shmem.c revision 6a1a90ad1b0edb556a7550a6ef8a8756f0304dd5
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 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE) 771 && newsize != inode->i_size) { 772 struct page *page = NULL; 773 774 if (newsize < inode->i_size) { 775 /* 776 * If truncating down to a partial page, then 777 * if that page is already allocated, hold it 778 * in memory until the truncation is over, so 779 * truncate_partial_page cannnot miss it were 780 * it assigned to swap. 781 */ 782 if (newsize & (PAGE_CACHE_SIZE-1)) { 783 (void) shmem_getpage(inode, 784 newsize >> PAGE_CACHE_SHIFT, 785 &page, SGP_READ, NULL); 786 if (page) 787 unlock_page(page); 788 } 789 /* 790 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 791 * detect if any pages might have been added to cache 792 * after truncate_inode_pages. But we needn't bother 793 * if it's being fully truncated to zero-length: the 794 * nrpages check is efficient enough in that case. 795 */ 796 if (newsize) { 797 struct shmem_inode_info *info = SHMEM_I(inode); 798 spin_lock(&info->lock); 799 info->flags &= ~SHMEM_PAGEIN; 800 spin_unlock(&info->lock); 801 } 802 } 803 804 error = simple_setsize(inode, newsize); 805 if (page) 806 page_cache_release(page); 807 if (error) 808 return error; 809 shmem_truncate_range(inode, newsize, (loff_t)-1); 810 } 811 812 error = inode_change_ok(inode, attr); 813 if (!error) 814 setattr_copy(inode, attr); 815#ifdef CONFIG_TMPFS_POSIX_ACL 816 if (!error && (attr->ia_valid & ATTR_MODE)) 817 error = generic_acl_chmod(inode); 818#endif 819 return error; 820} 821 822static void shmem_delete_inode(struct inode *inode) 823{ 824 struct shmem_inode_info *info = SHMEM_I(inode); 825 826 if (inode->i_mapping->a_ops == &shmem_aops) { 827 truncate_inode_pages(inode->i_mapping, 0); 828 shmem_unacct_size(info->flags, inode->i_size); 829 inode->i_size = 0; 830 shmem_truncate_range(inode, 0, (loff_t)-1); 831 if (!list_empty(&info->swaplist)) { 832 mutex_lock(&shmem_swaplist_mutex); 833 list_del_init(&info->swaplist); 834 mutex_unlock(&shmem_swaplist_mutex); 835 } 836 } 837 BUG_ON(inode->i_blocks); 838 shmem_free_inode(inode->i_sb); 839 clear_inode(inode); 840} 841 842static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 843{ 844 swp_entry_t *ptr; 845 846 for (ptr = dir; ptr < edir; ptr++) { 847 if (ptr->val == entry.val) 848 return ptr - dir; 849 } 850 return -1; 851} 852 853static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 854{ 855 struct inode *inode; 856 unsigned long idx; 857 unsigned long size; 858 unsigned long limit; 859 unsigned long stage; 860 struct page **dir; 861 struct page *subdir; 862 swp_entry_t *ptr; 863 int offset; 864 int error; 865 866 idx = 0; 867 ptr = info->i_direct; 868 spin_lock(&info->lock); 869 if (!info->swapped) { 870 list_del_init(&info->swaplist); 871 goto lost2; 872 } 873 limit = info->next_index; 874 size = limit; 875 if (size > SHMEM_NR_DIRECT) 876 size = SHMEM_NR_DIRECT; 877 offset = shmem_find_swp(entry, ptr, ptr+size); 878 if (offset >= 0) 879 goto found; 880 if (!info->i_indirect) 881 goto lost2; 882 883 dir = shmem_dir_map(info->i_indirect); 884 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 885 886 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 887 if (unlikely(idx == stage)) { 888 shmem_dir_unmap(dir-1); 889 if (cond_resched_lock(&info->lock)) { 890 /* check it has not been truncated */ 891 if (limit > info->next_index) { 892 limit = info->next_index; 893 if (idx >= limit) 894 goto lost2; 895 } 896 } 897 dir = shmem_dir_map(info->i_indirect) + 898 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 899 while (!*dir) { 900 dir++; 901 idx += ENTRIES_PER_PAGEPAGE; 902 if (idx >= limit) 903 goto lost1; 904 } 905 stage = idx + ENTRIES_PER_PAGEPAGE; 906 subdir = *dir; 907 shmem_dir_unmap(dir); 908 dir = shmem_dir_map(subdir); 909 } 910 subdir = *dir; 911 if (subdir && page_private(subdir)) { 912 ptr = shmem_swp_map(subdir); 913 size = limit - idx; 914 if (size > ENTRIES_PER_PAGE) 915 size = ENTRIES_PER_PAGE; 916 offset = shmem_find_swp(entry, ptr, ptr+size); 917 shmem_swp_unmap(ptr); 918 if (offset >= 0) { 919 shmem_dir_unmap(dir); 920 goto found; 921 } 922 } 923 } 924lost1: 925 shmem_dir_unmap(dir-1); 926lost2: 927 spin_unlock(&info->lock); 928 return 0; 929found: 930 idx += offset; 931 inode = igrab(&info->vfs_inode); 932 spin_unlock(&info->lock); 933 934 /* 935 * Move _head_ to start search for next from here. 936 * But be careful: shmem_delete_inode checks list_empty without taking 937 * mutex, and there's an instant in list_move_tail when info->swaplist 938 * would appear empty, if it were the only one on shmem_swaplist. We 939 * could avoid doing it if inode NULL; or use this minor optimization. 940 */ 941 if (shmem_swaplist.next != &info->swaplist) 942 list_move_tail(&shmem_swaplist, &info->swaplist); 943 mutex_unlock(&shmem_swaplist_mutex); 944 945 error = 1; 946 if (!inode) 947 goto out; 948 /* 949 * Charge page using GFP_KERNEL while we can wait. 950 * Charged back to the user(not to caller) when swap account is used. 951 * add_to_page_cache() will be called with GFP_NOWAIT. 952 */ 953 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); 954 if (error) 955 goto out; 956 error = radix_tree_preload(GFP_KERNEL); 957 if (error) { 958 mem_cgroup_uncharge_cache_page(page); 959 goto out; 960 } 961 error = 1; 962 963 spin_lock(&info->lock); 964 ptr = shmem_swp_entry(info, idx, NULL); 965 if (ptr && ptr->val == entry.val) { 966 error = add_to_page_cache_locked(page, inode->i_mapping, 967 idx, GFP_NOWAIT); 968 /* does mem_cgroup_uncharge_cache_page on error */ 969 } else /* we must compensate for our precharge above */ 970 mem_cgroup_uncharge_cache_page(page); 971 972 if (error == -EEXIST) { 973 struct page *filepage = find_get_page(inode->i_mapping, idx); 974 error = 1; 975 if (filepage) { 976 /* 977 * There might be a more uptodate page coming down 978 * from a stacked writepage: forget our swappage if so. 979 */ 980 if (PageUptodate(filepage)) 981 error = 0; 982 page_cache_release(filepage); 983 } 984 } 985 if (!error) { 986 delete_from_swap_cache(page); 987 set_page_dirty(page); 988 info->flags |= SHMEM_PAGEIN; 989 shmem_swp_set(info, ptr, 0); 990 swap_free(entry); 991 error = 1; /* not an error, but entry was found */ 992 } 993 if (ptr) 994 shmem_swp_unmap(ptr); 995 spin_unlock(&info->lock); 996 radix_tree_preload_end(); 997out: 998 unlock_page(page); 999 page_cache_release(page); 1000 iput(inode); /* allows for NULL */ 1001 return error; 1002} 1003 1004/* 1005 * shmem_unuse() search for an eventually swapped out shmem page. 1006 */ 1007int shmem_unuse(swp_entry_t entry, struct page *page) 1008{ 1009 struct list_head *p, *next; 1010 struct shmem_inode_info *info; 1011 int found = 0; 1012 1013 mutex_lock(&shmem_swaplist_mutex); 1014 list_for_each_safe(p, next, &shmem_swaplist) { 1015 info = list_entry(p, struct shmem_inode_info, swaplist); 1016 found = shmem_unuse_inode(info, entry, page); 1017 cond_resched(); 1018 if (found) 1019 goto out; 1020 } 1021 mutex_unlock(&shmem_swaplist_mutex); 1022 /* 1023 * Can some race bring us here? We've been holding page lock, 1024 * so I think not; but would rather try again later than BUG() 1025 */ 1026 unlock_page(page); 1027 page_cache_release(page); 1028out: 1029 return (found < 0) ? found : 0; 1030} 1031 1032/* 1033 * Move the page from the page cache to the swap cache. 1034 */ 1035static int shmem_writepage(struct page *page, struct writeback_control *wbc) 1036{ 1037 struct shmem_inode_info *info; 1038 swp_entry_t *entry, swap; 1039 struct address_space *mapping; 1040 unsigned long index; 1041 struct inode *inode; 1042 1043 BUG_ON(!PageLocked(page)); 1044 mapping = page->mapping; 1045 index = page->index; 1046 inode = mapping->host; 1047 info = SHMEM_I(inode); 1048 if (info->flags & VM_LOCKED) 1049 goto redirty; 1050 if (!total_swap_pages) 1051 goto redirty; 1052 1053 /* 1054 * shmem_backing_dev_info's capabilities prevent regular writeback or 1055 * sync from ever calling shmem_writepage; but a stacking filesystem 1056 * may use the ->writepage of its underlying filesystem, in which case 1057 * tmpfs should write out to swap only in response to memory pressure, 1058 * and not for the writeback threads or sync. However, in those cases, 1059 * we do still want to check if there's a redundant swappage to be 1060 * discarded. 1061 */ 1062 if (wbc->for_reclaim) 1063 swap = get_swap_page(); 1064 else 1065 swap.val = 0; 1066 1067 spin_lock(&info->lock); 1068 if (index >= info->next_index) { 1069 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1070 goto unlock; 1071 } 1072 entry = shmem_swp_entry(info, index, NULL); 1073 if (entry->val) { 1074 /* 1075 * The more uptodate page coming down from a stacked 1076 * writepage should replace our old swappage. 1077 */ 1078 free_swap_and_cache(*entry); 1079 shmem_swp_set(info, entry, 0); 1080 } 1081 shmem_recalc_inode(inode); 1082 1083 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1084 remove_from_page_cache(page); 1085 shmem_swp_set(info, entry, swap.val); 1086 shmem_swp_unmap(entry); 1087 if (list_empty(&info->swaplist)) 1088 inode = igrab(inode); 1089 else 1090 inode = NULL; 1091 spin_unlock(&info->lock); 1092 swap_shmem_alloc(swap); 1093 BUG_ON(page_mapped(page)); 1094 page_cache_release(page); /* pagecache ref */ 1095 swap_writepage(page, wbc); 1096 if (inode) { 1097 mutex_lock(&shmem_swaplist_mutex); 1098 /* move instead of add in case we're racing */ 1099 list_move_tail(&info->swaplist, &shmem_swaplist); 1100 mutex_unlock(&shmem_swaplist_mutex); 1101 iput(inode); 1102 } 1103 return 0; 1104 } 1105 1106 shmem_swp_unmap(entry); 1107unlock: 1108 spin_unlock(&info->lock); 1109 /* 1110 * add_to_swap_cache() doesn't return -EEXIST, so we can safely 1111 * clear SWAP_HAS_CACHE flag. 1112 */ 1113 swapcache_free(swap, NULL); 1114redirty: 1115 set_page_dirty(page); 1116 if (wbc->for_reclaim) 1117 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1118 unlock_page(page); 1119 return 0; 1120} 1121 1122#ifdef CONFIG_NUMA 1123#ifdef CONFIG_TMPFS 1124static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) 1125{ 1126 char buffer[64]; 1127 1128 if (!mpol || mpol->mode == MPOL_DEFAULT) 1129 return; /* show nothing */ 1130 1131 mpol_to_str(buffer, sizeof(buffer), mpol, 1); 1132 1133 seq_printf(seq, ",mpol=%s", buffer); 1134} 1135 1136static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1137{ 1138 struct mempolicy *mpol = NULL; 1139 if (sbinfo->mpol) { 1140 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ 1141 mpol = sbinfo->mpol; 1142 mpol_get(mpol); 1143 spin_unlock(&sbinfo->stat_lock); 1144 } 1145 return mpol; 1146} 1147#endif /* CONFIG_TMPFS */ 1148 1149static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1150 struct shmem_inode_info *info, unsigned long idx) 1151{ 1152 struct mempolicy mpol, *spol; 1153 struct vm_area_struct pvma; 1154 struct page *page; 1155 1156 spol = mpol_cond_copy(&mpol, 1157 mpol_shared_policy_lookup(&info->policy, idx)); 1158 1159 /* Create a pseudo vma that just contains the policy */ 1160 pvma.vm_start = 0; 1161 pvma.vm_pgoff = idx; 1162 pvma.vm_ops = NULL; 1163 pvma.vm_policy = spol; 1164 page = swapin_readahead(entry, gfp, &pvma, 0); 1165 return page; 1166} 1167 1168static struct page *shmem_alloc_page(gfp_t gfp, 1169 struct shmem_inode_info *info, unsigned long idx) 1170{ 1171 struct vm_area_struct pvma; 1172 1173 /* Create a pseudo vma that just contains the policy */ 1174 pvma.vm_start = 0; 1175 pvma.vm_pgoff = idx; 1176 pvma.vm_ops = NULL; 1177 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1178 1179 /* 1180 * alloc_page_vma() will drop the shared policy reference 1181 */ 1182 return alloc_page_vma(gfp, &pvma, 0); 1183} 1184#else /* !CONFIG_NUMA */ 1185#ifdef CONFIG_TMPFS 1186static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) 1187{ 1188} 1189#endif /* CONFIG_TMPFS */ 1190 1191static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1192 struct shmem_inode_info *info, unsigned long idx) 1193{ 1194 return swapin_readahead(entry, gfp, NULL, 0); 1195} 1196 1197static inline struct page *shmem_alloc_page(gfp_t gfp, 1198 struct shmem_inode_info *info, unsigned long idx) 1199{ 1200 return alloc_page(gfp); 1201} 1202#endif /* CONFIG_NUMA */ 1203 1204#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) 1205static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1206{ 1207 return NULL; 1208} 1209#endif 1210 1211/* 1212 * shmem_getpage - either get the page from swap or allocate a new one 1213 * 1214 * If we allocate a new one we do not mark it dirty. That's up to the 1215 * vm. If we swap it in we mark it dirty since we also free the swap 1216 * entry since a page cannot live in both the swap and page cache 1217 */ 1218static int shmem_getpage(struct inode *inode, unsigned long idx, 1219 struct page **pagep, enum sgp_type sgp, int *type) 1220{ 1221 struct address_space *mapping = inode->i_mapping; 1222 struct shmem_inode_info *info = SHMEM_I(inode); 1223 struct shmem_sb_info *sbinfo; 1224 struct page *filepage = *pagep; 1225 struct page *swappage; 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 error = 0; 1251 gfp = mapping_gfp_mask(mapping); 1252 if (!filepage) { 1253 /* 1254 * Try to preload while we can wait, to not make a habit of 1255 * draining atomic reserves; but don't latch on to this cpu. 1256 */ 1257 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1258 if (error) 1259 goto failed; 1260 radix_tree_preload_end(); 1261 } 1262 1263 spin_lock(&info->lock); 1264 shmem_recalc_inode(inode); 1265 entry = shmem_swp_alloc(info, idx, sgp); 1266 if (IS_ERR(entry)) { 1267 spin_unlock(&info->lock); 1268 error = PTR_ERR(entry); 1269 goto failed; 1270 } 1271 swap = *entry; 1272 1273 if (swap.val) { 1274 /* Look it up and read it in.. */ 1275 swappage = lookup_swap_cache(swap); 1276 if (!swappage) { 1277 shmem_swp_unmap(entry); 1278 /* here we actually do the io */ 1279 if (type && !(*type & VM_FAULT_MAJOR)) { 1280 __count_vm_event(PGMAJFAULT); 1281 *type |= VM_FAULT_MAJOR; 1282 } 1283 spin_unlock(&info->lock); 1284 swappage = shmem_swapin(swap, gfp, info, idx); 1285 if (!swappage) { 1286 spin_lock(&info->lock); 1287 entry = shmem_swp_alloc(info, idx, sgp); 1288 if (IS_ERR(entry)) 1289 error = PTR_ERR(entry); 1290 else { 1291 if (entry->val == swap.val) 1292 error = -ENOMEM; 1293 shmem_swp_unmap(entry); 1294 } 1295 spin_unlock(&info->lock); 1296 if (error) 1297 goto failed; 1298 goto repeat; 1299 } 1300 wait_on_page_locked(swappage); 1301 page_cache_release(swappage); 1302 goto repeat; 1303 } 1304 1305 /* We have to do this with page locked to prevent races */ 1306 if (!trylock_page(swappage)) { 1307 shmem_swp_unmap(entry); 1308 spin_unlock(&info->lock); 1309 wait_on_page_locked(swappage); 1310 page_cache_release(swappage); 1311 goto repeat; 1312 } 1313 if (PageWriteback(swappage)) { 1314 shmem_swp_unmap(entry); 1315 spin_unlock(&info->lock); 1316 wait_on_page_writeback(swappage); 1317 unlock_page(swappage); 1318 page_cache_release(swappage); 1319 goto repeat; 1320 } 1321 if (!PageUptodate(swappage)) { 1322 shmem_swp_unmap(entry); 1323 spin_unlock(&info->lock); 1324 unlock_page(swappage); 1325 page_cache_release(swappage); 1326 error = -EIO; 1327 goto failed; 1328 } 1329 1330 if (filepage) { 1331 shmem_swp_set(info, entry, 0); 1332 shmem_swp_unmap(entry); 1333 delete_from_swap_cache(swappage); 1334 spin_unlock(&info->lock); 1335 copy_highpage(filepage, swappage); 1336 unlock_page(swappage); 1337 page_cache_release(swappage); 1338 flush_dcache_page(filepage); 1339 SetPageUptodate(filepage); 1340 set_page_dirty(filepage); 1341 swap_free(swap); 1342 } else if (!(error = add_to_page_cache_locked(swappage, mapping, 1343 idx, GFP_NOWAIT))) { 1344 info->flags |= SHMEM_PAGEIN; 1345 shmem_swp_set(info, entry, 0); 1346 shmem_swp_unmap(entry); 1347 delete_from_swap_cache(swappage); 1348 spin_unlock(&info->lock); 1349 filepage = swappage; 1350 set_page_dirty(filepage); 1351 swap_free(swap); 1352 } else { 1353 shmem_swp_unmap(entry); 1354 spin_unlock(&info->lock); 1355 if (error == -ENOMEM) { 1356 /* 1357 * reclaim from proper memory cgroup and 1358 * call memcg's OOM if needed. 1359 */ 1360 error = mem_cgroup_shmem_charge_fallback( 1361 swappage, 1362 current->mm, 1363 gfp); 1364 if (error) { 1365 unlock_page(swappage); 1366 page_cache_release(swappage); 1367 goto failed; 1368 } 1369 } 1370 unlock_page(swappage); 1371 page_cache_release(swappage); 1372 goto repeat; 1373 } 1374 } else if (sgp == SGP_READ && !filepage) { 1375 shmem_swp_unmap(entry); 1376 filepage = find_get_page(mapping, idx); 1377 if (filepage && 1378 (!PageUptodate(filepage) || !trylock_page(filepage))) { 1379 spin_unlock(&info->lock); 1380 wait_on_page_locked(filepage); 1381 page_cache_release(filepage); 1382 filepage = NULL; 1383 goto repeat; 1384 } 1385 spin_unlock(&info->lock); 1386 } else { 1387 shmem_swp_unmap(entry); 1388 sbinfo = SHMEM_SB(inode->i_sb); 1389 if (sbinfo->max_blocks) { 1390 spin_lock(&sbinfo->stat_lock); 1391 if (sbinfo->free_blocks == 0 || 1392 shmem_acct_block(info->flags)) { 1393 spin_unlock(&sbinfo->stat_lock); 1394 spin_unlock(&info->lock); 1395 error = -ENOSPC; 1396 goto failed; 1397 } 1398 sbinfo->free_blocks--; 1399 inode->i_blocks += BLOCKS_PER_PAGE; 1400 spin_unlock(&sbinfo->stat_lock); 1401 } else if (shmem_acct_block(info->flags)) { 1402 spin_unlock(&info->lock); 1403 error = -ENOSPC; 1404 goto failed; 1405 } 1406 1407 if (!filepage) { 1408 int ret; 1409 1410 spin_unlock(&info->lock); 1411 filepage = shmem_alloc_page(gfp, info, idx); 1412 if (!filepage) { 1413 shmem_unacct_blocks(info->flags, 1); 1414 shmem_free_blocks(inode, 1); 1415 error = -ENOMEM; 1416 goto failed; 1417 } 1418 SetPageSwapBacked(filepage); 1419 1420 /* Precharge page while we can wait, compensate after */ 1421 error = mem_cgroup_cache_charge(filepage, current->mm, 1422 GFP_KERNEL); 1423 if (error) { 1424 page_cache_release(filepage); 1425 shmem_unacct_blocks(info->flags, 1); 1426 shmem_free_blocks(inode, 1); 1427 filepage = NULL; 1428 goto failed; 1429 } 1430 1431 spin_lock(&info->lock); 1432 entry = shmem_swp_alloc(info, idx, sgp); 1433 if (IS_ERR(entry)) 1434 error = PTR_ERR(entry); 1435 else { 1436 swap = *entry; 1437 shmem_swp_unmap(entry); 1438 } 1439 ret = error || swap.val; 1440 if (ret) 1441 mem_cgroup_uncharge_cache_page(filepage); 1442 else 1443 ret = add_to_page_cache_lru(filepage, mapping, 1444 idx, GFP_NOWAIT); 1445 /* 1446 * At add_to_page_cache_lru() failure, uncharge will 1447 * be done automatically. 1448 */ 1449 if (ret) { 1450 spin_unlock(&info->lock); 1451 page_cache_release(filepage); 1452 shmem_unacct_blocks(info->flags, 1); 1453 shmem_free_blocks(inode, 1); 1454 filepage = NULL; 1455 if (error) 1456 goto failed; 1457 goto repeat; 1458 } 1459 info->flags |= SHMEM_PAGEIN; 1460 } 1461 1462 info->alloced++; 1463 spin_unlock(&info->lock); 1464 clear_highpage(filepage); 1465 flush_dcache_page(filepage); 1466 SetPageUptodate(filepage); 1467 if (sgp == SGP_DIRTY) 1468 set_page_dirty(filepage); 1469 } 1470done: 1471 *pagep = filepage; 1472 return 0; 1473 1474failed: 1475 if (*pagep != filepage) { 1476 unlock_page(filepage); 1477 page_cache_release(filepage); 1478 } 1479 return error; 1480} 1481 1482static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1483{ 1484 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1485 int error; 1486 int ret; 1487 1488 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1489 return VM_FAULT_SIGBUS; 1490 1491 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1492 if (error) 1493 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1494 1495 return ret | VM_FAULT_LOCKED; 1496} 1497 1498#ifdef CONFIG_NUMA 1499static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1500{ 1501 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1502 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1503} 1504 1505static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1506 unsigned long addr) 1507{ 1508 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1509 unsigned long idx; 1510 1511 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1512 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1513} 1514#endif 1515 1516int shmem_lock(struct file *file, int lock, struct user_struct *user) 1517{ 1518 struct inode *inode = file->f_path.dentry->d_inode; 1519 struct shmem_inode_info *info = SHMEM_I(inode); 1520 int retval = -ENOMEM; 1521 1522 spin_lock(&info->lock); 1523 if (lock && !(info->flags & VM_LOCKED)) { 1524 if (!user_shm_lock(inode->i_size, user)) 1525 goto out_nomem; 1526 info->flags |= VM_LOCKED; 1527 mapping_set_unevictable(file->f_mapping); 1528 } 1529 if (!lock && (info->flags & VM_LOCKED) && user) { 1530 user_shm_unlock(inode->i_size, user); 1531 info->flags &= ~VM_LOCKED; 1532 mapping_clear_unevictable(file->f_mapping); 1533 scan_mapping_unevictable_pages(file->f_mapping); 1534 } 1535 retval = 0; 1536 1537out_nomem: 1538 spin_unlock(&info->lock); 1539 return retval; 1540} 1541 1542static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1543{ 1544 file_accessed(file); 1545 vma->vm_ops = &shmem_vm_ops; 1546 vma->vm_flags |= VM_CAN_NONLINEAR; 1547 return 0; 1548} 1549 1550static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, 1551 int mode, dev_t dev, unsigned long flags) 1552{ 1553 struct inode *inode; 1554 struct shmem_inode_info *info; 1555 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1556 1557 if (shmem_reserve_inode(sb)) 1558 return NULL; 1559 1560 inode = new_inode(sb); 1561 if (inode) { 1562 inode_init_owner(inode, dir, mode); 1563 inode->i_blocks = 0; 1564 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1565 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1566 inode->i_generation = get_seconds(); 1567 info = SHMEM_I(inode); 1568 memset(info, 0, (char *)inode - (char *)info); 1569 spin_lock_init(&info->lock); 1570 info->flags = flags & VM_NORESERVE; 1571 INIT_LIST_HEAD(&info->swaplist); 1572 cache_no_acl(inode); 1573 1574 switch (mode & S_IFMT) { 1575 default: 1576 inode->i_op = &shmem_special_inode_operations; 1577 init_special_inode(inode, mode, dev); 1578 break; 1579 case S_IFREG: 1580 inode->i_mapping->a_ops = &shmem_aops; 1581 inode->i_op = &shmem_inode_operations; 1582 inode->i_fop = &shmem_file_operations; 1583 mpol_shared_policy_init(&info->policy, 1584 shmem_get_sbmpol(sbinfo)); 1585 break; 1586 case S_IFDIR: 1587 inc_nlink(inode); 1588 /* Some things misbehave if size == 0 on a directory */ 1589 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1590 inode->i_op = &shmem_dir_inode_operations; 1591 inode->i_fop = &simple_dir_operations; 1592 break; 1593 case S_IFLNK: 1594 /* 1595 * Must not load anything in the rbtree, 1596 * mpol_free_shared_policy will not be called. 1597 */ 1598 mpol_shared_policy_init(&info->policy, NULL); 1599 break; 1600 } 1601 } else 1602 shmem_free_inode(sb); 1603 return inode; 1604} 1605 1606#ifdef CONFIG_TMPFS 1607static const struct inode_operations shmem_symlink_inode_operations; 1608static const struct inode_operations shmem_symlink_inline_operations; 1609 1610/* 1611 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1612 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1613 * below the loop driver, in the generic fashion that many filesystems support. 1614 */ 1615static int shmem_readpage(struct file *file, struct page *page) 1616{ 1617 struct inode *inode = page->mapping->host; 1618 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1619 unlock_page(page); 1620 return error; 1621} 1622 1623static int 1624shmem_write_begin(struct file *file, struct address_space *mapping, 1625 loff_t pos, unsigned len, unsigned flags, 1626 struct page **pagep, void **fsdata) 1627{ 1628 struct inode *inode = mapping->host; 1629 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1630 *pagep = NULL; 1631 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1632} 1633 1634static int 1635shmem_write_end(struct file *file, struct address_space *mapping, 1636 loff_t pos, unsigned len, unsigned copied, 1637 struct page *page, void *fsdata) 1638{ 1639 struct inode *inode = mapping->host; 1640 1641 if (pos + copied > inode->i_size) 1642 i_size_write(inode, pos + copied); 1643 1644 set_page_dirty(page); 1645 unlock_page(page); 1646 page_cache_release(page); 1647 1648 return copied; 1649} 1650 1651static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1652{ 1653 struct inode *inode = filp->f_path.dentry->d_inode; 1654 struct address_space *mapping = inode->i_mapping; 1655 unsigned long index, offset; 1656 enum sgp_type sgp = SGP_READ; 1657 1658 /* 1659 * Might this read be for a stacking filesystem? Then when reading 1660 * holes of a sparse file, we actually need to allocate those pages, 1661 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1662 */ 1663 if (segment_eq(get_fs(), KERNEL_DS)) 1664 sgp = SGP_DIRTY; 1665 1666 index = *ppos >> PAGE_CACHE_SHIFT; 1667 offset = *ppos & ~PAGE_CACHE_MASK; 1668 1669 for (;;) { 1670 struct page *page = NULL; 1671 unsigned long end_index, nr, ret; 1672 loff_t i_size = i_size_read(inode); 1673 1674 end_index = i_size >> PAGE_CACHE_SHIFT; 1675 if (index > end_index) 1676 break; 1677 if (index == end_index) { 1678 nr = i_size & ~PAGE_CACHE_MASK; 1679 if (nr <= offset) 1680 break; 1681 } 1682 1683 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1684 if (desc->error) { 1685 if (desc->error == -EINVAL) 1686 desc->error = 0; 1687 break; 1688 } 1689 if (page) 1690 unlock_page(page); 1691 1692 /* 1693 * We must evaluate after, since reads (unlike writes) 1694 * are called without i_mutex protection against truncate 1695 */ 1696 nr = PAGE_CACHE_SIZE; 1697 i_size = i_size_read(inode); 1698 end_index = i_size >> PAGE_CACHE_SHIFT; 1699 if (index == end_index) { 1700 nr = i_size & ~PAGE_CACHE_MASK; 1701 if (nr <= offset) { 1702 if (page) 1703 page_cache_release(page); 1704 break; 1705 } 1706 } 1707 nr -= offset; 1708 1709 if (page) { 1710 /* 1711 * If users can be writing to this page using arbitrary 1712 * virtual addresses, take care about potential aliasing 1713 * before reading the page on the kernel side. 1714 */ 1715 if (mapping_writably_mapped(mapping)) 1716 flush_dcache_page(page); 1717 /* 1718 * Mark the page accessed if we read the beginning. 1719 */ 1720 if (!offset) 1721 mark_page_accessed(page); 1722 } else { 1723 page = ZERO_PAGE(0); 1724 page_cache_get(page); 1725 } 1726 1727 /* 1728 * Ok, we have the page, and it's up-to-date, so 1729 * now we can copy it to user space... 1730 * 1731 * The actor routine returns how many bytes were actually used.. 1732 * NOTE! This may not be the same as how much of a user buffer 1733 * we filled up (we may be padding etc), so we can only update 1734 * "pos" here (the actor routine has to update the user buffer 1735 * pointers and the remaining count). 1736 */ 1737 ret = actor(desc, page, offset, nr); 1738 offset += ret; 1739 index += offset >> PAGE_CACHE_SHIFT; 1740 offset &= ~PAGE_CACHE_MASK; 1741 1742 page_cache_release(page); 1743 if (ret != nr || !desc->count) 1744 break; 1745 1746 cond_resched(); 1747 } 1748 1749 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1750 file_accessed(filp); 1751} 1752 1753static ssize_t shmem_file_aio_read(struct kiocb *iocb, 1754 const struct iovec *iov, unsigned long nr_segs, loff_t pos) 1755{ 1756 struct file *filp = iocb->ki_filp; 1757 ssize_t retval; 1758 unsigned long seg; 1759 size_t count; 1760 loff_t *ppos = &iocb->ki_pos; 1761 1762 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); 1763 if (retval) 1764 return retval; 1765 1766 for (seg = 0; seg < nr_segs; seg++) { 1767 read_descriptor_t desc; 1768 1769 desc.written = 0; 1770 desc.arg.buf = iov[seg].iov_base; 1771 desc.count = iov[seg].iov_len; 1772 if (desc.count == 0) 1773 continue; 1774 desc.error = 0; 1775 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1776 retval += desc.written; 1777 if (desc.error) { 1778 retval = retval ?: desc.error; 1779 break; 1780 } 1781 if (desc.count > 0) 1782 break; 1783 } 1784 return retval; 1785} 1786 1787static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1788{ 1789 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1790 1791 buf->f_type = TMPFS_MAGIC; 1792 buf->f_bsize = PAGE_CACHE_SIZE; 1793 buf->f_namelen = NAME_MAX; 1794 spin_lock(&sbinfo->stat_lock); 1795 if (sbinfo->max_blocks) { 1796 buf->f_blocks = sbinfo->max_blocks; 1797 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1798 } 1799 if (sbinfo->max_inodes) { 1800 buf->f_files = sbinfo->max_inodes; 1801 buf->f_ffree = sbinfo->free_inodes; 1802 } 1803 /* else leave those fields 0 like simple_statfs */ 1804 spin_unlock(&sbinfo->stat_lock); 1805 return 0; 1806} 1807 1808/* 1809 * File creation. Allocate an inode, and we're done.. 1810 */ 1811static int 1812shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1813{ 1814 struct inode *inode; 1815 int error = -ENOSPC; 1816 1817 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); 1818 if (inode) { 1819 error = security_inode_init_security(inode, dir, NULL, NULL, 1820 NULL); 1821 if (error) { 1822 if (error != -EOPNOTSUPP) { 1823 iput(inode); 1824 return error; 1825 } 1826 } 1827#ifdef CONFIG_TMPFS_POSIX_ACL 1828 error = generic_acl_init(inode, dir); 1829 if (error) { 1830 iput(inode); 1831 return error; 1832 } 1833#else 1834 error = 0; 1835#endif 1836 dir->i_size += BOGO_DIRENT_SIZE; 1837 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1838 d_instantiate(dentry, inode); 1839 dget(dentry); /* Extra count - pin the dentry in core */ 1840 } 1841 return error; 1842} 1843 1844static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1845{ 1846 int error; 1847 1848 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1849 return error; 1850 inc_nlink(dir); 1851 return 0; 1852} 1853 1854static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1855 struct nameidata *nd) 1856{ 1857 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1858} 1859 1860/* 1861 * Link a file.. 1862 */ 1863static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1864{ 1865 struct inode *inode = old_dentry->d_inode; 1866 int ret; 1867 1868 /* 1869 * No ordinary (disk based) filesystem counts links as inodes; 1870 * but each new link needs a new dentry, pinning lowmem, and 1871 * tmpfs dentries cannot be pruned until they are unlinked. 1872 */ 1873 ret = shmem_reserve_inode(inode->i_sb); 1874 if (ret) 1875 goto out; 1876 1877 dir->i_size += BOGO_DIRENT_SIZE; 1878 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1879 inc_nlink(inode); 1880 atomic_inc(&inode->i_count); /* New dentry reference */ 1881 dget(dentry); /* Extra pinning count for the created dentry */ 1882 d_instantiate(dentry, inode); 1883out: 1884 return ret; 1885} 1886 1887static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1888{ 1889 struct inode *inode = dentry->d_inode; 1890 1891 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1892 shmem_free_inode(inode->i_sb); 1893 1894 dir->i_size -= BOGO_DIRENT_SIZE; 1895 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1896 drop_nlink(inode); 1897 dput(dentry); /* Undo the count from "create" - this does all the work */ 1898 return 0; 1899} 1900 1901static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1902{ 1903 if (!simple_empty(dentry)) 1904 return -ENOTEMPTY; 1905 1906 drop_nlink(dentry->d_inode); 1907 drop_nlink(dir); 1908 return shmem_unlink(dir, dentry); 1909} 1910 1911/* 1912 * The VFS layer already does all the dentry stuff for rename, 1913 * we just have to decrement the usage count for the target if 1914 * it exists so that the VFS layer correctly free's it when it 1915 * gets overwritten. 1916 */ 1917static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1918{ 1919 struct inode *inode = old_dentry->d_inode; 1920 int they_are_dirs = S_ISDIR(inode->i_mode); 1921 1922 if (!simple_empty(new_dentry)) 1923 return -ENOTEMPTY; 1924 1925 if (new_dentry->d_inode) { 1926 (void) shmem_unlink(new_dir, new_dentry); 1927 if (they_are_dirs) 1928 drop_nlink(old_dir); 1929 } else if (they_are_dirs) { 1930 drop_nlink(old_dir); 1931 inc_nlink(new_dir); 1932 } 1933 1934 old_dir->i_size -= BOGO_DIRENT_SIZE; 1935 new_dir->i_size += BOGO_DIRENT_SIZE; 1936 old_dir->i_ctime = old_dir->i_mtime = 1937 new_dir->i_ctime = new_dir->i_mtime = 1938 inode->i_ctime = CURRENT_TIME; 1939 return 0; 1940} 1941 1942static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1943{ 1944 int error; 1945 int len; 1946 struct inode *inode; 1947 struct page *page = NULL; 1948 char *kaddr; 1949 struct shmem_inode_info *info; 1950 1951 len = strlen(symname) + 1; 1952 if (len > PAGE_CACHE_SIZE) 1953 return -ENAMETOOLONG; 1954 1955 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); 1956 if (!inode) 1957 return -ENOSPC; 1958 1959 error = security_inode_init_security(inode, dir, NULL, NULL, 1960 NULL); 1961 if (error) { 1962 if (error != -EOPNOTSUPP) { 1963 iput(inode); 1964 return error; 1965 } 1966 error = 0; 1967 } 1968 1969 info = SHMEM_I(inode); 1970 inode->i_size = len-1; 1971 if (len <= (char *)inode - (char *)info) { 1972 /* do it inline */ 1973 memcpy(info, symname, len); 1974 inode->i_op = &shmem_symlink_inline_operations; 1975 } else { 1976 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1977 if (error) { 1978 iput(inode); 1979 return error; 1980 } 1981 inode->i_mapping->a_ops = &shmem_aops; 1982 inode->i_op = &shmem_symlink_inode_operations; 1983 kaddr = kmap_atomic(page, KM_USER0); 1984 memcpy(kaddr, symname, len); 1985 kunmap_atomic(kaddr, KM_USER0); 1986 set_page_dirty(page); 1987 unlock_page(page); 1988 page_cache_release(page); 1989 } 1990 dir->i_size += BOGO_DIRENT_SIZE; 1991 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1992 d_instantiate(dentry, inode); 1993 dget(dentry); 1994 return 0; 1995} 1996 1997static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1998{ 1999 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 2000 return NULL; 2001} 2002 2003static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 2004{ 2005 struct page *page = NULL; 2006 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 2007 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 2008 if (page) 2009 unlock_page(page); 2010 return page; 2011} 2012 2013static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 2014{ 2015 if (!IS_ERR(nd_get_link(nd))) { 2016 struct page *page = cookie; 2017 kunmap(page); 2018 mark_page_accessed(page); 2019 page_cache_release(page); 2020 } 2021} 2022 2023static const struct inode_operations shmem_symlink_inline_operations = { 2024 .readlink = generic_readlink, 2025 .follow_link = shmem_follow_link_inline, 2026}; 2027 2028static const struct inode_operations shmem_symlink_inode_operations = { 2029 .readlink = generic_readlink, 2030 .follow_link = shmem_follow_link, 2031 .put_link = shmem_put_link, 2032}; 2033 2034#ifdef CONFIG_TMPFS_POSIX_ACL 2035/* 2036 * Superblocks without xattr inode operations will get security.* xattr 2037 * support from the VFS "for free". As soon as we have any other xattrs 2038 * like ACLs, we also need to implement the security.* handlers at 2039 * filesystem level, though. 2040 */ 2041 2042static size_t shmem_xattr_security_list(struct dentry *dentry, char *list, 2043 size_t list_len, const char *name, 2044 size_t name_len, int handler_flags) 2045{ 2046 return security_inode_listsecurity(dentry->d_inode, list, list_len); 2047} 2048 2049static int shmem_xattr_security_get(struct dentry *dentry, const char *name, 2050 void *buffer, size_t size, int handler_flags) 2051{ 2052 if (strcmp(name, "") == 0) 2053 return -EINVAL; 2054 return xattr_getsecurity(dentry->d_inode, name, buffer, size); 2055} 2056 2057static int shmem_xattr_security_set(struct dentry *dentry, const char *name, 2058 const void *value, size_t size, int flags, int handler_flags) 2059{ 2060 if (strcmp(name, "") == 0) 2061 return -EINVAL; 2062 return security_inode_setsecurity(dentry->d_inode, name, value, 2063 size, flags); 2064} 2065 2066static const struct xattr_handler shmem_xattr_security_handler = { 2067 .prefix = XATTR_SECURITY_PREFIX, 2068 .list = shmem_xattr_security_list, 2069 .get = shmem_xattr_security_get, 2070 .set = shmem_xattr_security_set, 2071}; 2072 2073static const struct xattr_handler *shmem_xattr_handlers[] = { 2074 &generic_acl_access_handler, 2075 &generic_acl_default_handler, 2076 &shmem_xattr_security_handler, 2077 NULL 2078}; 2079#endif 2080 2081static struct dentry *shmem_get_parent(struct dentry *child) 2082{ 2083 return ERR_PTR(-ESTALE); 2084} 2085 2086static int shmem_match(struct inode *ino, void *vfh) 2087{ 2088 __u32 *fh = vfh; 2089 __u64 inum = fh[2]; 2090 inum = (inum << 32) | fh[1]; 2091 return ino->i_ino == inum && fh[0] == ino->i_generation; 2092} 2093 2094static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2095 struct fid *fid, int fh_len, int fh_type) 2096{ 2097 struct inode *inode; 2098 struct dentry *dentry = NULL; 2099 u64 inum = fid->raw[2]; 2100 inum = (inum << 32) | fid->raw[1]; 2101 2102 if (fh_len < 3) 2103 return NULL; 2104 2105 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2106 shmem_match, fid->raw); 2107 if (inode) { 2108 dentry = d_find_alias(inode); 2109 iput(inode); 2110 } 2111 2112 return dentry; 2113} 2114 2115static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2116 int connectable) 2117{ 2118 struct inode *inode = dentry->d_inode; 2119 2120 if (*len < 3) 2121 return 255; 2122 2123 if (hlist_unhashed(&inode->i_hash)) { 2124 /* Unfortunately insert_inode_hash is not idempotent, 2125 * so as we hash inodes here rather than at creation 2126 * time, we need a lock to ensure we only try 2127 * to do it once 2128 */ 2129 static DEFINE_SPINLOCK(lock); 2130 spin_lock(&lock); 2131 if (hlist_unhashed(&inode->i_hash)) 2132 __insert_inode_hash(inode, 2133 inode->i_ino + inode->i_generation); 2134 spin_unlock(&lock); 2135 } 2136 2137 fh[0] = inode->i_generation; 2138 fh[1] = inode->i_ino; 2139 fh[2] = ((__u64)inode->i_ino) >> 32; 2140 2141 *len = 3; 2142 return 1; 2143} 2144 2145static const struct export_operations shmem_export_ops = { 2146 .get_parent = shmem_get_parent, 2147 .encode_fh = shmem_encode_fh, 2148 .fh_to_dentry = shmem_fh_to_dentry, 2149}; 2150 2151static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 2152 bool remount) 2153{ 2154 char *this_char, *value, *rest; 2155 2156 while (options != NULL) { 2157 this_char = options; 2158 for (;;) { 2159 /* 2160 * NUL-terminate this option: unfortunately, 2161 * mount options form a comma-separated list, 2162 * but mpol's nodelist may also contain commas. 2163 */ 2164 options = strchr(options, ','); 2165 if (options == NULL) 2166 break; 2167 options++; 2168 if (!isdigit(*options)) { 2169 options[-1] = '\0'; 2170 break; 2171 } 2172 } 2173 if (!*this_char) 2174 continue; 2175 if ((value = strchr(this_char,'=')) != NULL) { 2176 *value++ = 0; 2177 } else { 2178 printk(KERN_ERR 2179 "tmpfs: No value for mount option '%s'\n", 2180 this_char); 2181 return 1; 2182 } 2183 2184 if (!strcmp(this_char,"size")) { 2185 unsigned long long size; 2186 size = memparse(value,&rest); 2187 if (*rest == '%') { 2188 size <<= PAGE_SHIFT; 2189 size *= totalram_pages; 2190 do_div(size, 100); 2191 rest++; 2192 } 2193 if (*rest) 2194 goto bad_val; 2195 sbinfo->max_blocks = 2196 DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2197 } else if (!strcmp(this_char,"nr_blocks")) { 2198 sbinfo->max_blocks = memparse(value, &rest); 2199 if (*rest) 2200 goto bad_val; 2201 } else if (!strcmp(this_char,"nr_inodes")) { 2202 sbinfo->max_inodes = memparse(value, &rest); 2203 if (*rest) 2204 goto bad_val; 2205 } else if (!strcmp(this_char,"mode")) { 2206 if (remount) 2207 continue; 2208 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; 2209 if (*rest) 2210 goto bad_val; 2211 } else if (!strcmp(this_char,"uid")) { 2212 if (remount) 2213 continue; 2214 sbinfo->uid = simple_strtoul(value, &rest, 0); 2215 if (*rest) 2216 goto bad_val; 2217 } else if (!strcmp(this_char,"gid")) { 2218 if (remount) 2219 continue; 2220 sbinfo->gid = simple_strtoul(value, &rest, 0); 2221 if (*rest) 2222 goto bad_val; 2223 } else if (!strcmp(this_char,"mpol")) { 2224 if (mpol_parse_str(value, &sbinfo->mpol, 1)) 2225 goto bad_val; 2226 } else { 2227 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2228 this_char); 2229 return 1; 2230 } 2231 } 2232 return 0; 2233 2234bad_val: 2235 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2236 value, this_char); 2237 return 1; 2238 2239} 2240 2241static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2242{ 2243 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2244 struct shmem_sb_info config = *sbinfo; 2245 unsigned long blocks; 2246 unsigned long inodes; 2247 int error = -EINVAL; 2248 2249 if (shmem_parse_options(data, &config, true)) 2250 return error; 2251 2252 spin_lock(&sbinfo->stat_lock); 2253 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2254 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2255 if (config.max_blocks < blocks) 2256 goto out; 2257 if (config.max_inodes < inodes) 2258 goto out; 2259 /* 2260 * Those tests also disallow limited->unlimited while any are in 2261 * use, so i_blocks will always be zero when max_blocks is zero; 2262 * but we must separately disallow unlimited->limited, because 2263 * in that case we have no record of how much is already in use. 2264 */ 2265 if (config.max_blocks && !sbinfo->max_blocks) 2266 goto out; 2267 if (config.max_inodes && !sbinfo->max_inodes) 2268 goto out; 2269 2270 error = 0; 2271 sbinfo->max_blocks = config.max_blocks; 2272 sbinfo->free_blocks = config.max_blocks - blocks; 2273 sbinfo->max_inodes = config.max_inodes; 2274 sbinfo->free_inodes = config.max_inodes - inodes; 2275 2276 mpol_put(sbinfo->mpol); 2277 sbinfo->mpol = config.mpol; /* transfers initial ref */ 2278out: 2279 spin_unlock(&sbinfo->stat_lock); 2280 return error; 2281} 2282 2283static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) 2284{ 2285 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); 2286 2287 if (sbinfo->max_blocks != shmem_default_max_blocks()) 2288 seq_printf(seq, ",size=%luk", 2289 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); 2290 if (sbinfo->max_inodes != shmem_default_max_inodes()) 2291 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); 2292 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) 2293 seq_printf(seq, ",mode=%03o", sbinfo->mode); 2294 if (sbinfo->uid != 0) 2295 seq_printf(seq, ",uid=%u", sbinfo->uid); 2296 if (sbinfo->gid != 0) 2297 seq_printf(seq, ",gid=%u", sbinfo->gid); 2298 shmem_show_mpol(seq, sbinfo->mpol); 2299 return 0; 2300} 2301#endif /* CONFIG_TMPFS */ 2302 2303static void shmem_put_super(struct super_block *sb) 2304{ 2305 kfree(sb->s_fs_info); 2306 sb->s_fs_info = NULL; 2307} 2308 2309int shmem_fill_super(struct super_block *sb, void *data, int silent) 2310{ 2311 struct inode *inode; 2312 struct dentry *root; 2313 struct shmem_sb_info *sbinfo; 2314 int err = -ENOMEM; 2315 2316 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2317 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), 2318 L1_CACHE_BYTES), GFP_KERNEL); 2319 if (!sbinfo) 2320 return -ENOMEM; 2321 2322 sbinfo->mode = S_IRWXUGO | S_ISVTX; 2323 sbinfo->uid = current_fsuid(); 2324 sbinfo->gid = current_fsgid(); 2325 sb->s_fs_info = sbinfo; 2326 2327#ifdef CONFIG_TMPFS 2328 /* 2329 * Per default we only allow half of the physical ram per 2330 * tmpfs instance, limiting inodes to one per page of lowmem; 2331 * but the internal instance is left unlimited. 2332 */ 2333 if (!(sb->s_flags & MS_NOUSER)) { 2334 sbinfo->max_blocks = shmem_default_max_blocks(); 2335 sbinfo->max_inodes = shmem_default_max_inodes(); 2336 if (shmem_parse_options(data, sbinfo, false)) { 2337 err = -EINVAL; 2338 goto failed; 2339 } 2340 } 2341 sb->s_export_op = &shmem_export_ops; 2342#else 2343 sb->s_flags |= MS_NOUSER; 2344#endif 2345 2346 spin_lock_init(&sbinfo->stat_lock); 2347 sbinfo->free_blocks = sbinfo->max_blocks; 2348 sbinfo->free_inodes = sbinfo->max_inodes; 2349 2350 sb->s_maxbytes = SHMEM_MAX_BYTES; 2351 sb->s_blocksize = PAGE_CACHE_SIZE; 2352 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2353 sb->s_magic = TMPFS_MAGIC; 2354 sb->s_op = &shmem_ops; 2355 sb->s_time_gran = 1; 2356#ifdef CONFIG_TMPFS_POSIX_ACL 2357 sb->s_xattr = shmem_xattr_handlers; 2358 sb->s_flags |= MS_POSIXACL; 2359#endif 2360 2361 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); 2362 if (!inode) 2363 goto failed; 2364 inode->i_uid = sbinfo->uid; 2365 inode->i_gid = sbinfo->gid; 2366 root = d_alloc_root(inode); 2367 if (!root) 2368 goto failed_iput; 2369 sb->s_root = root; 2370 return 0; 2371 2372failed_iput: 2373 iput(inode); 2374failed: 2375 shmem_put_super(sb); 2376 return err; 2377} 2378 2379static struct kmem_cache *shmem_inode_cachep; 2380 2381static struct inode *shmem_alloc_inode(struct super_block *sb) 2382{ 2383 struct shmem_inode_info *p; 2384 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2385 if (!p) 2386 return NULL; 2387 return &p->vfs_inode; 2388} 2389 2390static void shmem_destroy_inode(struct inode *inode) 2391{ 2392 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2393 /* only struct inode is valid if it's an inline symlink */ 2394 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2395 } 2396 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2397} 2398 2399static void init_once(void *foo) 2400{ 2401 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2402 2403 inode_init_once(&p->vfs_inode); 2404} 2405 2406static int init_inodecache(void) 2407{ 2408 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2409 sizeof(struct shmem_inode_info), 2410 0, SLAB_PANIC, init_once); 2411 return 0; 2412} 2413 2414static void destroy_inodecache(void) 2415{ 2416 kmem_cache_destroy(shmem_inode_cachep); 2417} 2418 2419static const struct address_space_operations shmem_aops = { 2420 .writepage = shmem_writepage, 2421 .set_page_dirty = __set_page_dirty_no_writeback, 2422#ifdef CONFIG_TMPFS 2423 .readpage = shmem_readpage, 2424 .write_begin = shmem_write_begin, 2425 .write_end = shmem_write_end, 2426#endif 2427 .migratepage = migrate_page, 2428 .error_remove_page = generic_error_remove_page, 2429}; 2430 2431static const struct file_operations shmem_file_operations = { 2432 .mmap = shmem_mmap, 2433#ifdef CONFIG_TMPFS 2434 .llseek = generic_file_llseek, 2435 .read = do_sync_read, 2436 .write = do_sync_write, 2437 .aio_read = shmem_file_aio_read, 2438 .aio_write = generic_file_aio_write, 2439 .fsync = noop_fsync, 2440 .splice_read = generic_file_splice_read, 2441 .splice_write = generic_file_splice_write, 2442#endif 2443}; 2444 2445static const struct inode_operations shmem_inode_operations = { 2446 .setattr = shmem_notify_change, 2447 .truncate_range = shmem_truncate_range, 2448#ifdef CONFIG_TMPFS_POSIX_ACL 2449 .setxattr = generic_setxattr, 2450 .getxattr = generic_getxattr, 2451 .listxattr = generic_listxattr, 2452 .removexattr = generic_removexattr, 2453 .check_acl = generic_check_acl, 2454#endif 2455 2456}; 2457 2458static const struct inode_operations shmem_dir_inode_operations = { 2459#ifdef CONFIG_TMPFS 2460 .create = shmem_create, 2461 .lookup = simple_lookup, 2462 .link = shmem_link, 2463 .unlink = shmem_unlink, 2464 .symlink = shmem_symlink, 2465 .mkdir = shmem_mkdir, 2466 .rmdir = shmem_rmdir, 2467 .mknod = shmem_mknod, 2468 .rename = shmem_rename, 2469#endif 2470#ifdef CONFIG_TMPFS_POSIX_ACL 2471 .setattr = shmem_notify_change, 2472 .setxattr = generic_setxattr, 2473 .getxattr = generic_getxattr, 2474 .listxattr = generic_listxattr, 2475 .removexattr = generic_removexattr, 2476 .check_acl = generic_check_acl, 2477#endif 2478}; 2479 2480static const struct inode_operations shmem_special_inode_operations = { 2481#ifdef CONFIG_TMPFS_POSIX_ACL 2482 .setattr = shmem_notify_change, 2483 .setxattr = generic_setxattr, 2484 .getxattr = generic_getxattr, 2485 .listxattr = generic_listxattr, 2486 .removexattr = generic_removexattr, 2487 .check_acl = generic_check_acl, 2488#endif 2489}; 2490 2491static const struct super_operations shmem_ops = { 2492 .alloc_inode = shmem_alloc_inode, 2493 .destroy_inode = shmem_destroy_inode, 2494#ifdef CONFIG_TMPFS 2495 .statfs = shmem_statfs, 2496 .remount_fs = shmem_remount_fs, 2497 .show_options = shmem_show_options, 2498#endif 2499 .delete_inode = shmem_delete_inode, 2500 .drop_inode = generic_delete_inode, 2501 .put_super = shmem_put_super, 2502}; 2503 2504static const struct vm_operations_struct shmem_vm_ops = { 2505 .fault = shmem_fault, 2506#ifdef CONFIG_NUMA 2507 .set_policy = shmem_set_policy, 2508 .get_policy = shmem_get_policy, 2509#endif 2510}; 2511 2512 2513static int shmem_get_sb(struct file_system_type *fs_type, 2514 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2515{ 2516 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2517} 2518 2519static struct file_system_type tmpfs_fs_type = { 2520 .owner = THIS_MODULE, 2521 .name = "tmpfs", 2522 .get_sb = shmem_get_sb, 2523 .kill_sb = kill_litter_super, 2524}; 2525 2526int __init init_tmpfs(void) 2527{ 2528 int error; 2529 2530 error = bdi_init(&shmem_backing_dev_info); 2531 if (error) 2532 goto out4; 2533 2534 error = init_inodecache(); 2535 if (error) 2536 goto out3; 2537 2538 error = register_filesystem(&tmpfs_fs_type); 2539 if (error) { 2540 printk(KERN_ERR "Could not register tmpfs\n"); 2541 goto out2; 2542 } 2543 2544 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2545 tmpfs_fs_type.name, NULL); 2546 if (IS_ERR(shm_mnt)) { 2547 error = PTR_ERR(shm_mnt); 2548 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2549 goto out1; 2550 } 2551 return 0; 2552 2553out1: 2554 unregister_filesystem(&tmpfs_fs_type); 2555out2: 2556 destroy_inodecache(); 2557out3: 2558 bdi_destroy(&shmem_backing_dev_info); 2559out4: 2560 shm_mnt = ERR_PTR(error); 2561 return error; 2562} 2563 2564#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2565/** 2566 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2567 * @inode: the inode to be searched 2568 * @pgoff: the offset to be searched 2569 * @pagep: the pointer for the found page to be stored 2570 * @ent: the pointer for the found swap entry to be stored 2571 * 2572 * If a page is found, refcount of it is incremented. Callers should handle 2573 * these refcount. 2574 */ 2575void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2576 struct page **pagep, swp_entry_t *ent) 2577{ 2578 swp_entry_t entry = { .val = 0 }, *ptr; 2579 struct page *page = NULL; 2580 struct shmem_inode_info *info = SHMEM_I(inode); 2581 2582 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2583 goto out; 2584 2585 spin_lock(&info->lock); 2586 ptr = shmem_swp_entry(info, pgoff, NULL); 2587#ifdef CONFIG_SWAP 2588 if (ptr && ptr->val) { 2589 entry.val = ptr->val; 2590 page = find_get_page(&swapper_space, entry.val); 2591 } else 2592#endif 2593 page = find_get_page(inode->i_mapping, pgoff); 2594 if (ptr) 2595 shmem_swp_unmap(ptr); 2596 spin_unlock(&info->lock); 2597out: 2598 *pagep = page; 2599 *ent = entry; 2600} 2601#endif 2602 2603#else /* !CONFIG_SHMEM */ 2604 2605/* 2606 * tiny-shmem: simple shmemfs and tmpfs using ramfs code 2607 * 2608 * This is intended for small system where the benefits of the full 2609 * shmem code (swap-backed and resource-limited) are outweighed by 2610 * their complexity. On systems without swap this code should be 2611 * effectively equivalent, but much lighter weight. 2612 */ 2613 2614#include <linux/ramfs.h> 2615 2616static struct file_system_type tmpfs_fs_type = { 2617 .name = "tmpfs", 2618 .get_sb = ramfs_get_sb, 2619 .kill_sb = kill_litter_super, 2620}; 2621 2622int __init init_tmpfs(void) 2623{ 2624 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); 2625 2626 shm_mnt = kern_mount(&tmpfs_fs_type); 2627 BUG_ON(IS_ERR(shm_mnt)); 2628 2629 return 0; 2630} 2631 2632int shmem_unuse(swp_entry_t entry, struct page *page) 2633{ 2634 return 0; 2635} 2636 2637int shmem_lock(struct file *file, int lock, struct user_struct *user) 2638{ 2639 return 0; 2640} 2641 2642#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2643/** 2644 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2645 * @inode: the inode to be searched 2646 * @pgoff: the offset to be searched 2647 * @pagep: the pointer for the found page to be stored 2648 * @ent: the pointer for the found swap entry to be stored 2649 * 2650 * If a page is found, refcount of it is incremented. Callers should handle 2651 * these refcount. 2652 */ 2653void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2654 struct page **pagep, swp_entry_t *ent) 2655{ 2656 struct page *page = NULL; 2657 2658 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2659 goto out; 2660 page = find_get_page(inode->i_mapping, pgoff); 2661out: 2662 *pagep = page; 2663 *ent = (swp_entry_t){ .val = 0 }; 2664} 2665#endif 2666 2667#define shmem_vm_ops generic_file_vm_ops 2668#define shmem_file_operations ramfs_file_operations 2669#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) 2670#define shmem_acct_size(flags, size) 0 2671#define shmem_unacct_size(flags, size) do {} while (0) 2672#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE 2673 2674#endif /* CONFIG_SHMEM */ 2675 2676/* common code */ 2677 2678/** 2679 * shmem_file_setup - get an unlinked file living in tmpfs 2680 * @name: name for dentry (to be seen in /proc/<pid>/maps 2681 * @size: size to be set for the file 2682 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size 2683 */ 2684struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) 2685{ 2686 int error; 2687 struct file *file; 2688 struct inode *inode; 2689 struct path path; 2690 struct dentry *root; 2691 struct qstr this; 2692 2693 if (IS_ERR(shm_mnt)) 2694 return (void *)shm_mnt; 2695 2696 if (size < 0 || size > SHMEM_MAX_BYTES) 2697 return ERR_PTR(-EINVAL); 2698 2699 if (shmem_acct_size(flags, size)) 2700 return ERR_PTR(-ENOMEM); 2701 2702 error = -ENOMEM; 2703 this.name = name; 2704 this.len = strlen(name); 2705 this.hash = 0; /* will go */ 2706 root = shm_mnt->mnt_root; 2707 path.dentry = d_alloc(root, &this); 2708 if (!path.dentry) 2709 goto put_memory; 2710 path.mnt = mntget(shm_mnt); 2711 2712 error = -ENOSPC; 2713 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); 2714 if (!inode) 2715 goto put_dentry; 2716 2717 d_instantiate(path.dentry, inode); 2718 inode->i_size = size; 2719 inode->i_nlink = 0; /* It is unlinked */ 2720#ifndef CONFIG_MMU 2721 error = ramfs_nommu_expand_for_mapping(inode, size); 2722 if (error) 2723 goto put_dentry; 2724#endif 2725 2726 error = -ENFILE; 2727 file = alloc_file(&path, FMODE_WRITE | FMODE_READ, 2728 &shmem_file_operations); 2729 if (!file) 2730 goto put_dentry; 2731 2732 return file; 2733 2734put_dentry: 2735 path_put(&path); 2736put_memory: 2737 shmem_unacct_size(flags, size); 2738 return ERR_PTR(error); 2739} 2740EXPORT_SYMBOL_GPL(shmem_file_setup); 2741 2742/** 2743 * shmem_zero_setup - setup a shared anonymous mapping 2744 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2745 */ 2746int shmem_zero_setup(struct vm_area_struct *vma) 2747{ 2748 struct file *file; 2749 loff_t size = vma->vm_end - vma->vm_start; 2750 2751 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2752 if (IS_ERR(file)) 2753 return PTR_ERR(file); 2754 2755 if (vma->vm_file) 2756 fput(vma->vm_file); 2757 vma->vm_file = file; 2758 vma->vm_ops = &shmem_vm_ops; 2759 return 0; 2760} 2761