shmem.c revision 82369553d6d3bc67c54129a02e0bc0b5b88f3045
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 * This file is released under the GPL. 18 */ 19 20/* 21 * This virtual memory filesystem is heavily based on the ramfs. It 22 * extends ramfs by the ability to use swap and honor resource limits 23 * which makes it a completely usable filesystem. 24 */ 25 26#include <linux/module.h> 27#include <linux/init.h> 28#include <linux/fs.h> 29#include <linux/xattr.h> 30#include <linux/exportfs.h> 31#include <linux/generic_acl.h> 32#include <linux/mm.h> 33#include <linux/mman.h> 34#include <linux/file.h> 35#include <linux/swap.h> 36#include <linux/pagemap.h> 37#include <linux/string.h> 38#include <linux/slab.h> 39#include <linux/backing-dev.h> 40#include <linux/shmem_fs.h> 41#include <linux/mount.h> 42#include <linux/writeback.h> 43#include <linux/vfs.h> 44#include <linux/blkdev.h> 45#include <linux/security.h> 46#include <linux/swapops.h> 47#include <linux/mempolicy.h> 48#include <linux/namei.h> 49#include <linux/ctype.h> 50#include <linux/migrate.h> 51#include <linux/highmem.h> 52 53#include <asm/uaccess.h> 54#include <asm/div64.h> 55#include <asm/pgtable.h> 56 57/* This magic number is used in glibc for posix shared memory */ 58#define TMPFS_MAGIC 0x01021994 59 60#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 61#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 62#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 63 64#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 65#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 66 67#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 68 69/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 70#define SHMEM_PAGEIN VM_READ 71#define SHMEM_TRUNCATE VM_WRITE 72 73/* Definition to limit shmem_truncate's steps between cond_rescheds */ 74#define LATENCY_LIMIT 64 75 76/* Pretend that each entry is of this size in directory's i_size */ 77#define BOGO_DIRENT_SIZE 20 78 79/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 80enum sgp_type { 81 SGP_READ, /* don't exceed i_size, don't allocate page */ 82 SGP_CACHE, /* don't exceed i_size, may allocate page */ 83 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ 84 SGP_WRITE, /* may exceed i_size, may allocate page */ 85}; 86 87static int shmem_getpage(struct inode *inode, unsigned long idx, 88 struct page **pagep, enum sgp_type sgp, int *type); 89 90static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 91{ 92 /* 93 * The above definition of ENTRIES_PER_PAGE, and the use of 94 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 95 * might be reconsidered if it ever diverges from PAGE_SIZE. 96 * 97 * Mobility flags are masked out as swap vectors cannot move 98 */ 99 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, 100 PAGE_CACHE_SHIFT-PAGE_SHIFT); 101} 102 103static inline void shmem_dir_free(struct page *page) 104{ 105 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 106} 107 108static struct page **shmem_dir_map(struct page *page) 109{ 110 return (struct page **)kmap_atomic(page, KM_USER0); 111} 112 113static inline void shmem_dir_unmap(struct page **dir) 114{ 115 kunmap_atomic(dir, KM_USER0); 116} 117 118static swp_entry_t *shmem_swp_map(struct page *page) 119{ 120 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 121} 122 123static inline void shmem_swp_balance_unmap(void) 124{ 125 /* 126 * When passing a pointer to an i_direct entry, to code which 127 * also handles indirect entries and so will shmem_swp_unmap, 128 * we must arrange for the preempt count to remain in balance. 129 * What kmap_atomic of a lowmem page does depends on config 130 * and architecture, so pretend to kmap_atomic some lowmem page. 131 */ 132 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 133} 134 135static inline void shmem_swp_unmap(swp_entry_t *entry) 136{ 137 kunmap_atomic(entry, KM_USER1); 138} 139 140static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 141{ 142 return sb->s_fs_info; 143} 144 145/* 146 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 147 * for shared memory and for shared anonymous (/dev/zero) mappings 148 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 149 * consistent with the pre-accounting of private mappings ... 150 */ 151static inline int shmem_acct_size(unsigned long flags, loff_t size) 152{ 153 return (flags & VM_ACCOUNT)? 154 security_vm_enough_memory(VM_ACCT(size)): 0; 155} 156 157static inline void shmem_unacct_size(unsigned long flags, loff_t size) 158{ 159 if (flags & VM_ACCOUNT) 160 vm_unacct_memory(VM_ACCT(size)); 161} 162 163/* 164 * ... whereas tmpfs objects are accounted incrementally as 165 * pages are allocated, in order to allow huge sparse files. 166 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 167 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 168 */ 169static inline int shmem_acct_block(unsigned long flags) 170{ 171 return (flags & VM_ACCOUNT)? 172 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 173} 174 175static inline void shmem_unacct_blocks(unsigned long flags, long pages) 176{ 177 if (!(flags & VM_ACCOUNT)) 178 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 179} 180 181static const struct super_operations shmem_ops; 182static const struct address_space_operations shmem_aops; 183static const struct file_operations shmem_file_operations; 184static const struct inode_operations shmem_inode_operations; 185static const struct inode_operations shmem_dir_inode_operations; 186static const struct inode_operations shmem_special_inode_operations; 187static struct vm_operations_struct shmem_vm_ops; 188 189static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 190 .ra_pages = 0, /* No readahead */ 191 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 192 .unplug_io_fn = default_unplug_io_fn, 193}; 194 195static LIST_HEAD(shmem_swaplist); 196static DEFINE_MUTEX(shmem_swaplist_mutex); 197 198static void shmem_free_blocks(struct inode *inode, long pages) 199{ 200 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 201 if (sbinfo->max_blocks) { 202 spin_lock(&sbinfo->stat_lock); 203 sbinfo->free_blocks += pages; 204 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 205 spin_unlock(&sbinfo->stat_lock); 206 } 207} 208 209static int shmem_reserve_inode(struct super_block *sb) 210{ 211 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 212 if (sbinfo->max_inodes) { 213 spin_lock(&sbinfo->stat_lock); 214 if (!sbinfo->free_inodes) { 215 spin_unlock(&sbinfo->stat_lock); 216 return -ENOSPC; 217 } 218 sbinfo->free_inodes--; 219 spin_unlock(&sbinfo->stat_lock); 220 } 221 return 0; 222} 223 224static void shmem_free_inode(struct super_block *sb) 225{ 226 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 227 if (sbinfo->max_inodes) { 228 spin_lock(&sbinfo->stat_lock); 229 sbinfo->free_inodes++; 230 spin_unlock(&sbinfo->stat_lock); 231 } 232} 233 234/* 235 * shmem_recalc_inode - recalculate the size of an inode 236 * 237 * @inode: inode to recalc 238 * 239 * We have to calculate the free blocks since the mm can drop 240 * undirtied hole pages behind our back. 241 * 242 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 243 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 244 * 245 * It has to be called with the spinlock held. 246 */ 247static void shmem_recalc_inode(struct inode *inode) 248{ 249 struct shmem_inode_info *info = SHMEM_I(inode); 250 long freed; 251 252 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 253 if (freed > 0) { 254 info->alloced -= freed; 255 shmem_unacct_blocks(info->flags, freed); 256 shmem_free_blocks(inode, freed); 257 } 258} 259 260/* 261 * shmem_swp_entry - find the swap vector position in the info structure 262 * 263 * @info: info structure for the inode 264 * @index: index of the page to find 265 * @page: optional page to add to the structure. Has to be preset to 266 * all zeros 267 * 268 * If there is no space allocated yet it will return NULL when 269 * page is NULL, else it will use the page for the needed block, 270 * setting it to NULL on return to indicate that it has been used. 271 * 272 * The swap vector is organized the following way: 273 * 274 * There are SHMEM_NR_DIRECT entries directly stored in the 275 * shmem_inode_info structure. So small files do not need an addional 276 * allocation. 277 * 278 * For pages with index > SHMEM_NR_DIRECT there is the pointer 279 * i_indirect which points to a page which holds in the first half 280 * doubly indirect blocks, in the second half triple indirect blocks: 281 * 282 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 283 * following layout (for SHMEM_NR_DIRECT == 16): 284 * 285 * i_indirect -> dir --> 16-19 286 * | +-> 20-23 287 * | 288 * +-->dir2 --> 24-27 289 * | +-> 28-31 290 * | +-> 32-35 291 * | +-> 36-39 292 * | 293 * +-->dir3 --> 40-43 294 * +-> 44-47 295 * +-> 48-51 296 * +-> 52-55 297 */ 298static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 299{ 300 unsigned long offset; 301 struct page **dir; 302 struct page *subdir; 303 304 if (index < SHMEM_NR_DIRECT) { 305 shmem_swp_balance_unmap(); 306 return info->i_direct+index; 307 } 308 if (!info->i_indirect) { 309 if (page) { 310 info->i_indirect = *page; 311 *page = NULL; 312 } 313 return NULL; /* need another page */ 314 } 315 316 index -= SHMEM_NR_DIRECT; 317 offset = index % ENTRIES_PER_PAGE; 318 index /= ENTRIES_PER_PAGE; 319 dir = shmem_dir_map(info->i_indirect); 320 321 if (index >= ENTRIES_PER_PAGE/2) { 322 index -= ENTRIES_PER_PAGE/2; 323 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 324 index %= ENTRIES_PER_PAGE; 325 subdir = *dir; 326 if (!subdir) { 327 if (page) { 328 *dir = *page; 329 *page = NULL; 330 } 331 shmem_dir_unmap(dir); 332 return NULL; /* need another page */ 333 } 334 shmem_dir_unmap(dir); 335 dir = shmem_dir_map(subdir); 336 } 337 338 dir += index; 339 subdir = *dir; 340 if (!subdir) { 341 if (!page || !(subdir = *page)) { 342 shmem_dir_unmap(dir); 343 return NULL; /* need a page */ 344 } 345 *dir = subdir; 346 *page = NULL; 347 } 348 shmem_dir_unmap(dir); 349 return shmem_swp_map(subdir) + offset; 350} 351 352static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 353{ 354 long incdec = value? 1: -1; 355 356 entry->val = value; 357 info->swapped += incdec; 358 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 359 struct page *page = kmap_atomic_to_page(entry); 360 set_page_private(page, page_private(page) + incdec); 361 } 362} 363 364/* 365 * shmem_swp_alloc - get the position of the swap entry for the page. 366 * If it does not exist allocate the entry. 367 * 368 * @info: info structure for the inode 369 * @index: index of the page to find 370 * @sgp: check and recheck i_size? skip allocation? 371 */ 372static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 373{ 374 struct inode *inode = &info->vfs_inode; 375 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 376 struct page *page = NULL; 377 swp_entry_t *entry; 378 379 if (sgp != SGP_WRITE && 380 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 381 return ERR_PTR(-EINVAL); 382 383 while (!(entry = shmem_swp_entry(info, index, &page))) { 384 if (sgp == SGP_READ) 385 return shmem_swp_map(ZERO_PAGE(0)); 386 /* 387 * Test free_blocks against 1 not 0, since we have 1 data 388 * page (and perhaps indirect index pages) yet to allocate: 389 * a waste to allocate index if we cannot allocate data. 390 */ 391 if (sbinfo->max_blocks) { 392 spin_lock(&sbinfo->stat_lock); 393 if (sbinfo->free_blocks <= 1) { 394 spin_unlock(&sbinfo->stat_lock); 395 return ERR_PTR(-ENOSPC); 396 } 397 sbinfo->free_blocks--; 398 inode->i_blocks += BLOCKS_PER_PAGE; 399 spin_unlock(&sbinfo->stat_lock); 400 } 401 402 spin_unlock(&info->lock); 403 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); 404 if (page) 405 set_page_private(page, 0); 406 spin_lock(&info->lock); 407 408 if (!page) { 409 shmem_free_blocks(inode, 1); 410 return ERR_PTR(-ENOMEM); 411 } 412 if (sgp != SGP_WRITE && 413 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 414 entry = ERR_PTR(-EINVAL); 415 break; 416 } 417 if (info->next_index <= index) 418 info->next_index = index + 1; 419 } 420 if (page) { 421 /* another task gave its page, or truncated the file */ 422 shmem_free_blocks(inode, 1); 423 shmem_dir_free(page); 424 } 425 if (info->next_index <= index && !IS_ERR(entry)) 426 info->next_index = index + 1; 427 return entry; 428} 429 430/* 431 * shmem_free_swp - free some swap entries in a directory 432 * 433 * @dir: pointer to the directory 434 * @edir: pointer after last entry of the directory 435 * @punch_lock: pointer to spinlock when needed for the holepunch case 436 */ 437static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, 438 spinlock_t *punch_lock) 439{ 440 spinlock_t *punch_unlock = NULL; 441 swp_entry_t *ptr; 442 int freed = 0; 443 444 for (ptr = dir; ptr < edir; ptr++) { 445 if (ptr->val) { 446 if (unlikely(punch_lock)) { 447 punch_unlock = punch_lock; 448 punch_lock = NULL; 449 spin_lock(punch_unlock); 450 if (!ptr->val) 451 continue; 452 } 453 free_swap_and_cache(*ptr); 454 *ptr = (swp_entry_t){0}; 455 freed++; 456 } 457 } 458 if (punch_unlock) 459 spin_unlock(punch_unlock); 460 return freed; 461} 462 463static int shmem_map_and_free_swp(struct page *subdir, int offset, 464 int limit, struct page ***dir, spinlock_t *punch_lock) 465{ 466 swp_entry_t *ptr; 467 int freed = 0; 468 469 ptr = shmem_swp_map(subdir); 470 for (; offset < limit; offset += LATENCY_LIMIT) { 471 int size = limit - offset; 472 if (size > LATENCY_LIMIT) 473 size = LATENCY_LIMIT; 474 freed += shmem_free_swp(ptr+offset, ptr+offset+size, 475 punch_lock); 476 if (need_resched()) { 477 shmem_swp_unmap(ptr); 478 if (*dir) { 479 shmem_dir_unmap(*dir); 480 *dir = NULL; 481 } 482 cond_resched(); 483 ptr = shmem_swp_map(subdir); 484 } 485 } 486 shmem_swp_unmap(ptr); 487 return freed; 488} 489 490static void shmem_free_pages(struct list_head *next) 491{ 492 struct page *page; 493 int freed = 0; 494 495 do { 496 page = container_of(next, struct page, lru); 497 next = next->next; 498 shmem_dir_free(page); 499 freed++; 500 if (freed >= LATENCY_LIMIT) { 501 cond_resched(); 502 freed = 0; 503 } 504 } while (next); 505} 506 507static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 508{ 509 struct shmem_inode_info *info = SHMEM_I(inode); 510 unsigned long idx; 511 unsigned long size; 512 unsigned long limit; 513 unsigned long stage; 514 unsigned long diroff; 515 struct page **dir; 516 struct page *topdir; 517 struct page *middir; 518 struct page *subdir; 519 swp_entry_t *ptr; 520 LIST_HEAD(pages_to_free); 521 long nr_pages_to_free = 0; 522 long nr_swaps_freed = 0; 523 int offset; 524 int freed; 525 int punch_hole; 526 spinlock_t *needs_lock; 527 spinlock_t *punch_lock; 528 unsigned long upper_limit; 529 530 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 531 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 532 if (idx >= info->next_index) 533 return; 534 535 spin_lock(&info->lock); 536 info->flags |= SHMEM_TRUNCATE; 537 if (likely(end == (loff_t) -1)) { 538 limit = info->next_index; 539 upper_limit = SHMEM_MAX_INDEX; 540 info->next_index = idx; 541 needs_lock = NULL; 542 punch_hole = 0; 543 } else { 544 if (end + 1 >= inode->i_size) { /* we may free a little more */ 545 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> 546 PAGE_CACHE_SHIFT; 547 upper_limit = SHMEM_MAX_INDEX; 548 } else { 549 limit = (end + 1) >> PAGE_CACHE_SHIFT; 550 upper_limit = limit; 551 } 552 needs_lock = &info->lock; 553 punch_hole = 1; 554 } 555 556 topdir = info->i_indirect; 557 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 558 info->i_indirect = NULL; 559 nr_pages_to_free++; 560 list_add(&topdir->lru, &pages_to_free); 561 } 562 spin_unlock(&info->lock); 563 564 if (info->swapped && idx < SHMEM_NR_DIRECT) { 565 ptr = info->i_direct; 566 size = limit; 567 if (size > SHMEM_NR_DIRECT) 568 size = SHMEM_NR_DIRECT; 569 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); 570 } 571 572 /* 573 * If there are no indirect blocks or we are punching a hole 574 * below indirect blocks, nothing to be done. 575 */ 576 if (!topdir || limit <= SHMEM_NR_DIRECT) 577 goto done2; 578 579 /* 580 * The truncation case has already dropped info->lock, and we're safe 581 * because i_size and next_index have already been lowered, preventing 582 * access beyond. But in the punch_hole case, we still need to take 583 * the lock when updating the swap directory, because there might be 584 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or 585 * shmem_writepage. However, whenever we find we can remove a whole 586 * directory page (not at the misaligned start or end of the range), 587 * we first NULLify its pointer in the level above, and then have no 588 * need to take the lock when updating its contents: needs_lock and 589 * punch_lock (either pointing to info->lock or NULL) manage this. 590 */ 591 592 upper_limit -= SHMEM_NR_DIRECT; 593 limit -= SHMEM_NR_DIRECT; 594 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 595 offset = idx % ENTRIES_PER_PAGE; 596 idx -= offset; 597 598 dir = shmem_dir_map(topdir); 599 stage = ENTRIES_PER_PAGEPAGE/2; 600 if (idx < ENTRIES_PER_PAGEPAGE/2) { 601 middir = topdir; 602 diroff = idx/ENTRIES_PER_PAGE; 603 } else { 604 dir += ENTRIES_PER_PAGE/2; 605 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 606 while (stage <= idx) 607 stage += ENTRIES_PER_PAGEPAGE; 608 middir = *dir; 609 if (*dir) { 610 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 611 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 612 if (!diroff && !offset && upper_limit >= stage) { 613 if (needs_lock) { 614 spin_lock(needs_lock); 615 *dir = NULL; 616 spin_unlock(needs_lock); 617 needs_lock = NULL; 618 } else 619 *dir = NULL; 620 nr_pages_to_free++; 621 list_add(&middir->lru, &pages_to_free); 622 } 623 shmem_dir_unmap(dir); 624 dir = shmem_dir_map(middir); 625 } else { 626 diroff = 0; 627 offset = 0; 628 idx = stage; 629 } 630 } 631 632 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 633 if (unlikely(idx == stage)) { 634 shmem_dir_unmap(dir); 635 dir = shmem_dir_map(topdir) + 636 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 637 while (!*dir) { 638 dir++; 639 idx += ENTRIES_PER_PAGEPAGE; 640 if (idx >= limit) 641 goto done1; 642 } 643 stage = idx + ENTRIES_PER_PAGEPAGE; 644 middir = *dir; 645 if (punch_hole) 646 needs_lock = &info->lock; 647 if (upper_limit >= stage) { 648 if (needs_lock) { 649 spin_lock(needs_lock); 650 *dir = NULL; 651 spin_unlock(needs_lock); 652 needs_lock = NULL; 653 } else 654 *dir = NULL; 655 nr_pages_to_free++; 656 list_add(&middir->lru, &pages_to_free); 657 } 658 shmem_dir_unmap(dir); 659 cond_resched(); 660 dir = shmem_dir_map(middir); 661 diroff = 0; 662 } 663 punch_lock = needs_lock; 664 subdir = dir[diroff]; 665 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { 666 if (needs_lock) { 667 spin_lock(needs_lock); 668 dir[diroff] = NULL; 669 spin_unlock(needs_lock); 670 punch_lock = NULL; 671 } else 672 dir[diroff] = NULL; 673 nr_pages_to_free++; 674 list_add(&subdir->lru, &pages_to_free); 675 } 676 if (subdir && page_private(subdir) /* has swap entries */) { 677 size = limit - idx; 678 if (size > ENTRIES_PER_PAGE) 679 size = ENTRIES_PER_PAGE; 680 freed = shmem_map_and_free_swp(subdir, 681 offset, size, &dir, punch_lock); 682 if (!dir) 683 dir = shmem_dir_map(middir); 684 nr_swaps_freed += freed; 685 if (offset || punch_lock) { 686 spin_lock(&info->lock); 687 set_page_private(subdir, 688 page_private(subdir) - freed); 689 spin_unlock(&info->lock); 690 } else 691 BUG_ON(page_private(subdir) != freed); 692 } 693 offset = 0; 694 } 695done1: 696 shmem_dir_unmap(dir); 697done2: 698 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 699 /* 700 * Call truncate_inode_pages again: racing shmem_unuse_inode 701 * may have swizzled a page in from swap since vmtruncate or 702 * generic_delete_inode did it, before we lowered next_index. 703 * Also, though shmem_getpage checks i_size before adding to 704 * cache, no recheck after: so fix the narrow window there too. 705 * 706 * Recalling truncate_inode_pages_range and unmap_mapping_range 707 * every time for punch_hole (which never got a chance to clear 708 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 709 * yet hardly ever necessary: try to optimize them out later. 710 */ 711 truncate_inode_pages_range(inode->i_mapping, start, end); 712 if (punch_hole) 713 unmap_mapping_range(inode->i_mapping, start, 714 end - start, 1); 715 } 716 717 spin_lock(&info->lock); 718 info->flags &= ~SHMEM_TRUNCATE; 719 info->swapped -= nr_swaps_freed; 720 if (nr_pages_to_free) 721 shmem_free_blocks(inode, nr_pages_to_free); 722 shmem_recalc_inode(inode); 723 spin_unlock(&info->lock); 724 725 /* 726 * Empty swap vector directory pages to be freed? 727 */ 728 if (!list_empty(&pages_to_free)) { 729 pages_to_free.prev->next = NULL; 730 shmem_free_pages(pages_to_free.next); 731 } 732} 733 734static void shmem_truncate(struct inode *inode) 735{ 736 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 737} 738 739static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 740{ 741 struct inode *inode = dentry->d_inode; 742 struct page *page = NULL; 743 int error; 744 745 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 746 if (attr->ia_size < inode->i_size) { 747 /* 748 * If truncating down to a partial page, then 749 * if that page is already allocated, hold it 750 * in memory until the truncation is over, so 751 * truncate_partial_page cannnot miss it were 752 * it assigned to swap. 753 */ 754 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 755 (void) shmem_getpage(inode, 756 attr->ia_size>>PAGE_CACHE_SHIFT, 757 &page, SGP_READ, NULL); 758 if (page) 759 unlock_page(page); 760 } 761 /* 762 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 763 * detect if any pages might have been added to cache 764 * after truncate_inode_pages. But we needn't bother 765 * if it's being fully truncated to zero-length: the 766 * nrpages check is efficient enough in that case. 767 */ 768 if (attr->ia_size) { 769 struct shmem_inode_info *info = SHMEM_I(inode); 770 spin_lock(&info->lock); 771 info->flags &= ~SHMEM_PAGEIN; 772 spin_unlock(&info->lock); 773 } 774 } 775 } 776 777 error = inode_change_ok(inode, attr); 778 if (!error) 779 error = inode_setattr(inode, attr); 780#ifdef CONFIG_TMPFS_POSIX_ACL 781 if (!error && (attr->ia_valid & ATTR_MODE)) 782 error = generic_acl_chmod(inode, &shmem_acl_ops); 783#endif 784 if (page) 785 page_cache_release(page); 786 return error; 787} 788 789static void shmem_delete_inode(struct inode *inode) 790{ 791 struct shmem_inode_info *info = SHMEM_I(inode); 792 793 if (inode->i_op->truncate == shmem_truncate) { 794 truncate_inode_pages(inode->i_mapping, 0); 795 shmem_unacct_size(info->flags, inode->i_size); 796 inode->i_size = 0; 797 shmem_truncate(inode); 798 if (!list_empty(&info->swaplist)) { 799 mutex_lock(&shmem_swaplist_mutex); 800 list_del_init(&info->swaplist); 801 mutex_unlock(&shmem_swaplist_mutex); 802 } 803 } 804 BUG_ON(inode->i_blocks); 805 shmem_free_inode(inode->i_sb); 806 clear_inode(inode); 807} 808 809static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 810{ 811 swp_entry_t *ptr; 812 813 for (ptr = dir; ptr < edir; ptr++) { 814 if (ptr->val == entry.val) 815 return ptr - dir; 816 } 817 return -1; 818} 819 820static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 821{ 822 struct inode *inode; 823 unsigned long idx; 824 unsigned long size; 825 unsigned long limit; 826 unsigned long stage; 827 struct page **dir; 828 struct page *subdir; 829 swp_entry_t *ptr; 830 int offset; 831 int error; 832 833 idx = 0; 834 ptr = info->i_direct; 835 spin_lock(&info->lock); 836 if (!info->swapped) { 837 list_del_init(&info->swaplist); 838 goto lost2; 839 } 840 limit = info->next_index; 841 size = limit; 842 if (size > SHMEM_NR_DIRECT) 843 size = SHMEM_NR_DIRECT; 844 offset = shmem_find_swp(entry, ptr, ptr+size); 845 if (offset >= 0) 846 goto found; 847 if (!info->i_indirect) 848 goto lost2; 849 850 dir = shmem_dir_map(info->i_indirect); 851 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 852 853 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 854 if (unlikely(idx == stage)) { 855 shmem_dir_unmap(dir-1); 856 if (cond_resched_lock(&info->lock)) { 857 /* check it has not been truncated */ 858 if (limit > info->next_index) { 859 limit = info->next_index; 860 if (idx >= limit) 861 goto lost2; 862 } 863 } 864 dir = shmem_dir_map(info->i_indirect) + 865 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 866 while (!*dir) { 867 dir++; 868 idx += ENTRIES_PER_PAGEPAGE; 869 if (idx >= limit) 870 goto lost1; 871 } 872 stage = idx + ENTRIES_PER_PAGEPAGE; 873 subdir = *dir; 874 shmem_dir_unmap(dir); 875 dir = shmem_dir_map(subdir); 876 } 877 subdir = *dir; 878 if (subdir && page_private(subdir)) { 879 ptr = shmem_swp_map(subdir); 880 size = limit - idx; 881 if (size > ENTRIES_PER_PAGE) 882 size = ENTRIES_PER_PAGE; 883 offset = shmem_find_swp(entry, ptr, ptr+size); 884 shmem_swp_unmap(ptr); 885 if (offset >= 0) { 886 shmem_dir_unmap(dir); 887 goto found; 888 } 889 } 890 } 891lost1: 892 shmem_dir_unmap(dir-1); 893lost2: 894 spin_unlock(&info->lock); 895 return 0; 896found: 897 idx += offset; 898 inode = igrab(&info->vfs_inode); 899 spin_unlock(&info->lock); 900 901 /* 902 * Move _head_ to start search for next from here. 903 * But be careful: shmem_delete_inode checks list_empty without taking 904 * mutex, and there's an instant in list_move_tail when info->swaplist 905 * would appear empty, if it were the only one on shmem_swaplist. We 906 * could avoid doing it if inode NULL; or use this minor optimization. 907 */ 908 if (shmem_swaplist.next != &info->swaplist) 909 list_move_tail(&shmem_swaplist, &info->swaplist); 910 mutex_unlock(&shmem_swaplist_mutex); 911 912 error = 1; 913 if (!inode) 914 goto out; 915 /* Precharge page while we can wait, compensate afterwards */ 916 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); 917 if (error) 918 goto out; 919 error = radix_tree_preload(GFP_KERNEL); 920 if (error) 921 goto uncharge; 922 error = 1; 923 924 spin_lock(&info->lock); 925 ptr = shmem_swp_entry(info, idx, NULL); 926 if (ptr && ptr->val == entry.val) 927 error = add_to_page_cache(page, inode->i_mapping, 928 idx, GFP_NOWAIT); 929 if (error == -EEXIST) { 930 struct page *filepage = find_get_page(inode->i_mapping, idx); 931 error = 1; 932 if (filepage) { 933 /* 934 * There might be a more uptodate page coming down 935 * from a stacked writepage: forget our swappage if so. 936 */ 937 if (PageUptodate(filepage)) 938 error = 0; 939 page_cache_release(filepage); 940 } 941 } 942 if (!error) { 943 delete_from_swap_cache(page); 944 set_page_dirty(page); 945 info->flags |= SHMEM_PAGEIN; 946 shmem_swp_set(info, ptr, 0); 947 swap_free(entry); 948 error = 1; /* not an error, but entry was found */ 949 } 950 if (ptr) 951 shmem_swp_unmap(ptr); 952 spin_unlock(&info->lock); 953 radix_tree_preload_end(); 954uncharge: 955 mem_cgroup_uncharge_page(page); 956out: 957 unlock_page(page); 958 page_cache_release(page); 959 iput(inode); /* allows for NULL */ 960 return error; 961} 962 963/* 964 * shmem_unuse() search for an eventually swapped out shmem page. 965 */ 966int shmem_unuse(swp_entry_t entry, struct page *page) 967{ 968 struct list_head *p, *next; 969 struct shmem_inode_info *info; 970 int found = 0; 971 972 mutex_lock(&shmem_swaplist_mutex); 973 list_for_each_safe(p, next, &shmem_swaplist) { 974 info = list_entry(p, struct shmem_inode_info, swaplist); 975 found = shmem_unuse_inode(info, entry, page); 976 cond_resched(); 977 if (found) 978 goto out; 979 } 980 mutex_unlock(&shmem_swaplist_mutex); 981out: return found; /* 0 or 1 or -ENOMEM */ 982} 983 984/* 985 * Move the page from the page cache to the swap cache. 986 */ 987static int shmem_writepage(struct page *page, struct writeback_control *wbc) 988{ 989 struct shmem_inode_info *info; 990 swp_entry_t *entry, swap; 991 struct address_space *mapping; 992 unsigned long index; 993 struct inode *inode; 994 995 BUG_ON(!PageLocked(page)); 996 mapping = page->mapping; 997 index = page->index; 998 inode = mapping->host; 999 info = SHMEM_I(inode); 1000 if (info->flags & VM_LOCKED) 1001 goto redirty; 1002 if (!total_swap_pages) 1003 goto redirty; 1004 1005 /* 1006 * shmem_backing_dev_info's capabilities prevent regular writeback or 1007 * sync from ever calling shmem_writepage; but a stacking filesystem 1008 * may use the ->writepage of its underlying filesystem, in which case 1009 * tmpfs should write out to swap only in response to memory pressure, 1010 * and not for pdflush or sync. However, in those cases, we do still 1011 * want to check if there's a redundant swappage to be discarded. 1012 */ 1013 if (wbc->for_reclaim) 1014 swap = get_swap_page(); 1015 else 1016 swap.val = 0; 1017 1018 spin_lock(&info->lock); 1019 if (index >= info->next_index) { 1020 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1021 goto unlock; 1022 } 1023 entry = shmem_swp_entry(info, index, NULL); 1024 if (entry->val) { 1025 /* 1026 * The more uptodate page coming down from a stacked 1027 * writepage should replace our old swappage. 1028 */ 1029 free_swap_and_cache(*entry); 1030 shmem_swp_set(info, entry, 0); 1031 } 1032 shmem_recalc_inode(inode); 1033 1034 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1035 remove_from_page_cache(page); 1036 shmem_swp_set(info, entry, swap.val); 1037 shmem_swp_unmap(entry); 1038 if (list_empty(&info->swaplist)) 1039 inode = igrab(inode); 1040 else 1041 inode = NULL; 1042 spin_unlock(&info->lock); 1043 swap_duplicate(swap); 1044 BUG_ON(page_mapped(page)); 1045 page_cache_release(page); /* pagecache ref */ 1046 set_page_dirty(page); 1047 unlock_page(page); 1048 if (inode) { 1049 mutex_lock(&shmem_swaplist_mutex); 1050 /* move instead of add in case we're racing */ 1051 list_move_tail(&info->swaplist, &shmem_swaplist); 1052 mutex_unlock(&shmem_swaplist_mutex); 1053 iput(inode); 1054 } 1055 return 0; 1056 } 1057 1058 shmem_swp_unmap(entry); 1059unlock: 1060 spin_unlock(&info->lock); 1061 swap_free(swap); 1062redirty: 1063 set_page_dirty(page); 1064 if (wbc->for_reclaim) 1065 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1066 unlock_page(page); 1067 return 0; 1068} 1069 1070#ifdef CONFIG_NUMA 1071static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 1072{ 1073 char *nodelist = strchr(value, ':'); 1074 int err = 1; 1075 1076 if (nodelist) { 1077 /* NUL-terminate policy string */ 1078 *nodelist++ = '\0'; 1079 if (nodelist_parse(nodelist, *policy_nodes)) 1080 goto out; 1081 if (!nodes_subset(*policy_nodes, node_states[N_HIGH_MEMORY])) 1082 goto out; 1083 } 1084 if (!strcmp(value, "default")) { 1085 *policy = MPOL_DEFAULT; 1086 /* Don't allow a nodelist */ 1087 if (!nodelist) 1088 err = 0; 1089 } else if (!strcmp(value, "prefer")) { 1090 *policy = MPOL_PREFERRED; 1091 /* Insist on a nodelist of one node only */ 1092 if (nodelist) { 1093 char *rest = nodelist; 1094 while (isdigit(*rest)) 1095 rest++; 1096 if (!*rest) 1097 err = 0; 1098 } 1099 } else if (!strcmp(value, "bind")) { 1100 *policy = MPOL_BIND; 1101 /* Insist on a nodelist */ 1102 if (nodelist) 1103 err = 0; 1104 } else if (!strcmp(value, "interleave")) { 1105 *policy = MPOL_INTERLEAVE; 1106 /* 1107 * Default to online nodes with memory if no nodelist 1108 */ 1109 if (!nodelist) 1110 *policy_nodes = node_states[N_HIGH_MEMORY]; 1111 err = 0; 1112 } 1113out: 1114 /* Restore string for error message */ 1115 if (nodelist) 1116 *--nodelist = ':'; 1117 return err; 1118} 1119 1120static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1121 struct shmem_inode_info *info, unsigned long idx) 1122{ 1123 struct vm_area_struct pvma; 1124 struct page *page; 1125 1126 /* Create a pseudo vma that just contains the policy */ 1127 pvma.vm_start = 0; 1128 pvma.vm_pgoff = idx; 1129 pvma.vm_ops = NULL; 1130 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1131 page = swapin_readahead(entry, gfp, &pvma, 0); 1132 mpol_free(pvma.vm_policy); 1133 return page; 1134} 1135 1136static struct page *shmem_alloc_page(gfp_t gfp, 1137 struct shmem_inode_info *info, unsigned long idx) 1138{ 1139 struct vm_area_struct pvma; 1140 struct page *page; 1141 1142 /* Create a pseudo vma that just contains the policy */ 1143 pvma.vm_start = 0; 1144 pvma.vm_pgoff = idx; 1145 pvma.vm_ops = NULL; 1146 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1147 page = alloc_page_vma(gfp, &pvma, 0); 1148 mpol_free(pvma.vm_policy); 1149 return page; 1150} 1151#else 1152static inline int shmem_parse_mpol(char *value, int *policy, 1153 nodemask_t *policy_nodes) 1154{ 1155 return 1; 1156} 1157 1158static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1159 struct shmem_inode_info *info, unsigned long idx) 1160{ 1161 return swapin_readahead(entry, gfp, NULL, 0); 1162} 1163 1164static inline struct page *shmem_alloc_page(gfp_t gfp, 1165 struct shmem_inode_info *info, unsigned long idx) 1166{ 1167 return alloc_page(gfp); 1168} 1169#endif 1170 1171/* 1172 * shmem_getpage - either get the page from swap or allocate a new one 1173 * 1174 * If we allocate a new one we do not mark it dirty. That's up to the 1175 * vm. If we swap it in we mark it dirty since we also free the swap 1176 * entry since a page cannot live in both the swap and page cache 1177 */ 1178static int shmem_getpage(struct inode *inode, unsigned long idx, 1179 struct page **pagep, enum sgp_type sgp, int *type) 1180{ 1181 struct address_space *mapping = inode->i_mapping; 1182 struct shmem_inode_info *info = SHMEM_I(inode); 1183 struct shmem_sb_info *sbinfo; 1184 struct page *filepage = *pagep; 1185 struct page *swappage; 1186 swp_entry_t *entry; 1187 swp_entry_t swap; 1188 gfp_t gfp; 1189 int error; 1190 1191 if (idx >= SHMEM_MAX_INDEX) 1192 return -EFBIG; 1193 1194 if (type) 1195 *type = 0; 1196 1197 /* 1198 * Normally, filepage is NULL on entry, and either found 1199 * uptodate immediately, or allocated and zeroed, or read 1200 * in under swappage, which is then assigned to filepage. 1201 * But shmem_readpage (required for splice) passes in a locked 1202 * filepage, which may be found not uptodate by other callers 1203 * too, and may need to be copied from the swappage read in. 1204 */ 1205repeat: 1206 if (!filepage) 1207 filepage = find_lock_page(mapping, idx); 1208 if (filepage && PageUptodate(filepage)) 1209 goto done; 1210 error = 0; 1211 gfp = mapping_gfp_mask(mapping); 1212 if (!filepage) { 1213 /* 1214 * Try to preload while we can wait, to not make a habit of 1215 * draining atomic reserves; but don't latch on to this cpu. 1216 */ 1217 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1218 if (error) 1219 goto failed; 1220 radix_tree_preload_end(); 1221 } 1222 1223 spin_lock(&info->lock); 1224 shmem_recalc_inode(inode); 1225 entry = shmem_swp_alloc(info, idx, sgp); 1226 if (IS_ERR(entry)) { 1227 spin_unlock(&info->lock); 1228 error = PTR_ERR(entry); 1229 goto failed; 1230 } 1231 swap = *entry; 1232 1233 if (swap.val) { 1234 /* Look it up and read it in.. */ 1235 swappage = lookup_swap_cache(swap); 1236 if (!swappage) { 1237 shmem_swp_unmap(entry); 1238 /* here we actually do the io */ 1239 if (type && !(*type & VM_FAULT_MAJOR)) { 1240 __count_vm_event(PGMAJFAULT); 1241 *type |= VM_FAULT_MAJOR; 1242 } 1243 spin_unlock(&info->lock); 1244 swappage = shmem_swapin(swap, gfp, info, idx); 1245 if (!swappage) { 1246 spin_lock(&info->lock); 1247 entry = shmem_swp_alloc(info, idx, sgp); 1248 if (IS_ERR(entry)) 1249 error = PTR_ERR(entry); 1250 else { 1251 if (entry->val == swap.val) 1252 error = -ENOMEM; 1253 shmem_swp_unmap(entry); 1254 } 1255 spin_unlock(&info->lock); 1256 if (error) 1257 goto failed; 1258 goto repeat; 1259 } 1260 wait_on_page_locked(swappage); 1261 page_cache_release(swappage); 1262 goto repeat; 1263 } 1264 1265 /* We have to do this with page locked to prevent races */ 1266 if (TestSetPageLocked(swappage)) { 1267 shmem_swp_unmap(entry); 1268 spin_unlock(&info->lock); 1269 wait_on_page_locked(swappage); 1270 page_cache_release(swappage); 1271 goto repeat; 1272 } 1273 if (PageWriteback(swappage)) { 1274 shmem_swp_unmap(entry); 1275 spin_unlock(&info->lock); 1276 wait_on_page_writeback(swappage); 1277 unlock_page(swappage); 1278 page_cache_release(swappage); 1279 goto repeat; 1280 } 1281 if (!PageUptodate(swappage)) { 1282 shmem_swp_unmap(entry); 1283 spin_unlock(&info->lock); 1284 unlock_page(swappage); 1285 page_cache_release(swappage); 1286 error = -EIO; 1287 goto failed; 1288 } 1289 1290 if (filepage) { 1291 shmem_swp_set(info, entry, 0); 1292 shmem_swp_unmap(entry); 1293 delete_from_swap_cache(swappage); 1294 spin_unlock(&info->lock); 1295 copy_highpage(filepage, swappage); 1296 unlock_page(swappage); 1297 page_cache_release(swappage); 1298 flush_dcache_page(filepage); 1299 SetPageUptodate(filepage); 1300 set_page_dirty(filepage); 1301 swap_free(swap); 1302 } else if (!(error = add_to_page_cache( 1303 swappage, mapping, idx, GFP_NOWAIT))) { 1304 info->flags |= SHMEM_PAGEIN; 1305 shmem_swp_set(info, entry, 0); 1306 shmem_swp_unmap(entry); 1307 delete_from_swap_cache(swappage); 1308 spin_unlock(&info->lock); 1309 filepage = swappage; 1310 set_page_dirty(filepage); 1311 swap_free(swap); 1312 } else { 1313 shmem_swp_unmap(entry); 1314 spin_unlock(&info->lock); 1315 unlock_page(swappage); 1316 page_cache_release(swappage); 1317 if (error == -ENOMEM) { 1318 /* allow reclaim from this memory cgroup */ 1319 error = mem_cgroup_cache_charge(NULL, 1320 current->mm, gfp & ~__GFP_HIGHMEM); 1321 if (error) 1322 goto failed; 1323 } 1324 goto repeat; 1325 } 1326 } else if (sgp == SGP_READ && !filepage) { 1327 shmem_swp_unmap(entry); 1328 filepage = find_get_page(mapping, idx); 1329 if (filepage && 1330 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1331 spin_unlock(&info->lock); 1332 wait_on_page_locked(filepage); 1333 page_cache_release(filepage); 1334 filepage = NULL; 1335 goto repeat; 1336 } 1337 spin_unlock(&info->lock); 1338 } else { 1339 shmem_swp_unmap(entry); 1340 sbinfo = SHMEM_SB(inode->i_sb); 1341 if (sbinfo->max_blocks) { 1342 spin_lock(&sbinfo->stat_lock); 1343 if (sbinfo->free_blocks == 0 || 1344 shmem_acct_block(info->flags)) { 1345 spin_unlock(&sbinfo->stat_lock); 1346 spin_unlock(&info->lock); 1347 error = -ENOSPC; 1348 goto failed; 1349 } 1350 sbinfo->free_blocks--; 1351 inode->i_blocks += BLOCKS_PER_PAGE; 1352 spin_unlock(&sbinfo->stat_lock); 1353 } else if (shmem_acct_block(info->flags)) { 1354 spin_unlock(&info->lock); 1355 error = -ENOSPC; 1356 goto failed; 1357 } 1358 1359 if (!filepage) { 1360 spin_unlock(&info->lock); 1361 filepage = shmem_alloc_page(gfp, info, idx); 1362 if (!filepage) { 1363 shmem_unacct_blocks(info->flags, 1); 1364 shmem_free_blocks(inode, 1); 1365 error = -ENOMEM; 1366 goto failed; 1367 } 1368 1369 /* Precharge page while we can wait, compensate after */ 1370 error = mem_cgroup_cache_charge(filepage, current->mm, 1371 gfp & ~__GFP_HIGHMEM); 1372 if (error) { 1373 page_cache_release(filepage); 1374 shmem_unacct_blocks(info->flags, 1); 1375 shmem_free_blocks(inode, 1); 1376 filepage = NULL; 1377 goto failed; 1378 } 1379 1380 spin_lock(&info->lock); 1381 entry = shmem_swp_alloc(info, idx, sgp); 1382 if (IS_ERR(entry)) 1383 error = PTR_ERR(entry); 1384 else { 1385 swap = *entry; 1386 shmem_swp_unmap(entry); 1387 } 1388 if (error || swap.val || 0 != add_to_page_cache_lru( 1389 filepage, mapping, idx, GFP_NOWAIT)) { 1390 spin_unlock(&info->lock); 1391 mem_cgroup_uncharge_page(filepage); 1392 page_cache_release(filepage); 1393 shmem_unacct_blocks(info->flags, 1); 1394 shmem_free_blocks(inode, 1); 1395 filepage = NULL; 1396 if (error) 1397 goto failed; 1398 goto repeat; 1399 } 1400 mem_cgroup_uncharge_page(filepage); 1401 info->flags |= SHMEM_PAGEIN; 1402 } 1403 1404 info->alloced++; 1405 spin_unlock(&info->lock); 1406 clear_highpage(filepage); 1407 flush_dcache_page(filepage); 1408 SetPageUptodate(filepage); 1409 if (sgp == SGP_DIRTY) 1410 set_page_dirty(filepage); 1411 } 1412done: 1413 *pagep = filepage; 1414 return 0; 1415 1416failed: 1417 if (*pagep != filepage) { 1418 unlock_page(filepage); 1419 page_cache_release(filepage); 1420 } 1421 return error; 1422} 1423 1424static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1425{ 1426 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1427 int error; 1428 int ret; 1429 1430 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1431 return VM_FAULT_SIGBUS; 1432 1433 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1434 if (error) 1435 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1436 1437 mark_page_accessed(vmf->page); 1438 return ret | VM_FAULT_LOCKED; 1439} 1440 1441#ifdef CONFIG_NUMA 1442static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1443{ 1444 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1445 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1446} 1447 1448static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1449 unsigned long addr) 1450{ 1451 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1452 unsigned long idx; 1453 1454 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1455 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1456} 1457#endif 1458 1459int shmem_lock(struct file *file, int lock, struct user_struct *user) 1460{ 1461 struct inode *inode = file->f_path.dentry->d_inode; 1462 struct shmem_inode_info *info = SHMEM_I(inode); 1463 int retval = -ENOMEM; 1464 1465 spin_lock(&info->lock); 1466 if (lock && !(info->flags & VM_LOCKED)) { 1467 if (!user_shm_lock(inode->i_size, user)) 1468 goto out_nomem; 1469 info->flags |= VM_LOCKED; 1470 } 1471 if (!lock && (info->flags & VM_LOCKED) && user) { 1472 user_shm_unlock(inode->i_size, user); 1473 info->flags &= ~VM_LOCKED; 1474 } 1475 retval = 0; 1476out_nomem: 1477 spin_unlock(&info->lock); 1478 return retval; 1479} 1480 1481static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1482{ 1483 file_accessed(file); 1484 vma->vm_ops = &shmem_vm_ops; 1485 vma->vm_flags |= VM_CAN_NONLINEAR; 1486 return 0; 1487} 1488 1489static struct inode * 1490shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1491{ 1492 struct inode *inode; 1493 struct shmem_inode_info *info; 1494 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1495 1496 if (shmem_reserve_inode(sb)) 1497 return NULL; 1498 1499 inode = new_inode(sb); 1500 if (inode) { 1501 inode->i_mode = mode; 1502 inode->i_uid = current->fsuid; 1503 inode->i_gid = current->fsgid; 1504 inode->i_blocks = 0; 1505 inode->i_mapping->a_ops = &shmem_aops; 1506 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1507 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1508 inode->i_generation = get_seconds(); 1509 info = SHMEM_I(inode); 1510 memset(info, 0, (char *)inode - (char *)info); 1511 spin_lock_init(&info->lock); 1512 INIT_LIST_HEAD(&info->swaplist); 1513 1514 switch (mode & S_IFMT) { 1515 default: 1516 inode->i_op = &shmem_special_inode_operations; 1517 init_special_inode(inode, mode, dev); 1518 break; 1519 case S_IFREG: 1520 inode->i_op = &shmem_inode_operations; 1521 inode->i_fop = &shmem_file_operations; 1522 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1523 &sbinfo->policy_nodes); 1524 break; 1525 case S_IFDIR: 1526 inc_nlink(inode); 1527 /* Some things misbehave if size == 0 on a directory */ 1528 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1529 inode->i_op = &shmem_dir_inode_operations; 1530 inode->i_fop = &simple_dir_operations; 1531 break; 1532 case S_IFLNK: 1533 /* 1534 * Must not load anything in the rbtree, 1535 * mpol_free_shared_policy will not be called. 1536 */ 1537 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1538 NULL); 1539 break; 1540 } 1541 } else 1542 shmem_free_inode(sb); 1543 return inode; 1544} 1545 1546#ifdef CONFIG_TMPFS 1547static const struct inode_operations shmem_symlink_inode_operations; 1548static const struct inode_operations shmem_symlink_inline_operations; 1549 1550/* 1551 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1552 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1553 * below the loop driver, in the generic fashion that many filesystems support. 1554 */ 1555static int shmem_readpage(struct file *file, struct page *page) 1556{ 1557 struct inode *inode = page->mapping->host; 1558 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1559 unlock_page(page); 1560 return error; 1561} 1562 1563static int 1564shmem_write_begin(struct file *file, struct address_space *mapping, 1565 loff_t pos, unsigned len, unsigned flags, 1566 struct page **pagep, void **fsdata) 1567{ 1568 struct inode *inode = mapping->host; 1569 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1570 *pagep = NULL; 1571 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1572} 1573 1574static int 1575shmem_write_end(struct file *file, struct address_space *mapping, 1576 loff_t pos, unsigned len, unsigned copied, 1577 struct page *page, void *fsdata) 1578{ 1579 struct inode *inode = mapping->host; 1580 1581 if (pos + copied > inode->i_size) 1582 i_size_write(inode, pos + copied); 1583 1584 unlock_page(page); 1585 set_page_dirty(page); 1586 page_cache_release(page); 1587 1588 return copied; 1589} 1590 1591static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1592{ 1593 struct inode *inode = filp->f_path.dentry->d_inode; 1594 struct address_space *mapping = inode->i_mapping; 1595 unsigned long index, offset; 1596 enum sgp_type sgp = SGP_READ; 1597 1598 /* 1599 * Might this read be for a stacking filesystem? Then when reading 1600 * holes of a sparse file, we actually need to allocate those pages, 1601 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1602 */ 1603 if (segment_eq(get_fs(), KERNEL_DS)) 1604 sgp = SGP_DIRTY; 1605 1606 index = *ppos >> PAGE_CACHE_SHIFT; 1607 offset = *ppos & ~PAGE_CACHE_MASK; 1608 1609 for (;;) { 1610 struct page *page = NULL; 1611 unsigned long end_index, nr, ret; 1612 loff_t i_size = i_size_read(inode); 1613 1614 end_index = i_size >> PAGE_CACHE_SHIFT; 1615 if (index > end_index) 1616 break; 1617 if (index == end_index) { 1618 nr = i_size & ~PAGE_CACHE_MASK; 1619 if (nr <= offset) 1620 break; 1621 } 1622 1623 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1624 if (desc->error) { 1625 if (desc->error == -EINVAL) 1626 desc->error = 0; 1627 break; 1628 } 1629 if (page) 1630 unlock_page(page); 1631 1632 /* 1633 * We must evaluate after, since reads (unlike writes) 1634 * are called without i_mutex protection against truncate 1635 */ 1636 nr = PAGE_CACHE_SIZE; 1637 i_size = i_size_read(inode); 1638 end_index = i_size >> PAGE_CACHE_SHIFT; 1639 if (index == end_index) { 1640 nr = i_size & ~PAGE_CACHE_MASK; 1641 if (nr <= offset) { 1642 if (page) 1643 page_cache_release(page); 1644 break; 1645 } 1646 } 1647 nr -= offset; 1648 1649 if (page) { 1650 /* 1651 * If users can be writing to this page using arbitrary 1652 * virtual addresses, take care about potential aliasing 1653 * before reading the page on the kernel side. 1654 */ 1655 if (mapping_writably_mapped(mapping)) 1656 flush_dcache_page(page); 1657 /* 1658 * Mark the page accessed if we read the beginning. 1659 */ 1660 if (!offset) 1661 mark_page_accessed(page); 1662 } else { 1663 page = ZERO_PAGE(0); 1664 page_cache_get(page); 1665 } 1666 1667 /* 1668 * Ok, we have the page, and it's up-to-date, so 1669 * now we can copy it to user space... 1670 * 1671 * The actor routine returns how many bytes were actually used.. 1672 * NOTE! This may not be the same as how much of a user buffer 1673 * we filled up (we may be padding etc), so we can only update 1674 * "pos" here (the actor routine has to update the user buffer 1675 * pointers and the remaining count). 1676 */ 1677 ret = actor(desc, page, offset, nr); 1678 offset += ret; 1679 index += offset >> PAGE_CACHE_SHIFT; 1680 offset &= ~PAGE_CACHE_MASK; 1681 1682 page_cache_release(page); 1683 if (ret != nr || !desc->count) 1684 break; 1685 1686 cond_resched(); 1687 } 1688 1689 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1690 file_accessed(filp); 1691} 1692 1693static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1694{ 1695 read_descriptor_t desc; 1696 1697 if ((ssize_t) count < 0) 1698 return -EINVAL; 1699 if (!access_ok(VERIFY_WRITE, buf, count)) 1700 return -EFAULT; 1701 if (!count) 1702 return 0; 1703 1704 desc.written = 0; 1705 desc.count = count; 1706 desc.arg.buf = buf; 1707 desc.error = 0; 1708 1709 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1710 if (desc.written) 1711 return desc.written; 1712 return desc.error; 1713} 1714 1715static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1716{ 1717 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1718 1719 buf->f_type = TMPFS_MAGIC; 1720 buf->f_bsize = PAGE_CACHE_SIZE; 1721 buf->f_namelen = NAME_MAX; 1722 spin_lock(&sbinfo->stat_lock); 1723 if (sbinfo->max_blocks) { 1724 buf->f_blocks = sbinfo->max_blocks; 1725 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1726 } 1727 if (sbinfo->max_inodes) { 1728 buf->f_files = sbinfo->max_inodes; 1729 buf->f_ffree = sbinfo->free_inodes; 1730 } 1731 /* else leave those fields 0 like simple_statfs */ 1732 spin_unlock(&sbinfo->stat_lock); 1733 return 0; 1734} 1735 1736/* 1737 * File creation. Allocate an inode, and we're done.. 1738 */ 1739static int 1740shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1741{ 1742 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1743 int error = -ENOSPC; 1744 1745 if (inode) { 1746 error = security_inode_init_security(inode, dir, NULL, NULL, 1747 NULL); 1748 if (error) { 1749 if (error != -EOPNOTSUPP) { 1750 iput(inode); 1751 return error; 1752 } 1753 } 1754 error = shmem_acl_init(inode, dir); 1755 if (error) { 1756 iput(inode); 1757 return error; 1758 } 1759 if (dir->i_mode & S_ISGID) { 1760 inode->i_gid = dir->i_gid; 1761 if (S_ISDIR(mode)) 1762 inode->i_mode |= S_ISGID; 1763 } 1764 dir->i_size += BOGO_DIRENT_SIZE; 1765 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1766 d_instantiate(dentry, inode); 1767 dget(dentry); /* Extra count - pin the dentry in core */ 1768 } 1769 return error; 1770} 1771 1772static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1773{ 1774 int error; 1775 1776 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1777 return error; 1778 inc_nlink(dir); 1779 return 0; 1780} 1781 1782static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1783 struct nameidata *nd) 1784{ 1785 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1786} 1787 1788/* 1789 * Link a file.. 1790 */ 1791static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1792{ 1793 struct inode *inode = old_dentry->d_inode; 1794 int ret; 1795 1796 /* 1797 * No ordinary (disk based) filesystem counts links as inodes; 1798 * but each new link needs a new dentry, pinning lowmem, and 1799 * tmpfs dentries cannot be pruned until they are unlinked. 1800 */ 1801 ret = shmem_reserve_inode(inode->i_sb); 1802 if (ret) 1803 goto out; 1804 1805 dir->i_size += BOGO_DIRENT_SIZE; 1806 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1807 inc_nlink(inode); 1808 atomic_inc(&inode->i_count); /* New dentry reference */ 1809 dget(dentry); /* Extra pinning count for the created dentry */ 1810 d_instantiate(dentry, inode); 1811out: 1812 return ret; 1813} 1814 1815static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1816{ 1817 struct inode *inode = dentry->d_inode; 1818 1819 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1820 shmem_free_inode(inode->i_sb); 1821 1822 dir->i_size -= BOGO_DIRENT_SIZE; 1823 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1824 drop_nlink(inode); 1825 dput(dentry); /* Undo the count from "create" - this does all the work */ 1826 return 0; 1827} 1828 1829static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1830{ 1831 if (!simple_empty(dentry)) 1832 return -ENOTEMPTY; 1833 1834 drop_nlink(dentry->d_inode); 1835 drop_nlink(dir); 1836 return shmem_unlink(dir, dentry); 1837} 1838 1839/* 1840 * The VFS layer already does all the dentry stuff for rename, 1841 * we just have to decrement the usage count for the target if 1842 * it exists so that the VFS layer correctly free's it when it 1843 * gets overwritten. 1844 */ 1845static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1846{ 1847 struct inode *inode = old_dentry->d_inode; 1848 int they_are_dirs = S_ISDIR(inode->i_mode); 1849 1850 if (!simple_empty(new_dentry)) 1851 return -ENOTEMPTY; 1852 1853 if (new_dentry->d_inode) { 1854 (void) shmem_unlink(new_dir, new_dentry); 1855 if (they_are_dirs) 1856 drop_nlink(old_dir); 1857 } else if (they_are_dirs) { 1858 drop_nlink(old_dir); 1859 inc_nlink(new_dir); 1860 } 1861 1862 old_dir->i_size -= BOGO_DIRENT_SIZE; 1863 new_dir->i_size += BOGO_DIRENT_SIZE; 1864 old_dir->i_ctime = old_dir->i_mtime = 1865 new_dir->i_ctime = new_dir->i_mtime = 1866 inode->i_ctime = CURRENT_TIME; 1867 return 0; 1868} 1869 1870static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1871{ 1872 int error; 1873 int len; 1874 struct inode *inode; 1875 struct page *page = NULL; 1876 char *kaddr; 1877 struct shmem_inode_info *info; 1878 1879 len = strlen(symname) + 1; 1880 if (len > PAGE_CACHE_SIZE) 1881 return -ENAMETOOLONG; 1882 1883 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1884 if (!inode) 1885 return -ENOSPC; 1886 1887 error = security_inode_init_security(inode, dir, NULL, NULL, 1888 NULL); 1889 if (error) { 1890 if (error != -EOPNOTSUPP) { 1891 iput(inode); 1892 return error; 1893 } 1894 error = 0; 1895 } 1896 1897 info = SHMEM_I(inode); 1898 inode->i_size = len-1; 1899 if (len <= (char *)inode - (char *)info) { 1900 /* do it inline */ 1901 memcpy(info, symname, len); 1902 inode->i_op = &shmem_symlink_inline_operations; 1903 } else { 1904 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1905 if (error) { 1906 iput(inode); 1907 return error; 1908 } 1909 unlock_page(page); 1910 inode->i_op = &shmem_symlink_inode_operations; 1911 kaddr = kmap_atomic(page, KM_USER0); 1912 memcpy(kaddr, symname, len); 1913 kunmap_atomic(kaddr, KM_USER0); 1914 set_page_dirty(page); 1915 page_cache_release(page); 1916 } 1917 if (dir->i_mode & S_ISGID) 1918 inode->i_gid = dir->i_gid; 1919 dir->i_size += BOGO_DIRENT_SIZE; 1920 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1921 d_instantiate(dentry, inode); 1922 dget(dentry); 1923 return 0; 1924} 1925 1926static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1927{ 1928 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1929 return NULL; 1930} 1931 1932static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1933{ 1934 struct page *page = NULL; 1935 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1936 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1937 if (page) 1938 unlock_page(page); 1939 return page; 1940} 1941 1942static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1943{ 1944 if (!IS_ERR(nd_get_link(nd))) { 1945 struct page *page = cookie; 1946 kunmap(page); 1947 mark_page_accessed(page); 1948 page_cache_release(page); 1949 } 1950} 1951 1952static const struct inode_operations shmem_symlink_inline_operations = { 1953 .readlink = generic_readlink, 1954 .follow_link = shmem_follow_link_inline, 1955}; 1956 1957static const struct inode_operations shmem_symlink_inode_operations = { 1958 .truncate = shmem_truncate, 1959 .readlink = generic_readlink, 1960 .follow_link = shmem_follow_link, 1961 .put_link = shmem_put_link, 1962}; 1963 1964#ifdef CONFIG_TMPFS_POSIX_ACL 1965/** 1966 * Superblocks without xattr inode operations will get security.* xattr 1967 * support from the VFS "for free". As soon as we have any other xattrs 1968 * like ACLs, we also need to implement the security.* handlers at 1969 * filesystem level, though. 1970 */ 1971 1972static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1973 size_t list_len, const char *name, 1974 size_t name_len) 1975{ 1976 return security_inode_listsecurity(inode, list, list_len); 1977} 1978 1979static int shmem_xattr_security_get(struct inode *inode, const char *name, 1980 void *buffer, size_t size) 1981{ 1982 if (strcmp(name, "") == 0) 1983 return -EINVAL; 1984 return xattr_getsecurity(inode, name, buffer, size); 1985} 1986 1987static int shmem_xattr_security_set(struct inode *inode, const char *name, 1988 const void *value, size_t size, int flags) 1989{ 1990 if (strcmp(name, "") == 0) 1991 return -EINVAL; 1992 return security_inode_setsecurity(inode, name, value, size, flags); 1993} 1994 1995static struct xattr_handler shmem_xattr_security_handler = { 1996 .prefix = XATTR_SECURITY_PREFIX, 1997 .list = shmem_xattr_security_list, 1998 .get = shmem_xattr_security_get, 1999 .set = shmem_xattr_security_set, 2000}; 2001 2002static struct xattr_handler *shmem_xattr_handlers[] = { 2003 &shmem_xattr_acl_access_handler, 2004 &shmem_xattr_acl_default_handler, 2005 &shmem_xattr_security_handler, 2006 NULL 2007}; 2008#endif 2009 2010static struct dentry *shmem_get_parent(struct dentry *child) 2011{ 2012 return ERR_PTR(-ESTALE); 2013} 2014 2015static int shmem_match(struct inode *ino, void *vfh) 2016{ 2017 __u32 *fh = vfh; 2018 __u64 inum = fh[2]; 2019 inum = (inum << 32) | fh[1]; 2020 return ino->i_ino == inum && fh[0] == ino->i_generation; 2021} 2022 2023static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2024 struct fid *fid, int fh_len, int fh_type) 2025{ 2026 struct inode *inode; 2027 struct dentry *dentry = NULL; 2028 u64 inum = fid->raw[2]; 2029 inum = (inum << 32) | fid->raw[1]; 2030 2031 if (fh_len < 3) 2032 return NULL; 2033 2034 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2035 shmem_match, fid->raw); 2036 if (inode) { 2037 dentry = d_find_alias(inode); 2038 iput(inode); 2039 } 2040 2041 return dentry; 2042} 2043 2044static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2045 int connectable) 2046{ 2047 struct inode *inode = dentry->d_inode; 2048 2049 if (*len < 3) 2050 return 255; 2051 2052 if (hlist_unhashed(&inode->i_hash)) { 2053 /* Unfortunately insert_inode_hash is not idempotent, 2054 * so as we hash inodes here rather than at creation 2055 * time, we need a lock to ensure we only try 2056 * to do it once 2057 */ 2058 static DEFINE_SPINLOCK(lock); 2059 spin_lock(&lock); 2060 if (hlist_unhashed(&inode->i_hash)) 2061 __insert_inode_hash(inode, 2062 inode->i_ino + inode->i_generation); 2063 spin_unlock(&lock); 2064 } 2065 2066 fh[0] = inode->i_generation; 2067 fh[1] = inode->i_ino; 2068 fh[2] = ((__u64)inode->i_ino) >> 32; 2069 2070 *len = 3; 2071 return 1; 2072} 2073 2074static const struct export_operations shmem_export_ops = { 2075 .get_parent = shmem_get_parent, 2076 .encode_fh = shmem_encode_fh, 2077 .fh_to_dentry = shmem_fh_to_dentry, 2078}; 2079 2080static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2081 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2082 int *policy, nodemask_t *policy_nodes) 2083{ 2084 char *this_char, *value, *rest; 2085 2086 while (options != NULL) { 2087 this_char = options; 2088 for (;;) { 2089 /* 2090 * NUL-terminate this option: unfortunately, 2091 * mount options form a comma-separated list, 2092 * but mpol's nodelist may also contain commas. 2093 */ 2094 options = strchr(options, ','); 2095 if (options == NULL) 2096 break; 2097 options++; 2098 if (!isdigit(*options)) { 2099 options[-1] = '\0'; 2100 break; 2101 } 2102 } 2103 if (!*this_char) 2104 continue; 2105 if ((value = strchr(this_char,'=')) != NULL) { 2106 *value++ = 0; 2107 } else { 2108 printk(KERN_ERR 2109 "tmpfs: No value for mount option '%s'\n", 2110 this_char); 2111 return 1; 2112 } 2113 2114 if (!strcmp(this_char,"size")) { 2115 unsigned long long size; 2116 size = memparse(value,&rest); 2117 if (*rest == '%') { 2118 size <<= PAGE_SHIFT; 2119 size *= totalram_pages; 2120 do_div(size, 100); 2121 rest++; 2122 } 2123 if (*rest) 2124 goto bad_val; 2125 *blocks = DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2126 } else if (!strcmp(this_char,"nr_blocks")) { 2127 *blocks = memparse(value,&rest); 2128 if (*rest) 2129 goto bad_val; 2130 } else if (!strcmp(this_char,"nr_inodes")) { 2131 *inodes = memparse(value,&rest); 2132 if (*rest) 2133 goto bad_val; 2134 } else if (!strcmp(this_char,"mode")) { 2135 if (!mode) 2136 continue; 2137 *mode = simple_strtoul(value,&rest,8); 2138 if (*rest) 2139 goto bad_val; 2140 } else if (!strcmp(this_char,"uid")) { 2141 if (!uid) 2142 continue; 2143 *uid = simple_strtoul(value,&rest,0); 2144 if (*rest) 2145 goto bad_val; 2146 } else if (!strcmp(this_char,"gid")) { 2147 if (!gid) 2148 continue; 2149 *gid = simple_strtoul(value,&rest,0); 2150 if (*rest) 2151 goto bad_val; 2152 } else if (!strcmp(this_char,"mpol")) { 2153 if (shmem_parse_mpol(value,policy,policy_nodes)) 2154 goto bad_val; 2155 } else { 2156 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2157 this_char); 2158 return 1; 2159 } 2160 } 2161 return 0; 2162 2163bad_val: 2164 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2165 value, this_char); 2166 return 1; 2167 2168} 2169 2170static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2171{ 2172 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2173 unsigned long max_blocks = sbinfo->max_blocks; 2174 unsigned long max_inodes = sbinfo->max_inodes; 2175 int policy = sbinfo->policy; 2176 nodemask_t policy_nodes = sbinfo->policy_nodes; 2177 unsigned long blocks; 2178 unsigned long inodes; 2179 int error = -EINVAL; 2180 2181 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2182 &max_inodes, &policy, &policy_nodes)) 2183 return error; 2184 2185 spin_lock(&sbinfo->stat_lock); 2186 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2187 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2188 if (max_blocks < blocks) 2189 goto out; 2190 if (max_inodes < inodes) 2191 goto out; 2192 /* 2193 * Those tests also disallow limited->unlimited while any are in 2194 * use, so i_blocks will always be zero when max_blocks is zero; 2195 * but we must separately disallow unlimited->limited, because 2196 * in that case we have no record of how much is already in use. 2197 */ 2198 if (max_blocks && !sbinfo->max_blocks) 2199 goto out; 2200 if (max_inodes && !sbinfo->max_inodes) 2201 goto out; 2202 2203 error = 0; 2204 sbinfo->max_blocks = max_blocks; 2205 sbinfo->free_blocks = max_blocks - blocks; 2206 sbinfo->max_inodes = max_inodes; 2207 sbinfo->free_inodes = max_inodes - inodes; 2208 sbinfo->policy = policy; 2209 sbinfo->policy_nodes = policy_nodes; 2210out: 2211 spin_unlock(&sbinfo->stat_lock); 2212 return error; 2213} 2214#endif 2215 2216static void shmem_put_super(struct super_block *sb) 2217{ 2218 kfree(sb->s_fs_info); 2219 sb->s_fs_info = NULL; 2220} 2221 2222static int shmem_fill_super(struct super_block *sb, 2223 void *data, int silent) 2224{ 2225 struct inode *inode; 2226 struct dentry *root; 2227 int mode = S_IRWXUGO | S_ISVTX; 2228 uid_t uid = current->fsuid; 2229 gid_t gid = current->fsgid; 2230 int err = -ENOMEM; 2231 struct shmem_sb_info *sbinfo; 2232 unsigned long blocks = 0; 2233 unsigned long inodes = 0; 2234 int policy = MPOL_DEFAULT; 2235 nodemask_t policy_nodes = node_states[N_HIGH_MEMORY]; 2236 2237#ifdef CONFIG_TMPFS 2238 /* 2239 * Per default we only allow half of the physical ram per 2240 * tmpfs instance, limiting inodes to one per page of lowmem; 2241 * but the internal instance is left unlimited. 2242 */ 2243 if (!(sb->s_flags & MS_NOUSER)) { 2244 blocks = totalram_pages / 2; 2245 inodes = totalram_pages - totalhigh_pages; 2246 if (inodes > blocks) 2247 inodes = blocks; 2248 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2249 &inodes, &policy, &policy_nodes)) 2250 return -EINVAL; 2251 } 2252 sb->s_export_op = &shmem_export_ops; 2253#else 2254 sb->s_flags |= MS_NOUSER; 2255#endif 2256 2257 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2258 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2259 L1_CACHE_BYTES), GFP_KERNEL); 2260 if (!sbinfo) 2261 return -ENOMEM; 2262 2263 spin_lock_init(&sbinfo->stat_lock); 2264 sbinfo->max_blocks = blocks; 2265 sbinfo->free_blocks = blocks; 2266 sbinfo->max_inodes = inodes; 2267 sbinfo->free_inodes = inodes; 2268 sbinfo->policy = policy; 2269 sbinfo->policy_nodes = policy_nodes; 2270 2271 sb->s_fs_info = sbinfo; 2272 sb->s_maxbytes = SHMEM_MAX_BYTES; 2273 sb->s_blocksize = PAGE_CACHE_SIZE; 2274 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2275 sb->s_magic = TMPFS_MAGIC; 2276 sb->s_op = &shmem_ops; 2277 sb->s_time_gran = 1; 2278#ifdef CONFIG_TMPFS_POSIX_ACL 2279 sb->s_xattr = shmem_xattr_handlers; 2280 sb->s_flags |= MS_POSIXACL; 2281#endif 2282 2283 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2284 if (!inode) 2285 goto failed; 2286 inode->i_uid = uid; 2287 inode->i_gid = gid; 2288 root = d_alloc_root(inode); 2289 if (!root) 2290 goto failed_iput; 2291 sb->s_root = root; 2292 return 0; 2293 2294failed_iput: 2295 iput(inode); 2296failed: 2297 shmem_put_super(sb); 2298 return err; 2299} 2300 2301static struct kmem_cache *shmem_inode_cachep; 2302 2303static struct inode *shmem_alloc_inode(struct super_block *sb) 2304{ 2305 struct shmem_inode_info *p; 2306 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2307 if (!p) 2308 return NULL; 2309 return &p->vfs_inode; 2310} 2311 2312static void shmem_destroy_inode(struct inode *inode) 2313{ 2314 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2315 /* only struct inode is valid if it's an inline symlink */ 2316 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2317 } 2318 shmem_acl_destroy_inode(inode); 2319 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2320} 2321 2322static void init_once(struct kmem_cache *cachep, void *foo) 2323{ 2324 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2325 2326 inode_init_once(&p->vfs_inode); 2327#ifdef CONFIG_TMPFS_POSIX_ACL 2328 p->i_acl = NULL; 2329 p->i_default_acl = NULL; 2330#endif 2331} 2332 2333static int init_inodecache(void) 2334{ 2335 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2336 sizeof(struct shmem_inode_info), 2337 0, SLAB_PANIC, init_once); 2338 return 0; 2339} 2340 2341static void destroy_inodecache(void) 2342{ 2343 kmem_cache_destroy(shmem_inode_cachep); 2344} 2345 2346static const struct address_space_operations shmem_aops = { 2347 .writepage = shmem_writepage, 2348 .set_page_dirty = __set_page_dirty_no_writeback, 2349#ifdef CONFIG_TMPFS 2350 .readpage = shmem_readpage, 2351 .write_begin = shmem_write_begin, 2352 .write_end = shmem_write_end, 2353#endif 2354 .migratepage = migrate_page, 2355}; 2356 2357static const struct file_operations shmem_file_operations = { 2358 .mmap = shmem_mmap, 2359#ifdef CONFIG_TMPFS 2360 .llseek = generic_file_llseek, 2361 .read = shmem_file_read, 2362 .write = do_sync_write, 2363 .aio_write = generic_file_aio_write, 2364 .fsync = simple_sync_file, 2365 .splice_read = generic_file_splice_read, 2366 .splice_write = generic_file_splice_write, 2367#endif 2368}; 2369 2370static const struct inode_operations shmem_inode_operations = { 2371 .truncate = shmem_truncate, 2372 .setattr = shmem_notify_change, 2373 .truncate_range = shmem_truncate_range, 2374#ifdef CONFIG_TMPFS_POSIX_ACL 2375 .setxattr = generic_setxattr, 2376 .getxattr = generic_getxattr, 2377 .listxattr = generic_listxattr, 2378 .removexattr = generic_removexattr, 2379 .permission = shmem_permission, 2380#endif 2381 2382}; 2383 2384static const struct inode_operations shmem_dir_inode_operations = { 2385#ifdef CONFIG_TMPFS 2386 .create = shmem_create, 2387 .lookup = simple_lookup, 2388 .link = shmem_link, 2389 .unlink = shmem_unlink, 2390 .symlink = shmem_symlink, 2391 .mkdir = shmem_mkdir, 2392 .rmdir = shmem_rmdir, 2393 .mknod = shmem_mknod, 2394 .rename = shmem_rename, 2395#endif 2396#ifdef CONFIG_TMPFS_POSIX_ACL 2397 .setattr = shmem_notify_change, 2398 .setxattr = generic_setxattr, 2399 .getxattr = generic_getxattr, 2400 .listxattr = generic_listxattr, 2401 .removexattr = generic_removexattr, 2402 .permission = shmem_permission, 2403#endif 2404}; 2405 2406static const struct inode_operations shmem_special_inode_operations = { 2407#ifdef CONFIG_TMPFS_POSIX_ACL 2408 .setattr = shmem_notify_change, 2409 .setxattr = generic_setxattr, 2410 .getxattr = generic_getxattr, 2411 .listxattr = generic_listxattr, 2412 .removexattr = generic_removexattr, 2413 .permission = shmem_permission, 2414#endif 2415}; 2416 2417static const struct super_operations shmem_ops = { 2418 .alloc_inode = shmem_alloc_inode, 2419 .destroy_inode = shmem_destroy_inode, 2420#ifdef CONFIG_TMPFS 2421 .statfs = shmem_statfs, 2422 .remount_fs = shmem_remount_fs, 2423#endif 2424 .delete_inode = shmem_delete_inode, 2425 .drop_inode = generic_delete_inode, 2426 .put_super = shmem_put_super, 2427}; 2428 2429static struct vm_operations_struct shmem_vm_ops = { 2430 .fault = shmem_fault, 2431#ifdef CONFIG_NUMA 2432 .set_policy = shmem_set_policy, 2433 .get_policy = shmem_get_policy, 2434#endif 2435}; 2436 2437 2438static int shmem_get_sb(struct file_system_type *fs_type, 2439 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2440{ 2441 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2442} 2443 2444static struct file_system_type tmpfs_fs_type = { 2445 .owner = THIS_MODULE, 2446 .name = "tmpfs", 2447 .get_sb = shmem_get_sb, 2448 .kill_sb = kill_litter_super, 2449}; 2450static struct vfsmount *shm_mnt; 2451 2452static int __init init_tmpfs(void) 2453{ 2454 int error; 2455 2456 error = bdi_init(&shmem_backing_dev_info); 2457 if (error) 2458 goto out4; 2459 2460 error = init_inodecache(); 2461 if (error) 2462 goto out3; 2463 2464 error = register_filesystem(&tmpfs_fs_type); 2465 if (error) { 2466 printk(KERN_ERR "Could not register tmpfs\n"); 2467 goto out2; 2468 } 2469 2470 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2471 tmpfs_fs_type.name, NULL); 2472 if (IS_ERR(shm_mnt)) { 2473 error = PTR_ERR(shm_mnt); 2474 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2475 goto out1; 2476 } 2477 return 0; 2478 2479out1: 2480 unregister_filesystem(&tmpfs_fs_type); 2481out2: 2482 destroy_inodecache(); 2483out3: 2484 bdi_destroy(&shmem_backing_dev_info); 2485out4: 2486 shm_mnt = ERR_PTR(error); 2487 return error; 2488} 2489module_init(init_tmpfs) 2490 2491/* 2492 * shmem_file_setup - get an unlinked file living in tmpfs 2493 * 2494 * @name: name for dentry (to be seen in /proc/<pid>/maps 2495 * @size: size to be set for the file 2496 * 2497 */ 2498struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2499{ 2500 int error; 2501 struct file *file; 2502 struct inode *inode; 2503 struct dentry *dentry, *root; 2504 struct qstr this; 2505 2506 if (IS_ERR(shm_mnt)) 2507 return (void *)shm_mnt; 2508 2509 if (size < 0 || size > SHMEM_MAX_BYTES) 2510 return ERR_PTR(-EINVAL); 2511 2512 if (shmem_acct_size(flags, size)) 2513 return ERR_PTR(-ENOMEM); 2514 2515 error = -ENOMEM; 2516 this.name = name; 2517 this.len = strlen(name); 2518 this.hash = 0; /* will go */ 2519 root = shm_mnt->mnt_root; 2520 dentry = d_alloc(root, &this); 2521 if (!dentry) 2522 goto put_memory; 2523 2524 error = -ENFILE; 2525 file = get_empty_filp(); 2526 if (!file) 2527 goto put_dentry; 2528 2529 error = -ENOSPC; 2530 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2531 if (!inode) 2532 goto close_file; 2533 2534 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2535 d_instantiate(dentry, inode); 2536 inode->i_size = size; 2537 inode->i_nlink = 0; /* It is unlinked */ 2538 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ, 2539 &shmem_file_operations); 2540 return file; 2541 2542close_file: 2543 put_filp(file); 2544put_dentry: 2545 dput(dentry); 2546put_memory: 2547 shmem_unacct_size(flags, size); 2548 return ERR_PTR(error); 2549} 2550 2551/* 2552 * shmem_zero_setup - setup a shared anonymous mapping 2553 * 2554 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2555 */ 2556int shmem_zero_setup(struct vm_area_struct *vma) 2557{ 2558 struct file *file; 2559 loff_t size = vma->vm_end - vma->vm_start; 2560 2561 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2562 if (IS_ERR(file)) 2563 return PTR_ERR(file); 2564 2565 if (vma->vm_file) 2566 fput(vma->vm_file); 2567 vma->vm_file = file; 2568 vma->vm_ops = &shmem_vm_ops; 2569 return 0; 2570} 2571