shmem.c revision 1b061d9247f71cd15edc4c4c4600191a903642c0
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 vmtruncate or 731 * generic_delete_inode did it, before we lowered next_index. 732 * Also, though shmem_getpage checks i_size before adding to 733 * cache, no recheck after: so fix the narrow window there too. 734 * 735 * Recalling truncate_inode_pages_range and unmap_mapping_range 736 * every time for punch_hole (which never got a chance to clear 737 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 738 * yet hardly ever necessary: try to optimize them out later. 739 */ 740 truncate_inode_pages_range(inode->i_mapping, start, end); 741 if (punch_hole) 742 unmap_mapping_range(inode->i_mapping, start, 743 end - start, 1); 744 } 745 746 spin_lock(&info->lock); 747 info->flags &= ~SHMEM_TRUNCATE; 748 info->swapped -= nr_swaps_freed; 749 if (nr_pages_to_free) 750 shmem_free_blocks(inode, nr_pages_to_free); 751 shmem_recalc_inode(inode); 752 spin_unlock(&info->lock); 753 754 /* 755 * Empty swap vector directory pages to be freed? 756 */ 757 if (!list_empty(&pages_to_free)) { 758 pages_to_free.prev->next = NULL; 759 shmem_free_pages(pages_to_free.next); 760 } 761} 762 763static void shmem_truncate(struct inode *inode) 764{ 765 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 766} 767 768static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 769{ 770 struct inode *inode = dentry->d_inode; 771 struct page *page = NULL; 772 int error; 773 774 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 775 if (attr->ia_size < inode->i_size) { 776 /* 777 * If truncating down to a partial page, then 778 * if that page is already allocated, hold it 779 * in memory until the truncation is over, so 780 * truncate_partial_page cannnot miss it were 781 * it assigned to swap. 782 */ 783 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 784 (void) shmem_getpage(inode, 785 attr->ia_size>>PAGE_CACHE_SHIFT, 786 &page, SGP_READ, NULL); 787 if (page) 788 unlock_page(page); 789 } 790 /* 791 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 792 * detect if any pages might have been added to cache 793 * after truncate_inode_pages. But we needn't bother 794 * if it's being fully truncated to zero-length: the 795 * nrpages check is efficient enough in that case. 796 */ 797 if (attr->ia_size) { 798 struct shmem_inode_info *info = SHMEM_I(inode); 799 spin_lock(&info->lock); 800 info->flags &= ~SHMEM_PAGEIN; 801 spin_unlock(&info->lock); 802 } 803 } 804 } 805 806 error = inode_change_ok(inode, attr); 807 if (!error) 808 error = inode_setattr(inode, attr); 809#ifdef CONFIG_TMPFS_POSIX_ACL 810 if (!error && (attr->ia_valid & ATTR_MODE)) 811 error = generic_acl_chmod(inode); 812#endif 813 if (page) 814 page_cache_release(page); 815 return error; 816} 817 818static void shmem_delete_inode(struct inode *inode) 819{ 820 struct shmem_inode_info *info = SHMEM_I(inode); 821 822 if (inode->i_op->truncate == shmem_truncate) { 823 truncate_inode_pages(inode->i_mapping, 0); 824 shmem_unacct_size(info->flags, inode->i_size); 825 inode->i_size = 0; 826 shmem_truncate(inode); 827 if (!list_empty(&info->swaplist)) { 828 mutex_lock(&shmem_swaplist_mutex); 829 list_del_init(&info->swaplist); 830 mutex_unlock(&shmem_swaplist_mutex); 831 } 832 } 833 BUG_ON(inode->i_blocks); 834 shmem_free_inode(inode->i_sb); 835 clear_inode(inode); 836} 837 838static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 839{ 840 swp_entry_t *ptr; 841 842 for (ptr = dir; ptr < edir; ptr++) { 843 if (ptr->val == entry.val) 844 return ptr - dir; 845 } 846 return -1; 847} 848 849static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 850{ 851 struct inode *inode; 852 unsigned long idx; 853 unsigned long size; 854 unsigned long limit; 855 unsigned long stage; 856 struct page **dir; 857 struct page *subdir; 858 swp_entry_t *ptr; 859 int offset; 860 int error; 861 862 idx = 0; 863 ptr = info->i_direct; 864 spin_lock(&info->lock); 865 if (!info->swapped) { 866 list_del_init(&info->swaplist); 867 goto lost2; 868 } 869 limit = info->next_index; 870 size = limit; 871 if (size > SHMEM_NR_DIRECT) 872 size = SHMEM_NR_DIRECT; 873 offset = shmem_find_swp(entry, ptr, ptr+size); 874 if (offset >= 0) 875 goto found; 876 if (!info->i_indirect) 877 goto lost2; 878 879 dir = shmem_dir_map(info->i_indirect); 880 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 881 882 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 883 if (unlikely(idx == stage)) { 884 shmem_dir_unmap(dir-1); 885 if (cond_resched_lock(&info->lock)) { 886 /* check it has not been truncated */ 887 if (limit > info->next_index) { 888 limit = info->next_index; 889 if (idx >= limit) 890 goto lost2; 891 } 892 } 893 dir = shmem_dir_map(info->i_indirect) + 894 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 895 while (!*dir) { 896 dir++; 897 idx += ENTRIES_PER_PAGEPAGE; 898 if (idx >= limit) 899 goto lost1; 900 } 901 stage = idx + ENTRIES_PER_PAGEPAGE; 902 subdir = *dir; 903 shmem_dir_unmap(dir); 904 dir = shmem_dir_map(subdir); 905 } 906 subdir = *dir; 907 if (subdir && page_private(subdir)) { 908 ptr = shmem_swp_map(subdir); 909 size = limit - idx; 910 if (size > ENTRIES_PER_PAGE) 911 size = ENTRIES_PER_PAGE; 912 offset = shmem_find_swp(entry, ptr, ptr+size); 913 shmem_swp_unmap(ptr); 914 if (offset >= 0) { 915 shmem_dir_unmap(dir); 916 goto found; 917 } 918 } 919 } 920lost1: 921 shmem_dir_unmap(dir-1); 922lost2: 923 spin_unlock(&info->lock); 924 return 0; 925found: 926 idx += offset; 927 inode = igrab(&info->vfs_inode); 928 spin_unlock(&info->lock); 929 930 /* 931 * Move _head_ to start search for next from here. 932 * But be careful: shmem_delete_inode checks list_empty without taking 933 * mutex, and there's an instant in list_move_tail when info->swaplist 934 * would appear empty, if it were the only one on shmem_swaplist. We 935 * could avoid doing it if inode NULL; or use this minor optimization. 936 */ 937 if (shmem_swaplist.next != &info->swaplist) 938 list_move_tail(&shmem_swaplist, &info->swaplist); 939 mutex_unlock(&shmem_swaplist_mutex); 940 941 error = 1; 942 if (!inode) 943 goto out; 944 /* 945 * Charge page using GFP_KERNEL while we can wait. 946 * Charged back to the user(not to caller) when swap account is used. 947 * add_to_page_cache() will be called with GFP_NOWAIT. 948 */ 949 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); 950 if (error) 951 goto out; 952 error = radix_tree_preload(GFP_KERNEL); 953 if (error) { 954 mem_cgroup_uncharge_cache_page(page); 955 goto out; 956 } 957 error = 1; 958 959 spin_lock(&info->lock); 960 ptr = shmem_swp_entry(info, idx, NULL); 961 if (ptr && ptr->val == entry.val) { 962 error = add_to_page_cache_locked(page, inode->i_mapping, 963 idx, GFP_NOWAIT); 964 /* does mem_cgroup_uncharge_cache_page on error */ 965 } else /* we must compensate for our precharge above */ 966 mem_cgroup_uncharge_cache_page(page); 967 968 if (error == -EEXIST) { 969 struct page *filepage = find_get_page(inode->i_mapping, idx); 970 error = 1; 971 if (filepage) { 972 /* 973 * There might be a more uptodate page coming down 974 * from a stacked writepage: forget our swappage if so. 975 */ 976 if (PageUptodate(filepage)) 977 error = 0; 978 page_cache_release(filepage); 979 } 980 } 981 if (!error) { 982 delete_from_swap_cache(page); 983 set_page_dirty(page); 984 info->flags |= SHMEM_PAGEIN; 985 shmem_swp_set(info, ptr, 0); 986 swap_free(entry); 987 error = 1; /* not an error, but entry was found */ 988 } 989 if (ptr) 990 shmem_swp_unmap(ptr); 991 spin_unlock(&info->lock); 992 radix_tree_preload_end(); 993out: 994 unlock_page(page); 995 page_cache_release(page); 996 iput(inode); /* allows for NULL */ 997 return error; 998} 999 1000/* 1001 * shmem_unuse() search for an eventually swapped out shmem page. 1002 */ 1003int shmem_unuse(swp_entry_t entry, struct page *page) 1004{ 1005 struct list_head *p, *next; 1006 struct shmem_inode_info *info; 1007 int found = 0; 1008 1009 mutex_lock(&shmem_swaplist_mutex); 1010 list_for_each_safe(p, next, &shmem_swaplist) { 1011 info = list_entry(p, struct shmem_inode_info, swaplist); 1012 found = shmem_unuse_inode(info, entry, page); 1013 cond_resched(); 1014 if (found) 1015 goto out; 1016 } 1017 mutex_unlock(&shmem_swaplist_mutex); 1018 /* 1019 * Can some race bring us here? We've been holding page lock, 1020 * so I think not; but would rather try again later than BUG() 1021 */ 1022 unlock_page(page); 1023 page_cache_release(page); 1024out: 1025 return (found < 0) ? found : 0; 1026} 1027 1028/* 1029 * Move the page from the page cache to the swap cache. 1030 */ 1031static int shmem_writepage(struct page *page, struct writeback_control *wbc) 1032{ 1033 struct shmem_inode_info *info; 1034 swp_entry_t *entry, swap; 1035 struct address_space *mapping; 1036 unsigned long index; 1037 struct inode *inode; 1038 1039 BUG_ON(!PageLocked(page)); 1040 mapping = page->mapping; 1041 index = page->index; 1042 inode = mapping->host; 1043 info = SHMEM_I(inode); 1044 if (info->flags & VM_LOCKED) 1045 goto redirty; 1046 if (!total_swap_pages) 1047 goto redirty; 1048 1049 /* 1050 * shmem_backing_dev_info's capabilities prevent regular writeback or 1051 * sync from ever calling shmem_writepage; but a stacking filesystem 1052 * may use the ->writepage of its underlying filesystem, in which case 1053 * tmpfs should write out to swap only in response to memory pressure, 1054 * and not for the writeback threads or sync. However, in those cases, 1055 * we do still want to check if there's a redundant swappage to be 1056 * discarded. 1057 */ 1058 if (wbc->for_reclaim) 1059 swap = get_swap_page(); 1060 else 1061 swap.val = 0; 1062 1063 spin_lock(&info->lock); 1064 if (index >= info->next_index) { 1065 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1066 goto unlock; 1067 } 1068 entry = shmem_swp_entry(info, index, NULL); 1069 if (entry->val) { 1070 /* 1071 * The more uptodate page coming down from a stacked 1072 * writepage should replace our old swappage. 1073 */ 1074 free_swap_and_cache(*entry); 1075 shmem_swp_set(info, entry, 0); 1076 } 1077 shmem_recalc_inode(inode); 1078 1079 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1080 remove_from_page_cache(page); 1081 shmem_swp_set(info, entry, swap.val); 1082 shmem_swp_unmap(entry); 1083 if (list_empty(&info->swaplist)) 1084 inode = igrab(inode); 1085 else 1086 inode = NULL; 1087 spin_unlock(&info->lock); 1088 swap_shmem_alloc(swap); 1089 BUG_ON(page_mapped(page)); 1090 page_cache_release(page); /* pagecache ref */ 1091 swap_writepage(page, wbc); 1092 if (inode) { 1093 mutex_lock(&shmem_swaplist_mutex); 1094 /* move instead of add in case we're racing */ 1095 list_move_tail(&info->swaplist, &shmem_swaplist); 1096 mutex_unlock(&shmem_swaplist_mutex); 1097 iput(inode); 1098 } 1099 return 0; 1100 } 1101 1102 shmem_swp_unmap(entry); 1103unlock: 1104 spin_unlock(&info->lock); 1105 /* 1106 * add_to_swap_cache() doesn't return -EEXIST, so we can safely 1107 * clear SWAP_HAS_CACHE flag. 1108 */ 1109 swapcache_free(swap, NULL); 1110redirty: 1111 set_page_dirty(page); 1112 if (wbc->for_reclaim) 1113 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1114 unlock_page(page); 1115 return 0; 1116} 1117 1118#ifdef CONFIG_NUMA 1119#ifdef CONFIG_TMPFS 1120static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) 1121{ 1122 char buffer[64]; 1123 1124 if (!mpol || mpol->mode == MPOL_DEFAULT) 1125 return; /* show nothing */ 1126 1127 mpol_to_str(buffer, sizeof(buffer), mpol, 1); 1128 1129 seq_printf(seq, ",mpol=%s", buffer); 1130} 1131 1132static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1133{ 1134 struct mempolicy *mpol = NULL; 1135 if (sbinfo->mpol) { 1136 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ 1137 mpol = sbinfo->mpol; 1138 mpol_get(mpol); 1139 spin_unlock(&sbinfo->stat_lock); 1140 } 1141 return mpol; 1142} 1143#endif /* CONFIG_TMPFS */ 1144 1145static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1146 struct shmem_inode_info *info, unsigned long idx) 1147{ 1148 struct mempolicy mpol, *spol; 1149 struct vm_area_struct pvma; 1150 struct page *page; 1151 1152 spol = mpol_cond_copy(&mpol, 1153 mpol_shared_policy_lookup(&info->policy, idx)); 1154 1155 /* Create a pseudo vma that just contains the policy */ 1156 pvma.vm_start = 0; 1157 pvma.vm_pgoff = idx; 1158 pvma.vm_ops = NULL; 1159 pvma.vm_policy = spol; 1160 page = swapin_readahead(entry, gfp, &pvma, 0); 1161 return page; 1162} 1163 1164static struct page *shmem_alloc_page(gfp_t gfp, 1165 struct shmem_inode_info *info, unsigned long idx) 1166{ 1167 struct vm_area_struct pvma; 1168 1169 /* Create a pseudo vma that just contains the policy */ 1170 pvma.vm_start = 0; 1171 pvma.vm_pgoff = idx; 1172 pvma.vm_ops = NULL; 1173 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1174 1175 /* 1176 * alloc_page_vma() will drop the shared policy reference 1177 */ 1178 return alloc_page_vma(gfp, &pvma, 0); 1179} 1180#else /* !CONFIG_NUMA */ 1181#ifdef CONFIG_TMPFS 1182static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) 1183{ 1184} 1185#endif /* CONFIG_TMPFS */ 1186 1187static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1188 struct shmem_inode_info *info, unsigned long idx) 1189{ 1190 return swapin_readahead(entry, gfp, NULL, 0); 1191} 1192 1193static inline struct page *shmem_alloc_page(gfp_t gfp, 1194 struct shmem_inode_info *info, unsigned long idx) 1195{ 1196 return alloc_page(gfp); 1197} 1198#endif /* CONFIG_NUMA */ 1199 1200#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) 1201static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1202{ 1203 return NULL; 1204} 1205#endif 1206 1207/* 1208 * shmem_getpage - either get the page from swap or allocate a new one 1209 * 1210 * If we allocate a new one we do not mark it dirty. That's up to the 1211 * vm. If we swap it in we mark it dirty since we also free the swap 1212 * entry since a page cannot live in both the swap and page cache 1213 */ 1214static int shmem_getpage(struct inode *inode, unsigned long idx, 1215 struct page **pagep, enum sgp_type sgp, int *type) 1216{ 1217 struct address_space *mapping = inode->i_mapping; 1218 struct shmem_inode_info *info = SHMEM_I(inode); 1219 struct shmem_sb_info *sbinfo; 1220 struct page *filepage = *pagep; 1221 struct page *swappage; 1222 swp_entry_t *entry; 1223 swp_entry_t swap; 1224 gfp_t gfp; 1225 int error; 1226 1227 if (idx >= SHMEM_MAX_INDEX) 1228 return -EFBIG; 1229 1230 if (type) 1231 *type = 0; 1232 1233 /* 1234 * Normally, filepage is NULL on entry, and either found 1235 * uptodate immediately, or allocated and zeroed, or read 1236 * in under swappage, which is then assigned to filepage. 1237 * But shmem_readpage (required for splice) passes in a locked 1238 * filepage, which may be found not uptodate by other callers 1239 * too, and may need to be copied from the swappage read in. 1240 */ 1241repeat: 1242 if (!filepage) 1243 filepage = find_lock_page(mapping, idx); 1244 if (filepage && PageUptodate(filepage)) 1245 goto done; 1246 error = 0; 1247 gfp = mapping_gfp_mask(mapping); 1248 if (!filepage) { 1249 /* 1250 * Try to preload while we can wait, to not make a habit of 1251 * draining atomic reserves; but don't latch on to this cpu. 1252 */ 1253 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1254 if (error) 1255 goto failed; 1256 radix_tree_preload_end(); 1257 } 1258 1259 spin_lock(&info->lock); 1260 shmem_recalc_inode(inode); 1261 entry = shmem_swp_alloc(info, idx, sgp); 1262 if (IS_ERR(entry)) { 1263 spin_unlock(&info->lock); 1264 error = PTR_ERR(entry); 1265 goto failed; 1266 } 1267 swap = *entry; 1268 1269 if (swap.val) { 1270 /* Look it up and read it in.. */ 1271 swappage = lookup_swap_cache(swap); 1272 if (!swappage) { 1273 shmem_swp_unmap(entry); 1274 /* here we actually do the io */ 1275 if (type && !(*type & VM_FAULT_MAJOR)) { 1276 __count_vm_event(PGMAJFAULT); 1277 *type |= VM_FAULT_MAJOR; 1278 } 1279 spin_unlock(&info->lock); 1280 swappage = shmem_swapin(swap, gfp, info, idx); 1281 if (!swappage) { 1282 spin_lock(&info->lock); 1283 entry = shmem_swp_alloc(info, idx, sgp); 1284 if (IS_ERR(entry)) 1285 error = PTR_ERR(entry); 1286 else { 1287 if (entry->val == swap.val) 1288 error = -ENOMEM; 1289 shmem_swp_unmap(entry); 1290 } 1291 spin_unlock(&info->lock); 1292 if (error) 1293 goto failed; 1294 goto repeat; 1295 } 1296 wait_on_page_locked(swappage); 1297 page_cache_release(swappage); 1298 goto repeat; 1299 } 1300 1301 /* We have to do this with page locked to prevent races */ 1302 if (!trylock_page(swappage)) { 1303 shmem_swp_unmap(entry); 1304 spin_unlock(&info->lock); 1305 wait_on_page_locked(swappage); 1306 page_cache_release(swappage); 1307 goto repeat; 1308 } 1309 if (PageWriteback(swappage)) { 1310 shmem_swp_unmap(entry); 1311 spin_unlock(&info->lock); 1312 wait_on_page_writeback(swappage); 1313 unlock_page(swappage); 1314 page_cache_release(swappage); 1315 goto repeat; 1316 } 1317 if (!PageUptodate(swappage)) { 1318 shmem_swp_unmap(entry); 1319 spin_unlock(&info->lock); 1320 unlock_page(swappage); 1321 page_cache_release(swappage); 1322 error = -EIO; 1323 goto failed; 1324 } 1325 1326 if (filepage) { 1327 shmem_swp_set(info, entry, 0); 1328 shmem_swp_unmap(entry); 1329 delete_from_swap_cache(swappage); 1330 spin_unlock(&info->lock); 1331 copy_highpage(filepage, swappage); 1332 unlock_page(swappage); 1333 page_cache_release(swappage); 1334 flush_dcache_page(filepage); 1335 SetPageUptodate(filepage); 1336 set_page_dirty(filepage); 1337 swap_free(swap); 1338 } else if (!(error = add_to_page_cache_locked(swappage, mapping, 1339 idx, GFP_NOWAIT))) { 1340 info->flags |= SHMEM_PAGEIN; 1341 shmem_swp_set(info, entry, 0); 1342 shmem_swp_unmap(entry); 1343 delete_from_swap_cache(swappage); 1344 spin_unlock(&info->lock); 1345 filepage = swappage; 1346 set_page_dirty(filepage); 1347 swap_free(swap); 1348 } else { 1349 shmem_swp_unmap(entry); 1350 spin_unlock(&info->lock); 1351 if (error == -ENOMEM) { 1352 /* 1353 * reclaim from proper memory cgroup and 1354 * call memcg's OOM if needed. 1355 */ 1356 error = mem_cgroup_shmem_charge_fallback( 1357 swappage, 1358 current->mm, 1359 gfp); 1360 if (error) { 1361 unlock_page(swappage); 1362 page_cache_release(swappage); 1363 goto failed; 1364 } 1365 } 1366 unlock_page(swappage); 1367 page_cache_release(swappage); 1368 goto repeat; 1369 } 1370 } else if (sgp == SGP_READ && !filepage) { 1371 shmem_swp_unmap(entry); 1372 filepage = find_get_page(mapping, idx); 1373 if (filepage && 1374 (!PageUptodate(filepage) || !trylock_page(filepage))) { 1375 spin_unlock(&info->lock); 1376 wait_on_page_locked(filepage); 1377 page_cache_release(filepage); 1378 filepage = NULL; 1379 goto repeat; 1380 } 1381 spin_unlock(&info->lock); 1382 } else { 1383 shmem_swp_unmap(entry); 1384 sbinfo = SHMEM_SB(inode->i_sb); 1385 if (sbinfo->max_blocks) { 1386 spin_lock(&sbinfo->stat_lock); 1387 if (sbinfo->free_blocks == 0 || 1388 shmem_acct_block(info->flags)) { 1389 spin_unlock(&sbinfo->stat_lock); 1390 spin_unlock(&info->lock); 1391 error = -ENOSPC; 1392 goto failed; 1393 } 1394 sbinfo->free_blocks--; 1395 inode->i_blocks += BLOCKS_PER_PAGE; 1396 spin_unlock(&sbinfo->stat_lock); 1397 } else if (shmem_acct_block(info->flags)) { 1398 spin_unlock(&info->lock); 1399 error = -ENOSPC; 1400 goto failed; 1401 } 1402 1403 if (!filepage) { 1404 int ret; 1405 1406 spin_unlock(&info->lock); 1407 filepage = shmem_alloc_page(gfp, info, idx); 1408 if (!filepage) { 1409 shmem_unacct_blocks(info->flags, 1); 1410 shmem_free_blocks(inode, 1); 1411 error = -ENOMEM; 1412 goto failed; 1413 } 1414 SetPageSwapBacked(filepage); 1415 1416 /* Precharge page while we can wait, compensate after */ 1417 error = mem_cgroup_cache_charge(filepage, current->mm, 1418 GFP_KERNEL); 1419 if (error) { 1420 page_cache_release(filepage); 1421 shmem_unacct_blocks(info->flags, 1); 1422 shmem_free_blocks(inode, 1); 1423 filepage = NULL; 1424 goto failed; 1425 } 1426 1427 spin_lock(&info->lock); 1428 entry = shmem_swp_alloc(info, idx, sgp); 1429 if (IS_ERR(entry)) 1430 error = PTR_ERR(entry); 1431 else { 1432 swap = *entry; 1433 shmem_swp_unmap(entry); 1434 } 1435 ret = error || swap.val; 1436 if (ret) 1437 mem_cgroup_uncharge_cache_page(filepage); 1438 else 1439 ret = add_to_page_cache_lru(filepage, mapping, 1440 idx, GFP_NOWAIT); 1441 /* 1442 * At add_to_page_cache_lru() failure, uncharge will 1443 * be done automatically. 1444 */ 1445 if (ret) { 1446 spin_unlock(&info->lock); 1447 page_cache_release(filepage); 1448 shmem_unacct_blocks(info->flags, 1); 1449 shmem_free_blocks(inode, 1); 1450 filepage = NULL; 1451 if (error) 1452 goto failed; 1453 goto repeat; 1454 } 1455 info->flags |= SHMEM_PAGEIN; 1456 } 1457 1458 info->alloced++; 1459 spin_unlock(&info->lock); 1460 clear_highpage(filepage); 1461 flush_dcache_page(filepage); 1462 SetPageUptodate(filepage); 1463 if (sgp == SGP_DIRTY) 1464 set_page_dirty(filepage); 1465 } 1466done: 1467 *pagep = filepage; 1468 return 0; 1469 1470failed: 1471 if (*pagep != filepage) { 1472 unlock_page(filepage); 1473 page_cache_release(filepage); 1474 } 1475 return error; 1476} 1477 1478static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1479{ 1480 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1481 int error; 1482 int ret; 1483 1484 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1485 return VM_FAULT_SIGBUS; 1486 1487 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1488 if (error) 1489 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1490 1491 return ret | VM_FAULT_LOCKED; 1492} 1493 1494#ifdef CONFIG_NUMA 1495static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1496{ 1497 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1498 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1499} 1500 1501static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1502 unsigned long addr) 1503{ 1504 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1505 unsigned long idx; 1506 1507 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1508 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1509} 1510#endif 1511 1512int shmem_lock(struct file *file, int lock, struct user_struct *user) 1513{ 1514 struct inode *inode = file->f_path.dentry->d_inode; 1515 struct shmem_inode_info *info = SHMEM_I(inode); 1516 int retval = -ENOMEM; 1517 1518 spin_lock(&info->lock); 1519 if (lock && !(info->flags & VM_LOCKED)) { 1520 if (!user_shm_lock(inode->i_size, user)) 1521 goto out_nomem; 1522 info->flags |= VM_LOCKED; 1523 mapping_set_unevictable(file->f_mapping); 1524 } 1525 if (!lock && (info->flags & VM_LOCKED) && user) { 1526 user_shm_unlock(inode->i_size, user); 1527 info->flags &= ~VM_LOCKED; 1528 mapping_clear_unevictable(file->f_mapping); 1529 scan_mapping_unevictable_pages(file->f_mapping); 1530 } 1531 retval = 0; 1532 1533out_nomem: 1534 spin_unlock(&info->lock); 1535 return retval; 1536} 1537 1538static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1539{ 1540 file_accessed(file); 1541 vma->vm_ops = &shmem_vm_ops; 1542 vma->vm_flags |= VM_CAN_NONLINEAR; 1543 return 0; 1544} 1545 1546static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, 1547 int mode, dev_t dev, unsigned long flags) 1548{ 1549 struct inode *inode; 1550 struct shmem_inode_info *info; 1551 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1552 1553 if (shmem_reserve_inode(sb)) 1554 return NULL; 1555 1556 inode = new_inode(sb); 1557 if (inode) { 1558 inode_init_owner(inode, dir, mode); 1559 inode->i_blocks = 0; 1560 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1561 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1562 inode->i_generation = get_seconds(); 1563 info = SHMEM_I(inode); 1564 memset(info, 0, (char *)inode - (char *)info); 1565 spin_lock_init(&info->lock); 1566 info->flags = flags & VM_NORESERVE; 1567 INIT_LIST_HEAD(&info->swaplist); 1568 cache_no_acl(inode); 1569 1570 switch (mode & S_IFMT) { 1571 default: 1572 inode->i_op = &shmem_special_inode_operations; 1573 init_special_inode(inode, mode, dev); 1574 break; 1575 case S_IFREG: 1576 inode->i_mapping->a_ops = &shmem_aops; 1577 inode->i_op = &shmem_inode_operations; 1578 inode->i_fop = &shmem_file_operations; 1579 mpol_shared_policy_init(&info->policy, 1580 shmem_get_sbmpol(sbinfo)); 1581 break; 1582 case S_IFDIR: 1583 inc_nlink(inode); 1584 /* Some things misbehave if size == 0 on a directory */ 1585 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1586 inode->i_op = &shmem_dir_inode_operations; 1587 inode->i_fop = &simple_dir_operations; 1588 break; 1589 case S_IFLNK: 1590 /* 1591 * Must not load anything in the rbtree, 1592 * mpol_free_shared_policy will not be called. 1593 */ 1594 mpol_shared_policy_init(&info->policy, NULL); 1595 break; 1596 } 1597 } else 1598 shmem_free_inode(sb); 1599 return inode; 1600} 1601 1602#ifdef CONFIG_TMPFS 1603static const struct inode_operations shmem_symlink_inode_operations; 1604static const struct inode_operations shmem_symlink_inline_operations; 1605 1606/* 1607 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1608 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1609 * below the loop driver, in the generic fashion that many filesystems support. 1610 */ 1611static int shmem_readpage(struct file *file, struct page *page) 1612{ 1613 struct inode *inode = page->mapping->host; 1614 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1615 unlock_page(page); 1616 return error; 1617} 1618 1619static int 1620shmem_write_begin(struct file *file, struct address_space *mapping, 1621 loff_t pos, unsigned len, unsigned flags, 1622 struct page **pagep, void **fsdata) 1623{ 1624 struct inode *inode = mapping->host; 1625 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1626 *pagep = NULL; 1627 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1628} 1629 1630static int 1631shmem_write_end(struct file *file, struct address_space *mapping, 1632 loff_t pos, unsigned len, unsigned copied, 1633 struct page *page, void *fsdata) 1634{ 1635 struct inode *inode = mapping->host; 1636 1637 if (pos + copied > inode->i_size) 1638 i_size_write(inode, pos + copied); 1639 1640 set_page_dirty(page); 1641 unlock_page(page); 1642 page_cache_release(page); 1643 1644 return copied; 1645} 1646 1647static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1648{ 1649 struct inode *inode = filp->f_path.dentry->d_inode; 1650 struct address_space *mapping = inode->i_mapping; 1651 unsigned long index, offset; 1652 enum sgp_type sgp = SGP_READ; 1653 1654 /* 1655 * Might this read be for a stacking filesystem? Then when reading 1656 * holes of a sparse file, we actually need to allocate those pages, 1657 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1658 */ 1659 if (segment_eq(get_fs(), KERNEL_DS)) 1660 sgp = SGP_DIRTY; 1661 1662 index = *ppos >> PAGE_CACHE_SHIFT; 1663 offset = *ppos & ~PAGE_CACHE_MASK; 1664 1665 for (;;) { 1666 struct page *page = NULL; 1667 unsigned long end_index, nr, ret; 1668 loff_t i_size = i_size_read(inode); 1669 1670 end_index = i_size >> PAGE_CACHE_SHIFT; 1671 if (index > end_index) 1672 break; 1673 if (index == end_index) { 1674 nr = i_size & ~PAGE_CACHE_MASK; 1675 if (nr <= offset) 1676 break; 1677 } 1678 1679 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1680 if (desc->error) { 1681 if (desc->error == -EINVAL) 1682 desc->error = 0; 1683 break; 1684 } 1685 if (page) 1686 unlock_page(page); 1687 1688 /* 1689 * We must evaluate after, since reads (unlike writes) 1690 * are called without i_mutex protection against truncate 1691 */ 1692 nr = PAGE_CACHE_SIZE; 1693 i_size = i_size_read(inode); 1694 end_index = i_size >> PAGE_CACHE_SHIFT; 1695 if (index == end_index) { 1696 nr = i_size & ~PAGE_CACHE_MASK; 1697 if (nr <= offset) { 1698 if (page) 1699 page_cache_release(page); 1700 break; 1701 } 1702 } 1703 nr -= offset; 1704 1705 if (page) { 1706 /* 1707 * If users can be writing to this page using arbitrary 1708 * virtual addresses, take care about potential aliasing 1709 * before reading the page on the kernel side. 1710 */ 1711 if (mapping_writably_mapped(mapping)) 1712 flush_dcache_page(page); 1713 /* 1714 * Mark the page accessed if we read the beginning. 1715 */ 1716 if (!offset) 1717 mark_page_accessed(page); 1718 } else { 1719 page = ZERO_PAGE(0); 1720 page_cache_get(page); 1721 } 1722 1723 /* 1724 * Ok, we have the page, and it's up-to-date, so 1725 * now we can copy it to user space... 1726 * 1727 * The actor routine returns how many bytes were actually used.. 1728 * NOTE! This may not be the same as how much of a user buffer 1729 * we filled up (we may be padding etc), so we can only update 1730 * "pos" here (the actor routine has to update the user buffer 1731 * pointers and the remaining count). 1732 */ 1733 ret = actor(desc, page, offset, nr); 1734 offset += ret; 1735 index += offset >> PAGE_CACHE_SHIFT; 1736 offset &= ~PAGE_CACHE_MASK; 1737 1738 page_cache_release(page); 1739 if (ret != nr || !desc->count) 1740 break; 1741 1742 cond_resched(); 1743 } 1744 1745 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1746 file_accessed(filp); 1747} 1748 1749static ssize_t shmem_file_aio_read(struct kiocb *iocb, 1750 const struct iovec *iov, unsigned long nr_segs, loff_t pos) 1751{ 1752 struct file *filp = iocb->ki_filp; 1753 ssize_t retval; 1754 unsigned long seg; 1755 size_t count; 1756 loff_t *ppos = &iocb->ki_pos; 1757 1758 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); 1759 if (retval) 1760 return retval; 1761 1762 for (seg = 0; seg < nr_segs; seg++) { 1763 read_descriptor_t desc; 1764 1765 desc.written = 0; 1766 desc.arg.buf = iov[seg].iov_base; 1767 desc.count = iov[seg].iov_len; 1768 if (desc.count == 0) 1769 continue; 1770 desc.error = 0; 1771 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1772 retval += desc.written; 1773 if (desc.error) { 1774 retval = retval ?: desc.error; 1775 break; 1776 } 1777 if (desc.count > 0) 1778 break; 1779 } 1780 return retval; 1781} 1782 1783static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1784{ 1785 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1786 1787 buf->f_type = TMPFS_MAGIC; 1788 buf->f_bsize = PAGE_CACHE_SIZE; 1789 buf->f_namelen = NAME_MAX; 1790 spin_lock(&sbinfo->stat_lock); 1791 if (sbinfo->max_blocks) { 1792 buf->f_blocks = sbinfo->max_blocks; 1793 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1794 } 1795 if (sbinfo->max_inodes) { 1796 buf->f_files = sbinfo->max_inodes; 1797 buf->f_ffree = sbinfo->free_inodes; 1798 } 1799 /* else leave those fields 0 like simple_statfs */ 1800 spin_unlock(&sbinfo->stat_lock); 1801 return 0; 1802} 1803 1804/* 1805 * File creation. Allocate an inode, and we're done.. 1806 */ 1807static int 1808shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1809{ 1810 struct inode *inode; 1811 int error = -ENOSPC; 1812 1813 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); 1814 if (inode) { 1815 error = security_inode_init_security(inode, dir, NULL, NULL, 1816 NULL); 1817 if (error) { 1818 if (error != -EOPNOTSUPP) { 1819 iput(inode); 1820 return error; 1821 } 1822 } 1823#ifdef CONFIG_TMPFS_POSIX_ACL 1824 error = generic_acl_init(inode, dir); 1825 if (error) { 1826 iput(inode); 1827 return error; 1828 } 1829#else 1830 error = 0; 1831#endif 1832 dir->i_size += BOGO_DIRENT_SIZE; 1833 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1834 d_instantiate(dentry, inode); 1835 dget(dentry); /* Extra count - pin the dentry in core */ 1836 } 1837 return error; 1838} 1839 1840static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1841{ 1842 int error; 1843 1844 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1845 return error; 1846 inc_nlink(dir); 1847 return 0; 1848} 1849 1850static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1851 struct nameidata *nd) 1852{ 1853 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1854} 1855 1856/* 1857 * Link a file.. 1858 */ 1859static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1860{ 1861 struct inode *inode = old_dentry->d_inode; 1862 int ret; 1863 1864 /* 1865 * No ordinary (disk based) filesystem counts links as inodes; 1866 * but each new link needs a new dentry, pinning lowmem, and 1867 * tmpfs dentries cannot be pruned until they are unlinked. 1868 */ 1869 ret = shmem_reserve_inode(inode->i_sb); 1870 if (ret) 1871 goto out; 1872 1873 dir->i_size += BOGO_DIRENT_SIZE; 1874 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1875 inc_nlink(inode); 1876 atomic_inc(&inode->i_count); /* New dentry reference */ 1877 dget(dentry); /* Extra pinning count for the created dentry */ 1878 d_instantiate(dentry, inode); 1879out: 1880 return ret; 1881} 1882 1883static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1884{ 1885 struct inode *inode = dentry->d_inode; 1886 1887 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1888 shmem_free_inode(inode->i_sb); 1889 1890 dir->i_size -= BOGO_DIRENT_SIZE; 1891 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1892 drop_nlink(inode); 1893 dput(dentry); /* Undo the count from "create" - this does all the work */ 1894 return 0; 1895} 1896 1897static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1898{ 1899 if (!simple_empty(dentry)) 1900 return -ENOTEMPTY; 1901 1902 drop_nlink(dentry->d_inode); 1903 drop_nlink(dir); 1904 return shmem_unlink(dir, dentry); 1905} 1906 1907/* 1908 * The VFS layer already does all the dentry stuff for rename, 1909 * we just have to decrement the usage count for the target if 1910 * it exists so that the VFS layer correctly free's it when it 1911 * gets overwritten. 1912 */ 1913static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1914{ 1915 struct inode *inode = old_dentry->d_inode; 1916 int they_are_dirs = S_ISDIR(inode->i_mode); 1917 1918 if (!simple_empty(new_dentry)) 1919 return -ENOTEMPTY; 1920 1921 if (new_dentry->d_inode) { 1922 (void) shmem_unlink(new_dir, new_dentry); 1923 if (they_are_dirs) 1924 drop_nlink(old_dir); 1925 } else if (they_are_dirs) { 1926 drop_nlink(old_dir); 1927 inc_nlink(new_dir); 1928 } 1929 1930 old_dir->i_size -= BOGO_DIRENT_SIZE; 1931 new_dir->i_size += BOGO_DIRENT_SIZE; 1932 old_dir->i_ctime = old_dir->i_mtime = 1933 new_dir->i_ctime = new_dir->i_mtime = 1934 inode->i_ctime = CURRENT_TIME; 1935 return 0; 1936} 1937 1938static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1939{ 1940 int error; 1941 int len; 1942 struct inode *inode; 1943 struct page *page = NULL; 1944 char *kaddr; 1945 struct shmem_inode_info *info; 1946 1947 len = strlen(symname) + 1; 1948 if (len > PAGE_CACHE_SIZE) 1949 return -ENAMETOOLONG; 1950 1951 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); 1952 if (!inode) 1953 return -ENOSPC; 1954 1955 error = security_inode_init_security(inode, dir, NULL, NULL, 1956 NULL); 1957 if (error) { 1958 if (error != -EOPNOTSUPP) { 1959 iput(inode); 1960 return error; 1961 } 1962 error = 0; 1963 } 1964 1965 info = SHMEM_I(inode); 1966 inode->i_size = len-1; 1967 if (len <= (char *)inode - (char *)info) { 1968 /* do it inline */ 1969 memcpy(info, symname, len); 1970 inode->i_op = &shmem_symlink_inline_operations; 1971 } else { 1972 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1973 if (error) { 1974 iput(inode); 1975 return error; 1976 } 1977 inode->i_mapping->a_ops = &shmem_aops; 1978 inode->i_op = &shmem_symlink_inode_operations; 1979 kaddr = kmap_atomic(page, KM_USER0); 1980 memcpy(kaddr, symname, len); 1981 kunmap_atomic(kaddr, KM_USER0); 1982 set_page_dirty(page); 1983 unlock_page(page); 1984 page_cache_release(page); 1985 } 1986 dir->i_size += BOGO_DIRENT_SIZE; 1987 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1988 d_instantiate(dentry, inode); 1989 dget(dentry); 1990 return 0; 1991} 1992 1993static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1994{ 1995 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1996 return NULL; 1997} 1998 1999static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 2000{ 2001 struct page *page = NULL; 2002 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 2003 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 2004 if (page) 2005 unlock_page(page); 2006 return page; 2007} 2008 2009static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 2010{ 2011 if (!IS_ERR(nd_get_link(nd))) { 2012 struct page *page = cookie; 2013 kunmap(page); 2014 mark_page_accessed(page); 2015 page_cache_release(page); 2016 } 2017} 2018 2019static const struct inode_operations shmem_symlink_inline_operations = { 2020 .readlink = generic_readlink, 2021 .follow_link = shmem_follow_link_inline, 2022}; 2023 2024static const struct inode_operations shmem_symlink_inode_operations = { 2025 .truncate = shmem_truncate, 2026 .readlink = generic_readlink, 2027 .follow_link = shmem_follow_link, 2028 .put_link = shmem_put_link, 2029}; 2030 2031#ifdef CONFIG_TMPFS_POSIX_ACL 2032/* 2033 * Superblocks without xattr inode operations will get security.* xattr 2034 * support from the VFS "for free". As soon as we have any other xattrs 2035 * like ACLs, we also need to implement the security.* handlers at 2036 * filesystem level, though. 2037 */ 2038 2039static size_t shmem_xattr_security_list(struct dentry *dentry, char *list, 2040 size_t list_len, const char *name, 2041 size_t name_len, int handler_flags) 2042{ 2043 return security_inode_listsecurity(dentry->d_inode, list, list_len); 2044} 2045 2046static int shmem_xattr_security_get(struct dentry *dentry, const char *name, 2047 void *buffer, size_t size, int handler_flags) 2048{ 2049 if (strcmp(name, "") == 0) 2050 return -EINVAL; 2051 return xattr_getsecurity(dentry->d_inode, name, buffer, size); 2052} 2053 2054static int shmem_xattr_security_set(struct dentry *dentry, const char *name, 2055 const void *value, size_t size, int flags, int handler_flags) 2056{ 2057 if (strcmp(name, "") == 0) 2058 return -EINVAL; 2059 return security_inode_setsecurity(dentry->d_inode, name, value, 2060 size, flags); 2061} 2062 2063static const struct xattr_handler shmem_xattr_security_handler = { 2064 .prefix = XATTR_SECURITY_PREFIX, 2065 .list = shmem_xattr_security_list, 2066 .get = shmem_xattr_security_get, 2067 .set = shmem_xattr_security_set, 2068}; 2069 2070static const struct xattr_handler *shmem_xattr_handlers[] = { 2071 &generic_acl_access_handler, 2072 &generic_acl_default_handler, 2073 &shmem_xattr_security_handler, 2074 NULL 2075}; 2076#endif 2077 2078static struct dentry *shmem_get_parent(struct dentry *child) 2079{ 2080 return ERR_PTR(-ESTALE); 2081} 2082 2083static int shmem_match(struct inode *ino, void *vfh) 2084{ 2085 __u32 *fh = vfh; 2086 __u64 inum = fh[2]; 2087 inum = (inum << 32) | fh[1]; 2088 return ino->i_ino == inum && fh[0] == ino->i_generation; 2089} 2090 2091static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2092 struct fid *fid, int fh_len, int fh_type) 2093{ 2094 struct inode *inode; 2095 struct dentry *dentry = NULL; 2096 u64 inum = fid->raw[2]; 2097 inum = (inum << 32) | fid->raw[1]; 2098 2099 if (fh_len < 3) 2100 return NULL; 2101 2102 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2103 shmem_match, fid->raw); 2104 if (inode) { 2105 dentry = d_find_alias(inode); 2106 iput(inode); 2107 } 2108 2109 return dentry; 2110} 2111 2112static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2113 int connectable) 2114{ 2115 struct inode *inode = dentry->d_inode; 2116 2117 if (*len < 3) 2118 return 255; 2119 2120 if (hlist_unhashed(&inode->i_hash)) { 2121 /* Unfortunately insert_inode_hash is not idempotent, 2122 * so as we hash inodes here rather than at creation 2123 * time, we need a lock to ensure we only try 2124 * to do it once 2125 */ 2126 static DEFINE_SPINLOCK(lock); 2127 spin_lock(&lock); 2128 if (hlist_unhashed(&inode->i_hash)) 2129 __insert_inode_hash(inode, 2130 inode->i_ino + inode->i_generation); 2131 spin_unlock(&lock); 2132 } 2133 2134 fh[0] = inode->i_generation; 2135 fh[1] = inode->i_ino; 2136 fh[2] = ((__u64)inode->i_ino) >> 32; 2137 2138 *len = 3; 2139 return 1; 2140} 2141 2142static const struct export_operations shmem_export_ops = { 2143 .get_parent = shmem_get_parent, 2144 .encode_fh = shmem_encode_fh, 2145 .fh_to_dentry = shmem_fh_to_dentry, 2146}; 2147 2148static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 2149 bool remount) 2150{ 2151 char *this_char, *value, *rest; 2152 2153 while (options != NULL) { 2154 this_char = options; 2155 for (;;) { 2156 /* 2157 * NUL-terminate this option: unfortunately, 2158 * mount options form a comma-separated list, 2159 * but mpol's nodelist may also contain commas. 2160 */ 2161 options = strchr(options, ','); 2162 if (options == NULL) 2163 break; 2164 options++; 2165 if (!isdigit(*options)) { 2166 options[-1] = '\0'; 2167 break; 2168 } 2169 } 2170 if (!*this_char) 2171 continue; 2172 if ((value = strchr(this_char,'=')) != NULL) { 2173 *value++ = 0; 2174 } else { 2175 printk(KERN_ERR 2176 "tmpfs: No value for mount option '%s'\n", 2177 this_char); 2178 return 1; 2179 } 2180 2181 if (!strcmp(this_char,"size")) { 2182 unsigned long long size; 2183 size = memparse(value,&rest); 2184 if (*rest == '%') { 2185 size <<= PAGE_SHIFT; 2186 size *= totalram_pages; 2187 do_div(size, 100); 2188 rest++; 2189 } 2190 if (*rest) 2191 goto bad_val; 2192 sbinfo->max_blocks = 2193 DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2194 } else if (!strcmp(this_char,"nr_blocks")) { 2195 sbinfo->max_blocks = memparse(value, &rest); 2196 if (*rest) 2197 goto bad_val; 2198 } else if (!strcmp(this_char,"nr_inodes")) { 2199 sbinfo->max_inodes = memparse(value, &rest); 2200 if (*rest) 2201 goto bad_val; 2202 } else if (!strcmp(this_char,"mode")) { 2203 if (remount) 2204 continue; 2205 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; 2206 if (*rest) 2207 goto bad_val; 2208 } else if (!strcmp(this_char,"uid")) { 2209 if (remount) 2210 continue; 2211 sbinfo->uid = simple_strtoul(value, &rest, 0); 2212 if (*rest) 2213 goto bad_val; 2214 } else if (!strcmp(this_char,"gid")) { 2215 if (remount) 2216 continue; 2217 sbinfo->gid = simple_strtoul(value, &rest, 0); 2218 if (*rest) 2219 goto bad_val; 2220 } else if (!strcmp(this_char,"mpol")) { 2221 if (mpol_parse_str(value, &sbinfo->mpol, 1)) 2222 goto bad_val; 2223 } else { 2224 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2225 this_char); 2226 return 1; 2227 } 2228 } 2229 return 0; 2230 2231bad_val: 2232 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2233 value, this_char); 2234 return 1; 2235 2236} 2237 2238static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2239{ 2240 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2241 struct shmem_sb_info config = *sbinfo; 2242 unsigned long blocks; 2243 unsigned long inodes; 2244 int error = -EINVAL; 2245 2246 if (shmem_parse_options(data, &config, true)) 2247 return error; 2248 2249 spin_lock(&sbinfo->stat_lock); 2250 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2251 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2252 if (config.max_blocks < blocks) 2253 goto out; 2254 if (config.max_inodes < inodes) 2255 goto out; 2256 /* 2257 * Those tests also disallow limited->unlimited while any are in 2258 * use, so i_blocks will always be zero when max_blocks is zero; 2259 * but we must separately disallow unlimited->limited, because 2260 * in that case we have no record of how much is already in use. 2261 */ 2262 if (config.max_blocks && !sbinfo->max_blocks) 2263 goto out; 2264 if (config.max_inodes && !sbinfo->max_inodes) 2265 goto out; 2266 2267 error = 0; 2268 sbinfo->max_blocks = config.max_blocks; 2269 sbinfo->free_blocks = config.max_blocks - blocks; 2270 sbinfo->max_inodes = config.max_inodes; 2271 sbinfo->free_inodes = config.max_inodes - inodes; 2272 2273 mpol_put(sbinfo->mpol); 2274 sbinfo->mpol = config.mpol; /* transfers initial ref */ 2275out: 2276 spin_unlock(&sbinfo->stat_lock); 2277 return error; 2278} 2279 2280static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) 2281{ 2282 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); 2283 2284 if (sbinfo->max_blocks != shmem_default_max_blocks()) 2285 seq_printf(seq, ",size=%luk", 2286 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); 2287 if (sbinfo->max_inodes != shmem_default_max_inodes()) 2288 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); 2289 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) 2290 seq_printf(seq, ",mode=%03o", sbinfo->mode); 2291 if (sbinfo->uid != 0) 2292 seq_printf(seq, ",uid=%u", sbinfo->uid); 2293 if (sbinfo->gid != 0) 2294 seq_printf(seq, ",gid=%u", sbinfo->gid); 2295 shmem_show_mpol(seq, sbinfo->mpol); 2296 return 0; 2297} 2298#endif /* CONFIG_TMPFS */ 2299 2300static void shmem_put_super(struct super_block *sb) 2301{ 2302 kfree(sb->s_fs_info); 2303 sb->s_fs_info = NULL; 2304} 2305 2306int shmem_fill_super(struct super_block *sb, void *data, int silent) 2307{ 2308 struct inode *inode; 2309 struct dentry *root; 2310 struct shmem_sb_info *sbinfo; 2311 int err = -ENOMEM; 2312 2313 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2314 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), 2315 L1_CACHE_BYTES), GFP_KERNEL); 2316 if (!sbinfo) 2317 return -ENOMEM; 2318 2319 sbinfo->mode = S_IRWXUGO | S_ISVTX; 2320 sbinfo->uid = current_fsuid(); 2321 sbinfo->gid = current_fsgid(); 2322 sb->s_fs_info = sbinfo; 2323 2324#ifdef CONFIG_TMPFS 2325 /* 2326 * Per default we only allow half of the physical ram per 2327 * tmpfs instance, limiting inodes to one per page of lowmem; 2328 * but the internal instance is left unlimited. 2329 */ 2330 if (!(sb->s_flags & MS_NOUSER)) { 2331 sbinfo->max_blocks = shmem_default_max_blocks(); 2332 sbinfo->max_inodes = shmem_default_max_inodes(); 2333 if (shmem_parse_options(data, sbinfo, false)) { 2334 err = -EINVAL; 2335 goto failed; 2336 } 2337 } 2338 sb->s_export_op = &shmem_export_ops; 2339#else 2340 sb->s_flags |= MS_NOUSER; 2341#endif 2342 2343 spin_lock_init(&sbinfo->stat_lock); 2344 sbinfo->free_blocks = sbinfo->max_blocks; 2345 sbinfo->free_inodes = sbinfo->max_inodes; 2346 2347 sb->s_maxbytes = SHMEM_MAX_BYTES; 2348 sb->s_blocksize = PAGE_CACHE_SIZE; 2349 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2350 sb->s_magic = TMPFS_MAGIC; 2351 sb->s_op = &shmem_ops; 2352 sb->s_time_gran = 1; 2353#ifdef CONFIG_TMPFS_POSIX_ACL 2354 sb->s_xattr = shmem_xattr_handlers; 2355 sb->s_flags |= MS_POSIXACL; 2356#endif 2357 2358 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); 2359 if (!inode) 2360 goto failed; 2361 inode->i_uid = sbinfo->uid; 2362 inode->i_gid = sbinfo->gid; 2363 root = d_alloc_root(inode); 2364 if (!root) 2365 goto failed_iput; 2366 sb->s_root = root; 2367 return 0; 2368 2369failed_iput: 2370 iput(inode); 2371failed: 2372 shmem_put_super(sb); 2373 return err; 2374} 2375 2376static struct kmem_cache *shmem_inode_cachep; 2377 2378static struct inode *shmem_alloc_inode(struct super_block *sb) 2379{ 2380 struct shmem_inode_info *p; 2381 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2382 if (!p) 2383 return NULL; 2384 return &p->vfs_inode; 2385} 2386 2387static void shmem_destroy_inode(struct inode *inode) 2388{ 2389 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2390 /* only struct inode is valid if it's an inline symlink */ 2391 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2392 } 2393 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2394} 2395 2396static void init_once(void *foo) 2397{ 2398 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2399 2400 inode_init_once(&p->vfs_inode); 2401} 2402 2403static int init_inodecache(void) 2404{ 2405 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2406 sizeof(struct shmem_inode_info), 2407 0, SLAB_PANIC, init_once); 2408 return 0; 2409} 2410 2411static void destroy_inodecache(void) 2412{ 2413 kmem_cache_destroy(shmem_inode_cachep); 2414} 2415 2416static const struct address_space_operations shmem_aops = { 2417 .writepage = shmem_writepage, 2418 .set_page_dirty = __set_page_dirty_no_writeback, 2419#ifdef CONFIG_TMPFS 2420 .readpage = shmem_readpage, 2421 .write_begin = shmem_write_begin, 2422 .write_end = shmem_write_end, 2423#endif 2424 .migratepage = migrate_page, 2425 .error_remove_page = generic_error_remove_page, 2426}; 2427 2428static const struct file_operations shmem_file_operations = { 2429 .mmap = shmem_mmap, 2430#ifdef CONFIG_TMPFS 2431 .llseek = generic_file_llseek, 2432 .read = do_sync_read, 2433 .write = do_sync_write, 2434 .aio_read = shmem_file_aio_read, 2435 .aio_write = generic_file_aio_write, 2436 .fsync = noop_fsync, 2437 .splice_read = generic_file_splice_read, 2438 .splice_write = generic_file_splice_write, 2439#endif 2440}; 2441 2442static const struct inode_operations shmem_inode_operations = { 2443 .truncate = shmem_truncate, 2444 .setattr = shmem_notify_change, 2445 .truncate_range = shmem_truncate_range, 2446#ifdef CONFIG_TMPFS_POSIX_ACL 2447 .setxattr = generic_setxattr, 2448 .getxattr = generic_getxattr, 2449 .listxattr = generic_listxattr, 2450 .removexattr = generic_removexattr, 2451 .check_acl = generic_check_acl, 2452#endif 2453 2454}; 2455 2456static const struct inode_operations shmem_dir_inode_operations = { 2457#ifdef CONFIG_TMPFS 2458 .create = shmem_create, 2459 .lookup = simple_lookup, 2460 .link = shmem_link, 2461 .unlink = shmem_unlink, 2462 .symlink = shmem_symlink, 2463 .mkdir = shmem_mkdir, 2464 .rmdir = shmem_rmdir, 2465 .mknod = shmem_mknod, 2466 .rename = shmem_rename, 2467#endif 2468#ifdef CONFIG_TMPFS_POSIX_ACL 2469 .setattr = shmem_notify_change, 2470 .setxattr = generic_setxattr, 2471 .getxattr = generic_getxattr, 2472 .listxattr = generic_listxattr, 2473 .removexattr = generic_removexattr, 2474 .check_acl = generic_check_acl, 2475#endif 2476}; 2477 2478static const struct inode_operations shmem_special_inode_operations = { 2479#ifdef CONFIG_TMPFS_POSIX_ACL 2480 .setattr = shmem_notify_change, 2481 .setxattr = generic_setxattr, 2482 .getxattr = generic_getxattr, 2483 .listxattr = generic_listxattr, 2484 .removexattr = generic_removexattr, 2485 .check_acl = generic_check_acl, 2486#endif 2487}; 2488 2489static const struct super_operations shmem_ops = { 2490 .alloc_inode = shmem_alloc_inode, 2491 .destroy_inode = shmem_destroy_inode, 2492#ifdef CONFIG_TMPFS 2493 .statfs = shmem_statfs, 2494 .remount_fs = shmem_remount_fs, 2495 .show_options = shmem_show_options, 2496#endif 2497 .delete_inode = shmem_delete_inode, 2498 .drop_inode = generic_delete_inode, 2499 .put_super = shmem_put_super, 2500}; 2501 2502static const struct vm_operations_struct shmem_vm_ops = { 2503 .fault = shmem_fault, 2504#ifdef CONFIG_NUMA 2505 .set_policy = shmem_set_policy, 2506 .get_policy = shmem_get_policy, 2507#endif 2508}; 2509 2510 2511static int shmem_get_sb(struct file_system_type *fs_type, 2512 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2513{ 2514 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2515} 2516 2517static struct file_system_type tmpfs_fs_type = { 2518 .owner = THIS_MODULE, 2519 .name = "tmpfs", 2520 .get_sb = shmem_get_sb, 2521 .kill_sb = kill_litter_super, 2522}; 2523 2524int __init init_tmpfs(void) 2525{ 2526 int error; 2527 2528 error = bdi_init(&shmem_backing_dev_info); 2529 if (error) 2530 goto out4; 2531 2532 error = init_inodecache(); 2533 if (error) 2534 goto out3; 2535 2536 error = register_filesystem(&tmpfs_fs_type); 2537 if (error) { 2538 printk(KERN_ERR "Could not register tmpfs\n"); 2539 goto out2; 2540 } 2541 2542 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2543 tmpfs_fs_type.name, NULL); 2544 if (IS_ERR(shm_mnt)) { 2545 error = PTR_ERR(shm_mnt); 2546 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2547 goto out1; 2548 } 2549 return 0; 2550 2551out1: 2552 unregister_filesystem(&tmpfs_fs_type); 2553out2: 2554 destroy_inodecache(); 2555out3: 2556 bdi_destroy(&shmem_backing_dev_info); 2557out4: 2558 shm_mnt = ERR_PTR(error); 2559 return error; 2560} 2561 2562#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2563/** 2564 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2565 * @inode: the inode to be searched 2566 * @pgoff: the offset to be searched 2567 * @pagep: the pointer for the found page to be stored 2568 * @ent: the pointer for the found swap entry to be stored 2569 * 2570 * If a page is found, refcount of it is incremented. Callers should handle 2571 * these refcount. 2572 */ 2573void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2574 struct page **pagep, swp_entry_t *ent) 2575{ 2576 swp_entry_t entry = { .val = 0 }, *ptr; 2577 struct page *page = NULL; 2578 struct shmem_inode_info *info = SHMEM_I(inode); 2579 2580 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2581 goto out; 2582 2583 spin_lock(&info->lock); 2584 ptr = shmem_swp_entry(info, pgoff, NULL); 2585#ifdef CONFIG_SWAP 2586 if (ptr && ptr->val) { 2587 entry.val = ptr->val; 2588 page = find_get_page(&swapper_space, entry.val); 2589 } else 2590#endif 2591 page = find_get_page(inode->i_mapping, pgoff); 2592 if (ptr) 2593 shmem_swp_unmap(ptr); 2594 spin_unlock(&info->lock); 2595out: 2596 *pagep = page; 2597 *ent = entry; 2598} 2599#endif 2600 2601#else /* !CONFIG_SHMEM */ 2602 2603/* 2604 * tiny-shmem: simple shmemfs and tmpfs using ramfs code 2605 * 2606 * This is intended for small system where the benefits of the full 2607 * shmem code (swap-backed and resource-limited) are outweighed by 2608 * their complexity. On systems without swap this code should be 2609 * effectively equivalent, but much lighter weight. 2610 */ 2611 2612#include <linux/ramfs.h> 2613 2614static struct file_system_type tmpfs_fs_type = { 2615 .name = "tmpfs", 2616 .get_sb = ramfs_get_sb, 2617 .kill_sb = kill_litter_super, 2618}; 2619 2620int __init init_tmpfs(void) 2621{ 2622 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); 2623 2624 shm_mnt = kern_mount(&tmpfs_fs_type); 2625 BUG_ON(IS_ERR(shm_mnt)); 2626 2627 return 0; 2628} 2629 2630int shmem_unuse(swp_entry_t entry, struct page *page) 2631{ 2632 return 0; 2633} 2634 2635int shmem_lock(struct file *file, int lock, struct user_struct *user) 2636{ 2637 return 0; 2638} 2639 2640#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2641/** 2642 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2643 * @inode: the inode to be searched 2644 * @pgoff: the offset to be searched 2645 * @pagep: the pointer for the found page to be stored 2646 * @ent: the pointer for the found swap entry to be stored 2647 * 2648 * If a page is found, refcount of it is incremented. Callers should handle 2649 * these refcount. 2650 */ 2651void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2652 struct page **pagep, swp_entry_t *ent) 2653{ 2654 struct page *page = NULL; 2655 2656 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2657 goto out; 2658 page = find_get_page(inode->i_mapping, pgoff); 2659out: 2660 *pagep = page; 2661 *ent = (swp_entry_t){ .val = 0 }; 2662} 2663#endif 2664 2665#define shmem_vm_ops generic_file_vm_ops 2666#define shmem_file_operations ramfs_file_operations 2667#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) 2668#define shmem_acct_size(flags, size) 0 2669#define shmem_unacct_size(flags, size) do {} while (0) 2670#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE 2671 2672#endif /* CONFIG_SHMEM */ 2673 2674/* common code */ 2675 2676/** 2677 * shmem_file_setup - get an unlinked file living in tmpfs 2678 * @name: name for dentry (to be seen in /proc/<pid>/maps 2679 * @size: size to be set for the file 2680 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size 2681 */ 2682struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) 2683{ 2684 int error; 2685 struct file *file; 2686 struct inode *inode; 2687 struct path path; 2688 struct dentry *root; 2689 struct qstr this; 2690 2691 if (IS_ERR(shm_mnt)) 2692 return (void *)shm_mnt; 2693 2694 if (size < 0 || size > SHMEM_MAX_BYTES) 2695 return ERR_PTR(-EINVAL); 2696 2697 if (shmem_acct_size(flags, size)) 2698 return ERR_PTR(-ENOMEM); 2699 2700 error = -ENOMEM; 2701 this.name = name; 2702 this.len = strlen(name); 2703 this.hash = 0; /* will go */ 2704 root = shm_mnt->mnt_root; 2705 path.dentry = d_alloc(root, &this); 2706 if (!path.dentry) 2707 goto put_memory; 2708 path.mnt = mntget(shm_mnt); 2709 2710 error = -ENOSPC; 2711 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); 2712 if (!inode) 2713 goto put_dentry; 2714 2715 d_instantiate(path.dentry, inode); 2716 inode->i_size = size; 2717 inode->i_nlink = 0; /* It is unlinked */ 2718#ifndef CONFIG_MMU 2719 error = ramfs_nommu_expand_for_mapping(inode, size); 2720 if (error) 2721 goto put_dentry; 2722#endif 2723 2724 error = -ENFILE; 2725 file = alloc_file(&path, FMODE_WRITE | FMODE_READ, 2726 &shmem_file_operations); 2727 if (!file) 2728 goto put_dentry; 2729 2730 return file; 2731 2732put_dentry: 2733 path_put(&path); 2734put_memory: 2735 shmem_unacct_size(flags, size); 2736 return ERR_PTR(error); 2737} 2738EXPORT_SYMBOL_GPL(shmem_file_setup); 2739 2740/** 2741 * shmem_zero_setup - setup a shared anonymous mapping 2742 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2743 */ 2744int shmem_zero_setup(struct vm_area_struct *vma) 2745{ 2746 struct file *file; 2747 loff_t size = vma->vm_end - vma->vm_start; 2748 2749 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2750 if (IS_ERR(file)) 2751 return PTR_ERR(file); 2752 2753 if (vma->vm_file) 2754 fput(vma->vm_file); 2755 vma->vm_file = file; 2756 vma->vm_ops = &shmem_vm_ops; 2757 return 0; 2758} 2759