shmem.c revision ff36b801624d02a876bb7deded6ab860ea3503f2
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) 2002-2005 Hugh Dickins. 10 * Copyright (C) 2002-2005 VERITAS Software Corporation. 11 * Copyright (C) 2004 Andi Kleen, SuSE Labs 12 * 13 * Extended attribute support for tmpfs: 14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> 15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> 16 * 17 * tiny-shmem: 18 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> 19 * 20 * This file is released under the GPL. 21 */ 22 23#include <linux/fs.h> 24#include <linux/init.h> 25#include <linux/vfs.h> 26#include <linux/mount.h> 27#include <linux/pagemap.h> 28#include <linux/file.h> 29#include <linux/mm.h> 30#include <linux/module.h> 31#include <linux/percpu_counter.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/security.h> 55#include <linux/swapops.h> 56#include <linux/mempolicy.h> 57#include <linux/namei.h> 58#include <linux/ctype.h> 59#include <linux/migrate.h> 60#include <linux/highmem.h> 61#include <linux/seq_file.h> 62#include <linux/magic.h> 63 64#include <asm/uaccess.h> 65#include <asm/div64.h> 66#include <asm/pgtable.h> 67 68/* 69 * The maximum size of a shmem/tmpfs file is limited by the maximum size of 70 * its triple-indirect swap vector - see illustration at shmem_swp_entry(). 71 * 72 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel, 73 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum 74 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel, 75 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout. 76 * 77 * We use / and * instead of shifts in the definitions below, so that the swap 78 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE. 79 */ 80#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 81#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 82 83#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 84#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT) 85 86#define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE) 87#define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT)) 88 89#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 90#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 91 92/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 93#define SHMEM_PAGEIN VM_READ 94#define SHMEM_TRUNCATE VM_WRITE 95 96/* Definition to limit shmem_truncate's steps between cond_rescheds */ 97#define LATENCY_LIMIT 64 98 99/* Pretend that each entry is of this size in directory's i_size */ 100#define BOGO_DIRENT_SIZE 20 101 102/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 103enum sgp_type { 104 SGP_READ, /* don't exceed i_size, don't allocate page */ 105 SGP_CACHE, /* don't exceed i_size, may allocate page */ 106 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ 107 SGP_WRITE, /* may exceed i_size, may allocate page */ 108}; 109 110#ifdef CONFIG_TMPFS 111static unsigned long shmem_default_max_blocks(void) 112{ 113 return totalram_pages / 2; 114} 115 116static unsigned long shmem_default_max_inodes(void) 117{ 118 return min(totalram_pages - totalhigh_pages, totalram_pages / 2); 119} 120#endif 121 122static int shmem_getpage(struct inode *inode, unsigned long idx, 123 struct page **pagep, enum sgp_type sgp, int *type); 124 125static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 126{ 127 /* 128 * The above definition of ENTRIES_PER_PAGE, and the use of 129 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 130 * might be reconsidered if it ever diverges from PAGE_SIZE. 131 * 132 * Mobility flags are masked out as swap vectors cannot move 133 */ 134 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, 135 PAGE_CACHE_SHIFT-PAGE_SHIFT); 136} 137 138static inline void shmem_dir_free(struct page *page) 139{ 140 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 141} 142 143static struct page **shmem_dir_map(struct page *page) 144{ 145 return (struct page **)kmap_atomic(page, KM_USER0); 146} 147 148static inline void shmem_dir_unmap(struct page **dir) 149{ 150 kunmap_atomic(dir, KM_USER0); 151} 152 153static swp_entry_t *shmem_swp_map(struct page *page) 154{ 155 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 156} 157 158static inline void shmem_swp_balance_unmap(void) 159{ 160 /* 161 * When passing a pointer to an i_direct entry, to code which 162 * also handles indirect entries and so will shmem_swp_unmap, 163 * we must arrange for the preempt count to remain in balance. 164 * What kmap_atomic of a lowmem page does depends on config 165 * and architecture, so pretend to kmap_atomic some lowmem page. 166 */ 167 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 168} 169 170static inline void shmem_swp_unmap(swp_entry_t *entry) 171{ 172 kunmap_atomic(entry, KM_USER1); 173} 174 175static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 176{ 177 return sb->s_fs_info; 178} 179 180/* 181 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 182 * for shared memory and for shared anonymous (/dev/zero) mappings 183 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 184 * consistent with the pre-accounting of private mappings ... 185 */ 186static inline int shmem_acct_size(unsigned long flags, loff_t size) 187{ 188 return (flags & VM_NORESERVE) ? 189 0 : security_vm_enough_memory_kern(VM_ACCT(size)); 190} 191 192static inline void shmem_unacct_size(unsigned long flags, loff_t size) 193{ 194 if (!(flags & VM_NORESERVE)) 195 vm_unacct_memory(VM_ACCT(size)); 196} 197 198/* 199 * ... whereas tmpfs objects are accounted incrementally as 200 * pages are allocated, in order to allow huge sparse files. 201 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 202 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 203 */ 204static inline int shmem_acct_block(unsigned long flags) 205{ 206 return (flags & VM_NORESERVE) ? 207 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0; 208} 209 210static inline void shmem_unacct_blocks(unsigned long flags, long pages) 211{ 212 if (flags & VM_NORESERVE) 213 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 214} 215 216static const struct super_operations shmem_ops; 217static const struct address_space_operations shmem_aops; 218static const struct file_operations shmem_file_operations; 219static const struct inode_operations shmem_inode_operations; 220static const struct inode_operations shmem_dir_inode_operations; 221static const struct inode_operations shmem_special_inode_operations; 222static const struct vm_operations_struct shmem_vm_ops; 223 224static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 225 .ra_pages = 0, /* No readahead */ 226 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, 227 .unplug_io_fn = default_unplug_io_fn, 228}; 229 230static LIST_HEAD(shmem_swaplist); 231static DEFINE_MUTEX(shmem_swaplist_mutex); 232 233static void shmem_free_blocks(struct inode *inode, long pages) 234{ 235 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 236 if (sbinfo->max_blocks) { 237 percpu_counter_add(&sbinfo->used_blocks, -pages); 238 spin_lock(&inode->i_lock); 239 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 240 spin_unlock(&inode->i_lock); 241 } 242} 243 244static int shmem_reserve_inode(struct super_block *sb) 245{ 246 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 247 if (sbinfo->max_inodes) { 248 spin_lock(&sbinfo->stat_lock); 249 if (!sbinfo->free_inodes) { 250 spin_unlock(&sbinfo->stat_lock); 251 return -ENOSPC; 252 } 253 sbinfo->free_inodes--; 254 spin_unlock(&sbinfo->stat_lock); 255 } 256 return 0; 257} 258 259static void shmem_free_inode(struct super_block *sb) 260{ 261 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 262 if (sbinfo->max_inodes) { 263 spin_lock(&sbinfo->stat_lock); 264 sbinfo->free_inodes++; 265 spin_unlock(&sbinfo->stat_lock); 266 } 267} 268 269/** 270 * shmem_recalc_inode - recalculate the size of an inode 271 * @inode: inode to recalc 272 * 273 * We have to calculate the free blocks since the mm can drop 274 * undirtied hole pages behind our back. 275 * 276 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 277 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 278 * 279 * It has to be called with the spinlock held. 280 */ 281static void shmem_recalc_inode(struct inode *inode) 282{ 283 struct shmem_inode_info *info = SHMEM_I(inode); 284 long freed; 285 286 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 287 if (freed > 0) { 288 info->alloced -= freed; 289 shmem_unacct_blocks(info->flags, freed); 290 shmem_free_blocks(inode, freed); 291 } 292} 293 294/** 295 * shmem_swp_entry - find the swap vector position in the info structure 296 * @info: info structure for the inode 297 * @index: index of the page to find 298 * @page: optional page to add to the structure. Has to be preset to 299 * all zeros 300 * 301 * If there is no space allocated yet it will return NULL when 302 * page is NULL, else it will use the page for the needed block, 303 * setting it to NULL on return to indicate that it has been used. 304 * 305 * The swap vector is organized the following way: 306 * 307 * There are SHMEM_NR_DIRECT entries directly stored in the 308 * shmem_inode_info structure. So small files do not need an addional 309 * allocation. 310 * 311 * For pages with index > SHMEM_NR_DIRECT there is the pointer 312 * i_indirect which points to a page which holds in the first half 313 * doubly indirect blocks, in the second half triple indirect blocks: 314 * 315 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 316 * following layout (for SHMEM_NR_DIRECT == 16): 317 * 318 * i_indirect -> dir --> 16-19 319 * | +-> 20-23 320 * | 321 * +-->dir2 --> 24-27 322 * | +-> 28-31 323 * | +-> 32-35 324 * | +-> 36-39 325 * | 326 * +-->dir3 --> 40-43 327 * +-> 44-47 328 * +-> 48-51 329 * +-> 52-55 330 */ 331static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 332{ 333 unsigned long offset; 334 struct page **dir; 335 struct page *subdir; 336 337 if (index < SHMEM_NR_DIRECT) { 338 shmem_swp_balance_unmap(); 339 return info->i_direct+index; 340 } 341 if (!info->i_indirect) { 342 if (page) { 343 info->i_indirect = *page; 344 *page = NULL; 345 } 346 return NULL; /* need another page */ 347 } 348 349 index -= SHMEM_NR_DIRECT; 350 offset = index % ENTRIES_PER_PAGE; 351 index /= ENTRIES_PER_PAGE; 352 dir = shmem_dir_map(info->i_indirect); 353 354 if (index >= ENTRIES_PER_PAGE/2) { 355 index -= ENTRIES_PER_PAGE/2; 356 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 357 index %= ENTRIES_PER_PAGE; 358 subdir = *dir; 359 if (!subdir) { 360 if (page) { 361 *dir = *page; 362 *page = NULL; 363 } 364 shmem_dir_unmap(dir); 365 return NULL; /* need another page */ 366 } 367 shmem_dir_unmap(dir); 368 dir = shmem_dir_map(subdir); 369 } 370 371 dir += index; 372 subdir = *dir; 373 if (!subdir) { 374 if (!page || !(subdir = *page)) { 375 shmem_dir_unmap(dir); 376 return NULL; /* need a page */ 377 } 378 *dir = subdir; 379 *page = NULL; 380 } 381 shmem_dir_unmap(dir); 382 return shmem_swp_map(subdir) + offset; 383} 384 385static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 386{ 387 long incdec = value? 1: -1; 388 389 entry->val = value; 390 info->swapped += incdec; 391 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 392 struct page *page = kmap_atomic_to_page(entry); 393 set_page_private(page, page_private(page) + incdec); 394 } 395} 396 397/** 398 * shmem_swp_alloc - get the position of the swap entry for the page. 399 * @info: info structure for the inode 400 * @index: index of the page to find 401 * @sgp: check and recheck i_size? skip allocation? 402 * 403 * If the entry does not exist, allocate it. 404 */ 405static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 406{ 407 struct inode *inode = &info->vfs_inode; 408 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 409 struct page *page = NULL; 410 swp_entry_t *entry; 411 412 if (sgp != SGP_WRITE && 413 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 414 return ERR_PTR(-EINVAL); 415 416 while (!(entry = shmem_swp_entry(info, index, &page))) { 417 if (sgp == SGP_READ) 418 return shmem_swp_map(ZERO_PAGE(0)); 419 /* 420 * Test used_blocks against 1 less max_blocks, since we have 1 data 421 * page (and perhaps indirect index pages) yet to allocate: 422 * a waste to allocate index if we cannot allocate data. 423 */ 424 if (sbinfo->max_blocks) { 425 if (percpu_counter_compare(&sbinfo->used_blocks, (sbinfo->max_blocks - 1)) > 0) 426 return ERR_PTR(-ENOSPC); 427 percpu_counter_inc(&sbinfo->used_blocks); 428 spin_lock(&inode->i_lock); 429 inode->i_blocks += BLOCKS_PER_PAGE; 430 spin_unlock(&inode->i_lock); 431 } 432 433 spin_unlock(&info->lock); 434 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); 435 spin_lock(&info->lock); 436 437 if (!page) { 438 shmem_free_blocks(inode, 1); 439 return ERR_PTR(-ENOMEM); 440 } 441 if (sgp != SGP_WRITE && 442 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 443 entry = ERR_PTR(-EINVAL); 444 break; 445 } 446 if (info->next_index <= index) 447 info->next_index = index + 1; 448 } 449 if (page) { 450 /* another task gave its page, or truncated the file */ 451 shmem_free_blocks(inode, 1); 452 shmem_dir_free(page); 453 } 454 if (info->next_index <= index && !IS_ERR(entry)) 455 info->next_index = index + 1; 456 return entry; 457} 458 459/** 460 * shmem_free_swp - free some swap entries in a directory 461 * @dir: pointer to the directory 462 * @edir: pointer after last entry of the directory 463 * @punch_lock: pointer to spinlock when needed for the holepunch case 464 */ 465static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, 466 spinlock_t *punch_lock) 467{ 468 spinlock_t *punch_unlock = NULL; 469 swp_entry_t *ptr; 470 int freed = 0; 471 472 for (ptr = dir; ptr < edir; ptr++) { 473 if (ptr->val) { 474 if (unlikely(punch_lock)) { 475 punch_unlock = punch_lock; 476 punch_lock = NULL; 477 spin_lock(punch_unlock); 478 if (!ptr->val) 479 continue; 480 } 481 free_swap_and_cache(*ptr); 482 *ptr = (swp_entry_t){0}; 483 freed++; 484 } 485 } 486 if (punch_unlock) 487 spin_unlock(punch_unlock); 488 return freed; 489} 490 491static int shmem_map_and_free_swp(struct page *subdir, int offset, 492 int limit, struct page ***dir, spinlock_t *punch_lock) 493{ 494 swp_entry_t *ptr; 495 int freed = 0; 496 497 ptr = shmem_swp_map(subdir); 498 for (; offset < limit; offset += LATENCY_LIMIT) { 499 int size = limit - offset; 500 if (size > LATENCY_LIMIT) 501 size = LATENCY_LIMIT; 502 freed += shmem_free_swp(ptr+offset, ptr+offset+size, 503 punch_lock); 504 if (need_resched()) { 505 shmem_swp_unmap(ptr); 506 if (*dir) { 507 shmem_dir_unmap(*dir); 508 *dir = NULL; 509 } 510 cond_resched(); 511 ptr = shmem_swp_map(subdir); 512 } 513 } 514 shmem_swp_unmap(ptr); 515 return freed; 516} 517 518static void shmem_free_pages(struct list_head *next) 519{ 520 struct page *page; 521 int freed = 0; 522 523 do { 524 page = container_of(next, struct page, lru); 525 next = next->next; 526 shmem_dir_free(page); 527 freed++; 528 if (freed >= LATENCY_LIMIT) { 529 cond_resched(); 530 freed = 0; 531 } 532 } while (next); 533} 534 535static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 536{ 537 struct shmem_inode_info *info = SHMEM_I(inode); 538 unsigned long idx; 539 unsigned long size; 540 unsigned long limit; 541 unsigned long stage; 542 unsigned long diroff; 543 struct page **dir; 544 struct page *topdir; 545 struct page *middir; 546 struct page *subdir; 547 swp_entry_t *ptr; 548 LIST_HEAD(pages_to_free); 549 long nr_pages_to_free = 0; 550 long nr_swaps_freed = 0; 551 int offset; 552 int freed; 553 int punch_hole; 554 spinlock_t *needs_lock; 555 spinlock_t *punch_lock; 556 unsigned long upper_limit; 557 558 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 559 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 560 if (idx >= info->next_index) 561 return; 562 563 spin_lock(&info->lock); 564 info->flags |= SHMEM_TRUNCATE; 565 if (likely(end == (loff_t) -1)) { 566 limit = info->next_index; 567 upper_limit = SHMEM_MAX_INDEX; 568 info->next_index = idx; 569 needs_lock = NULL; 570 punch_hole = 0; 571 } else { 572 if (end + 1 >= inode->i_size) { /* we may free a little more */ 573 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> 574 PAGE_CACHE_SHIFT; 575 upper_limit = SHMEM_MAX_INDEX; 576 } else { 577 limit = (end + 1) >> PAGE_CACHE_SHIFT; 578 upper_limit = limit; 579 } 580 needs_lock = &info->lock; 581 punch_hole = 1; 582 } 583 584 topdir = info->i_indirect; 585 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 586 info->i_indirect = NULL; 587 nr_pages_to_free++; 588 list_add(&topdir->lru, &pages_to_free); 589 } 590 spin_unlock(&info->lock); 591 592 if (info->swapped && idx < SHMEM_NR_DIRECT) { 593 ptr = info->i_direct; 594 size = limit; 595 if (size > SHMEM_NR_DIRECT) 596 size = SHMEM_NR_DIRECT; 597 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); 598 } 599 600 /* 601 * If there are no indirect blocks or we are punching a hole 602 * below indirect blocks, nothing to be done. 603 */ 604 if (!topdir || limit <= SHMEM_NR_DIRECT) 605 goto done2; 606 607 /* 608 * The truncation case has already dropped info->lock, and we're safe 609 * because i_size and next_index have already been lowered, preventing 610 * access beyond. But in the punch_hole case, we still need to take 611 * the lock when updating the swap directory, because there might be 612 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or 613 * shmem_writepage. However, whenever we find we can remove a whole 614 * directory page (not at the misaligned start or end of the range), 615 * we first NULLify its pointer in the level above, and then have no 616 * need to take the lock when updating its contents: needs_lock and 617 * punch_lock (either pointing to info->lock or NULL) manage this. 618 */ 619 620 upper_limit -= SHMEM_NR_DIRECT; 621 limit -= SHMEM_NR_DIRECT; 622 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 623 offset = idx % ENTRIES_PER_PAGE; 624 idx -= offset; 625 626 dir = shmem_dir_map(topdir); 627 stage = ENTRIES_PER_PAGEPAGE/2; 628 if (idx < ENTRIES_PER_PAGEPAGE/2) { 629 middir = topdir; 630 diroff = idx/ENTRIES_PER_PAGE; 631 } else { 632 dir += ENTRIES_PER_PAGE/2; 633 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 634 while (stage <= idx) 635 stage += ENTRIES_PER_PAGEPAGE; 636 middir = *dir; 637 if (*dir) { 638 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 639 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 640 if (!diroff && !offset && upper_limit >= stage) { 641 if (needs_lock) { 642 spin_lock(needs_lock); 643 *dir = NULL; 644 spin_unlock(needs_lock); 645 needs_lock = NULL; 646 } else 647 *dir = NULL; 648 nr_pages_to_free++; 649 list_add(&middir->lru, &pages_to_free); 650 } 651 shmem_dir_unmap(dir); 652 dir = shmem_dir_map(middir); 653 } else { 654 diroff = 0; 655 offset = 0; 656 idx = stage; 657 } 658 } 659 660 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 661 if (unlikely(idx == stage)) { 662 shmem_dir_unmap(dir); 663 dir = shmem_dir_map(topdir) + 664 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 665 while (!*dir) { 666 dir++; 667 idx += ENTRIES_PER_PAGEPAGE; 668 if (idx >= limit) 669 goto done1; 670 } 671 stage = idx + ENTRIES_PER_PAGEPAGE; 672 middir = *dir; 673 if (punch_hole) 674 needs_lock = &info->lock; 675 if (upper_limit >= stage) { 676 if (needs_lock) { 677 spin_lock(needs_lock); 678 *dir = NULL; 679 spin_unlock(needs_lock); 680 needs_lock = NULL; 681 } else 682 *dir = NULL; 683 nr_pages_to_free++; 684 list_add(&middir->lru, &pages_to_free); 685 } 686 shmem_dir_unmap(dir); 687 cond_resched(); 688 dir = shmem_dir_map(middir); 689 diroff = 0; 690 } 691 punch_lock = needs_lock; 692 subdir = dir[diroff]; 693 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { 694 if (needs_lock) { 695 spin_lock(needs_lock); 696 dir[diroff] = NULL; 697 spin_unlock(needs_lock); 698 punch_lock = NULL; 699 } else 700 dir[diroff] = NULL; 701 nr_pages_to_free++; 702 list_add(&subdir->lru, &pages_to_free); 703 } 704 if (subdir && page_private(subdir) /* has swap entries */) { 705 size = limit - idx; 706 if (size > ENTRIES_PER_PAGE) 707 size = ENTRIES_PER_PAGE; 708 freed = shmem_map_and_free_swp(subdir, 709 offset, size, &dir, punch_lock); 710 if (!dir) 711 dir = shmem_dir_map(middir); 712 nr_swaps_freed += freed; 713 if (offset || punch_lock) { 714 spin_lock(&info->lock); 715 set_page_private(subdir, 716 page_private(subdir) - freed); 717 spin_unlock(&info->lock); 718 } else 719 BUG_ON(page_private(subdir) != freed); 720 } 721 offset = 0; 722 } 723done1: 724 shmem_dir_unmap(dir); 725done2: 726 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 727 /* 728 * Call truncate_inode_pages again: racing shmem_unuse_inode 729 * may have swizzled a page in from swap since 730 * truncate_pagecache or generic_delete_inode did it, before we 731 * lowered next_index. Also, though shmem_getpage checks 732 * i_size before adding to cache, no recheck after: so fix the 733 * narrow window there too. 734 * 735 * Recalling truncate_inode_pages_range and unmap_mapping_range 736 * every time for punch_hole (which never got a chance to clear 737 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 738 * yet hardly ever necessary: try to optimize them out later. 739 */ 740 truncate_inode_pages_range(inode->i_mapping, start, end); 741 if (punch_hole) 742 unmap_mapping_range(inode->i_mapping, start, 743 end - start, 1); 744 } 745 746 spin_lock(&info->lock); 747 info->flags &= ~SHMEM_TRUNCATE; 748 info->swapped -= nr_swaps_freed; 749 if (nr_pages_to_free) 750 shmem_free_blocks(inode, nr_pages_to_free); 751 shmem_recalc_inode(inode); 752 spin_unlock(&info->lock); 753 754 /* 755 * Empty swap vector directory pages to be freed? 756 */ 757 if (!list_empty(&pages_to_free)) { 758 pages_to_free.prev->next = NULL; 759 shmem_free_pages(pages_to_free.next); 760 } 761} 762 763static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 764{ 765 struct inode *inode = dentry->d_inode; 766 loff_t newsize = attr->ia_size; 767 int error; 768 769 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE) 770 && newsize != inode->i_size) { 771 struct page *page = NULL; 772 773 if (newsize < inode->i_size) { 774 /* 775 * If truncating down to a partial page, then 776 * if that page is already allocated, hold it 777 * in memory until the truncation is over, so 778 * truncate_partial_page cannnot miss it were 779 * it assigned to swap. 780 */ 781 if (newsize & (PAGE_CACHE_SIZE-1)) { 782 (void) shmem_getpage(inode, 783 newsize >> PAGE_CACHE_SHIFT, 784 &page, SGP_READ, NULL); 785 if (page) 786 unlock_page(page); 787 } 788 /* 789 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 790 * detect if any pages might have been added to cache 791 * after truncate_inode_pages. But we needn't bother 792 * if it's being fully truncated to zero-length: the 793 * nrpages check is efficient enough in that case. 794 */ 795 if (newsize) { 796 struct shmem_inode_info *info = SHMEM_I(inode); 797 spin_lock(&info->lock); 798 info->flags &= ~SHMEM_PAGEIN; 799 spin_unlock(&info->lock); 800 } 801 } 802 803 error = simple_setsize(inode, newsize); 804 if (page) 805 page_cache_release(page); 806 if (error) 807 return error; 808 shmem_truncate_range(inode, newsize, (loff_t)-1); 809 } 810 811 error = inode_change_ok(inode, attr); 812 if (!error) 813 generic_setattr(inode, attr); 814#ifdef CONFIG_TMPFS_POSIX_ACL 815 if (!error && (attr->ia_valid & ATTR_MODE)) 816 error = generic_acl_chmod(inode); 817#endif 818 return error; 819} 820 821static void shmem_delete_inode(struct inode *inode) 822{ 823 struct shmem_inode_info *info = SHMEM_I(inode); 824 825 if (inode->i_mapping->a_ops == &shmem_aops) { 826 truncate_inode_pages(inode->i_mapping, 0); 827 shmem_unacct_size(info->flags, inode->i_size); 828 inode->i_size = 0; 829 shmem_truncate_range(inode, 0, (loff_t)-1); 830 if (!list_empty(&info->swaplist)) { 831 mutex_lock(&shmem_swaplist_mutex); 832 list_del_init(&info->swaplist); 833 mutex_unlock(&shmem_swaplist_mutex); 834 } 835 } 836 BUG_ON(inode->i_blocks); 837 shmem_free_inode(inode->i_sb); 838 clear_inode(inode); 839} 840 841static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 842{ 843 swp_entry_t *ptr; 844 845 for (ptr = dir; ptr < edir; ptr++) { 846 if (ptr->val == entry.val) 847 return ptr - dir; 848 } 849 return -1; 850} 851 852static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 853{ 854 struct inode *inode; 855 unsigned long idx; 856 unsigned long size; 857 unsigned long limit; 858 unsigned long stage; 859 struct page **dir; 860 struct page *subdir; 861 swp_entry_t *ptr; 862 int offset; 863 int error; 864 865 idx = 0; 866 ptr = info->i_direct; 867 spin_lock(&info->lock); 868 if (!info->swapped) { 869 list_del_init(&info->swaplist); 870 goto lost2; 871 } 872 limit = info->next_index; 873 size = limit; 874 if (size > SHMEM_NR_DIRECT) 875 size = SHMEM_NR_DIRECT; 876 offset = shmem_find_swp(entry, ptr, ptr+size); 877 if (offset >= 0) 878 goto found; 879 if (!info->i_indirect) 880 goto lost2; 881 882 dir = shmem_dir_map(info->i_indirect); 883 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 884 885 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 886 if (unlikely(idx == stage)) { 887 shmem_dir_unmap(dir-1); 888 if (cond_resched_lock(&info->lock)) { 889 /* check it has not been truncated */ 890 if (limit > info->next_index) { 891 limit = info->next_index; 892 if (idx >= limit) 893 goto lost2; 894 } 895 } 896 dir = shmem_dir_map(info->i_indirect) + 897 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 898 while (!*dir) { 899 dir++; 900 idx += ENTRIES_PER_PAGEPAGE; 901 if (idx >= limit) 902 goto lost1; 903 } 904 stage = idx + ENTRIES_PER_PAGEPAGE; 905 subdir = *dir; 906 shmem_dir_unmap(dir); 907 dir = shmem_dir_map(subdir); 908 } 909 subdir = *dir; 910 if (subdir && page_private(subdir)) { 911 ptr = shmem_swp_map(subdir); 912 size = limit - idx; 913 if (size > ENTRIES_PER_PAGE) 914 size = ENTRIES_PER_PAGE; 915 offset = shmem_find_swp(entry, ptr, ptr+size); 916 shmem_swp_unmap(ptr); 917 if (offset >= 0) { 918 shmem_dir_unmap(dir); 919 goto found; 920 } 921 } 922 } 923lost1: 924 shmem_dir_unmap(dir-1); 925lost2: 926 spin_unlock(&info->lock); 927 return 0; 928found: 929 idx += offset; 930 inode = igrab(&info->vfs_inode); 931 spin_unlock(&info->lock); 932 933 /* 934 * Move _head_ to start search for next from here. 935 * But be careful: shmem_delete_inode checks list_empty without taking 936 * mutex, and there's an instant in list_move_tail when info->swaplist 937 * would appear empty, if it were the only one on shmem_swaplist. We 938 * could avoid doing it if inode NULL; or use this minor optimization. 939 */ 940 if (shmem_swaplist.next != &info->swaplist) 941 list_move_tail(&shmem_swaplist, &info->swaplist); 942 mutex_unlock(&shmem_swaplist_mutex); 943 944 error = 1; 945 if (!inode) 946 goto out; 947 /* 948 * Charge page using GFP_KERNEL while we can wait. 949 * Charged back to the user(not to caller) when swap account is used. 950 * add_to_page_cache() will be called with GFP_NOWAIT. 951 */ 952 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); 953 if (error) 954 goto out; 955 error = radix_tree_preload(GFP_KERNEL); 956 if (error) { 957 mem_cgroup_uncharge_cache_page(page); 958 goto out; 959 } 960 error = 1; 961 962 spin_lock(&info->lock); 963 ptr = shmem_swp_entry(info, idx, NULL); 964 if (ptr && ptr->val == entry.val) { 965 error = add_to_page_cache_locked(page, inode->i_mapping, 966 idx, GFP_NOWAIT); 967 /* does mem_cgroup_uncharge_cache_page on error */ 968 } else /* we must compensate for our precharge above */ 969 mem_cgroup_uncharge_cache_page(page); 970 971 if (error == -EEXIST) { 972 struct page *filepage = find_get_page(inode->i_mapping, idx); 973 error = 1; 974 if (filepage) { 975 /* 976 * There might be a more uptodate page coming down 977 * from a stacked writepage: forget our swappage if so. 978 */ 979 if (PageUptodate(filepage)) 980 error = 0; 981 page_cache_release(filepage); 982 } 983 } 984 if (!error) { 985 delete_from_swap_cache(page); 986 set_page_dirty(page); 987 info->flags |= SHMEM_PAGEIN; 988 shmem_swp_set(info, ptr, 0); 989 swap_free(entry); 990 error = 1; /* not an error, but entry was found */ 991 } 992 if (ptr) 993 shmem_swp_unmap(ptr); 994 spin_unlock(&info->lock); 995 radix_tree_preload_end(); 996out: 997 unlock_page(page); 998 page_cache_release(page); 999 iput(inode); /* allows for NULL */ 1000 return error; 1001} 1002 1003/* 1004 * shmem_unuse() search for an eventually swapped out shmem page. 1005 */ 1006int shmem_unuse(swp_entry_t entry, struct page *page) 1007{ 1008 struct list_head *p, *next; 1009 struct shmem_inode_info *info; 1010 int found = 0; 1011 1012 mutex_lock(&shmem_swaplist_mutex); 1013 list_for_each_safe(p, next, &shmem_swaplist) { 1014 info = list_entry(p, struct shmem_inode_info, swaplist); 1015 found = shmem_unuse_inode(info, entry, page); 1016 cond_resched(); 1017 if (found) 1018 goto out; 1019 } 1020 mutex_unlock(&shmem_swaplist_mutex); 1021 /* 1022 * Can some race bring us here? We've been holding page lock, 1023 * so I think not; but would rather try again later than BUG() 1024 */ 1025 unlock_page(page); 1026 page_cache_release(page); 1027out: 1028 return (found < 0) ? found : 0; 1029} 1030 1031/* 1032 * Move the page from the page cache to the swap cache. 1033 */ 1034static int shmem_writepage(struct page *page, struct writeback_control *wbc) 1035{ 1036 struct shmem_inode_info *info; 1037 swp_entry_t *entry, swap; 1038 struct address_space *mapping; 1039 unsigned long index; 1040 struct inode *inode; 1041 1042 BUG_ON(!PageLocked(page)); 1043 mapping = page->mapping; 1044 index = page->index; 1045 inode = mapping->host; 1046 info = SHMEM_I(inode); 1047 if (info->flags & VM_LOCKED) 1048 goto redirty; 1049 if (!total_swap_pages) 1050 goto redirty; 1051 1052 /* 1053 * shmem_backing_dev_info's capabilities prevent regular writeback or 1054 * sync from ever calling shmem_writepage; but a stacking filesystem 1055 * may use the ->writepage of its underlying filesystem, in which case 1056 * tmpfs should write out to swap only in response to memory pressure, 1057 * and not for the writeback threads or sync. However, in those cases, 1058 * we do still want to check if there's a redundant swappage to be 1059 * discarded. 1060 */ 1061 if (wbc->for_reclaim) 1062 swap = get_swap_page(); 1063 else 1064 swap.val = 0; 1065 1066 spin_lock(&info->lock); 1067 if (index >= info->next_index) { 1068 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1069 goto unlock; 1070 } 1071 entry = shmem_swp_entry(info, index, NULL); 1072 if (entry->val) { 1073 /* 1074 * The more uptodate page coming down from a stacked 1075 * writepage should replace our old swappage. 1076 */ 1077 free_swap_and_cache(*entry); 1078 shmem_swp_set(info, entry, 0); 1079 } 1080 shmem_recalc_inode(inode); 1081 1082 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1083 remove_from_page_cache(page); 1084 shmem_swp_set(info, entry, swap.val); 1085 shmem_swp_unmap(entry); 1086 if (list_empty(&info->swaplist)) 1087 inode = igrab(inode); 1088 else 1089 inode = NULL; 1090 spin_unlock(&info->lock); 1091 swap_shmem_alloc(swap); 1092 BUG_ON(page_mapped(page)); 1093 page_cache_release(page); /* pagecache ref */ 1094 swap_writepage(page, wbc); 1095 if (inode) { 1096 mutex_lock(&shmem_swaplist_mutex); 1097 /* move instead of add in case we're racing */ 1098 list_move_tail(&info->swaplist, &shmem_swaplist); 1099 mutex_unlock(&shmem_swaplist_mutex); 1100 iput(inode); 1101 } 1102 return 0; 1103 } 1104 1105 shmem_swp_unmap(entry); 1106unlock: 1107 spin_unlock(&info->lock); 1108 /* 1109 * add_to_swap_cache() doesn't return -EEXIST, so we can safely 1110 * clear SWAP_HAS_CACHE flag. 1111 */ 1112 swapcache_free(swap, NULL); 1113redirty: 1114 set_page_dirty(page); 1115 if (wbc->for_reclaim) 1116 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1117 unlock_page(page); 1118 return 0; 1119} 1120 1121#ifdef CONFIG_NUMA 1122#ifdef CONFIG_TMPFS 1123static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) 1124{ 1125 char buffer[64]; 1126 1127 if (!mpol || mpol->mode == MPOL_DEFAULT) 1128 return; /* show nothing */ 1129 1130 mpol_to_str(buffer, sizeof(buffer), mpol, 1); 1131 1132 seq_printf(seq, ",mpol=%s", buffer); 1133} 1134 1135static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1136{ 1137 struct mempolicy *mpol = NULL; 1138 if (sbinfo->mpol) { 1139 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ 1140 mpol = sbinfo->mpol; 1141 mpol_get(mpol); 1142 spin_unlock(&sbinfo->stat_lock); 1143 } 1144 return mpol; 1145} 1146#endif /* CONFIG_TMPFS */ 1147 1148static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1149 struct shmem_inode_info *info, unsigned long idx) 1150{ 1151 struct mempolicy mpol, *spol; 1152 struct vm_area_struct pvma; 1153 struct page *page; 1154 1155 spol = mpol_cond_copy(&mpol, 1156 mpol_shared_policy_lookup(&info->policy, idx)); 1157 1158 /* Create a pseudo vma that just contains the policy */ 1159 pvma.vm_start = 0; 1160 pvma.vm_pgoff = idx; 1161 pvma.vm_ops = NULL; 1162 pvma.vm_policy = spol; 1163 page = swapin_readahead(entry, gfp, &pvma, 0); 1164 return page; 1165} 1166 1167static struct page *shmem_alloc_page(gfp_t gfp, 1168 struct shmem_inode_info *info, unsigned long idx) 1169{ 1170 struct vm_area_struct pvma; 1171 1172 /* Create a pseudo vma that just contains the policy */ 1173 pvma.vm_start = 0; 1174 pvma.vm_pgoff = idx; 1175 pvma.vm_ops = NULL; 1176 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1177 1178 /* 1179 * alloc_page_vma() will drop the shared policy reference 1180 */ 1181 return alloc_page_vma(gfp, &pvma, 0); 1182} 1183#else /* !CONFIG_NUMA */ 1184#ifdef CONFIG_TMPFS 1185static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) 1186{ 1187} 1188#endif /* CONFIG_TMPFS */ 1189 1190static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1191 struct shmem_inode_info *info, unsigned long idx) 1192{ 1193 return swapin_readahead(entry, gfp, NULL, 0); 1194} 1195 1196static inline struct page *shmem_alloc_page(gfp_t gfp, 1197 struct shmem_inode_info *info, unsigned long idx) 1198{ 1199 return alloc_page(gfp); 1200} 1201#endif /* CONFIG_NUMA */ 1202 1203#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) 1204static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1205{ 1206 return NULL; 1207} 1208#endif 1209 1210/* 1211 * shmem_getpage - either get the page from swap or allocate a new one 1212 * 1213 * If we allocate a new one we do not mark it dirty. That's up to the 1214 * vm. If we swap it in we mark it dirty since we also free the swap 1215 * entry since a page cannot live in both the swap and page cache 1216 */ 1217static int shmem_getpage(struct inode *inode, unsigned long idx, 1218 struct page **pagep, enum sgp_type sgp, int *type) 1219{ 1220 struct address_space *mapping = inode->i_mapping; 1221 struct shmem_inode_info *info = SHMEM_I(inode); 1222 struct shmem_sb_info *sbinfo; 1223 struct page *filepage = *pagep; 1224 struct page *swappage; 1225 struct page *prealloc_page = NULL; 1226 swp_entry_t *entry; 1227 swp_entry_t swap; 1228 gfp_t gfp; 1229 int error; 1230 1231 if (idx >= SHMEM_MAX_INDEX) 1232 return -EFBIG; 1233 1234 if (type) 1235 *type = 0; 1236 1237 /* 1238 * Normally, filepage is NULL on entry, and either found 1239 * uptodate immediately, or allocated and zeroed, or read 1240 * in under swappage, which is then assigned to filepage. 1241 * But shmem_readpage (required for splice) passes in a locked 1242 * filepage, which may be found not uptodate by other callers 1243 * too, and may need to be copied from the swappage read in. 1244 */ 1245repeat: 1246 if (!filepage) 1247 filepage = find_lock_page(mapping, idx); 1248 if (filepage && PageUptodate(filepage)) 1249 goto done; 1250 gfp = mapping_gfp_mask(mapping); 1251 if (!filepage) { 1252 /* 1253 * Try to preload while we can wait, to not make a habit of 1254 * draining atomic reserves; but don't latch on to this cpu. 1255 */ 1256 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1257 if (error) 1258 goto failed; 1259 radix_tree_preload_end(); 1260 if (sgp != SGP_READ && !prealloc_page) { 1261 /* We don't care if this fails */ 1262 prealloc_page = shmem_alloc_page(gfp, info, idx); 1263 if (prealloc_page) { 1264 if (mem_cgroup_cache_charge(prealloc_page, 1265 current->mm, GFP_KERNEL)) { 1266 page_cache_release(prealloc_page); 1267 prealloc_page = NULL; 1268 } 1269 } 1270 } 1271 } 1272 error = 0; 1273 1274 spin_lock(&info->lock); 1275 shmem_recalc_inode(inode); 1276 entry = shmem_swp_alloc(info, idx, sgp); 1277 if (IS_ERR(entry)) { 1278 spin_unlock(&info->lock); 1279 error = PTR_ERR(entry); 1280 goto failed; 1281 } 1282 swap = *entry; 1283 1284 if (swap.val) { 1285 /* Look it up and read it in.. */ 1286 swappage = lookup_swap_cache(swap); 1287 if (!swappage) { 1288 shmem_swp_unmap(entry); 1289 /* here we actually do the io */ 1290 if (type && !(*type & VM_FAULT_MAJOR)) { 1291 __count_vm_event(PGMAJFAULT); 1292 *type |= VM_FAULT_MAJOR; 1293 } 1294 spin_unlock(&info->lock); 1295 swappage = shmem_swapin(swap, gfp, info, idx); 1296 if (!swappage) { 1297 spin_lock(&info->lock); 1298 entry = shmem_swp_alloc(info, idx, sgp); 1299 if (IS_ERR(entry)) 1300 error = PTR_ERR(entry); 1301 else { 1302 if (entry->val == swap.val) 1303 error = -ENOMEM; 1304 shmem_swp_unmap(entry); 1305 } 1306 spin_unlock(&info->lock); 1307 if (error) 1308 goto failed; 1309 goto repeat; 1310 } 1311 wait_on_page_locked(swappage); 1312 page_cache_release(swappage); 1313 goto repeat; 1314 } 1315 1316 /* We have to do this with page locked to prevent races */ 1317 if (!trylock_page(swappage)) { 1318 shmem_swp_unmap(entry); 1319 spin_unlock(&info->lock); 1320 wait_on_page_locked(swappage); 1321 page_cache_release(swappage); 1322 goto repeat; 1323 } 1324 if (PageWriteback(swappage)) { 1325 shmem_swp_unmap(entry); 1326 spin_unlock(&info->lock); 1327 wait_on_page_writeback(swappage); 1328 unlock_page(swappage); 1329 page_cache_release(swappage); 1330 goto repeat; 1331 } 1332 if (!PageUptodate(swappage)) { 1333 shmem_swp_unmap(entry); 1334 spin_unlock(&info->lock); 1335 unlock_page(swappage); 1336 page_cache_release(swappage); 1337 error = -EIO; 1338 goto failed; 1339 } 1340 1341 if (filepage) { 1342 shmem_swp_set(info, entry, 0); 1343 shmem_swp_unmap(entry); 1344 delete_from_swap_cache(swappage); 1345 spin_unlock(&info->lock); 1346 copy_highpage(filepage, swappage); 1347 unlock_page(swappage); 1348 page_cache_release(swappage); 1349 flush_dcache_page(filepage); 1350 SetPageUptodate(filepage); 1351 set_page_dirty(filepage); 1352 swap_free(swap); 1353 } else if (!(error = add_to_page_cache_locked(swappage, mapping, 1354 idx, GFP_NOWAIT))) { 1355 info->flags |= SHMEM_PAGEIN; 1356 shmem_swp_set(info, entry, 0); 1357 shmem_swp_unmap(entry); 1358 delete_from_swap_cache(swappage); 1359 spin_unlock(&info->lock); 1360 filepage = swappage; 1361 set_page_dirty(filepage); 1362 swap_free(swap); 1363 } else { 1364 shmem_swp_unmap(entry); 1365 spin_unlock(&info->lock); 1366 if (error == -ENOMEM) { 1367 /* 1368 * reclaim from proper memory cgroup and 1369 * call memcg's OOM if needed. 1370 */ 1371 error = mem_cgroup_shmem_charge_fallback( 1372 swappage, 1373 current->mm, 1374 gfp); 1375 if (error) { 1376 unlock_page(swappage); 1377 page_cache_release(swappage); 1378 goto failed; 1379 } 1380 } 1381 unlock_page(swappage); 1382 page_cache_release(swappage); 1383 goto repeat; 1384 } 1385 } else if (sgp == SGP_READ && !filepage) { 1386 shmem_swp_unmap(entry); 1387 filepage = find_get_page(mapping, idx); 1388 if (filepage && 1389 (!PageUptodate(filepage) || !trylock_page(filepage))) { 1390 spin_unlock(&info->lock); 1391 wait_on_page_locked(filepage); 1392 page_cache_release(filepage); 1393 filepage = NULL; 1394 goto repeat; 1395 } 1396 spin_unlock(&info->lock); 1397 } else { 1398 shmem_swp_unmap(entry); 1399 sbinfo = SHMEM_SB(inode->i_sb); 1400 if (sbinfo->max_blocks) { 1401 if ((percpu_counter_compare(&sbinfo->used_blocks, sbinfo->max_blocks) > 0) || 1402 shmem_acct_block(info->flags)) { 1403 spin_unlock(&info->lock); 1404 error = -ENOSPC; 1405 goto failed; 1406 } 1407 percpu_counter_inc(&sbinfo->used_blocks); 1408 spin_lock(&inode->i_lock); 1409 inode->i_blocks += BLOCKS_PER_PAGE; 1410 spin_unlock(&inode->i_lock); 1411 } else if (shmem_acct_block(info->flags)) { 1412 spin_unlock(&info->lock); 1413 error = -ENOSPC; 1414 goto failed; 1415 } 1416 1417 if (!filepage) { 1418 int ret; 1419 1420 if (!prealloc_page) { 1421 spin_unlock(&info->lock); 1422 filepage = shmem_alloc_page(gfp, info, idx); 1423 if (!filepage) { 1424 shmem_unacct_blocks(info->flags, 1); 1425 shmem_free_blocks(inode, 1); 1426 error = -ENOMEM; 1427 goto failed; 1428 } 1429 SetPageSwapBacked(filepage); 1430 1431 /* 1432 * Precharge page while we can wait, compensate 1433 * after 1434 */ 1435 error = mem_cgroup_cache_charge(filepage, 1436 current->mm, GFP_KERNEL); 1437 if (error) { 1438 page_cache_release(filepage); 1439 shmem_unacct_blocks(info->flags, 1); 1440 shmem_free_blocks(inode, 1); 1441 filepage = NULL; 1442 goto failed; 1443 } 1444 1445 spin_lock(&info->lock); 1446 } else { 1447 filepage = prealloc_page; 1448 prealloc_page = NULL; 1449 SetPageSwapBacked(filepage); 1450 } 1451 1452 entry = shmem_swp_alloc(info, idx, sgp); 1453 if (IS_ERR(entry)) 1454 error = PTR_ERR(entry); 1455 else { 1456 swap = *entry; 1457 shmem_swp_unmap(entry); 1458 } 1459 ret = error || swap.val; 1460 if (ret) 1461 mem_cgroup_uncharge_cache_page(filepage); 1462 else 1463 ret = add_to_page_cache_lru(filepage, mapping, 1464 idx, GFP_NOWAIT); 1465 /* 1466 * At add_to_page_cache_lru() failure, uncharge will 1467 * be done automatically. 1468 */ 1469 if (ret) { 1470 spin_unlock(&info->lock); 1471 page_cache_release(filepage); 1472 shmem_unacct_blocks(info->flags, 1); 1473 shmem_free_blocks(inode, 1); 1474 filepage = NULL; 1475 if (error) 1476 goto failed; 1477 goto repeat; 1478 } 1479 info->flags |= SHMEM_PAGEIN; 1480 } 1481 1482 info->alloced++; 1483 spin_unlock(&info->lock); 1484 clear_highpage(filepage); 1485 flush_dcache_page(filepage); 1486 SetPageUptodate(filepage); 1487 if (sgp == SGP_DIRTY) 1488 set_page_dirty(filepage); 1489 } 1490done: 1491 *pagep = filepage; 1492 error = 0; 1493 goto out; 1494 1495failed: 1496 if (*pagep != filepage) { 1497 unlock_page(filepage); 1498 page_cache_release(filepage); 1499 } 1500out: 1501 if (prealloc_page) { 1502 mem_cgroup_uncharge_cache_page(prealloc_page); 1503 page_cache_release(prealloc_page); 1504 } 1505 return error; 1506} 1507 1508static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1509{ 1510 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1511 int error; 1512 int ret; 1513 1514 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1515 return VM_FAULT_SIGBUS; 1516 1517 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1518 if (error) 1519 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1520 1521 return ret | VM_FAULT_LOCKED; 1522} 1523 1524#ifdef CONFIG_NUMA 1525static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1526{ 1527 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1528 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1529} 1530 1531static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1532 unsigned long addr) 1533{ 1534 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1535 unsigned long idx; 1536 1537 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1538 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1539} 1540#endif 1541 1542int shmem_lock(struct file *file, int lock, struct user_struct *user) 1543{ 1544 struct inode *inode = file->f_path.dentry->d_inode; 1545 struct shmem_inode_info *info = SHMEM_I(inode); 1546 int retval = -ENOMEM; 1547 1548 spin_lock(&info->lock); 1549 if (lock && !(info->flags & VM_LOCKED)) { 1550 if (!user_shm_lock(inode->i_size, user)) 1551 goto out_nomem; 1552 info->flags |= VM_LOCKED; 1553 mapping_set_unevictable(file->f_mapping); 1554 } 1555 if (!lock && (info->flags & VM_LOCKED) && user) { 1556 user_shm_unlock(inode->i_size, user); 1557 info->flags &= ~VM_LOCKED; 1558 mapping_clear_unevictable(file->f_mapping); 1559 scan_mapping_unevictable_pages(file->f_mapping); 1560 } 1561 retval = 0; 1562 1563out_nomem: 1564 spin_unlock(&info->lock); 1565 return retval; 1566} 1567 1568static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1569{ 1570 file_accessed(file); 1571 vma->vm_ops = &shmem_vm_ops; 1572 vma->vm_flags |= VM_CAN_NONLINEAR; 1573 return 0; 1574} 1575 1576static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, 1577 int mode, dev_t dev, unsigned long flags) 1578{ 1579 struct inode *inode; 1580 struct shmem_inode_info *info; 1581 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1582 1583 if (shmem_reserve_inode(sb)) 1584 return NULL; 1585 1586 inode = new_inode(sb); 1587 if (inode) { 1588 inode_init_owner(inode, dir, mode); 1589 inode->i_blocks = 0; 1590 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1591 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1592 inode->i_generation = get_seconds(); 1593 info = SHMEM_I(inode); 1594 memset(info, 0, (char *)inode - (char *)info); 1595 spin_lock_init(&info->lock); 1596 info->flags = flags & VM_NORESERVE; 1597 INIT_LIST_HEAD(&info->swaplist); 1598 cache_no_acl(inode); 1599 1600 switch (mode & S_IFMT) { 1601 default: 1602 inode->i_op = &shmem_special_inode_operations; 1603 init_special_inode(inode, mode, dev); 1604 break; 1605 case S_IFREG: 1606 inode->i_mapping->a_ops = &shmem_aops; 1607 inode->i_op = &shmem_inode_operations; 1608 inode->i_fop = &shmem_file_operations; 1609 mpol_shared_policy_init(&info->policy, 1610 shmem_get_sbmpol(sbinfo)); 1611 break; 1612 case S_IFDIR: 1613 inc_nlink(inode); 1614 /* Some things misbehave if size == 0 on a directory */ 1615 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1616 inode->i_op = &shmem_dir_inode_operations; 1617 inode->i_fop = &simple_dir_operations; 1618 break; 1619 case S_IFLNK: 1620 /* 1621 * Must not load anything in the rbtree, 1622 * mpol_free_shared_policy will not be called. 1623 */ 1624 mpol_shared_policy_init(&info->policy, NULL); 1625 break; 1626 } 1627 } else 1628 shmem_free_inode(sb); 1629 return inode; 1630} 1631 1632#ifdef CONFIG_TMPFS 1633static const struct inode_operations shmem_symlink_inode_operations; 1634static const struct inode_operations shmem_symlink_inline_operations; 1635 1636/* 1637 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1638 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1639 * below the loop driver, in the generic fashion that many filesystems support. 1640 */ 1641static int shmem_readpage(struct file *file, struct page *page) 1642{ 1643 struct inode *inode = page->mapping->host; 1644 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1645 unlock_page(page); 1646 return error; 1647} 1648 1649static int 1650shmem_write_begin(struct file *file, struct address_space *mapping, 1651 loff_t pos, unsigned len, unsigned flags, 1652 struct page **pagep, void **fsdata) 1653{ 1654 struct inode *inode = mapping->host; 1655 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1656 *pagep = NULL; 1657 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1658} 1659 1660static int 1661shmem_write_end(struct file *file, struct address_space *mapping, 1662 loff_t pos, unsigned len, unsigned copied, 1663 struct page *page, void *fsdata) 1664{ 1665 struct inode *inode = mapping->host; 1666 1667 if (pos + copied > inode->i_size) 1668 i_size_write(inode, pos + copied); 1669 1670 set_page_dirty(page); 1671 unlock_page(page); 1672 page_cache_release(page); 1673 1674 return copied; 1675} 1676 1677static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1678{ 1679 struct inode *inode = filp->f_path.dentry->d_inode; 1680 struct address_space *mapping = inode->i_mapping; 1681 unsigned long index, offset; 1682 enum sgp_type sgp = SGP_READ; 1683 1684 /* 1685 * Might this read be for a stacking filesystem? Then when reading 1686 * holes of a sparse file, we actually need to allocate those pages, 1687 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1688 */ 1689 if (segment_eq(get_fs(), KERNEL_DS)) 1690 sgp = SGP_DIRTY; 1691 1692 index = *ppos >> PAGE_CACHE_SHIFT; 1693 offset = *ppos & ~PAGE_CACHE_MASK; 1694 1695 for (;;) { 1696 struct page *page = NULL; 1697 unsigned long end_index, nr, ret; 1698 loff_t i_size = i_size_read(inode); 1699 1700 end_index = i_size >> PAGE_CACHE_SHIFT; 1701 if (index > end_index) 1702 break; 1703 if (index == end_index) { 1704 nr = i_size & ~PAGE_CACHE_MASK; 1705 if (nr <= offset) 1706 break; 1707 } 1708 1709 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1710 if (desc->error) { 1711 if (desc->error == -EINVAL) 1712 desc->error = 0; 1713 break; 1714 } 1715 if (page) 1716 unlock_page(page); 1717 1718 /* 1719 * We must evaluate after, since reads (unlike writes) 1720 * are called without i_mutex protection against truncate 1721 */ 1722 nr = PAGE_CACHE_SIZE; 1723 i_size = i_size_read(inode); 1724 end_index = i_size >> PAGE_CACHE_SHIFT; 1725 if (index == end_index) { 1726 nr = i_size & ~PAGE_CACHE_MASK; 1727 if (nr <= offset) { 1728 if (page) 1729 page_cache_release(page); 1730 break; 1731 } 1732 } 1733 nr -= offset; 1734 1735 if (page) { 1736 /* 1737 * If users can be writing to this page using arbitrary 1738 * virtual addresses, take care about potential aliasing 1739 * before reading the page on the kernel side. 1740 */ 1741 if (mapping_writably_mapped(mapping)) 1742 flush_dcache_page(page); 1743 /* 1744 * Mark the page accessed if we read the beginning. 1745 */ 1746 if (!offset) 1747 mark_page_accessed(page); 1748 } else { 1749 page = ZERO_PAGE(0); 1750 page_cache_get(page); 1751 } 1752 1753 /* 1754 * Ok, we have the page, and it's up-to-date, so 1755 * now we can copy it to user space... 1756 * 1757 * The actor routine returns how many bytes were actually used.. 1758 * NOTE! This may not be the same as how much of a user buffer 1759 * we filled up (we may be padding etc), so we can only update 1760 * "pos" here (the actor routine has to update the user buffer 1761 * pointers and the remaining count). 1762 */ 1763 ret = actor(desc, page, offset, nr); 1764 offset += ret; 1765 index += offset >> PAGE_CACHE_SHIFT; 1766 offset &= ~PAGE_CACHE_MASK; 1767 1768 page_cache_release(page); 1769 if (ret != nr || !desc->count) 1770 break; 1771 1772 cond_resched(); 1773 } 1774 1775 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1776 file_accessed(filp); 1777} 1778 1779static ssize_t shmem_file_aio_read(struct kiocb *iocb, 1780 const struct iovec *iov, unsigned long nr_segs, loff_t pos) 1781{ 1782 struct file *filp = iocb->ki_filp; 1783 ssize_t retval; 1784 unsigned long seg; 1785 size_t count; 1786 loff_t *ppos = &iocb->ki_pos; 1787 1788 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); 1789 if (retval) 1790 return retval; 1791 1792 for (seg = 0; seg < nr_segs; seg++) { 1793 read_descriptor_t desc; 1794 1795 desc.written = 0; 1796 desc.arg.buf = iov[seg].iov_base; 1797 desc.count = iov[seg].iov_len; 1798 if (desc.count == 0) 1799 continue; 1800 desc.error = 0; 1801 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1802 retval += desc.written; 1803 if (desc.error) { 1804 retval = retval ?: desc.error; 1805 break; 1806 } 1807 if (desc.count > 0) 1808 break; 1809 } 1810 return retval; 1811} 1812 1813static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1814{ 1815 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1816 1817 buf->f_type = TMPFS_MAGIC; 1818 buf->f_bsize = PAGE_CACHE_SIZE; 1819 buf->f_namelen = NAME_MAX; 1820 if (sbinfo->max_blocks) { 1821 buf->f_blocks = sbinfo->max_blocks; 1822 buf->f_bavail = buf->f_bfree = 1823 sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_blocks); 1824 } 1825 if (sbinfo->max_inodes) { 1826 buf->f_files = sbinfo->max_inodes; 1827 buf->f_ffree = sbinfo->free_inodes; 1828 } 1829 /* else leave those fields 0 like simple_statfs */ 1830 return 0; 1831} 1832 1833/* 1834 * File creation. Allocate an inode, and we're done.. 1835 */ 1836static int 1837shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1838{ 1839 struct inode *inode; 1840 int error = -ENOSPC; 1841 1842 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); 1843 if (inode) { 1844 error = security_inode_init_security(inode, dir, NULL, NULL, 1845 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, int 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, int 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 atomic_inc(&inode->i_count); /* 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 = NULL; 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, NULL, NULL, 1985 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 <= (char *)inode - (char *)info) { 1997 /* do it inline */ 1998 memcpy(info, symname, len); 1999 inode->i_op = &shmem_symlink_inline_operations; 2000 } else { 2001 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 2002 if (error) { 2003 iput(inode); 2004 return error; 2005 } 2006 inode->i_mapping->a_ops = &shmem_aops; 2007 inode->i_op = &shmem_symlink_inode_operations; 2008 kaddr = kmap_atomic(page, KM_USER0); 2009 memcpy(kaddr, symname, len); 2010 kunmap_atomic(kaddr, KM_USER0); 2011 set_page_dirty(page); 2012 unlock_page(page); 2013 page_cache_release(page); 2014 } 2015 dir->i_size += BOGO_DIRENT_SIZE; 2016 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 2017 d_instantiate(dentry, inode); 2018 dget(dentry); 2019 return 0; 2020} 2021 2022static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 2023{ 2024 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 2025 return NULL; 2026} 2027 2028static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 2029{ 2030 struct page *page = NULL; 2031 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 2032 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 2033 if (page) 2034 unlock_page(page); 2035 return page; 2036} 2037 2038static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 2039{ 2040 if (!IS_ERR(nd_get_link(nd))) { 2041 struct page *page = cookie; 2042 kunmap(page); 2043 mark_page_accessed(page); 2044 page_cache_release(page); 2045 } 2046} 2047 2048static const struct inode_operations shmem_symlink_inline_operations = { 2049 .readlink = generic_readlink, 2050 .follow_link = shmem_follow_link_inline, 2051}; 2052 2053static const struct inode_operations shmem_symlink_inode_operations = { 2054 .readlink = generic_readlink, 2055 .follow_link = shmem_follow_link, 2056 .put_link = shmem_put_link, 2057}; 2058 2059#ifdef CONFIG_TMPFS_POSIX_ACL 2060/* 2061 * Superblocks without xattr inode operations will get security.* xattr 2062 * support from the VFS "for free". As soon as we have any other xattrs 2063 * like ACLs, we also need to implement the security.* handlers at 2064 * filesystem level, though. 2065 */ 2066 2067static size_t shmem_xattr_security_list(struct dentry *dentry, char *list, 2068 size_t list_len, const char *name, 2069 size_t name_len, int handler_flags) 2070{ 2071 return security_inode_listsecurity(dentry->d_inode, list, list_len); 2072} 2073 2074static int shmem_xattr_security_get(struct dentry *dentry, const char *name, 2075 void *buffer, size_t size, int handler_flags) 2076{ 2077 if (strcmp(name, "") == 0) 2078 return -EINVAL; 2079 return xattr_getsecurity(dentry->d_inode, name, buffer, size); 2080} 2081 2082static int shmem_xattr_security_set(struct dentry *dentry, const char *name, 2083 const void *value, size_t size, int flags, int handler_flags) 2084{ 2085 if (strcmp(name, "") == 0) 2086 return -EINVAL; 2087 return security_inode_setsecurity(dentry->d_inode, name, value, 2088 size, flags); 2089} 2090 2091static const struct xattr_handler shmem_xattr_security_handler = { 2092 .prefix = XATTR_SECURITY_PREFIX, 2093 .list = shmem_xattr_security_list, 2094 .get = shmem_xattr_security_get, 2095 .set = shmem_xattr_security_set, 2096}; 2097 2098static const struct xattr_handler *shmem_xattr_handlers[] = { 2099 &generic_acl_access_handler, 2100 &generic_acl_default_handler, 2101 &shmem_xattr_security_handler, 2102 NULL 2103}; 2104#endif 2105 2106static struct dentry *shmem_get_parent(struct dentry *child) 2107{ 2108 return ERR_PTR(-ESTALE); 2109} 2110 2111static int shmem_match(struct inode *ino, void *vfh) 2112{ 2113 __u32 *fh = vfh; 2114 __u64 inum = fh[2]; 2115 inum = (inum << 32) | fh[1]; 2116 return ino->i_ino == inum && fh[0] == ino->i_generation; 2117} 2118 2119static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2120 struct fid *fid, int fh_len, int fh_type) 2121{ 2122 struct inode *inode; 2123 struct dentry *dentry = NULL; 2124 u64 inum = fid->raw[2]; 2125 inum = (inum << 32) | fid->raw[1]; 2126 2127 if (fh_len < 3) 2128 return NULL; 2129 2130 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2131 shmem_match, fid->raw); 2132 if (inode) { 2133 dentry = d_find_alias(inode); 2134 iput(inode); 2135 } 2136 2137 return dentry; 2138} 2139 2140static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2141 int connectable) 2142{ 2143 struct inode *inode = dentry->d_inode; 2144 2145 if (*len < 3) 2146 return 255; 2147 2148 if (hlist_unhashed(&inode->i_hash)) { 2149 /* Unfortunately insert_inode_hash is not idempotent, 2150 * so as we hash inodes here rather than at creation 2151 * time, we need a lock to ensure we only try 2152 * to do it once 2153 */ 2154 static DEFINE_SPINLOCK(lock); 2155 spin_lock(&lock); 2156 if (hlist_unhashed(&inode->i_hash)) 2157 __insert_inode_hash(inode, 2158 inode->i_ino + inode->i_generation); 2159 spin_unlock(&lock); 2160 } 2161 2162 fh[0] = inode->i_generation; 2163 fh[1] = inode->i_ino; 2164 fh[2] = ((__u64)inode->i_ino) >> 32; 2165 2166 *len = 3; 2167 return 1; 2168} 2169 2170static const struct export_operations shmem_export_ops = { 2171 .get_parent = shmem_get_parent, 2172 .encode_fh = shmem_encode_fh, 2173 .fh_to_dentry = shmem_fh_to_dentry, 2174}; 2175 2176static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 2177 bool remount) 2178{ 2179 char *this_char, *value, *rest; 2180 2181 while (options != NULL) { 2182 this_char = options; 2183 for (;;) { 2184 /* 2185 * NUL-terminate this option: unfortunately, 2186 * mount options form a comma-separated list, 2187 * but mpol's nodelist may also contain commas. 2188 */ 2189 options = strchr(options, ','); 2190 if (options == NULL) 2191 break; 2192 options++; 2193 if (!isdigit(*options)) { 2194 options[-1] = '\0'; 2195 break; 2196 } 2197 } 2198 if (!*this_char) 2199 continue; 2200 if ((value = strchr(this_char,'=')) != NULL) { 2201 *value++ = 0; 2202 } else { 2203 printk(KERN_ERR 2204 "tmpfs: No value for mount option '%s'\n", 2205 this_char); 2206 return 1; 2207 } 2208 2209 if (!strcmp(this_char,"size")) { 2210 unsigned long long size; 2211 size = memparse(value,&rest); 2212 if (*rest == '%') { 2213 size <<= PAGE_SHIFT; 2214 size *= totalram_pages; 2215 do_div(size, 100); 2216 rest++; 2217 } 2218 if (*rest) 2219 goto bad_val; 2220 sbinfo->max_blocks = 2221 DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2222 } else if (!strcmp(this_char,"nr_blocks")) { 2223 sbinfo->max_blocks = memparse(value, &rest); 2224 if (*rest) 2225 goto bad_val; 2226 } else if (!strcmp(this_char,"nr_inodes")) { 2227 sbinfo->max_inodes = memparse(value, &rest); 2228 if (*rest) 2229 goto bad_val; 2230 } else if (!strcmp(this_char,"mode")) { 2231 if (remount) 2232 continue; 2233 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; 2234 if (*rest) 2235 goto bad_val; 2236 } else if (!strcmp(this_char,"uid")) { 2237 if (remount) 2238 continue; 2239 sbinfo->uid = simple_strtoul(value, &rest, 0); 2240 if (*rest) 2241 goto bad_val; 2242 } else if (!strcmp(this_char,"gid")) { 2243 if (remount) 2244 continue; 2245 sbinfo->gid = simple_strtoul(value, &rest, 0); 2246 if (*rest) 2247 goto bad_val; 2248 } else if (!strcmp(this_char,"mpol")) { 2249 if (mpol_parse_str(value, &sbinfo->mpol, 1)) 2250 goto bad_val; 2251 } else { 2252 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2253 this_char); 2254 return 1; 2255 } 2256 } 2257 return 0; 2258 2259bad_val: 2260 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2261 value, this_char); 2262 return 1; 2263 2264} 2265 2266static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2267{ 2268 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2269 struct shmem_sb_info config = *sbinfo; 2270 unsigned long inodes; 2271 int error = -EINVAL; 2272 2273 if (shmem_parse_options(data, &config, true)) 2274 return error; 2275 2276 spin_lock(&sbinfo->stat_lock); 2277 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2278 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) 2279 goto out; 2280 if (config.max_inodes < inodes) 2281 goto out; 2282 /* 2283 * Those tests also disallow limited->unlimited while any are in 2284 * use, so i_blocks will always be zero when max_blocks is zero; 2285 * but we must separately disallow unlimited->limited, because 2286 * in that case we have no record of how much is already in use. 2287 */ 2288 if (config.max_blocks && !sbinfo->max_blocks) 2289 goto out; 2290 if (config.max_inodes && !sbinfo->max_inodes) 2291 goto out; 2292 2293 error = 0; 2294 sbinfo->max_blocks = config.max_blocks; 2295 sbinfo->max_inodes = config.max_inodes; 2296 sbinfo->free_inodes = config.max_inodes - inodes; 2297 2298 mpol_put(sbinfo->mpol); 2299 sbinfo->mpol = config.mpol; /* transfers initial ref */ 2300out: 2301 spin_unlock(&sbinfo->stat_lock); 2302 return error; 2303} 2304 2305static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) 2306{ 2307 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); 2308 2309 if (sbinfo->max_blocks != shmem_default_max_blocks()) 2310 seq_printf(seq, ",size=%luk", 2311 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); 2312 if (sbinfo->max_inodes != shmem_default_max_inodes()) 2313 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); 2314 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) 2315 seq_printf(seq, ",mode=%03o", sbinfo->mode); 2316 if (sbinfo->uid != 0) 2317 seq_printf(seq, ",uid=%u", sbinfo->uid); 2318 if (sbinfo->gid != 0) 2319 seq_printf(seq, ",gid=%u", sbinfo->gid); 2320 shmem_show_mpol(seq, sbinfo->mpol); 2321 return 0; 2322} 2323#endif /* CONFIG_TMPFS */ 2324 2325static void shmem_put_super(struct super_block *sb) 2326{ 2327 kfree(sb->s_fs_info); 2328 sb->s_fs_info = NULL; 2329} 2330 2331int shmem_fill_super(struct super_block *sb, void *data, int silent) 2332{ 2333 struct inode *inode; 2334 struct dentry *root; 2335 struct shmem_sb_info *sbinfo; 2336 int err = -ENOMEM; 2337 2338 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2339 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), 2340 L1_CACHE_BYTES), GFP_KERNEL); 2341 if (!sbinfo) 2342 return -ENOMEM; 2343 2344 sbinfo->mode = S_IRWXUGO | S_ISVTX; 2345 sbinfo->uid = current_fsuid(); 2346 sbinfo->gid = current_fsgid(); 2347 sb->s_fs_info = sbinfo; 2348 2349#ifdef CONFIG_TMPFS 2350 /* 2351 * Per default we only allow half of the physical ram per 2352 * tmpfs instance, limiting inodes to one per page of lowmem; 2353 * but the internal instance is left unlimited. 2354 */ 2355 if (!(sb->s_flags & MS_NOUSER)) { 2356 sbinfo->max_blocks = shmem_default_max_blocks(); 2357 sbinfo->max_inodes = shmem_default_max_inodes(); 2358 if (shmem_parse_options(data, sbinfo, false)) { 2359 err = -EINVAL; 2360 goto failed; 2361 } 2362 } 2363 sb->s_export_op = &shmem_export_ops; 2364#else 2365 sb->s_flags |= MS_NOUSER; 2366#endif 2367 2368 spin_lock_init(&sbinfo->stat_lock); 2369 percpu_counter_init(&sbinfo->used_blocks, 0); 2370 sbinfo->free_inodes = sbinfo->max_inodes; 2371 2372 sb->s_maxbytes = SHMEM_MAX_BYTES; 2373 sb->s_blocksize = PAGE_CACHE_SIZE; 2374 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2375 sb->s_magic = TMPFS_MAGIC; 2376 sb->s_op = &shmem_ops; 2377 sb->s_time_gran = 1; 2378#ifdef CONFIG_TMPFS_POSIX_ACL 2379 sb->s_xattr = shmem_xattr_handlers; 2380 sb->s_flags |= MS_POSIXACL; 2381#endif 2382 2383 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); 2384 if (!inode) 2385 goto failed; 2386 inode->i_uid = sbinfo->uid; 2387 inode->i_gid = sbinfo->gid; 2388 root = d_alloc_root(inode); 2389 if (!root) 2390 goto failed_iput; 2391 sb->s_root = root; 2392 return 0; 2393 2394failed_iput: 2395 iput(inode); 2396failed: 2397 shmem_put_super(sb); 2398 return err; 2399} 2400 2401static struct kmem_cache *shmem_inode_cachep; 2402 2403static struct inode *shmem_alloc_inode(struct super_block *sb) 2404{ 2405 struct shmem_inode_info *p; 2406 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2407 if (!p) 2408 return NULL; 2409 return &p->vfs_inode; 2410} 2411 2412static void shmem_destroy_inode(struct inode *inode) 2413{ 2414 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2415 /* only struct inode is valid if it's an inline symlink */ 2416 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2417 } 2418 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2419} 2420 2421static void init_once(void *foo) 2422{ 2423 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2424 2425 inode_init_once(&p->vfs_inode); 2426} 2427 2428static int init_inodecache(void) 2429{ 2430 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2431 sizeof(struct shmem_inode_info), 2432 0, SLAB_PANIC, init_once); 2433 return 0; 2434} 2435 2436static void destroy_inodecache(void) 2437{ 2438 kmem_cache_destroy(shmem_inode_cachep); 2439} 2440 2441static const struct address_space_operations shmem_aops = { 2442 .writepage = shmem_writepage, 2443 .set_page_dirty = __set_page_dirty_no_writeback, 2444#ifdef CONFIG_TMPFS 2445 .readpage = shmem_readpage, 2446 .write_begin = shmem_write_begin, 2447 .write_end = shmem_write_end, 2448#endif 2449 .migratepage = migrate_page, 2450 .error_remove_page = generic_error_remove_page, 2451}; 2452 2453static const struct file_operations shmem_file_operations = { 2454 .mmap = shmem_mmap, 2455#ifdef CONFIG_TMPFS 2456 .llseek = generic_file_llseek, 2457 .read = do_sync_read, 2458 .write = do_sync_write, 2459 .aio_read = shmem_file_aio_read, 2460 .aio_write = generic_file_aio_write, 2461 .fsync = noop_fsync, 2462 .splice_read = generic_file_splice_read, 2463 .splice_write = generic_file_splice_write, 2464#endif 2465}; 2466 2467static const struct inode_operations shmem_inode_operations = { 2468 .setattr = shmem_notify_change, 2469 .truncate_range = shmem_truncate_range, 2470#ifdef CONFIG_TMPFS_POSIX_ACL 2471 .setxattr = generic_setxattr, 2472 .getxattr = generic_getxattr, 2473 .listxattr = generic_listxattr, 2474 .removexattr = generic_removexattr, 2475 .check_acl = generic_check_acl, 2476#endif 2477 2478}; 2479 2480static const struct inode_operations shmem_dir_inode_operations = { 2481#ifdef CONFIG_TMPFS 2482 .create = shmem_create, 2483 .lookup = simple_lookup, 2484 .link = shmem_link, 2485 .unlink = shmem_unlink, 2486 .symlink = shmem_symlink, 2487 .mkdir = shmem_mkdir, 2488 .rmdir = shmem_rmdir, 2489 .mknod = shmem_mknod, 2490 .rename = shmem_rename, 2491#endif 2492#ifdef CONFIG_TMPFS_POSIX_ACL 2493 .setattr = shmem_notify_change, 2494 .setxattr = generic_setxattr, 2495 .getxattr = generic_getxattr, 2496 .listxattr = generic_listxattr, 2497 .removexattr = generic_removexattr, 2498 .check_acl = generic_check_acl, 2499#endif 2500}; 2501 2502static const struct inode_operations shmem_special_inode_operations = { 2503#ifdef CONFIG_TMPFS_POSIX_ACL 2504 .setattr = shmem_notify_change, 2505 .setxattr = generic_setxattr, 2506 .getxattr = generic_getxattr, 2507 .listxattr = generic_listxattr, 2508 .removexattr = generic_removexattr, 2509 .check_acl = generic_check_acl, 2510#endif 2511}; 2512 2513static const struct super_operations shmem_ops = { 2514 .alloc_inode = shmem_alloc_inode, 2515 .destroy_inode = shmem_destroy_inode, 2516#ifdef CONFIG_TMPFS 2517 .statfs = shmem_statfs, 2518 .remount_fs = shmem_remount_fs, 2519 .show_options = shmem_show_options, 2520#endif 2521 .delete_inode = shmem_delete_inode, 2522 .drop_inode = generic_delete_inode, 2523 .put_super = shmem_put_super, 2524}; 2525 2526static const struct vm_operations_struct shmem_vm_ops = { 2527 .fault = shmem_fault, 2528#ifdef CONFIG_NUMA 2529 .set_policy = shmem_set_policy, 2530 .get_policy = shmem_get_policy, 2531#endif 2532}; 2533 2534 2535static int shmem_get_sb(struct file_system_type *fs_type, 2536 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2537{ 2538 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2539} 2540 2541static struct file_system_type tmpfs_fs_type = { 2542 .owner = THIS_MODULE, 2543 .name = "tmpfs", 2544 .get_sb = shmem_get_sb, 2545 .kill_sb = kill_litter_super, 2546}; 2547 2548int __init init_tmpfs(void) 2549{ 2550 int error; 2551 2552 error = bdi_init(&shmem_backing_dev_info); 2553 if (error) 2554 goto out4; 2555 2556 error = init_inodecache(); 2557 if (error) 2558 goto out3; 2559 2560 error = register_filesystem(&tmpfs_fs_type); 2561 if (error) { 2562 printk(KERN_ERR "Could not register tmpfs\n"); 2563 goto out2; 2564 } 2565 2566 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2567 tmpfs_fs_type.name, NULL); 2568 if (IS_ERR(shm_mnt)) { 2569 error = PTR_ERR(shm_mnt); 2570 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2571 goto out1; 2572 } 2573 return 0; 2574 2575out1: 2576 unregister_filesystem(&tmpfs_fs_type); 2577out2: 2578 destroy_inodecache(); 2579out3: 2580 bdi_destroy(&shmem_backing_dev_info); 2581out4: 2582 shm_mnt = ERR_PTR(error); 2583 return error; 2584} 2585 2586#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2587/** 2588 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2589 * @inode: the inode to be searched 2590 * @pgoff: the offset to be searched 2591 * @pagep: the pointer for the found page to be stored 2592 * @ent: the pointer for the found swap entry to be stored 2593 * 2594 * If a page is found, refcount of it is incremented. Callers should handle 2595 * these refcount. 2596 */ 2597void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2598 struct page **pagep, swp_entry_t *ent) 2599{ 2600 swp_entry_t entry = { .val = 0 }, *ptr; 2601 struct page *page = NULL; 2602 struct shmem_inode_info *info = SHMEM_I(inode); 2603 2604 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2605 goto out; 2606 2607 spin_lock(&info->lock); 2608 ptr = shmem_swp_entry(info, pgoff, NULL); 2609#ifdef CONFIG_SWAP 2610 if (ptr && ptr->val) { 2611 entry.val = ptr->val; 2612 page = find_get_page(&swapper_space, entry.val); 2613 } else 2614#endif 2615 page = find_get_page(inode->i_mapping, pgoff); 2616 if (ptr) 2617 shmem_swp_unmap(ptr); 2618 spin_unlock(&info->lock); 2619out: 2620 *pagep = page; 2621 *ent = entry; 2622} 2623#endif 2624 2625#else /* !CONFIG_SHMEM */ 2626 2627/* 2628 * tiny-shmem: simple shmemfs and tmpfs using ramfs code 2629 * 2630 * This is intended for small system where the benefits of the full 2631 * shmem code (swap-backed and resource-limited) are outweighed by 2632 * their complexity. On systems without swap this code should be 2633 * effectively equivalent, but much lighter weight. 2634 */ 2635 2636#include <linux/ramfs.h> 2637 2638static struct file_system_type tmpfs_fs_type = { 2639 .name = "tmpfs", 2640 .get_sb = ramfs_get_sb, 2641 .kill_sb = kill_litter_super, 2642}; 2643 2644int __init init_tmpfs(void) 2645{ 2646 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); 2647 2648 shm_mnt = kern_mount(&tmpfs_fs_type); 2649 BUG_ON(IS_ERR(shm_mnt)); 2650 2651 return 0; 2652} 2653 2654int shmem_unuse(swp_entry_t entry, struct page *page) 2655{ 2656 return 0; 2657} 2658 2659int shmem_lock(struct file *file, int lock, struct user_struct *user) 2660{ 2661 return 0; 2662} 2663 2664#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2665/** 2666 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2667 * @inode: the inode to be searched 2668 * @pgoff: the offset to be searched 2669 * @pagep: the pointer for the found page to be stored 2670 * @ent: the pointer for the found swap entry to be stored 2671 * 2672 * If a page is found, refcount of it is incremented. Callers should handle 2673 * these refcount. 2674 */ 2675void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2676 struct page **pagep, swp_entry_t *ent) 2677{ 2678 struct page *page = NULL; 2679 2680 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2681 goto out; 2682 page = find_get_page(inode->i_mapping, pgoff); 2683out: 2684 *pagep = page; 2685 *ent = (swp_entry_t){ .val = 0 }; 2686} 2687#endif 2688 2689#define shmem_vm_ops generic_file_vm_ops 2690#define shmem_file_operations ramfs_file_operations 2691#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) 2692#define shmem_acct_size(flags, size) 0 2693#define shmem_unacct_size(flags, size) do {} while (0) 2694#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE 2695 2696#endif /* CONFIG_SHMEM */ 2697 2698/* common code */ 2699 2700/** 2701 * shmem_file_setup - get an unlinked file living in tmpfs 2702 * @name: name for dentry (to be seen in /proc/<pid>/maps 2703 * @size: size to be set for the file 2704 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size 2705 */ 2706struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) 2707{ 2708 int error; 2709 struct file *file; 2710 struct inode *inode; 2711 struct path path; 2712 struct dentry *root; 2713 struct qstr this; 2714 2715 if (IS_ERR(shm_mnt)) 2716 return (void *)shm_mnt; 2717 2718 if (size < 0 || size > SHMEM_MAX_BYTES) 2719 return ERR_PTR(-EINVAL); 2720 2721 if (shmem_acct_size(flags, size)) 2722 return ERR_PTR(-ENOMEM); 2723 2724 error = -ENOMEM; 2725 this.name = name; 2726 this.len = strlen(name); 2727 this.hash = 0; /* will go */ 2728 root = shm_mnt->mnt_root; 2729 path.dentry = d_alloc(root, &this); 2730 if (!path.dentry) 2731 goto put_memory; 2732 path.mnt = mntget(shm_mnt); 2733 2734 error = -ENOSPC; 2735 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); 2736 if (!inode) 2737 goto put_dentry; 2738 2739 d_instantiate(path.dentry, inode); 2740 inode->i_size = size; 2741 inode->i_nlink = 0; /* It is unlinked */ 2742#ifndef CONFIG_MMU 2743 error = ramfs_nommu_expand_for_mapping(inode, size); 2744 if (error) 2745 goto put_dentry; 2746#endif 2747 2748 error = -ENFILE; 2749 file = alloc_file(&path, FMODE_WRITE | FMODE_READ, 2750 &shmem_file_operations); 2751 if (!file) 2752 goto put_dentry; 2753 2754 return file; 2755 2756put_dentry: 2757 path_put(&path); 2758put_memory: 2759 shmem_unacct_size(flags, size); 2760 return ERR_PTR(error); 2761} 2762EXPORT_SYMBOL_GPL(shmem_file_setup); 2763 2764/** 2765 * shmem_zero_setup - setup a shared anonymous mapping 2766 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2767 */ 2768int shmem_zero_setup(struct vm_area_struct *vma) 2769{ 2770 struct file *file; 2771 loff_t size = vma->vm_end - vma->vm_start; 2772 2773 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2774 if (IS_ERR(file)) 2775 return PTR_ERR(file); 2776 2777 if (vma->vm_file) 2778 fput(vma->vm_file); 2779 vma->vm_file = file; 2780 vma->vm_ops = &shmem_vm_ops; 2781 return 0; 2782} 2783