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