shmem.c revision 1df9f0a73178718969ae47d813b8e7aab2cf073c
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#include <linux/seq_file.h> 53#include <linux/magic.h> 54#include <linux/ima.h> 55 56#include <asm/uaccess.h> 57#include <asm/div64.h> 58#include <asm/pgtable.h> 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 87#ifdef CONFIG_TMPFS 88static unsigned long shmem_default_max_blocks(void) 89{ 90 return totalram_pages / 2; 91} 92 93static unsigned long shmem_default_max_inodes(void) 94{ 95 return min(totalram_pages - totalhigh_pages, totalram_pages / 2); 96} 97#endif 98 99static int shmem_getpage(struct inode *inode, unsigned long idx, 100 struct page **pagep, enum sgp_type sgp, int *type); 101 102static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 103{ 104 /* 105 * The above definition of ENTRIES_PER_PAGE, and the use of 106 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 107 * might be reconsidered if it ever diverges from PAGE_SIZE. 108 * 109 * Mobility flags are masked out as swap vectors cannot move 110 */ 111 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, 112 PAGE_CACHE_SHIFT-PAGE_SHIFT); 113} 114 115static inline void shmem_dir_free(struct page *page) 116{ 117 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 118} 119 120static struct page **shmem_dir_map(struct page *page) 121{ 122 return (struct page **)kmap_atomic(page, KM_USER0); 123} 124 125static inline void shmem_dir_unmap(struct page **dir) 126{ 127 kunmap_atomic(dir, KM_USER0); 128} 129 130static swp_entry_t *shmem_swp_map(struct page *page) 131{ 132 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 133} 134 135static inline void shmem_swp_balance_unmap(void) 136{ 137 /* 138 * When passing a pointer to an i_direct entry, to code which 139 * also handles indirect entries and so will shmem_swp_unmap, 140 * we must arrange for the preempt count to remain in balance. 141 * What kmap_atomic of a lowmem page does depends on config 142 * and architecture, so pretend to kmap_atomic some lowmem page. 143 */ 144 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 145} 146 147static inline void shmem_swp_unmap(swp_entry_t *entry) 148{ 149 kunmap_atomic(entry, KM_USER1); 150} 151 152static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 153{ 154 return sb->s_fs_info; 155} 156 157/* 158 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 159 * for shared memory and for shared anonymous (/dev/zero) mappings 160 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 161 * consistent with the pre-accounting of private mappings ... 162 */ 163static inline int shmem_acct_size(unsigned long flags, loff_t size) 164{ 165 return (flags & VM_ACCOUNT) ? 166 security_vm_enough_memory_kern(VM_ACCT(size)) : 0; 167} 168 169static inline void shmem_unacct_size(unsigned long flags, loff_t size) 170{ 171 if (flags & VM_ACCOUNT) 172 vm_unacct_memory(VM_ACCT(size)); 173} 174 175/* 176 * ... whereas tmpfs objects are accounted incrementally as 177 * pages are allocated, in order to allow huge sparse files. 178 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 179 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 180 */ 181static inline int shmem_acct_block(unsigned long flags) 182{ 183 return (flags & VM_ACCOUNT) ? 184 0 : security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)); 185} 186 187static inline void shmem_unacct_blocks(unsigned long flags, long pages) 188{ 189 if (!(flags & VM_ACCOUNT)) 190 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 191} 192 193static const struct super_operations shmem_ops; 194static const struct address_space_operations shmem_aops; 195static const struct file_operations shmem_file_operations; 196static const struct inode_operations shmem_inode_operations; 197static const struct inode_operations shmem_dir_inode_operations; 198static const struct inode_operations shmem_special_inode_operations; 199static struct vm_operations_struct shmem_vm_ops; 200 201static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 202 .ra_pages = 0, /* No readahead */ 203 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, 204 .unplug_io_fn = default_unplug_io_fn, 205}; 206 207static LIST_HEAD(shmem_swaplist); 208static DEFINE_MUTEX(shmem_swaplist_mutex); 209 210static void shmem_free_blocks(struct inode *inode, long pages) 211{ 212 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 213 if (sbinfo->max_blocks) { 214 spin_lock(&sbinfo->stat_lock); 215 sbinfo->free_blocks += pages; 216 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 217 spin_unlock(&sbinfo->stat_lock); 218 } 219} 220 221static int shmem_reserve_inode(struct super_block *sb) 222{ 223 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 224 if (sbinfo->max_inodes) { 225 spin_lock(&sbinfo->stat_lock); 226 if (!sbinfo->free_inodes) { 227 spin_unlock(&sbinfo->stat_lock); 228 return -ENOSPC; 229 } 230 sbinfo->free_inodes--; 231 spin_unlock(&sbinfo->stat_lock); 232 } 233 return 0; 234} 235 236static void shmem_free_inode(struct super_block *sb) 237{ 238 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 239 if (sbinfo->max_inodes) { 240 spin_lock(&sbinfo->stat_lock); 241 sbinfo->free_inodes++; 242 spin_unlock(&sbinfo->stat_lock); 243 } 244} 245 246/** 247 * shmem_recalc_inode - recalculate the size of an inode 248 * @inode: inode to recalc 249 * 250 * We have to calculate the free blocks since the mm can drop 251 * undirtied hole pages behind our back. 252 * 253 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 254 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 255 * 256 * It has to be called with the spinlock held. 257 */ 258static void shmem_recalc_inode(struct inode *inode) 259{ 260 struct shmem_inode_info *info = SHMEM_I(inode); 261 long freed; 262 263 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 264 if (freed > 0) { 265 info->alloced -= freed; 266 shmem_unacct_blocks(info->flags, freed); 267 shmem_free_blocks(inode, freed); 268 } 269} 270 271/** 272 * shmem_swp_entry - find the swap vector position in the info structure 273 * @info: info structure for the inode 274 * @index: index of the page to find 275 * @page: optional page to add to the structure. Has to be preset to 276 * all zeros 277 * 278 * If there is no space allocated yet it will return NULL when 279 * page is NULL, else it will use the page for the needed block, 280 * setting it to NULL on return to indicate that it has been used. 281 * 282 * The swap vector is organized the following way: 283 * 284 * There are SHMEM_NR_DIRECT entries directly stored in the 285 * shmem_inode_info structure. So small files do not need an addional 286 * allocation. 287 * 288 * For pages with index > SHMEM_NR_DIRECT there is the pointer 289 * i_indirect which points to a page which holds in the first half 290 * doubly indirect blocks, in the second half triple indirect blocks: 291 * 292 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 293 * following layout (for SHMEM_NR_DIRECT == 16): 294 * 295 * i_indirect -> dir --> 16-19 296 * | +-> 20-23 297 * | 298 * +-->dir2 --> 24-27 299 * | +-> 28-31 300 * | +-> 32-35 301 * | +-> 36-39 302 * | 303 * +-->dir3 --> 40-43 304 * +-> 44-47 305 * +-> 48-51 306 * +-> 52-55 307 */ 308static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 309{ 310 unsigned long offset; 311 struct page **dir; 312 struct page *subdir; 313 314 if (index < SHMEM_NR_DIRECT) { 315 shmem_swp_balance_unmap(); 316 return info->i_direct+index; 317 } 318 if (!info->i_indirect) { 319 if (page) { 320 info->i_indirect = *page; 321 *page = NULL; 322 } 323 return NULL; /* need another page */ 324 } 325 326 index -= SHMEM_NR_DIRECT; 327 offset = index % ENTRIES_PER_PAGE; 328 index /= ENTRIES_PER_PAGE; 329 dir = shmem_dir_map(info->i_indirect); 330 331 if (index >= ENTRIES_PER_PAGE/2) { 332 index -= ENTRIES_PER_PAGE/2; 333 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 334 index %= ENTRIES_PER_PAGE; 335 subdir = *dir; 336 if (!subdir) { 337 if (page) { 338 *dir = *page; 339 *page = NULL; 340 } 341 shmem_dir_unmap(dir); 342 return NULL; /* need another page */ 343 } 344 shmem_dir_unmap(dir); 345 dir = shmem_dir_map(subdir); 346 } 347 348 dir += index; 349 subdir = *dir; 350 if (!subdir) { 351 if (!page || !(subdir = *page)) { 352 shmem_dir_unmap(dir); 353 return NULL; /* need a page */ 354 } 355 *dir = subdir; 356 *page = NULL; 357 } 358 shmem_dir_unmap(dir); 359 return shmem_swp_map(subdir) + offset; 360} 361 362static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 363{ 364 long incdec = value? 1: -1; 365 366 entry->val = value; 367 info->swapped += incdec; 368 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 369 struct page *page = kmap_atomic_to_page(entry); 370 set_page_private(page, page_private(page) + incdec); 371 } 372} 373 374/** 375 * shmem_swp_alloc - get the position of the swap entry for the page. 376 * @info: info structure for the inode 377 * @index: index of the page to find 378 * @sgp: check and recheck i_size? skip allocation? 379 * 380 * If the entry does not exist, allocate it. 381 */ 382static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 383{ 384 struct inode *inode = &info->vfs_inode; 385 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 386 struct page *page = NULL; 387 swp_entry_t *entry; 388 389 if (sgp != SGP_WRITE && 390 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 391 return ERR_PTR(-EINVAL); 392 393 while (!(entry = shmem_swp_entry(info, index, &page))) { 394 if (sgp == SGP_READ) 395 return shmem_swp_map(ZERO_PAGE(0)); 396 /* 397 * Test free_blocks against 1 not 0, since we have 1 data 398 * page (and perhaps indirect index pages) yet to allocate: 399 * a waste to allocate index if we cannot allocate data. 400 */ 401 if (sbinfo->max_blocks) { 402 spin_lock(&sbinfo->stat_lock); 403 if (sbinfo->free_blocks <= 1) { 404 spin_unlock(&sbinfo->stat_lock); 405 return ERR_PTR(-ENOSPC); 406 } 407 sbinfo->free_blocks--; 408 inode->i_blocks += BLOCKS_PER_PAGE; 409 spin_unlock(&sbinfo->stat_lock); 410 } 411 412 spin_unlock(&info->lock); 413 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); 414 if (page) 415 set_page_private(page, 0); 416 spin_lock(&info->lock); 417 418 if (!page) { 419 shmem_free_blocks(inode, 1); 420 return ERR_PTR(-ENOMEM); 421 } 422 if (sgp != SGP_WRITE && 423 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 424 entry = ERR_PTR(-EINVAL); 425 break; 426 } 427 if (info->next_index <= index) 428 info->next_index = index + 1; 429 } 430 if (page) { 431 /* another task gave its page, or truncated the file */ 432 shmem_free_blocks(inode, 1); 433 shmem_dir_free(page); 434 } 435 if (info->next_index <= index && !IS_ERR(entry)) 436 info->next_index = index + 1; 437 return entry; 438} 439 440/** 441 * shmem_free_swp - free some swap entries in a directory 442 * @dir: pointer to the directory 443 * @edir: pointer after last entry of the directory 444 * @punch_lock: pointer to spinlock when needed for the holepunch case 445 */ 446static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, 447 spinlock_t *punch_lock) 448{ 449 spinlock_t *punch_unlock = NULL; 450 swp_entry_t *ptr; 451 int freed = 0; 452 453 for (ptr = dir; ptr < edir; ptr++) { 454 if (ptr->val) { 455 if (unlikely(punch_lock)) { 456 punch_unlock = punch_lock; 457 punch_lock = NULL; 458 spin_lock(punch_unlock); 459 if (!ptr->val) 460 continue; 461 } 462 free_swap_and_cache(*ptr); 463 *ptr = (swp_entry_t){0}; 464 freed++; 465 } 466 } 467 if (punch_unlock) 468 spin_unlock(punch_unlock); 469 return freed; 470} 471 472static int shmem_map_and_free_swp(struct page *subdir, int offset, 473 int limit, struct page ***dir, spinlock_t *punch_lock) 474{ 475 swp_entry_t *ptr; 476 int freed = 0; 477 478 ptr = shmem_swp_map(subdir); 479 for (; offset < limit; offset += LATENCY_LIMIT) { 480 int size = limit - offset; 481 if (size > LATENCY_LIMIT) 482 size = LATENCY_LIMIT; 483 freed += shmem_free_swp(ptr+offset, ptr+offset+size, 484 punch_lock); 485 if (need_resched()) { 486 shmem_swp_unmap(ptr); 487 if (*dir) { 488 shmem_dir_unmap(*dir); 489 *dir = NULL; 490 } 491 cond_resched(); 492 ptr = shmem_swp_map(subdir); 493 } 494 } 495 shmem_swp_unmap(ptr); 496 return freed; 497} 498 499static void shmem_free_pages(struct list_head *next) 500{ 501 struct page *page; 502 int freed = 0; 503 504 do { 505 page = container_of(next, struct page, lru); 506 next = next->next; 507 shmem_dir_free(page); 508 freed++; 509 if (freed >= LATENCY_LIMIT) { 510 cond_resched(); 511 freed = 0; 512 } 513 } while (next); 514} 515 516static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 517{ 518 struct shmem_inode_info *info = SHMEM_I(inode); 519 unsigned long idx; 520 unsigned long size; 521 unsigned long limit; 522 unsigned long stage; 523 unsigned long diroff; 524 struct page **dir; 525 struct page *topdir; 526 struct page *middir; 527 struct page *subdir; 528 swp_entry_t *ptr; 529 LIST_HEAD(pages_to_free); 530 long nr_pages_to_free = 0; 531 long nr_swaps_freed = 0; 532 int offset; 533 int freed; 534 int punch_hole; 535 spinlock_t *needs_lock; 536 spinlock_t *punch_lock; 537 unsigned long upper_limit; 538 539 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 540 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 541 if (idx >= info->next_index) 542 return; 543 544 spin_lock(&info->lock); 545 info->flags |= SHMEM_TRUNCATE; 546 if (likely(end == (loff_t) -1)) { 547 limit = info->next_index; 548 upper_limit = SHMEM_MAX_INDEX; 549 info->next_index = idx; 550 needs_lock = NULL; 551 punch_hole = 0; 552 } else { 553 if (end + 1 >= inode->i_size) { /* we may free a little more */ 554 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> 555 PAGE_CACHE_SHIFT; 556 upper_limit = SHMEM_MAX_INDEX; 557 } else { 558 limit = (end + 1) >> PAGE_CACHE_SHIFT; 559 upper_limit = limit; 560 } 561 needs_lock = &info->lock; 562 punch_hole = 1; 563 } 564 565 topdir = info->i_indirect; 566 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 567 info->i_indirect = NULL; 568 nr_pages_to_free++; 569 list_add(&topdir->lru, &pages_to_free); 570 } 571 spin_unlock(&info->lock); 572 573 if (info->swapped && idx < SHMEM_NR_DIRECT) { 574 ptr = info->i_direct; 575 size = limit; 576 if (size > SHMEM_NR_DIRECT) 577 size = SHMEM_NR_DIRECT; 578 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); 579 } 580 581 /* 582 * If there are no indirect blocks or we are punching a hole 583 * below indirect blocks, nothing to be done. 584 */ 585 if (!topdir || limit <= SHMEM_NR_DIRECT) 586 goto done2; 587 588 /* 589 * The truncation case has already dropped info->lock, and we're safe 590 * because i_size and next_index have already been lowered, preventing 591 * access beyond. But in the punch_hole case, we still need to take 592 * the lock when updating the swap directory, because there might be 593 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or 594 * shmem_writepage. However, whenever we find we can remove a whole 595 * directory page (not at the misaligned start or end of the range), 596 * we first NULLify its pointer in the level above, and then have no 597 * need to take the lock when updating its contents: needs_lock and 598 * punch_lock (either pointing to info->lock or NULL) manage this. 599 */ 600 601 upper_limit -= SHMEM_NR_DIRECT; 602 limit -= SHMEM_NR_DIRECT; 603 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 604 offset = idx % ENTRIES_PER_PAGE; 605 idx -= offset; 606 607 dir = shmem_dir_map(topdir); 608 stage = ENTRIES_PER_PAGEPAGE/2; 609 if (idx < ENTRIES_PER_PAGEPAGE/2) { 610 middir = topdir; 611 diroff = idx/ENTRIES_PER_PAGE; 612 } else { 613 dir += ENTRIES_PER_PAGE/2; 614 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 615 while (stage <= idx) 616 stage += ENTRIES_PER_PAGEPAGE; 617 middir = *dir; 618 if (*dir) { 619 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 620 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 621 if (!diroff && !offset && upper_limit >= stage) { 622 if (needs_lock) { 623 spin_lock(needs_lock); 624 *dir = NULL; 625 spin_unlock(needs_lock); 626 needs_lock = NULL; 627 } else 628 *dir = NULL; 629 nr_pages_to_free++; 630 list_add(&middir->lru, &pages_to_free); 631 } 632 shmem_dir_unmap(dir); 633 dir = shmem_dir_map(middir); 634 } else { 635 diroff = 0; 636 offset = 0; 637 idx = stage; 638 } 639 } 640 641 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 642 if (unlikely(idx == stage)) { 643 shmem_dir_unmap(dir); 644 dir = shmem_dir_map(topdir) + 645 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 646 while (!*dir) { 647 dir++; 648 idx += ENTRIES_PER_PAGEPAGE; 649 if (idx >= limit) 650 goto done1; 651 } 652 stage = idx + ENTRIES_PER_PAGEPAGE; 653 middir = *dir; 654 if (punch_hole) 655 needs_lock = &info->lock; 656 if (upper_limit >= stage) { 657 if (needs_lock) { 658 spin_lock(needs_lock); 659 *dir = NULL; 660 spin_unlock(needs_lock); 661 needs_lock = NULL; 662 } else 663 *dir = NULL; 664 nr_pages_to_free++; 665 list_add(&middir->lru, &pages_to_free); 666 } 667 shmem_dir_unmap(dir); 668 cond_resched(); 669 dir = shmem_dir_map(middir); 670 diroff = 0; 671 } 672 punch_lock = needs_lock; 673 subdir = dir[diroff]; 674 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { 675 if (needs_lock) { 676 spin_lock(needs_lock); 677 dir[diroff] = NULL; 678 spin_unlock(needs_lock); 679 punch_lock = NULL; 680 } else 681 dir[diroff] = NULL; 682 nr_pages_to_free++; 683 list_add(&subdir->lru, &pages_to_free); 684 } 685 if (subdir && page_private(subdir) /* has swap entries */) { 686 size = limit - idx; 687 if (size > ENTRIES_PER_PAGE) 688 size = ENTRIES_PER_PAGE; 689 freed = shmem_map_and_free_swp(subdir, 690 offset, size, &dir, punch_lock); 691 if (!dir) 692 dir = shmem_dir_map(middir); 693 nr_swaps_freed += freed; 694 if (offset || punch_lock) { 695 spin_lock(&info->lock); 696 set_page_private(subdir, 697 page_private(subdir) - freed); 698 spin_unlock(&info->lock); 699 } else 700 BUG_ON(page_private(subdir) != freed); 701 } 702 offset = 0; 703 } 704done1: 705 shmem_dir_unmap(dir); 706done2: 707 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 708 /* 709 * Call truncate_inode_pages again: racing shmem_unuse_inode 710 * may have swizzled a page in from swap since vmtruncate or 711 * generic_delete_inode did it, before we lowered next_index. 712 * Also, though shmem_getpage checks i_size before adding to 713 * cache, no recheck after: so fix the narrow window there too. 714 * 715 * Recalling truncate_inode_pages_range and unmap_mapping_range 716 * every time for punch_hole (which never got a chance to clear 717 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 718 * yet hardly ever necessary: try to optimize them out later. 719 */ 720 truncate_inode_pages_range(inode->i_mapping, start, end); 721 if (punch_hole) 722 unmap_mapping_range(inode->i_mapping, start, 723 end - start, 1); 724 } 725 726 spin_lock(&info->lock); 727 info->flags &= ~SHMEM_TRUNCATE; 728 info->swapped -= nr_swaps_freed; 729 if (nr_pages_to_free) 730 shmem_free_blocks(inode, nr_pages_to_free); 731 shmem_recalc_inode(inode); 732 spin_unlock(&info->lock); 733 734 /* 735 * Empty swap vector directory pages to be freed? 736 */ 737 if (!list_empty(&pages_to_free)) { 738 pages_to_free.prev->next = NULL; 739 shmem_free_pages(pages_to_free.next); 740 } 741} 742 743static void shmem_truncate(struct inode *inode) 744{ 745 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 746} 747 748static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 749{ 750 struct inode *inode = dentry->d_inode; 751 struct page *page = NULL; 752 int error; 753 754 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 755 if (attr->ia_size < inode->i_size) { 756 /* 757 * If truncating down to a partial page, then 758 * if that page is already allocated, hold it 759 * in memory until the truncation is over, so 760 * truncate_partial_page cannnot miss it were 761 * it assigned to swap. 762 */ 763 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 764 (void) shmem_getpage(inode, 765 attr->ia_size>>PAGE_CACHE_SHIFT, 766 &page, SGP_READ, NULL); 767 if (page) 768 unlock_page(page); 769 } 770 /* 771 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 772 * detect if any pages might have been added to cache 773 * after truncate_inode_pages. But we needn't bother 774 * if it's being fully truncated to zero-length: the 775 * nrpages check is efficient enough in that case. 776 */ 777 if (attr->ia_size) { 778 struct shmem_inode_info *info = SHMEM_I(inode); 779 spin_lock(&info->lock); 780 info->flags &= ~SHMEM_PAGEIN; 781 spin_unlock(&info->lock); 782 } 783 } 784 } 785 786 error = inode_change_ok(inode, attr); 787 if (!error) 788 error = inode_setattr(inode, attr); 789#ifdef CONFIG_TMPFS_POSIX_ACL 790 if (!error && (attr->ia_valid & ATTR_MODE)) 791 error = generic_acl_chmod(inode, &shmem_acl_ops); 792#endif 793 if (page) 794 page_cache_release(page); 795 return error; 796} 797 798static void shmem_delete_inode(struct inode *inode) 799{ 800 struct shmem_inode_info *info = SHMEM_I(inode); 801 802 if (inode->i_op->truncate == shmem_truncate) { 803 truncate_inode_pages(inode->i_mapping, 0); 804 shmem_unacct_size(info->flags, inode->i_size); 805 inode->i_size = 0; 806 shmem_truncate(inode); 807 if (!list_empty(&info->swaplist)) { 808 mutex_lock(&shmem_swaplist_mutex); 809 list_del_init(&info->swaplist); 810 mutex_unlock(&shmem_swaplist_mutex); 811 } 812 } 813 BUG_ON(inode->i_blocks); 814 shmem_free_inode(inode->i_sb); 815 clear_inode(inode); 816} 817 818static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 819{ 820 swp_entry_t *ptr; 821 822 for (ptr = dir; ptr < edir; ptr++) { 823 if (ptr->val == entry.val) 824 return ptr - dir; 825 } 826 return -1; 827} 828 829static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 830{ 831 struct inode *inode; 832 unsigned long idx; 833 unsigned long size; 834 unsigned long limit; 835 unsigned long stage; 836 struct page **dir; 837 struct page *subdir; 838 swp_entry_t *ptr; 839 int offset; 840 int error; 841 842 idx = 0; 843 ptr = info->i_direct; 844 spin_lock(&info->lock); 845 if (!info->swapped) { 846 list_del_init(&info->swaplist); 847 goto lost2; 848 } 849 limit = info->next_index; 850 size = limit; 851 if (size > SHMEM_NR_DIRECT) 852 size = SHMEM_NR_DIRECT; 853 offset = shmem_find_swp(entry, ptr, ptr+size); 854 if (offset >= 0) 855 goto found; 856 if (!info->i_indirect) 857 goto lost2; 858 859 dir = shmem_dir_map(info->i_indirect); 860 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 861 862 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 863 if (unlikely(idx == stage)) { 864 shmem_dir_unmap(dir-1); 865 if (cond_resched_lock(&info->lock)) { 866 /* check it has not been truncated */ 867 if (limit > info->next_index) { 868 limit = info->next_index; 869 if (idx >= limit) 870 goto lost2; 871 } 872 } 873 dir = shmem_dir_map(info->i_indirect) + 874 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 875 while (!*dir) { 876 dir++; 877 idx += ENTRIES_PER_PAGEPAGE; 878 if (idx >= limit) 879 goto lost1; 880 } 881 stage = idx + ENTRIES_PER_PAGEPAGE; 882 subdir = *dir; 883 shmem_dir_unmap(dir); 884 dir = shmem_dir_map(subdir); 885 } 886 subdir = *dir; 887 if (subdir && page_private(subdir)) { 888 ptr = shmem_swp_map(subdir); 889 size = limit - idx; 890 if (size > ENTRIES_PER_PAGE) 891 size = ENTRIES_PER_PAGE; 892 offset = shmem_find_swp(entry, ptr, ptr+size); 893 shmem_swp_unmap(ptr); 894 if (offset >= 0) { 895 shmem_dir_unmap(dir); 896 goto found; 897 } 898 } 899 } 900lost1: 901 shmem_dir_unmap(dir-1); 902lost2: 903 spin_unlock(&info->lock); 904 return 0; 905found: 906 idx += offset; 907 inode = igrab(&info->vfs_inode); 908 spin_unlock(&info->lock); 909 910 /* 911 * Move _head_ to start search for next from here. 912 * But be careful: shmem_delete_inode checks list_empty without taking 913 * mutex, and there's an instant in list_move_tail when info->swaplist 914 * would appear empty, if it were the only one on shmem_swaplist. We 915 * could avoid doing it if inode NULL; or use this minor optimization. 916 */ 917 if (shmem_swaplist.next != &info->swaplist) 918 list_move_tail(&shmem_swaplist, &info->swaplist); 919 mutex_unlock(&shmem_swaplist_mutex); 920 921 error = 1; 922 if (!inode) 923 goto out; 924 /* Precharge page using GFP_KERNEL while we can wait */ 925 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); 926 if (error) 927 goto out; 928 error = radix_tree_preload(GFP_KERNEL); 929 if (error) { 930 mem_cgroup_uncharge_cache_page(page); 931 goto out; 932 } 933 error = 1; 934 935 spin_lock(&info->lock); 936 ptr = shmem_swp_entry(info, idx, NULL); 937 if (ptr && ptr->val == entry.val) { 938 error = add_to_page_cache_locked(page, inode->i_mapping, 939 idx, GFP_NOWAIT); 940 /* does mem_cgroup_uncharge_cache_page on error */ 941 } else /* we must compensate for our precharge above */ 942 mem_cgroup_uncharge_cache_page(page); 943 944 if (error == -EEXIST) { 945 struct page *filepage = find_get_page(inode->i_mapping, idx); 946 error = 1; 947 if (filepage) { 948 /* 949 * There might be a more uptodate page coming down 950 * from a stacked writepage: forget our swappage if so. 951 */ 952 if (PageUptodate(filepage)) 953 error = 0; 954 page_cache_release(filepage); 955 } 956 } 957 if (!error) { 958 delete_from_swap_cache(page); 959 set_page_dirty(page); 960 info->flags |= SHMEM_PAGEIN; 961 shmem_swp_set(info, ptr, 0); 962 swap_free(entry); 963 error = 1; /* not an error, but entry was found */ 964 } 965 if (ptr) 966 shmem_swp_unmap(ptr); 967 spin_unlock(&info->lock); 968 radix_tree_preload_end(); 969out: 970 unlock_page(page); 971 page_cache_release(page); 972 iput(inode); /* allows for NULL */ 973 return error; 974} 975 976/* 977 * shmem_unuse() search for an eventually swapped out shmem page. 978 */ 979int shmem_unuse(swp_entry_t entry, struct page *page) 980{ 981 struct list_head *p, *next; 982 struct shmem_inode_info *info; 983 int found = 0; 984 985 mutex_lock(&shmem_swaplist_mutex); 986 list_for_each_safe(p, next, &shmem_swaplist) { 987 info = list_entry(p, struct shmem_inode_info, swaplist); 988 found = shmem_unuse_inode(info, entry, page); 989 cond_resched(); 990 if (found) 991 goto out; 992 } 993 mutex_unlock(&shmem_swaplist_mutex); 994out: return found; /* 0 or 1 or -ENOMEM */ 995} 996 997/* 998 * Move the page from the page cache to the swap cache. 999 */ 1000static int shmem_writepage(struct page *page, struct writeback_control *wbc) 1001{ 1002 struct shmem_inode_info *info; 1003 swp_entry_t *entry, swap; 1004 struct address_space *mapping; 1005 unsigned long index; 1006 struct inode *inode; 1007 1008 BUG_ON(!PageLocked(page)); 1009 mapping = page->mapping; 1010 index = page->index; 1011 inode = mapping->host; 1012 info = SHMEM_I(inode); 1013 if (info->flags & VM_LOCKED) 1014 goto redirty; 1015 if (!total_swap_pages) 1016 goto redirty; 1017 1018 /* 1019 * shmem_backing_dev_info's capabilities prevent regular writeback or 1020 * sync from ever calling shmem_writepage; but a stacking filesystem 1021 * may use the ->writepage of its underlying filesystem, in which case 1022 * tmpfs should write out to swap only in response to memory pressure, 1023 * and not for pdflush or sync. However, in those cases, we do still 1024 * want to check if there's a redundant swappage to be discarded. 1025 */ 1026 if (wbc->for_reclaim) 1027 swap = get_swap_page(); 1028 else 1029 swap.val = 0; 1030 1031 spin_lock(&info->lock); 1032 if (index >= info->next_index) { 1033 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1034 goto unlock; 1035 } 1036 entry = shmem_swp_entry(info, index, NULL); 1037 if (entry->val) { 1038 /* 1039 * The more uptodate page coming down from a stacked 1040 * writepage should replace our old swappage. 1041 */ 1042 free_swap_and_cache(*entry); 1043 shmem_swp_set(info, entry, 0); 1044 } 1045 shmem_recalc_inode(inode); 1046 1047 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1048 remove_from_page_cache(page); 1049 shmem_swp_set(info, entry, swap.val); 1050 shmem_swp_unmap(entry); 1051 if (list_empty(&info->swaplist)) 1052 inode = igrab(inode); 1053 else 1054 inode = NULL; 1055 spin_unlock(&info->lock); 1056 swap_duplicate(swap); 1057 BUG_ON(page_mapped(page)); 1058 page_cache_release(page); /* pagecache ref */ 1059 set_page_dirty(page); 1060 unlock_page(page); 1061 if (inode) { 1062 mutex_lock(&shmem_swaplist_mutex); 1063 /* move instead of add in case we're racing */ 1064 list_move_tail(&info->swaplist, &shmem_swaplist); 1065 mutex_unlock(&shmem_swaplist_mutex); 1066 iput(inode); 1067 } 1068 return 0; 1069 } 1070 1071 shmem_swp_unmap(entry); 1072unlock: 1073 spin_unlock(&info->lock); 1074 swap_free(swap); 1075redirty: 1076 set_page_dirty(page); 1077 if (wbc->for_reclaim) 1078 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1079 unlock_page(page); 1080 return 0; 1081} 1082 1083#ifdef CONFIG_NUMA 1084#ifdef CONFIG_TMPFS 1085static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) 1086{ 1087 char buffer[64]; 1088 1089 if (!mpol || mpol->mode == MPOL_DEFAULT) 1090 return; /* show nothing */ 1091 1092 mpol_to_str(buffer, sizeof(buffer), mpol, 1); 1093 1094 seq_printf(seq, ",mpol=%s", buffer); 1095} 1096 1097static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1098{ 1099 struct mempolicy *mpol = NULL; 1100 if (sbinfo->mpol) { 1101 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ 1102 mpol = sbinfo->mpol; 1103 mpol_get(mpol); 1104 spin_unlock(&sbinfo->stat_lock); 1105 } 1106 return mpol; 1107} 1108#endif /* CONFIG_TMPFS */ 1109 1110static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1111 struct shmem_inode_info *info, unsigned long idx) 1112{ 1113 struct mempolicy mpol, *spol; 1114 struct vm_area_struct pvma; 1115 struct page *page; 1116 1117 spol = mpol_cond_copy(&mpol, 1118 mpol_shared_policy_lookup(&info->policy, idx)); 1119 1120 /* Create a pseudo vma that just contains the policy */ 1121 pvma.vm_start = 0; 1122 pvma.vm_pgoff = idx; 1123 pvma.vm_ops = NULL; 1124 pvma.vm_policy = spol; 1125 page = swapin_readahead(entry, gfp, &pvma, 0); 1126 return page; 1127} 1128 1129static struct page *shmem_alloc_page(gfp_t gfp, 1130 struct shmem_inode_info *info, unsigned long idx) 1131{ 1132 struct vm_area_struct pvma; 1133 1134 /* Create a pseudo vma that just contains the policy */ 1135 pvma.vm_start = 0; 1136 pvma.vm_pgoff = idx; 1137 pvma.vm_ops = NULL; 1138 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1139 1140 /* 1141 * alloc_page_vma() will drop the shared policy reference 1142 */ 1143 return alloc_page_vma(gfp, &pvma, 0); 1144} 1145#else /* !CONFIG_NUMA */ 1146#ifdef CONFIG_TMPFS 1147static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) 1148{ 1149} 1150#endif /* CONFIG_TMPFS */ 1151 1152static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1153 struct shmem_inode_info *info, unsigned long idx) 1154{ 1155 return swapin_readahead(entry, gfp, NULL, 0); 1156} 1157 1158static inline struct page *shmem_alloc_page(gfp_t gfp, 1159 struct shmem_inode_info *info, unsigned long idx) 1160{ 1161 return alloc_page(gfp); 1162} 1163#endif /* CONFIG_NUMA */ 1164 1165#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) 1166static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1167{ 1168 return NULL; 1169} 1170#endif 1171 1172/* 1173 * shmem_getpage - either get the page from swap or allocate a new one 1174 * 1175 * If we allocate a new one we do not mark it dirty. That's up to the 1176 * vm. If we swap it in we mark it dirty since we also free the swap 1177 * entry since a page cannot live in both the swap and page cache 1178 */ 1179static int shmem_getpage(struct inode *inode, unsigned long idx, 1180 struct page **pagep, enum sgp_type sgp, int *type) 1181{ 1182 struct address_space *mapping = inode->i_mapping; 1183 struct shmem_inode_info *info = SHMEM_I(inode); 1184 struct shmem_sb_info *sbinfo; 1185 struct page *filepage = *pagep; 1186 struct page *swappage; 1187 swp_entry_t *entry; 1188 swp_entry_t swap; 1189 gfp_t gfp; 1190 int error; 1191 1192 if (idx >= SHMEM_MAX_INDEX) 1193 return -EFBIG; 1194 1195 if (type) 1196 *type = 0; 1197 1198 /* 1199 * Normally, filepage is NULL on entry, and either found 1200 * uptodate immediately, or allocated and zeroed, or read 1201 * in under swappage, which is then assigned to filepage. 1202 * But shmem_readpage (required for splice) passes in a locked 1203 * filepage, which may be found not uptodate by other callers 1204 * too, and may need to be copied from the swappage read in. 1205 */ 1206repeat: 1207 if (!filepage) 1208 filepage = find_lock_page(mapping, idx); 1209 if (filepage && PageUptodate(filepage)) 1210 goto done; 1211 error = 0; 1212 gfp = mapping_gfp_mask(mapping); 1213 if (!filepage) { 1214 /* 1215 * Try to preload while we can wait, to not make a habit of 1216 * draining atomic reserves; but don't latch on to this cpu. 1217 */ 1218 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1219 if (error) 1220 goto failed; 1221 radix_tree_preload_end(); 1222 } 1223 1224 spin_lock(&info->lock); 1225 shmem_recalc_inode(inode); 1226 entry = shmem_swp_alloc(info, idx, sgp); 1227 if (IS_ERR(entry)) { 1228 spin_unlock(&info->lock); 1229 error = PTR_ERR(entry); 1230 goto failed; 1231 } 1232 swap = *entry; 1233 1234 if (swap.val) { 1235 /* Look it up and read it in.. */ 1236 swappage = lookup_swap_cache(swap); 1237 if (!swappage) { 1238 shmem_swp_unmap(entry); 1239 /* here we actually do the io */ 1240 if (type && !(*type & VM_FAULT_MAJOR)) { 1241 __count_vm_event(PGMAJFAULT); 1242 *type |= VM_FAULT_MAJOR; 1243 } 1244 spin_unlock(&info->lock); 1245 swappage = shmem_swapin(swap, gfp, info, idx); 1246 if (!swappage) { 1247 spin_lock(&info->lock); 1248 entry = shmem_swp_alloc(info, idx, sgp); 1249 if (IS_ERR(entry)) 1250 error = PTR_ERR(entry); 1251 else { 1252 if (entry->val == swap.val) 1253 error = -ENOMEM; 1254 shmem_swp_unmap(entry); 1255 } 1256 spin_unlock(&info->lock); 1257 if (error) 1258 goto failed; 1259 goto repeat; 1260 } 1261 wait_on_page_locked(swappage); 1262 page_cache_release(swappage); 1263 goto repeat; 1264 } 1265 1266 /* We have to do this with page locked to prevent races */ 1267 if (!trylock_page(swappage)) { 1268 shmem_swp_unmap(entry); 1269 spin_unlock(&info->lock); 1270 wait_on_page_locked(swappage); 1271 page_cache_release(swappage); 1272 goto repeat; 1273 } 1274 if (PageWriteback(swappage)) { 1275 shmem_swp_unmap(entry); 1276 spin_unlock(&info->lock); 1277 wait_on_page_writeback(swappage); 1278 unlock_page(swappage); 1279 page_cache_release(swappage); 1280 goto repeat; 1281 } 1282 if (!PageUptodate(swappage)) { 1283 shmem_swp_unmap(entry); 1284 spin_unlock(&info->lock); 1285 unlock_page(swappage); 1286 page_cache_release(swappage); 1287 error = -EIO; 1288 goto failed; 1289 } 1290 1291 if (filepage) { 1292 shmem_swp_set(info, entry, 0); 1293 shmem_swp_unmap(entry); 1294 delete_from_swap_cache(swappage); 1295 spin_unlock(&info->lock); 1296 copy_highpage(filepage, swappage); 1297 unlock_page(swappage); 1298 page_cache_release(swappage); 1299 flush_dcache_page(filepage); 1300 SetPageUptodate(filepage); 1301 set_page_dirty(filepage); 1302 swap_free(swap); 1303 } else if (!(error = add_to_page_cache_locked(swappage, mapping, 1304 idx, GFP_NOWAIT))) { 1305 info->flags |= SHMEM_PAGEIN; 1306 shmem_swp_set(info, entry, 0); 1307 shmem_swp_unmap(entry); 1308 delete_from_swap_cache(swappage); 1309 spin_unlock(&info->lock); 1310 filepage = swappage; 1311 set_page_dirty(filepage); 1312 swap_free(swap); 1313 } else { 1314 shmem_swp_unmap(entry); 1315 spin_unlock(&info->lock); 1316 unlock_page(swappage); 1317 page_cache_release(swappage); 1318 if (error == -ENOMEM) { 1319 /* allow reclaim from this memory cgroup */ 1320 error = mem_cgroup_shrink_usage(current->mm, 1321 gfp); 1322 if (error) 1323 goto failed; 1324 } 1325 goto repeat; 1326 } 1327 } else if (sgp == SGP_READ && !filepage) { 1328 shmem_swp_unmap(entry); 1329 filepage = find_get_page(mapping, idx); 1330 if (filepage && 1331 (!PageUptodate(filepage) || !trylock_page(filepage))) { 1332 spin_unlock(&info->lock); 1333 wait_on_page_locked(filepage); 1334 page_cache_release(filepage); 1335 filepage = NULL; 1336 goto repeat; 1337 } 1338 spin_unlock(&info->lock); 1339 } else { 1340 shmem_swp_unmap(entry); 1341 sbinfo = SHMEM_SB(inode->i_sb); 1342 if (sbinfo->max_blocks) { 1343 spin_lock(&sbinfo->stat_lock); 1344 if (sbinfo->free_blocks == 0 || 1345 shmem_acct_block(info->flags)) { 1346 spin_unlock(&sbinfo->stat_lock); 1347 spin_unlock(&info->lock); 1348 error = -ENOSPC; 1349 goto failed; 1350 } 1351 sbinfo->free_blocks--; 1352 inode->i_blocks += BLOCKS_PER_PAGE; 1353 spin_unlock(&sbinfo->stat_lock); 1354 } else if (shmem_acct_block(info->flags)) { 1355 spin_unlock(&info->lock); 1356 error = -ENOSPC; 1357 goto failed; 1358 } 1359 1360 if (!filepage) { 1361 int ret; 1362 1363 spin_unlock(&info->lock); 1364 filepage = shmem_alloc_page(gfp, info, idx); 1365 if (!filepage) { 1366 shmem_unacct_blocks(info->flags, 1); 1367 shmem_free_blocks(inode, 1); 1368 error = -ENOMEM; 1369 goto failed; 1370 } 1371 SetPageSwapBacked(filepage); 1372 1373 /* Precharge page while we can wait, compensate after */ 1374 error = mem_cgroup_cache_charge(filepage, current->mm, 1375 gfp & ~__GFP_HIGHMEM); 1376 if (error) { 1377 page_cache_release(filepage); 1378 shmem_unacct_blocks(info->flags, 1); 1379 shmem_free_blocks(inode, 1); 1380 filepage = NULL; 1381 goto failed; 1382 } 1383 1384 spin_lock(&info->lock); 1385 entry = shmem_swp_alloc(info, idx, sgp); 1386 if (IS_ERR(entry)) 1387 error = PTR_ERR(entry); 1388 else { 1389 swap = *entry; 1390 shmem_swp_unmap(entry); 1391 } 1392 ret = error || swap.val; 1393 if (ret) 1394 mem_cgroup_uncharge_cache_page(filepage); 1395 else 1396 ret = add_to_page_cache_lru(filepage, mapping, 1397 idx, GFP_NOWAIT); 1398 /* 1399 * At add_to_page_cache_lru() failure, uncharge will 1400 * be done automatically. 1401 */ 1402 if (ret) { 1403 spin_unlock(&info->lock); 1404 page_cache_release(filepage); 1405 shmem_unacct_blocks(info->flags, 1); 1406 shmem_free_blocks(inode, 1); 1407 filepage = NULL; 1408 if (error) 1409 goto failed; 1410 goto repeat; 1411 } 1412 info->flags |= SHMEM_PAGEIN; 1413 } 1414 1415 info->alloced++; 1416 spin_unlock(&info->lock); 1417 clear_highpage(filepage); 1418 flush_dcache_page(filepage); 1419 SetPageUptodate(filepage); 1420 if (sgp == SGP_DIRTY) 1421 set_page_dirty(filepage); 1422 } 1423done: 1424 *pagep = filepage; 1425 return 0; 1426 1427failed: 1428 if (*pagep != filepage) { 1429 unlock_page(filepage); 1430 page_cache_release(filepage); 1431 } 1432 return error; 1433} 1434 1435static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1436{ 1437 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1438 int error; 1439 int ret; 1440 1441 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1442 return VM_FAULT_SIGBUS; 1443 1444 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1445 if (error) 1446 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1447 1448 mark_page_accessed(vmf->page); 1449 return ret | VM_FAULT_LOCKED; 1450} 1451 1452#ifdef CONFIG_NUMA 1453static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1454{ 1455 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1456 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1457} 1458 1459static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1460 unsigned long addr) 1461{ 1462 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1463 unsigned long idx; 1464 1465 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1466 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1467} 1468#endif 1469 1470int shmem_lock(struct file *file, int lock, struct user_struct *user) 1471{ 1472 struct inode *inode = file->f_path.dentry->d_inode; 1473 struct shmem_inode_info *info = SHMEM_I(inode); 1474 int retval = -ENOMEM; 1475 1476 spin_lock(&info->lock); 1477 if (lock && !(info->flags & VM_LOCKED)) { 1478 if (!user_shm_lock(inode->i_size, user)) 1479 goto out_nomem; 1480 info->flags |= VM_LOCKED; 1481 mapping_set_unevictable(file->f_mapping); 1482 } 1483 if (!lock && (info->flags & VM_LOCKED) && user) { 1484 user_shm_unlock(inode->i_size, user); 1485 info->flags &= ~VM_LOCKED; 1486 mapping_clear_unevictable(file->f_mapping); 1487 scan_mapping_unevictable_pages(file->f_mapping); 1488 } 1489 retval = 0; 1490 1491out_nomem: 1492 spin_unlock(&info->lock); 1493 return retval; 1494} 1495 1496static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1497{ 1498 file_accessed(file); 1499 vma->vm_ops = &shmem_vm_ops; 1500 vma->vm_flags |= VM_CAN_NONLINEAR; 1501 return 0; 1502} 1503 1504static struct inode * 1505shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1506{ 1507 struct inode *inode; 1508 struct shmem_inode_info *info; 1509 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1510 1511 if (shmem_reserve_inode(sb)) 1512 return NULL; 1513 1514 inode = new_inode(sb); 1515 if (inode) { 1516 inode->i_mode = mode; 1517 inode->i_uid = current_fsuid(); 1518 inode->i_gid = current_fsgid(); 1519 inode->i_blocks = 0; 1520 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1521 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1522 inode->i_generation = get_seconds(); 1523 info = SHMEM_I(inode); 1524 memset(info, 0, (char *)inode - (char *)info); 1525 spin_lock_init(&info->lock); 1526 INIT_LIST_HEAD(&info->swaplist); 1527 1528 switch (mode & S_IFMT) { 1529 default: 1530 inode->i_op = &shmem_special_inode_operations; 1531 init_special_inode(inode, mode, dev); 1532 break; 1533 case S_IFREG: 1534 inode->i_mapping->a_ops = &shmem_aops; 1535 inode->i_op = &shmem_inode_operations; 1536 inode->i_fop = &shmem_file_operations; 1537 mpol_shared_policy_init(&info->policy, 1538 shmem_get_sbmpol(sbinfo)); 1539 break; 1540 case S_IFDIR: 1541 inc_nlink(inode); 1542 /* Some things misbehave if size == 0 on a directory */ 1543 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1544 inode->i_op = &shmem_dir_inode_operations; 1545 inode->i_fop = &simple_dir_operations; 1546 break; 1547 case S_IFLNK: 1548 /* 1549 * Must not load anything in the rbtree, 1550 * mpol_free_shared_policy will not be called. 1551 */ 1552 mpol_shared_policy_init(&info->policy, NULL); 1553 break; 1554 } 1555 } else 1556 shmem_free_inode(sb); 1557 return inode; 1558} 1559 1560#ifdef CONFIG_TMPFS 1561static const struct inode_operations shmem_symlink_inode_operations; 1562static const struct inode_operations shmem_symlink_inline_operations; 1563 1564/* 1565 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1566 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1567 * below the loop driver, in the generic fashion that many filesystems support. 1568 */ 1569static int shmem_readpage(struct file *file, struct page *page) 1570{ 1571 struct inode *inode = page->mapping->host; 1572 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1573 unlock_page(page); 1574 return error; 1575} 1576 1577static int 1578shmem_write_begin(struct file *file, struct address_space *mapping, 1579 loff_t pos, unsigned len, unsigned flags, 1580 struct page **pagep, void **fsdata) 1581{ 1582 struct inode *inode = mapping->host; 1583 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1584 *pagep = NULL; 1585 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1586} 1587 1588static int 1589shmem_write_end(struct file *file, struct address_space *mapping, 1590 loff_t pos, unsigned len, unsigned copied, 1591 struct page *page, void *fsdata) 1592{ 1593 struct inode *inode = mapping->host; 1594 1595 if (pos + copied > inode->i_size) 1596 i_size_write(inode, pos + copied); 1597 1598 unlock_page(page); 1599 set_page_dirty(page); 1600 page_cache_release(page); 1601 1602 return copied; 1603} 1604 1605static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1606{ 1607 struct inode *inode = filp->f_path.dentry->d_inode; 1608 struct address_space *mapping = inode->i_mapping; 1609 unsigned long index, offset; 1610 enum sgp_type sgp = SGP_READ; 1611 1612 /* 1613 * Might this read be for a stacking filesystem? Then when reading 1614 * holes of a sparse file, we actually need to allocate those pages, 1615 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1616 */ 1617 if (segment_eq(get_fs(), KERNEL_DS)) 1618 sgp = SGP_DIRTY; 1619 1620 index = *ppos >> PAGE_CACHE_SHIFT; 1621 offset = *ppos & ~PAGE_CACHE_MASK; 1622 1623 for (;;) { 1624 struct page *page = NULL; 1625 unsigned long end_index, nr, ret; 1626 loff_t i_size = i_size_read(inode); 1627 1628 end_index = i_size >> PAGE_CACHE_SHIFT; 1629 if (index > end_index) 1630 break; 1631 if (index == end_index) { 1632 nr = i_size & ~PAGE_CACHE_MASK; 1633 if (nr <= offset) 1634 break; 1635 } 1636 1637 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1638 if (desc->error) { 1639 if (desc->error == -EINVAL) 1640 desc->error = 0; 1641 break; 1642 } 1643 if (page) 1644 unlock_page(page); 1645 1646 /* 1647 * We must evaluate after, since reads (unlike writes) 1648 * are called without i_mutex protection against truncate 1649 */ 1650 nr = PAGE_CACHE_SIZE; 1651 i_size = i_size_read(inode); 1652 end_index = i_size >> PAGE_CACHE_SHIFT; 1653 if (index == end_index) { 1654 nr = i_size & ~PAGE_CACHE_MASK; 1655 if (nr <= offset) { 1656 if (page) 1657 page_cache_release(page); 1658 break; 1659 } 1660 } 1661 nr -= offset; 1662 1663 if (page) { 1664 /* 1665 * If users can be writing to this page using arbitrary 1666 * virtual addresses, take care about potential aliasing 1667 * before reading the page on the kernel side. 1668 */ 1669 if (mapping_writably_mapped(mapping)) 1670 flush_dcache_page(page); 1671 /* 1672 * Mark the page accessed if we read the beginning. 1673 */ 1674 if (!offset) 1675 mark_page_accessed(page); 1676 } else { 1677 page = ZERO_PAGE(0); 1678 page_cache_get(page); 1679 } 1680 1681 /* 1682 * Ok, we have the page, and it's up-to-date, so 1683 * now we can copy it to user space... 1684 * 1685 * The actor routine returns how many bytes were actually used.. 1686 * NOTE! This may not be the same as how much of a user buffer 1687 * we filled up (we may be padding etc), so we can only update 1688 * "pos" here (the actor routine has to update the user buffer 1689 * pointers and the remaining count). 1690 */ 1691 ret = actor(desc, page, offset, nr); 1692 offset += ret; 1693 index += offset >> PAGE_CACHE_SHIFT; 1694 offset &= ~PAGE_CACHE_MASK; 1695 1696 page_cache_release(page); 1697 if (ret != nr || !desc->count) 1698 break; 1699 1700 cond_resched(); 1701 } 1702 1703 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1704 file_accessed(filp); 1705} 1706 1707static ssize_t shmem_file_aio_read(struct kiocb *iocb, 1708 const struct iovec *iov, unsigned long nr_segs, loff_t pos) 1709{ 1710 struct file *filp = iocb->ki_filp; 1711 ssize_t retval; 1712 unsigned long seg; 1713 size_t count; 1714 loff_t *ppos = &iocb->ki_pos; 1715 1716 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); 1717 if (retval) 1718 return retval; 1719 1720 for (seg = 0; seg < nr_segs; seg++) { 1721 read_descriptor_t desc; 1722 1723 desc.written = 0; 1724 desc.arg.buf = iov[seg].iov_base; 1725 desc.count = iov[seg].iov_len; 1726 if (desc.count == 0) 1727 continue; 1728 desc.error = 0; 1729 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1730 retval += desc.written; 1731 if (desc.error) { 1732 retval = retval ?: desc.error; 1733 break; 1734 } 1735 if (desc.count > 0) 1736 break; 1737 } 1738 return retval; 1739} 1740 1741static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1742{ 1743 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1744 1745 buf->f_type = TMPFS_MAGIC; 1746 buf->f_bsize = PAGE_CACHE_SIZE; 1747 buf->f_namelen = NAME_MAX; 1748 spin_lock(&sbinfo->stat_lock); 1749 if (sbinfo->max_blocks) { 1750 buf->f_blocks = sbinfo->max_blocks; 1751 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1752 } 1753 if (sbinfo->max_inodes) { 1754 buf->f_files = sbinfo->max_inodes; 1755 buf->f_ffree = sbinfo->free_inodes; 1756 } 1757 /* else leave those fields 0 like simple_statfs */ 1758 spin_unlock(&sbinfo->stat_lock); 1759 return 0; 1760} 1761 1762/* 1763 * File creation. Allocate an inode, and we're done.. 1764 */ 1765static int 1766shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1767{ 1768 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1769 int error = -ENOSPC; 1770 1771 if (inode) { 1772 error = security_inode_init_security(inode, dir, NULL, NULL, 1773 NULL); 1774 if (error) { 1775 if (error != -EOPNOTSUPP) { 1776 iput(inode); 1777 return error; 1778 } 1779 } 1780 error = shmem_acl_init(inode, dir); 1781 if (error) { 1782 iput(inode); 1783 return error; 1784 } 1785 if (dir->i_mode & S_ISGID) { 1786 inode->i_gid = dir->i_gid; 1787 if (S_ISDIR(mode)) 1788 inode->i_mode |= S_ISGID; 1789 } 1790 dir->i_size += BOGO_DIRENT_SIZE; 1791 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1792 d_instantiate(dentry, inode); 1793 dget(dentry); /* Extra count - pin the dentry in core */ 1794 } 1795 return error; 1796} 1797 1798static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1799{ 1800 int error; 1801 1802 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1803 return error; 1804 inc_nlink(dir); 1805 return 0; 1806} 1807 1808static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1809 struct nameidata *nd) 1810{ 1811 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1812} 1813 1814/* 1815 * Link a file.. 1816 */ 1817static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1818{ 1819 struct inode *inode = old_dentry->d_inode; 1820 int ret; 1821 1822 /* 1823 * No ordinary (disk based) filesystem counts links as inodes; 1824 * but each new link needs a new dentry, pinning lowmem, and 1825 * tmpfs dentries cannot be pruned until they are unlinked. 1826 */ 1827 ret = shmem_reserve_inode(inode->i_sb); 1828 if (ret) 1829 goto out; 1830 1831 dir->i_size += BOGO_DIRENT_SIZE; 1832 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1833 inc_nlink(inode); 1834 atomic_inc(&inode->i_count); /* New dentry reference */ 1835 dget(dentry); /* Extra pinning count for the created dentry */ 1836 d_instantiate(dentry, inode); 1837out: 1838 return ret; 1839} 1840 1841static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1842{ 1843 struct inode *inode = dentry->d_inode; 1844 1845 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1846 shmem_free_inode(inode->i_sb); 1847 1848 dir->i_size -= BOGO_DIRENT_SIZE; 1849 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1850 drop_nlink(inode); 1851 dput(dentry); /* Undo the count from "create" - this does all the work */ 1852 return 0; 1853} 1854 1855static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1856{ 1857 if (!simple_empty(dentry)) 1858 return -ENOTEMPTY; 1859 1860 drop_nlink(dentry->d_inode); 1861 drop_nlink(dir); 1862 return shmem_unlink(dir, dentry); 1863} 1864 1865/* 1866 * The VFS layer already does all the dentry stuff for rename, 1867 * we just have to decrement the usage count for the target if 1868 * it exists so that the VFS layer correctly free's it when it 1869 * gets overwritten. 1870 */ 1871static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1872{ 1873 struct inode *inode = old_dentry->d_inode; 1874 int they_are_dirs = S_ISDIR(inode->i_mode); 1875 1876 if (!simple_empty(new_dentry)) 1877 return -ENOTEMPTY; 1878 1879 if (new_dentry->d_inode) { 1880 (void) shmem_unlink(new_dir, new_dentry); 1881 if (they_are_dirs) 1882 drop_nlink(old_dir); 1883 } else if (they_are_dirs) { 1884 drop_nlink(old_dir); 1885 inc_nlink(new_dir); 1886 } 1887 1888 old_dir->i_size -= BOGO_DIRENT_SIZE; 1889 new_dir->i_size += BOGO_DIRENT_SIZE; 1890 old_dir->i_ctime = old_dir->i_mtime = 1891 new_dir->i_ctime = new_dir->i_mtime = 1892 inode->i_ctime = CURRENT_TIME; 1893 return 0; 1894} 1895 1896static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1897{ 1898 int error; 1899 int len; 1900 struct inode *inode; 1901 struct page *page = NULL; 1902 char *kaddr; 1903 struct shmem_inode_info *info; 1904 1905 len = strlen(symname) + 1; 1906 if (len > PAGE_CACHE_SIZE) 1907 return -ENAMETOOLONG; 1908 1909 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1910 if (!inode) 1911 return -ENOSPC; 1912 1913 error = security_inode_init_security(inode, dir, NULL, NULL, 1914 NULL); 1915 if (error) { 1916 if (error != -EOPNOTSUPP) { 1917 iput(inode); 1918 return error; 1919 } 1920 error = 0; 1921 } 1922 1923 info = SHMEM_I(inode); 1924 inode->i_size = len-1; 1925 if (len <= (char *)inode - (char *)info) { 1926 /* do it inline */ 1927 memcpy(info, symname, len); 1928 inode->i_op = &shmem_symlink_inline_operations; 1929 } else { 1930 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1931 if (error) { 1932 iput(inode); 1933 return error; 1934 } 1935 unlock_page(page); 1936 inode->i_mapping->a_ops = &shmem_aops; 1937 inode->i_op = &shmem_symlink_inode_operations; 1938 kaddr = kmap_atomic(page, KM_USER0); 1939 memcpy(kaddr, symname, len); 1940 kunmap_atomic(kaddr, KM_USER0); 1941 set_page_dirty(page); 1942 page_cache_release(page); 1943 } 1944 if (dir->i_mode & S_ISGID) 1945 inode->i_gid = dir->i_gid; 1946 dir->i_size += BOGO_DIRENT_SIZE; 1947 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1948 d_instantiate(dentry, inode); 1949 dget(dentry); 1950 return 0; 1951} 1952 1953static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1954{ 1955 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1956 return NULL; 1957} 1958 1959static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1960{ 1961 struct page *page = NULL; 1962 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1963 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1964 if (page) 1965 unlock_page(page); 1966 return page; 1967} 1968 1969static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1970{ 1971 if (!IS_ERR(nd_get_link(nd))) { 1972 struct page *page = cookie; 1973 kunmap(page); 1974 mark_page_accessed(page); 1975 page_cache_release(page); 1976 } 1977} 1978 1979static const struct inode_operations shmem_symlink_inline_operations = { 1980 .readlink = generic_readlink, 1981 .follow_link = shmem_follow_link_inline, 1982}; 1983 1984static const struct inode_operations shmem_symlink_inode_operations = { 1985 .truncate = shmem_truncate, 1986 .readlink = generic_readlink, 1987 .follow_link = shmem_follow_link, 1988 .put_link = shmem_put_link, 1989}; 1990 1991#ifdef CONFIG_TMPFS_POSIX_ACL 1992/* 1993 * Superblocks without xattr inode operations will get security.* xattr 1994 * support from the VFS "for free". As soon as we have any other xattrs 1995 * like ACLs, we also need to implement the security.* handlers at 1996 * filesystem level, though. 1997 */ 1998 1999static size_t shmem_xattr_security_list(struct inode *inode, char *list, 2000 size_t list_len, const char *name, 2001 size_t name_len) 2002{ 2003 return security_inode_listsecurity(inode, list, list_len); 2004} 2005 2006static int shmem_xattr_security_get(struct inode *inode, const char *name, 2007 void *buffer, size_t size) 2008{ 2009 if (strcmp(name, "") == 0) 2010 return -EINVAL; 2011 return xattr_getsecurity(inode, name, buffer, size); 2012} 2013 2014static int shmem_xattr_security_set(struct inode *inode, const char *name, 2015 const void *value, size_t size, int flags) 2016{ 2017 if (strcmp(name, "") == 0) 2018 return -EINVAL; 2019 return security_inode_setsecurity(inode, name, value, size, flags); 2020} 2021 2022static struct xattr_handler shmem_xattr_security_handler = { 2023 .prefix = XATTR_SECURITY_PREFIX, 2024 .list = shmem_xattr_security_list, 2025 .get = shmem_xattr_security_get, 2026 .set = shmem_xattr_security_set, 2027}; 2028 2029static struct xattr_handler *shmem_xattr_handlers[] = { 2030 &shmem_xattr_acl_access_handler, 2031 &shmem_xattr_acl_default_handler, 2032 &shmem_xattr_security_handler, 2033 NULL 2034}; 2035#endif 2036 2037static struct dentry *shmem_get_parent(struct dentry *child) 2038{ 2039 return ERR_PTR(-ESTALE); 2040} 2041 2042static int shmem_match(struct inode *ino, void *vfh) 2043{ 2044 __u32 *fh = vfh; 2045 __u64 inum = fh[2]; 2046 inum = (inum << 32) | fh[1]; 2047 return ino->i_ino == inum && fh[0] == ino->i_generation; 2048} 2049 2050static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2051 struct fid *fid, int fh_len, int fh_type) 2052{ 2053 struct inode *inode; 2054 struct dentry *dentry = NULL; 2055 u64 inum = fid->raw[2]; 2056 inum = (inum << 32) | fid->raw[1]; 2057 2058 if (fh_len < 3) 2059 return NULL; 2060 2061 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2062 shmem_match, fid->raw); 2063 if (inode) { 2064 dentry = d_find_alias(inode); 2065 iput(inode); 2066 } 2067 2068 return dentry; 2069} 2070 2071static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2072 int connectable) 2073{ 2074 struct inode *inode = dentry->d_inode; 2075 2076 if (*len < 3) 2077 return 255; 2078 2079 if (hlist_unhashed(&inode->i_hash)) { 2080 /* Unfortunately insert_inode_hash is not idempotent, 2081 * so as we hash inodes here rather than at creation 2082 * time, we need a lock to ensure we only try 2083 * to do it once 2084 */ 2085 static DEFINE_SPINLOCK(lock); 2086 spin_lock(&lock); 2087 if (hlist_unhashed(&inode->i_hash)) 2088 __insert_inode_hash(inode, 2089 inode->i_ino + inode->i_generation); 2090 spin_unlock(&lock); 2091 } 2092 2093 fh[0] = inode->i_generation; 2094 fh[1] = inode->i_ino; 2095 fh[2] = ((__u64)inode->i_ino) >> 32; 2096 2097 *len = 3; 2098 return 1; 2099} 2100 2101static const struct export_operations shmem_export_ops = { 2102 .get_parent = shmem_get_parent, 2103 .encode_fh = shmem_encode_fh, 2104 .fh_to_dentry = shmem_fh_to_dentry, 2105}; 2106 2107static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 2108 bool remount) 2109{ 2110 char *this_char, *value, *rest; 2111 2112 while (options != NULL) { 2113 this_char = options; 2114 for (;;) { 2115 /* 2116 * NUL-terminate this option: unfortunately, 2117 * mount options form a comma-separated list, 2118 * but mpol's nodelist may also contain commas. 2119 */ 2120 options = strchr(options, ','); 2121 if (options == NULL) 2122 break; 2123 options++; 2124 if (!isdigit(*options)) { 2125 options[-1] = '\0'; 2126 break; 2127 } 2128 } 2129 if (!*this_char) 2130 continue; 2131 if ((value = strchr(this_char,'=')) != NULL) { 2132 *value++ = 0; 2133 } else { 2134 printk(KERN_ERR 2135 "tmpfs: No value for mount option '%s'\n", 2136 this_char); 2137 return 1; 2138 } 2139 2140 if (!strcmp(this_char,"size")) { 2141 unsigned long long size; 2142 size = memparse(value,&rest); 2143 if (*rest == '%') { 2144 size <<= PAGE_SHIFT; 2145 size *= totalram_pages; 2146 do_div(size, 100); 2147 rest++; 2148 } 2149 if (*rest) 2150 goto bad_val; 2151 sbinfo->max_blocks = 2152 DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2153 } else if (!strcmp(this_char,"nr_blocks")) { 2154 sbinfo->max_blocks = memparse(value, &rest); 2155 if (*rest) 2156 goto bad_val; 2157 } else if (!strcmp(this_char,"nr_inodes")) { 2158 sbinfo->max_inodes = memparse(value, &rest); 2159 if (*rest) 2160 goto bad_val; 2161 } else if (!strcmp(this_char,"mode")) { 2162 if (remount) 2163 continue; 2164 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; 2165 if (*rest) 2166 goto bad_val; 2167 } else if (!strcmp(this_char,"uid")) { 2168 if (remount) 2169 continue; 2170 sbinfo->uid = simple_strtoul(value, &rest, 0); 2171 if (*rest) 2172 goto bad_val; 2173 } else if (!strcmp(this_char,"gid")) { 2174 if (remount) 2175 continue; 2176 sbinfo->gid = simple_strtoul(value, &rest, 0); 2177 if (*rest) 2178 goto bad_val; 2179 } else if (!strcmp(this_char,"mpol")) { 2180 if (mpol_parse_str(value, &sbinfo->mpol, 1)) 2181 goto bad_val; 2182 } else { 2183 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2184 this_char); 2185 return 1; 2186 } 2187 } 2188 return 0; 2189 2190bad_val: 2191 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2192 value, this_char); 2193 return 1; 2194 2195} 2196 2197static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2198{ 2199 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2200 struct shmem_sb_info config = *sbinfo; 2201 unsigned long blocks; 2202 unsigned long inodes; 2203 int error = -EINVAL; 2204 2205 if (shmem_parse_options(data, &config, true)) 2206 return error; 2207 2208 spin_lock(&sbinfo->stat_lock); 2209 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2210 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2211 if (config.max_blocks < blocks) 2212 goto out; 2213 if (config.max_inodes < inodes) 2214 goto out; 2215 /* 2216 * Those tests also disallow limited->unlimited while any are in 2217 * use, so i_blocks will always be zero when max_blocks is zero; 2218 * but we must separately disallow unlimited->limited, because 2219 * in that case we have no record of how much is already in use. 2220 */ 2221 if (config.max_blocks && !sbinfo->max_blocks) 2222 goto out; 2223 if (config.max_inodes && !sbinfo->max_inodes) 2224 goto out; 2225 2226 error = 0; 2227 sbinfo->max_blocks = config.max_blocks; 2228 sbinfo->free_blocks = config.max_blocks - blocks; 2229 sbinfo->max_inodes = config.max_inodes; 2230 sbinfo->free_inodes = config.max_inodes - inodes; 2231 2232 mpol_put(sbinfo->mpol); 2233 sbinfo->mpol = config.mpol; /* transfers initial ref */ 2234out: 2235 spin_unlock(&sbinfo->stat_lock); 2236 return error; 2237} 2238 2239static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) 2240{ 2241 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); 2242 2243 if (sbinfo->max_blocks != shmem_default_max_blocks()) 2244 seq_printf(seq, ",size=%luk", 2245 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); 2246 if (sbinfo->max_inodes != shmem_default_max_inodes()) 2247 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); 2248 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) 2249 seq_printf(seq, ",mode=%03o", sbinfo->mode); 2250 if (sbinfo->uid != 0) 2251 seq_printf(seq, ",uid=%u", sbinfo->uid); 2252 if (sbinfo->gid != 0) 2253 seq_printf(seq, ",gid=%u", sbinfo->gid); 2254 shmem_show_mpol(seq, sbinfo->mpol); 2255 return 0; 2256} 2257#endif /* CONFIG_TMPFS */ 2258 2259static void shmem_put_super(struct super_block *sb) 2260{ 2261 kfree(sb->s_fs_info); 2262 sb->s_fs_info = NULL; 2263} 2264 2265static int shmem_fill_super(struct super_block *sb, 2266 void *data, int silent) 2267{ 2268 struct inode *inode; 2269 struct dentry *root; 2270 struct shmem_sb_info *sbinfo; 2271 int err = -ENOMEM; 2272 2273 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2274 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2275 L1_CACHE_BYTES), GFP_KERNEL); 2276 if (!sbinfo) 2277 return -ENOMEM; 2278 2279 sbinfo->max_blocks = 0; 2280 sbinfo->max_inodes = 0; 2281 sbinfo->mode = S_IRWXUGO | S_ISVTX; 2282 sbinfo->uid = current_fsuid(); 2283 sbinfo->gid = current_fsgid(); 2284 sbinfo->mpol = NULL; 2285 sb->s_fs_info = sbinfo; 2286 2287#ifdef CONFIG_TMPFS 2288 /* 2289 * Per default we only allow half of the physical ram per 2290 * tmpfs instance, limiting inodes to one per page of lowmem; 2291 * but the internal instance is left unlimited. 2292 */ 2293 if (!(sb->s_flags & MS_NOUSER)) { 2294 sbinfo->max_blocks = shmem_default_max_blocks(); 2295 sbinfo->max_inodes = shmem_default_max_inodes(); 2296 if (shmem_parse_options(data, sbinfo, false)) { 2297 err = -EINVAL; 2298 goto failed; 2299 } 2300 } 2301 sb->s_export_op = &shmem_export_ops; 2302#else 2303 sb->s_flags |= MS_NOUSER; 2304#endif 2305 2306 spin_lock_init(&sbinfo->stat_lock); 2307 sbinfo->free_blocks = sbinfo->max_blocks; 2308 sbinfo->free_inodes = sbinfo->max_inodes; 2309 2310 sb->s_maxbytes = SHMEM_MAX_BYTES; 2311 sb->s_blocksize = PAGE_CACHE_SIZE; 2312 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2313 sb->s_magic = TMPFS_MAGIC; 2314 sb->s_op = &shmem_ops; 2315 sb->s_time_gran = 1; 2316#ifdef CONFIG_TMPFS_POSIX_ACL 2317 sb->s_xattr = shmem_xattr_handlers; 2318 sb->s_flags |= MS_POSIXACL; 2319#endif 2320 2321 inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0); 2322 if (!inode) 2323 goto failed; 2324 inode->i_uid = sbinfo->uid; 2325 inode->i_gid = sbinfo->gid; 2326 root = d_alloc_root(inode); 2327 if (!root) 2328 goto failed_iput; 2329 sb->s_root = root; 2330 return 0; 2331 2332failed_iput: 2333 iput(inode); 2334failed: 2335 shmem_put_super(sb); 2336 return err; 2337} 2338 2339static struct kmem_cache *shmem_inode_cachep; 2340 2341static struct inode *shmem_alloc_inode(struct super_block *sb) 2342{ 2343 struct shmem_inode_info *p; 2344 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2345 if (!p) 2346 return NULL; 2347 return &p->vfs_inode; 2348} 2349 2350static void shmem_destroy_inode(struct inode *inode) 2351{ 2352 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2353 /* only struct inode is valid if it's an inline symlink */ 2354 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2355 } 2356 shmem_acl_destroy_inode(inode); 2357 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2358} 2359 2360static void init_once(void *foo) 2361{ 2362 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2363 2364 inode_init_once(&p->vfs_inode); 2365#ifdef CONFIG_TMPFS_POSIX_ACL 2366 p->i_acl = NULL; 2367 p->i_default_acl = NULL; 2368#endif 2369} 2370 2371static int init_inodecache(void) 2372{ 2373 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2374 sizeof(struct shmem_inode_info), 2375 0, SLAB_PANIC, init_once); 2376 return 0; 2377} 2378 2379static void destroy_inodecache(void) 2380{ 2381 kmem_cache_destroy(shmem_inode_cachep); 2382} 2383 2384static const struct address_space_operations shmem_aops = { 2385 .writepage = shmem_writepage, 2386 .set_page_dirty = __set_page_dirty_no_writeback, 2387#ifdef CONFIG_TMPFS 2388 .readpage = shmem_readpage, 2389 .write_begin = shmem_write_begin, 2390 .write_end = shmem_write_end, 2391#endif 2392 .migratepage = migrate_page, 2393}; 2394 2395static const struct file_operations shmem_file_operations = { 2396 .mmap = shmem_mmap, 2397#ifdef CONFIG_TMPFS 2398 .llseek = generic_file_llseek, 2399 .read = do_sync_read, 2400 .write = do_sync_write, 2401 .aio_read = shmem_file_aio_read, 2402 .aio_write = generic_file_aio_write, 2403 .fsync = simple_sync_file, 2404 .splice_read = generic_file_splice_read, 2405 .splice_write = generic_file_splice_write, 2406#endif 2407}; 2408 2409static const struct inode_operations shmem_inode_operations = { 2410 .truncate = shmem_truncate, 2411 .setattr = shmem_notify_change, 2412 .truncate_range = shmem_truncate_range, 2413#ifdef CONFIG_TMPFS_POSIX_ACL 2414 .setxattr = generic_setxattr, 2415 .getxattr = generic_getxattr, 2416 .listxattr = generic_listxattr, 2417 .removexattr = generic_removexattr, 2418 .permission = shmem_permission, 2419#endif 2420 2421}; 2422 2423static const struct inode_operations shmem_dir_inode_operations = { 2424#ifdef CONFIG_TMPFS 2425 .create = shmem_create, 2426 .lookup = simple_lookup, 2427 .link = shmem_link, 2428 .unlink = shmem_unlink, 2429 .symlink = shmem_symlink, 2430 .mkdir = shmem_mkdir, 2431 .rmdir = shmem_rmdir, 2432 .mknod = shmem_mknod, 2433 .rename = shmem_rename, 2434#endif 2435#ifdef CONFIG_TMPFS_POSIX_ACL 2436 .setattr = shmem_notify_change, 2437 .setxattr = generic_setxattr, 2438 .getxattr = generic_getxattr, 2439 .listxattr = generic_listxattr, 2440 .removexattr = generic_removexattr, 2441 .permission = shmem_permission, 2442#endif 2443}; 2444 2445static const struct inode_operations shmem_special_inode_operations = { 2446#ifdef CONFIG_TMPFS_POSIX_ACL 2447 .setattr = shmem_notify_change, 2448 .setxattr = generic_setxattr, 2449 .getxattr = generic_getxattr, 2450 .listxattr = generic_listxattr, 2451 .removexattr = generic_removexattr, 2452 .permission = shmem_permission, 2453#endif 2454}; 2455 2456static const struct super_operations shmem_ops = { 2457 .alloc_inode = shmem_alloc_inode, 2458 .destroy_inode = shmem_destroy_inode, 2459#ifdef CONFIG_TMPFS 2460 .statfs = shmem_statfs, 2461 .remount_fs = shmem_remount_fs, 2462 .show_options = shmem_show_options, 2463#endif 2464 .delete_inode = shmem_delete_inode, 2465 .drop_inode = generic_delete_inode, 2466 .put_super = shmem_put_super, 2467}; 2468 2469static struct vm_operations_struct shmem_vm_ops = { 2470 .fault = shmem_fault, 2471#ifdef CONFIG_NUMA 2472 .set_policy = shmem_set_policy, 2473 .get_policy = shmem_get_policy, 2474#endif 2475}; 2476 2477 2478static int shmem_get_sb(struct file_system_type *fs_type, 2479 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2480{ 2481 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2482} 2483 2484static struct file_system_type tmpfs_fs_type = { 2485 .owner = THIS_MODULE, 2486 .name = "tmpfs", 2487 .get_sb = shmem_get_sb, 2488 .kill_sb = kill_litter_super, 2489}; 2490static struct vfsmount *shm_mnt; 2491 2492static int __init init_tmpfs(void) 2493{ 2494 int error; 2495 2496 error = bdi_init(&shmem_backing_dev_info); 2497 if (error) 2498 goto out4; 2499 2500 error = init_inodecache(); 2501 if (error) 2502 goto out3; 2503 2504 error = register_filesystem(&tmpfs_fs_type); 2505 if (error) { 2506 printk(KERN_ERR "Could not register tmpfs\n"); 2507 goto out2; 2508 } 2509 2510 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2511 tmpfs_fs_type.name, NULL); 2512 if (IS_ERR(shm_mnt)) { 2513 error = PTR_ERR(shm_mnt); 2514 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2515 goto out1; 2516 } 2517 return 0; 2518 2519out1: 2520 unregister_filesystem(&tmpfs_fs_type); 2521out2: 2522 destroy_inodecache(); 2523out3: 2524 bdi_destroy(&shmem_backing_dev_info); 2525out4: 2526 shm_mnt = ERR_PTR(error); 2527 return error; 2528} 2529module_init(init_tmpfs) 2530 2531/** 2532 * shmem_file_setup - get an unlinked file living in tmpfs 2533 * @name: name for dentry (to be seen in /proc/<pid>/maps 2534 * @size: size to be set for the file 2535 * @flags: vm_flags 2536 */ 2537struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2538{ 2539 int error; 2540 struct file *file; 2541 struct inode *inode; 2542 struct dentry *dentry, *root; 2543 struct qstr this; 2544 2545 if (IS_ERR(shm_mnt)) 2546 return (void *)shm_mnt; 2547 2548 if (size < 0 || size > SHMEM_MAX_BYTES) 2549 return ERR_PTR(-EINVAL); 2550 2551 if (shmem_acct_size(flags, size)) 2552 return ERR_PTR(-ENOMEM); 2553 2554 error = -ENOMEM; 2555 this.name = name; 2556 this.len = strlen(name); 2557 this.hash = 0; /* will go */ 2558 root = shm_mnt->mnt_root; 2559 dentry = d_alloc(root, &this); 2560 if (!dentry) 2561 goto put_memory; 2562 2563 error = -ENFILE; 2564 file = get_empty_filp(); 2565 if (!file) 2566 goto put_dentry; 2567 2568 error = -ENOSPC; 2569 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2570 if (!inode) 2571 goto close_file; 2572 2573 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2574 d_instantiate(dentry, inode); 2575 inode->i_size = size; 2576 inode->i_nlink = 0; /* It is unlinked */ 2577 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ, 2578 &shmem_file_operations); 2579 return file; 2580 2581close_file: 2582 put_filp(file); 2583put_dentry: 2584 dput(dentry); 2585put_memory: 2586 shmem_unacct_size(flags, size); 2587 return ERR_PTR(error); 2588} 2589EXPORT_SYMBOL_GPL(shmem_file_setup); 2590 2591/** 2592 * shmem_zero_setup - setup a shared anonymous mapping 2593 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2594 */ 2595int shmem_zero_setup(struct vm_area_struct *vma) 2596{ 2597 struct file *file; 2598 loff_t size = vma->vm_end - vma->vm_start; 2599 2600 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2601 if (IS_ERR(file)) 2602 return PTR_ERR(file); 2603 2604 ima_shm_check(file); 2605 if (vma->vm_file) 2606 fput(vma->vm_file); 2607 vma->vm_file = file; 2608 vma->vm_ops = &shmem_vm_ops; 2609 return 0; 2610} 2611