shmem.c revision 02098feaa42b2e0087fbbe6c6ab9a23e4653b16a
1/* 2 * Resizable virtual memory filesystem for Linux. 3 * 4 * Copyright (C) 2000 Linus Torvalds. 5 * 2000 Transmeta Corp. 6 * 2000-2001 Christoph Rohland 7 * 2000-2001 SAP AG 8 * 2002 Red Hat Inc. 9 * Copyright (C) 2002-2005 Hugh Dickins. 10 * Copyright (C) 2002-2005 VERITAS Software Corporation. 11 * Copyright (C) 2004 Andi Kleen, SuSE Labs 12 * 13 * Extended attribute support for tmpfs: 14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> 15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> 16 * 17 * This file is released under the GPL. 18 */ 19 20/* 21 * This virtual memory filesystem is heavily based on the ramfs. It 22 * extends ramfs by the ability to use swap and honor resource limits 23 * which makes it a completely usable filesystem. 24 */ 25 26#include <linux/module.h> 27#include <linux/init.h> 28#include <linux/fs.h> 29#include <linux/xattr.h> 30#include <linux/exportfs.h> 31#include <linux/generic_acl.h> 32#include <linux/mm.h> 33#include <linux/mman.h> 34#include <linux/file.h> 35#include <linux/swap.h> 36#include <linux/pagemap.h> 37#include <linux/string.h> 38#include <linux/slab.h> 39#include <linux/backing-dev.h> 40#include <linux/shmem_fs.h> 41#include <linux/mount.h> 42#include <linux/writeback.h> 43#include <linux/vfs.h> 44#include <linux/blkdev.h> 45#include <linux/security.h> 46#include <linux/swapops.h> 47#include <linux/mempolicy.h> 48#include <linux/namei.h> 49#include <linux/ctype.h> 50#include <linux/migrate.h> 51#include <linux/highmem.h> 52 53#include <asm/uaccess.h> 54#include <asm/div64.h> 55#include <asm/pgtable.h> 56 57/* This magic number is used in glibc for posix shared memory */ 58#define TMPFS_MAGIC 0x01021994 59 60#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 61#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 62#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 63 64#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 65#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 66 67#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 68 69/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 70#define SHMEM_PAGEIN VM_READ 71#define SHMEM_TRUNCATE VM_WRITE 72 73/* Definition to limit shmem_truncate's steps between cond_rescheds */ 74#define LATENCY_LIMIT 64 75 76/* Pretend that each entry is of this size in directory's i_size */ 77#define BOGO_DIRENT_SIZE 20 78 79/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 80enum sgp_type { 81 SGP_QUICK, /* don't try more than file page cache lookup */ 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_WRITE, /* may exceed i_size, may allocate page */ 85 SGP_FAULT, /* same as SGP_CACHE, return with page locked */ 86}; 87 88static int shmem_getpage(struct inode *inode, unsigned long idx, 89 struct page **pagep, enum sgp_type sgp, int *type); 90 91static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 92{ 93 /* 94 * The above definition of ENTRIES_PER_PAGE, and the use of 95 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 96 * might be reconsidered if it ever diverges from PAGE_SIZE. 97 * 98 * Mobility flags are masked out as swap vectors cannot move 99 */ 100 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, 101 PAGE_CACHE_SHIFT-PAGE_SHIFT); 102} 103 104static inline void shmem_dir_free(struct page *page) 105{ 106 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 107} 108 109static struct page **shmem_dir_map(struct page *page) 110{ 111 return (struct page **)kmap_atomic(page, KM_USER0); 112} 113 114static inline void shmem_dir_unmap(struct page **dir) 115{ 116 kunmap_atomic(dir, KM_USER0); 117} 118 119static swp_entry_t *shmem_swp_map(struct page *page) 120{ 121 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 122} 123 124static inline void shmem_swp_balance_unmap(void) 125{ 126 /* 127 * When passing a pointer to an i_direct entry, to code which 128 * also handles indirect entries and so will shmem_swp_unmap, 129 * we must arrange for the preempt count to remain in balance. 130 * What kmap_atomic of a lowmem page does depends on config 131 * and architecture, so pretend to kmap_atomic some lowmem page. 132 */ 133 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 134} 135 136static inline void shmem_swp_unmap(swp_entry_t *entry) 137{ 138 kunmap_atomic(entry, KM_USER1); 139} 140 141static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 142{ 143 return sb->s_fs_info; 144} 145 146/* 147 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 148 * for shared memory and for shared anonymous (/dev/zero) mappings 149 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 150 * consistent with the pre-accounting of private mappings ... 151 */ 152static inline int shmem_acct_size(unsigned long flags, loff_t size) 153{ 154 return (flags & VM_ACCOUNT)? 155 security_vm_enough_memory(VM_ACCT(size)): 0; 156} 157 158static inline void shmem_unacct_size(unsigned long flags, loff_t size) 159{ 160 if (flags & VM_ACCOUNT) 161 vm_unacct_memory(VM_ACCT(size)); 162} 163 164/* 165 * ... whereas tmpfs objects are accounted incrementally as 166 * pages are allocated, in order to allow huge sparse files. 167 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 168 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 169 */ 170static inline int shmem_acct_block(unsigned long flags) 171{ 172 return (flags & VM_ACCOUNT)? 173 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 174} 175 176static inline void shmem_unacct_blocks(unsigned long flags, long pages) 177{ 178 if (!(flags & VM_ACCOUNT)) 179 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 180} 181 182static const struct super_operations shmem_ops; 183static const struct address_space_operations shmem_aops; 184static const struct file_operations shmem_file_operations; 185static const struct inode_operations shmem_inode_operations; 186static const struct inode_operations shmem_dir_inode_operations; 187static const struct inode_operations shmem_special_inode_operations; 188static struct vm_operations_struct shmem_vm_ops; 189 190static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 191 .ra_pages = 0, /* No readahead */ 192 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 193 .unplug_io_fn = default_unplug_io_fn, 194}; 195 196static LIST_HEAD(shmem_swaplist); 197static DEFINE_SPINLOCK(shmem_swaplist_lock); 198 199static void shmem_free_blocks(struct inode *inode, long pages) 200{ 201 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 202 if (sbinfo->max_blocks) { 203 spin_lock(&sbinfo->stat_lock); 204 sbinfo->free_blocks += pages; 205 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 206 spin_unlock(&sbinfo->stat_lock); 207 } 208} 209 210/* 211 * shmem_recalc_inode - recalculate the size of an inode 212 * 213 * @inode: inode to recalc 214 * 215 * We have to calculate the free blocks since the mm can drop 216 * undirtied hole pages behind our back. 217 * 218 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 219 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 220 * 221 * It has to be called with the spinlock held. 222 */ 223static void shmem_recalc_inode(struct inode *inode) 224{ 225 struct shmem_inode_info *info = SHMEM_I(inode); 226 long freed; 227 228 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 229 if (freed > 0) { 230 info->alloced -= freed; 231 shmem_unacct_blocks(info->flags, freed); 232 shmem_free_blocks(inode, freed); 233 } 234} 235 236/* 237 * shmem_swp_entry - find the swap vector position in the info structure 238 * 239 * @info: info structure for the inode 240 * @index: index of the page to find 241 * @page: optional page to add to the structure. Has to be preset to 242 * all zeros 243 * 244 * If there is no space allocated yet it will return NULL when 245 * page is NULL, else it will use the page for the needed block, 246 * setting it to NULL on return to indicate that it has been used. 247 * 248 * The swap vector is organized the following way: 249 * 250 * There are SHMEM_NR_DIRECT entries directly stored in the 251 * shmem_inode_info structure. So small files do not need an addional 252 * allocation. 253 * 254 * For pages with index > SHMEM_NR_DIRECT there is the pointer 255 * i_indirect which points to a page which holds in the first half 256 * doubly indirect blocks, in the second half triple indirect blocks: 257 * 258 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 259 * following layout (for SHMEM_NR_DIRECT == 16): 260 * 261 * i_indirect -> dir --> 16-19 262 * | +-> 20-23 263 * | 264 * +-->dir2 --> 24-27 265 * | +-> 28-31 266 * | +-> 32-35 267 * | +-> 36-39 268 * | 269 * +-->dir3 --> 40-43 270 * +-> 44-47 271 * +-> 48-51 272 * +-> 52-55 273 */ 274static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 275{ 276 unsigned long offset; 277 struct page **dir; 278 struct page *subdir; 279 280 if (index < SHMEM_NR_DIRECT) { 281 shmem_swp_balance_unmap(); 282 return info->i_direct+index; 283 } 284 if (!info->i_indirect) { 285 if (page) { 286 info->i_indirect = *page; 287 *page = NULL; 288 } 289 return NULL; /* need another page */ 290 } 291 292 index -= SHMEM_NR_DIRECT; 293 offset = index % ENTRIES_PER_PAGE; 294 index /= ENTRIES_PER_PAGE; 295 dir = shmem_dir_map(info->i_indirect); 296 297 if (index >= ENTRIES_PER_PAGE/2) { 298 index -= ENTRIES_PER_PAGE/2; 299 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 300 index %= ENTRIES_PER_PAGE; 301 subdir = *dir; 302 if (!subdir) { 303 if (page) { 304 *dir = *page; 305 *page = NULL; 306 } 307 shmem_dir_unmap(dir); 308 return NULL; /* need another page */ 309 } 310 shmem_dir_unmap(dir); 311 dir = shmem_dir_map(subdir); 312 } 313 314 dir += index; 315 subdir = *dir; 316 if (!subdir) { 317 if (!page || !(subdir = *page)) { 318 shmem_dir_unmap(dir); 319 return NULL; /* need a page */ 320 } 321 *dir = subdir; 322 *page = NULL; 323 } 324 shmem_dir_unmap(dir); 325 return shmem_swp_map(subdir) + offset; 326} 327 328static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 329{ 330 long incdec = value? 1: -1; 331 332 entry->val = value; 333 info->swapped += incdec; 334 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 335 struct page *page = kmap_atomic_to_page(entry); 336 set_page_private(page, page_private(page) + incdec); 337 } 338} 339 340/* 341 * shmem_swp_alloc - get the position of the swap entry for the page. 342 * If it does not exist allocate the entry. 343 * 344 * @info: info structure for the inode 345 * @index: index of the page to find 346 * @sgp: check and recheck i_size? skip allocation? 347 */ 348static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 349{ 350 struct inode *inode = &info->vfs_inode; 351 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 352 struct page *page = NULL; 353 swp_entry_t *entry; 354 355 if (sgp != SGP_WRITE && 356 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 357 return ERR_PTR(-EINVAL); 358 359 while (!(entry = shmem_swp_entry(info, index, &page))) { 360 if (sgp == SGP_READ) 361 return shmem_swp_map(ZERO_PAGE(0)); 362 /* 363 * Test free_blocks against 1 not 0, since we have 1 data 364 * page (and perhaps indirect index pages) yet to allocate: 365 * a waste to allocate index if we cannot allocate data. 366 */ 367 if (sbinfo->max_blocks) { 368 spin_lock(&sbinfo->stat_lock); 369 if (sbinfo->free_blocks <= 1) { 370 spin_unlock(&sbinfo->stat_lock); 371 return ERR_PTR(-ENOSPC); 372 } 373 sbinfo->free_blocks--; 374 inode->i_blocks += BLOCKS_PER_PAGE; 375 spin_unlock(&sbinfo->stat_lock); 376 } 377 378 spin_unlock(&info->lock); 379 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); 380 if (page) 381 set_page_private(page, 0); 382 spin_lock(&info->lock); 383 384 if (!page) { 385 shmem_free_blocks(inode, 1); 386 return ERR_PTR(-ENOMEM); 387 } 388 if (sgp != SGP_WRITE && 389 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 390 entry = ERR_PTR(-EINVAL); 391 break; 392 } 393 if (info->next_index <= index) 394 info->next_index = index + 1; 395 } 396 if (page) { 397 /* another task gave its page, or truncated the file */ 398 shmem_free_blocks(inode, 1); 399 shmem_dir_free(page); 400 } 401 if (info->next_index <= index && !IS_ERR(entry)) 402 info->next_index = index + 1; 403 return entry; 404} 405 406/* 407 * shmem_free_swp - free some swap entries in a directory 408 * 409 * @dir: pointer to the directory 410 * @edir: pointer after last entry of the directory 411 * @punch_lock: pointer to spinlock when needed for the holepunch case 412 */ 413static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, 414 spinlock_t *punch_lock) 415{ 416 spinlock_t *punch_unlock = NULL; 417 swp_entry_t *ptr; 418 int freed = 0; 419 420 for (ptr = dir; ptr < edir; ptr++) { 421 if (ptr->val) { 422 if (unlikely(punch_lock)) { 423 punch_unlock = punch_lock; 424 punch_lock = NULL; 425 spin_lock(punch_unlock); 426 if (!ptr->val) 427 continue; 428 } 429 free_swap_and_cache(*ptr); 430 *ptr = (swp_entry_t){0}; 431 freed++; 432 } 433 } 434 if (punch_unlock) 435 spin_unlock(punch_unlock); 436 return freed; 437} 438 439static int shmem_map_and_free_swp(struct page *subdir, int offset, 440 int limit, struct page ***dir, spinlock_t *punch_lock) 441{ 442 swp_entry_t *ptr; 443 int freed = 0; 444 445 ptr = shmem_swp_map(subdir); 446 for (; offset < limit; offset += LATENCY_LIMIT) { 447 int size = limit - offset; 448 if (size > LATENCY_LIMIT) 449 size = LATENCY_LIMIT; 450 freed += shmem_free_swp(ptr+offset, ptr+offset+size, 451 punch_lock); 452 if (need_resched()) { 453 shmem_swp_unmap(ptr); 454 if (*dir) { 455 shmem_dir_unmap(*dir); 456 *dir = NULL; 457 } 458 cond_resched(); 459 ptr = shmem_swp_map(subdir); 460 } 461 } 462 shmem_swp_unmap(ptr); 463 return freed; 464} 465 466static void shmem_free_pages(struct list_head *next) 467{ 468 struct page *page; 469 int freed = 0; 470 471 do { 472 page = container_of(next, struct page, lru); 473 next = next->next; 474 shmem_dir_free(page); 475 freed++; 476 if (freed >= LATENCY_LIMIT) { 477 cond_resched(); 478 freed = 0; 479 } 480 } while (next); 481} 482 483static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 484{ 485 struct shmem_inode_info *info = SHMEM_I(inode); 486 unsigned long idx; 487 unsigned long size; 488 unsigned long limit; 489 unsigned long stage; 490 unsigned long diroff; 491 struct page **dir; 492 struct page *topdir; 493 struct page *middir; 494 struct page *subdir; 495 swp_entry_t *ptr; 496 LIST_HEAD(pages_to_free); 497 long nr_pages_to_free = 0; 498 long nr_swaps_freed = 0; 499 int offset; 500 int freed; 501 int punch_hole; 502 spinlock_t *needs_lock; 503 spinlock_t *punch_lock; 504 unsigned long upper_limit; 505 506 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 507 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 508 if (idx >= info->next_index) 509 return; 510 511 spin_lock(&info->lock); 512 info->flags |= SHMEM_TRUNCATE; 513 if (likely(end == (loff_t) -1)) { 514 limit = info->next_index; 515 upper_limit = SHMEM_MAX_INDEX; 516 info->next_index = idx; 517 needs_lock = NULL; 518 punch_hole = 0; 519 } else { 520 if (end + 1 >= inode->i_size) { /* we may free a little more */ 521 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> 522 PAGE_CACHE_SHIFT; 523 upper_limit = SHMEM_MAX_INDEX; 524 } else { 525 limit = (end + 1) >> PAGE_CACHE_SHIFT; 526 upper_limit = limit; 527 } 528 needs_lock = &info->lock; 529 punch_hole = 1; 530 } 531 532 topdir = info->i_indirect; 533 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 534 info->i_indirect = NULL; 535 nr_pages_to_free++; 536 list_add(&topdir->lru, &pages_to_free); 537 } 538 spin_unlock(&info->lock); 539 540 if (info->swapped && idx < SHMEM_NR_DIRECT) { 541 ptr = info->i_direct; 542 size = limit; 543 if (size > SHMEM_NR_DIRECT) 544 size = SHMEM_NR_DIRECT; 545 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); 546 } 547 548 /* 549 * If there are no indirect blocks or we are punching a hole 550 * below indirect blocks, nothing to be done. 551 */ 552 if (!topdir || limit <= SHMEM_NR_DIRECT) 553 goto done2; 554 555 /* 556 * The truncation case has already dropped info->lock, and we're safe 557 * because i_size and next_index have already been lowered, preventing 558 * access beyond. But in the punch_hole case, we still need to take 559 * the lock when updating the swap directory, because there might be 560 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or 561 * shmem_writepage. However, whenever we find we can remove a whole 562 * directory page (not at the misaligned start or end of the range), 563 * we first NULLify its pointer in the level above, and then have no 564 * need to take the lock when updating its contents: needs_lock and 565 * punch_lock (either pointing to info->lock or NULL) manage this. 566 */ 567 568 upper_limit -= SHMEM_NR_DIRECT; 569 limit -= SHMEM_NR_DIRECT; 570 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 571 offset = idx % ENTRIES_PER_PAGE; 572 idx -= offset; 573 574 dir = shmem_dir_map(topdir); 575 stage = ENTRIES_PER_PAGEPAGE/2; 576 if (idx < ENTRIES_PER_PAGEPAGE/2) { 577 middir = topdir; 578 diroff = idx/ENTRIES_PER_PAGE; 579 } else { 580 dir += ENTRIES_PER_PAGE/2; 581 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 582 while (stage <= idx) 583 stage += ENTRIES_PER_PAGEPAGE; 584 middir = *dir; 585 if (*dir) { 586 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 587 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 588 if (!diroff && !offset && upper_limit >= stage) { 589 if (needs_lock) { 590 spin_lock(needs_lock); 591 *dir = NULL; 592 spin_unlock(needs_lock); 593 needs_lock = NULL; 594 } else 595 *dir = NULL; 596 nr_pages_to_free++; 597 list_add(&middir->lru, &pages_to_free); 598 } 599 shmem_dir_unmap(dir); 600 dir = shmem_dir_map(middir); 601 } else { 602 diroff = 0; 603 offset = 0; 604 idx = stage; 605 } 606 } 607 608 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 609 if (unlikely(idx == stage)) { 610 shmem_dir_unmap(dir); 611 dir = shmem_dir_map(topdir) + 612 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 613 while (!*dir) { 614 dir++; 615 idx += ENTRIES_PER_PAGEPAGE; 616 if (idx >= limit) 617 goto done1; 618 } 619 stage = idx + ENTRIES_PER_PAGEPAGE; 620 middir = *dir; 621 if (punch_hole) 622 needs_lock = &info->lock; 623 if (upper_limit >= stage) { 624 if (needs_lock) { 625 spin_lock(needs_lock); 626 *dir = NULL; 627 spin_unlock(needs_lock); 628 needs_lock = NULL; 629 } else 630 *dir = NULL; 631 nr_pages_to_free++; 632 list_add(&middir->lru, &pages_to_free); 633 } 634 shmem_dir_unmap(dir); 635 cond_resched(); 636 dir = shmem_dir_map(middir); 637 diroff = 0; 638 } 639 punch_lock = needs_lock; 640 subdir = dir[diroff]; 641 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { 642 if (needs_lock) { 643 spin_lock(needs_lock); 644 dir[diroff] = NULL; 645 spin_unlock(needs_lock); 646 punch_lock = NULL; 647 } else 648 dir[diroff] = NULL; 649 nr_pages_to_free++; 650 list_add(&subdir->lru, &pages_to_free); 651 } 652 if (subdir && page_private(subdir) /* has swap entries */) { 653 size = limit - idx; 654 if (size > ENTRIES_PER_PAGE) 655 size = ENTRIES_PER_PAGE; 656 freed = shmem_map_and_free_swp(subdir, 657 offset, size, &dir, punch_lock); 658 if (!dir) 659 dir = shmem_dir_map(middir); 660 nr_swaps_freed += freed; 661 if (offset || punch_lock) { 662 spin_lock(&info->lock); 663 set_page_private(subdir, 664 page_private(subdir) - freed); 665 spin_unlock(&info->lock); 666 } else 667 BUG_ON(page_private(subdir) != freed); 668 } 669 offset = 0; 670 } 671done1: 672 shmem_dir_unmap(dir); 673done2: 674 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 675 /* 676 * Call truncate_inode_pages again: racing shmem_unuse_inode 677 * may have swizzled a page in from swap since vmtruncate or 678 * generic_delete_inode did it, before we lowered next_index. 679 * Also, though shmem_getpage checks i_size before adding to 680 * cache, no recheck after: so fix the narrow window there too. 681 * 682 * Recalling truncate_inode_pages_range and unmap_mapping_range 683 * every time for punch_hole (which never got a chance to clear 684 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 685 * yet hardly ever necessary: try to optimize them out later. 686 */ 687 truncate_inode_pages_range(inode->i_mapping, start, end); 688 if (punch_hole) 689 unmap_mapping_range(inode->i_mapping, start, 690 end - start, 1); 691 } 692 693 spin_lock(&info->lock); 694 info->flags &= ~SHMEM_TRUNCATE; 695 info->swapped -= nr_swaps_freed; 696 if (nr_pages_to_free) 697 shmem_free_blocks(inode, nr_pages_to_free); 698 shmem_recalc_inode(inode); 699 spin_unlock(&info->lock); 700 701 /* 702 * Empty swap vector directory pages to be freed? 703 */ 704 if (!list_empty(&pages_to_free)) { 705 pages_to_free.prev->next = NULL; 706 shmem_free_pages(pages_to_free.next); 707 } 708} 709 710static void shmem_truncate(struct inode *inode) 711{ 712 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 713} 714 715static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 716{ 717 struct inode *inode = dentry->d_inode; 718 struct page *page = NULL; 719 int error; 720 721 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 722 if (attr->ia_size < inode->i_size) { 723 /* 724 * If truncating down to a partial page, then 725 * if that page is already allocated, hold it 726 * in memory until the truncation is over, so 727 * truncate_partial_page cannnot miss it were 728 * it assigned to swap. 729 */ 730 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 731 (void) shmem_getpage(inode, 732 attr->ia_size>>PAGE_CACHE_SHIFT, 733 &page, SGP_READ, NULL); 734 } 735 /* 736 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 737 * detect if any pages might have been added to cache 738 * after truncate_inode_pages. But we needn't bother 739 * if it's being fully truncated to zero-length: the 740 * nrpages check is efficient enough in that case. 741 */ 742 if (attr->ia_size) { 743 struct shmem_inode_info *info = SHMEM_I(inode); 744 spin_lock(&info->lock); 745 info->flags &= ~SHMEM_PAGEIN; 746 spin_unlock(&info->lock); 747 } 748 } 749 } 750 751 error = inode_change_ok(inode, attr); 752 if (!error) 753 error = inode_setattr(inode, attr); 754#ifdef CONFIG_TMPFS_POSIX_ACL 755 if (!error && (attr->ia_valid & ATTR_MODE)) 756 error = generic_acl_chmod(inode, &shmem_acl_ops); 757#endif 758 if (page) 759 page_cache_release(page); 760 return error; 761} 762 763static void shmem_delete_inode(struct inode *inode) 764{ 765 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 766 struct shmem_inode_info *info = SHMEM_I(inode); 767 768 if (inode->i_op->truncate == shmem_truncate) { 769 truncate_inode_pages(inode->i_mapping, 0); 770 shmem_unacct_size(info->flags, inode->i_size); 771 inode->i_size = 0; 772 shmem_truncate(inode); 773 if (!list_empty(&info->swaplist)) { 774 spin_lock(&shmem_swaplist_lock); 775 list_del_init(&info->swaplist); 776 spin_unlock(&shmem_swaplist_lock); 777 } 778 } 779 BUG_ON(inode->i_blocks); 780 if (sbinfo->max_inodes) { 781 spin_lock(&sbinfo->stat_lock); 782 sbinfo->free_inodes++; 783 spin_unlock(&sbinfo->stat_lock); 784 } 785 clear_inode(inode); 786} 787 788static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 789{ 790 swp_entry_t *ptr; 791 792 for (ptr = dir; ptr < edir; ptr++) { 793 if (ptr->val == entry.val) 794 return ptr - dir; 795 } 796 return -1; 797} 798 799static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 800{ 801 struct inode *inode; 802 unsigned long idx; 803 unsigned long size; 804 unsigned long limit; 805 unsigned long stage; 806 struct page **dir; 807 struct page *subdir; 808 swp_entry_t *ptr; 809 int offset; 810 811 idx = 0; 812 ptr = info->i_direct; 813 spin_lock(&info->lock); 814 limit = info->next_index; 815 size = limit; 816 if (size > SHMEM_NR_DIRECT) 817 size = SHMEM_NR_DIRECT; 818 offset = shmem_find_swp(entry, ptr, ptr+size); 819 if (offset >= 0) { 820 shmem_swp_balance_unmap(); 821 goto found; 822 } 823 if (!info->i_indirect) 824 goto lost2; 825 826 dir = shmem_dir_map(info->i_indirect); 827 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 828 829 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 830 if (unlikely(idx == stage)) { 831 shmem_dir_unmap(dir-1); 832 dir = shmem_dir_map(info->i_indirect) + 833 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 834 while (!*dir) { 835 dir++; 836 idx += ENTRIES_PER_PAGEPAGE; 837 if (idx >= limit) 838 goto lost1; 839 } 840 stage = idx + ENTRIES_PER_PAGEPAGE; 841 subdir = *dir; 842 shmem_dir_unmap(dir); 843 dir = shmem_dir_map(subdir); 844 } 845 subdir = *dir; 846 if (subdir && page_private(subdir)) { 847 ptr = shmem_swp_map(subdir); 848 size = limit - idx; 849 if (size > ENTRIES_PER_PAGE) 850 size = ENTRIES_PER_PAGE; 851 offset = shmem_find_swp(entry, ptr, ptr+size); 852 if (offset >= 0) { 853 shmem_dir_unmap(dir); 854 goto found; 855 } 856 shmem_swp_unmap(ptr); 857 } 858 } 859lost1: 860 shmem_dir_unmap(dir-1); 861lost2: 862 spin_unlock(&info->lock); 863 return 0; 864found: 865 idx += offset; 866 inode = &info->vfs_inode; 867 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 868 info->flags |= SHMEM_PAGEIN; 869 shmem_swp_set(info, ptr + offset, 0); 870 } 871 shmem_swp_unmap(ptr); 872 spin_unlock(&info->lock); 873 /* 874 * Decrement swap count even when the entry is left behind: 875 * try_to_unuse will skip over mms, then reincrement count. 876 */ 877 swap_free(entry); 878 return 1; 879} 880 881/* 882 * shmem_unuse() search for an eventually swapped out shmem page. 883 */ 884int shmem_unuse(swp_entry_t entry, struct page *page) 885{ 886 struct list_head *p, *next; 887 struct shmem_inode_info *info; 888 int found = 0; 889 890 spin_lock(&shmem_swaplist_lock); 891 list_for_each_safe(p, next, &shmem_swaplist) { 892 info = list_entry(p, struct shmem_inode_info, swaplist); 893 if (!info->swapped) 894 list_del_init(&info->swaplist); 895 else if (shmem_unuse_inode(info, entry, page)) { 896 /* move head to start search for next from here */ 897 list_move_tail(&shmem_swaplist, &info->swaplist); 898 found = 1; 899 break; 900 } 901 } 902 spin_unlock(&shmem_swaplist_lock); 903 return found; 904} 905 906/* 907 * Move the page from the page cache to the swap cache. 908 */ 909static int shmem_writepage(struct page *page, struct writeback_control *wbc) 910{ 911 struct shmem_inode_info *info; 912 swp_entry_t *entry, swap; 913 struct address_space *mapping; 914 unsigned long index; 915 struct inode *inode; 916 917 BUG_ON(!PageLocked(page)); 918 /* 919 * shmem_backing_dev_info's capabilities prevent regular writeback or 920 * sync from ever calling shmem_writepage; but a stacking filesystem 921 * may use the ->writepage of its underlying filesystem, in which case 922 * we want to do nothing when that underlying filesystem is tmpfs 923 * (writing out to swap is useful as a response to memory pressure, but 924 * of no use to stabilize the data) - just redirty the page, unlock it 925 * and claim success in this case. AOP_WRITEPAGE_ACTIVATE, and the 926 * page_mapped check below, must be avoided unless we're in reclaim. 927 */ 928 if (!wbc->for_reclaim) { 929 set_page_dirty(page); 930 unlock_page(page); 931 return 0; 932 } 933 BUG_ON(page_mapped(page)); 934 935 mapping = page->mapping; 936 index = page->index; 937 inode = mapping->host; 938 info = SHMEM_I(inode); 939 if (info->flags & VM_LOCKED) 940 goto redirty; 941 swap = get_swap_page(); 942 if (!swap.val) 943 goto redirty; 944 945 spin_lock(&info->lock); 946 shmem_recalc_inode(inode); 947 if (index >= info->next_index) { 948 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 949 goto unlock; 950 } 951 entry = shmem_swp_entry(info, index, NULL); 952 BUG_ON(!entry); 953 BUG_ON(entry->val); 954 955 if (move_to_swap_cache(page, swap) == 0) { 956 shmem_swp_set(info, entry, swap.val); 957 shmem_swp_unmap(entry); 958 spin_unlock(&info->lock); 959 if (list_empty(&info->swaplist)) { 960 spin_lock(&shmem_swaplist_lock); 961 /* move instead of add in case we're racing */ 962 list_move_tail(&info->swaplist, &shmem_swaplist); 963 spin_unlock(&shmem_swaplist_lock); 964 } 965 unlock_page(page); 966 return 0; 967 } 968 969 shmem_swp_unmap(entry); 970unlock: 971 spin_unlock(&info->lock); 972 swap_free(swap); 973redirty: 974 set_page_dirty(page); 975 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ 976} 977 978#ifdef CONFIG_NUMA 979static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 980{ 981 char *nodelist = strchr(value, ':'); 982 int err = 1; 983 984 if (nodelist) { 985 /* NUL-terminate policy string */ 986 *nodelist++ = '\0'; 987 if (nodelist_parse(nodelist, *policy_nodes)) 988 goto out; 989 if (!nodes_subset(*policy_nodes, node_states[N_HIGH_MEMORY])) 990 goto out; 991 } 992 if (!strcmp(value, "default")) { 993 *policy = MPOL_DEFAULT; 994 /* Don't allow a nodelist */ 995 if (!nodelist) 996 err = 0; 997 } else if (!strcmp(value, "prefer")) { 998 *policy = MPOL_PREFERRED; 999 /* Insist on a nodelist of one node only */ 1000 if (nodelist) { 1001 char *rest = nodelist; 1002 while (isdigit(*rest)) 1003 rest++; 1004 if (!*rest) 1005 err = 0; 1006 } 1007 } else if (!strcmp(value, "bind")) { 1008 *policy = MPOL_BIND; 1009 /* Insist on a nodelist */ 1010 if (nodelist) 1011 err = 0; 1012 } else if (!strcmp(value, "interleave")) { 1013 *policy = MPOL_INTERLEAVE; 1014 /* 1015 * Default to online nodes with memory if no nodelist 1016 */ 1017 if (!nodelist) 1018 *policy_nodes = node_states[N_HIGH_MEMORY]; 1019 err = 0; 1020 } 1021out: 1022 /* Restore string for error message */ 1023 if (nodelist) 1024 *--nodelist = ':'; 1025 return err; 1026} 1027 1028static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1029 struct shmem_inode_info *info, unsigned long idx) 1030{ 1031 struct vm_area_struct pvma; 1032 struct page *page; 1033 1034 /* Create a pseudo vma that just contains the policy */ 1035 pvma.vm_start = 0; 1036 pvma.vm_pgoff = idx; 1037 pvma.vm_ops = NULL; 1038 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1039 page = swapin_readahead(entry, gfp, &pvma, 0); 1040 mpol_free(pvma.vm_policy); 1041 return page; 1042} 1043 1044static struct page *shmem_alloc_page(gfp_t gfp, 1045 struct shmem_inode_info *info, unsigned long idx) 1046{ 1047 struct vm_area_struct pvma; 1048 struct page *page; 1049 1050 /* Create a pseudo vma that just contains the policy */ 1051 pvma.vm_start = 0; 1052 pvma.vm_pgoff = idx; 1053 pvma.vm_ops = NULL; 1054 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1055 page = alloc_page_vma(gfp, &pvma, 0); 1056 mpol_free(pvma.vm_policy); 1057 return page; 1058} 1059#else 1060static inline int shmem_parse_mpol(char *value, int *policy, 1061 nodemask_t *policy_nodes) 1062{ 1063 return 1; 1064} 1065 1066static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1067 struct shmem_inode_info *info, unsigned long idx) 1068{ 1069 return swapin_readahead(entry, gfp, NULL, 0); 1070} 1071 1072static inline struct page *shmem_alloc_page(gfp_t gfp, 1073 struct shmem_inode_info *info, unsigned long idx) 1074{ 1075 return alloc_page(gfp); 1076} 1077#endif 1078 1079/* 1080 * shmem_getpage - either get the page from swap or allocate a new one 1081 * 1082 * If we allocate a new one we do not mark it dirty. That's up to the 1083 * vm. If we swap it in we mark it dirty since we also free the swap 1084 * entry since a page cannot live in both the swap and page cache 1085 */ 1086static int shmem_getpage(struct inode *inode, unsigned long idx, 1087 struct page **pagep, enum sgp_type sgp, int *type) 1088{ 1089 struct address_space *mapping = inode->i_mapping; 1090 struct shmem_inode_info *info = SHMEM_I(inode); 1091 struct shmem_sb_info *sbinfo; 1092 struct page *filepage = *pagep; 1093 struct page *swappage; 1094 swp_entry_t *entry; 1095 swp_entry_t swap; 1096 gfp_t gfp; 1097 int error; 1098 1099 if (idx >= SHMEM_MAX_INDEX) 1100 return -EFBIG; 1101 1102 if (type) 1103 *type = 0; 1104 1105 /* 1106 * Normally, filepage is NULL on entry, and either found 1107 * uptodate immediately, or allocated and zeroed, or read 1108 * in under swappage, which is then assigned to filepage. 1109 * But shmem_readpage and shmem_write_begin pass in a locked 1110 * filepage, which may be found not uptodate by other callers 1111 * too, and may need to be copied from the swappage read in. 1112 */ 1113repeat: 1114 if (!filepage) 1115 filepage = find_lock_page(mapping, idx); 1116 if (filepage && PageUptodate(filepage)) 1117 goto done; 1118 error = 0; 1119 if (sgp == SGP_QUICK) 1120 goto failed; 1121 gfp = mapping_gfp_mask(mapping); 1122 1123 spin_lock(&info->lock); 1124 shmem_recalc_inode(inode); 1125 entry = shmem_swp_alloc(info, idx, sgp); 1126 if (IS_ERR(entry)) { 1127 spin_unlock(&info->lock); 1128 error = PTR_ERR(entry); 1129 goto failed; 1130 } 1131 swap = *entry; 1132 1133 if (swap.val) { 1134 /* Look it up and read it in.. */ 1135 swappage = lookup_swap_cache(swap); 1136 if (!swappage) { 1137 shmem_swp_unmap(entry); 1138 /* here we actually do the io */ 1139 if (type && !(*type & VM_FAULT_MAJOR)) { 1140 __count_vm_event(PGMAJFAULT); 1141 *type |= VM_FAULT_MAJOR; 1142 } 1143 spin_unlock(&info->lock); 1144 swappage = shmem_swapin(swap, gfp, info, idx); 1145 if (!swappage) { 1146 spin_lock(&info->lock); 1147 entry = shmem_swp_alloc(info, idx, sgp); 1148 if (IS_ERR(entry)) 1149 error = PTR_ERR(entry); 1150 else { 1151 if (entry->val == swap.val) 1152 error = -ENOMEM; 1153 shmem_swp_unmap(entry); 1154 } 1155 spin_unlock(&info->lock); 1156 if (error) 1157 goto failed; 1158 goto repeat; 1159 } 1160 wait_on_page_locked(swappage); 1161 page_cache_release(swappage); 1162 goto repeat; 1163 } 1164 1165 /* We have to do this with page locked to prevent races */ 1166 if (TestSetPageLocked(swappage)) { 1167 shmem_swp_unmap(entry); 1168 spin_unlock(&info->lock); 1169 wait_on_page_locked(swappage); 1170 page_cache_release(swappage); 1171 goto repeat; 1172 } 1173 if (PageWriteback(swappage)) { 1174 shmem_swp_unmap(entry); 1175 spin_unlock(&info->lock); 1176 wait_on_page_writeback(swappage); 1177 unlock_page(swappage); 1178 page_cache_release(swappage); 1179 goto repeat; 1180 } 1181 if (!PageUptodate(swappage)) { 1182 shmem_swp_unmap(entry); 1183 spin_unlock(&info->lock); 1184 unlock_page(swappage); 1185 page_cache_release(swappage); 1186 error = -EIO; 1187 goto failed; 1188 } 1189 1190 if (filepage) { 1191 shmem_swp_set(info, entry, 0); 1192 shmem_swp_unmap(entry); 1193 delete_from_swap_cache(swappage); 1194 spin_unlock(&info->lock); 1195 copy_highpage(filepage, swappage); 1196 unlock_page(swappage); 1197 page_cache_release(swappage); 1198 flush_dcache_page(filepage); 1199 SetPageUptodate(filepage); 1200 set_page_dirty(filepage); 1201 swap_free(swap); 1202 } else if (!(error = move_from_swap_cache( 1203 swappage, idx, mapping))) { 1204 info->flags |= SHMEM_PAGEIN; 1205 shmem_swp_set(info, entry, 0); 1206 shmem_swp_unmap(entry); 1207 spin_unlock(&info->lock); 1208 filepage = swappage; 1209 swap_free(swap); 1210 } else { 1211 shmem_swp_unmap(entry); 1212 spin_unlock(&info->lock); 1213 unlock_page(swappage); 1214 page_cache_release(swappage); 1215 if (error == -ENOMEM) { 1216 /* let kswapd refresh zone for GFP_ATOMICs */ 1217 congestion_wait(WRITE, HZ/50); 1218 } 1219 goto repeat; 1220 } 1221 } else if (sgp == SGP_READ && !filepage) { 1222 shmem_swp_unmap(entry); 1223 filepage = find_get_page(mapping, idx); 1224 if (filepage && 1225 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1226 spin_unlock(&info->lock); 1227 wait_on_page_locked(filepage); 1228 page_cache_release(filepage); 1229 filepage = NULL; 1230 goto repeat; 1231 } 1232 spin_unlock(&info->lock); 1233 } else { 1234 shmem_swp_unmap(entry); 1235 sbinfo = SHMEM_SB(inode->i_sb); 1236 if (sbinfo->max_blocks) { 1237 spin_lock(&sbinfo->stat_lock); 1238 if (sbinfo->free_blocks == 0 || 1239 shmem_acct_block(info->flags)) { 1240 spin_unlock(&sbinfo->stat_lock); 1241 spin_unlock(&info->lock); 1242 error = -ENOSPC; 1243 goto failed; 1244 } 1245 sbinfo->free_blocks--; 1246 inode->i_blocks += BLOCKS_PER_PAGE; 1247 spin_unlock(&sbinfo->stat_lock); 1248 } else if (shmem_acct_block(info->flags)) { 1249 spin_unlock(&info->lock); 1250 error = -ENOSPC; 1251 goto failed; 1252 } 1253 1254 if (!filepage) { 1255 spin_unlock(&info->lock); 1256 filepage = shmem_alloc_page(gfp, info, idx); 1257 if (!filepage) { 1258 shmem_unacct_blocks(info->flags, 1); 1259 shmem_free_blocks(inode, 1); 1260 error = -ENOMEM; 1261 goto failed; 1262 } 1263 1264 spin_lock(&info->lock); 1265 entry = shmem_swp_alloc(info, idx, sgp); 1266 if (IS_ERR(entry)) 1267 error = PTR_ERR(entry); 1268 else { 1269 swap = *entry; 1270 shmem_swp_unmap(entry); 1271 } 1272 if (error || swap.val || 0 != add_to_page_cache_lru( 1273 filepage, mapping, idx, GFP_ATOMIC)) { 1274 spin_unlock(&info->lock); 1275 page_cache_release(filepage); 1276 shmem_unacct_blocks(info->flags, 1); 1277 shmem_free_blocks(inode, 1); 1278 filepage = NULL; 1279 if (error) 1280 goto failed; 1281 goto repeat; 1282 } 1283 info->flags |= SHMEM_PAGEIN; 1284 } 1285 1286 info->alloced++; 1287 spin_unlock(&info->lock); 1288 clear_highpage(filepage); 1289 flush_dcache_page(filepage); 1290 SetPageUptodate(filepage); 1291 } 1292done: 1293 if (*pagep != filepage) { 1294 *pagep = filepage; 1295 if (sgp != SGP_FAULT) 1296 unlock_page(filepage); 1297 1298 } 1299 return 0; 1300 1301failed: 1302 if (*pagep != filepage) { 1303 unlock_page(filepage); 1304 page_cache_release(filepage); 1305 } 1306 return error; 1307} 1308 1309static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1310{ 1311 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1312 int error; 1313 int ret; 1314 1315 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1316 return VM_FAULT_SIGBUS; 1317 1318 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_FAULT, &ret); 1319 if (error) 1320 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1321 1322 mark_page_accessed(vmf->page); 1323 return ret | VM_FAULT_LOCKED; 1324} 1325 1326#ifdef CONFIG_NUMA 1327static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1328{ 1329 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1330 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1331} 1332 1333static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1334 unsigned long addr) 1335{ 1336 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1337 unsigned long idx; 1338 1339 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1340 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1341} 1342#endif 1343 1344int shmem_lock(struct file *file, int lock, struct user_struct *user) 1345{ 1346 struct inode *inode = file->f_path.dentry->d_inode; 1347 struct shmem_inode_info *info = SHMEM_I(inode); 1348 int retval = -ENOMEM; 1349 1350 spin_lock(&info->lock); 1351 if (lock && !(info->flags & VM_LOCKED)) { 1352 if (!user_shm_lock(inode->i_size, user)) 1353 goto out_nomem; 1354 info->flags |= VM_LOCKED; 1355 } 1356 if (!lock && (info->flags & VM_LOCKED) && user) { 1357 user_shm_unlock(inode->i_size, user); 1358 info->flags &= ~VM_LOCKED; 1359 } 1360 retval = 0; 1361out_nomem: 1362 spin_unlock(&info->lock); 1363 return retval; 1364} 1365 1366static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1367{ 1368 file_accessed(file); 1369 vma->vm_ops = &shmem_vm_ops; 1370 vma->vm_flags |= VM_CAN_NONLINEAR; 1371 return 0; 1372} 1373 1374static struct inode * 1375shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1376{ 1377 struct inode *inode; 1378 struct shmem_inode_info *info; 1379 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1380 1381 if (sbinfo->max_inodes) { 1382 spin_lock(&sbinfo->stat_lock); 1383 if (!sbinfo->free_inodes) { 1384 spin_unlock(&sbinfo->stat_lock); 1385 return NULL; 1386 } 1387 sbinfo->free_inodes--; 1388 spin_unlock(&sbinfo->stat_lock); 1389 } 1390 1391 inode = new_inode(sb); 1392 if (inode) { 1393 inode->i_mode = mode; 1394 inode->i_uid = current->fsuid; 1395 inode->i_gid = current->fsgid; 1396 inode->i_blocks = 0; 1397 inode->i_mapping->a_ops = &shmem_aops; 1398 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1399 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1400 inode->i_generation = get_seconds(); 1401 info = SHMEM_I(inode); 1402 memset(info, 0, (char *)inode - (char *)info); 1403 spin_lock_init(&info->lock); 1404 INIT_LIST_HEAD(&info->swaplist); 1405 1406 switch (mode & S_IFMT) { 1407 default: 1408 inode->i_op = &shmem_special_inode_operations; 1409 init_special_inode(inode, mode, dev); 1410 break; 1411 case S_IFREG: 1412 inode->i_op = &shmem_inode_operations; 1413 inode->i_fop = &shmem_file_operations; 1414 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1415 &sbinfo->policy_nodes); 1416 break; 1417 case S_IFDIR: 1418 inc_nlink(inode); 1419 /* Some things misbehave if size == 0 on a directory */ 1420 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1421 inode->i_op = &shmem_dir_inode_operations; 1422 inode->i_fop = &simple_dir_operations; 1423 break; 1424 case S_IFLNK: 1425 /* 1426 * Must not load anything in the rbtree, 1427 * mpol_free_shared_policy will not be called. 1428 */ 1429 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1430 NULL); 1431 break; 1432 } 1433 } else if (sbinfo->max_inodes) { 1434 spin_lock(&sbinfo->stat_lock); 1435 sbinfo->free_inodes++; 1436 spin_unlock(&sbinfo->stat_lock); 1437 } 1438 return inode; 1439} 1440 1441#ifdef CONFIG_TMPFS 1442static const struct inode_operations shmem_symlink_inode_operations; 1443static const struct inode_operations shmem_symlink_inline_operations; 1444 1445/* 1446 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1447 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1448 * below the loop driver, in the generic fashion that many filesystems support. 1449 */ 1450static int shmem_readpage(struct file *file, struct page *page) 1451{ 1452 struct inode *inode = page->mapping->host; 1453 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1454 unlock_page(page); 1455 return error; 1456} 1457 1458static int 1459shmem_write_begin(struct file *file, struct address_space *mapping, 1460 loff_t pos, unsigned len, unsigned flags, 1461 struct page **pagep, void **fsdata) 1462{ 1463 struct inode *inode = mapping->host; 1464 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1465 *pagep = NULL; 1466 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1467} 1468 1469static int 1470shmem_write_end(struct file *file, struct address_space *mapping, 1471 loff_t pos, unsigned len, unsigned copied, 1472 struct page *page, void *fsdata) 1473{ 1474 struct inode *inode = mapping->host; 1475 1476 set_page_dirty(page); 1477 page_cache_release(page); 1478 1479 if (pos+copied > inode->i_size) 1480 i_size_write(inode, pos+copied); 1481 1482 return copied; 1483} 1484 1485static ssize_t 1486shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1487{ 1488 struct inode *inode = file->f_path.dentry->d_inode; 1489 loff_t pos; 1490 unsigned long written; 1491 ssize_t err; 1492 1493 if ((ssize_t) count < 0) 1494 return -EINVAL; 1495 1496 if (!access_ok(VERIFY_READ, buf, count)) 1497 return -EFAULT; 1498 1499 mutex_lock(&inode->i_mutex); 1500 1501 pos = *ppos; 1502 written = 0; 1503 1504 err = generic_write_checks(file, &pos, &count, 0); 1505 if (err || !count) 1506 goto out; 1507 1508 err = remove_suid(file->f_path.dentry); 1509 if (err) 1510 goto out; 1511 1512 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1513 1514 do { 1515 struct page *page = NULL; 1516 unsigned long bytes, index, offset; 1517 char *kaddr; 1518 int left; 1519 1520 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1521 index = pos >> PAGE_CACHE_SHIFT; 1522 bytes = PAGE_CACHE_SIZE - offset; 1523 if (bytes > count) 1524 bytes = count; 1525 1526 /* 1527 * We don't hold page lock across copy from user - 1528 * what would it guard against? - so no deadlock here. 1529 * But it still may be a good idea to prefault below. 1530 */ 1531 1532 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1533 if (err) 1534 break; 1535 1536 left = bytes; 1537 if (PageHighMem(page)) { 1538 volatile unsigned char dummy; 1539 __get_user(dummy, buf); 1540 __get_user(dummy, buf + bytes - 1); 1541 1542 kaddr = kmap_atomic(page, KM_USER0); 1543 left = __copy_from_user_inatomic(kaddr + offset, 1544 buf, bytes); 1545 kunmap_atomic(kaddr, KM_USER0); 1546 } 1547 if (left) { 1548 kaddr = kmap(page); 1549 left = __copy_from_user(kaddr + offset, buf, bytes); 1550 kunmap(page); 1551 } 1552 1553 written += bytes; 1554 count -= bytes; 1555 pos += bytes; 1556 buf += bytes; 1557 if (pos > inode->i_size) 1558 i_size_write(inode, pos); 1559 1560 flush_dcache_page(page); 1561 set_page_dirty(page); 1562 mark_page_accessed(page); 1563 page_cache_release(page); 1564 1565 if (left) { 1566 pos -= left; 1567 written -= left; 1568 err = -EFAULT; 1569 break; 1570 } 1571 1572 /* 1573 * Our dirty pages are not counted in nr_dirty, 1574 * and we do not attempt to balance dirty pages. 1575 */ 1576 1577 cond_resched(); 1578 } while (count); 1579 1580 *ppos = pos; 1581 if (written) 1582 err = written; 1583out: 1584 mutex_unlock(&inode->i_mutex); 1585 return err; 1586} 1587 1588static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1589{ 1590 struct inode *inode = filp->f_path.dentry->d_inode; 1591 struct address_space *mapping = inode->i_mapping; 1592 unsigned long index, offset; 1593 1594 index = *ppos >> PAGE_CACHE_SHIFT; 1595 offset = *ppos & ~PAGE_CACHE_MASK; 1596 1597 for (;;) { 1598 struct page *page = NULL; 1599 unsigned long end_index, nr, ret; 1600 loff_t i_size = i_size_read(inode); 1601 1602 end_index = i_size >> PAGE_CACHE_SHIFT; 1603 if (index > end_index) 1604 break; 1605 if (index == end_index) { 1606 nr = i_size & ~PAGE_CACHE_MASK; 1607 if (nr <= offset) 1608 break; 1609 } 1610 1611 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1612 if (desc->error) { 1613 if (desc->error == -EINVAL) 1614 desc->error = 0; 1615 break; 1616 } 1617 1618 /* 1619 * We must evaluate after, since reads (unlike writes) 1620 * are called without i_mutex protection against truncate 1621 */ 1622 nr = PAGE_CACHE_SIZE; 1623 i_size = i_size_read(inode); 1624 end_index = i_size >> PAGE_CACHE_SHIFT; 1625 if (index == end_index) { 1626 nr = i_size & ~PAGE_CACHE_MASK; 1627 if (nr <= offset) { 1628 if (page) 1629 page_cache_release(page); 1630 break; 1631 } 1632 } 1633 nr -= offset; 1634 1635 if (page) { 1636 /* 1637 * If users can be writing to this page using arbitrary 1638 * virtual addresses, take care about potential aliasing 1639 * before reading the page on the kernel side. 1640 */ 1641 if (mapping_writably_mapped(mapping)) 1642 flush_dcache_page(page); 1643 /* 1644 * Mark the page accessed if we read the beginning. 1645 */ 1646 if (!offset) 1647 mark_page_accessed(page); 1648 } else { 1649 page = ZERO_PAGE(0); 1650 page_cache_get(page); 1651 } 1652 1653 /* 1654 * Ok, we have the page, and it's up-to-date, so 1655 * now we can copy it to user space... 1656 * 1657 * The actor routine returns how many bytes were actually used.. 1658 * NOTE! This may not be the same as how much of a user buffer 1659 * we filled up (we may be padding etc), so we can only update 1660 * "pos" here (the actor routine has to update the user buffer 1661 * pointers and the remaining count). 1662 */ 1663 ret = actor(desc, page, offset, nr); 1664 offset += ret; 1665 index += offset >> PAGE_CACHE_SHIFT; 1666 offset &= ~PAGE_CACHE_MASK; 1667 1668 page_cache_release(page); 1669 if (ret != nr || !desc->count) 1670 break; 1671 1672 cond_resched(); 1673 } 1674 1675 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1676 file_accessed(filp); 1677} 1678 1679static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1680{ 1681 read_descriptor_t desc; 1682 1683 if ((ssize_t) count < 0) 1684 return -EINVAL; 1685 if (!access_ok(VERIFY_WRITE, buf, count)) 1686 return -EFAULT; 1687 if (!count) 1688 return 0; 1689 1690 desc.written = 0; 1691 desc.count = count; 1692 desc.arg.buf = buf; 1693 desc.error = 0; 1694 1695 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1696 if (desc.written) 1697 return desc.written; 1698 return desc.error; 1699} 1700 1701static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1702{ 1703 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1704 1705 buf->f_type = TMPFS_MAGIC; 1706 buf->f_bsize = PAGE_CACHE_SIZE; 1707 buf->f_namelen = NAME_MAX; 1708 spin_lock(&sbinfo->stat_lock); 1709 if (sbinfo->max_blocks) { 1710 buf->f_blocks = sbinfo->max_blocks; 1711 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1712 } 1713 if (sbinfo->max_inodes) { 1714 buf->f_files = sbinfo->max_inodes; 1715 buf->f_ffree = sbinfo->free_inodes; 1716 } 1717 /* else leave those fields 0 like simple_statfs */ 1718 spin_unlock(&sbinfo->stat_lock); 1719 return 0; 1720} 1721 1722/* 1723 * File creation. Allocate an inode, and we're done.. 1724 */ 1725static int 1726shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1727{ 1728 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1729 int error = -ENOSPC; 1730 1731 if (inode) { 1732 error = security_inode_init_security(inode, dir, NULL, NULL, 1733 NULL); 1734 if (error) { 1735 if (error != -EOPNOTSUPP) { 1736 iput(inode); 1737 return error; 1738 } 1739 } 1740 error = shmem_acl_init(inode, dir); 1741 if (error) { 1742 iput(inode); 1743 return error; 1744 } 1745 if (dir->i_mode & S_ISGID) { 1746 inode->i_gid = dir->i_gid; 1747 if (S_ISDIR(mode)) 1748 inode->i_mode |= S_ISGID; 1749 } 1750 dir->i_size += BOGO_DIRENT_SIZE; 1751 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1752 d_instantiate(dentry, inode); 1753 dget(dentry); /* Extra count - pin the dentry in core */ 1754 } 1755 return error; 1756} 1757 1758static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1759{ 1760 int error; 1761 1762 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1763 return error; 1764 inc_nlink(dir); 1765 return 0; 1766} 1767 1768static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1769 struct nameidata *nd) 1770{ 1771 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1772} 1773 1774/* 1775 * Link a file.. 1776 */ 1777static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1778{ 1779 struct inode *inode = old_dentry->d_inode; 1780 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1781 1782 /* 1783 * No ordinary (disk based) filesystem counts links as inodes; 1784 * but each new link needs a new dentry, pinning lowmem, and 1785 * tmpfs dentries cannot be pruned until they are unlinked. 1786 */ 1787 if (sbinfo->max_inodes) { 1788 spin_lock(&sbinfo->stat_lock); 1789 if (!sbinfo->free_inodes) { 1790 spin_unlock(&sbinfo->stat_lock); 1791 return -ENOSPC; 1792 } 1793 sbinfo->free_inodes--; 1794 spin_unlock(&sbinfo->stat_lock); 1795 } 1796 1797 dir->i_size += BOGO_DIRENT_SIZE; 1798 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1799 inc_nlink(inode); 1800 atomic_inc(&inode->i_count); /* New dentry reference */ 1801 dget(dentry); /* Extra pinning count for the created dentry */ 1802 d_instantiate(dentry, inode); 1803 return 0; 1804} 1805 1806static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1807{ 1808 struct inode *inode = dentry->d_inode; 1809 1810 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1811 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1812 if (sbinfo->max_inodes) { 1813 spin_lock(&sbinfo->stat_lock); 1814 sbinfo->free_inodes++; 1815 spin_unlock(&sbinfo->stat_lock); 1816 } 1817 } 1818 1819 dir->i_size -= BOGO_DIRENT_SIZE; 1820 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1821 drop_nlink(inode); 1822 dput(dentry); /* Undo the count from "create" - this does all the work */ 1823 return 0; 1824} 1825 1826static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1827{ 1828 if (!simple_empty(dentry)) 1829 return -ENOTEMPTY; 1830 1831 drop_nlink(dentry->d_inode); 1832 drop_nlink(dir); 1833 return shmem_unlink(dir, dentry); 1834} 1835 1836/* 1837 * The VFS layer already does all the dentry stuff for rename, 1838 * we just have to decrement the usage count for the target if 1839 * it exists so that the VFS layer correctly free's it when it 1840 * gets overwritten. 1841 */ 1842static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1843{ 1844 struct inode *inode = old_dentry->d_inode; 1845 int they_are_dirs = S_ISDIR(inode->i_mode); 1846 1847 if (!simple_empty(new_dentry)) 1848 return -ENOTEMPTY; 1849 1850 if (new_dentry->d_inode) { 1851 (void) shmem_unlink(new_dir, new_dentry); 1852 if (they_are_dirs) 1853 drop_nlink(old_dir); 1854 } else if (they_are_dirs) { 1855 drop_nlink(old_dir); 1856 inc_nlink(new_dir); 1857 } 1858 1859 old_dir->i_size -= BOGO_DIRENT_SIZE; 1860 new_dir->i_size += BOGO_DIRENT_SIZE; 1861 old_dir->i_ctime = old_dir->i_mtime = 1862 new_dir->i_ctime = new_dir->i_mtime = 1863 inode->i_ctime = CURRENT_TIME; 1864 return 0; 1865} 1866 1867static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1868{ 1869 int error; 1870 int len; 1871 struct inode *inode; 1872 struct page *page = NULL; 1873 char *kaddr; 1874 struct shmem_inode_info *info; 1875 1876 len = strlen(symname) + 1; 1877 if (len > PAGE_CACHE_SIZE) 1878 return -ENAMETOOLONG; 1879 1880 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1881 if (!inode) 1882 return -ENOSPC; 1883 1884 error = security_inode_init_security(inode, dir, NULL, NULL, 1885 NULL); 1886 if (error) { 1887 if (error != -EOPNOTSUPP) { 1888 iput(inode); 1889 return error; 1890 } 1891 error = 0; 1892 } 1893 1894 info = SHMEM_I(inode); 1895 inode->i_size = len-1; 1896 if (len <= (char *)inode - (char *)info) { 1897 /* do it inline */ 1898 memcpy(info, symname, len); 1899 inode->i_op = &shmem_symlink_inline_operations; 1900 } else { 1901 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1902 if (error) { 1903 iput(inode); 1904 return error; 1905 } 1906 inode->i_op = &shmem_symlink_inode_operations; 1907 kaddr = kmap_atomic(page, KM_USER0); 1908 memcpy(kaddr, symname, len); 1909 kunmap_atomic(kaddr, KM_USER0); 1910 set_page_dirty(page); 1911 page_cache_release(page); 1912 } 1913 if (dir->i_mode & S_ISGID) 1914 inode->i_gid = dir->i_gid; 1915 dir->i_size += BOGO_DIRENT_SIZE; 1916 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1917 d_instantiate(dentry, inode); 1918 dget(dentry); 1919 return 0; 1920} 1921 1922static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1923{ 1924 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1925 return NULL; 1926} 1927 1928static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1929{ 1930 struct page *page = NULL; 1931 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1932 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1933 return page; 1934} 1935 1936static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1937{ 1938 if (!IS_ERR(nd_get_link(nd))) { 1939 struct page *page = cookie; 1940 kunmap(page); 1941 mark_page_accessed(page); 1942 page_cache_release(page); 1943 } 1944} 1945 1946static const struct inode_operations shmem_symlink_inline_operations = { 1947 .readlink = generic_readlink, 1948 .follow_link = shmem_follow_link_inline, 1949}; 1950 1951static const struct inode_operations shmem_symlink_inode_operations = { 1952 .truncate = shmem_truncate, 1953 .readlink = generic_readlink, 1954 .follow_link = shmem_follow_link, 1955 .put_link = shmem_put_link, 1956}; 1957 1958#ifdef CONFIG_TMPFS_POSIX_ACL 1959/** 1960 * Superblocks without xattr inode operations will get security.* xattr 1961 * support from the VFS "for free". As soon as we have any other xattrs 1962 * like ACLs, we also need to implement the security.* handlers at 1963 * filesystem level, though. 1964 */ 1965 1966static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1967 size_t list_len, const char *name, 1968 size_t name_len) 1969{ 1970 return security_inode_listsecurity(inode, list, list_len); 1971} 1972 1973static int shmem_xattr_security_get(struct inode *inode, const char *name, 1974 void *buffer, size_t size) 1975{ 1976 if (strcmp(name, "") == 0) 1977 return -EINVAL; 1978 return security_inode_getsecurity(inode, name, buffer, size, 1979 -EOPNOTSUPP); 1980} 1981 1982static int shmem_xattr_security_set(struct inode *inode, const char *name, 1983 const void *value, size_t size, int flags) 1984{ 1985 if (strcmp(name, "") == 0) 1986 return -EINVAL; 1987 return security_inode_setsecurity(inode, name, value, size, flags); 1988} 1989 1990static struct xattr_handler shmem_xattr_security_handler = { 1991 .prefix = XATTR_SECURITY_PREFIX, 1992 .list = shmem_xattr_security_list, 1993 .get = shmem_xattr_security_get, 1994 .set = shmem_xattr_security_set, 1995}; 1996 1997static struct xattr_handler *shmem_xattr_handlers[] = { 1998 &shmem_xattr_acl_access_handler, 1999 &shmem_xattr_acl_default_handler, 2000 &shmem_xattr_security_handler, 2001 NULL 2002}; 2003#endif 2004 2005static struct dentry *shmem_get_parent(struct dentry *child) 2006{ 2007 return ERR_PTR(-ESTALE); 2008} 2009 2010static int shmem_match(struct inode *ino, void *vfh) 2011{ 2012 __u32 *fh = vfh; 2013 __u64 inum = fh[2]; 2014 inum = (inum << 32) | fh[1]; 2015 return ino->i_ino == inum && fh[0] == ino->i_generation; 2016} 2017 2018static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2019 struct fid *fid, int fh_len, int fh_type) 2020{ 2021 struct inode *inode; 2022 struct dentry *dentry = NULL; 2023 u64 inum = fid->raw[2]; 2024 inum = (inum << 32) | fid->raw[1]; 2025 2026 if (fh_len < 3) 2027 return NULL; 2028 2029 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2030 shmem_match, fid->raw); 2031 if (inode) { 2032 dentry = d_find_alias(inode); 2033 iput(inode); 2034 } 2035 2036 return dentry; 2037} 2038 2039static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2040 int connectable) 2041{ 2042 struct inode *inode = dentry->d_inode; 2043 2044 if (*len < 3) 2045 return 255; 2046 2047 if (hlist_unhashed(&inode->i_hash)) { 2048 /* Unfortunately insert_inode_hash is not idempotent, 2049 * so as we hash inodes here rather than at creation 2050 * time, we need a lock to ensure we only try 2051 * to do it once 2052 */ 2053 static DEFINE_SPINLOCK(lock); 2054 spin_lock(&lock); 2055 if (hlist_unhashed(&inode->i_hash)) 2056 __insert_inode_hash(inode, 2057 inode->i_ino + inode->i_generation); 2058 spin_unlock(&lock); 2059 } 2060 2061 fh[0] = inode->i_generation; 2062 fh[1] = inode->i_ino; 2063 fh[2] = ((__u64)inode->i_ino) >> 32; 2064 2065 *len = 3; 2066 return 1; 2067} 2068 2069static const struct export_operations shmem_export_ops = { 2070 .get_parent = shmem_get_parent, 2071 .encode_fh = shmem_encode_fh, 2072 .fh_to_dentry = shmem_fh_to_dentry, 2073}; 2074 2075static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2076 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2077 int *policy, nodemask_t *policy_nodes) 2078{ 2079 char *this_char, *value, *rest; 2080 2081 while (options != NULL) { 2082 this_char = options; 2083 for (;;) { 2084 /* 2085 * NUL-terminate this option: unfortunately, 2086 * mount options form a comma-separated list, 2087 * but mpol's nodelist may also contain commas. 2088 */ 2089 options = strchr(options, ','); 2090 if (options == NULL) 2091 break; 2092 options++; 2093 if (!isdigit(*options)) { 2094 options[-1] = '\0'; 2095 break; 2096 } 2097 } 2098 if (!*this_char) 2099 continue; 2100 if ((value = strchr(this_char,'=')) != NULL) { 2101 *value++ = 0; 2102 } else { 2103 printk(KERN_ERR 2104 "tmpfs: No value for mount option '%s'\n", 2105 this_char); 2106 return 1; 2107 } 2108 2109 if (!strcmp(this_char,"size")) { 2110 unsigned long long size; 2111 size = memparse(value,&rest); 2112 if (*rest == '%') { 2113 size <<= PAGE_SHIFT; 2114 size *= totalram_pages; 2115 do_div(size, 100); 2116 rest++; 2117 } 2118 if (*rest) 2119 goto bad_val; 2120 *blocks = size >> PAGE_CACHE_SHIFT; 2121 } else if (!strcmp(this_char,"nr_blocks")) { 2122 *blocks = memparse(value,&rest); 2123 if (*rest) 2124 goto bad_val; 2125 } else if (!strcmp(this_char,"nr_inodes")) { 2126 *inodes = memparse(value,&rest); 2127 if (*rest) 2128 goto bad_val; 2129 } else if (!strcmp(this_char,"mode")) { 2130 if (!mode) 2131 continue; 2132 *mode = simple_strtoul(value,&rest,8); 2133 if (*rest) 2134 goto bad_val; 2135 } else if (!strcmp(this_char,"uid")) { 2136 if (!uid) 2137 continue; 2138 *uid = simple_strtoul(value,&rest,0); 2139 if (*rest) 2140 goto bad_val; 2141 } else if (!strcmp(this_char,"gid")) { 2142 if (!gid) 2143 continue; 2144 *gid = simple_strtoul(value,&rest,0); 2145 if (*rest) 2146 goto bad_val; 2147 } else if (!strcmp(this_char,"mpol")) { 2148 if (shmem_parse_mpol(value,policy,policy_nodes)) 2149 goto bad_val; 2150 } else { 2151 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2152 this_char); 2153 return 1; 2154 } 2155 } 2156 return 0; 2157 2158bad_val: 2159 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2160 value, this_char); 2161 return 1; 2162 2163} 2164 2165static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2166{ 2167 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2168 unsigned long max_blocks = sbinfo->max_blocks; 2169 unsigned long max_inodes = sbinfo->max_inodes; 2170 int policy = sbinfo->policy; 2171 nodemask_t policy_nodes = sbinfo->policy_nodes; 2172 unsigned long blocks; 2173 unsigned long inodes; 2174 int error = -EINVAL; 2175 2176 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2177 &max_inodes, &policy, &policy_nodes)) 2178 return error; 2179 2180 spin_lock(&sbinfo->stat_lock); 2181 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2182 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2183 if (max_blocks < blocks) 2184 goto out; 2185 if (max_inodes < inodes) 2186 goto out; 2187 /* 2188 * Those tests also disallow limited->unlimited while any are in 2189 * use, so i_blocks will always be zero when max_blocks is zero; 2190 * but we must separately disallow unlimited->limited, because 2191 * in that case we have no record of how much is already in use. 2192 */ 2193 if (max_blocks && !sbinfo->max_blocks) 2194 goto out; 2195 if (max_inodes && !sbinfo->max_inodes) 2196 goto out; 2197 2198 error = 0; 2199 sbinfo->max_blocks = max_blocks; 2200 sbinfo->free_blocks = max_blocks - blocks; 2201 sbinfo->max_inodes = max_inodes; 2202 sbinfo->free_inodes = max_inodes - inodes; 2203 sbinfo->policy = policy; 2204 sbinfo->policy_nodes = policy_nodes; 2205out: 2206 spin_unlock(&sbinfo->stat_lock); 2207 return error; 2208} 2209#endif 2210 2211static void shmem_put_super(struct super_block *sb) 2212{ 2213 kfree(sb->s_fs_info); 2214 sb->s_fs_info = NULL; 2215} 2216 2217static int shmem_fill_super(struct super_block *sb, 2218 void *data, int silent) 2219{ 2220 struct inode *inode; 2221 struct dentry *root; 2222 int mode = S_IRWXUGO | S_ISVTX; 2223 uid_t uid = current->fsuid; 2224 gid_t gid = current->fsgid; 2225 int err = -ENOMEM; 2226 struct shmem_sb_info *sbinfo; 2227 unsigned long blocks = 0; 2228 unsigned long inodes = 0; 2229 int policy = MPOL_DEFAULT; 2230 nodemask_t policy_nodes = node_states[N_HIGH_MEMORY]; 2231 2232#ifdef CONFIG_TMPFS 2233 /* 2234 * Per default we only allow half of the physical ram per 2235 * tmpfs instance, limiting inodes to one per page of lowmem; 2236 * but the internal instance is left unlimited. 2237 */ 2238 if (!(sb->s_flags & MS_NOUSER)) { 2239 blocks = totalram_pages / 2; 2240 inodes = totalram_pages - totalhigh_pages; 2241 if (inodes > blocks) 2242 inodes = blocks; 2243 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2244 &inodes, &policy, &policy_nodes)) 2245 return -EINVAL; 2246 } 2247 sb->s_export_op = &shmem_export_ops; 2248#else 2249 sb->s_flags |= MS_NOUSER; 2250#endif 2251 2252 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2253 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2254 L1_CACHE_BYTES), GFP_KERNEL); 2255 if (!sbinfo) 2256 return -ENOMEM; 2257 2258 spin_lock_init(&sbinfo->stat_lock); 2259 sbinfo->max_blocks = blocks; 2260 sbinfo->free_blocks = blocks; 2261 sbinfo->max_inodes = inodes; 2262 sbinfo->free_inodes = inodes; 2263 sbinfo->policy = policy; 2264 sbinfo->policy_nodes = policy_nodes; 2265 2266 sb->s_fs_info = sbinfo; 2267 sb->s_maxbytes = SHMEM_MAX_BYTES; 2268 sb->s_blocksize = PAGE_CACHE_SIZE; 2269 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2270 sb->s_magic = TMPFS_MAGIC; 2271 sb->s_op = &shmem_ops; 2272 sb->s_time_gran = 1; 2273#ifdef CONFIG_TMPFS_POSIX_ACL 2274 sb->s_xattr = shmem_xattr_handlers; 2275 sb->s_flags |= MS_POSIXACL; 2276#endif 2277 2278 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2279 if (!inode) 2280 goto failed; 2281 inode->i_uid = uid; 2282 inode->i_gid = gid; 2283 root = d_alloc_root(inode); 2284 if (!root) 2285 goto failed_iput; 2286 sb->s_root = root; 2287 return 0; 2288 2289failed_iput: 2290 iput(inode); 2291failed: 2292 shmem_put_super(sb); 2293 return err; 2294} 2295 2296static struct kmem_cache *shmem_inode_cachep; 2297 2298static struct inode *shmem_alloc_inode(struct super_block *sb) 2299{ 2300 struct shmem_inode_info *p; 2301 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2302 if (!p) 2303 return NULL; 2304 return &p->vfs_inode; 2305} 2306 2307static void shmem_destroy_inode(struct inode *inode) 2308{ 2309 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2310 /* only struct inode is valid if it's an inline symlink */ 2311 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2312 } 2313 shmem_acl_destroy_inode(inode); 2314 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2315} 2316 2317static void init_once(struct kmem_cache *cachep, void *foo) 2318{ 2319 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2320 2321 inode_init_once(&p->vfs_inode); 2322#ifdef CONFIG_TMPFS_POSIX_ACL 2323 p->i_acl = NULL; 2324 p->i_default_acl = NULL; 2325#endif 2326} 2327 2328static int init_inodecache(void) 2329{ 2330 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2331 sizeof(struct shmem_inode_info), 2332 0, SLAB_PANIC, init_once); 2333 return 0; 2334} 2335 2336static void destroy_inodecache(void) 2337{ 2338 kmem_cache_destroy(shmem_inode_cachep); 2339} 2340 2341static const struct address_space_operations shmem_aops = { 2342 .writepage = shmem_writepage, 2343 .set_page_dirty = __set_page_dirty_no_writeback, 2344#ifdef CONFIG_TMPFS 2345 .readpage = shmem_readpage, 2346 .write_begin = shmem_write_begin, 2347 .write_end = shmem_write_end, 2348#endif 2349 .migratepage = migrate_page, 2350}; 2351 2352static const struct file_operations shmem_file_operations = { 2353 .mmap = shmem_mmap, 2354#ifdef CONFIG_TMPFS 2355 .llseek = generic_file_llseek, 2356 .read = shmem_file_read, 2357 .write = shmem_file_write, 2358 .fsync = simple_sync_file, 2359 .splice_read = generic_file_splice_read, 2360 .splice_write = generic_file_splice_write, 2361#endif 2362}; 2363 2364static const struct inode_operations shmem_inode_operations = { 2365 .truncate = shmem_truncate, 2366 .setattr = shmem_notify_change, 2367 .truncate_range = shmem_truncate_range, 2368#ifdef CONFIG_TMPFS_POSIX_ACL 2369 .setxattr = generic_setxattr, 2370 .getxattr = generic_getxattr, 2371 .listxattr = generic_listxattr, 2372 .removexattr = generic_removexattr, 2373 .permission = shmem_permission, 2374#endif 2375 2376}; 2377 2378static const struct inode_operations shmem_dir_inode_operations = { 2379#ifdef CONFIG_TMPFS 2380 .create = shmem_create, 2381 .lookup = simple_lookup, 2382 .link = shmem_link, 2383 .unlink = shmem_unlink, 2384 .symlink = shmem_symlink, 2385 .mkdir = shmem_mkdir, 2386 .rmdir = shmem_rmdir, 2387 .mknod = shmem_mknod, 2388 .rename = shmem_rename, 2389#endif 2390#ifdef CONFIG_TMPFS_POSIX_ACL 2391 .setattr = shmem_notify_change, 2392 .setxattr = generic_setxattr, 2393 .getxattr = generic_getxattr, 2394 .listxattr = generic_listxattr, 2395 .removexattr = generic_removexattr, 2396 .permission = shmem_permission, 2397#endif 2398}; 2399 2400static const struct inode_operations shmem_special_inode_operations = { 2401#ifdef CONFIG_TMPFS_POSIX_ACL 2402 .setattr = shmem_notify_change, 2403 .setxattr = generic_setxattr, 2404 .getxattr = generic_getxattr, 2405 .listxattr = generic_listxattr, 2406 .removexattr = generic_removexattr, 2407 .permission = shmem_permission, 2408#endif 2409}; 2410 2411static const struct super_operations shmem_ops = { 2412 .alloc_inode = shmem_alloc_inode, 2413 .destroy_inode = shmem_destroy_inode, 2414#ifdef CONFIG_TMPFS 2415 .statfs = shmem_statfs, 2416 .remount_fs = shmem_remount_fs, 2417#endif 2418 .delete_inode = shmem_delete_inode, 2419 .drop_inode = generic_delete_inode, 2420 .put_super = shmem_put_super, 2421}; 2422 2423static struct vm_operations_struct shmem_vm_ops = { 2424 .fault = shmem_fault, 2425#ifdef CONFIG_NUMA 2426 .set_policy = shmem_set_policy, 2427 .get_policy = shmem_get_policy, 2428#endif 2429}; 2430 2431 2432static int shmem_get_sb(struct file_system_type *fs_type, 2433 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2434{ 2435 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2436} 2437 2438static struct file_system_type tmpfs_fs_type = { 2439 .owner = THIS_MODULE, 2440 .name = "tmpfs", 2441 .get_sb = shmem_get_sb, 2442 .kill_sb = kill_litter_super, 2443}; 2444static struct vfsmount *shm_mnt; 2445 2446static int __init init_tmpfs(void) 2447{ 2448 int error; 2449 2450 error = bdi_init(&shmem_backing_dev_info); 2451 if (error) 2452 goto out4; 2453 2454 error = init_inodecache(); 2455 if (error) 2456 goto out3; 2457 2458 error = register_filesystem(&tmpfs_fs_type); 2459 if (error) { 2460 printk(KERN_ERR "Could not register tmpfs\n"); 2461 goto out2; 2462 } 2463 2464 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2465 tmpfs_fs_type.name, NULL); 2466 if (IS_ERR(shm_mnt)) { 2467 error = PTR_ERR(shm_mnt); 2468 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2469 goto out1; 2470 } 2471 return 0; 2472 2473out1: 2474 unregister_filesystem(&tmpfs_fs_type); 2475out2: 2476 destroy_inodecache(); 2477out3: 2478 bdi_destroy(&shmem_backing_dev_info); 2479out4: 2480 shm_mnt = ERR_PTR(error); 2481 return error; 2482} 2483module_init(init_tmpfs) 2484 2485/* 2486 * shmem_file_setup - get an unlinked file living in tmpfs 2487 * 2488 * @name: name for dentry (to be seen in /proc/<pid>/maps 2489 * @size: size to be set for the file 2490 * 2491 */ 2492struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2493{ 2494 int error; 2495 struct file *file; 2496 struct inode *inode; 2497 struct dentry *dentry, *root; 2498 struct qstr this; 2499 2500 if (IS_ERR(shm_mnt)) 2501 return (void *)shm_mnt; 2502 2503 if (size < 0 || size > SHMEM_MAX_BYTES) 2504 return ERR_PTR(-EINVAL); 2505 2506 if (shmem_acct_size(flags, size)) 2507 return ERR_PTR(-ENOMEM); 2508 2509 error = -ENOMEM; 2510 this.name = name; 2511 this.len = strlen(name); 2512 this.hash = 0; /* will go */ 2513 root = shm_mnt->mnt_root; 2514 dentry = d_alloc(root, &this); 2515 if (!dentry) 2516 goto put_memory; 2517 2518 error = -ENFILE; 2519 file = get_empty_filp(); 2520 if (!file) 2521 goto put_dentry; 2522 2523 error = -ENOSPC; 2524 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2525 if (!inode) 2526 goto close_file; 2527 2528 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2529 d_instantiate(dentry, inode); 2530 inode->i_size = size; 2531 inode->i_nlink = 0; /* It is unlinked */ 2532 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ, 2533 &shmem_file_operations); 2534 return file; 2535 2536close_file: 2537 put_filp(file); 2538put_dentry: 2539 dput(dentry); 2540put_memory: 2541 shmem_unacct_size(flags, size); 2542 return ERR_PTR(error); 2543} 2544 2545/* 2546 * shmem_zero_setup - setup a shared anonymous mapping 2547 * 2548 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2549 */ 2550int shmem_zero_setup(struct vm_area_struct *vma) 2551{ 2552 struct file *file; 2553 loff_t size = vma->vm_end - vma->vm_start; 2554 2555 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2556 if (IS_ERR(file)) 2557 return PTR_ERR(file); 2558 2559 if (vma->vm_file) 2560 fput(vma->vm_file); 2561 vma->vm_file = file; 2562 vma->vm_ops = &shmem_vm_ops; 2563 return 0; 2564} 2565