shmem.c revision 69029cd550284e32de13d6dd2f77b723c8a0e444
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 54#include <asm/uaccess.h> 55#include <asm/div64.h> 56#include <asm/pgtable.h> 57 58/* This magic number is used in glibc for posix shared memory */ 59#define TMPFS_MAGIC 0x01021994 60 61#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 62#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 63#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 64 65#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 66#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 67 68#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 69 70/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 71#define SHMEM_PAGEIN VM_READ 72#define SHMEM_TRUNCATE VM_WRITE 73 74/* Definition to limit shmem_truncate's steps between cond_rescheds */ 75#define LATENCY_LIMIT 64 76 77/* Pretend that each entry is of this size in directory's i_size */ 78#define BOGO_DIRENT_SIZE 20 79 80/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 81enum sgp_type { 82 SGP_READ, /* don't exceed i_size, don't allocate page */ 83 SGP_CACHE, /* don't exceed i_size, may allocate page */ 84 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ 85 SGP_WRITE, /* may exceed i_size, may allocate page */ 86}; 87 88#ifdef CONFIG_TMPFS 89static unsigned long shmem_default_max_blocks(void) 90{ 91 return totalram_pages / 2; 92} 93 94static unsigned long shmem_default_max_inodes(void) 95{ 96 return min(totalram_pages - totalhigh_pages, totalram_pages / 2); 97} 98#endif 99 100static int shmem_getpage(struct inode *inode, unsigned long idx, 101 struct page **pagep, enum sgp_type sgp, int *type); 102 103static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 104{ 105 /* 106 * The above definition of ENTRIES_PER_PAGE, and the use of 107 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 108 * might be reconsidered if it ever diverges from PAGE_SIZE. 109 * 110 * Mobility flags are masked out as swap vectors cannot move 111 */ 112 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, 113 PAGE_CACHE_SHIFT-PAGE_SHIFT); 114} 115 116static inline void shmem_dir_free(struct page *page) 117{ 118 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 119} 120 121static struct page **shmem_dir_map(struct page *page) 122{ 123 return (struct page **)kmap_atomic(page, KM_USER0); 124} 125 126static inline void shmem_dir_unmap(struct page **dir) 127{ 128 kunmap_atomic(dir, KM_USER0); 129} 130 131static swp_entry_t *shmem_swp_map(struct page *page) 132{ 133 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 134} 135 136static inline void shmem_swp_balance_unmap(void) 137{ 138 /* 139 * When passing a pointer to an i_direct entry, to code which 140 * also handles indirect entries and so will shmem_swp_unmap, 141 * we must arrange for the preempt count to remain in balance. 142 * What kmap_atomic of a lowmem page does depends on config 143 * and architecture, so pretend to kmap_atomic some lowmem page. 144 */ 145 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 146} 147 148static inline void shmem_swp_unmap(swp_entry_t *entry) 149{ 150 kunmap_atomic(entry, KM_USER1); 151} 152 153static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 154{ 155 return sb->s_fs_info; 156} 157 158/* 159 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 160 * for shared memory and for shared anonymous (/dev/zero) mappings 161 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 162 * consistent with the pre-accounting of private mappings ... 163 */ 164static inline int shmem_acct_size(unsigned long flags, loff_t size) 165{ 166 return (flags & VM_ACCOUNT)? 167 security_vm_enough_memory(VM_ACCT(size)): 0; 168} 169 170static inline void shmem_unacct_size(unsigned long flags, loff_t size) 171{ 172 if (flags & VM_ACCOUNT) 173 vm_unacct_memory(VM_ACCT(size)); 174} 175 176/* 177 * ... whereas tmpfs objects are accounted incrementally as 178 * pages are allocated, in order to allow huge sparse files. 179 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 180 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 181 */ 182static inline int shmem_acct_block(unsigned long flags) 183{ 184 return (flags & VM_ACCOUNT)? 185 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 186} 187 188static inline void shmem_unacct_blocks(unsigned long flags, long pages) 189{ 190 if (!(flags & VM_ACCOUNT)) 191 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 192} 193 194static const struct super_operations shmem_ops; 195static const struct address_space_operations shmem_aops; 196static const struct file_operations shmem_file_operations; 197static const struct inode_operations shmem_inode_operations; 198static const struct inode_operations shmem_dir_inode_operations; 199static const struct inode_operations shmem_special_inode_operations; 200static struct vm_operations_struct shmem_vm_ops; 201 202static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 203 .ra_pages = 0, /* No readahead */ 204 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, 205 .unplug_io_fn = default_unplug_io_fn, 206}; 207 208static LIST_HEAD(shmem_swaplist); 209static DEFINE_MUTEX(shmem_swaplist_mutex); 210 211static void shmem_free_blocks(struct inode *inode, long pages) 212{ 213 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 214 if (sbinfo->max_blocks) { 215 spin_lock(&sbinfo->stat_lock); 216 sbinfo->free_blocks += pages; 217 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 218 spin_unlock(&sbinfo->stat_lock); 219 } 220} 221 222static int shmem_reserve_inode(struct super_block *sb) 223{ 224 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 225 if (sbinfo->max_inodes) { 226 spin_lock(&sbinfo->stat_lock); 227 if (!sbinfo->free_inodes) { 228 spin_unlock(&sbinfo->stat_lock); 229 return -ENOSPC; 230 } 231 sbinfo->free_inodes--; 232 spin_unlock(&sbinfo->stat_lock); 233 } 234 return 0; 235} 236 237static void shmem_free_inode(struct super_block *sb) 238{ 239 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 240 if (sbinfo->max_inodes) { 241 spin_lock(&sbinfo->stat_lock); 242 sbinfo->free_inodes++; 243 spin_unlock(&sbinfo->stat_lock); 244 } 245} 246 247/** 248 * shmem_recalc_inode - recalculate the size of an inode 249 * @inode: inode to recalc 250 * 251 * We have to calculate the free blocks since the mm can drop 252 * undirtied hole pages behind our back. 253 * 254 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 255 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 256 * 257 * It has to be called with the spinlock held. 258 */ 259static void shmem_recalc_inode(struct inode *inode) 260{ 261 struct shmem_inode_info *info = SHMEM_I(inode); 262 long freed; 263 264 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 265 if (freed > 0) { 266 info->alloced -= freed; 267 shmem_unacct_blocks(info->flags, freed); 268 shmem_free_blocks(inode, freed); 269 } 270} 271 272/** 273 * shmem_swp_entry - find the swap vector position in the info structure 274 * @info: info structure for the inode 275 * @index: index of the page to find 276 * @page: optional page to add to the structure. Has to be preset to 277 * all zeros 278 * 279 * If there is no space allocated yet it will return NULL when 280 * page is NULL, else it will use the page for the needed block, 281 * setting it to NULL on return to indicate that it has been used. 282 * 283 * The swap vector is organized the following way: 284 * 285 * There are SHMEM_NR_DIRECT entries directly stored in the 286 * shmem_inode_info structure. So small files do not need an addional 287 * allocation. 288 * 289 * For pages with index > SHMEM_NR_DIRECT there is the pointer 290 * i_indirect which points to a page which holds in the first half 291 * doubly indirect blocks, in the second half triple indirect blocks: 292 * 293 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 294 * following layout (for SHMEM_NR_DIRECT == 16): 295 * 296 * i_indirect -> dir --> 16-19 297 * | +-> 20-23 298 * | 299 * +-->dir2 --> 24-27 300 * | +-> 28-31 301 * | +-> 32-35 302 * | +-> 36-39 303 * | 304 * +-->dir3 --> 40-43 305 * +-> 44-47 306 * +-> 48-51 307 * +-> 52-55 308 */ 309static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 310{ 311 unsigned long offset; 312 struct page **dir; 313 struct page *subdir; 314 315 if (index < SHMEM_NR_DIRECT) { 316 shmem_swp_balance_unmap(); 317 return info->i_direct+index; 318 } 319 if (!info->i_indirect) { 320 if (page) { 321 info->i_indirect = *page; 322 *page = NULL; 323 } 324 return NULL; /* need another page */ 325 } 326 327 index -= SHMEM_NR_DIRECT; 328 offset = index % ENTRIES_PER_PAGE; 329 index /= ENTRIES_PER_PAGE; 330 dir = shmem_dir_map(info->i_indirect); 331 332 if (index >= ENTRIES_PER_PAGE/2) { 333 index -= ENTRIES_PER_PAGE/2; 334 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 335 index %= ENTRIES_PER_PAGE; 336 subdir = *dir; 337 if (!subdir) { 338 if (page) { 339 *dir = *page; 340 *page = NULL; 341 } 342 shmem_dir_unmap(dir); 343 return NULL; /* need another page */ 344 } 345 shmem_dir_unmap(dir); 346 dir = shmem_dir_map(subdir); 347 } 348 349 dir += index; 350 subdir = *dir; 351 if (!subdir) { 352 if (!page || !(subdir = *page)) { 353 shmem_dir_unmap(dir); 354 return NULL; /* need a page */ 355 } 356 *dir = subdir; 357 *page = NULL; 358 } 359 shmem_dir_unmap(dir); 360 return shmem_swp_map(subdir) + offset; 361} 362 363static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 364{ 365 long incdec = value? 1: -1; 366 367 entry->val = value; 368 info->swapped += incdec; 369 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 370 struct page *page = kmap_atomic_to_page(entry); 371 set_page_private(page, page_private(page) + incdec); 372 } 373} 374 375/** 376 * shmem_swp_alloc - get the position of the swap entry for the page. 377 * @info: info structure for the inode 378 * @index: index of the page to find 379 * @sgp: check and recheck i_size? skip allocation? 380 * 381 * If the entry does not exist, allocate it. 382 */ 383static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 384{ 385 struct inode *inode = &info->vfs_inode; 386 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 387 struct page *page = NULL; 388 swp_entry_t *entry; 389 390 if (sgp != SGP_WRITE && 391 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 392 return ERR_PTR(-EINVAL); 393 394 while (!(entry = shmem_swp_entry(info, index, &page))) { 395 if (sgp == SGP_READ) 396 return shmem_swp_map(ZERO_PAGE(0)); 397 /* 398 * Test free_blocks against 1 not 0, since we have 1 data 399 * page (and perhaps indirect index pages) yet to allocate: 400 * a waste to allocate index if we cannot allocate data. 401 */ 402 if (sbinfo->max_blocks) { 403 spin_lock(&sbinfo->stat_lock); 404 if (sbinfo->free_blocks <= 1) { 405 spin_unlock(&sbinfo->stat_lock); 406 return ERR_PTR(-ENOSPC); 407 } 408 sbinfo->free_blocks--; 409 inode->i_blocks += BLOCKS_PER_PAGE; 410 spin_unlock(&sbinfo->stat_lock); 411 } 412 413 spin_unlock(&info->lock); 414 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); 415 if (page) 416 set_page_private(page, 0); 417 spin_lock(&info->lock); 418 419 if (!page) { 420 shmem_free_blocks(inode, 1); 421 return ERR_PTR(-ENOMEM); 422 } 423 if (sgp != SGP_WRITE && 424 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 425 entry = ERR_PTR(-EINVAL); 426 break; 427 } 428 if (info->next_index <= index) 429 info->next_index = index + 1; 430 } 431 if (page) { 432 /* another task gave its page, or truncated the file */ 433 shmem_free_blocks(inode, 1); 434 shmem_dir_free(page); 435 } 436 if (info->next_index <= index && !IS_ERR(entry)) 437 info->next_index = index + 1; 438 return entry; 439} 440 441/** 442 * shmem_free_swp - free some swap entries in a directory 443 * @dir: pointer to the directory 444 * @edir: pointer after last entry of the directory 445 * @punch_lock: pointer to spinlock when needed for the holepunch case 446 */ 447static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, 448 spinlock_t *punch_lock) 449{ 450 spinlock_t *punch_unlock = NULL; 451 swp_entry_t *ptr; 452 int freed = 0; 453 454 for (ptr = dir; ptr < edir; ptr++) { 455 if (ptr->val) { 456 if (unlikely(punch_lock)) { 457 punch_unlock = punch_lock; 458 punch_lock = NULL; 459 spin_lock(punch_unlock); 460 if (!ptr->val) 461 continue; 462 } 463 free_swap_and_cache(*ptr); 464 *ptr = (swp_entry_t){0}; 465 freed++; 466 } 467 } 468 if (punch_unlock) 469 spin_unlock(punch_unlock); 470 return freed; 471} 472 473static int shmem_map_and_free_swp(struct page *subdir, int offset, 474 int limit, struct page ***dir, spinlock_t *punch_lock) 475{ 476 swp_entry_t *ptr; 477 int freed = 0; 478 479 ptr = shmem_swp_map(subdir); 480 for (; offset < limit; offset += LATENCY_LIMIT) { 481 int size = limit - offset; 482 if (size > LATENCY_LIMIT) 483 size = LATENCY_LIMIT; 484 freed += shmem_free_swp(ptr+offset, ptr+offset+size, 485 punch_lock); 486 if (need_resched()) { 487 shmem_swp_unmap(ptr); 488 if (*dir) { 489 shmem_dir_unmap(*dir); 490 *dir = NULL; 491 } 492 cond_resched(); 493 ptr = shmem_swp_map(subdir); 494 } 495 } 496 shmem_swp_unmap(ptr); 497 return freed; 498} 499 500static void shmem_free_pages(struct list_head *next) 501{ 502 struct page *page; 503 int freed = 0; 504 505 do { 506 page = container_of(next, struct page, lru); 507 next = next->next; 508 shmem_dir_free(page); 509 freed++; 510 if (freed >= LATENCY_LIMIT) { 511 cond_resched(); 512 freed = 0; 513 } 514 } while (next); 515} 516 517static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 518{ 519 struct shmem_inode_info *info = SHMEM_I(inode); 520 unsigned long idx; 521 unsigned long size; 522 unsigned long limit; 523 unsigned long stage; 524 unsigned long diroff; 525 struct page **dir; 526 struct page *topdir; 527 struct page *middir; 528 struct page *subdir; 529 swp_entry_t *ptr; 530 LIST_HEAD(pages_to_free); 531 long nr_pages_to_free = 0; 532 long nr_swaps_freed = 0; 533 int offset; 534 int freed; 535 int punch_hole; 536 spinlock_t *needs_lock; 537 spinlock_t *punch_lock; 538 unsigned long upper_limit; 539 540 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 541 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 542 if (idx >= info->next_index) 543 return; 544 545 spin_lock(&info->lock); 546 info->flags |= SHMEM_TRUNCATE; 547 if (likely(end == (loff_t) -1)) { 548 limit = info->next_index; 549 upper_limit = SHMEM_MAX_INDEX; 550 info->next_index = idx; 551 needs_lock = NULL; 552 punch_hole = 0; 553 } else { 554 if (end + 1 >= inode->i_size) { /* we may free a little more */ 555 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> 556 PAGE_CACHE_SHIFT; 557 upper_limit = SHMEM_MAX_INDEX; 558 } else { 559 limit = (end + 1) >> PAGE_CACHE_SHIFT; 560 upper_limit = limit; 561 } 562 needs_lock = &info->lock; 563 punch_hole = 1; 564 } 565 566 topdir = info->i_indirect; 567 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 568 info->i_indirect = NULL; 569 nr_pages_to_free++; 570 list_add(&topdir->lru, &pages_to_free); 571 } 572 spin_unlock(&info->lock); 573 574 if (info->swapped && idx < SHMEM_NR_DIRECT) { 575 ptr = info->i_direct; 576 size = limit; 577 if (size > SHMEM_NR_DIRECT) 578 size = SHMEM_NR_DIRECT; 579 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); 580 } 581 582 /* 583 * If there are no indirect blocks or we are punching a hole 584 * below indirect blocks, nothing to be done. 585 */ 586 if (!topdir || limit <= SHMEM_NR_DIRECT) 587 goto done2; 588 589 /* 590 * The truncation case has already dropped info->lock, and we're safe 591 * because i_size and next_index have already been lowered, preventing 592 * access beyond. But in the punch_hole case, we still need to take 593 * the lock when updating the swap directory, because there might be 594 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or 595 * shmem_writepage. However, whenever we find we can remove a whole 596 * directory page (not at the misaligned start or end of the range), 597 * we first NULLify its pointer in the level above, and then have no 598 * need to take the lock when updating its contents: needs_lock and 599 * punch_lock (either pointing to info->lock or NULL) manage this. 600 */ 601 602 upper_limit -= SHMEM_NR_DIRECT; 603 limit -= SHMEM_NR_DIRECT; 604 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 605 offset = idx % ENTRIES_PER_PAGE; 606 idx -= offset; 607 608 dir = shmem_dir_map(topdir); 609 stage = ENTRIES_PER_PAGEPAGE/2; 610 if (idx < ENTRIES_PER_PAGEPAGE/2) { 611 middir = topdir; 612 diroff = idx/ENTRIES_PER_PAGE; 613 } else { 614 dir += ENTRIES_PER_PAGE/2; 615 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 616 while (stage <= idx) 617 stage += ENTRIES_PER_PAGEPAGE; 618 middir = *dir; 619 if (*dir) { 620 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 621 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 622 if (!diroff && !offset && upper_limit >= stage) { 623 if (needs_lock) { 624 spin_lock(needs_lock); 625 *dir = NULL; 626 spin_unlock(needs_lock); 627 needs_lock = NULL; 628 } else 629 *dir = NULL; 630 nr_pages_to_free++; 631 list_add(&middir->lru, &pages_to_free); 632 } 633 shmem_dir_unmap(dir); 634 dir = shmem_dir_map(middir); 635 } else { 636 diroff = 0; 637 offset = 0; 638 idx = stage; 639 } 640 } 641 642 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 643 if (unlikely(idx == stage)) { 644 shmem_dir_unmap(dir); 645 dir = shmem_dir_map(topdir) + 646 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 647 while (!*dir) { 648 dir++; 649 idx += ENTRIES_PER_PAGEPAGE; 650 if (idx >= limit) 651 goto done1; 652 } 653 stage = idx + ENTRIES_PER_PAGEPAGE; 654 middir = *dir; 655 if (punch_hole) 656 needs_lock = &info->lock; 657 if (upper_limit >= stage) { 658 if (needs_lock) { 659 spin_lock(needs_lock); 660 *dir = NULL; 661 spin_unlock(needs_lock); 662 needs_lock = NULL; 663 } else 664 *dir = NULL; 665 nr_pages_to_free++; 666 list_add(&middir->lru, &pages_to_free); 667 } 668 shmem_dir_unmap(dir); 669 cond_resched(); 670 dir = shmem_dir_map(middir); 671 diroff = 0; 672 } 673 punch_lock = needs_lock; 674 subdir = dir[diroff]; 675 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { 676 if (needs_lock) { 677 spin_lock(needs_lock); 678 dir[diroff] = NULL; 679 spin_unlock(needs_lock); 680 punch_lock = NULL; 681 } else 682 dir[diroff] = NULL; 683 nr_pages_to_free++; 684 list_add(&subdir->lru, &pages_to_free); 685 } 686 if (subdir && page_private(subdir) /* has swap entries */) { 687 size = limit - idx; 688 if (size > ENTRIES_PER_PAGE) 689 size = ENTRIES_PER_PAGE; 690 freed = shmem_map_and_free_swp(subdir, 691 offset, size, &dir, punch_lock); 692 if (!dir) 693 dir = shmem_dir_map(middir); 694 nr_swaps_freed += freed; 695 if (offset || punch_lock) { 696 spin_lock(&info->lock); 697 set_page_private(subdir, 698 page_private(subdir) - freed); 699 spin_unlock(&info->lock); 700 } else 701 BUG_ON(page_private(subdir) != freed); 702 } 703 offset = 0; 704 } 705done1: 706 shmem_dir_unmap(dir); 707done2: 708 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 709 /* 710 * Call truncate_inode_pages again: racing shmem_unuse_inode 711 * may have swizzled a page in from swap since vmtruncate or 712 * generic_delete_inode did it, before we lowered next_index. 713 * Also, though shmem_getpage checks i_size before adding to 714 * cache, no recheck after: so fix the narrow window there too. 715 * 716 * Recalling truncate_inode_pages_range and unmap_mapping_range 717 * every time for punch_hole (which never got a chance to clear 718 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 719 * yet hardly ever necessary: try to optimize them out later. 720 */ 721 truncate_inode_pages_range(inode->i_mapping, start, end); 722 if (punch_hole) 723 unmap_mapping_range(inode->i_mapping, start, 724 end - start, 1); 725 } 726 727 spin_lock(&info->lock); 728 info->flags &= ~SHMEM_TRUNCATE; 729 info->swapped -= nr_swaps_freed; 730 if (nr_pages_to_free) 731 shmem_free_blocks(inode, nr_pages_to_free); 732 shmem_recalc_inode(inode); 733 spin_unlock(&info->lock); 734 735 /* 736 * Empty swap vector directory pages to be freed? 737 */ 738 if (!list_empty(&pages_to_free)) { 739 pages_to_free.prev->next = NULL; 740 shmem_free_pages(pages_to_free.next); 741 } 742} 743 744static void shmem_truncate(struct inode *inode) 745{ 746 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 747} 748 749static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 750{ 751 struct inode *inode = dentry->d_inode; 752 struct page *page = NULL; 753 int error; 754 755 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 756 if (attr->ia_size < inode->i_size) { 757 /* 758 * If truncating down to a partial page, then 759 * if that page is already allocated, hold it 760 * in memory until the truncation is over, so 761 * truncate_partial_page cannnot miss it were 762 * it assigned to swap. 763 */ 764 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 765 (void) shmem_getpage(inode, 766 attr->ia_size>>PAGE_CACHE_SHIFT, 767 &page, SGP_READ, NULL); 768 if (page) 769 unlock_page(page); 770 } 771 /* 772 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 773 * detect if any pages might have been added to cache 774 * after truncate_inode_pages. But we needn't bother 775 * if it's being fully truncated to zero-length: the 776 * nrpages check is efficient enough in that case. 777 */ 778 if (attr->ia_size) { 779 struct shmem_inode_info *info = SHMEM_I(inode); 780 spin_lock(&info->lock); 781 info->flags &= ~SHMEM_PAGEIN; 782 spin_unlock(&info->lock); 783 } 784 } 785 } 786 787 error = inode_change_ok(inode, attr); 788 if (!error) 789 error = inode_setattr(inode, attr); 790#ifdef CONFIG_TMPFS_POSIX_ACL 791 if (!error && (attr->ia_valid & ATTR_MODE)) 792 error = generic_acl_chmod(inode, &shmem_acl_ops); 793#endif 794 if (page) 795 page_cache_release(page); 796 return error; 797} 798 799static void shmem_delete_inode(struct inode *inode) 800{ 801 struct shmem_inode_info *info = SHMEM_I(inode); 802 803 if (inode->i_op->truncate == shmem_truncate) { 804 truncate_inode_pages(inode->i_mapping, 0); 805 shmem_unacct_size(info->flags, inode->i_size); 806 inode->i_size = 0; 807 shmem_truncate(inode); 808 if (!list_empty(&info->swaplist)) { 809 mutex_lock(&shmem_swaplist_mutex); 810 list_del_init(&info->swaplist); 811 mutex_unlock(&shmem_swaplist_mutex); 812 } 813 } 814 BUG_ON(inode->i_blocks); 815 shmem_free_inode(inode->i_sb); 816 clear_inode(inode); 817} 818 819static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 820{ 821 swp_entry_t *ptr; 822 823 for (ptr = dir; ptr < edir; ptr++) { 824 if (ptr->val == entry.val) 825 return ptr - dir; 826 } 827 return -1; 828} 829 830static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 831{ 832 struct inode *inode; 833 unsigned long idx; 834 unsigned long size; 835 unsigned long limit; 836 unsigned long stage; 837 struct page **dir; 838 struct page *subdir; 839 swp_entry_t *ptr; 840 int offset; 841 int error; 842 843 idx = 0; 844 ptr = info->i_direct; 845 spin_lock(&info->lock); 846 if (!info->swapped) { 847 list_del_init(&info->swaplist); 848 goto lost2; 849 } 850 limit = info->next_index; 851 size = limit; 852 if (size > SHMEM_NR_DIRECT) 853 size = SHMEM_NR_DIRECT; 854 offset = shmem_find_swp(entry, ptr, ptr+size); 855 if (offset >= 0) 856 goto found; 857 if (!info->i_indirect) 858 goto lost2; 859 860 dir = shmem_dir_map(info->i_indirect); 861 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 862 863 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 864 if (unlikely(idx == stage)) { 865 shmem_dir_unmap(dir-1); 866 if (cond_resched_lock(&info->lock)) { 867 /* check it has not been truncated */ 868 if (limit > info->next_index) { 869 limit = info->next_index; 870 if (idx >= limit) 871 goto lost2; 872 } 873 } 874 dir = shmem_dir_map(info->i_indirect) + 875 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 876 while (!*dir) { 877 dir++; 878 idx += ENTRIES_PER_PAGEPAGE; 879 if (idx >= limit) 880 goto lost1; 881 } 882 stage = idx + ENTRIES_PER_PAGEPAGE; 883 subdir = *dir; 884 shmem_dir_unmap(dir); 885 dir = shmem_dir_map(subdir); 886 } 887 subdir = *dir; 888 if (subdir && page_private(subdir)) { 889 ptr = shmem_swp_map(subdir); 890 size = limit - idx; 891 if (size > ENTRIES_PER_PAGE) 892 size = ENTRIES_PER_PAGE; 893 offset = shmem_find_swp(entry, ptr, ptr+size); 894 shmem_swp_unmap(ptr); 895 if (offset >= 0) { 896 shmem_dir_unmap(dir); 897 goto found; 898 } 899 } 900 } 901lost1: 902 shmem_dir_unmap(dir-1); 903lost2: 904 spin_unlock(&info->lock); 905 return 0; 906found: 907 idx += offset; 908 inode = igrab(&info->vfs_inode); 909 spin_unlock(&info->lock); 910 911 /* 912 * Move _head_ to start search for next from here. 913 * But be careful: shmem_delete_inode checks list_empty without taking 914 * mutex, and there's an instant in list_move_tail when info->swaplist 915 * would appear empty, if it were the only one on shmem_swaplist. We 916 * could avoid doing it if inode NULL; or use this minor optimization. 917 */ 918 if (shmem_swaplist.next != &info->swaplist) 919 list_move_tail(&shmem_swaplist, &info->swaplist); 920 mutex_unlock(&shmem_swaplist_mutex); 921 922 error = 1; 923 if (!inode) 924 goto out; 925 /* Precharge page using GFP_KERNEL while we can wait */ 926 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); 927 if (error) 928 goto out; 929 error = radix_tree_preload(GFP_KERNEL); 930 if (error) { 931 mem_cgroup_uncharge_cache_page(page); 932 goto out; 933 } 934 error = 1; 935 936 spin_lock(&info->lock); 937 ptr = shmem_swp_entry(info, idx, NULL); 938 if (ptr && ptr->val == entry.val) { 939 error = add_to_page_cache(page, inode->i_mapping, 940 idx, GFP_NOWAIT); 941 /* does mem_cgroup_uncharge_cache_page on error */ 942 } else /* we must compensate for our precharge above */ 943 mem_cgroup_uncharge_cache_page(page); 944 945 if (error == -EEXIST) { 946 struct page *filepage = find_get_page(inode->i_mapping, idx); 947 error = 1; 948 if (filepage) { 949 /* 950 * There might be a more uptodate page coming down 951 * from a stacked writepage: forget our swappage if so. 952 */ 953 if (PageUptodate(filepage)) 954 error = 0; 955 page_cache_release(filepage); 956 } 957 } 958 if (!error) { 959 delete_from_swap_cache(page); 960 set_page_dirty(page); 961 info->flags |= SHMEM_PAGEIN; 962 shmem_swp_set(info, ptr, 0); 963 swap_free(entry); 964 error = 1; /* not an error, but entry was found */ 965 } 966 if (ptr) 967 shmem_swp_unmap(ptr); 968 spin_unlock(&info->lock); 969 radix_tree_preload_end(); 970out: 971 unlock_page(page); 972 page_cache_release(page); 973 iput(inode); /* allows for NULL */ 974 return error; 975} 976 977/* 978 * shmem_unuse() search for an eventually swapped out shmem page. 979 */ 980int shmem_unuse(swp_entry_t entry, struct page *page) 981{ 982 struct list_head *p, *next; 983 struct shmem_inode_info *info; 984 int found = 0; 985 986 mutex_lock(&shmem_swaplist_mutex); 987 list_for_each_safe(p, next, &shmem_swaplist) { 988 info = list_entry(p, struct shmem_inode_info, swaplist); 989 found = shmem_unuse_inode(info, entry, page); 990 cond_resched(); 991 if (found) 992 goto out; 993 } 994 mutex_unlock(&shmem_swaplist_mutex); 995out: return found; /* 0 or 1 or -ENOMEM */ 996} 997 998/* 999 * Move the page from the page cache to the swap cache. 1000 */ 1001static int shmem_writepage(struct page *page, struct writeback_control *wbc) 1002{ 1003 struct shmem_inode_info *info; 1004 swp_entry_t *entry, swap; 1005 struct address_space *mapping; 1006 unsigned long index; 1007 struct inode *inode; 1008 1009 BUG_ON(!PageLocked(page)); 1010 mapping = page->mapping; 1011 index = page->index; 1012 inode = mapping->host; 1013 info = SHMEM_I(inode); 1014 if (info->flags & VM_LOCKED) 1015 goto redirty; 1016 if (!total_swap_pages) 1017 goto redirty; 1018 1019 /* 1020 * shmem_backing_dev_info's capabilities prevent regular writeback or 1021 * sync from ever calling shmem_writepage; but a stacking filesystem 1022 * may use the ->writepage of its underlying filesystem, in which case 1023 * tmpfs should write out to swap only in response to memory pressure, 1024 * and not for pdflush or sync. However, in those cases, we do still 1025 * want to check if there's a redundant swappage to be discarded. 1026 */ 1027 if (wbc->for_reclaim) 1028 swap = get_swap_page(); 1029 else 1030 swap.val = 0; 1031 1032 spin_lock(&info->lock); 1033 if (index >= info->next_index) { 1034 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1035 goto unlock; 1036 } 1037 entry = shmem_swp_entry(info, index, NULL); 1038 if (entry->val) { 1039 /* 1040 * The more uptodate page coming down from a stacked 1041 * writepage should replace our old swappage. 1042 */ 1043 free_swap_and_cache(*entry); 1044 shmem_swp_set(info, entry, 0); 1045 } 1046 shmem_recalc_inode(inode); 1047 1048 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1049 remove_from_page_cache(page); 1050 shmem_swp_set(info, entry, swap.val); 1051 shmem_swp_unmap(entry); 1052 if (list_empty(&info->swaplist)) 1053 inode = igrab(inode); 1054 else 1055 inode = NULL; 1056 spin_unlock(&info->lock); 1057 swap_duplicate(swap); 1058 BUG_ON(page_mapped(page)); 1059 page_cache_release(page); /* pagecache ref */ 1060 set_page_dirty(page); 1061 unlock_page(page); 1062 if (inode) { 1063 mutex_lock(&shmem_swaplist_mutex); 1064 /* move instead of add in case we're racing */ 1065 list_move_tail(&info->swaplist, &shmem_swaplist); 1066 mutex_unlock(&shmem_swaplist_mutex); 1067 iput(inode); 1068 } 1069 return 0; 1070 } 1071 1072 shmem_swp_unmap(entry); 1073unlock: 1074 spin_unlock(&info->lock); 1075 swap_free(swap); 1076redirty: 1077 set_page_dirty(page); 1078 if (wbc->for_reclaim) 1079 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1080 unlock_page(page); 1081 return 0; 1082} 1083 1084#ifdef CONFIG_NUMA 1085#ifdef CONFIG_TMPFS 1086static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) 1087{ 1088 char buffer[64]; 1089 1090 if (!mpol || mpol->mode == MPOL_DEFAULT) 1091 return; /* show nothing */ 1092 1093 mpol_to_str(buffer, sizeof(buffer), mpol, 1); 1094 1095 seq_printf(seq, ",mpol=%s", buffer); 1096} 1097 1098static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1099{ 1100 struct mempolicy *mpol = NULL; 1101 if (sbinfo->mpol) { 1102 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ 1103 mpol = sbinfo->mpol; 1104 mpol_get(mpol); 1105 spin_unlock(&sbinfo->stat_lock); 1106 } 1107 return mpol; 1108} 1109#endif /* CONFIG_TMPFS */ 1110 1111static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1112 struct shmem_inode_info *info, unsigned long idx) 1113{ 1114 struct mempolicy mpol, *spol; 1115 struct vm_area_struct pvma; 1116 struct page *page; 1117 1118 spol = mpol_cond_copy(&mpol, 1119 mpol_shared_policy_lookup(&info->policy, idx)); 1120 1121 /* Create a pseudo vma that just contains the policy */ 1122 pvma.vm_start = 0; 1123 pvma.vm_pgoff = idx; 1124 pvma.vm_ops = NULL; 1125 pvma.vm_policy = spol; 1126 page = swapin_readahead(entry, gfp, &pvma, 0); 1127 return page; 1128} 1129 1130static struct page *shmem_alloc_page(gfp_t gfp, 1131 struct shmem_inode_info *info, unsigned long idx) 1132{ 1133 struct vm_area_struct pvma; 1134 1135 /* Create a pseudo vma that just contains the policy */ 1136 pvma.vm_start = 0; 1137 pvma.vm_pgoff = idx; 1138 pvma.vm_ops = NULL; 1139 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1140 1141 /* 1142 * alloc_page_vma() will drop the shared policy reference 1143 */ 1144 return alloc_page_vma(gfp, &pvma, 0); 1145} 1146#else /* !CONFIG_NUMA */ 1147#ifdef CONFIG_TMPFS 1148static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) 1149{ 1150} 1151#endif /* CONFIG_TMPFS */ 1152 1153static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1154 struct shmem_inode_info *info, unsigned long idx) 1155{ 1156 return swapin_readahead(entry, gfp, NULL, 0); 1157} 1158 1159static inline struct page *shmem_alloc_page(gfp_t gfp, 1160 struct shmem_inode_info *info, unsigned long idx) 1161{ 1162 return alloc_page(gfp); 1163} 1164#endif /* CONFIG_NUMA */ 1165 1166#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) 1167static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1168{ 1169 return NULL; 1170} 1171#endif 1172 1173/* 1174 * shmem_getpage - either get the page from swap or allocate a new one 1175 * 1176 * If we allocate a new one we do not mark it dirty. That's up to the 1177 * vm. If we swap it in we mark it dirty since we also free the swap 1178 * entry since a page cannot live in both the swap and page cache 1179 */ 1180static int shmem_getpage(struct inode *inode, unsigned long idx, 1181 struct page **pagep, enum sgp_type sgp, int *type) 1182{ 1183 struct address_space *mapping = inode->i_mapping; 1184 struct shmem_inode_info *info = SHMEM_I(inode); 1185 struct shmem_sb_info *sbinfo; 1186 struct page *filepage = *pagep; 1187 struct page *swappage; 1188 swp_entry_t *entry; 1189 swp_entry_t swap; 1190 gfp_t gfp; 1191 int error; 1192 1193 if (idx >= SHMEM_MAX_INDEX) 1194 return -EFBIG; 1195 1196 if (type) 1197 *type = 0; 1198 1199 /* 1200 * Normally, filepage is NULL on entry, and either found 1201 * uptodate immediately, or allocated and zeroed, or read 1202 * in under swappage, which is then assigned to filepage. 1203 * But shmem_readpage (required for splice) passes in a locked 1204 * filepage, which may be found not uptodate by other callers 1205 * too, and may need to be copied from the swappage read in. 1206 */ 1207repeat: 1208 if (!filepage) 1209 filepage = find_lock_page(mapping, idx); 1210 if (filepage && PageUptodate(filepage)) 1211 goto done; 1212 error = 0; 1213 gfp = mapping_gfp_mask(mapping); 1214 if (!filepage) { 1215 /* 1216 * Try to preload while we can wait, to not make a habit of 1217 * draining atomic reserves; but don't latch on to this cpu. 1218 */ 1219 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1220 if (error) 1221 goto failed; 1222 radix_tree_preload_end(); 1223 } 1224 1225 spin_lock(&info->lock); 1226 shmem_recalc_inode(inode); 1227 entry = shmem_swp_alloc(info, idx, sgp); 1228 if (IS_ERR(entry)) { 1229 spin_unlock(&info->lock); 1230 error = PTR_ERR(entry); 1231 goto failed; 1232 } 1233 swap = *entry; 1234 1235 if (swap.val) { 1236 /* Look it up and read it in.. */ 1237 swappage = lookup_swap_cache(swap); 1238 if (!swappage) { 1239 shmem_swp_unmap(entry); 1240 /* here we actually do the io */ 1241 if (type && !(*type & VM_FAULT_MAJOR)) { 1242 __count_vm_event(PGMAJFAULT); 1243 *type |= VM_FAULT_MAJOR; 1244 } 1245 spin_unlock(&info->lock); 1246 swappage = shmem_swapin(swap, gfp, info, idx); 1247 if (!swappage) { 1248 spin_lock(&info->lock); 1249 entry = shmem_swp_alloc(info, idx, sgp); 1250 if (IS_ERR(entry)) 1251 error = PTR_ERR(entry); 1252 else { 1253 if (entry->val == swap.val) 1254 error = -ENOMEM; 1255 shmem_swp_unmap(entry); 1256 } 1257 spin_unlock(&info->lock); 1258 if (error) 1259 goto failed; 1260 goto repeat; 1261 } 1262 wait_on_page_locked(swappage); 1263 page_cache_release(swappage); 1264 goto repeat; 1265 } 1266 1267 /* We have to do this with page locked to prevent races */ 1268 if (TestSetPageLocked(swappage)) { 1269 shmem_swp_unmap(entry); 1270 spin_unlock(&info->lock); 1271 wait_on_page_locked(swappage); 1272 page_cache_release(swappage); 1273 goto repeat; 1274 } 1275 if (PageWriteback(swappage)) { 1276 shmem_swp_unmap(entry); 1277 spin_unlock(&info->lock); 1278 wait_on_page_writeback(swappage); 1279 unlock_page(swappage); 1280 page_cache_release(swappage); 1281 goto repeat; 1282 } 1283 if (!PageUptodate(swappage)) { 1284 shmem_swp_unmap(entry); 1285 spin_unlock(&info->lock); 1286 unlock_page(swappage); 1287 page_cache_release(swappage); 1288 error = -EIO; 1289 goto failed; 1290 } 1291 1292 if (filepage) { 1293 shmem_swp_set(info, entry, 0); 1294 shmem_swp_unmap(entry); 1295 delete_from_swap_cache(swappage); 1296 spin_unlock(&info->lock); 1297 copy_highpage(filepage, swappage); 1298 unlock_page(swappage); 1299 page_cache_release(swappage); 1300 flush_dcache_page(filepage); 1301 SetPageUptodate(filepage); 1302 set_page_dirty(filepage); 1303 swap_free(swap); 1304 } else if (!(error = add_to_page_cache( 1305 swappage, mapping, idx, GFP_NOWAIT))) { 1306 info->flags |= SHMEM_PAGEIN; 1307 shmem_swp_set(info, entry, 0); 1308 shmem_swp_unmap(entry); 1309 delete_from_swap_cache(swappage); 1310 spin_unlock(&info->lock); 1311 filepage = swappage; 1312 set_page_dirty(filepage); 1313 swap_free(swap); 1314 } else { 1315 shmem_swp_unmap(entry); 1316 spin_unlock(&info->lock); 1317 unlock_page(swappage); 1318 if (error == -ENOMEM) { 1319 /* allow reclaim from this memory cgroup */ 1320 error = mem_cgroup_cache_charge(swappage, 1321 current->mm, gfp & ~__GFP_HIGHMEM); 1322 if (error) { 1323 page_cache_release(swappage); 1324 goto failed; 1325 } 1326 mem_cgroup_uncharge_cache_page(swappage); 1327 } 1328 page_cache_release(swappage); 1329 goto repeat; 1330 } 1331 } else if (sgp == SGP_READ && !filepage) { 1332 shmem_swp_unmap(entry); 1333 filepage = find_get_page(mapping, idx); 1334 if (filepage && 1335 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1336 spin_unlock(&info->lock); 1337 wait_on_page_locked(filepage); 1338 page_cache_release(filepage); 1339 filepage = NULL; 1340 goto repeat; 1341 } 1342 spin_unlock(&info->lock); 1343 } else { 1344 shmem_swp_unmap(entry); 1345 sbinfo = SHMEM_SB(inode->i_sb); 1346 if (sbinfo->max_blocks) { 1347 spin_lock(&sbinfo->stat_lock); 1348 if (sbinfo->free_blocks == 0 || 1349 shmem_acct_block(info->flags)) { 1350 spin_unlock(&sbinfo->stat_lock); 1351 spin_unlock(&info->lock); 1352 error = -ENOSPC; 1353 goto failed; 1354 } 1355 sbinfo->free_blocks--; 1356 inode->i_blocks += BLOCKS_PER_PAGE; 1357 spin_unlock(&sbinfo->stat_lock); 1358 } else if (shmem_acct_block(info->flags)) { 1359 spin_unlock(&info->lock); 1360 error = -ENOSPC; 1361 goto failed; 1362 } 1363 1364 if (!filepage) { 1365 int ret; 1366 1367 spin_unlock(&info->lock); 1368 filepage = shmem_alloc_page(gfp, info, idx); 1369 if (!filepage) { 1370 shmem_unacct_blocks(info->flags, 1); 1371 shmem_free_blocks(inode, 1); 1372 error = -ENOMEM; 1373 goto failed; 1374 } 1375 1376 /* Precharge page while we can wait, compensate after */ 1377 error = mem_cgroup_cache_charge(filepage, current->mm, 1378 gfp & ~__GFP_HIGHMEM); 1379 if (error) { 1380 page_cache_release(filepage); 1381 shmem_unacct_blocks(info->flags, 1); 1382 shmem_free_blocks(inode, 1); 1383 filepage = NULL; 1384 goto failed; 1385 } 1386 1387 spin_lock(&info->lock); 1388 entry = shmem_swp_alloc(info, idx, sgp); 1389 if (IS_ERR(entry)) 1390 error = PTR_ERR(entry); 1391 else { 1392 swap = *entry; 1393 shmem_swp_unmap(entry); 1394 } 1395 ret = error || swap.val; 1396 if (ret) 1397 mem_cgroup_uncharge_cache_page(filepage); 1398 else 1399 ret = add_to_page_cache_lru(filepage, mapping, 1400 idx, GFP_NOWAIT); 1401 /* 1402 * At add_to_page_cache_lru() failure, uncharge will 1403 * be done automatically. 1404 */ 1405 if (ret) { 1406 spin_unlock(&info->lock); 1407 page_cache_release(filepage); 1408 shmem_unacct_blocks(info->flags, 1); 1409 shmem_free_blocks(inode, 1); 1410 filepage = NULL; 1411 if (error) 1412 goto failed; 1413 goto repeat; 1414 } 1415 info->flags |= SHMEM_PAGEIN; 1416 } 1417 1418 info->alloced++; 1419 spin_unlock(&info->lock); 1420 clear_highpage(filepage); 1421 flush_dcache_page(filepage); 1422 SetPageUptodate(filepage); 1423 if (sgp == SGP_DIRTY) 1424 set_page_dirty(filepage); 1425 } 1426done: 1427 *pagep = filepage; 1428 return 0; 1429 1430failed: 1431 if (*pagep != filepage) { 1432 unlock_page(filepage); 1433 page_cache_release(filepage); 1434 } 1435 return error; 1436} 1437 1438static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1439{ 1440 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1441 int error; 1442 int ret; 1443 1444 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1445 return VM_FAULT_SIGBUS; 1446 1447 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1448 if (error) 1449 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1450 1451 mark_page_accessed(vmf->page); 1452 return ret | VM_FAULT_LOCKED; 1453} 1454 1455#ifdef CONFIG_NUMA 1456static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1457{ 1458 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1459 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1460} 1461 1462static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1463 unsigned long addr) 1464{ 1465 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1466 unsigned long idx; 1467 1468 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1469 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1470} 1471#endif 1472 1473int shmem_lock(struct file *file, int lock, struct user_struct *user) 1474{ 1475 struct inode *inode = file->f_path.dentry->d_inode; 1476 struct shmem_inode_info *info = SHMEM_I(inode); 1477 int retval = -ENOMEM; 1478 1479 spin_lock(&info->lock); 1480 if (lock && !(info->flags & VM_LOCKED)) { 1481 if (!user_shm_lock(inode->i_size, user)) 1482 goto out_nomem; 1483 info->flags |= VM_LOCKED; 1484 } 1485 if (!lock && (info->flags & VM_LOCKED) && user) { 1486 user_shm_unlock(inode->i_size, user); 1487 info->flags &= ~VM_LOCKED; 1488 } 1489 retval = 0; 1490out_nomem: 1491 spin_unlock(&info->lock); 1492 return retval; 1493} 1494 1495static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1496{ 1497 file_accessed(file); 1498 vma->vm_ops = &shmem_vm_ops; 1499 vma->vm_flags |= VM_CAN_NONLINEAR; 1500 return 0; 1501} 1502 1503static struct inode * 1504shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1505{ 1506 struct inode *inode; 1507 struct shmem_inode_info *info; 1508 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1509 1510 if (shmem_reserve_inode(sb)) 1511 return NULL; 1512 1513 inode = new_inode(sb); 1514 if (inode) { 1515 inode->i_mode = mode; 1516 inode->i_uid = current->fsuid; 1517 inode->i_gid = current->fsgid; 1518 inode->i_blocks = 0; 1519 inode->i_mapping->a_ops = &shmem_aops; 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_op = &shmem_inode_operations; 1535 inode->i_fop = &shmem_file_operations; 1536 mpol_shared_policy_init(&info->policy, 1537 shmem_get_sbmpol(sbinfo)); 1538 break; 1539 case S_IFDIR: 1540 inc_nlink(inode); 1541 /* Some things misbehave if size == 0 on a directory */ 1542 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1543 inode->i_op = &shmem_dir_inode_operations; 1544 inode->i_fop = &simple_dir_operations; 1545 break; 1546 case S_IFLNK: 1547 /* 1548 * Must not load anything in the rbtree, 1549 * mpol_free_shared_policy will not be called. 1550 */ 1551 mpol_shared_policy_init(&info->policy, NULL); 1552 break; 1553 } 1554 } else 1555 shmem_free_inode(sb); 1556 return inode; 1557} 1558 1559#ifdef CONFIG_TMPFS 1560static const struct inode_operations shmem_symlink_inode_operations; 1561static const struct inode_operations shmem_symlink_inline_operations; 1562 1563/* 1564 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1565 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1566 * below the loop driver, in the generic fashion that many filesystems support. 1567 */ 1568static int shmem_readpage(struct file *file, struct page *page) 1569{ 1570 struct inode *inode = page->mapping->host; 1571 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1572 unlock_page(page); 1573 return error; 1574} 1575 1576static int 1577shmem_write_begin(struct file *file, struct address_space *mapping, 1578 loff_t pos, unsigned len, unsigned flags, 1579 struct page **pagep, void **fsdata) 1580{ 1581 struct inode *inode = mapping->host; 1582 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1583 *pagep = NULL; 1584 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1585} 1586 1587static int 1588shmem_write_end(struct file *file, struct address_space *mapping, 1589 loff_t pos, unsigned len, unsigned copied, 1590 struct page *page, void *fsdata) 1591{ 1592 struct inode *inode = mapping->host; 1593 1594 if (pos + copied > inode->i_size) 1595 i_size_write(inode, pos + copied); 1596 1597 unlock_page(page); 1598 set_page_dirty(page); 1599 page_cache_release(page); 1600 1601 return copied; 1602} 1603 1604static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1605{ 1606 struct inode *inode = filp->f_path.dentry->d_inode; 1607 struct address_space *mapping = inode->i_mapping; 1608 unsigned long index, offset; 1609 enum sgp_type sgp = SGP_READ; 1610 1611 /* 1612 * Might this read be for a stacking filesystem? Then when reading 1613 * holes of a sparse file, we actually need to allocate those pages, 1614 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1615 */ 1616 if (segment_eq(get_fs(), KERNEL_DS)) 1617 sgp = SGP_DIRTY; 1618 1619 index = *ppos >> PAGE_CACHE_SHIFT; 1620 offset = *ppos & ~PAGE_CACHE_MASK; 1621 1622 for (;;) { 1623 struct page *page = NULL; 1624 unsigned long end_index, nr, ret; 1625 loff_t i_size = i_size_read(inode); 1626 1627 end_index = i_size >> PAGE_CACHE_SHIFT; 1628 if (index > end_index) 1629 break; 1630 if (index == end_index) { 1631 nr = i_size & ~PAGE_CACHE_MASK; 1632 if (nr <= offset) 1633 break; 1634 } 1635 1636 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1637 if (desc->error) { 1638 if (desc->error == -EINVAL) 1639 desc->error = 0; 1640 break; 1641 } 1642 if (page) 1643 unlock_page(page); 1644 1645 /* 1646 * We must evaluate after, since reads (unlike writes) 1647 * are called without i_mutex protection against truncate 1648 */ 1649 nr = PAGE_CACHE_SIZE; 1650 i_size = i_size_read(inode); 1651 end_index = i_size >> PAGE_CACHE_SHIFT; 1652 if (index == end_index) { 1653 nr = i_size & ~PAGE_CACHE_MASK; 1654 if (nr <= offset) { 1655 if (page) 1656 page_cache_release(page); 1657 break; 1658 } 1659 } 1660 nr -= offset; 1661 1662 if (page) { 1663 /* 1664 * If users can be writing to this page using arbitrary 1665 * virtual addresses, take care about potential aliasing 1666 * before reading the page on the kernel side. 1667 */ 1668 if (mapping_writably_mapped(mapping)) 1669 flush_dcache_page(page); 1670 /* 1671 * Mark the page accessed if we read the beginning. 1672 */ 1673 if (!offset) 1674 mark_page_accessed(page); 1675 } else { 1676 page = ZERO_PAGE(0); 1677 page_cache_get(page); 1678 } 1679 1680 /* 1681 * Ok, we have the page, and it's up-to-date, so 1682 * now we can copy it to user space... 1683 * 1684 * The actor routine returns how many bytes were actually used.. 1685 * NOTE! This may not be the same as how much of a user buffer 1686 * we filled up (we may be padding etc), so we can only update 1687 * "pos" here (the actor routine has to update the user buffer 1688 * pointers and the remaining count). 1689 */ 1690 ret = actor(desc, page, offset, nr); 1691 offset += ret; 1692 index += offset >> PAGE_CACHE_SHIFT; 1693 offset &= ~PAGE_CACHE_MASK; 1694 1695 page_cache_release(page); 1696 if (ret != nr || !desc->count) 1697 break; 1698 1699 cond_resched(); 1700 } 1701 1702 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1703 file_accessed(filp); 1704} 1705 1706static ssize_t shmem_file_aio_read(struct kiocb *iocb, 1707 const struct iovec *iov, unsigned long nr_segs, loff_t pos) 1708{ 1709 struct file *filp = iocb->ki_filp; 1710 ssize_t retval; 1711 unsigned long seg; 1712 size_t count; 1713 loff_t *ppos = &iocb->ki_pos; 1714 1715 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); 1716 if (retval) 1717 return retval; 1718 1719 for (seg = 0; seg < nr_segs; seg++) { 1720 read_descriptor_t desc; 1721 1722 desc.written = 0; 1723 desc.arg.buf = iov[seg].iov_base; 1724 desc.count = iov[seg].iov_len; 1725 if (desc.count == 0) 1726 continue; 1727 desc.error = 0; 1728 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1729 retval += desc.written; 1730 if (desc.error) { 1731 retval = retval ?: desc.error; 1732 break; 1733 } 1734 if (desc.count > 0) 1735 break; 1736 } 1737 return retval; 1738} 1739 1740static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1741{ 1742 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1743 1744 buf->f_type = TMPFS_MAGIC; 1745 buf->f_bsize = PAGE_CACHE_SIZE; 1746 buf->f_namelen = NAME_MAX; 1747 spin_lock(&sbinfo->stat_lock); 1748 if (sbinfo->max_blocks) { 1749 buf->f_blocks = sbinfo->max_blocks; 1750 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1751 } 1752 if (sbinfo->max_inodes) { 1753 buf->f_files = sbinfo->max_inodes; 1754 buf->f_ffree = sbinfo->free_inodes; 1755 } 1756 /* else leave those fields 0 like simple_statfs */ 1757 spin_unlock(&sbinfo->stat_lock); 1758 return 0; 1759} 1760 1761/* 1762 * File creation. Allocate an inode, and we're done.. 1763 */ 1764static int 1765shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1766{ 1767 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1768 int error = -ENOSPC; 1769 1770 if (inode) { 1771 error = security_inode_init_security(inode, dir, NULL, NULL, 1772 NULL); 1773 if (error) { 1774 if (error != -EOPNOTSUPP) { 1775 iput(inode); 1776 return error; 1777 } 1778 } 1779 error = shmem_acl_init(inode, dir); 1780 if (error) { 1781 iput(inode); 1782 return error; 1783 } 1784 if (dir->i_mode & S_ISGID) { 1785 inode->i_gid = dir->i_gid; 1786 if (S_ISDIR(mode)) 1787 inode->i_mode |= S_ISGID; 1788 } 1789 dir->i_size += BOGO_DIRENT_SIZE; 1790 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1791 d_instantiate(dentry, inode); 1792 dget(dentry); /* Extra count - pin the dentry in core */ 1793 } 1794 return error; 1795} 1796 1797static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1798{ 1799 int error; 1800 1801 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1802 return error; 1803 inc_nlink(dir); 1804 return 0; 1805} 1806 1807static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1808 struct nameidata *nd) 1809{ 1810 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1811} 1812 1813/* 1814 * Link a file.. 1815 */ 1816static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1817{ 1818 struct inode *inode = old_dentry->d_inode; 1819 int ret; 1820 1821 /* 1822 * No ordinary (disk based) filesystem counts links as inodes; 1823 * but each new link needs a new dentry, pinning lowmem, and 1824 * tmpfs dentries cannot be pruned until they are unlinked. 1825 */ 1826 ret = shmem_reserve_inode(inode->i_sb); 1827 if (ret) 1828 goto out; 1829 1830 dir->i_size += BOGO_DIRENT_SIZE; 1831 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1832 inc_nlink(inode); 1833 atomic_inc(&inode->i_count); /* New dentry reference */ 1834 dget(dentry); /* Extra pinning count for the created dentry */ 1835 d_instantiate(dentry, inode); 1836out: 1837 return ret; 1838} 1839 1840static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1841{ 1842 struct inode *inode = dentry->d_inode; 1843 1844 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1845 shmem_free_inode(inode->i_sb); 1846 1847 dir->i_size -= BOGO_DIRENT_SIZE; 1848 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1849 drop_nlink(inode); 1850 dput(dentry); /* Undo the count from "create" - this does all the work */ 1851 return 0; 1852} 1853 1854static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1855{ 1856 if (!simple_empty(dentry)) 1857 return -ENOTEMPTY; 1858 1859 drop_nlink(dentry->d_inode); 1860 drop_nlink(dir); 1861 return shmem_unlink(dir, dentry); 1862} 1863 1864/* 1865 * The VFS layer already does all the dentry stuff for rename, 1866 * we just have to decrement the usage count for the target if 1867 * it exists so that the VFS layer correctly free's it when it 1868 * gets overwritten. 1869 */ 1870static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1871{ 1872 struct inode *inode = old_dentry->d_inode; 1873 int they_are_dirs = S_ISDIR(inode->i_mode); 1874 1875 if (!simple_empty(new_dentry)) 1876 return -ENOTEMPTY; 1877 1878 if (new_dentry->d_inode) { 1879 (void) shmem_unlink(new_dir, new_dentry); 1880 if (they_are_dirs) 1881 drop_nlink(old_dir); 1882 } else if (they_are_dirs) { 1883 drop_nlink(old_dir); 1884 inc_nlink(new_dir); 1885 } 1886 1887 old_dir->i_size -= BOGO_DIRENT_SIZE; 1888 new_dir->i_size += BOGO_DIRENT_SIZE; 1889 old_dir->i_ctime = old_dir->i_mtime = 1890 new_dir->i_ctime = new_dir->i_mtime = 1891 inode->i_ctime = CURRENT_TIME; 1892 return 0; 1893} 1894 1895static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1896{ 1897 int error; 1898 int len; 1899 struct inode *inode; 1900 struct page *page = NULL; 1901 char *kaddr; 1902 struct shmem_inode_info *info; 1903 1904 len = strlen(symname) + 1; 1905 if (len > PAGE_CACHE_SIZE) 1906 return -ENAMETOOLONG; 1907 1908 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1909 if (!inode) 1910 return -ENOSPC; 1911 1912 error = security_inode_init_security(inode, dir, NULL, NULL, 1913 NULL); 1914 if (error) { 1915 if (error != -EOPNOTSUPP) { 1916 iput(inode); 1917 return error; 1918 } 1919 error = 0; 1920 } 1921 1922 info = SHMEM_I(inode); 1923 inode->i_size = len-1; 1924 if (len <= (char *)inode - (char *)info) { 1925 /* do it inline */ 1926 memcpy(info, symname, len); 1927 inode->i_op = &shmem_symlink_inline_operations; 1928 } else { 1929 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1930 if (error) { 1931 iput(inode); 1932 return error; 1933 } 1934 unlock_page(page); 1935 inode->i_op = &shmem_symlink_inode_operations; 1936 kaddr = kmap_atomic(page, KM_USER0); 1937 memcpy(kaddr, symname, len); 1938 kunmap_atomic(kaddr, KM_USER0); 1939 set_page_dirty(page); 1940 page_cache_release(page); 1941 } 1942 if (dir->i_mode & S_ISGID) 1943 inode->i_gid = dir->i_gid; 1944 dir->i_size += BOGO_DIRENT_SIZE; 1945 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1946 d_instantiate(dentry, inode); 1947 dget(dentry); 1948 return 0; 1949} 1950 1951static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1952{ 1953 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1954 return NULL; 1955} 1956 1957static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1958{ 1959 struct page *page = NULL; 1960 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1961 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1962 if (page) 1963 unlock_page(page); 1964 return page; 1965} 1966 1967static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1968{ 1969 if (!IS_ERR(nd_get_link(nd))) { 1970 struct page *page = cookie; 1971 kunmap(page); 1972 mark_page_accessed(page); 1973 page_cache_release(page); 1974 } 1975} 1976 1977static const struct inode_operations shmem_symlink_inline_operations = { 1978 .readlink = generic_readlink, 1979 .follow_link = shmem_follow_link_inline, 1980}; 1981 1982static const struct inode_operations shmem_symlink_inode_operations = { 1983 .truncate = shmem_truncate, 1984 .readlink = generic_readlink, 1985 .follow_link = shmem_follow_link, 1986 .put_link = shmem_put_link, 1987}; 1988 1989#ifdef CONFIG_TMPFS_POSIX_ACL 1990/* 1991 * Superblocks without xattr inode operations will get security.* xattr 1992 * support from the VFS "for free". As soon as we have any other xattrs 1993 * like ACLs, we also need to implement the security.* handlers at 1994 * filesystem level, though. 1995 */ 1996 1997static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1998 size_t list_len, const char *name, 1999 size_t name_len) 2000{ 2001 return security_inode_listsecurity(inode, list, list_len); 2002} 2003 2004static int shmem_xattr_security_get(struct inode *inode, const char *name, 2005 void *buffer, size_t size) 2006{ 2007 if (strcmp(name, "") == 0) 2008 return -EINVAL; 2009 return xattr_getsecurity(inode, name, buffer, size); 2010} 2011 2012static int shmem_xattr_security_set(struct inode *inode, const char *name, 2013 const void *value, size_t size, int flags) 2014{ 2015 if (strcmp(name, "") == 0) 2016 return -EINVAL; 2017 return security_inode_setsecurity(inode, name, value, size, flags); 2018} 2019 2020static struct xattr_handler shmem_xattr_security_handler = { 2021 .prefix = XATTR_SECURITY_PREFIX, 2022 .list = shmem_xattr_security_list, 2023 .get = shmem_xattr_security_get, 2024 .set = shmem_xattr_security_set, 2025}; 2026 2027static struct xattr_handler *shmem_xattr_handlers[] = { 2028 &shmem_xattr_acl_access_handler, 2029 &shmem_xattr_acl_default_handler, 2030 &shmem_xattr_security_handler, 2031 NULL 2032}; 2033#endif 2034 2035static struct dentry *shmem_get_parent(struct dentry *child) 2036{ 2037 return ERR_PTR(-ESTALE); 2038} 2039 2040static int shmem_match(struct inode *ino, void *vfh) 2041{ 2042 __u32 *fh = vfh; 2043 __u64 inum = fh[2]; 2044 inum = (inum << 32) | fh[1]; 2045 return ino->i_ino == inum && fh[0] == ino->i_generation; 2046} 2047 2048static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2049 struct fid *fid, int fh_len, int fh_type) 2050{ 2051 struct inode *inode; 2052 struct dentry *dentry = NULL; 2053 u64 inum = fid->raw[2]; 2054 inum = (inum << 32) | fid->raw[1]; 2055 2056 if (fh_len < 3) 2057 return NULL; 2058 2059 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2060 shmem_match, fid->raw); 2061 if (inode) { 2062 dentry = d_find_alias(inode); 2063 iput(inode); 2064 } 2065 2066 return dentry; 2067} 2068 2069static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2070 int connectable) 2071{ 2072 struct inode *inode = dentry->d_inode; 2073 2074 if (*len < 3) 2075 return 255; 2076 2077 if (hlist_unhashed(&inode->i_hash)) { 2078 /* Unfortunately insert_inode_hash is not idempotent, 2079 * so as we hash inodes here rather than at creation 2080 * time, we need a lock to ensure we only try 2081 * to do it once 2082 */ 2083 static DEFINE_SPINLOCK(lock); 2084 spin_lock(&lock); 2085 if (hlist_unhashed(&inode->i_hash)) 2086 __insert_inode_hash(inode, 2087 inode->i_ino + inode->i_generation); 2088 spin_unlock(&lock); 2089 } 2090 2091 fh[0] = inode->i_generation; 2092 fh[1] = inode->i_ino; 2093 fh[2] = ((__u64)inode->i_ino) >> 32; 2094 2095 *len = 3; 2096 return 1; 2097} 2098 2099static const struct export_operations shmem_export_ops = { 2100 .get_parent = shmem_get_parent, 2101 .encode_fh = shmem_encode_fh, 2102 .fh_to_dentry = shmem_fh_to_dentry, 2103}; 2104 2105static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 2106 bool remount) 2107{ 2108 char *this_char, *value, *rest; 2109 2110 while (options != NULL) { 2111 this_char = options; 2112 for (;;) { 2113 /* 2114 * NUL-terminate this option: unfortunately, 2115 * mount options form a comma-separated list, 2116 * but mpol's nodelist may also contain commas. 2117 */ 2118 options = strchr(options, ','); 2119 if (options == NULL) 2120 break; 2121 options++; 2122 if (!isdigit(*options)) { 2123 options[-1] = '\0'; 2124 break; 2125 } 2126 } 2127 if (!*this_char) 2128 continue; 2129 if ((value = strchr(this_char,'=')) != NULL) { 2130 *value++ = 0; 2131 } else { 2132 printk(KERN_ERR 2133 "tmpfs: No value for mount option '%s'\n", 2134 this_char); 2135 return 1; 2136 } 2137 2138 if (!strcmp(this_char,"size")) { 2139 unsigned long long size; 2140 size = memparse(value,&rest); 2141 if (*rest == '%') { 2142 size <<= PAGE_SHIFT; 2143 size *= totalram_pages; 2144 do_div(size, 100); 2145 rest++; 2146 } 2147 if (*rest) 2148 goto bad_val; 2149 sbinfo->max_blocks = 2150 DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2151 } else if (!strcmp(this_char,"nr_blocks")) { 2152 sbinfo->max_blocks = memparse(value, &rest); 2153 if (*rest) 2154 goto bad_val; 2155 } else if (!strcmp(this_char,"nr_inodes")) { 2156 sbinfo->max_inodes = memparse(value, &rest); 2157 if (*rest) 2158 goto bad_val; 2159 } else if (!strcmp(this_char,"mode")) { 2160 if (remount) 2161 continue; 2162 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; 2163 if (*rest) 2164 goto bad_val; 2165 } else if (!strcmp(this_char,"uid")) { 2166 if (remount) 2167 continue; 2168 sbinfo->uid = simple_strtoul(value, &rest, 0); 2169 if (*rest) 2170 goto bad_val; 2171 } else if (!strcmp(this_char,"gid")) { 2172 if (remount) 2173 continue; 2174 sbinfo->gid = simple_strtoul(value, &rest, 0); 2175 if (*rest) 2176 goto bad_val; 2177 } else if (!strcmp(this_char,"mpol")) { 2178 if (mpol_parse_str(value, &sbinfo->mpol, 1)) 2179 goto bad_val; 2180 } else { 2181 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2182 this_char); 2183 return 1; 2184 } 2185 } 2186 return 0; 2187 2188bad_val: 2189 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2190 value, this_char); 2191 return 1; 2192 2193} 2194 2195static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2196{ 2197 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2198 struct shmem_sb_info config = *sbinfo; 2199 unsigned long blocks; 2200 unsigned long inodes; 2201 int error = -EINVAL; 2202 2203 if (shmem_parse_options(data, &config, true)) 2204 return error; 2205 2206 spin_lock(&sbinfo->stat_lock); 2207 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2208 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2209 if (config.max_blocks < blocks) 2210 goto out; 2211 if (config.max_inodes < inodes) 2212 goto out; 2213 /* 2214 * Those tests also disallow limited->unlimited while any are in 2215 * use, so i_blocks will always be zero when max_blocks is zero; 2216 * but we must separately disallow unlimited->limited, because 2217 * in that case we have no record of how much is already in use. 2218 */ 2219 if (config.max_blocks && !sbinfo->max_blocks) 2220 goto out; 2221 if (config.max_inodes && !sbinfo->max_inodes) 2222 goto out; 2223 2224 error = 0; 2225 sbinfo->max_blocks = config.max_blocks; 2226 sbinfo->free_blocks = config.max_blocks - blocks; 2227 sbinfo->max_inodes = config.max_inodes; 2228 sbinfo->free_inodes = config.max_inodes - inodes; 2229 2230 mpol_put(sbinfo->mpol); 2231 sbinfo->mpol = config.mpol; /* transfers initial ref */ 2232out: 2233 spin_unlock(&sbinfo->stat_lock); 2234 return error; 2235} 2236 2237static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) 2238{ 2239 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); 2240 2241 if (sbinfo->max_blocks != shmem_default_max_blocks()) 2242 seq_printf(seq, ",size=%luk", 2243 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); 2244 if (sbinfo->max_inodes != shmem_default_max_inodes()) 2245 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); 2246 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) 2247 seq_printf(seq, ",mode=%03o", sbinfo->mode); 2248 if (sbinfo->uid != 0) 2249 seq_printf(seq, ",uid=%u", sbinfo->uid); 2250 if (sbinfo->gid != 0) 2251 seq_printf(seq, ",gid=%u", sbinfo->gid); 2252 shmem_show_mpol(seq, sbinfo->mpol); 2253 return 0; 2254} 2255#endif /* CONFIG_TMPFS */ 2256 2257static void shmem_put_super(struct super_block *sb) 2258{ 2259 kfree(sb->s_fs_info); 2260 sb->s_fs_info = NULL; 2261} 2262 2263static int shmem_fill_super(struct super_block *sb, 2264 void *data, int silent) 2265{ 2266 struct inode *inode; 2267 struct dentry *root; 2268 struct shmem_sb_info *sbinfo; 2269 int err = -ENOMEM; 2270 2271 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2272 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2273 L1_CACHE_BYTES), GFP_KERNEL); 2274 if (!sbinfo) 2275 return -ENOMEM; 2276 2277 sbinfo->max_blocks = 0; 2278 sbinfo->max_inodes = 0; 2279 sbinfo->mode = S_IRWXUGO | S_ISVTX; 2280 sbinfo->uid = current->fsuid; 2281 sbinfo->gid = current->fsgid; 2282 sbinfo->mpol = NULL; 2283 sb->s_fs_info = sbinfo; 2284 2285#ifdef CONFIG_TMPFS 2286 /* 2287 * Per default we only allow half of the physical ram per 2288 * tmpfs instance, limiting inodes to one per page of lowmem; 2289 * but the internal instance is left unlimited. 2290 */ 2291 if (!(sb->s_flags & MS_NOUSER)) { 2292 sbinfo->max_blocks = shmem_default_max_blocks(); 2293 sbinfo->max_inodes = shmem_default_max_inodes(); 2294 if (shmem_parse_options(data, sbinfo, false)) { 2295 err = -EINVAL; 2296 goto failed; 2297 } 2298 } 2299 sb->s_export_op = &shmem_export_ops; 2300#else 2301 sb->s_flags |= MS_NOUSER; 2302#endif 2303 2304 spin_lock_init(&sbinfo->stat_lock); 2305 sbinfo->free_blocks = sbinfo->max_blocks; 2306 sbinfo->free_inodes = sbinfo->max_inodes; 2307 2308 sb->s_maxbytes = SHMEM_MAX_BYTES; 2309 sb->s_blocksize = PAGE_CACHE_SIZE; 2310 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2311 sb->s_magic = TMPFS_MAGIC; 2312 sb->s_op = &shmem_ops; 2313 sb->s_time_gran = 1; 2314#ifdef CONFIG_TMPFS_POSIX_ACL 2315 sb->s_xattr = shmem_xattr_handlers; 2316 sb->s_flags |= MS_POSIXACL; 2317#endif 2318 2319 inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0); 2320 if (!inode) 2321 goto failed; 2322 inode->i_uid = sbinfo->uid; 2323 inode->i_gid = sbinfo->gid; 2324 root = d_alloc_root(inode); 2325 if (!root) 2326 goto failed_iput; 2327 sb->s_root = root; 2328 return 0; 2329 2330failed_iput: 2331 iput(inode); 2332failed: 2333 shmem_put_super(sb); 2334 return err; 2335} 2336 2337static struct kmem_cache *shmem_inode_cachep; 2338 2339static struct inode *shmem_alloc_inode(struct super_block *sb) 2340{ 2341 struct shmem_inode_info *p; 2342 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2343 if (!p) 2344 return NULL; 2345 return &p->vfs_inode; 2346} 2347 2348static void shmem_destroy_inode(struct inode *inode) 2349{ 2350 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2351 /* only struct inode is valid if it's an inline symlink */ 2352 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2353 } 2354 shmem_acl_destroy_inode(inode); 2355 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2356} 2357 2358static void init_once(struct kmem_cache *cachep, void *foo) 2359{ 2360 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2361 2362 inode_init_once(&p->vfs_inode); 2363#ifdef CONFIG_TMPFS_POSIX_ACL 2364 p->i_acl = NULL; 2365 p->i_default_acl = NULL; 2366#endif 2367} 2368 2369static int init_inodecache(void) 2370{ 2371 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2372 sizeof(struct shmem_inode_info), 2373 0, SLAB_PANIC, init_once); 2374 return 0; 2375} 2376 2377static void destroy_inodecache(void) 2378{ 2379 kmem_cache_destroy(shmem_inode_cachep); 2380} 2381 2382static const struct address_space_operations shmem_aops = { 2383 .writepage = shmem_writepage, 2384 .set_page_dirty = __set_page_dirty_no_writeback, 2385#ifdef CONFIG_TMPFS 2386 .readpage = shmem_readpage, 2387 .write_begin = shmem_write_begin, 2388 .write_end = shmem_write_end, 2389#endif 2390 .migratepage = migrate_page, 2391}; 2392 2393static const struct file_operations shmem_file_operations = { 2394 .mmap = shmem_mmap, 2395#ifdef CONFIG_TMPFS 2396 .llseek = generic_file_llseek, 2397 .read = do_sync_read, 2398 .write = do_sync_write, 2399 .aio_read = shmem_file_aio_read, 2400 .aio_write = generic_file_aio_write, 2401 .fsync = simple_sync_file, 2402 .splice_read = generic_file_splice_read, 2403 .splice_write = generic_file_splice_write, 2404#endif 2405}; 2406 2407static const struct inode_operations shmem_inode_operations = { 2408 .truncate = shmem_truncate, 2409 .setattr = shmem_notify_change, 2410 .truncate_range = shmem_truncate_range, 2411#ifdef CONFIG_TMPFS_POSIX_ACL 2412 .setxattr = generic_setxattr, 2413 .getxattr = generic_getxattr, 2414 .listxattr = generic_listxattr, 2415 .removexattr = generic_removexattr, 2416 .permission = shmem_permission, 2417#endif 2418 2419}; 2420 2421static const struct inode_operations shmem_dir_inode_operations = { 2422#ifdef CONFIG_TMPFS 2423 .create = shmem_create, 2424 .lookup = simple_lookup, 2425 .link = shmem_link, 2426 .unlink = shmem_unlink, 2427 .symlink = shmem_symlink, 2428 .mkdir = shmem_mkdir, 2429 .rmdir = shmem_rmdir, 2430 .mknod = shmem_mknod, 2431 .rename = shmem_rename, 2432#endif 2433#ifdef CONFIG_TMPFS_POSIX_ACL 2434 .setattr = shmem_notify_change, 2435 .setxattr = generic_setxattr, 2436 .getxattr = generic_getxattr, 2437 .listxattr = generic_listxattr, 2438 .removexattr = generic_removexattr, 2439 .permission = shmem_permission, 2440#endif 2441}; 2442 2443static const struct inode_operations shmem_special_inode_operations = { 2444#ifdef CONFIG_TMPFS_POSIX_ACL 2445 .setattr = shmem_notify_change, 2446 .setxattr = generic_setxattr, 2447 .getxattr = generic_getxattr, 2448 .listxattr = generic_listxattr, 2449 .removexattr = generic_removexattr, 2450 .permission = shmem_permission, 2451#endif 2452}; 2453 2454static const struct super_operations shmem_ops = { 2455 .alloc_inode = shmem_alloc_inode, 2456 .destroy_inode = shmem_destroy_inode, 2457#ifdef CONFIG_TMPFS 2458 .statfs = shmem_statfs, 2459 .remount_fs = shmem_remount_fs, 2460 .show_options = shmem_show_options, 2461#endif 2462 .delete_inode = shmem_delete_inode, 2463 .drop_inode = generic_delete_inode, 2464 .put_super = shmem_put_super, 2465}; 2466 2467static struct vm_operations_struct shmem_vm_ops = { 2468 .fault = shmem_fault, 2469#ifdef CONFIG_NUMA 2470 .set_policy = shmem_set_policy, 2471 .get_policy = shmem_get_policy, 2472#endif 2473}; 2474 2475 2476static int shmem_get_sb(struct file_system_type *fs_type, 2477 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2478{ 2479 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2480} 2481 2482static struct file_system_type tmpfs_fs_type = { 2483 .owner = THIS_MODULE, 2484 .name = "tmpfs", 2485 .get_sb = shmem_get_sb, 2486 .kill_sb = kill_litter_super, 2487}; 2488static struct vfsmount *shm_mnt; 2489 2490static int __init init_tmpfs(void) 2491{ 2492 int error; 2493 2494 error = bdi_init(&shmem_backing_dev_info); 2495 if (error) 2496 goto out4; 2497 2498 error = init_inodecache(); 2499 if (error) 2500 goto out3; 2501 2502 error = register_filesystem(&tmpfs_fs_type); 2503 if (error) { 2504 printk(KERN_ERR "Could not register tmpfs\n"); 2505 goto out2; 2506 } 2507 2508 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2509 tmpfs_fs_type.name, NULL); 2510 if (IS_ERR(shm_mnt)) { 2511 error = PTR_ERR(shm_mnt); 2512 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2513 goto out1; 2514 } 2515 return 0; 2516 2517out1: 2518 unregister_filesystem(&tmpfs_fs_type); 2519out2: 2520 destroy_inodecache(); 2521out3: 2522 bdi_destroy(&shmem_backing_dev_info); 2523out4: 2524 shm_mnt = ERR_PTR(error); 2525 return error; 2526} 2527module_init(init_tmpfs) 2528 2529/** 2530 * shmem_file_setup - get an unlinked file living in tmpfs 2531 * @name: name for dentry (to be seen in /proc/<pid>/maps 2532 * @size: size to be set for the file 2533 * @flags: vm_flags 2534 */ 2535struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2536{ 2537 int error; 2538 struct file *file; 2539 struct inode *inode; 2540 struct dentry *dentry, *root; 2541 struct qstr this; 2542 2543 if (IS_ERR(shm_mnt)) 2544 return (void *)shm_mnt; 2545 2546 if (size < 0 || size > SHMEM_MAX_BYTES) 2547 return ERR_PTR(-EINVAL); 2548 2549 if (shmem_acct_size(flags, size)) 2550 return ERR_PTR(-ENOMEM); 2551 2552 error = -ENOMEM; 2553 this.name = name; 2554 this.len = strlen(name); 2555 this.hash = 0; /* will go */ 2556 root = shm_mnt->mnt_root; 2557 dentry = d_alloc(root, &this); 2558 if (!dentry) 2559 goto put_memory; 2560 2561 error = -ENFILE; 2562 file = get_empty_filp(); 2563 if (!file) 2564 goto put_dentry; 2565 2566 error = -ENOSPC; 2567 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2568 if (!inode) 2569 goto close_file; 2570 2571 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2572 d_instantiate(dentry, inode); 2573 inode->i_size = size; 2574 inode->i_nlink = 0; /* It is unlinked */ 2575 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ, 2576 &shmem_file_operations); 2577 return file; 2578 2579close_file: 2580 put_filp(file); 2581put_dentry: 2582 dput(dentry); 2583put_memory: 2584 shmem_unacct_size(flags, size); 2585 return ERR_PTR(error); 2586} 2587 2588/** 2589 * shmem_zero_setup - setup a shared anonymous mapping 2590 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2591 */ 2592int shmem_zero_setup(struct vm_area_struct *vma) 2593{ 2594 struct file *file; 2595 loff_t size = vma->vm_end - vma->vm_start; 2596 2597 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2598 if (IS_ERR(file)) 2599 return PTR_ERR(file); 2600 2601 if (vma->vm_file) 2602 fput(vma->vm_file); 2603 vma->vm_file = file; 2604 vma->vm_ops = &shmem_vm_ops; 2605 return 0; 2606} 2607