shmem.c revision a0ee5ec520ede1dc8e2194623bcebfd9fab408f2
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_SPINLOCK(shmem_swaplist_lock); 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 spin_lock(&shmem_swaplist_lock); 800 list_del_init(&info->swaplist); 801 spin_unlock(&shmem_swaplist_lock); 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 limit = info->next_index; 837 size = limit; 838 if (size > SHMEM_NR_DIRECT) 839 size = SHMEM_NR_DIRECT; 840 offset = shmem_find_swp(entry, ptr, ptr+size); 841 if (offset >= 0) { 842 shmem_swp_balance_unmap(); 843 goto found; 844 } 845 if (!info->i_indirect) 846 goto lost2; 847 848 dir = shmem_dir_map(info->i_indirect); 849 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 850 851 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 852 if (unlikely(idx == stage)) { 853 shmem_dir_unmap(dir-1); 854 dir = shmem_dir_map(info->i_indirect) + 855 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 856 while (!*dir) { 857 dir++; 858 idx += ENTRIES_PER_PAGEPAGE; 859 if (idx >= limit) 860 goto lost1; 861 } 862 stage = idx + ENTRIES_PER_PAGEPAGE; 863 subdir = *dir; 864 shmem_dir_unmap(dir); 865 dir = shmem_dir_map(subdir); 866 } 867 subdir = *dir; 868 if (subdir && page_private(subdir)) { 869 ptr = shmem_swp_map(subdir); 870 size = limit - idx; 871 if (size > ENTRIES_PER_PAGE) 872 size = ENTRIES_PER_PAGE; 873 offset = shmem_find_swp(entry, ptr, ptr+size); 874 if (offset >= 0) { 875 shmem_dir_unmap(dir); 876 goto found; 877 } 878 shmem_swp_unmap(ptr); 879 } 880 } 881lost1: 882 shmem_dir_unmap(dir-1); 883lost2: 884 spin_unlock(&info->lock); 885 return 0; 886found: 887 idx += offset; 888 inode = &info->vfs_inode; 889 error = add_to_page_cache(page, inode->i_mapping, idx, GFP_ATOMIC); 890 if (error == -EEXIST) { 891 struct page *filepage = find_get_page(inode->i_mapping, idx); 892 if (filepage) { 893 /* 894 * There might be a more uptodate page coming down 895 * from a stacked writepage: forget our swappage if so. 896 */ 897 if (PageUptodate(filepage)) 898 error = 0; 899 page_cache_release(filepage); 900 } 901 } 902 if (!error) { 903 delete_from_swap_cache(page); 904 set_page_dirty(page); 905 info->flags |= SHMEM_PAGEIN; 906 shmem_swp_set(info, ptr + offset, 0); 907 } 908 shmem_swp_unmap(ptr); 909 spin_unlock(&info->lock); 910 /* 911 * Decrement swap count even when the entry is left behind: 912 * try_to_unuse will skip over mms, then reincrement count. 913 */ 914 swap_free(entry); 915 return 1; 916} 917 918/* 919 * shmem_unuse() search for an eventually swapped out shmem page. 920 */ 921int shmem_unuse(swp_entry_t entry, struct page *page) 922{ 923 struct list_head *p, *next; 924 struct shmem_inode_info *info; 925 int found = 0; 926 927 spin_lock(&shmem_swaplist_lock); 928 list_for_each_safe(p, next, &shmem_swaplist) { 929 info = list_entry(p, struct shmem_inode_info, swaplist); 930 if (!info->swapped) 931 list_del_init(&info->swaplist); 932 else if (shmem_unuse_inode(info, entry, page)) { 933 /* move head to start search for next from here */ 934 list_move_tail(&shmem_swaplist, &info->swaplist); 935 found = 1; 936 break; 937 } 938 } 939 spin_unlock(&shmem_swaplist_lock); 940 return found; 941} 942 943/* 944 * Move the page from the page cache to the swap cache. 945 */ 946static int shmem_writepage(struct page *page, struct writeback_control *wbc) 947{ 948 struct shmem_inode_info *info; 949 swp_entry_t *entry, swap; 950 struct address_space *mapping; 951 unsigned long index; 952 struct inode *inode; 953 954 BUG_ON(!PageLocked(page)); 955 mapping = page->mapping; 956 index = page->index; 957 inode = mapping->host; 958 info = SHMEM_I(inode); 959 if (info->flags & VM_LOCKED) 960 goto redirty; 961 if (!total_swap_pages) 962 goto redirty; 963 964 /* 965 * shmem_backing_dev_info's capabilities prevent regular writeback or 966 * sync from ever calling shmem_writepage; but a stacking filesystem 967 * may use the ->writepage of its underlying filesystem, in which case 968 * tmpfs should write out to swap only in response to memory pressure, 969 * and not for pdflush or sync. However, in those cases, we do still 970 * want to check if there's a redundant swappage to be discarded. 971 */ 972 if (wbc->for_reclaim) 973 swap = get_swap_page(); 974 else 975 swap.val = 0; 976 977 spin_lock(&info->lock); 978 if (index >= info->next_index) { 979 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 980 goto unlock; 981 } 982 entry = shmem_swp_entry(info, index, NULL); 983 if (entry->val) { 984 /* 985 * The more uptodate page coming down from a stacked 986 * writepage should replace our old swappage. 987 */ 988 free_swap_and_cache(*entry); 989 shmem_swp_set(info, entry, 0); 990 } 991 shmem_recalc_inode(inode); 992 993 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 994 remove_from_page_cache(page); 995 shmem_swp_set(info, entry, swap.val); 996 shmem_swp_unmap(entry); 997 spin_unlock(&info->lock); 998 if (list_empty(&info->swaplist)) { 999 spin_lock(&shmem_swaplist_lock); 1000 /* move instead of add in case we're racing */ 1001 list_move_tail(&info->swaplist, &shmem_swaplist); 1002 spin_unlock(&shmem_swaplist_lock); 1003 } 1004 swap_duplicate(swap); 1005 BUG_ON(page_mapped(page)); 1006 page_cache_release(page); /* pagecache ref */ 1007 set_page_dirty(page); 1008 unlock_page(page); 1009 return 0; 1010 } 1011 1012 shmem_swp_unmap(entry); 1013unlock: 1014 spin_unlock(&info->lock); 1015 swap_free(swap); 1016redirty: 1017 set_page_dirty(page); 1018 if (wbc->for_reclaim) 1019 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1020 unlock_page(page); 1021 return 0; 1022} 1023 1024#ifdef CONFIG_NUMA 1025static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 1026{ 1027 char *nodelist = strchr(value, ':'); 1028 int err = 1; 1029 1030 if (nodelist) { 1031 /* NUL-terminate policy string */ 1032 *nodelist++ = '\0'; 1033 if (nodelist_parse(nodelist, *policy_nodes)) 1034 goto out; 1035 if (!nodes_subset(*policy_nodes, node_states[N_HIGH_MEMORY])) 1036 goto out; 1037 } 1038 if (!strcmp(value, "default")) { 1039 *policy = MPOL_DEFAULT; 1040 /* Don't allow a nodelist */ 1041 if (!nodelist) 1042 err = 0; 1043 } else if (!strcmp(value, "prefer")) { 1044 *policy = MPOL_PREFERRED; 1045 /* Insist on a nodelist of one node only */ 1046 if (nodelist) { 1047 char *rest = nodelist; 1048 while (isdigit(*rest)) 1049 rest++; 1050 if (!*rest) 1051 err = 0; 1052 } 1053 } else if (!strcmp(value, "bind")) { 1054 *policy = MPOL_BIND; 1055 /* Insist on a nodelist */ 1056 if (nodelist) 1057 err = 0; 1058 } else if (!strcmp(value, "interleave")) { 1059 *policy = MPOL_INTERLEAVE; 1060 /* 1061 * Default to online nodes with memory if no nodelist 1062 */ 1063 if (!nodelist) 1064 *policy_nodes = node_states[N_HIGH_MEMORY]; 1065 err = 0; 1066 } 1067out: 1068 /* Restore string for error message */ 1069 if (nodelist) 1070 *--nodelist = ':'; 1071 return err; 1072} 1073 1074static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1075 struct shmem_inode_info *info, unsigned long idx) 1076{ 1077 struct vm_area_struct pvma; 1078 struct page *page; 1079 1080 /* Create a pseudo vma that just contains the policy */ 1081 pvma.vm_start = 0; 1082 pvma.vm_pgoff = idx; 1083 pvma.vm_ops = NULL; 1084 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1085 page = swapin_readahead(entry, gfp, &pvma, 0); 1086 mpol_free(pvma.vm_policy); 1087 return page; 1088} 1089 1090static struct page *shmem_alloc_page(gfp_t gfp, 1091 struct shmem_inode_info *info, unsigned long idx) 1092{ 1093 struct vm_area_struct pvma; 1094 struct page *page; 1095 1096 /* Create a pseudo vma that just contains the policy */ 1097 pvma.vm_start = 0; 1098 pvma.vm_pgoff = idx; 1099 pvma.vm_ops = NULL; 1100 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1101 page = alloc_page_vma(gfp, &pvma, 0); 1102 mpol_free(pvma.vm_policy); 1103 return page; 1104} 1105#else 1106static inline int shmem_parse_mpol(char *value, int *policy, 1107 nodemask_t *policy_nodes) 1108{ 1109 return 1; 1110} 1111 1112static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1113 struct shmem_inode_info *info, unsigned long idx) 1114{ 1115 return swapin_readahead(entry, gfp, NULL, 0); 1116} 1117 1118static inline struct page *shmem_alloc_page(gfp_t gfp, 1119 struct shmem_inode_info *info, unsigned long idx) 1120{ 1121 return alloc_page(gfp); 1122} 1123#endif 1124 1125/* 1126 * shmem_getpage - either get the page from swap or allocate a new one 1127 * 1128 * If we allocate a new one we do not mark it dirty. That's up to the 1129 * vm. If we swap it in we mark it dirty since we also free the swap 1130 * entry since a page cannot live in both the swap and page cache 1131 */ 1132static int shmem_getpage(struct inode *inode, unsigned long idx, 1133 struct page **pagep, enum sgp_type sgp, int *type) 1134{ 1135 struct address_space *mapping = inode->i_mapping; 1136 struct shmem_inode_info *info = SHMEM_I(inode); 1137 struct shmem_sb_info *sbinfo; 1138 struct page *filepage = *pagep; 1139 struct page *swappage; 1140 swp_entry_t *entry; 1141 swp_entry_t swap; 1142 gfp_t gfp; 1143 int error; 1144 1145 if (idx >= SHMEM_MAX_INDEX) 1146 return -EFBIG; 1147 1148 if (type) 1149 *type = 0; 1150 1151 /* 1152 * Normally, filepage is NULL on entry, and either found 1153 * uptodate immediately, or allocated and zeroed, or read 1154 * in under swappage, which is then assigned to filepage. 1155 * But shmem_readpage (required for splice) passes in a locked 1156 * filepage, which may be found not uptodate by other callers 1157 * too, and may need to be copied from the swappage read in. 1158 */ 1159repeat: 1160 if (!filepage) 1161 filepage = find_lock_page(mapping, idx); 1162 if (filepage && PageUptodate(filepage)) 1163 goto done; 1164 error = 0; 1165 gfp = mapping_gfp_mask(mapping); 1166 1167 spin_lock(&info->lock); 1168 shmem_recalc_inode(inode); 1169 entry = shmem_swp_alloc(info, idx, sgp); 1170 if (IS_ERR(entry)) { 1171 spin_unlock(&info->lock); 1172 error = PTR_ERR(entry); 1173 goto failed; 1174 } 1175 swap = *entry; 1176 1177 if (swap.val) { 1178 /* Look it up and read it in.. */ 1179 swappage = lookup_swap_cache(swap); 1180 if (!swappage) { 1181 shmem_swp_unmap(entry); 1182 /* here we actually do the io */ 1183 if (type && !(*type & VM_FAULT_MAJOR)) { 1184 __count_vm_event(PGMAJFAULT); 1185 *type |= VM_FAULT_MAJOR; 1186 } 1187 spin_unlock(&info->lock); 1188 swappage = shmem_swapin(swap, gfp, info, idx); 1189 if (!swappage) { 1190 spin_lock(&info->lock); 1191 entry = shmem_swp_alloc(info, idx, sgp); 1192 if (IS_ERR(entry)) 1193 error = PTR_ERR(entry); 1194 else { 1195 if (entry->val == swap.val) 1196 error = -ENOMEM; 1197 shmem_swp_unmap(entry); 1198 } 1199 spin_unlock(&info->lock); 1200 if (error) 1201 goto failed; 1202 goto repeat; 1203 } 1204 wait_on_page_locked(swappage); 1205 page_cache_release(swappage); 1206 goto repeat; 1207 } 1208 1209 /* We have to do this with page locked to prevent races */ 1210 if (TestSetPageLocked(swappage)) { 1211 shmem_swp_unmap(entry); 1212 spin_unlock(&info->lock); 1213 wait_on_page_locked(swappage); 1214 page_cache_release(swappage); 1215 goto repeat; 1216 } 1217 if (PageWriteback(swappage)) { 1218 shmem_swp_unmap(entry); 1219 spin_unlock(&info->lock); 1220 wait_on_page_writeback(swappage); 1221 unlock_page(swappage); 1222 page_cache_release(swappage); 1223 goto repeat; 1224 } 1225 if (!PageUptodate(swappage)) { 1226 shmem_swp_unmap(entry); 1227 spin_unlock(&info->lock); 1228 unlock_page(swappage); 1229 page_cache_release(swappage); 1230 error = -EIO; 1231 goto failed; 1232 } 1233 1234 if (filepage) { 1235 shmem_swp_set(info, entry, 0); 1236 shmem_swp_unmap(entry); 1237 delete_from_swap_cache(swappage); 1238 spin_unlock(&info->lock); 1239 copy_highpage(filepage, swappage); 1240 unlock_page(swappage); 1241 page_cache_release(swappage); 1242 flush_dcache_page(filepage); 1243 SetPageUptodate(filepage); 1244 set_page_dirty(filepage); 1245 swap_free(swap); 1246 } else if (!(error = add_to_page_cache( 1247 swappage, mapping, idx, GFP_ATOMIC))) { 1248 info->flags |= SHMEM_PAGEIN; 1249 shmem_swp_set(info, entry, 0); 1250 shmem_swp_unmap(entry); 1251 delete_from_swap_cache(swappage); 1252 spin_unlock(&info->lock); 1253 filepage = swappage; 1254 set_page_dirty(filepage); 1255 swap_free(swap); 1256 } else { 1257 shmem_swp_unmap(entry); 1258 spin_unlock(&info->lock); 1259 unlock_page(swappage); 1260 page_cache_release(swappage); 1261 if (error == -ENOMEM) { 1262 /* let kswapd refresh zone for GFP_ATOMICs */ 1263 congestion_wait(WRITE, HZ/50); 1264 } 1265 goto repeat; 1266 } 1267 } else if (sgp == SGP_READ && !filepage) { 1268 shmem_swp_unmap(entry); 1269 filepage = find_get_page(mapping, idx); 1270 if (filepage && 1271 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1272 spin_unlock(&info->lock); 1273 wait_on_page_locked(filepage); 1274 page_cache_release(filepage); 1275 filepage = NULL; 1276 goto repeat; 1277 } 1278 spin_unlock(&info->lock); 1279 } else { 1280 shmem_swp_unmap(entry); 1281 sbinfo = SHMEM_SB(inode->i_sb); 1282 if (sbinfo->max_blocks) { 1283 spin_lock(&sbinfo->stat_lock); 1284 if (sbinfo->free_blocks == 0 || 1285 shmem_acct_block(info->flags)) { 1286 spin_unlock(&sbinfo->stat_lock); 1287 spin_unlock(&info->lock); 1288 error = -ENOSPC; 1289 goto failed; 1290 } 1291 sbinfo->free_blocks--; 1292 inode->i_blocks += BLOCKS_PER_PAGE; 1293 spin_unlock(&sbinfo->stat_lock); 1294 } else if (shmem_acct_block(info->flags)) { 1295 spin_unlock(&info->lock); 1296 error = -ENOSPC; 1297 goto failed; 1298 } 1299 1300 if (!filepage) { 1301 spin_unlock(&info->lock); 1302 filepage = shmem_alloc_page(gfp, info, idx); 1303 if (!filepage) { 1304 shmem_unacct_blocks(info->flags, 1); 1305 shmem_free_blocks(inode, 1); 1306 error = -ENOMEM; 1307 goto failed; 1308 } 1309 1310 spin_lock(&info->lock); 1311 entry = shmem_swp_alloc(info, idx, sgp); 1312 if (IS_ERR(entry)) 1313 error = PTR_ERR(entry); 1314 else { 1315 swap = *entry; 1316 shmem_swp_unmap(entry); 1317 } 1318 if (error || swap.val || 0 != add_to_page_cache_lru( 1319 filepage, mapping, idx, GFP_ATOMIC)) { 1320 spin_unlock(&info->lock); 1321 page_cache_release(filepage); 1322 shmem_unacct_blocks(info->flags, 1); 1323 shmem_free_blocks(inode, 1); 1324 filepage = NULL; 1325 if (error) 1326 goto failed; 1327 goto repeat; 1328 } 1329 info->flags |= SHMEM_PAGEIN; 1330 } 1331 1332 info->alloced++; 1333 spin_unlock(&info->lock); 1334 clear_highpage(filepage); 1335 flush_dcache_page(filepage); 1336 SetPageUptodate(filepage); 1337 if (sgp == SGP_DIRTY) 1338 set_page_dirty(filepage); 1339 } 1340done: 1341 *pagep = filepage; 1342 return 0; 1343 1344failed: 1345 if (*pagep != filepage) { 1346 unlock_page(filepage); 1347 page_cache_release(filepage); 1348 } 1349 return error; 1350} 1351 1352static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1353{ 1354 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1355 int error; 1356 int ret; 1357 1358 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1359 return VM_FAULT_SIGBUS; 1360 1361 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1362 if (error) 1363 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1364 1365 mark_page_accessed(vmf->page); 1366 return ret | VM_FAULT_LOCKED; 1367} 1368 1369#ifdef CONFIG_NUMA 1370static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1371{ 1372 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1373 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1374} 1375 1376static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1377 unsigned long addr) 1378{ 1379 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1380 unsigned long idx; 1381 1382 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1383 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1384} 1385#endif 1386 1387int shmem_lock(struct file *file, int lock, struct user_struct *user) 1388{ 1389 struct inode *inode = file->f_path.dentry->d_inode; 1390 struct shmem_inode_info *info = SHMEM_I(inode); 1391 int retval = -ENOMEM; 1392 1393 spin_lock(&info->lock); 1394 if (lock && !(info->flags & VM_LOCKED)) { 1395 if (!user_shm_lock(inode->i_size, user)) 1396 goto out_nomem; 1397 info->flags |= VM_LOCKED; 1398 } 1399 if (!lock && (info->flags & VM_LOCKED) && user) { 1400 user_shm_unlock(inode->i_size, user); 1401 info->flags &= ~VM_LOCKED; 1402 } 1403 retval = 0; 1404out_nomem: 1405 spin_unlock(&info->lock); 1406 return retval; 1407} 1408 1409static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1410{ 1411 file_accessed(file); 1412 vma->vm_ops = &shmem_vm_ops; 1413 vma->vm_flags |= VM_CAN_NONLINEAR; 1414 return 0; 1415} 1416 1417static struct inode * 1418shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1419{ 1420 struct inode *inode; 1421 struct shmem_inode_info *info; 1422 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1423 1424 if (shmem_reserve_inode(sb)) 1425 return NULL; 1426 1427 inode = new_inode(sb); 1428 if (inode) { 1429 inode->i_mode = mode; 1430 inode->i_uid = current->fsuid; 1431 inode->i_gid = current->fsgid; 1432 inode->i_blocks = 0; 1433 inode->i_mapping->a_ops = &shmem_aops; 1434 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1435 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1436 inode->i_generation = get_seconds(); 1437 info = SHMEM_I(inode); 1438 memset(info, 0, (char *)inode - (char *)info); 1439 spin_lock_init(&info->lock); 1440 INIT_LIST_HEAD(&info->swaplist); 1441 1442 switch (mode & S_IFMT) { 1443 default: 1444 inode->i_op = &shmem_special_inode_operations; 1445 init_special_inode(inode, mode, dev); 1446 break; 1447 case S_IFREG: 1448 inode->i_op = &shmem_inode_operations; 1449 inode->i_fop = &shmem_file_operations; 1450 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1451 &sbinfo->policy_nodes); 1452 break; 1453 case S_IFDIR: 1454 inc_nlink(inode); 1455 /* Some things misbehave if size == 0 on a directory */ 1456 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1457 inode->i_op = &shmem_dir_inode_operations; 1458 inode->i_fop = &simple_dir_operations; 1459 break; 1460 case S_IFLNK: 1461 /* 1462 * Must not load anything in the rbtree, 1463 * mpol_free_shared_policy will not be called. 1464 */ 1465 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1466 NULL); 1467 break; 1468 } 1469 } else 1470 shmem_free_inode(sb); 1471 return inode; 1472} 1473 1474#ifdef CONFIG_TMPFS 1475static const struct inode_operations shmem_symlink_inode_operations; 1476static const struct inode_operations shmem_symlink_inline_operations; 1477 1478/* 1479 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1480 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1481 * below the loop driver, in the generic fashion that many filesystems support. 1482 */ 1483static int shmem_readpage(struct file *file, struct page *page) 1484{ 1485 struct inode *inode = page->mapping->host; 1486 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1487 unlock_page(page); 1488 return error; 1489} 1490 1491static int 1492shmem_write_begin(struct file *file, struct address_space *mapping, 1493 loff_t pos, unsigned len, unsigned flags, 1494 struct page **pagep, void **fsdata) 1495{ 1496 struct inode *inode = mapping->host; 1497 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1498 *pagep = NULL; 1499 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1500} 1501 1502static int 1503shmem_write_end(struct file *file, struct address_space *mapping, 1504 loff_t pos, unsigned len, unsigned copied, 1505 struct page *page, void *fsdata) 1506{ 1507 struct inode *inode = mapping->host; 1508 1509 if (pos + copied > inode->i_size) 1510 i_size_write(inode, pos + copied); 1511 1512 unlock_page(page); 1513 set_page_dirty(page); 1514 page_cache_release(page); 1515 1516 return copied; 1517} 1518 1519static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1520{ 1521 struct inode *inode = filp->f_path.dentry->d_inode; 1522 struct address_space *mapping = inode->i_mapping; 1523 unsigned long index, offset; 1524 enum sgp_type sgp = SGP_READ; 1525 1526 /* 1527 * Might this read be for a stacking filesystem? Then when reading 1528 * holes of a sparse file, we actually need to allocate those pages, 1529 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1530 */ 1531 if (segment_eq(get_fs(), KERNEL_DS)) 1532 sgp = SGP_DIRTY; 1533 1534 index = *ppos >> PAGE_CACHE_SHIFT; 1535 offset = *ppos & ~PAGE_CACHE_MASK; 1536 1537 for (;;) { 1538 struct page *page = NULL; 1539 unsigned long end_index, nr, ret; 1540 loff_t i_size = i_size_read(inode); 1541 1542 end_index = i_size >> PAGE_CACHE_SHIFT; 1543 if (index > end_index) 1544 break; 1545 if (index == end_index) { 1546 nr = i_size & ~PAGE_CACHE_MASK; 1547 if (nr <= offset) 1548 break; 1549 } 1550 1551 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1552 if (desc->error) { 1553 if (desc->error == -EINVAL) 1554 desc->error = 0; 1555 break; 1556 } 1557 if (page) 1558 unlock_page(page); 1559 1560 /* 1561 * We must evaluate after, since reads (unlike writes) 1562 * are called without i_mutex protection against truncate 1563 */ 1564 nr = PAGE_CACHE_SIZE; 1565 i_size = i_size_read(inode); 1566 end_index = i_size >> PAGE_CACHE_SHIFT; 1567 if (index == end_index) { 1568 nr = i_size & ~PAGE_CACHE_MASK; 1569 if (nr <= offset) { 1570 if (page) 1571 page_cache_release(page); 1572 break; 1573 } 1574 } 1575 nr -= offset; 1576 1577 if (page) { 1578 /* 1579 * If users can be writing to this page using arbitrary 1580 * virtual addresses, take care about potential aliasing 1581 * before reading the page on the kernel side. 1582 */ 1583 if (mapping_writably_mapped(mapping)) 1584 flush_dcache_page(page); 1585 /* 1586 * Mark the page accessed if we read the beginning. 1587 */ 1588 if (!offset) 1589 mark_page_accessed(page); 1590 } else { 1591 page = ZERO_PAGE(0); 1592 page_cache_get(page); 1593 } 1594 1595 /* 1596 * Ok, we have the page, and it's up-to-date, so 1597 * now we can copy it to user space... 1598 * 1599 * The actor routine returns how many bytes were actually used.. 1600 * NOTE! This may not be the same as how much of a user buffer 1601 * we filled up (we may be padding etc), so we can only update 1602 * "pos" here (the actor routine has to update the user buffer 1603 * pointers and the remaining count). 1604 */ 1605 ret = actor(desc, page, offset, nr); 1606 offset += ret; 1607 index += offset >> PAGE_CACHE_SHIFT; 1608 offset &= ~PAGE_CACHE_MASK; 1609 1610 page_cache_release(page); 1611 if (ret != nr || !desc->count) 1612 break; 1613 1614 cond_resched(); 1615 } 1616 1617 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1618 file_accessed(filp); 1619} 1620 1621static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1622{ 1623 read_descriptor_t desc; 1624 1625 if ((ssize_t) count < 0) 1626 return -EINVAL; 1627 if (!access_ok(VERIFY_WRITE, buf, count)) 1628 return -EFAULT; 1629 if (!count) 1630 return 0; 1631 1632 desc.written = 0; 1633 desc.count = count; 1634 desc.arg.buf = buf; 1635 desc.error = 0; 1636 1637 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1638 if (desc.written) 1639 return desc.written; 1640 return desc.error; 1641} 1642 1643static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1644{ 1645 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1646 1647 buf->f_type = TMPFS_MAGIC; 1648 buf->f_bsize = PAGE_CACHE_SIZE; 1649 buf->f_namelen = NAME_MAX; 1650 spin_lock(&sbinfo->stat_lock); 1651 if (sbinfo->max_blocks) { 1652 buf->f_blocks = sbinfo->max_blocks; 1653 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1654 } 1655 if (sbinfo->max_inodes) { 1656 buf->f_files = sbinfo->max_inodes; 1657 buf->f_ffree = sbinfo->free_inodes; 1658 } 1659 /* else leave those fields 0 like simple_statfs */ 1660 spin_unlock(&sbinfo->stat_lock); 1661 return 0; 1662} 1663 1664/* 1665 * File creation. Allocate an inode, and we're done.. 1666 */ 1667static int 1668shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1669{ 1670 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1671 int error = -ENOSPC; 1672 1673 if (inode) { 1674 error = security_inode_init_security(inode, dir, NULL, NULL, 1675 NULL); 1676 if (error) { 1677 if (error != -EOPNOTSUPP) { 1678 iput(inode); 1679 return error; 1680 } 1681 } 1682 error = shmem_acl_init(inode, dir); 1683 if (error) { 1684 iput(inode); 1685 return error; 1686 } 1687 if (dir->i_mode & S_ISGID) { 1688 inode->i_gid = dir->i_gid; 1689 if (S_ISDIR(mode)) 1690 inode->i_mode |= S_ISGID; 1691 } 1692 dir->i_size += BOGO_DIRENT_SIZE; 1693 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1694 d_instantiate(dentry, inode); 1695 dget(dentry); /* Extra count - pin the dentry in core */ 1696 } 1697 return error; 1698} 1699 1700static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1701{ 1702 int error; 1703 1704 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1705 return error; 1706 inc_nlink(dir); 1707 return 0; 1708} 1709 1710static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1711 struct nameidata *nd) 1712{ 1713 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1714} 1715 1716/* 1717 * Link a file.. 1718 */ 1719static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1720{ 1721 struct inode *inode = old_dentry->d_inode; 1722 int ret; 1723 1724 /* 1725 * No ordinary (disk based) filesystem counts links as inodes; 1726 * but each new link needs a new dentry, pinning lowmem, and 1727 * tmpfs dentries cannot be pruned until they are unlinked. 1728 */ 1729 ret = shmem_reserve_inode(inode->i_sb); 1730 if (ret) 1731 goto out; 1732 1733 dir->i_size += BOGO_DIRENT_SIZE; 1734 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1735 inc_nlink(inode); 1736 atomic_inc(&inode->i_count); /* New dentry reference */ 1737 dget(dentry); /* Extra pinning count for the created dentry */ 1738 d_instantiate(dentry, inode); 1739out: 1740 return ret; 1741} 1742 1743static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1744{ 1745 struct inode *inode = dentry->d_inode; 1746 1747 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1748 shmem_free_inode(inode->i_sb); 1749 1750 dir->i_size -= BOGO_DIRENT_SIZE; 1751 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1752 drop_nlink(inode); 1753 dput(dentry); /* Undo the count from "create" - this does all the work */ 1754 return 0; 1755} 1756 1757static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1758{ 1759 if (!simple_empty(dentry)) 1760 return -ENOTEMPTY; 1761 1762 drop_nlink(dentry->d_inode); 1763 drop_nlink(dir); 1764 return shmem_unlink(dir, dentry); 1765} 1766 1767/* 1768 * The VFS layer already does all the dentry stuff for rename, 1769 * we just have to decrement the usage count for the target if 1770 * it exists so that the VFS layer correctly free's it when it 1771 * gets overwritten. 1772 */ 1773static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1774{ 1775 struct inode *inode = old_dentry->d_inode; 1776 int they_are_dirs = S_ISDIR(inode->i_mode); 1777 1778 if (!simple_empty(new_dentry)) 1779 return -ENOTEMPTY; 1780 1781 if (new_dentry->d_inode) { 1782 (void) shmem_unlink(new_dir, new_dentry); 1783 if (they_are_dirs) 1784 drop_nlink(old_dir); 1785 } else if (they_are_dirs) { 1786 drop_nlink(old_dir); 1787 inc_nlink(new_dir); 1788 } 1789 1790 old_dir->i_size -= BOGO_DIRENT_SIZE; 1791 new_dir->i_size += BOGO_DIRENT_SIZE; 1792 old_dir->i_ctime = old_dir->i_mtime = 1793 new_dir->i_ctime = new_dir->i_mtime = 1794 inode->i_ctime = CURRENT_TIME; 1795 return 0; 1796} 1797 1798static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1799{ 1800 int error; 1801 int len; 1802 struct inode *inode; 1803 struct page *page = NULL; 1804 char *kaddr; 1805 struct shmem_inode_info *info; 1806 1807 len = strlen(symname) + 1; 1808 if (len > PAGE_CACHE_SIZE) 1809 return -ENAMETOOLONG; 1810 1811 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1812 if (!inode) 1813 return -ENOSPC; 1814 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 error = 0; 1823 } 1824 1825 info = SHMEM_I(inode); 1826 inode->i_size = len-1; 1827 if (len <= (char *)inode - (char *)info) { 1828 /* do it inline */ 1829 memcpy(info, symname, len); 1830 inode->i_op = &shmem_symlink_inline_operations; 1831 } else { 1832 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1833 if (error) { 1834 iput(inode); 1835 return error; 1836 } 1837 unlock_page(page); 1838 inode->i_op = &shmem_symlink_inode_operations; 1839 kaddr = kmap_atomic(page, KM_USER0); 1840 memcpy(kaddr, symname, len); 1841 kunmap_atomic(kaddr, KM_USER0); 1842 set_page_dirty(page); 1843 page_cache_release(page); 1844 } 1845 if (dir->i_mode & S_ISGID) 1846 inode->i_gid = dir->i_gid; 1847 dir->i_size += BOGO_DIRENT_SIZE; 1848 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1849 d_instantiate(dentry, inode); 1850 dget(dentry); 1851 return 0; 1852} 1853 1854static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1855{ 1856 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1857 return NULL; 1858} 1859 1860static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1861{ 1862 struct page *page = NULL; 1863 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1864 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1865 if (page) 1866 unlock_page(page); 1867 return page; 1868} 1869 1870static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1871{ 1872 if (!IS_ERR(nd_get_link(nd))) { 1873 struct page *page = cookie; 1874 kunmap(page); 1875 mark_page_accessed(page); 1876 page_cache_release(page); 1877 } 1878} 1879 1880static const struct inode_operations shmem_symlink_inline_operations = { 1881 .readlink = generic_readlink, 1882 .follow_link = shmem_follow_link_inline, 1883}; 1884 1885static const struct inode_operations shmem_symlink_inode_operations = { 1886 .truncate = shmem_truncate, 1887 .readlink = generic_readlink, 1888 .follow_link = shmem_follow_link, 1889 .put_link = shmem_put_link, 1890}; 1891 1892#ifdef CONFIG_TMPFS_POSIX_ACL 1893/** 1894 * Superblocks without xattr inode operations will get security.* xattr 1895 * support from the VFS "for free". As soon as we have any other xattrs 1896 * like ACLs, we also need to implement the security.* handlers at 1897 * filesystem level, though. 1898 */ 1899 1900static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1901 size_t list_len, const char *name, 1902 size_t name_len) 1903{ 1904 return security_inode_listsecurity(inode, list, list_len); 1905} 1906 1907static int shmem_xattr_security_get(struct inode *inode, const char *name, 1908 void *buffer, size_t size) 1909{ 1910 if (strcmp(name, "") == 0) 1911 return -EINVAL; 1912 return security_inode_getsecurity(inode, name, buffer, size, 1913 -EOPNOTSUPP); 1914} 1915 1916static int shmem_xattr_security_set(struct inode *inode, const char *name, 1917 const void *value, size_t size, int flags) 1918{ 1919 if (strcmp(name, "") == 0) 1920 return -EINVAL; 1921 return security_inode_setsecurity(inode, name, value, size, flags); 1922} 1923 1924static struct xattr_handler shmem_xattr_security_handler = { 1925 .prefix = XATTR_SECURITY_PREFIX, 1926 .list = shmem_xattr_security_list, 1927 .get = shmem_xattr_security_get, 1928 .set = shmem_xattr_security_set, 1929}; 1930 1931static struct xattr_handler *shmem_xattr_handlers[] = { 1932 &shmem_xattr_acl_access_handler, 1933 &shmem_xattr_acl_default_handler, 1934 &shmem_xattr_security_handler, 1935 NULL 1936}; 1937#endif 1938 1939static struct dentry *shmem_get_parent(struct dentry *child) 1940{ 1941 return ERR_PTR(-ESTALE); 1942} 1943 1944static int shmem_match(struct inode *ino, void *vfh) 1945{ 1946 __u32 *fh = vfh; 1947 __u64 inum = fh[2]; 1948 inum = (inum << 32) | fh[1]; 1949 return ino->i_ino == inum && fh[0] == ino->i_generation; 1950} 1951 1952static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 1953 struct fid *fid, int fh_len, int fh_type) 1954{ 1955 struct inode *inode; 1956 struct dentry *dentry = NULL; 1957 u64 inum = fid->raw[2]; 1958 inum = (inum << 32) | fid->raw[1]; 1959 1960 if (fh_len < 3) 1961 return NULL; 1962 1963 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 1964 shmem_match, fid->raw); 1965 if (inode) { 1966 dentry = d_find_alias(inode); 1967 iput(inode); 1968 } 1969 1970 return dentry; 1971} 1972 1973static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 1974 int connectable) 1975{ 1976 struct inode *inode = dentry->d_inode; 1977 1978 if (*len < 3) 1979 return 255; 1980 1981 if (hlist_unhashed(&inode->i_hash)) { 1982 /* Unfortunately insert_inode_hash is not idempotent, 1983 * so as we hash inodes here rather than at creation 1984 * time, we need a lock to ensure we only try 1985 * to do it once 1986 */ 1987 static DEFINE_SPINLOCK(lock); 1988 spin_lock(&lock); 1989 if (hlist_unhashed(&inode->i_hash)) 1990 __insert_inode_hash(inode, 1991 inode->i_ino + inode->i_generation); 1992 spin_unlock(&lock); 1993 } 1994 1995 fh[0] = inode->i_generation; 1996 fh[1] = inode->i_ino; 1997 fh[2] = ((__u64)inode->i_ino) >> 32; 1998 1999 *len = 3; 2000 return 1; 2001} 2002 2003static const struct export_operations shmem_export_ops = { 2004 .get_parent = shmem_get_parent, 2005 .encode_fh = shmem_encode_fh, 2006 .fh_to_dentry = shmem_fh_to_dentry, 2007}; 2008 2009static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2010 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2011 int *policy, nodemask_t *policy_nodes) 2012{ 2013 char *this_char, *value, *rest; 2014 2015 while (options != NULL) { 2016 this_char = options; 2017 for (;;) { 2018 /* 2019 * NUL-terminate this option: unfortunately, 2020 * mount options form a comma-separated list, 2021 * but mpol's nodelist may also contain commas. 2022 */ 2023 options = strchr(options, ','); 2024 if (options == NULL) 2025 break; 2026 options++; 2027 if (!isdigit(*options)) { 2028 options[-1] = '\0'; 2029 break; 2030 } 2031 } 2032 if (!*this_char) 2033 continue; 2034 if ((value = strchr(this_char,'=')) != NULL) { 2035 *value++ = 0; 2036 } else { 2037 printk(KERN_ERR 2038 "tmpfs: No value for mount option '%s'\n", 2039 this_char); 2040 return 1; 2041 } 2042 2043 if (!strcmp(this_char,"size")) { 2044 unsigned long long size; 2045 size = memparse(value,&rest); 2046 if (*rest == '%') { 2047 size <<= PAGE_SHIFT; 2048 size *= totalram_pages; 2049 do_div(size, 100); 2050 rest++; 2051 } 2052 if (*rest) 2053 goto bad_val; 2054 *blocks = DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2055 } else if (!strcmp(this_char,"nr_blocks")) { 2056 *blocks = memparse(value,&rest); 2057 if (*rest) 2058 goto bad_val; 2059 } else if (!strcmp(this_char,"nr_inodes")) { 2060 *inodes = memparse(value,&rest); 2061 if (*rest) 2062 goto bad_val; 2063 } else if (!strcmp(this_char,"mode")) { 2064 if (!mode) 2065 continue; 2066 *mode = simple_strtoul(value,&rest,8); 2067 if (*rest) 2068 goto bad_val; 2069 } else if (!strcmp(this_char,"uid")) { 2070 if (!uid) 2071 continue; 2072 *uid = simple_strtoul(value,&rest,0); 2073 if (*rest) 2074 goto bad_val; 2075 } else if (!strcmp(this_char,"gid")) { 2076 if (!gid) 2077 continue; 2078 *gid = simple_strtoul(value,&rest,0); 2079 if (*rest) 2080 goto bad_val; 2081 } else if (!strcmp(this_char,"mpol")) { 2082 if (shmem_parse_mpol(value,policy,policy_nodes)) 2083 goto bad_val; 2084 } else { 2085 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2086 this_char); 2087 return 1; 2088 } 2089 } 2090 return 0; 2091 2092bad_val: 2093 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2094 value, this_char); 2095 return 1; 2096 2097} 2098 2099static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2100{ 2101 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2102 unsigned long max_blocks = sbinfo->max_blocks; 2103 unsigned long max_inodes = sbinfo->max_inodes; 2104 int policy = sbinfo->policy; 2105 nodemask_t policy_nodes = sbinfo->policy_nodes; 2106 unsigned long blocks; 2107 unsigned long inodes; 2108 int error = -EINVAL; 2109 2110 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2111 &max_inodes, &policy, &policy_nodes)) 2112 return error; 2113 2114 spin_lock(&sbinfo->stat_lock); 2115 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2116 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2117 if (max_blocks < blocks) 2118 goto out; 2119 if (max_inodes < inodes) 2120 goto out; 2121 /* 2122 * Those tests also disallow limited->unlimited while any are in 2123 * use, so i_blocks will always be zero when max_blocks is zero; 2124 * but we must separately disallow unlimited->limited, because 2125 * in that case we have no record of how much is already in use. 2126 */ 2127 if (max_blocks && !sbinfo->max_blocks) 2128 goto out; 2129 if (max_inodes && !sbinfo->max_inodes) 2130 goto out; 2131 2132 error = 0; 2133 sbinfo->max_blocks = max_blocks; 2134 sbinfo->free_blocks = max_blocks - blocks; 2135 sbinfo->max_inodes = max_inodes; 2136 sbinfo->free_inodes = max_inodes - inodes; 2137 sbinfo->policy = policy; 2138 sbinfo->policy_nodes = policy_nodes; 2139out: 2140 spin_unlock(&sbinfo->stat_lock); 2141 return error; 2142} 2143#endif 2144 2145static void shmem_put_super(struct super_block *sb) 2146{ 2147 kfree(sb->s_fs_info); 2148 sb->s_fs_info = NULL; 2149} 2150 2151static int shmem_fill_super(struct super_block *sb, 2152 void *data, int silent) 2153{ 2154 struct inode *inode; 2155 struct dentry *root; 2156 int mode = S_IRWXUGO | S_ISVTX; 2157 uid_t uid = current->fsuid; 2158 gid_t gid = current->fsgid; 2159 int err = -ENOMEM; 2160 struct shmem_sb_info *sbinfo; 2161 unsigned long blocks = 0; 2162 unsigned long inodes = 0; 2163 int policy = MPOL_DEFAULT; 2164 nodemask_t policy_nodes = node_states[N_HIGH_MEMORY]; 2165 2166#ifdef CONFIG_TMPFS 2167 /* 2168 * Per default we only allow half of the physical ram per 2169 * tmpfs instance, limiting inodes to one per page of lowmem; 2170 * but the internal instance is left unlimited. 2171 */ 2172 if (!(sb->s_flags & MS_NOUSER)) { 2173 blocks = totalram_pages / 2; 2174 inodes = totalram_pages - totalhigh_pages; 2175 if (inodes > blocks) 2176 inodes = blocks; 2177 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2178 &inodes, &policy, &policy_nodes)) 2179 return -EINVAL; 2180 } 2181 sb->s_export_op = &shmem_export_ops; 2182#else 2183 sb->s_flags |= MS_NOUSER; 2184#endif 2185 2186 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2187 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2188 L1_CACHE_BYTES), GFP_KERNEL); 2189 if (!sbinfo) 2190 return -ENOMEM; 2191 2192 spin_lock_init(&sbinfo->stat_lock); 2193 sbinfo->max_blocks = blocks; 2194 sbinfo->free_blocks = blocks; 2195 sbinfo->max_inodes = inodes; 2196 sbinfo->free_inodes = inodes; 2197 sbinfo->policy = policy; 2198 sbinfo->policy_nodes = policy_nodes; 2199 2200 sb->s_fs_info = sbinfo; 2201 sb->s_maxbytes = SHMEM_MAX_BYTES; 2202 sb->s_blocksize = PAGE_CACHE_SIZE; 2203 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2204 sb->s_magic = TMPFS_MAGIC; 2205 sb->s_op = &shmem_ops; 2206 sb->s_time_gran = 1; 2207#ifdef CONFIG_TMPFS_POSIX_ACL 2208 sb->s_xattr = shmem_xattr_handlers; 2209 sb->s_flags |= MS_POSIXACL; 2210#endif 2211 2212 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2213 if (!inode) 2214 goto failed; 2215 inode->i_uid = uid; 2216 inode->i_gid = gid; 2217 root = d_alloc_root(inode); 2218 if (!root) 2219 goto failed_iput; 2220 sb->s_root = root; 2221 return 0; 2222 2223failed_iput: 2224 iput(inode); 2225failed: 2226 shmem_put_super(sb); 2227 return err; 2228} 2229 2230static struct kmem_cache *shmem_inode_cachep; 2231 2232static struct inode *shmem_alloc_inode(struct super_block *sb) 2233{ 2234 struct shmem_inode_info *p; 2235 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2236 if (!p) 2237 return NULL; 2238 return &p->vfs_inode; 2239} 2240 2241static void shmem_destroy_inode(struct inode *inode) 2242{ 2243 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2244 /* only struct inode is valid if it's an inline symlink */ 2245 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2246 } 2247 shmem_acl_destroy_inode(inode); 2248 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2249} 2250 2251static void init_once(struct kmem_cache *cachep, void *foo) 2252{ 2253 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2254 2255 inode_init_once(&p->vfs_inode); 2256#ifdef CONFIG_TMPFS_POSIX_ACL 2257 p->i_acl = NULL; 2258 p->i_default_acl = NULL; 2259#endif 2260} 2261 2262static int init_inodecache(void) 2263{ 2264 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2265 sizeof(struct shmem_inode_info), 2266 0, SLAB_PANIC, init_once); 2267 return 0; 2268} 2269 2270static void destroy_inodecache(void) 2271{ 2272 kmem_cache_destroy(shmem_inode_cachep); 2273} 2274 2275static const struct address_space_operations shmem_aops = { 2276 .writepage = shmem_writepage, 2277 .set_page_dirty = __set_page_dirty_no_writeback, 2278#ifdef CONFIG_TMPFS 2279 .readpage = shmem_readpage, 2280 .write_begin = shmem_write_begin, 2281 .write_end = shmem_write_end, 2282#endif 2283 .migratepage = migrate_page, 2284}; 2285 2286static const struct file_operations shmem_file_operations = { 2287 .mmap = shmem_mmap, 2288#ifdef CONFIG_TMPFS 2289 .llseek = generic_file_llseek, 2290 .read = shmem_file_read, 2291 .write = do_sync_write, 2292 .aio_write = generic_file_aio_write, 2293 .fsync = simple_sync_file, 2294 .splice_read = generic_file_splice_read, 2295 .splice_write = generic_file_splice_write, 2296#endif 2297}; 2298 2299static const struct inode_operations shmem_inode_operations = { 2300 .truncate = shmem_truncate, 2301 .setattr = shmem_notify_change, 2302 .truncate_range = shmem_truncate_range, 2303#ifdef CONFIG_TMPFS_POSIX_ACL 2304 .setxattr = generic_setxattr, 2305 .getxattr = generic_getxattr, 2306 .listxattr = generic_listxattr, 2307 .removexattr = generic_removexattr, 2308 .permission = shmem_permission, 2309#endif 2310 2311}; 2312 2313static const struct inode_operations shmem_dir_inode_operations = { 2314#ifdef CONFIG_TMPFS 2315 .create = shmem_create, 2316 .lookup = simple_lookup, 2317 .link = shmem_link, 2318 .unlink = shmem_unlink, 2319 .symlink = shmem_symlink, 2320 .mkdir = shmem_mkdir, 2321 .rmdir = shmem_rmdir, 2322 .mknod = shmem_mknod, 2323 .rename = shmem_rename, 2324#endif 2325#ifdef CONFIG_TMPFS_POSIX_ACL 2326 .setattr = shmem_notify_change, 2327 .setxattr = generic_setxattr, 2328 .getxattr = generic_getxattr, 2329 .listxattr = generic_listxattr, 2330 .removexattr = generic_removexattr, 2331 .permission = shmem_permission, 2332#endif 2333}; 2334 2335static const struct inode_operations shmem_special_inode_operations = { 2336#ifdef CONFIG_TMPFS_POSIX_ACL 2337 .setattr = shmem_notify_change, 2338 .setxattr = generic_setxattr, 2339 .getxattr = generic_getxattr, 2340 .listxattr = generic_listxattr, 2341 .removexattr = generic_removexattr, 2342 .permission = shmem_permission, 2343#endif 2344}; 2345 2346static const struct super_operations shmem_ops = { 2347 .alloc_inode = shmem_alloc_inode, 2348 .destroy_inode = shmem_destroy_inode, 2349#ifdef CONFIG_TMPFS 2350 .statfs = shmem_statfs, 2351 .remount_fs = shmem_remount_fs, 2352#endif 2353 .delete_inode = shmem_delete_inode, 2354 .drop_inode = generic_delete_inode, 2355 .put_super = shmem_put_super, 2356}; 2357 2358static struct vm_operations_struct shmem_vm_ops = { 2359 .fault = shmem_fault, 2360#ifdef CONFIG_NUMA 2361 .set_policy = shmem_set_policy, 2362 .get_policy = shmem_get_policy, 2363#endif 2364}; 2365 2366 2367static int shmem_get_sb(struct file_system_type *fs_type, 2368 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2369{ 2370 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2371} 2372 2373static struct file_system_type tmpfs_fs_type = { 2374 .owner = THIS_MODULE, 2375 .name = "tmpfs", 2376 .get_sb = shmem_get_sb, 2377 .kill_sb = kill_litter_super, 2378}; 2379static struct vfsmount *shm_mnt; 2380 2381static int __init init_tmpfs(void) 2382{ 2383 int error; 2384 2385 error = bdi_init(&shmem_backing_dev_info); 2386 if (error) 2387 goto out4; 2388 2389 error = init_inodecache(); 2390 if (error) 2391 goto out3; 2392 2393 error = register_filesystem(&tmpfs_fs_type); 2394 if (error) { 2395 printk(KERN_ERR "Could not register tmpfs\n"); 2396 goto out2; 2397 } 2398 2399 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2400 tmpfs_fs_type.name, NULL); 2401 if (IS_ERR(shm_mnt)) { 2402 error = PTR_ERR(shm_mnt); 2403 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2404 goto out1; 2405 } 2406 return 0; 2407 2408out1: 2409 unregister_filesystem(&tmpfs_fs_type); 2410out2: 2411 destroy_inodecache(); 2412out3: 2413 bdi_destroy(&shmem_backing_dev_info); 2414out4: 2415 shm_mnt = ERR_PTR(error); 2416 return error; 2417} 2418module_init(init_tmpfs) 2419 2420/* 2421 * shmem_file_setup - get an unlinked file living in tmpfs 2422 * 2423 * @name: name for dentry (to be seen in /proc/<pid>/maps 2424 * @size: size to be set for the file 2425 * 2426 */ 2427struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2428{ 2429 int error; 2430 struct file *file; 2431 struct inode *inode; 2432 struct dentry *dentry, *root; 2433 struct qstr this; 2434 2435 if (IS_ERR(shm_mnt)) 2436 return (void *)shm_mnt; 2437 2438 if (size < 0 || size > SHMEM_MAX_BYTES) 2439 return ERR_PTR(-EINVAL); 2440 2441 if (shmem_acct_size(flags, size)) 2442 return ERR_PTR(-ENOMEM); 2443 2444 error = -ENOMEM; 2445 this.name = name; 2446 this.len = strlen(name); 2447 this.hash = 0; /* will go */ 2448 root = shm_mnt->mnt_root; 2449 dentry = d_alloc(root, &this); 2450 if (!dentry) 2451 goto put_memory; 2452 2453 error = -ENFILE; 2454 file = get_empty_filp(); 2455 if (!file) 2456 goto put_dentry; 2457 2458 error = -ENOSPC; 2459 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2460 if (!inode) 2461 goto close_file; 2462 2463 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2464 d_instantiate(dentry, inode); 2465 inode->i_size = size; 2466 inode->i_nlink = 0; /* It is unlinked */ 2467 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ, 2468 &shmem_file_operations); 2469 return file; 2470 2471close_file: 2472 put_filp(file); 2473put_dentry: 2474 dput(dentry); 2475put_memory: 2476 shmem_unacct_size(flags, size); 2477 return ERR_PTR(error); 2478} 2479 2480/* 2481 * shmem_zero_setup - setup a shared anonymous mapping 2482 * 2483 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2484 */ 2485int shmem_zero_setup(struct vm_area_struct *vma) 2486{ 2487 struct file *file; 2488 loff_t size = vma->vm_end - vma->vm_start; 2489 2490 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2491 if (IS_ERR(file)) 2492 return PTR_ERR(file); 2493 2494 if (vma->vm_file) 2495 fput(vma->vm_file); 2496 vma->vm_file = file; 2497 vma->vm_ops = &shmem_vm_ops; 2498 return 0; 2499} 2500