shmem.c revision b409f9fcf04692c0f603d28c73d2e3dfed27bf54
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 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 goto found; 843 if (!info->i_indirect) 844 goto lost2; 845 846 dir = shmem_dir_map(info->i_indirect); 847 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 848 849 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 850 if (unlikely(idx == stage)) { 851 shmem_dir_unmap(dir-1); 852 if (cond_resched_lock(&info->lock)) { 853 /* check it has not been truncated */ 854 if (limit > info->next_index) { 855 limit = info->next_index; 856 if (idx >= limit) 857 goto lost2; 858 } 859 } 860 dir = shmem_dir_map(info->i_indirect) + 861 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 862 while (!*dir) { 863 dir++; 864 idx += ENTRIES_PER_PAGEPAGE; 865 if (idx >= limit) 866 goto lost1; 867 } 868 stage = idx + ENTRIES_PER_PAGEPAGE; 869 subdir = *dir; 870 shmem_dir_unmap(dir); 871 dir = shmem_dir_map(subdir); 872 } 873 subdir = *dir; 874 if (subdir && page_private(subdir)) { 875 ptr = shmem_swp_map(subdir); 876 size = limit - idx; 877 if (size > ENTRIES_PER_PAGE) 878 size = ENTRIES_PER_PAGE; 879 offset = shmem_find_swp(entry, ptr, ptr+size); 880 shmem_swp_unmap(ptr); 881 if (offset >= 0) { 882 shmem_dir_unmap(dir); 883 goto found; 884 } 885 } 886 } 887lost1: 888 shmem_dir_unmap(dir-1); 889lost2: 890 spin_unlock(&info->lock); 891 return 0; 892found: 893 idx += offset; 894 inode = igrab(&info->vfs_inode); 895 spin_unlock(&info->lock); 896 897 /* move head to start search for next from here */ 898 list_move_tail(&shmem_swaplist, &info->swaplist); 899 mutex_unlock(&shmem_swaplist_mutex); 900 901 error = 1; 902 if (!inode) 903 goto out; 904 error = radix_tree_preload(GFP_KERNEL); 905 if (error) 906 goto out; 907 error = 1; 908 909 spin_lock(&info->lock); 910 ptr = shmem_swp_entry(info, idx, NULL); 911 if (ptr && ptr->val == entry.val) 912 error = add_to_page_cache(page, inode->i_mapping, 913 idx, GFP_NOWAIT); 914 if (error == -EEXIST) { 915 struct page *filepage = find_get_page(inode->i_mapping, idx); 916 error = 1; 917 if (filepage) { 918 /* 919 * There might be a more uptodate page coming down 920 * from a stacked writepage: forget our swappage if so. 921 */ 922 if (PageUptodate(filepage)) 923 error = 0; 924 page_cache_release(filepage); 925 } 926 } 927 if (!error) { 928 delete_from_swap_cache(page); 929 set_page_dirty(page); 930 info->flags |= SHMEM_PAGEIN; 931 shmem_swp_set(info, ptr, 0); 932 swap_free(entry); 933 error = 1; /* not an error, but entry was found */ 934 } 935 if (ptr) 936 shmem_swp_unmap(ptr); 937 spin_unlock(&info->lock); 938 radix_tree_preload_end(); 939out: 940 unlock_page(page); 941 page_cache_release(page); 942 iput(inode); /* allows for NULL */ 943 return error; 944} 945 946/* 947 * shmem_unuse() search for an eventually swapped out shmem page. 948 */ 949int shmem_unuse(swp_entry_t entry, struct page *page) 950{ 951 struct list_head *p, *next; 952 struct shmem_inode_info *info; 953 int found = 0; 954 955 mutex_lock(&shmem_swaplist_mutex); 956 list_for_each_safe(p, next, &shmem_swaplist) { 957 info = list_entry(p, struct shmem_inode_info, swaplist); 958 if (info->swapped) 959 found = shmem_unuse_inode(info, entry, page); 960 else 961 list_del_init(&info->swaplist); 962 cond_resched(); 963 if (found) 964 goto out; 965 } 966 mutex_unlock(&shmem_swaplist_mutex); 967out: return found; /* 0 or 1 or -ENOMEM */ 968} 969 970/* 971 * Move the page from the page cache to the swap cache. 972 */ 973static int shmem_writepage(struct page *page, struct writeback_control *wbc) 974{ 975 struct shmem_inode_info *info; 976 swp_entry_t *entry, swap; 977 struct address_space *mapping; 978 unsigned long index; 979 struct inode *inode; 980 981 BUG_ON(!PageLocked(page)); 982 mapping = page->mapping; 983 index = page->index; 984 inode = mapping->host; 985 info = SHMEM_I(inode); 986 if (info->flags & VM_LOCKED) 987 goto redirty; 988 if (!total_swap_pages) 989 goto redirty; 990 991 /* 992 * shmem_backing_dev_info's capabilities prevent regular writeback or 993 * sync from ever calling shmem_writepage; but a stacking filesystem 994 * may use the ->writepage of its underlying filesystem, in which case 995 * tmpfs should write out to swap only in response to memory pressure, 996 * and not for pdflush or sync. However, in those cases, we do still 997 * want to check if there's a redundant swappage to be discarded. 998 */ 999 if (wbc->for_reclaim) 1000 swap = get_swap_page(); 1001 else 1002 swap.val = 0; 1003 1004 spin_lock(&info->lock); 1005 if (index >= info->next_index) { 1006 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1007 goto unlock; 1008 } 1009 entry = shmem_swp_entry(info, index, NULL); 1010 if (entry->val) { 1011 /* 1012 * The more uptodate page coming down from a stacked 1013 * writepage should replace our old swappage. 1014 */ 1015 free_swap_and_cache(*entry); 1016 shmem_swp_set(info, entry, 0); 1017 } 1018 shmem_recalc_inode(inode); 1019 1020 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1021 remove_from_page_cache(page); 1022 shmem_swp_set(info, entry, swap.val); 1023 shmem_swp_unmap(entry); 1024 spin_unlock(&info->lock); 1025 if (list_empty(&info->swaplist)) { 1026 mutex_lock(&shmem_swaplist_mutex); 1027 /* move instead of add in case we're racing */ 1028 list_move_tail(&info->swaplist, &shmem_swaplist); 1029 mutex_unlock(&shmem_swaplist_mutex); 1030 } 1031 swap_duplicate(swap); 1032 BUG_ON(page_mapped(page)); 1033 page_cache_release(page); /* pagecache ref */ 1034 set_page_dirty(page); 1035 unlock_page(page); 1036 return 0; 1037 } 1038 1039 shmem_swp_unmap(entry); 1040unlock: 1041 spin_unlock(&info->lock); 1042 swap_free(swap); 1043redirty: 1044 set_page_dirty(page); 1045 if (wbc->for_reclaim) 1046 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1047 unlock_page(page); 1048 return 0; 1049} 1050 1051#ifdef CONFIG_NUMA 1052static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 1053{ 1054 char *nodelist = strchr(value, ':'); 1055 int err = 1; 1056 1057 if (nodelist) { 1058 /* NUL-terminate policy string */ 1059 *nodelist++ = '\0'; 1060 if (nodelist_parse(nodelist, *policy_nodes)) 1061 goto out; 1062 if (!nodes_subset(*policy_nodes, node_states[N_HIGH_MEMORY])) 1063 goto out; 1064 } 1065 if (!strcmp(value, "default")) { 1066 *policy = MPOL_DEFAULT; 1067 /* Don't allow a nodelist */ 1068 if (!nodelist) 1069 err = 0; 1070 } else if (!strcmp(value, "prefer")) { 1071 *policy = MPOL_PREFERRED; 1072 /* Insist on a nodelist of one node only */ 1073 if (nodelist) { 1074 char *rest = nodelist; 1075 while (isdigit(*rest)) 1076 rest++; 1077 if (!*rest) 1078 err = 0; 1079 } 1080 } else if (!strcmp(value, "bind")) { 1081 *policy = MPOL_BIND; 1082 /* Insist on a nodelist */ 1083 if (nodelist) 1084 err = 0; 1085 } else if (!strcmp(value, "interleave")) { 1086 *policy = MPOL_INTERLEAVE; 1087 /* 1088 * Default to online nodes with memory if no nodelist 1089 */ 1090 if (!nodelist) 1091 *policy_nodes = node_states[N_HIGH_MEMORY]; 1092 err = 0; 1093 } 1094out: 1095 /* Restore string for error message */ 1096 if (nodelist) 1097 *--nodelist = ':'; 1098 return err; 1099} 1100 1101static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1102 struct shmem_inode_info *info, unsigned long idx) 1103{ 1104 struct vm_area_struct pvma; 1105 struct page *page; 1106 1107 /* Create a pseudo vma that just contains the policy */ 1108 pvma.vm_start = 0; 1109 pvma.vm_pgoff = idx; 1110 pvma.vm_ops = NULL; 1111 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1112 page = swapin_readahead(entry, gfp, &pvma, 0); 1113 mpol_free(pvma.vm_policy); 1114 return page; 1115} 1116 1117static struct page *shmem_alloc_page(gfp_t gfp, 1118 struct shmem_inode_info *info, unsigned long idx) 1119{ 1120 struct vm_area_struct pvma; 1121 struct page *page; 1122 1123 /* Create a pseudo vma that just contains the policy */ 1124 pvma.vm_start = 0; 1125 pvma.vm_pgoff = idx; 1126 pvma.vm_ops = NULL; 1127 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1128 page = alloc_page_vma(gfp, &pvma, 0); 1129 mpol_free(pvma.vm_policy); 1130 return page; 1131} 1132#else 1133static inline int shmem_parse_mpol(char *value, int *policy, 1134 nodemask_t *policy_nodes) 1135{ 1136 return 1; 1137} 1138 1139static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1140 struct shmem_inode_info *info, unsigned long idx) 1141{ 1142 return swapin_readahead(entry, gfp, NULL, 0); 1143} 1144 1145static inline struct page *shmem_alloc_page(gfp_t gfp, 1146 struct shmem_inode_info *info, unsigned long idx) 1147{ 1148 return alloc_page(gfp); 1149} 1150#endif 1151 1152/* 1153 * shmem_getpage - either get the page from swap or allocate a new one 1154 * 1155 * If we allocate a new one we do not mark it dirty. That's up to the 1156 * vm. If we swap it in we mark it dirty since we also free the swap 1157 * entry since a page cannot live in both the swap and page cache 1158 */ 1159static int shmem_getpage(struct inode *inode, unsigned long idx, 1160 struct page **pagep, enum sgp_type sgp, int *type) 1161{ 1162 struct address_space *mapping = inode->i_mapping; 1163 struct shmem_inode_info *info = SHMEM_I(inode); 1164 struct shmem_sb_info *sbinfo; 1165 struct page *filepage = *pagep; 1166 struct page *swappage; 1167 swp_entry_t *entry; 1168 swp_entry_t swap; 1169 gfp_t gfp; 1170 int error; 1171 1172 if (idx >= SHMEM_MAX_INDEX) 1173 return -EFBIG; 1174 1175 if (type) 1176 *type = 0; 1177 1178 /* 1179 * Normally, filepage is NULL on entry, and either found 1180 * uptodate immediately, or allocated and zeroed, or read 1181 * in under swappage, which is then assigned to filepage. 1182 * But shmem_readpage (required for splice) passes in a locked 1183 * filepage, which may be found not uptodate by other callers 1184 * too, and may need to be copied from the swappage read in. 1185 */ 1186repeat: 1187 if (!filepage) 1188 filepage = find_lock_page(mapping, idx); 1189 if (filepage && PageUptodate(filepage)) 1190 goto done; 1191 error = 0; 1192 gfp = mapping_gfp_mask(mapping); 1193 if (!filepage) { 1194 /* 1195 * Try to preload while we can wait, to not make a habit of 1196 * draining atomic reserves; but don't latch on to this cpu. 1197 */ 1198 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1199 if (error) 1200 goto failed; 1201 radix_tree_preload_end(); 1202 } 1203 1204 spin_lock(&info->lock); 1205 shmem_recalc_inode(inode); 1206 entry = shmem_swp_alloc(info, idx, sgp); 1207 if (IS_ERR(entry)) { 1208 spin_unlock(&info->lock); 1209 error = PTR_ERR(entry); 1210 goto failed; 1211 } 1212 swap = *entry; 1213 1214 if (swap.val) { 1215 /* Look it up and read it in.. */ 1216 swappage = lookup_swap_cache(swap); 1217 if (!swappage) { 1218 shmem_swp_unmap(entry); 1219 /* here we actually do the io */ 1220 if (type && !(*type & VM_FAULT_MAJOR)) { 1221 __count_vm_event(PGMAJFAULT); 1222 *type |= VM_FAULT_MAJOR; 1223 } 1224 spin_unlock(&info->lock); 1225 swappage = shmem_swapin(swap, gfp, info, idx); 1226 if (!swappage) { 1227 spin_lock(&info->lock); 1228 entry = shmem_swp_alloc(info, idx, sgp); 1229 if (IS_ERR(entry)) 1230 error = PTR_ERR(entry); 1231 else { 1232 if (entry->val == swap.val) 1233 error = -ENOMEM; 1234 shmem_swp_unmap(entry); 1235 } 1236 spin_unlock(&info->lock); 1237 if (error) 1238 goto failed; 1239 goto repeat; 1240 } 1241 wait_on_page_locked(swappage); 1242 page_cache_release(swappage); 1243 goto repeat; 1244 } 1245 1246 /* We have to do this with page locked to prevent races */ 1247 if (TestSetPageLocked(swappage)) { 1248 shmem_swp_unmap(entry); 1249 spin_unlock(&info->lock); 1250 wait_on_page_locked(swappage); 1251 page_cache_release(swappage); 1252 goto repeat; 1253 } 1254 if (PageWriteback(swappage)) { 1255 shmem_swp_unmap(entry); 1256 spin_unlock(&info->lock); 1257 wait_on_page_writeback(swappage); 1258 unlock_page(swappage); 1259 page_cache_release(swappage); 1260 goto repeat; 1261 } 1262 if (!PageUptodate(swappage)) { 1263 shmem_swp_unmap(entry); 1264 spin_unlock(&info->lock); 1265 unlock_page(swappage); 1266 page_cache_release(swappage); 1267 error = -EIO; 1268 goto failed; 1269 } 1270 1271 if (filepage) { 1272 shmem_swp_set(info, entry, 0); 1273 shmem_swp_unmap(entry); 1274 delete_from_swap_cache(swappage); 1275 spin_unlock(&info->lock); 1276 copy_highpage(filepage, swappage); 1277 unlock_page(swappage); 1278 page_cache_release(swappage); 1279 flush_dcache_page(filepage); 1280 SetPageUptodate(filepage); 1281 set_page_dirty(filepage); 1282 swap_free(swap); 1283 } else if (!(error = add_to_page_cache( 1284 swappage, mapping, idx, GFP_NOWAIT))) { 1285 info->flags |= SHMEM_PAGEIN; 1286 shmem_swp_set(info, entry, 0); 1287 shmem_swp_unmap(entry); 1288 delete_from_swap_cache(swappage); 1289 spin_unlock(&info->lock); 1290 filepage = swappage; 1291 set_page_dirty(filepage); 1292 swap_free(swap); 1293 } else { 1294 shmem_swp_unmap(entry); 1295 spin_unlock(&info->lock); 1296 unlock_page(swappage); 1297 page_cache_release(swappage); 1298 goto repeat; 1299 } 1300 } else if (sgp == SGP_READ && !filepage) { 1301 shmem_swp_unmap(entry); 1302 filepage = find_get_page(mapping, idx); 1303 if (filepage && 1304 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1305 spin_unlock(&info->lock); 1306 wait_on_page_locked(filepage); 1307 page_cache_release(filepage); 1308 filepage = NULL; 1309 goto repeat; 1310 } 1311 spin_unlock(&info->lock); 1312 } else { 1313 shmem_swp_unmap(entry); 1314 sbinfo = SHMEM_SB(inode->i_sb); 1315 if (sbinfo->max_blocks) { 1316 spin_lock(&sbinfo->stat_lock); 1317 if (sbinfo->free_blocks == 0 || 1318 shmem_acct_block(info->flags)) { 1319 spin_unlock(&sbinfo->stat_lock); 1320 spin_unlock(&info->lock); 1321 error = -ENOSPC; 1322 goto failed; 1323 } 1324 sbinfo->free_blocks--; 1325 inode->i_blocks += BLOCKS_PER_PAGE; 1326 spin_unlock(&sbinfo->stat_lock); 1327 } else if (shmem_acct_block(info->flags)) { 1328 spin_unlock(&info->lock); 1329 error = -ENOSPC; 1330 goto failed; 1331 } 1332 1333 if (!filepage) { 1334 spin_unlock(&info->lock); 1335 filepage = shmem_alloc_page(gfp, info, idx); 1336 if (!filepage) { 1337 shmem_unacct_blocks(info->flags, 1); 1338 shmem_free_blocks(inode, 1); 1339 error = -ENOMEM; 1340 goto failed; 1341 } 1342 1343 spin_lock(&info->lock); 1344 entry = shmem_swp_alloc(info, idx, sgp); 1345 if (IS_ERR(entry)) 1346 error = PTR_ERR(entry); 1347 else { 1348 swap = *entry; 1349 shmem_swp_unmap(entry); 1350 } 1351 if (error || swap.val || 0 != add_to_page_cache_lru( 1352 filepage, mapping, idx, GFP_NOWAIT)) { 1353 spin_unlock(&info->lock); 1354 page_cache_release(filepage); 1355 shmem_unacct_blocks(info->flags, 1); 1356 shmem_free_blocks(inode, 1); 1357 filepage = NULL; 1358 if (error) 1359 goto failed; 1360 goto repeat; 1361 } 1362 info->flags |= SHMEM_PAGEIN; 1363 } 1364 1365 info->alloced++; 1366 spin_unlock(&info->lock); 1367 clear_highpage(filepage); 1368 flush_dcache_page(filepage); 1369 SetPageUptodate(filepage); 1370 if (sgp == SGP_DIRTY) 1371 set_page_dirty(filepage); 1372 } 1373done: 1374 *pagep = filepage; 1375 return 0; 1376 1377failed: 1378 if (*pagep != filepage) { 1379 unlock_page(filepage); 1380 page_cache_release(filepage); 1381 } 1382 return error; 1383} 1384 1385static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1386{ 1387 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1388 int error; 1389 int ret; 1390 1391 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1392 return VM_FAULT_SIGBUS; 1393 1394 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1395 if (error) 1396 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1397 1398 mark_page_accessed(vmf->page); 1399 return ret | VM_FAULT_LOCKED; 1400} 1401 1402#ifdef CONFIG_NUMA 1403static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1404{ 1405 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1406 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1407} 1408 1409static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1410 unsigned long addr) 1411{ 1412 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1413 unsigned long idx; 1414 1415 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1416 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1417} 1418#endif 1419 1420int shmem_lock(struct file *file, int lock, struct user_struct *user) 1421{ 1422 struct inode *inode = file->f_path.dentry->d_inode; 1423 struct shmem_inode_info *info = SHMEM_I(inode); 1424 int retval = -ENOMEM; 1425 1426 spin_lock(&info->lock); 1427 if (lock && !(info->flags & VM_LOCKED)) { 1428 if (!user_shm_lock(inode->i_size, user)) 1429 goto out_nomem; 1430 info->flags |= VM_LOCKED; 1431 } 1432 if (!lock && (info->flags & VM_LOCKED) && user) { 1433 user_shm_unlock(inode->i_size, user); 1434 info->flags &= ~VM_LOCKED; 1435 } 1436 retval = 0; 1437out_nomem: 1438 spin_unlock(&info->lock); 1439 return retval; 1440} 1441 1442static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1443{ 1444 file_accessed(file); 1445 vma->vm_ops = &shmem_vm_ops; 1446 vma->vm_flags |= VM_CAN_NONLINEAR; 1447 return 0; 1448} 1449 1450static struct inode * 1451shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1452{ 1453 struct inode *inode; 1454 struct shmem_inode_info *info; 1455 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1456 1457 if (shmem_reserve_inode(sb)) 1458 return NULL; 1459 1460 inode = new_inode(sb); 1461 if (inode) { 1462 inode->i_mode = mode; 1463 inode->i_uid = current->fsuid; 1464 inode->i_gid = current->fsgid; 1465 inode->i_blocks = 0; 1466 inode->i_mapping->a_ops = &shmem_aops; 1467 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1468 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1469 inode->i_generation = get_seconds(); 1470 info = SHMEM_I(inode); 1471 memset(info, 0, (char *)inode - (char *)info); 1472 spin_lock_init(&info->lock); 1473 INIT_LIST_HEAD(&info->swaplist); 1474 1475 switch (mode & S_IFMT) { 1476 default: 1477 inode->i_op = &shmem_special_inode_operations; 1478 init_special_inode(inode, mode, dev); 1479 break; 1480 case S_IFREG: 1481 inode->i_op = &shmem_inode_operations; 1482 inode->i_fop = &shmem_file_operations; 1483 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1484 &sbinfo->policy_nodes); 1485 break; 1486 case S_IFDIR: 1487 inc_nlink(inode); 1488 /* Some things misbehave if size == 0 on a directory */ 1489 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1490 inode->i_op = &shmem_dir_inode_operations; 1491 inode->i_fop = &simple_dir_operations; 1492 break; 1493 case S_IFLNK: 1494 /* 1495 * Must not load anything in the rbtree, 1496 * mpol_free_shared_policy will not be called. 1497 */ 1498 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1499 NULL); 1500 break; 1501 } 1502 } else 1503 shmem_free_inode(sb); 1504 return inode; 1505} 1506 1507#ifdef CONFIG_TMPFS 1508static const struct inode_operations shmem_symlink_inode_operations; 1509static const struct inode_operations shmem_symlink_inline_operations; 1510 1511/* 1512 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1513 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1514 * below the loop driver, in the generic fashion that many filesystems support. 1515 */ 1516static int shmem_readpage(struct file *file, struct page *page) 1517{ 1518 struct inode *inode = page->mapping->host; 1519 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1520 unlock_page(page); 1521 return error; 1522} 1523 1524static int 1525shmem_write_begin(struct file *file, struct address_space *mapping, 1526 loff_t pos, unsigned len, unsigned flags, 1527 struct page **pagep, void **fsdata) 1528{ 1529 struct inode *inode = mapping->host; 1530 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1531 *pagep = NULL; 1532 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1533} 1534 1535static int 1536shmem_write_end(struct file *file, struct address_space *mapping, 1537 loff_t pos, unsigned len, unsigned copied, 1538 struct page *page, void *fsdata) 1539{ 1540 struct inode *inode = mapping->host; 1541 1542 if (pos + copied > inode->i_size) 1543 i_size_write(inode, pos + copied); 1544 1545 unlock_page(page); 1546 set_page_dirty(page); 1547 page_cache_release(page); 1548 1549 return copied; 1550} 1551 1552static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1553{ 1554 struct inode *inode = filp->f_path.dentry->d_inode; 1555 struct address_space *mapping = inode->i_mapping; 1556 unsigned long index, offset; 1557 enum sgp_type sgp = SGP_READ; 1558 1559 /* 1560 * Might this read be for a stacking filesystem? Then when reading 1561 * holes of a sparse file, we actually need to allocate those pages, 1562 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1563 */ 1564 if (segment_eq(get_fs(), KERNEL_DS)) 1565 sgp = SGP_DIRTY; 1566 1567 index = *ppos >> PAGE_CACHE_SHIFT; 1568 offset = *ppos & ~PAGE_CACHE_MASK; 1569 1570 for (;;) { 1571 struct page *page = NULL; 1572 unsigned long end_index, nr, ret; 1573 loff_t i_size = i_size_read(inode); 1574 1575 end_index = i_size >> PAGE_CACHE_SHIFT; 1576 if (index > end_index) 1577 break; 1578 if (index == end_index) { 1579 nr = i_size & ~PAGE_CACHE_MASK; 1580 if (nr <= offset) 1581 break; 1582 } 1583 1584 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1585 if (desc->error) { 1586 if (desc->error == -EINVAL) 1587 desc->error = 0; 1588 break; 1589 } 1590 if (page) 1591 unlock_page(page); 1592 1593 /* 1594 * We must evaluate after, since reads (unlike writes) 1595 * are called without i_mutex protection against truncate 1596 */ 1597 nr = PAGE_CACHE_SIZE; 1598 i_size = i_size_read(inode); 1599 end_index = i_size >> PAGE_CACHE_SHIFT; 1600 if (index == end_index) { 1601 nr = i_size & ~PAGE_CACHE_MASK; 1602 if (nr <= offset) { 1603 if (page) 1604 page_cache_release(page); 1605 break; 1606 } 1607 } 1608 nr -= offset; 1609 1610 if (page) { 1611 /* 1612 * If users can be writing to this page using arbitrary 1613 * virtual addresses, take care about potential aliasing 1614 * before reading the page on the kernel side. 1615 */ 1616 if (mapping_writably_mapped(mapping)) 1617 flush_dcache_page(page); 1618 /* 1619 * Mark the page accessed if we read the beginning. 1620 */ 1621 if (!offset) 1622 mark_page_accessed(page); 1623 } else { 1624 page = ZERO_PAGE(0); 1625 page_cache_get(page); 1626 } 1627 1628 /* 1629 * Ok, we have the page, and it's up-to-date, so 1630 * now we can copy it to user space... 1631 * 1632 * The actor routine returns how many bytes were actually used.. 1633 * NOTE! This may not be the same as how much of a user buffer 1634 * we filled up (we may be padding etc), so we can only update 1635 * "pos" here (the actor routine has to update the user buffer 1636 * pointers and the remaining count). 1637 */ 1638 ret = actor(desc, page, offset, nr); 1639 offset += ret; 1640 index += offset >> PAGE_CACHE_SHIFT; 1641 offset &= ~PAGE_CACHE_MASK; 1642 1643 page_cache_release(page); 1644 if (ret != nr || !desc->count) 1645 break; 1646 1647 cond_resched(); 1648 } 1649 1650 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1651 file_accessed(filp); 1652} 1653 1654static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1655{ 1656 read_descriptor_t desc; 1657 1658 if ((ssize_t) count < 0) 1659 return -EINVAL; 1660 if (!access_ok(VERIFY_WRITE, buf, count)) 1661 return -EFAULT; 1662 if (!count) 1663 return 0; 1664 1665 desc.written = 0; 1666 desc.count = count; 1667 desc.arg.buf = buf; 1668 desc.error = 0; 1669 1670 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1671 if (desc.written) 1672 return desc.written; 1673 return desc.error; 1674} 1675 1676static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1677{ 1678 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1679 1680 buf->f_type = TMPFS_MAGIC; 1681 buf->f_bsize = PAGE_CACHE_SIZE; 1682 buf->f_namelen = NAME_MAX; 1683 spin_lock(&sbinfo->stat_lock); 1684 if (sbinfo->max_blocks) { 1685 buf->f_blocks = sbinfo->max_blocks; 1686 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1687 } 1688 if (sbinfo->max_inodes) { 1689 buf->f_files = sbinfo->max_inodes; 1690 buf->f_ffree = sbinfo->free_inodes; 1691 } 1692 /* else leave those fields 0 like simple_statfs */ 1693 spin_unlock(&sbinfo->stat_lock); 1694 return 0; 1695} 1696 1697/* 1698 * File creation. Allocate an inode, and we're done.. 1699 */ 1700static int 1701shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1702{ 1703 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1704 int error = -ENOSPC; 1705 1706 if (inode) { 1707 error = security_inode_init_security(inode, dir, NULL, NULL, 1708 NULL); 1709 if (error) { 1710 if (error != -EOPNOTSUPP) { 1711 iput(inode); 1712 return error; 1713 } 1714 } 1715 error = shmem_acl_init(inode, dir); 1716 if (error) { 1717 iput(inode); 1718 return error; 1719 } 1720 if (dir->i_mode & S_ISGID) { 1721 inode->i_gid = dir->i_gid; 1722 if (S_ISDIR(mode)) 1723 inode->i_mode |= S_ISGID; 1724 } 1725 dir->i_size += BOGO_DIRENT_SIZE; 1726 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1727 d_instantiate(dentry, inode); 1728 dget(dentry); /* Extra count - pin the dentry in core */ 1729 } 1730 return error; 1731} 1732 1733static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1734{ 1735 int error; 1736 1737 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1738 return error; 1739 inc_nlink(dir); 1740 return 0; 1741} 1742 1743static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1744 struct nameidata *nd) 1745{ 1746 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1747} 1748 1749/* 1750 * Link a file.. 1751 */ 1752static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1753{ 1754 struct inode *inode = old_dentry->d_inode; 1755 int ret; 1756 1757 /* 1758 * No ordinary (disk based) filesystem counts links as inodes; 1759 * but each new link needs a new dentry, pinning lowmem, and 1760 * tmpfs dentries cannot be pruned until they are unlinked. 1761 */ 1762 ret = shmem_reserve_inode(inode->i_sb); 1763 if (ret) 1764 goto out; 1765 1766 dir->i_size += BOGO_DIRENT_SIZE; 1767 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1768 inc_nlink(inode); 1769 atomic_inc(&inode->i_count); /* New dentry reference */ 1770 dget(dentry); /* Extra pinning count for the created dentry */ 1771 d_instantiate(dentry, inode); 1772out: 1773 return ret; 1774} 1775 1776static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1777{ 1778 struct inode *inode = dentry->d_inode; 1779 1780 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1781 shmem_free_inode(inode->i_sb); 1782 1783 dir->i_size -= BOGO_DIRENT_SIZE; 1784 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1785 drop_nlink(inode); 1786 dput(dentry); /* Undo the count from "create" - this does all the work */ 1787 return 0; 1788} 1789 1790static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1791{ 1792 if (!simple_empty(dentry)) 1793 return -ENOTEMPTY; 1794 1795 drop_nlink(dentry->d_inode); 1796 drop_nlink(dir); 1797 return shmem_unlink(dir, dentry); 1798} 1799 1800/* 1801 * The VFS layer already does all the dentry stuff for rename, 1802 * we just have to decrement the usage count for the target if 1803 * it exists so that the VFS layer correctly free's it when it 1804 * gets overwritten. 1805 */ 1806static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1807{ 1808 struct inode *inode = old_dentry->d_inode; 1809 int they_are_dirs = S_ISDIR(inode->i_mode); 1810 1811 if (!simple_empty(new_dentry)) 1812 return -ENOTEMPTY; 1813 1814 if (new_dentry->d_inode) { 1815 (void) shmem_unlink(new_dir, new_dentry); 1816 if (they_are_dirs) 1817 drop_nlink(old_dir); 1818 } else if (they_are_dirs) { 1819 drop_nlink(old_dir); 1820 inc_nlink(new_dir); 1821 } 1822 1823 old_dir->i_size -= BOGO_DIRENT_SIZE; 1824 new_dir->i_size += BOGO_DIRENT_SIZE; 1825 old_dir->i_ctime = old_dir->i_mtime = 1826 new_dir->i_ctime = new_dir->i_mtime = 1827 inode->i_ctime = CURRENT_TIME; 1828 return 0; 1829} 1830 1831static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1832{ 1833 int error; 1834 int len; 1835 struct inode *inode; 1836 struct page *page = NULL; 1837 char *kaddr; 1838 struct shmem_inode_info *info; 1839 1840 len = strlen(symname) + 1; 1841 if (len > PAGE_CACHE_SIZE) 1842 return -ENAMETOOLONG; 1843 1844 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1845 if (!inode) 1846 return -ENOSPC; 1847 1848 error = security_inode_init_security(inode, dir, NULL, NULL, 1849 NULL); 1850 if (error) { 1851 if (error != -EOPNOTSUPP) { 1852 iput(inode); 1853 return error; 1854 } 1855 error = 0; 1856 } 1857 1858 info = SHMEM_I(inode); 1859 inode->i_size = len-1; 1860 if (len <= (char *)inode - (char *)info) { 1861 /* do it inline */ 1862 memcpy(info, symname, len); 1863 inode->i_op = &shmem_symlink_inline_operations; 1864 } else { 1865 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1866 if (error) { 1867 iput(inode); 1868 return error; 1869 } 1870 unlock_page(page); 1871 inode->i_op = &shmem_symlink_inode_operations; 1872 kaddr = kmap_atomic(page, KM_USER0); 1873 memcpy(kaddr, symname, len); 1874 kunmap_atomic(kaddr, KM_USER0); 1875 set_page_dirty(page); 1876 page_cache_release(page); 1877 } 1878 if (dir->i_mode & S_ISGID) 1879 inode->i_gid = dir->i_gid; 1880 dir->i_size += BOGO_DIRENT_SIZE; 1881 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1882 d_instantiate(dentry, inode); 1883 dget(dentry); 1884 return 0; 1885} 1886 1887static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1888{ 1889 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1890 return NULL; 1891} 1892 1893static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1894{ 1895 struct page *page = NULL; 1896 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1897 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1898 if (page) 1899 unlock_page(page); 1900 return page; 1901} 1902 1903static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1904{ 1905 if (!IS_ERR(nd_get_link(nd))) { 1906 struct page *page = cookie; 1907 kunmap(page); 1908 mark_page_accessed(page); 1909 page_cache_release(page); 1910 } 1911} 1912 1913static const struct inode_operations shmem_symlink_inline_operations = { 1914 .readlink = generic_readlink, 1915 .follow_link = shmem_follow_link_inline, 1916}; 1917 1918static const struct inode_operations shmem_symlink_inode_operations = { 1919 .truncate = shmem_truncate, 1920 .readlink = generic_readlink, 1921 .follow_link = shmem_follow_link, 1922 .put_link = shmem_put_link, 1923}; 1924 1925#ifdef CONFIG_TMPFS_POSIX_ACL 1926/** 1927 * Superblocks without xattr inode operations will get security.* xattr 1928 * support from the VFS "for free". As soon as we have any other xattrs 1929 * like ACLs, we also need to implement the security.* handlers at 1930 * filesystem level, though. 1931 */ 1932 1933static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1934 size_t list_len, const char *name, 1935 size_t name_len) 1936{ 1937 return security_inode_listsecurity(inode, list, list_len); 1938} 1939 1940static int shmem_xattr_security_get(struct inode *inode, const char *name, 1941 void *buffer, size_t size) 1942{ 1943 if (strcmp(name, "") == 0) 1944 return -EINVAL; 1945 return security_inode_getsecurity(inode, name, buffer, size, 1946 -EOPNOTSUPP); 1947} 1948 1949static int shmem_xattr_security_set(struct inode *inode, const char *name, 1950 const void *value, size_t size, int flags) 1951{ 1952 if (strcmp(name, "") == 0) 1953 return -EINVAL; 1954 return security_inode_setsecurity(inode, name, value, size, flags); 1955} 1956 1957static struct xattr_handler shmem_xattr_security_handler = { 1958 .prefix = XATTR_SECURITY_PREFIX, 1959 .list = shmem_xattr_security_list, 1960 .get = shmem_xattr_security_get, 1961 .set = shmem_xattr_security_set, 1962}; 1963 1964static struct xattr_handler *shmem_xattr_handlers[] = { 1965 &shmem_xattr_acl_access_handler, 1966 &shmem_xattr_acl_default_handler, 1967 &shmem_xattr_security_handler, 1968 NULL 1969}; 1970#endif 1971 1972static struct dentry *shmem_get_parent(struct dentry *child) 1973{ 1974 return ERR_PTR(-ESTALE); 1975} 1976 1977static int shmem_match(struct inode *ino, void *vfh) 1978{ 1979 __u32 *fh = vfh; 1980 __u64 inum = fh[2]; 1981 inum = (inum << 32) | fh[1]; 1982 return ino->i_ino == inum && fh[0] == ino->i_generation; 1983} 1984 1985static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 1986 struct fid *fid, int fh_len, int fh_type) 1987{ 1988 struct inode *inode; 1989 struct dentry *dentry = NULL; 1990 u64 inum = fid->raw[2]; 1991 inum = (inum << 32) | fid->raw[1]; 1992 1993 if (fh_len < 3) 1994 return NULL; 1995 1996 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 1997 shmem_match, fid->raw); 1998 if (inode) { 1999 dentry = d_find_alias(inode); 2000 iput(inode); 2001 } 2002 2003 return dentry; 2004} 2005 2006static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2007 int connectable) 2008{ 2009 struct inode *inode = dentry->d_inode; 2010 2011 if (*len < 3) 2012 return 255; 2013 2014 if (hlist_unhashed(&inode->i_hash)) { 2015 /* Unfortunately insert_inode_hash is not idempotent, 2016 * so as we hash inodes here rather than at creation 2017 * time, we need a lock to ensure we only try 2018 * to do it once 2019 */ 2020 static DEFINE_SPINLOCK(lock); 2021 spin_lock(&lock); 2022 if (hlist_unhashed(&inode->i_hash)) 2023 __insert_inode_hash(inode, 2024 inode->i_ino + inode->i_generation); 2025 spin_unlock(&lock); 2026 } 2027 2028 fh[0] = inode->i_generation; 2029 fh[1] = inode->i_ino; 2030 fh[2] = ((__u64)inode->i_ino) >> 32; 2031 2032 *len = 3; 2033 return 1; 2034} 2035 2036static const struct export_operations shmem_export_ops = { 2037 .get_parent = shmem_get_parent, 2038 .encode_fh = shmem_encode_fh, 2039 .fh_to_dentry = shmem_fh_to_dentry, 2040}; 2041 2042static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2043 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2044 int *policy, nodemask_t *policy_nodes) 2045{ 2046 char *this_char, *value, *rest; 2047 2048 while (options != NULL) { 2049 this_char = options; 2050 for (;;) { 2051 /* 2052 * NUL-terminate this option: unfortunately, 2053 * mount options form a comma-separated list, 2054 * but mpol's nodelist may also contain commas. 2055 */ 2056 options = strchr(options, ','); 2057 if (options == NULL) 2058 break; 2059 options++; 2060 if (!isdigit(*options)) { 2061 options[-1] = '\0'; 2062 break; 2063 } 2064 } 2065 if (!*this_char) 2066 continue; 2067 if ((value = strchr(this_char,'=')) != NULL) { 2068 *value++ = 0; 2069 } else { 2070 printk(KERN_ERR 2071 "tmpfs: No value for mount option '%s'\n", 2072 this_char); 2073 return 1; 2074 } 2075 2076 if (!strcmp(this_char,"size")) { 2077 unsigned long long size; 2078 size = memparse(value,&rest); 2079 if (*rest == '%') { 2080 size <<= PAGE_SHIFT; 2081 size *= totalram_pages; 2082 do_div(size, 100); 2083 rest++; 2084 } 2085 if (*rest) 2086 goto bad_val; 2087 *blocks = DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2088 } else if (!strcmp(this_char,"nr_blocks")) { 2089 *blocks = memparse(value,&rest); 2090 if (*rest) 2091 goto bad_val; 2092 } else if (!strcmp(this_char,"nr_inodes")) { 2093 *inodes = memparse(value,&rest); 2094 if (*rest) 2095 goto bad_val; 2096 } else if (!strcmp(this_char,"mode")) { 2097 if (!mode) 2098 continue; 2099 *mode = simple_strtoul(value,&rest,8); 2100 if (*rest) 2101 goto bad_val; 2102 } else if (!strcmp(this_char,"uid")) { 2103 if (!uid) 2104 continue; 2105 *uid = simple_strtoul(value,&rest,0); 2106 if (*rest) 2107 goto bad_val; 2108 } else if (!strcmp(this_char,"gid")) { 2109 if (!gid) 2110 continue; 2111 *gid = simple_strtoul(value,&rest,0); 2112 if (*rest) 2113 goto bad_val; 2114 } else if (!strcmp(this_char,"mpol")) { 2115 if (shmem_parse_mpol(value,policy,policy_nodes)) 2116 goto bad_val; 2117 } else { 2118 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2119 this_char); 2120 return 1; 2121 } 2122 } 2123 return 0; 2124 2125bad_val: 2126 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2127 value, this_char); 2128 return 1; 2129 2130} 2131 2132static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2133{ 2134 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2135 unsigned long max_blocks = sbinfo->max_blocks; 2136 unsigned long max_inodes = sbinfo->max_inodes; 2137 int policy = sbinfo->policy; 2138 nodemask_t policy_nodes = sbinfo->policy_nodes; 2139 unsigned long blocks; 2140 unsigned long inodes; 2141 int error = -EINVAL; 2142 2143 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2144 &max_inodes, &policy, &policy_nodes)) 2145 return error; 2146 2147 spin_lock(&sbinfo->stat_lock); 2148 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2149 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2150 if (max_blocks < blocks) 2151 goto out; 2152 if (max_inodes < inodes) 2153 goto out; 2154 /* 2155 * Those tests also disallow limited->unlimited while any are in 2156 * use, so i_blocks will always be zero when max_blocks is zero; 2157 * but we must separately disallow unlimited->limited, because 2158 * in that case we have no record of how much is already in use. 2159 */ 2160 if (max_blocks && !sbinfo->max_blocks) 2161 goto out; 2162 if (max_inodes && !sbinfo->max_inodes) 2163 goto out; 2164 2165 error = 0; 2166 sbinfo->max_blocks = max_blocks; 2167 sbinfo->free_blocks = max_blocks - blocks; 2168 sbinfo->max_inodes = max_inodes; 2169 sbinfo->free_inodes = max_inodes - inodes; 2170 sbinfo->policy = policy; 2171 sbinfo->policy_nodes = policy_nodes; 2172out: 2173 spin_unlock(&sbinfo->stat_lock); 2174 return error; 2175} 2176#endif 2177 2178static void shmem_put_super(struct super_block *sb) 2179{ 2180 kfree(sb->s_fs_info); 2181 sb->s_fs_info = NULL; 2182} 2183 2184static int shmem_fill_super(struct super_block *sb, 2185 void *data, int silent) 2186{ 2187 struct inode *inode; 2188 struct dentry *root; 2189 int mode = S_IRWXUGO | S_ISVTX; 2190 uid_t uid = current->fsuid; 2191 gid_t gid = current->fsgid; 2192 int err = -ENOMEM; 2193 struct shmem_sb_info *sbinfo; 2194 unsigned long blocks = 0; 2195 unsigned long inodes = 0; 2196 int policy = MPOL_DEFAULT; 2197 nodemask_t policy_nodes = node_states[N_HIGH_MEMORY]; 2198 2199#ifdef CONFIG_TMPFS 2200 /* 2201 * Per default we only allow half of the physical ram per 2202 * tmpfs instance, limiting inodes to one per page of lowmem; 2203 * but the internal instance is left unlimited. 2204 */ 2205 if (!(sb->s_flags & MS_NOUSER)) { 2206 blocks = totalram_pages / 2; 2207 inodes = totalram_pages - totalhigh_pages; 2208 if (inodes > blocks) 2209 inodes = blocks; 2210 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2211 &inodes, &policy, &policy_nodes)) 2212 return -EINVAL; 2213 } 2214 sb->s_export_op = &shmem_export_ops; 2215#else 2216 sb->s_flags |= MS_NOUSER; 2217#endif 2218 2219 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2220 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2221 L1_CACHE_BYTES), GFP_KERNEL); 2222 if (!sbinfo) 2223 return -ENOMEM; 2224 2225 spin_lock_init(&sbinfo->stat_lock); 2226 sbinfo->max_blocks = blocks; 2227 sbinfo->free_blocks = blocks; 2228 sbinfo->max_inodes = inodes; 2229 sbinfo->free_inodes = inodes; 2230 sbinfo->policy = policy; 2231 sbinfo->policy_nodes = policy_nodes; 2232 2233 sb->s_fs_info = sbinfo; 2234 sb->s_maxbytes = SHMEM_MAX_BYTES; 2235 sb->s_blocksize = PAGE_CACHE_SIZE; 2236 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2237 sb->s_magic = TMPFS_MAGIC; 2238 sb->s_op = &shmem_ops; 2239 sb->s_time_gran = 1; 2240#ifdef CONFIG_TMPFS_POSIX_ACL 2241 sb->s_xattr = shmem_xattr_handlers; 2242 sb->s_flags |= MS_POSIXACL; 2243#endif 2244 2245 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2246 if (!inode) 2247 goto failed; 2248 inode->i_uid = uid; 2249 inode->i_gid = gid; 2250 root = d_alloc_root(inode); 2251 if (!root) 2252 goto failed_iput; 2253 sb->s_root = root; 2254 return 0; 2255 2256failed_iput: 2257 iput(inode); 2258failed: 2259 shmem_put_super(sb); 2260 return err; 2261} 2262 2263static struct kmem_cache *shmem_inode_cachep; 2264 2265static struct inode *shmem_alloc_inode(struct super_block *sb) 2266{ 2267 struct shmem_inode_info *p; 2268 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2269 if (!p) 2270 return NULL; 2271 return &p->vfs_inode; 2272} 2273 2274static void shmem_destroy_inode(struct inode *inode) 2275{ 2276 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2277 /* only struct inode is valid if it's an inline symlink */ 2278 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2279 } 2280 shmem_acl_destroy_inode(inode); 2281 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2282} 2283 2284static void init_once(struct kmem_cache *cachep, void *foo) 2285{ 2286 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2287 2288 inode_init_once(&p->vfs_inode); 2289#ifdef CONFIG_TMPFS_POSIX_ACL 2290 p->i_acl = NULL; 2291 p->i_default_acl = NULL; 2292#endif 2293} 2294 2295static int init_inodecache(void) 2296{ 2297 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2298 sizeof(struct shmem_inode_info), 2299 0, SLAB_PANIC, init_once); 2300 return 0; 2301} 2302 2303static void destroy_inodecache(void) 2304{ 2305 kmem_cache_destroy(shmem_inode_cachep); 2306} 2307 2308static const struct address_space_operations shmem_aops = { 2309 .writepage = shmem_writepage, 2310 .set_page_dirty = __set_page_dirty_no_writeback, 2311#ifdef CONFIG_TMPFS 2312 .readpage = shmem_readpage, 2313 .write_begin = shmem_write_begin, 2314 .write_end = shmem_write_end, 2315#endif 2316 .migratepage = migrate_page, 2317}; 2318 2319static const struct file_operations shmem_file_operations = { 2320 .mmap = shmem_mmap, 2321#ifdef CONFIG_TMPFS 2322 .llseek = generic_file_llseek, 2323 .read = shmem_file_read, 2324 .write = do_sync_write, 2325 .aio_write = generic_file_aio_write, 2326 .fsync = simple_sync_file, 2327 .splice_read = generic_file_splice_read, 2328 .splice_write = generic_file_splice_write, 2329#endif 2330}; 2331 2332static const struct inode_operations shmem_inode_operations = { 2333 .truncate = shmem_truncate, 2334 .setattr = shmem_notify_change, 2335 .truncate_range = shmem_truncate_range, 2336#ifdef CONFIG_TMPFS_POSIX_ACL 2337 .setxattr = generic_setxattr, 2338 .getxattr = generic_getxattr, 2339 .listxattr = generic_listxattr, 2340 .removexattr = generic_removexattr, 2341 .permission = shmem_permission, 2342#endif 2343 2344}; 2345 2346static const struct inode_operations shmem_dir_inode_operations = { 2347#ifdef CONFIG_TMPFS 2348 .create = shmem_create, 2349 .lookup = simple_lookup, 2350 .link = shmem_link, 2351 .unlink = shmem_unlink, 2352 .symlink = shmem_symlink, 2353 .mkdir = shmem_mkdir, 2354 .rmdir = shmem_rmdir, 2355 .mknod = shmem_mknod, 2356 .rename = shmem_rename, 2357#endif 2358#ifdef CONFIG_TMPFS_POSIX_ACL 2359 .setattr = shmem_notify_change, 2360 .setxattr = generic_setxattr, 2361 .getxattr = generic_getxattr, 2362 .listxattr = generic_listxattr, 2363 .removexattr = generic_removexattr, 2364 .permission = shmem_permission, 2365#endif 2366}; 2367 2368static const struct inode_operations shmem_special_inode_operations = { 2369#ifdef CONFIG_TMPFS_POSIX_ACL 2370 .setattr = shmem_notify_change, 2371 .setxattr = generic_setxattr, 2372 .getxattr = generic_getxattr, 2373 .listxattr = generic_listxattr, 2374 .removexattr = generic_removexattr, 2375 .permission = shmem_permission, 2376#endif 2377}; 2378 2379static const struct super_operations shmem_ops = { 2380 .alloc_inode = shmem_alloc_inode, 2381 .destroy_inode = shmem_destroy_inode, 2382#ifdef CONFIG_TMPFS 2383 .statfs = shmem_statfs, 2384 .remount_fs = shmem_remount_fs, 2385#endif 2386 .delete_inode = shmem_delete_inode, 2387 .drop_inode = generic_delete_inode, 2388 .put_super = shmem_put_super, 2389}; 2390 2391static struct vm_operations_struct shmem_vm_ops = { 2392 .fault = shmem_fault, 2393#ifdef CONFIG_NUMA 2394 .set_policy = shmem_set_policy, 2395 .get_policy = shmem_get_policy, 2396#endif 2397}; 2398 2399 2400static int shmem_get_sb(struct file_system_type *fs_type, 2401 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2402{ 2403 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2404} 2405 2406static struct file_system_type tmpfs_fs_type = { 2407 .owner = THIS_MODULE, 2408 .name = "tmpfs", 2409 .get_sb = shmem_get_sb, 2410 .kill_sb = kill_litter_super, 2411}; 2412static struct vfsmount *shm_mnt; 2413 2414static int __init init_tmpfs(void) 2415{ 2416 int error; 2417 2418 error = bdi_init(&shmem_backing_dev_info); 2419 if (error) 2420 goto out4; 2421 2422 error = init_inodecache(); 2423 if (error) 2424 goto out3; 2425 2426 error = register_filesystem(&tmpfs_fs_type); 2427 if (error) { 2428 printk(KERN_ERR "Could not register tmpfs\n"); 2429 goto out2; 2430 } 2431 2432 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2433 tmpfs_fs_type.name, NULL); 2434 if (IS_ERR(shm_mnt)) { 2435 error = PTR_ERR(shm_mnt); 2436 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2437 goto out1; 2438 } 2439 return 0; 2440 2441out1: 2442 unregister_filesystem(&tmpfs_fs_type); 2443out2: 2444 destroy_inodecache(); 2445out3: 2446 bdi_destroy(&shmem_backing_dev_info); 2447out4: 2448 shm_mnt = ERR_PTR(error); 2449 return error; 2450} 2451module_init(init_tmpfs) 2452 2453/* 2454 * shmem_file_setup - get an unlinked file living in tmpfs 2455 * 2456 * @name: name for dentry (to be seen in /proc/<pid>/maps 2457 * @size: size to be set for the file 2458 * 2459 */ 2460struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2461{ 2462 int error; 2463 struct file *file; 2464 struct inode *inode; 2465 struct dentry *dentry, *root; 2466 struct qstr this; 2467 2468 if (IS_ERR(shm_mnt)) 2469 return (void *)shm_mnt; 2470 2471 if (size < 0 || size > SHMEM_MAX_BYTES) 2472 return ERR_PTR(-EINVAL); 2473 2474 if (shmem_acct_size(flags, size)) 2475 return ERR_PTR(-ENOMEM); 2476 2477 error = -ENOMEM; 2478 this.name = name; 2479 this.len = strlen(name); 2480 this.hash = 0; /* will go */ 2481 root = shm_mnt->mnt_root; 2482 dentry = d_alloc(root, &this); 2483 if (!dentry) 2484 goto put_memory; 2485 2486 error = -ENFILE; 2487 file = get_empty_filp(); 2488 if (!file) 2489 goto put_dentry; 2490 2491 error = -ENOSPC; 2492 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2493 if (!inode) 2494 goto close_file; 2495 2496 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2497 d_instantiate(dentry, inode); 2498 inode->i_size = size; 2499 inode->i_nlink = 0; /* It is unlinked */ 2500 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ, 2501 &shmem_file_operations); 2502 return file; 2503 2504close_file: 2505 put_filp(file); 2506put_dentry: 2507 dput(dentry); 2508put_memory: 2509 shmem_unacct_size(flags, size); 2510 return ERR_PTR(error); 2511} 2512 2513/* 2514 * shmem_zero_setup - setup a shared anonymous mapping 2515 * 2516 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2517 */ 2518int shmem_zero_setup(struct vm_area_struct *vma) 2519{ 2520 struct file *file; 2521 loff_t size = vma->vm_end - vma->vm_start; 2522 2523 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2524 if (IS_ERR(file)) 2525 return PTR_ERR(file); 2526 2527 if (vma->vm_file) 2528 fput(vma->vm_file); 2529 vma->vm_file = file; 2530 vma->vm_ops = &shmem_vm_ops; 2531 return 0; 2532} 2533