shmem.c revision 1f895f75dc0881592ef21488aac36cfb2b6ca1e3
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/swap.h> 32 33static struct vfsmount *shm_mnt; 34 35#ifdef CONFIG_SHMEM 36/* 37 * This virtual memory filesystem is heavily based on the ramfs. It 38 * extends ramfs by the ability to use swap and honor resource limits 39 * which makes it a completely usable filesystem. 40 */ 41 42#include <linux/xattr.h> 43#include <linux/exportfs.h> 44#include <linux/posix_acl.h> 45#include <linux/generic_acl.h> 46#include <linux/mman.h> 47#include <linux/string.h> 48#include <linux/slab.h> 49#include <linux/backing-dev.h> 50#include <linux/shmem_fs.h> 51#include <linux/writeback.h> 52#include <linux/blkdev.h> 53#include <linux/security.h> 54#include <linux/swapops.h> 55#include <linux/mempolicy.h> 56#include <linux/namei.h> 57#include <linux/ctype.h> 58#include <linux/migrate.h> 59#include <linux/highmem.h> 60#include <linux/seq_file.h> 61#include <linux/magic.h> 62 63#include <asm/uaccess.h> 64#include <asm/div64.h> 65#include <asm/pgtable.h> 66 67/* 68 * The maximum size of a shmem/tmpfs file is limited by the maximum size of 69 * its triple-indirect swap vector - see illustration at shmem_swp_entry(). 70 * 71 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel, 72 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum 73 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel, 74 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout. 75 * 76 * We use / and * instead of shifts in the definitions below, so that the swap 77 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE. 78 */ 79#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 80#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 81 82#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 83#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT) 84 85#define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE) 86#define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT)) 87 88#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 89#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 90 91/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 92#define SHMEM_PAGEIN VM_READ 93#define SHMEM_TRUNCATE VM_WRITE 94 95/* Definition to limit shmem_truncate's steps between cond_rescheds */ 96#define LATENCY_LIMIT 64 97 98/* Pretend that each entry is of this size in directory's i_size */ 99#define BOGO_DIRENT_SIZE 20 100 101/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 102enum sgp_type { 103 SGP_READ, /* don't exceed i_size, don't allocate page */ 104 SGP_CACHE, /* don't exceed i_size, may allocate page */ 105 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ 106 SGP_WRITE, /* may exceed i_size, may allocate page */ 107}; 108 109#ifdef CONFIG_TMPFS 110static unsigned long shmem_default_max_blocks(void) 111{ 112 return totalram_pages / 2; 113} 114 115static unsigned long shmem_default_max_inodes(void) 116{ 117 return min(totalram_pages - totalhigh_pages, totalram_pages / 2); 118} 119#endif 120 121static int shmem_getpage(struct inode *inode, unsigned long idx, 122 struct page **pagep, enum sgp_type sgp, int *type); 123 124static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 125{ 126 /* 127 * The above definition of ENTRIES_PER_PAGE, and the use of 128 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 129 * might be reconsidered if it ever diverges from PAGE_SIZE. 130 * 131 * Mobility flags are masked out as swap vectors cannot move 132 */ 133 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, 134 PAGE_CACHE_SHIFT-PAGE_SHIFT); 135} 136 137static inline void shmem_dir_free(struct page *page) 138{ 139 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 140} 141 142static struct page **shmem_dir_map(struct page *page) 143{ 144 return (struct page **)kmap_atomic(page, KM_USER0); 145} 146 147static inline void shmem_dir_unmap(struct page **dir) 148{ 149 kunmap_atomic(dir, KM_USER0); 150} 151 152static swp_entry_t *shmem_swp_map(struct page *page) 153{ 154 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 155} 156 157static inline void shmem_swp_balance_unmap(void) 158{ 159 /* 160 * When passing a pointer to an i_direct entry, to code which 161 * also handles indirect entries and so will shmem_swp_unmap, 162 * we must arrange for the preempt count to remain in balance. 163 * What kmap_atomic of a lowmem page does depends on config 164 * and architecture, so pretend to kmap_atomic some lowmem page. 165 */ 166 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 167} 168 169static inline void shmem_swp_unmap(swp_entry_t *entry) 170{ 171 kunmap_atomic(entry, KM_USER1); 172} 173 174static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 175{ 176 return sb->s_fs_info; 177} 178 179/* 180 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 181 * for shared memory and for shared anonymous (/dev/zero) mappings 182 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 183 * consistent with the pre-accounting of private mappings ... 184 */ 185static inline int shmem_acct_size(unsigned long flags, loff_t size) 186{ 187 return (flags & VM_NORESERVE) ? 188 0 : security_vm_enough_memory_kern(VM_ACCT(size)); 189} 190 191static inline void shmem_unacct_size(unsigned long flags, loff_t size) 192{ 193 if (!(flags & VM_NORESERVE)) 194 vm_unacct_memory(VM_ACCT(size)); 195} 196 197/* 198 * ... whereas tmpfs objects are accounted incrementally as 199 * pages are allocated, in order to allow huge sparse files. 200 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 201 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 202 */ 203static inline int shmem_acct_block(unsigned long flags) 204{ 205 return (flags & VM_NORESERVE) ? 206 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0; 207} 208 209static inline void shmem_unacct_blocks(unsigned long flags, long pages) 210{ 211 if (flags & VM_NORESERVE) 212 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 213} 214 215static const struct super_operations shmem_ops; 216static const struct address_space_operations shmem_aops; 217static const struct file_operations shmem_file_operations; 218static const struct inode_operations shmem_inode_operations; 219static const struct inode_operations shmem_dir_inode_operations; 220static const struct inode_operations shmem_special_inode_operations; 221static const struct vm_operations_struct shmem_vm_ops; 222 223static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 224 .ra_pages = 0, /* No readahead */ 225 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, 226 .unplug_io_fn = default_unplug_io_fn, 227}; 228 229static LIST_HEAD(shmem_swaplist); 230static DEFINE_MUTEX(shmem_swaplist_mutex); 231 232static void shmem_free_blocks(struct inode *inode, long pages) 233{ 234 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 235 if (sbinfo->max_blocks) { 236 spin_lock(&sbinfo->stat_lock); 237 sbinfo->free_blocks += pages; 238 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 239 spin_unlock(&sbinfo->stat_lock); 240 } 241} 242 243static int shmem_reserve_inode(struct super_block *sb) 244{ 245 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 246 if (sbinfo->max_inodes) { 247 spin_lock(&sbinfo->stat_lock); 248 if (!sbinfo->free_inodes) { 249 spin_unlock(&sbinfo->stat_lock); 250 return -ENOSPC; 251 } 252 sbinfo->free_inodes--; 253 spin_unlock(&sbinfo->stat_lock); 254 } 255 return 0; 256} 257 258static void shmem_free_inode(struct super_block *sb) 259{ 260 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 261 if (sbinfo->max_inodes) { 262 spin_lock(&sbinfo->stat_lock); 263 sbinfo->free_inodes++; 264 spin_unlock(&sbinfo->stat_lock); 265 } 266} 267 268/** 269 * shmem_recalc_inode - recalculate the size of an inode 270 * @inode: inode to recalc 271 * 272 * We have to calculate the free blocks since the mm can drop 273 * undirtied hole pages behind our back. 274 * 275 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 276 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 277 * 278 * It has to be called with the spinlock held. 279 */ 280static void shmem_recalc_inode(struct inode *inode) 281{ 282 struct shmem_inode_info *info = SHMEM_I(inode); 283 long freed; 284 285 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 286 if (freed > 0) { 287 info->alloced -= freed; 288 shmem_unacct_blocks(info->flags, freed); 289 shmem_free_blocks(inode, freed); 290 } 291} 292 293/** 294 * shmem_swp_entry - find the swap vector position in the info structure 295 * @info: info structure for the inode 296 * @index: index of the page to find 297 * @page: optional page to add to the structure. Has to be preset to 298 * all zeros 299 * 300 * If there is no space allocated yet it will return NULL when 301 * page is NULL, else it will use the page for the needed block, 302 * setting it to NULL on return to indicate that it has been used. 303 * 304 * The swap vector is organized the following way: 305 * 306 * There are SHMEM_NR_DIRECT entries directly stored in the 307 * shmem_inode_info structure. So small files do not need an addional 308 * allocation. 309 * 310 * For pages with index > SHMEM_NR_DIRECT there is the pointer 311 * i_indirect which points to a page which holds in the first half 312 * doubly indirect blocks, in the second half triple indirect blocks: 313 * 314 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 315 * following layout (for SHMEM_NR_DIRECT == 16): 316 * 317 * i_indirect -> dir --> 16-19 318 * | +-> 20-23 319 * | 320 * +-->dir2 --> 24-27 321 * | +-> 28-31 322 * | +-> 32-35 323 * | +-> 36-39 324 * | 325 * +-->dir3 --> 40-43 326 * +-> 44-47 327 * +-> 48-51 328 * +-> 52-55 329 */ 330static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 331{ 332 unsigned long offset; 333 struct page **dir; 334 struct page *subdir; 335 336 if (index < SHMEM_NR_DIRECT) { 337 shmem_swp_balance_unmap(); 338 return info->i_direct+index; 339 } 340 if (!info->i_indirect) { 341 if (page) { 342 info->i_indirect = *page; 343 *page = NULL; 344 } 345 return NULL; /* need another page */ 346 } 347 348 index -= SHMEM_NR_DIRECT; 349 offset = index % ENTRIES_PER_PAGE; 350 index /= ENTRIES_PER_PAGE; 351 dir = shmem_dir_map(info->i_indirect); 352 353 if (index >= ENTRIES_PER_PAGE/2) { 354 index -= ENTRIES_PER_PAGE/2; 355 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 356 index %= ENTRIES_PER_PAGE; 357 subdir = *dir; 358 if (!subdir) { 359 if (page) { 360 *dir = *page; 361 *page = NULL; 362 } 363 shmem_dir_unmap(dir); 364 return NULL; /* need another page */ 365 } 366 shmem_dir_unmap(dir); 367 dir = shmem_dir_map(subdir); 368 } 369 370 dir += index; 371 subdir = *dir; 372 if (!subdir) { 373 if (!page || !(subdir = *page)) { 374 shmem_dir_unmap(dir); 375 return NULL; /* need a page */ 376 } 377 *dir = subdir; 378 *page = NULL; 379 } 380 shmem_dir_unmap(dir); 381 return shmem_swp_map(subdir) + offset; 382} 383 384static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 385{ 386 long incdec = value? 1: -1; 387 388 entry->val = value; 389 info->swapped += incdec; 390 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 391 struct page *page = kmap_atomic_to_page(entry); 392 set_page_private(page, page_private(page) + incdec); 393 } 394} 395 396/** 397 * shmem_swp_alloc - get the position of the swap entry for the page. 398 * @info: info structure for the inode 399 * @index: index of the page to find 400 * @sgp: check and recheck i_size? skip allocation? 401 * 402 * If the entry does not exist, allocate it. 403 */ 404static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 405{ 406 struct inode *inode = &info->vfs_inode; 407 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 408 struct page *page = NULL; 409 swp_entry_t *entry; 410 411 if (sgp != SGP_WRITE && 412 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 413 return ERR_PTR(-EINVAL); 414 415 while (!(entry = shmem_swp_entry(info, index, &page))) { 416 if (sgp == SGP_READ) 417 return shmem_swp_map(ZERO_PAGE(0)); 418 /* 419 * Test free_blocks against 1 not 0, since we have 1 data 420 * page (and perhaps indirect index pages) yet to allocate: 421 * a waste to allocate index if we cannot allocate data. 422 */ 423 if (sbinfo->max_blocks) { 424 spin_lock(&sbinfo->stat_lock); 425 if (sbinfo->free_blocks <= 1) { 426 spin_unlock(&sbinfo->stat_lock); 427 return ERR_PTR(-ENOSPC); 428 } 429 sbinfo->free_blocks--; 430 inode->i_blocks += BLOCKS_PER_PAGE; 431 spin_unlock(&sbinfo->stat_lock); 432 } 433 434 spin_unlock(&info->lock); 435 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); 436 spin_lock(&info->lock); 437 438 if (!page) { 439 shmem_free_blocks(inode, 1); 440 return ERR_PTR(-ENOMEM); 441 } 442 if (sgp != SGP_WRITE && 443 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 444 entry = ERR_PTR(-EINVAL); 445 break; 446 } 447 if (info->next_index <= index) 448 info->next_index = index + 1; 449 } 450 if (page) { 451 /* another task gave its page, or truncated the file */ 452 shmem_free_blocks(inode, 1); 453 shmem_dir_free(page); 454 } 455 if (info->next_index <= index && !IS_ERR(entry)) 456 info->next_index = index + 1; 457 return entry; 458} 459 460/** 461 * shmem_free_swp - free some swap entries in a directory 462 * @dir: pointer to the directory 463 * @edir: pointer after last entry of the directory 464 * @punch_lock: pointer to spinlock when needed for the holepunch case 465 */ 466static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, 467 spinlock_t *punch_lock) 468{ 469 spinlock_t *punch_unlock = NULL; 470 swp_entry_t *ptr; 471 int freed = 0; 472 473 for (ptr = dir; ptr < edir; ptr++) { 474 if (ptr->val) { 475 if (unlikely(punch_lock)) { 476 punch_unlock = punch_lock; 477 punch_lock = NULL; 478 spin_lock(punch_unlock); 479 if (!ptr->val) 480 continue; 481 } 482 free_swap_and_cache(*ptr); 483 *ptr = (swp_entry_t){0}; 484 freed++; 485 } 486 } 487 if (punch_unlock) 488 spin_unlock(punch_unlock); 489 return freed; 490} 491 492static int shmem_map_and_free_swp(struct page *subdir, int offset, 493 int limit, struct page ***dir, spinlock_t *punch_lock) 494{ 495 swp_entry_t *ptr; 496 int freed = 0; 497 498 ptr = shmem_swp_map(subdir); 499 for (; offset < limit; offset += LATENCY_LIMIT) { 500 int size = limit - offset; 501 if (size > LATENCY_LIMIT) 502 size = LATENCY_LIMIT; 503 freed += shmem_free_swp(ptr+offset, ptr+offset+size, 504 punch_lock); 505 if (need_resched()) { 506 shmem_swp_unmap(ptr); 507 if (*dir) { 508 shmem_dir_unmap(*dir); 509 *dir = NULL; 510 } 511 cond_resched(); 512 ptr = shmem_swp_map(subdir); 513 } 514 } 515 shmem_swp_unmap(ptr); 516 return freed; 517} 518 519static void shmem_free_pages(struct list_head *next) 520{ 521 struct page *page; 522 int freed = 0; 523 524 do { 525 page = container_of(next, struct page, lru); 526 next = next->next; 527 shmem_dir_free(page); 528 freed++; 529 if (freed >= LATENCY_LIMIT) { 530 cond_resched(); 531 freed = 0; 532 } 533 } while (next); 534} 535 536static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 537{ 538 struct shmem_inode_info *info = SHMEM_I(inode); 539 unsigned long idx; 540 unsigned long size; 541 unsigned long limit; 542 unsigned long stage; 543 unsigned long diroff; 544 struct page **dir; 545 struct page *topdir; 546 struct page *middir; 547 struct page *subdir; 548 swp_entry_t *ptr; 549 LIST_HEAD(pages_to_free); 550 long nr_pages_to_free = 0; 551 long nr_swaps_freed = 0; 552 int offset; 553 int freed; 554 int punch_hole; 555 spinlock_t *needs_lock; 556 spinlock_t *punch_lock; 557 unsigned long upper_limit; 558 559 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 560 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 561 if (idx >= info->next_index) 562 return; 563 564 spin_lock(&info->lock); 565 info->flags |= SHMEM_TRUNCATE; 566 if (likely(end == (loff_t) -1)) { 567 limit = info->next_index; 568 upper_limit = SHMEM_MAX_INDEX; 569 info->next_index = idx; 570 needs_lock = NULL; 571 punch_hole = 0; 572 } else { 573 if (end + 1 >= inode->i_size) { /* we may free a little more */ 574 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> 575 PAGE_CACHE_SHIFT; 576 upper_limit = SHMEM_MAX_INDEX; 577 } else { 578 limit = (end + 1) >> PAGE_CACHE_SHIFT; 579 upper_limit = limit; 580 } 581 needs_lock = &info->lock; 582 punch_hole = 1; 583 } 584 585 topdir = info->i_indirect; 586 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 587 info->i_indirect = NULL; 588 nr_pages_to_free++; 589 list_add(&topdir->lru, &pages_to_free); 590 } 591 spin_unlock(&info->lock); 592 593 if (info->swapped && idx < SHMEM_NR_DIRECT) { 594 ptr = info->i_direct; 595 size = limit; 596 if (size > SHMEM_NR_DIRECT) 597 size = SHMEM_NR_DIRECT; 598 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); 599 } 600 601 /* 602 * If there are no indirect blocks or we are punching a hole 603 * below indirect blocks, nothing to be done. 604 */ 605 if (!topdir || limit <= SHMEM_NR_DIRECT) 606 goto done2; 607 608 /* 609 * The truncation case has already dropped info->lock, and we're safe 610 * because i_size and next_index have already been lowered, preventing 611 * access beyond. But in the punch_hole case, we still need to take 612 * the lock when updating the swap directory, because there might be 613 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or 614 * shmem_writepage. However, whenever we find we can remove a whole 615 * directory page (not at the misaligned start or end of the range), 616 * we first NULLify its pointer in the level above, and then have no 617 * need to take the lock when updating its contents: needs_lock and 618 * punch_lock (either pointing to info->lock or NULL) manage this. 619 */ 620 621 upper_limit -= SHMEM_NR_DIRECT; 622 limit -= SHMEM_NR_DIRECT; 623 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 624 offset = idx % ENTRIES_PER_PAGE; 625 idx -= offset; 626 627 dir = shmem_dir_map(topdir); 628 stage = ENTRIES_PER_PAGEPAGE/2; 629 if (idx < ENTRIES_PER_PAGEPAGE/2) { 630 middir = topdir; 631 diroff = idx/ENTRIES_PER_PAGE; 632 } else { 633 dir += ENTRIES_PER_PAGE/2; 634 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 635 while (stage <= idx) 636 stage += ENTRIES_PER_PAGEPAGE; 637 middir = *dir; 638 if (*dir) { 639 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 640 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 641 if (!diroff && !offset && upper_limit >= stage) { 642 if (needs_lock) { 643 spin_lock(needs_lock); 644 *dir = NULL; 645 spin_unlock(needs_lock); 646 needs_lock = NULL; 647 } else 648 *dir = NULL; 649 nr_pages_to_free++; 650 list_add(&middir->lru, &pages_to_free); 651 } 652 shmem_dir_unmap(dir); 653 dir = shmem_dir_map(middir); 654 } else { 655 diroff = 0; 656 offset = 0; 657 idx = stage; 658 } 659 } 660 661 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 662 if (unlikely(idx == stage)) { 663 shmem_dir_unmap(dir); 664 dir = shmem_dir_map(topdir) + 665 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 666 while (!*dir) { 667 dir++; 668 idx += ENTRIES_PER_PAGEPAGE; 669 if (idx >= limit) 670 goto done1; 671 } 672 stage = idx + ENTRIES_PER_PAGEPAGE; 673 middir = *dir; 674 if (punch_hole) 675 needs_lock = &info->lock; 676 if (upper_limit >= stage) { 677 if (needs_lock) { 678 spin_lock(needs_lock); 679 *dir = NULL; 680 spin_unlock(needs_lock); 681 needs_lock = NULL; 682 } else 683 *dir = NULL; 684 nr_pages_to_free++; 685 list_add(&middir->lru, &pages_to_free); 686 } 687 shmem_dir_unmap(dir); 688 cond_resched(); 689 dir = shmem_dir_map(middir); 690 diroff = 0; 691 } 692 punch_lock = needs_lock; 693 subdir = dir[diroff]; 694 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { 695 if (needs_lock) { 696 spin_lock(needs_lock); 697 dir[diroff] = NULL; 698 spin_unlock(needs_lock); 699 punch_lock = NULL; 700 } else 701 dir[diroff] = NULL; 702 nr_pages_to_free++; 703 list_add(&subdir->lru, &pages_to_free); 704 } 705 if (subdir && page_private(subdir) /* has swap entries */) { 706 size = limit - idx; 707 if (size > ENTRIES_PER_PAGE) 708 size = ENTRIES_PER_PAGE; 709 freed = shmem_map_and_free_swp(subdir, 710 offset, size, &dir, punch_lock); 711 if (!dir) 712 dir = shmem_dir_map(middir); 713 nr_swaps_freed += freed; 714 if (offset || punch_lock) { 715 spin_lock(&info->lock); 716 set_page_private(subdir, 717 page_private(subdir) - freed); 718 spin_unlock(&info->lock); 719 } else 720 BUG_ON(page_private(subdir) != freed); 721 } 722 offset = 0; 723 } 724done1: 725 shmem_dir_unmap(dir); 726done2: 727 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 728 /* 729 * Call truncate_inode_pages again: racing shmem_unuse_inode 730 * may have swizzled a page in from swap since 731 * truncate_pagecache or generic_delete_inode did it, before we 732 * lowered next_index. Also, though shmem_getpage checks 733 * i_size before adding to cache, no recheck after: so fix the 734 * narrow window there too. 735 * 736 * Recalling truncate_inode_pages_range and unmap_mapping_range 737 * every time for punch_hole (which never got a chance to clear 738 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 739 * yet hardly ever necessary: try to optimize them out later. 740 */ 741 truncate_inode_pages_range(inode->i_mapping, start, end); 742 if (punch_hole) 743 unmap_mapping_range(inode->i_mapping, start, 744 end - start, 1); 745 } 746 747 spin_lock(&info->lock); 748 info->flags &= ~SHMEM_TRUNCATE; 749 info->swapped -= nr_swaps_freed; 750 if (nr_pages_to_free) 751 shmem_free_blocks(inode, nr_pages_to_free); 752 shmem_recalc_inode(inode); 753 spin_unlock(&info->lock); 754 755 /* 756 * Empty swap vector directory pages to be freed? 757 */ 758 if (!list_empty(&pages_to_free)) { 759 pages_to_free.prev->next = NULL; 760 shmem_free_pages(pages_to_free.next); 761 } 762} 763 764static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 765{ 766 struct inode *inode = dentry->d_inode; 767 loff_t newsize = attr->ia_size; 768 int error; 769 770 error = inode_change_ok(inode, attr); 771 if (error) 772 return error; 773 774 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE) 775 && newsize != inode->i_size) { 776 struct page *page = NULL; 777 778 if (newsize < inode->i_size) { 779 /* 780 * If truncating down to a partial page, then 781 * if that page is already allocated, hold it 782 * in memory until the truncation is over, so 783 * truncate_partial_page cannnot miss it were 784 * it assigned to swap. 785 */ 786 if (newsize & (PAGE_CACHE_SIZE-1)) { 787 (void) shmem_getpage(inode, 788 newsize >> PAGE_CACHE_SHIFT, 789 &page, SGP_READ, NULL); 790 if (page) 791 unlock_page(page); 792 } 793 /* 794 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 795 * detect if any pages might have been added to cache 796 * after truncate_inode_pages. But we needn't bother 797 * if it's being fully truncated to zero-length: the 798 * nrpages check is efficient enough in that case. 799 */ 800 if (newsize) { 801 struct shmem_inode_info *info = SHMEM_I(inode); 802 spin_lock(&info->lock); 803 info->flags &= ~SHMEM_PAGEIN; 804 spin_unlock(&info->lock); 805 } 806 } 807 808 /* XXX(truncate): truncate_setsize should be called last */ 809 truncate_setsize(inode, newsize); 810 if (page) 811 page_cache_release(page); 812 shmem_truncate_range(inode, newsize, (loff_t)-1); 813 } 814 815 setattr_copy(inode, attr); 816#ifdef CONFIG_TMPFS_POSIX_ACL 817 if (attr->ia_valid & ATTR_MODE) 818 error = generic_acl_chmod(inode); 819#endif 820 return error; 821} 822 823static void shmem_evict_inode(struct inode *inode) 824{ 825 struct shmem_inode_info *info = SHMEM_I(inode); 826 827 if (inode->i_mapping->a_ops == &shmem_aops) { 828 truncate_inode_pages(inode->i_mapping, 0); 829 shmem_unacct_size(info->flags, inode->i_size); 830 inode->i_size = 0; 831 shmem_truncate_range(inode, 0, (loff_t)-1); 832 if (!list_empty(&info->swaplist)) { 833 mutex_lock(&shmem_swaplist_mutex); 834 list_del_init(&info->swaplist); 835 mutex_unlock(&shmem_swaplist_mutex); 836 } 837 } 838 BUG_ON(inode->i_blocks); 839 shmem_free_inode(inode->i_sb); 840 end_writeback(inode); 841} 842 843static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 844{ 845 swp_entry_t *ptr; 846 847 for (ptr = dir; ptr < edir; ptr++) { 848 if (ptr->val == entry.val) 849 return ptr - dir; 850 } 851 return -1; 852} 853 854static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 855{ 856 struct inode *inode; 857 unsigned long idx; 858 unsigned long size; 859 unsigned long limit; 860 unsigned long stage; 861 struct page **dir; 862 struct page *subdir; 863 swp_entry_t *ptr; 864 int offset; 865 int error; 866 867 idx = 0; 868 ptr = info->i_direct; 869 spin_lock(&info->lock); 870 if (!info->swapped) { 871 list_del_init(&info->swaplist); 872 goto lost2; 873 } 874 limit = info->next_index; 875 size = limit; 876 if (size > SHMEM_NR_DIRECT) 877 size = SHMEM_NR_DIRECT; 878 offset = shmem_find_swp(entry, ptr, ptr+size); 879 if (offset >= 0) 880 goto found; 881 if (!info->i_indirect) 882 goto lost2; 883 884 dir = shmem_dir_map(info->i_indirect); 885 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 886 887 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 888 if (unlikely(idx == stage)) { 889 shmem_dir_unmap(dir-1); 890 if (cond_resched_lock(&info->lock)) { 891 /* check it has not been truncated */ 892 if (limit > info->next_index) { 893 limit = info->next_index; 894 if (idx >= limit) 895 goto lost2; 896 } 897 } 898 dir = shmem_dir_map(info->i_indirect) + 899 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 900 while (!*dir) { 901 dir++; 902 idx += ENTRIES_PER_PAGEPAGE; 903 if (idx >= limit) 904 goto lost1; 905 } 906 stage = idx + ENTRIES_PER_PAGEPAGE; 907 subdir = *dir; 908 shmem_dir_unmap(dir); 909 dir = shmem_dir_map(subdir); 910 } 911 subdir = *dir; 912 if (subdir && page_private(subdir)) { 913 ptr = shmem_swp_map(subdir); 914 size = limit - idx; 915 if (size > ENTRIES_PER_PAGE) 916 size = ENTRIES_PER_PAGE; 917 offset = shmem_find_swp(entry, ptr, ptr+size); 918 shmem_swp_unmap(ptr); 919 if (offset >= 0) { 920 shmem_dir_unmap(dir); 921 goto found; 922 } 923 } 924 } 925lost1: 926 shmem_dir_unmap(dir-1); 927lost2: 928 spin_unlock(&info->lock); 929 return 0; 930found: 931 idx += offset; 932 inode = igrab(&info->vfs_inode); 933 spin_unlock(&info->lock); 934 935 /* 936 * Move _head_ to start search for next from here. 937 * But be careful: shmem_evict_inode checks list_empty without taking 938 * mutex, and there's an instant in list_move_tail when info->swaplist 939 * would appear empty, if it were the only one on shmem_swaplist. We 940 * could avoid doing it if inode NULL; or use this minor optimization. 941 */ 942 if (shmem_swaplist.next != &info->swaplist) 943 list_move_tail(&shmem_swaplist, &info->swaplist); 944 mutex_unlock(&shmem_swaplist_mutex); 945 946 error = 1; 947 if (!inode) 948 goto out; 949 /* 950 * Charge page using GFP_KERNEL while we can wait. 951 * Charged back to the user(not to caller) when swap account is used. 952 * add_to_page_cache() will be called with GFP_NOWAIT. 953 */ 954 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); 955 if (error) 956 goto out; 957 error = radix_tree_preload(GFP_KERNEL); 958 if (error) { 959 mem_cgroup_uncharge_cache_page(page); 960 goto out; 961 } 962 error = 1; 963 964 spin_lock(&info->lock); 965 ptr = shmem_swp_entry(info, idx, NULL); 966 if (ptr && ptr->val == entry.val) { 967 error = add_to_page_cache_locked(page, inode->i_mapping, 968 idx, GFP_NOWAIT); 969 /* does mem_cgroup_uncharge_cache_page on error */ 970 } else /* we must compensate for our precharge above */ 971 mem_cgroup_uncharge_cache_page(page); 972 973 if (error == -EEXIST) { 974 struct page *filepage = find_get_page(inode->i_mapping, idx); 975 error = 1; 976 if (filepage) { 977 /* 978 * There might be a more uptodate page coming down 979 * from a stacked writepage: forget our swappage if so. 980 */ 981 if (PageUptodate(filepage)) 982 error = 0; 983 page_cache_release(filepage); 984 } 985 } 986 if (!error) { 987 delete_from_swap_cache(page); 988 set_page_dirty(page); 989 info->flags |= SHMEM_PAGEIN; 990 shmem_swp_set(info, ptr, 0); 991 swap_free(entry); 992 error = 1; /* not an error, but entry was found */ 993 } 994 if (ptr) 995 shmem_swp_unmap(ptr); 996 spin_unlock(&info->lock); 997 radix_tree_preload_end(); 998out: 999 unlock_page(page); 1000 page_cache_release(page); 1001 iput(inode); /* allows for NULL */ 1002 return error; 1003} 1004 1005/* 1006 * shmem_unuse() search for an eventually swapped out shmem page. 1007 */ 1008int shmem_unuse(swp_entry_t entry, struct page *page) 1009{ 1010 struct list_head *p, *next; 1011 struct shmem_inode_info *info; 1012 int found = 0; 1013 1014 mutex_lock(&shmem_swaplist_mutex); 1015 list_for_each_safe(p, next, &shmem_swaplist) { 1016 info = list_entry(p, struct shmem_inode_info, swaplist); 1017 found = shmem_unuse_inode(info, entry, page); 1018 cond_resched(); 1019 if (found) 1020 goto out; 1021 } 1022 mutex_unlock(&shmem_swaplist_mutex); 1023 /* 1024 * Can some race bring us here? We've been holding page lock, 1025 * so I think not; but would rather try again later than BUG() 1026 */ 1027 unlock_page(page); 1028 page_cache_release(page); 1029out: 1030 return (found < 0) ? found : 0; 1031} 1032 1033/* 1034 * Move the page from the page cache to the swap cache. 1035 */ 1036static int shmem_writepage(struct page *page, struct writeback_control *wbc) 1037{ 1038 struct shmem_inode_info *info; 1039 swp_entry_t *entry, swap; 1040 struct address_space *mapping; 1041 unsigned long index; 1042 struct inode *inode; 1043 1044 BUG_ON(!PageLocked(page)); 1045 mapping = page->mapping; 1046 index = page->index; 1047 inode = mapping->host; 1048 info = SHMEM_I(inode); 1049 if (info->flags & VM_LOCKED) 1050 goto redirty; 1051 if (!total_swap_pages) 1052 goto redirty; 1053 1054 /* 1055 * shmem_backing_dev_info's capabilities prevent regular writeback or 1056 * sync from ever calling shmem_writepage; but a stacking filesystem 1057 * may use the ->writepage of its underlying filesystem, in which case 1058 * tmpfs should write out to swap only in response to memory pressure, 1059 * and not for the writeback threads or sync. However, in those cases, 1060 * we do still want to check if there's a redundant swappage to be 1061 * discarded. 1062 */ 1063 if (wbc->for_reclaim) 1064 swap = get_swap_page(); 1065 else 1066 swap.val = 0; 1067 1068 spin_lock(&info->lock); 1069 if (index >= info->next_index) { 1070 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1071 goto unlock; 1072 } 1073 entry = shmem_swp_entry(info, index, NULL); 1074 if (entry->val) { 1075 /* 1076 * The more uptodate page coming down from a stacked 1077 * writepage should replace our old swappage. 1078 */ 1079 free_swap_and_cache(*entry); 1080 shmem_swp_set(info, entry, 0); 1081 } 1082 shmem_recalc_inode(inode); 1083 1084 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1085 remove_from_page_cache(page); 1086 shmem_swp_set(info, entry, swap.val); 1087 shmem_swp_unmap(entry); 1088 if (list_empty(&info->swaplist)) 1089 inode = igrab(inode); 1090 else 1091 inode = NULL; 1092 spin_unlock(&info->lock); 1093 swap_shmem_alloc(swap); 1094 BUG_ON(page_mapped(page)); 1095 page_cache_release(page); /* pagecache ref */ 1096 swap_writepage(page, wbc); 1097 if (inode) { 1098 mutex_lock(&shmem_swaplist_mutex); 1099 /* move instead of add in case we're racing */ 1100 list_move_tail(&info->swaplist, &shmem_swaplist); 1101 mutex_unlock(&shmem_swaplist_mutex); 1102 iput(inode); 1103 } 1104 return 0; 1105 } 1106 1107 shmem_swp_unmap(entry); 1108unlock: 1109 spin_unlock(&info->lock); 1110 /* 1111 * add_to_swap_cache() doesn't return -EEXIST, so we can safely 1112 * clear SWAP_HAS_CACHE flag. 1113 */ 1114 swapcache_free(swap, NULL); 1115redirty: 1116 set_page_dirty(page); 1117 if (wbc->for_reclaim) 1118 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1119 unlock_page(page); 1120 return 0; 1121} 1122 1123#ifdef CONFIG_NUMA 1124#ifdef CONFIG_TMPFS 1125static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) 1126{ 1127 char buffer[64]; 1128 1129 if (!mpol || mpol->mode == MPOL_DEFAULT) 1130 return; /* show nothing */ 1131 1132 mpol_to_str(buffer, sizeof(buffer), mpol, 1); 1133 1134 seq_printf(seq, ",mpol=%s", buffer); 1135} 1136 1137static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1138{ 1139 struct mempolicy *mpol = NULL; 1140 if (sbinfo->mpol) { 1141 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ 1142 mpol = sbinfo->mpol; 1143 mpol_get(mpol); 1144 spin_unlock(&sbinfo->stat_lock); 1145 } 1146 return mpol; 1147} 1148#endif /* CONFIG_TMPFS */ 1149 1150static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1151 struct shmem_inode_info *info, unsigned long idx) 1152{ 1153 struct mempolicy mpol, *spol; 1154 struct vm_area_struct pvma; 1155 struct page *page; 1156 1157 spol = mpol_cond_copy(&mpol, 1158 mpol_shared_policy_lookup(&info->policy, idx)); 1159 1160 /* Create a pseudo vma that just contains the policy */ 1161 pvma.vm_start = 0; 1162 pvma.vm_pgoff = idx; 1163 pvma.vm_ops = NULL; 1164 pvma.vm_policy = spol; 1165 page = swapin_readahead(entry, gfp, &pvma, 0); 1166 return page; 1167} 1168 1169static struct page *shmem_alloc_page(gfp_t gfp, 1170 struct shmem_inode_info *info, unsigned long idx) 1171{ 1172 struct vm_area_struct pvma; 1173 1174 /* Create a pseudo vma that just contains the policy */ 1175 pvma.vm_start = 0; 1176 pvma.vm_pgoff = idx; 1177 pvma.vm_ops = NULL; 1178 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1179 1180 /* 1181 * alloc_page_vma() will drop the shared policy reference 1182 */ 1183 return alloc_page_vma(gfp, &pvma, 0); 1184} 1185#else /* !CONFIG_NUMA */ 1186#ifdef CONFIG_TMPFS 1187static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) 1188{ 1189} 1190#endif /* CONFIG_TMPFS */ 1191 1192static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1193 struct shmem_inode_info *info, unsigned long idx) 1194{ 1195 return swapin_readahead(entry, gfp, NULL, 0); 1196} 1197 1198static inline struct page *shmem_alloc_page(gfp_t gfp, 1199 struct shmem_inode_info *info, unsigned long idx) 1200{ 1201 return alloc_page(gfp); 1202} 1203#endif /* CONFIG_NUMA */ 1204 1205#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) 1206static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1207{ 1208 return NULL; 1209} 1210#endif 1211 1212/* 1213 * shmem_getpage - either get the page from swap or allocate a new one 1214 * 1215 * If we allocate a new one we do not mark it dirty. That's up to the 1216 * vm. If we swap it in we mark it dirty since we also free the swap 1217 * entry since a page cannot live in both the swap and page cache 1218 */ 1219static int shmem_getpage(struct inode *inode, unsigned long idx, 1220 struct page **pagep, enum sgp_type sgp, int *type) 1221{ 1222 struct address_space *mapping = inode->i_mapping; 1223 struct shmem_inode_info *info = SHMEM_I(inode); 1224 struct shmem_sb_info *sbinfo; 1225 struct page *filepage = *pagep; 1226 struct page *swappage; 1227 swp_entry_t *entry; 1228 swp_entry_t swap; 1229 gfp_t gfp; 1230 int error; 1231 1232 if (idx >= SHMEM_MAX_INDEX) 1233 return -EFBIG; 1234 1235 if (type) 1236 *type = 0; 1237 1238 /* 1239 * Normally, filepage is NULL on entry, and either found 1240 * uptodate immediately, or allocated and zeroed, or read 1241 * in under swappage, which is then assigned to filepage. 1242 * But shmem_readpage (required for splice) passes in a locked 1243 * filepage, which may be found not uptodate by other callers 1244 * too, and may need to be copied from the swappage read in. 1245 */ 1246repeat: 1247 if (!filepage) 1248 filepage = find_lock_page(mapping, idx); 1249 if (filepage && PageUptodate(filepage)) 1250 goto done; 1251 error = 0; 1252 gfp = mapping_gfp_mask(mapping); 1253 if (!filepage) { 1254 /* 1255 * Try to preload while we can wait, to not make a habit of 1256 * draining atomic reserves; but don't latch on to this cpu. 1257 */ 1258 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1259 if (error) 1260 goto failed; 1261 radix_tree_preload_end(); 1262 } 1263 1264 spin_lock(&info->lock); 1265 shmem_recalc_inode(inode); 1266 entry = shmem_swp_alloc(info, idx, sgp); 1267 if (IS_ERR(entry)) { 1268 spin_unlock(&info->lock); 1269 error = PTR_ERR(entry); 1270 goto failed; 1271 } 1272 swap = *entry; 1273 1274 if (swap.val) { 1275 /* Look it up and read it in.. */ 1276 swappage = lookup_swap_cache(swap); 1277 if (!swappage) { 1278 shmem_swp_unmap(entry); 1279 /* here we actually do the io */ 1280 if (type && !(*type & VM_FAULT_MAJOR)) { 1281 __count_vm_event(PGMAJFAULT); 1282 *type |= VM_FAULT_MAJOR; 1283 } 1284 spin_unlock(&info->lock); 1285 swappage = shmem_swapin(swap, gfp, info, idx); 1286 if (!swappage) { 1287 spin_lock(&info->lock); 1288 entry = shmem_swp_alloc(info, idx, sgp); 1289 if (IS_ERR(entry)) 1290 error = PTR_ERR(entry); 1291 else { 1292 if (entry->val == swap.val) 1293 error = -ENOMEM; 1294 shmem_swp_unmap(entry); 1295 } 1296 spin_unlock(&info->lock); 1297 if (error) 1298 goto failed; 1299 goto repeat; 1300 } 1301 wait_on_page_locked(swappage); 1302 page_cache_release(swappage); 1303 goto repeat; 1304 } 1305 1306 /* We have to do this with page locked to prevent races */ 1307 if (!trylock_page(swappage)) { 1308 shmem_swp_unmap(entry); 1309 spin_unlock(&info->lock); 1310 wait_on_page_locked(swappage); 1311 page_cache_release(swappage); 1312 goto repeat; 1313 } 1314 if (PageWriteback(swappage)) { 1315 shmem_swp_unmap(entry); 1316 spin_unlock(&info->lock); 1317 wait_on_page_writeback(swappage); 1318 unlock_page(swappage); 1319 page_cache_release(swappage); 1320 goto repeat; 1321 } 1322 if (!PageUptodate(swappage)) { 1323 shmem_swp_unmap(entry); 1324 spin_unlock(&info->lock); 1325 unlock_page(swappage); 1326 page_cache_release(swappage); 1327 error = -EIO; 1328 goto failed; 1329 } 1330 1331 if (filepage) { 1332 shmem_swp_set(info, entry, 0); 1333 shmem_swp_unmap(entry); 1334 delete_from_swap_cache(swappage); 1335 spin_unlock(&info->lock); 1336 copy_highpage(filepage, swappage); 1337 unlock_page(swappage); 1338 page_cache_release(swappage); 1339 flush_dcache_page(filepage); 1340 SetPageUptodate(filepage); 1341 set_page_dirty(filepage); 1342 swap_free(swap); 1343 } else if (!(error = add_to_page_cache_locked(swappage, mapping, 1344 idx, GFP_NOWAIT))) { 1345 info->flags |= SHMEM_PAGEIN; 1346 shmem_swp_set(info, entry, 0); 1347 shmem_swp_unmap(entry); 1348 delete_from_swap_cache(swappage); 1349 spin_unlock(&info->lock); 1350 filepage = swappage; 1351 set_page_dirty(filepage); 1352 swap_free(swap); 1353 } else { 1354 shmem_swp_unmap(entry); 1355 spin_unlock(&info->lock); 1356 if (error == -ENOMEM) { 1357 /* 1358 * reclaim from proper memory cgroup and 1359 * call memcg's OOM if needed. 1360 */ 1361 error = mem_cgroup_shmem_charge_fallback( 1362 swappage, 1363 current->mm, 1364 gfp); 1365 if (error) { 1366 unlock_page(swappage); 1367 page_cache_release(swappage); 1368 goto failed; 1369 } 1370 } 1371 unlock_page(swappage); 1372 page_cache_release(swappage); 1373 goto repeat; 1374 } 1375 } else if (sgp == SGP_READ && !filepage) { 1376 shmem_swp_unmap(entry); 1377 filepage = find_get_page(mapping, idx); 1378 if (filepage && 1379 (!PageUptodate(filepage) || !trylock_page(filepage))) { 1380 spin_unlock(&info->lock); 1381 wait_on_page_locked(filepage); 1382 page_cache_release(filepage); 1383 filepage = NULL; 1384 goto repeat; 1385 } 1386 spin_unlock(&info->lock); 1387 } else { 1388 shmem_swp_unmap(entry); 1389 sbinfo = SHMEM_SB(inode->i_sb); 1390 if (sbinfo->max_blocks) { 1391 spin_lock(&sbinfo->stat_lock); 1392 if (sbinfo->free_blocks == 0 || 1393 shmem_acct_block(info->flags)) { 1394 spin_unlock(&sbinfo->stat_lock); 1395 spin_unlock(&info->lock); 1396 error = -ENOSPC; 1397 goto failed; 1398 } 1399 sbinfo->free_blocks--; 1400 inode->i_blocks += BLOCKS_PER_PAGE; 1401 spin_unlock(&sbinfo->stat_lock); 1402 } else if (shmem_acct_block(info->flags)) { 1403 spin_unlock(&info->lock); 1404 error = -ENOSPC; 1405 goto failed; 1406 } 1407 1408 if (!filepage) { 1409 int ret; 1410 1411 spin_unlock(&info->lock); 1412 filepage = shmem_alloc_page(gfp, info, idx); 1413 if (!filepage) { 1414 shmem_unacct_blocks(info->flags, 1); 1415 shmem_free_blocks(inode, 1); 1416 error = -ENOMEM; 1417 goto failed; 1418 } 1419 SetPageSwapBacked(filepage); 1420 1421 /* Precharge page while we can wait, compensate after */ 1422 error = mem_cgroup_cache_charge(filepage, current->mm, 1423 GFP_KERNEL); 1424 if (error) { 1425 page_cache_release(filepage); 1426 shmem_unacct_blocks(info->flags, 1); 1427 shmem_free_blocks(inode, 1); 1428 filepage = NULL; 1429 goto failed; 1430 } 1431 1432 spin_lock(&info->lock); 1433 entry = shmem_swp_alloc(info, idx, sgp); 1434 if (IS_ERR(entry)) 1435 error = PTR_ERR(entry); 1436 else { 1437 swap = *entry; 1438 shmem_swp_unmap(entry); 1439 } 1440 ret = error || swap.val; 1441 if (ret) 1442 mem_cgroup_uncharge_cache_page(filepage); 1443 else 1444 ret = add_to_page_cache_lru(filepage, mapping, 1445 idx, GFP_NOWAIT); 1446 /* 1447 * At add_to_page_cache_lru() failure, uncharge will 1448 * be done automatically. 1449 */ 1450 if (ret) { 1451 spin_unlock(&info->lock); 1452 page_cache_release(filepage); 1453 shmem_unacct_blocks(info->flags, 1); 1454 shmem_free_blocks(inode, 1); 1455 filepage = NULL; 1456 if (error) 1457 goto failed; 1458 goto repeat; 1459 } 1460 info->flags |= SHMEM_PAGEIN; 1461 } 1462 1463 info->alloced++; 1464 spin_unlock(&info->lock); 1465 clear_highpage(filepage); 1466 flush_dcache_page(filepage); 1467 SetPageUptodate(filepage); 1468 if (sgp == SGP_DIRTY) 1469 set_page_dirty(filepage); 1470 } 1471done: 1472 *pagep = filepage; 1473 return 0; 1474 1475failed: 1476 if (*pagep != filepage) { 1477 unlock_page(filepage); 1478 page_cache_release(filepage); 1479 } 1480 return error; 1481} 1482 1483static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1484{ 1485 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1486 int error; 1487 int ret; 1488 1489 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1490 return VM_FAULT_SIGBUS; 1491 1492 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1493 if (error) 1494 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1495 1496 return ret | VM_FAULT_LOCKED; 1497} 1498 1499#ifdef CONFIG_NUMA 1500static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1501{ 1502 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1503 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1504} 1505 1506static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1507 unsigned long addr) 1508{ 1509 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1510 unsigned long idx; 1511 1512 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1513 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1514} 1515#endif 1516 1517int shmem_lock(struct file *file, int lock, struct user_struct *user) 1518{ 1519 struct inode *inode = file->f_path.dentry->d_inode; 1520 struct shmem_inode_info *info = SHMEM_I(inode); 1521 int retval = -ENOMEM; 1522 1523 spin_lock(&info->lock); 1524 if (lock && !(info->flags & VM_LOCKED)) { 1525 if (!user_shm_lock(inode->i_size, user)) 1526 goto out_nomem; 1527 info->flags |= VM_LOCKED; 1528 mapping_set_unevictable(file->f_mapping); 1529 } 1530 if (!lock && (info->flags & VM_LOCKED) && user) { 1531 user_shm_unlock(inode->i_size, user); 1532 info->flags &= ~VM_LOCKED; 1533 mapping_clear_unevictable(file->f_mapping); 1534 scan_mapping_unevictable_pages(file->f_mapping); 1535 } 1536 retval = 0; 1537 1538out_nomem: 1539 spin_unlock(&info->lock); 1540 return retval; 1541} 1542 1543static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1544{ 1545 file_accessed(file); 1546 vma->vm_ops = &shmem_vm_ops; 1547 vma->vm_flags |= VM_CAN_NONLINEAR; 1548 return 0; 1549} 1550 1551static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, 1552 int mode, dev_t dev, unsigned long flags) 1553{ 1554 struct inode *inode; 1555 struct shmem_inode_info *info; 1556 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1557 1558 if (shmem_reserve_inode(sb)) 1559 return NULL; 1560 1561 inode = new_inode(sb); 1562 if (inode) { 1563 inode_init_owner(inode, dir, mode); 1564 inode->i_blocks = 0; 1565 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1566 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1567 inode->i_generation = get_seconds(); 1568 info = SHMEM_I(inode); 1569 memset(info, 0, (char *)inode - (char *)info); 1570 spin_lock_init(&info->lock); 1571 info->flags = flags & VM_NORESERVE; 1572 INIT_LIST_HEAD(&info->swaplist); 1573 cache_no_acl(inode); 1574 1575 switch (mode & S_IFMT) { 1576 default: 1577 inode->i_op = &shmem_special_inode_operations; 1578 init_special_inode(inode, mode, dev); 1579 break; 1580 case S_IFREG: 1581 inode->i_mapping->a_ops = &shmem_aops; 1582 inode->i_op = &shmem_inode_operations; 1583 inode->i_fop = &shmem_file_operations; 1584 mpol_shared_policy_init(&info->policy, 1585 shmem_get_sbmpol(sbinfo)); 1586 break; 1587 case S_IFDIR: 1588 inc_nlink(inode); 1589 /* Some things misbehave if size == 0 on a directory */ 1590 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1591 inode->i_op = &shmem_dir_inode_operations; 1592 inode->i_fop = &simple_dir_operations; 1593 break; 1594 case S_IFLNK: 1595 /* 1596 * Must not load anything in the rbtree, 1597 * mpol_free_shared_policy will not be called. 1598 */ 1599 mpol_shared_policy_init(&info->policy, NULL); 1600 break; 1601 } 1602 } else 1603 shmem_free_inode(sb); 1604 return inode; 1605} 1606 1607#ifdef CONFIG_TMPFS 1608static const struct inode_operations shmem_symlink_inode_operations; 1609static const struct inode_operations shmem_symlink_inline_operations; 1610 1611/* 1612 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1613 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1614 * below the loop driver, in the generic fashion that many filesystems support. 1615 */ 1616static int shmem_readpage(struct file *file, struct page *page) 1617{ 1618 struct inode *inode = page->mapping->host; 1619 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1620 unlock_page(page); 1621 return error; 1622} 1623 1624static int 1625shmem_write_begin(struct file *file, struct address_space *mapping, 1626 loff_t pos, unsigned len, unsigned flags, 1627 struct page **pagep, void **fsdata) 1628{ 1629 struct inode *inode = mapping->host; 1630 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1631 *pagep = NULL; 1632 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1633} 1634 1635static int 1636shmem_write_end(struct file *file, struct address_space *mapping, 1637 loff_t pos, unsigned len, unsigned copied, 1638 struct page *page, void *fsdata) 1639{ 1640 struct inode *inode = mapping->host; 1641 1642 if (pos + copied > inode->i_size) 1643 i_size_write(inode, pos + copied); 1644 1645 set_page_dirty(page); 1646 unlock_page(page); 1647 page_cache_release(page); 1648 1649 return copied; 1650} 1651 1652static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1653{ 1654 struct inode *inode = filp->f_path.dentry->d_inode; 1655 struct address_space *mapping = inode->i_mapping; 1656 unsigned long index, offset; 1657 enum sgp_type sgp = SGP_READ; 1658 1659 /* 1660 * Might this read be for a stacking filesystem? Then when reading 1661 * holes of a sparse file, we actually need to allocate those pages, 1662 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1663 */ 1664 if (segment_eq(get_fs(), KERNEL_DS)) 1665 sgp = SGP_DIRTY; 1666 1667 index = *ppos >> PAGE_CACHE_SHIFT; 1668 offset = *ppos & ~PAGE_CACHE_MASK; 1669 1670 for (;;) { 1671 struct page *page = NULL; 1672 unsigned long end_index, nr, ret; 1673 loff_t i_size = i_size_read(inode); 1674 1675 end_index = i_size >> PAGE_CACHE_SHIFT; 1676 if (index > end_index) 1677 break; 1678 if (index == end_index) { 1679 nr = i_size & ~PAGE_CACHE_MASK; 1680 if (nr <= offset) 1681 break; 1682 } 1683 1684 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1685 if (desc->error) { 1686 if (desc->error == -EINVAL) 1687 desc->error = 0; 1688 break; 1689 } 1690 if (page) 1691 unlock_page(page); 1692 1693 /* 1694 * We must evaluate after, since reads (unlike writes) 1695 * are called without i_mutex protection against truncate 1696 */ 1697 nr = PAGE_CACHE_SIZE; 1698 i_size = i_size_read(inode); 1699 end_index = i_size >> PAGE_CACHE_SHIFT; 1700 if (index == end_index) { 1701 nr = i_size & ~PAGE_CACHE_MASK; 1702 if (nr <= offset) { 1703 if (page) 1704 page_cache_release(page); 1705 break; 1706 } 1707 } 1708 nr -= offset; 1709 1710 if (page) { 1711 /* 1712 * If users can be writing to this page using arbitrary 1713 * virtual addresses, take care about potential aliasing 1714 * before reading the page on the kernel side. 1715 */ 1716 if (mapping_writably_mapped(mapping)) 1717 flush_dcache_page(page); 1718 /* 1719 * Mark the page accessed if we read the beginning. 1720 */ 1721 if (!offset) 1722 mark_page_accessed(page); 1723 } else { 1724 page = ZERO_PAGE(0); 1725 page_cache_get(page); 1726 } 1727 1728 /* 1729 * Ok, we have the page, and it's up-to-date, so 1730 * now we can copy it to user space... 1731 * 1732 * The actor routine returns how many bytes were actually used.. 1733 * NOTE! This may not be the same as how much of a user buffer 1734 * we filled up (we may be padding etc), so we can only update 1735 * "pos" here (the actor routine has to update the user buffer 1736 * pointers and the remaining count). 1737 */ 1738 ret = actor(desc, page, offset, nr); 1739 offset += ret; 1740 index += offset >> PAGE_CACHE_SHIFT; 1741 offset &= ~PAGE_CACHE_MASK; 1742 1743 page_cache_release(page); 1744 if (ret != nr || !desc->count) 1745 break; 1746 1747 cond_resched(); 1748 } 1749 1750 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1751 file_accessed(filp); 1752} 1753 1754static ssize_t shmem_file_aio_read(struct kiocb *iocb, 1755 const struct iovec *iov, unsigned long nr_segs, loff_t pos) 1756{ 1757 struct file *filp = iocb->ki_filp; 1758 ssize_t retval; 1759 unsigned long seg; 1760 size_t count; 1761 loff_t *ppos = &iocb->ki_pos; 1762 1763 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); 1764 if (retval) 1765 return retval; 1766 1767 for (seg = 0; seg < nr_segs; seg++) { 1768 read_descriptor_t desc; 1769 1770 desc.written = 0; 1771 desc.arg.buf = iov[seg].iov_base; 1772 desc.count = iov[seg].iov_len; 1773 if (desc.count == 0) 1774 continue; 1775 desc.error = 0; 1776 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1777 retval += desc.written; 1778 if (desc.error) { 1779 retval = retval ?: desc.error; 1780 break; 1781 } 1782 if (desc.count > 0) 1783 break; 1784 } 1785 return retval; 1786} 1787 1788static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1789{ 1790 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1791 1792 buf->f_type = TMPFS_MAGIC; 1793 buf->f_bsize = PAGE_CACHE_SIZE; 1794 buf->f_namelen = NAME_MAX; 1795 spin_lock(&sbinfo->stat_lock); 1796 if (sbinfo->max_blocks) { 1797 buf->f_blocks = sbinfo->max_blocks; 1798 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1799 } 1800 if (sbinfo->max_inodes) { 1801 buf->f_files = sbinfo->max_inodes; 1802 buf->f_ffree = sbinfo->free_inodes; 1803 } 1804 /* else leave those fields 0 like simple_statfs */ 1805 spin_unlock(&sbinfo->stat_lock); 1806 return 0; 1807} 1808 1809/* 1810 * File creation. Allocate an inode, and we're done.. 1811 */ 1812static int 1813shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1814{ 1815 struct inode *inode; 1816 int error = -ENOSPC; 1817 1818 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); 1819 if (inode) { 1820 error = security_inode_init_security(inode, dir, NULL, NULL, 1821 NULL); 1822 if (error) { 1823 if (error != -EOPNOTSUPP) { 1824 iput(inode); 1825 return error; 1826 } 1827 } 1828#ifdef CONFIG_TMPFS_POSIX_ACL 1829 error = generic_acl_init(inode, dir); 1830 if (error) { 1831 iput(inode); 1832 return error; 1833 } 1834#else 1835 error = 0; 1836#endif 1837 dir->i_size += BOGO_DIRENT_SIZE; 1838 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1839 d_instantiate(dentry, inode); 1840 dget(dentry); /* Extra count - pin the dentry in core */ 1841 } 1842 return error; 1843} 1844 1845static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1846{ 1847 int error; 1848 1849 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1850 return error; 1851 inc_nlink(dir); 1852 return 0; 1853} 1854 1855static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1856 struct nameidata *nd) 1857{ 1858 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1859} 1860 1861/* 1862 * Link a file.. 1863 */ 1864static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1865{ 1866 struct inode *inode = old_dentry->d_inode; 1867 int ret; 1868 1869 /* 1870 * No ordinary (disk based) filesystem counts links as inodes; 1871 * but each new link needs a new dentry, pinning lowmem, and 1872 * tmpfs dentries cannot be pruned until they are unlinked. 1873 */ 1874 ret = shmem_reserve_inode(inode->i_sb); 1875 if (ret) 1876 goto out; 1877 1878 dir->i_size += BOGO_DIRENT_SIZE; 1879 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1880 inc_nlink(inode); 1881 atomic_inc(&inode->i_count); /* New dentry reference */ 1882 dget(dentry); /* Extra pinning count for the created dentry */ 1883 d_instantiate(dentry, inode); 1884out: 1885 return ret; 1886} 1887 1888static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1889{ 1890 struct inode *inode = dentry->d_inode; 1891 1892 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1893 shmem_free_inode(inode->i_sb); 1894 1895 dir->i_size -= BOGO_DIRENT_SIZE; 1896 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1897 drop_nlink(inode); 1898 dput(dentry); /* Undo the count from "create" - this does all the work */ 1899 return 0; 1900} 1901 1902static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1903{ 1904 if (!simple_empty(dentry)) 1905 return -ENOTEMPTY; 1906 1907 drop_nlink(dentry->d_inode); 1908 drop_nlink(dir); 1909 return shmem_unlink(dir, dentry); 1910} 1911 1912/* 1913 * The VFS layer already does all the dentry stuff for rename, 1914 * we just have to decrement the usage count for the target if 1915 * it exists so that the VFS layer correctly free's it when it 1916 * gets overwritten. 1917 */ 1918static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1919{ 1920 struct inode *inode = old_dentry->d_inode; 1921 int they_are_dirs = S_ISDIR(inode->i_mode); 1922 1923 if (!simple_empty(new_dentry)) 1924 return -ENOTEMPTY; 1925 1926 if (new_dentry->d_inode) { 1927 (void) shmem_unlink(new_dir, new_dentry); 1928 if (they_are_dirs) 1929 drop_nlink(old_dir); 1930 } else if (they_are_dirs) { 1931 drop_nlink(old_dir); 1932 inc_nlink(new_dir); 1933 } 1934 1935 old_dir->i_size -= BOGO_DIRENT_SIZE; 1936 new_dir->i_size += BOGO_DIRENT_SIZE; 1937 old_dir->i_ctime = old_dir->i_mtime = 1938 new_dir->i_ctime = new_dir->i_mtime = 1939 inode->i_ctime = CURRENT_TIME; 1940 return 0; 1941} 1942 1943static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1944{ 1945 int error; 1946 int len; 1947 struct inode *inode; 1948 struct page *page = NULL; 1949 char *kaddr; 1950 struct shmem_inode_info *info; 1951 1952 len = strlen(symname) + 1; 1953 if (len > PAGE_CACHE_SIZE) 1954 return -ENAMETOOLONG; 1955 1956 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); 1957 if (!inode) 1958 return -ENOSPC; 1959 1960 error = security_inode_init_security(inode, dir, NULL, NULL, 1961 NULL); 1962 if (error) { 1963 if (error != -EOPNOTSUPP) { 1964 iput(inode); 1965 return error; 1966 } 1967 error = 0; 1968 } 1969 1970 info = SHMEM_I(inode); 1971 inode->i_size = len-1; 1972 if (len <= (char *)inode - (char *)info) { 1973 /* do it inline */ 1974 memcpy(info, symname, len); 1975 inode->i_op = &shmem_symlink_inline_operations; 1976 } else { 1977 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1978 if (error) { 1979 iput(inode); 1980 return error; 1981 } 1982 inode->i_mapping->a_ops = &shmem_aops; 1983 inode->i_op = &shmem_symlink_inode_operations; 1984 kaddr = kmap_atomic(page, KM_USER0); 1985 memcpy(kaddr, symname, len); 1986 kunmap_atomic(kaddr, KM_USER0); 1987 set_page_dirty(page); 1988 unlock_page(page); 1989 page_cache_release(page); 1990 } 1991 dir->i_size += BOGO_DIRENT_SIZE; 1992 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1993 d_instantiate(dentry, inode); 1994 dget(dentry); 1995 return 0; 1996} 1997 1998static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1999{ 2000 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 2001 return NULL; 2002} 2003 2004static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 2005{ 2006 struct page *page = NULL; 2007 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 2008 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 2009 if (page) 2010 unlock_page(page); 2011 return page; 2012} 2013 2014static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 2015{ 2016 if (!IS_ERR(nd_get_link(nd))) { 2017 struct page *page = cookie; 2018 kunmap(page); 2019 mark_page_accessed(page); 2020 page_cache_release(page); 2021 } 2022} 2023 2024static const struct inode_operations shmem_symlink_inline_operations = { 2025 .readlink = generic_readlink, 2026 .follow_link = shmem_follow_link_inline, 2027}; 2028 2029static const struct inode_operations shmem_symlink_inode_operations = { 2030 .readlink = generic_readlink, 2031 .follow_link = shmem_follow_link, 2032 .put_link = shmem_put_link, 2033}; 2034 2035#ifdef CONFIG_TMPFS_POSIX_ACL 2036/* 2037 * Superblocks without xattr inode operations will get security.* xattr 2038 * support from the VFS "for free". As soon as we have any other xattrs 2039 * like ACLs, we also need to implement the security.* handlers at 2040 * filesystem level, though. 2041 */ 2042 2043static size_t shmem_xattr_security_list(struct dentry *dentry, char *list, 2044 size_t list_len, const char *name, 2045 size_t name_len, int handler_flags) 2046{ 2047 return security_inode_listsecurity(dentry->d_inode, list, list_len); 2048} 2049 2050static int shmem_xattr_security_get(struct dentry *dentry, const char *name, 2051 void *buffer, size_t size, int handler_flags) 2052{ 2053 if (strcmp(name, "") == 0) 2054 return -EINVAL; 2055 return xattr_getsecurity(dentry->d_inode, name, buffer, size); 2056} 2057 2058static int shmem_xattr_security_set(struct dentry *dentry, const char *name, 2059 const void *value, size_t size, int flags, int handler_flags) 2060{ 2061 if (strcmp(name, "") == 0) 2062 return -EINVAL; 2063 return security_inode_setsecurity(dentry->d_inode, name, value, 2064 size, flags); 2065} 2066 2067static const struct xattr_handler shmem_xattr_security_handler = { 2068 .prefix = XATTR_SECURITY_PREFIX, 2069 .list = shmem_xattr_security_list, 2070 .get = shmem_xattr_security_get, 2071 .set = shmem_xattr_security_set, 2072}; 2073 2074static const struct xattr_handler *shmem_xattr_handlers[] = { 2075 &generic_acl_access_handler, 2076 &generic_acl_default_handler, 2077 &shmem_xattr_security_handler, 2078 NULL 2079}; 2080#endif 2081 2082static struct dentry *shmem_get_parent(struct dentry *child) 2083{ 2084 return ERR_PTR(-ESTALE); 2085} 2086 2087static int shmem_match(struct inode *ino, void *vfh) 2088{ 2089 __u32 *fh = vfh; 2090 __u64 inum = fh[2]; 2091 inum = (inum << 32) | fh[1]; 2092 return ino->i_ino == inum && fh[0] == ino->i_generation; 2093} 2094 2095static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2096 struct fid *fid, int fh_len, int fh_type) 2097{ 2098 struct inode *inode; 2099 struct dentry *dentry = NULL; 2100 u64 inum = fid->raw[2]; 2101 inum = (inum << 32) | fid->raw[1]; 2102 2103 if (fh_len < 3) 2104 return NULL; 2105 2106 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2107 shmem_match, fid->raw); 2108 if (inode) { 2109 dentry = d_find_alias(inode); 2110 iput(inode); 2111 } 2112 2113 return dentry; 2114} 2115 2116static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2117 int connectable) 2118{ 2119 struct inode *inode = dentry->d_inode; 2120 2121 if (*len < 3) 2122 return 255; 2123 2124 if (hlist_unhashed(&inode->i_hash)) { 2125 /* Unfortunately insert_inode_hash is not idempotent, 2126 * so as we hash inodes here rather than at creation 2127 * time, we need a lock to ensure we only try 2128 * to do it once 2129 */ 2130 static DEFINE_SPINLOCK(lock); 2131 spin_lock(&lock); 2132 if (hlist_unhashed(&inode->i_hash)) 2133 __insert_inode_hash(inode, 2134 inode->i_ino + inode->i_generation); 2135 spin_unlock(&lock); 2136 } 2137 2138 fh[0] = inode->i_generation; 2139 fh[1] = inode->i_ino; 2140 fh[2] = ((__u64)inode->i_ino) >> 32; 2141 2142 *len = 3; 2143 return 1; 2144} 2145 2146static const struct export_operations shmem_export_ops = { 2147 .get_parent = shmem_get_parent, 2148 .encode_fh = shmem_encode_fh, 2149 .fh_to_dentry = shmem_fh_to_dentry, 2150}; 2151 2152static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 2153 bool remount) 2154{ 2155 char *this_char, *value, *rest; 2156 2157 while (options != NULL) { 2158 this_char = options; 2159 for (;;) { 2160 /* 2161 * NUL-terminate this option: unfortunately, 2162 * mount options form a comma-separated list, 2163 * but mpol's nodelist may also contain commas. 2164 */ 2165 options = strchr(options, ','); 2166 if (options == NULL) 2167 break; 2168 options++; 2169 if (!isdigit(*options)) { 2170 options[-1] = '\0'; 2171 break; 2172 } 2173 } 2174 if (!*this_char) 2175 continue; 2176 if ((value = strchr(this_char,'=')) != NULL) { 2177 *value++ = 0; 2178 } else { 2179 printk(KERN_ERR 2180 "tmpfs: No value for mount option '%s'\n", 2181 this_char); 2182 return 1; 2183 } 2184 2185 if (!strcmp(this_char,"size")) { 2186 unsigned long long size; 2187 size = memparse(value,&rest); 2188 if (*rest == '%') { 2189 size <<= PAGE_SHIFT; 2190 size *= totalram_pages; 2191 do_div(size, 100); 2192 rest++; 2193 } 2194 if (*rest) 2195 goto bad_val; 2196 sbinfo->max_blocks = 2197 DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2198 } else if (!strcmp(this_char,"nr_blocks")) { 2199 sbinfo->max_blocks = memparse(value, &rest); 2200 if (*rest) 2201 goto bad_val; 2202 } else if (!strcmp(this_char,"nr_inodes")) { 2203 sbinfo->max_inodes = memparse(value, &rest); 2204 if (*rest) 2205 goto bad_val; 2206 } else if (!strcmp(this_char,"mode")) { 2207 if (remount) 2208 continue; 2209 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; 2210 if (*rest) 2211 goto bad_val; 2212 } else if (!strcmp(this_char,"uid")) { 2213 if (remount) 2214 continue; 2215 sbinfo->uid = simple_strtoul(value, &rest, 0); 2216 if (*rest) 2217 goto bad_val; 2218 } else if (!strcmp(this_char,"gid")) { 2219 if (remount) 2220 continue; 2221 sbinfo->gid = simple_strtoul(value, &rest, 0); 2222 if (*rest) 2223 goto bad_val; 2224 } else if (!strcmp(this_char,"mpol")) { 2225 if (mpol_parse_str(value, &sbinfo->mpol, 1)) 2226 goto bad_val; 2227 } else { 2228 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2229 this_char); 2230 return 1; 2231 } 2232 } 2233 return 0; 2234 2235bad_val: 2236 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2237 value, this_char); 2238 return 1; 2239 2240} 2241 2242static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2243{ 2244 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2245 struct shmem_sb_info config = *sbinfo; 2246 unsigned long blocks; 2247 unsigned long inodes; 2248 int error = -EINVAL; 2249 2250 if (shmem_parse_options(data, &config, true)) 2251 return error; 2252 2253 spin_lock(&sbinfo->stat_lock); 2254 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2255 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2256 if (config.max_blocks < blocks) 2257 goto out; 2258 if (config.max_inodes < inodes) 2259 goto out; 2260 /* 2261 * Those tests also disallow limited->unlimited while any are in 2262 * use, so i_blocks will always be zero when max_blocks is zero; 2263 * but we must separately disallow unlimited->limited, because 2264 * in that case we have no record of how much is already in use. 2265 */ 2266 if (config.max_blocks && !sbinfo->max_blocks) 2267 goto out; 2268 if (config.max_inodes && !sbinfo->max_inodes) 2269 goto out; 2270 2271 error = 0; 2272 sbinfo->max_blocks = config.max_blocks; 2273 sbinfo->free_blocks = config.max_blocks - blocks; 2274 sbinfo->max_inodes = config.max_inodes; 2275 sbinfo->free_inodes = config.max_inodes - inodes; 2276 2277 mpol_put(sbinfo->mpol); 2278 sbinfo->mpol = config.mpol; /* transfers initial ref */ 2279out: 2280 spin_unlock(&sbinfo->stat_lock); 2281 return error; 2282} 2283 2284static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) 2285{ 2286 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); 2287 2288 if (sbinfo->max_blocks != shmem_default_max_blocks()) 2289 seq_printf(seq, ",size=%luk", 2290 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); 2291 if (sbinfo->max_inodes != shmem_default_max_inodes()) 2292 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); 2293 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) 2294 seq_printf(seq, ",mode=%03o", sbinfo->mode); 2295 if (sbinfo->uid != 0) 2296 seq_printf(seq, ",uid=%u", sbinfo->uid); 2297 if (sbinfo->gid != 0) 2298 seq_printf(seq, ",gid=%u", sbinfo->gid); 2299 shmem_show_mpol(seq, sbinfo->mpol); 2300 return 0; 2301} 2302#endif /* CONFIG_TMPFS */ 2303 2304static void shmem_put_super(struct super_block *sb) 2305{ 2306 kfree(sb->s_fs_info); 2307 sb->s_fs_info = NULL; 2308} 2309 2310int shmem_fill_super(struct super_block *sb, void *data, int silent) 2311{ 2312 struct inode *inode; 2313 struct dentry *root; 2314 struct shmem_sb_info *sbinfo; 2315 int err = -ENOMEM; 2316 2317 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2318 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), 2319 L1_CACHE_BYTES), GFP_KERNEL); 2320 if (!sbinfo) 2321 return -ENOMEM; 2322 2323 sbinfo->mode = S_IRWXUGO | S_ISVTX; 2324 sbinfo->uid = current_fsuid(); 2325 sbinfo->gid = current_fsgid(); 2326 sb->s_fs_info = sbinfo; 2327 2328#ifdef CONFIG_TMPFS 2329 /* 2330 * Per default we only allow half of the physical ram per 2331 * tmpfs instance, limiting inodes to one per page of lowmem; 2332 * but the internal instance is left unlimited. 2333 */ 2334 if (!(sb->s_flags & MS_NOUSER)) { 2335 sbinfo->max_blocks = shmem_default_max_blocks(); 2336 sbinfo->max_inodes = shmem_default_max_inodes(); 2337 if (shmem_parse_options(data, sbinfo, false)) { 2338 err = -EINVAL; 2339 goto failed; 2340 } 2341 } 2342 sb->s_export_op = &shmem_export_ops; 2343#else 2344 sb->s_flags |= MS_NOUSER; 2345#endif 2346 2347 spin_lock_init(&sbinfo->stat_lock); 2348 sbinfo->free_blocks = sbinfo->max_blocks; 2349 sbinfo->free_inodes = sbinfo->max_inodes; 2350 2351 sb->s_maxbytes = SHMEM_MAX_BYTES; 2352 sb->s_blocksize = PAGE_CACHE_SIZE; 2353 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2354 sb->s_magic = TMPFS_MAGIC; 2355 sb->s_op = &shmem_ops; 2356 sb->s_time_gran = 1; 2357#ifdef CONFIG_TMPFS_POSIX_ACL 2358 sb->s_xattr = shmem_xattr_handlers; 2359 sb->s_flags |= MS_POSIXACL; 2360#endif 2361 2362 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); 2363 if (!inode) 2364 goto failed; 2365 inode->i_uid = sbinfo->uid; 2366 inode->i_gid = sbinfo->gid; 2367 root = d_alloc_root(inode); 2368 if (!root) 2369 goto failed_iput; 2370 sb->s_root = root; 2371 return 0; 2372 2373failed_iput: 2374 iput(inode); 2375failed: 2376 shmem_put_super(sb); 2377 return err; 2378} 2379 2380static struct kmem_cache *shmem_inode_cachep; 2381 2382static struct inode *shmem_alloc_inode(struct super_block *sb) 2383{ 2384 struct shmem_inode_info *p; 2385 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2386 if (!p) 2387 return NULL; 2388 return &p->vfs_inode; 2389} 2390 2391static void shmem_destroy_inode(struct inode *inode) 2392{ 2393 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2394 /* only struct inode is valid if it's an inline symlink */ 2395 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2396 } 2397 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2398} 2399 2400static void init_once(void *foo) 2401{ 2402 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2403 2404 inode_init_once(&p->vfs_inode); 2405} 2406 2407static int init_inodecache(void) 2408{ 2409 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2410 sizeof(struct shmem_inode_info), 2411 0, SLAB_PANIC, init_once); 2412 return 0; 2413} 2414 2415static void destroy_inodecache(void) 2416{ 2417 kmem_cache_destroy(shmem_inode_cachep); 2418} 2419 2420static const struct address_space_operations shmem_aops = { 2421 .writepage = shmem_writepage, 2422 .set_page_dirty = __set_page_dirty_no_writeback, 2423#ifdef CONFIG_TMPFS 2424 .readpage = shmem_readpage, 2425 .write_begin = shmem_write_begin, 2426 .write_end = shmem_write_end, 2427#endif 2428 .migratepage = migrate_page, 2429 .error_remove_page = generic_error_remove_page, 2430}; 2431 2432static const struct file_operations shmem_file_operations = { 2433 .mmap = shmem_mmap, 2434#ifdef CONFIG_TMPFS 2435 .llseek = generic_file_llseek, 2436 .read = do_sync_read, 2437 .write = do_sync_write, 2438 .aio_read = shmem_file_aio_read, 2439 .aio_write = generic_file_aio_write, 2440 .fsync = noop_fsync, 2441 .splice_read = generic_file_splice_read, 2442 .splice_write = generic_file_splice_write, 2443#endif 2444}; 2445 2446static const struct inode_operations shmem_inode_operations = { 2447 .setattr = shmem_notify_change, 2448 .truncate_range = shmem_truncate_range, 2449#ifdef CONFIG_TMPFS_POSIX_ACL 2450 .setxattr = generic_setxattr, 2451 .getxattr = generic_getxattr, 2452 .listxattr = generic_listxattr, 2453 .removexattr = generic_removexattr, 2454 .check_acl = generic_check_acl, 2455#endif 2456 2457}; 2458 2459static const struct inode_operations shmem_dir_inode_operations = { 2460#ifdef CONFIG_TMPFS 2461 .create = shmem_create, 2462 .lookup = simple_lookup, 2463 .link = shmem_link, 2464 .unlink = shmem_unlink, 2465 .symlink = shmem_symlink, 2466 .mkdir = shmem_mkdir, 2467 .rmdir = shmem_rmdir, 2468 .mknod = shmem_mknod, 2469 .rename = shmem_rename, 2470#endif 2471#ifdef CONFIG_TMPFS_POSIX_ACL 2472 .setattr = shmem_notify_change, 2473 .setxattr = generic_setxattr, 2474 .getxattr = generic_getxattr, 2475 .listxattr = generic_listxattr, 2476 .removexattr = generic_removexattr, 2477 .check_acl = generic_check_acl, 2478#endif 2479}; 2480 2481static const struct inode_operations shmem_special_inode_operations = { 2482#ifdef CONFIG_TMPFS_POSIX_ACL 2483 .setattr = shmem_notify_change, 2484 .setxattr = generic_setxattr, 2485 .getxattr = generic_getxattr, 2486 .listxattr = generic_listxattr, 2487 .removexattr = generic_removexattr, 2488 .check_acl = generic_check_acl, 2489#endif 2490}; 2491 2492static const struct super_operations shmem_ops = { 2493 .alloc_inode = shmem_alloc_inode, 2494 .destroy_inode = shmem_destroy_inode, 2495#ifdef CONFIG_TMPFS 2496 .statfs = shmem_statfs, 2497 .remount_fs = shmem_remount_fs, 2498 .show_options = shmem_show_options, 2499#endif 2500 .evict_inode = shmem_evict_inode, 2501 .drop_inode = generic_delete_inode, 2502 .put_super = shmem_put_super, 2503}; 2504 2505static const struct vm_operations_struct shmem_vm_ops = { 2506 .fault = shmem_fault, 2507#ifdef CONFIG_NUMA 2508 .set_policy = shmem_set_policy, 2509 .get_policy = shmem_get_policy, 2510#endif 2511}; 2512 2513 2514static int shmem_get_sb(struct file_system_type *fs_type, 2515 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2516{ 2517 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2518} 2519 2520static struct file_system_type tmpfs_fs_type = { 2521 .owner = THIS_MODULE, 2522 .name = "tmpfs", 2523 .get_sb = shmem_get_sb, 2524 .kill_sb = kill_litter_super, 2525}; 2526 2527int __init init_tmpfs(void) 2528{ 2529 int error; 2530 2531 error = bdi_init(&shmem_backing_dev_info); 2532 if (error) 2533 goto out4; 2534 2535 error = init_inodecache(); 2536 if (error) 2537 goto out3; 2538 2539 error = register_filesystem(&tmpfs_fs_type); 2540 if (error) { 2541 printk(KERN_ERR "Could not register tmpfs\n"); 2542 goto out2; 2543 } 2544 2545 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2546 tmpfs_fs_type.name, NULL); 2547 if (IS_ERR(shm_mnt)) { 2548 error = PTR_ERR(shm_mnt); 2549 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2550 goto out1; 2551 } 2552 return 0; 2553 2554out1: 2555 unregister_filesystem(&tmpfs_fs_type); 2556out2: 2557 destroy_inodecache(); 2558out3: 2559 bdi_destroy(&shmem_backing_dev_info); 2560out4: 2561 shm_mnt = ERR_PTR(error); 2562 return error; 2563} 2564 2565#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2566/** 2567 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2568 * @inode: the inode to be searched 2569 * @pgoff: the offset to be searched 2570 * @pagep: the pointer for the found page to be stored 2571 * @ent: the pointer for the found swap entry to be stored 2572 * 2573 * If a page is found, refcount of it is incremented. Callers should handle 2574 * these refcount. 2575 */ 2576void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2577 struct page **pagep, swp_entry_t *ent) 2578{ 2579 swp_entry_t entry = { .val = 0 }, *ptr; 2580 struct page *page = NULL; 2581 struct shmem_inode_info *info = SHMEM_I(inode); 2582 2583 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2584 goto out; 2585 2586 spin_lock(&info->lock); 2587 ptr = shmem_swp_entry(info, pgoff, NULL); 2588#ifdef CONFIG_SWAP 2589 if (ptr && ptr->val) { 2590 entry.val = ptr->val; 2591 page = find_get_page(&swapper_space, entry.val); 2592 } else 2593#endif 2594 page = find_get_page(inode->i_mapping, pgoff); 2595 if (ptr) 2596 shmem_swp_unmap(ptr); 2597 spin_unlock(&info->lock); 2598out: 2599 *pagep = page; 2600 *ent = entry; 2601} 2602#endif 2603 2604#else /* !CONFIG_SHMEM */ 2605 2606/* 2607 * tiny-shmem: simple shmemfs and tmpfs using ramfs code 2608 * 2609 * This is intended for small system where the benefits of the full 2610 * shmem code (swap-backed and resource-limited) are outweighed by 2611 * their complexity. On systems without swap this code should be 2612 * effectively equivalent, but much lighter weight. 2613 */ 2614 2615#include <linux/ramfs.h> 2616 2617static struct file_system_type tmpfs_fs_type = { 2618 .name = "tmpfs", 2619 .get_sb = ramfs_get_sb, 2620 .kill_sb = kill_litter_super, 2621}; 2622 2623int __init init_tmpfs(void) 2624{ 2625 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); 2626 2627 shm_mnt = kern_mount(&tmpfs_fs_type); 2628 BUG_ON(IS_ERR(shm_mnt)); 2629 2630 return 0; 2631} 2632 2633int shmem_unuse(swp_entry_t entry, struct page *page) 2634{ 2635 return 0; 2636} 2637 2638int shmem_lock(struct file *file, int lock, struct user_struct *user) 2639{ 2640 return 0; 2641} 2642 2643#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2644/** 2645 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2646 * @inode: the inode to be searched 2647 * @pgoff: the offset to be searched 2648 * @pagep: the pointer for the found page to be stored 2649 * @ent: the pointer for the found swap entry to be stored 2650 * 2651 * If a page is found, refcount of it is incremented. Callers should handle 2652 * these refcount. 2653 */ 2654void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2655 struct page **pagep, swp_entry_t *ent) 2656{ 2657 struct page *page = NULL; 2658 2659 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2660 goto out; 2661 page = find_get_page(inode->i_mapping, pgoff); 2662out: 2663 *pagep = page; 2664 *ent = (swp_entry_t){ .val = 0 }; 2665} 2666#endif 2667 2668#define shmem_vm_ops generic_file_vm_ops 2669#define shmem_file_operations ramfs_file_operations 2670#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) 2671#define shmem_acct_size(flags, size) 0 2672#define shmem_unacct_size(flags, size) do {} while (0) 2673#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE 2674 2675#endif /* CONFIG_SHMEM */ 2676 2677/* common code */ 2678 2679/** 2680 * shmem_file_setup - get an unlinked file living in tmpfs 2681 * @name: name for dentry (to be seen in /proc/<pid>/maps 2682 * @size: size to be set for the file 2683 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size 2684 */ 2685struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) 2686{ 2687 int error; 2688 struct file *file; 2689 struct inode *inode; 2690 struct path path; 2691 struct dentry *root; 2692 struct qstr this; 2693 2694 if (IS_ERR(shm_mnt)) 2695 return (void *)shm_mnt; 2696 2697 if (size < 0 || size > SHMEM_MAX_BYTES) 2698 return ERR_PTR(-EINVAL); 2699 2700 if (shmem_acct_size(flags, size)) 2701 return ERR_PTR(-ENOMEM); 2702 2703 error = -ENOMEM; 2704 this.name = name; 2705 this.len = strlen(name); 2706 this.hash = 0; /* will go */ 2707 root = shm_mnt->mnt_root; 2708 path.dentry = d_alloc(root, &this); 2709 if (!path.dentry) 2710 goto put_memory; 2711 path.mnt = mntget(shm_mnt); 2712 2713 error = -ENOSPC; 2714 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); 2715 if (!inode) 2716 goto put_dentry; 2717 2718 d_instantiate(path.dentry, inode); 2719 inode->i_size = size; 2720 inode->i_nlink = 0; /* It is unlinked */ 2721#ifndef CONFIG_MMU 2722 error = ramfs_nommu_expand_for_mapping(inode, size); 2723 if (error) 2724 goto put_dentry; 2725#endif 2726 2727 error = -ENFILE; 2728 file = alloc_file(&path, FMODE_WRITE | FMODE_READ, 2729 &shmem_file_operations); 2730 if (!file) 2731 goto put_dentry; 2732 2733 return file; 2734 2735put_dentry: 2736 path_put(&path); 2737put_memory: 2738 shmem_unacct_size(flags, size); 2739 return ERR_PTR(error); 2740} 2741EXPORT_SYMBOL_GPL(shmem_file_setup); 2742 2743/** 2744 * shmem_zero_setup - setup a shared anonymous mapping 2745 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2746 */ 2747int shmem_zero_setup(struct vm_area_struct *vma) 2748{ 2749 struct file *file; 2750 loff_t size = vma->vm_end - vma->vm_start; 2751 2752 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2753 if (IS_ERR(file)) 2754 return PTR_ERR(file); 2755 2756 if (vma->vm_file) 2757 fput(vma->vm_file); 2758 vma->vm_file = file; 2759 vma->vm_ops = &shmem_vm_ops; 2760 return 0; 2761} 2762