
2898         shm_mnt = ERR_PTR(error);
2899         return error;
2900 }
2901
2902 #else /* !CONFIG_SHMEM */
2903
2904 /*
2905  * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2906  *
2907  * This is intended for small system where the benefits of the full
2908  * shmem code (swap-backed and resource-limited) are outweighed by
2909  * their complexity. On systems without swap this code should be
2910  * effectively equivalent, but much lighter weight.
2911  */
2912
2913 #include <linux/ramfs.h>
2914
2915 static struct file_system_type shmem_fs_type = {
2916         .name           = "tmpfs",
2917         .mount          = ramfs_mount,
2918         .kill_sb        = kill_litter_super,
2919 };
2920
2921 int __init shmem_init(void)
2922 {
2923         BUG_ON(register_filesystem(&shmem_fs_type) != 0);
2924
2925         shm_mnt = kern_mount(&shmem_fs_type);
2926         BUG_ON(IS_ERR(shm_mnt));
2927
2928         return 0;
2929 }
2930
2931 int shmem_unuse(swp_entry_t swap, struct page *page)
2932 {
2933         return 0;
2934 }
2935
2936 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2937 {
2938         return 0;
2939 }
2940
2941 void shmem_unlock_mapping(struct address_space *mapping)
2942 {
2943 }
2944
2945 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
2946 {
2947         truncate_inode_pages_range(inode->i_mapping, lstart, lend);
2948 }
2949 EXPORT_SYMBOL_GPL(shmem_truncate_range);
2950
2951 #define shmem_vm_ops                            generic_file_vm_ops
2952 #define shmem_file_operations                   ramfs_file_operations
2953 #define shmem_get_inode(sb, dir, mode, dev, flags)      ramfs_get_inode(sb, dir, mode, dev)
2954 #define shmem_acct_size(flags, size)            0
2955 #define shmem_unacct_size(flags, size)          do {} while (0)
2956
2957 #endif /* CONFIG_SHMEM */
2958
2959 /* common code */
2960
2961 /**
2962  * shmem_file_setup - get an unlinked file living in tmpfs
2963  * @name: name for dentry (to be seen in /proc/<pid>/maps
2964  * @size: size to be set for the file
2965  * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2966  */
2967 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
2968 {
2969         int error;
2970         struct file *file;
2971         struct inode *inode;
2972         struct path path;
2973         struct dentry *root;
2974         struct qstr this;
2975
2976         if (IS_ERR(shm_mnt))
2977                 return (void *)shm_mnt;
2978
2979         if (size < 0 || size > MAX_LFS_FILESIZE)
2980                 return ERR_PTR(-EINVAL);
2981
2982         if (shmem_acct_size(flags, size))
2983                 return ERR_PTR(-ENOMEM);
2984
2985         error = -ENOMEM;
2986         this.name = name;
2987         this.len = strlen(name);
2988         this.hash = 0; /* will go */
2989         root = shm_mnt->mnt_root;
2990         path.dentry = d_alloc(root, &this);
2991         if (!path.dentry)
2992                 goto put_memory;
2993         path.mnt = mntget(shm_mnt);
2994
2995         error = -ENOSPC;
2996         inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
2997         if (!inode)
2998                 goto put_dentry;
2999
3000         d_instantiate(path.dentry, inode);
3001         inode->i_size = size;
3002         clear_nlink(inode);     /* It is unlinked */
3003 #ifndef CONFIG_MMU
3004         error = ramfs_nommu_expand_for_mapping(inode, size);
3005         if (error)
3006                 goto put_dentry;
3007 #endif
3008
3009         error = -ENFILE;
3010         file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
3011                   &shmem_file_operations);
3012         if (!file)
3013                 goto put_dentry;
3014
3015         return file;
3016
3017 put_dentry:
3018         path_put(&path);
3019 put_memory:
3020         shmem_unacct_size(flags, size);
3021         return ERR_PTR(error);
3022 }
3023 EXPORT_SYMBOL_GPL(shmem_file_setup);
3024
3025 /**
3026  * shmem_zero_setup - setup a shared anonymous mapping
3027  * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
3028  */
3029 int shmem_zero_setup(struct vm_area_struct *vma)
3030 {
3031         struct file *file;
3032         loff_t size = vma->vm_end - vma->vm_start;
3033
3034         file = shmem_file_setup("dev/zero", size, vma->vm_flags);
3035         if (IS_ERR(file))
3036                 return PTR_ERR(file);
3037
3038         if (vma->vm_file)
3039                 fput(vma->vm_file);
3040         vma->vm_file = file;
3041         vma->vm_ops = &shmem_vm_ops;
3042         vma->vm_flags |= VM_CAN_NONLINEAR;
3043         return 0;
3044 }
3045
3046 /**
3047  * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
3048  * @mapping:    the page's address_space
3049  * @index:      the page index
3050  * @gfp:        the page allocator flags to use if allocating
3051  *
3052  * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
3053  * with any new page allocations done using the specified allocation flags.
3054  * But read_cache_page_gfp() uses the ->readpage() method: which does not
3055  * suit tmpfs, since it may have pages in swapcache, and needs to find those
3056  * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
3057  *
3058  * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
3059  * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
3060  */
3061 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
3062                                          pgoff_t index, gfp_t gfp)
3063 {
3064 #ifdef CONFIG_SHMEM
3065         struct inode *inode = mapping->host;
3066         struct page *page;
3067         int error;
3068
3069         BUG_ON(mapping->a_ops != &shmem_aops);
3070         error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
3071         if (error)
3072                 page = ERR_PTR(error);
3073         else
3074                 unlock_page(page);
3075         return page;
3076 #else
3077         /*
3078          * The tiny !SHMEM case uses ramfs without swap
3079          */
3080         return read_cache_page_gfp(mapping, index, gfp);
3081 #endif
3082 }
3083 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);