shmem.c revision 800d15a53e7d14fa26495b7b95d3bfe7877dd69d
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 * __GFP_MOVABLE is masked out as swap vectors cannot move 99 */ 100 return alloc_pages((gfp_mask & ~__GFP_MOVABLE) | __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 BUG_ON(page_mapped(page)); 919 920 mapping = page->mapping; 921 index = page->index; 922 inode = mapping->host; 923 info = SHMEM_I(inode); 924 if (info->flags & VM_LOCKED) 925 goto redirty; 926 swap = get_swap_page(); 927 if (!swap.val) 928 goto redirty; 929 930 spin_lock(&info->lock); 931 shmem_recalc_inode(inode); 932 if (index >= info->next_index) { 933 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 934 goto unlock; 935 } 936 entry = shmem_swp_entry(info, index, NULL); 937 BUG_ON(!entry); 938 BUG_ON(entry->val); 939 940 if (move_to_swap_cache(page, swap) == 0) { 941 shmem_swp_set(info, entry, swap.val); 942 shmem_swp_unmap(entry); 943 spin_unlock(&info->lock); 944 if (list_empty(&info->swaplist)) { 945 spin_lock(&shmem_swaplist_lock); 946 /* move instead of add in case we're racing */ 947 list_move_tail(&info->swaplist, &shmem_swaplist); 948 spin_unlock(&shmem_swaplist_lock); 949 } 950 unlock_page(page); 951 return 0; 952 } 953 954 shmem_swp_unmap(entry); 955unlock: 956 spin_unlock(&info->lock); 957 swap_free(swap); 958redirty: 959 set_page_dirty(page); 960 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ 961} 962 963#ifdef CONFIG_NUMA 964static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 965{ 966 char *nodelist = strchr(value, ':'); 967 int err = 1; 968 969 if (nodelist) { 970 /* NUL-terminate policy string */ 971 *nodelist++ = '\0'; 972 if (nodelist_parse(nodelist, *policy_nodes)) 973 goto out; 974 if (!nodes_subset(*policy_nodes, node_online_map)) 975 goto out; 976 } 977 if (!strcmp(value, "default")) { 978 *policy = MPOL_DEFAULT; 979 /* Don't allow a nodelist */ 980 if (!nodelist) 981 err = 0; 982 } else if (!strcmp(value, "prefer")) { 983 *policy = MPOL_PREFERRED; 984 /* Insist on a nodelist of one node only */ 985 if (nodelist) { 986 char *rest = nodelist; 987 while (isdigit(*rest)) 988 rest++; 989 if (!*rest) 990 err = 0; 991 } 992 } else if (!strcmp(value, "bind")) { 993 *policy = MPOL_BIND; 994 /* Insist on a nodelist */ 995 if (nodelist) 996 err = 0; 997 } else if (!strcmp(value, "interleave")) { 998 *policy = MPOL_INTERLEAVE; 999 /* Default to nodes online if no nodelist */ 1000 if (!nodelist) 1001 *policy_nodes = node_online_map; 1002 err = 0; 1003 } 1004out: 1005 /* Restore string for error message */ 1006 if (nodelist) 1007 *--nodelist = ':'; 1008 return err; 1009} 1010 1011static struct page *shmem_swapin_async(struct shared_policy *p, 1012 swp_entry_t entry, unsigned long idx) 1013{ 1014 struct page *page; 1015 struct vm_area_struct pvma; 1016 1017 /* Create a pseudo vma that just contains the policy */ 1018 memset(&pvma, 0, sizeof(struct vm_area_struct)); 1019 pvma.vm_end = PAGE_SIZE; 1020 pvma.vm_pgoff = idx; 1021 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 1022 page = read_swap_cache_async(entry, &pvma, 0); 1023 mpol_free(pvma.vm_policy); 1024 return page; 1025} 1026 1027struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 1028 unsigned long idx) 1029{ 1030 struct shared_policy *p = &info->policy; 1031 int i, num; 1032 struct page *page; 1033 unsigned long offset; 1034 1035 num = valid_swaphandles(entry, &offset); 1036 for (i = 0; i < num; offset++, i++) { 1037 page = shmem_swapin_async(p, 1038 swp_entry(swp_type(entry), offset), idx); 1039 if (!page) 1040 break; 1041 page_cache_release(page); 1042 } 1043 lru_add_drain(); /* Push any new pages onto the LRU now */ 1044 return shmem_swapin_async(p, entry, idx); 1045} 1046 1047static struct page * 1048shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, 1049 unsigned long idx) 1050{ 1051 struct vm_area_struct pvma; 1052 struct page *page; 1053 1054 memset(&pvma, 0, sizeof(struct vm_area_struct)); 1055 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1056 pvma.vm_pgoff = idx; 1057 pvma.vm_end = PAGE_SIZE; 1058 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 1059 mpol_free(pvma.vm_policy); 1060 return page; 1061} 1062#else 1063static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 1064{ 1065 return 1; 1066} 1067 1068static inline struct page * 1069shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 1070{ 1071 swapin_readahead(entry, 0, NULL); 1072 return read_swap_cache_async(entry, NULL, 0); 1073} 1074 1075static inline struct page * 1076shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) 1077{ 1078 return alloc_page(gfp | __GFP_ZERO); 1079} 1080#endif 1081 1082/* 1083 * shmem_getpage - either get the page from swap or allocate a new one 1084 * 1085 * If we allocate a new one we do not mark it dirty. That's up to the 1086 * vm. If we swap it in we mark it dirty since we also free the swap 1087 * entry since a page cannot live in both the swap and page cache 1088 */ 1089static int shmem_getpage(struct inode *inode, unsigned long idx, 1090 struct page **pagep, enum sgp_type sgp, int *type) 1091{ 1092 struct address_space *mapping = inode->i_mapping; 1093 struct shmem_inode_info *info = SHMEM_I(inode); 1094 struct shmem_sb_info *sbinfo; 1095 struct page *filepage = *pagep; 1096 struct page *swappage; 1097 swp_entry_t *entry; 1098 swp_entry_t swap; 1099 int error; 1100 1101 if (idx >= SHMEM_MAX_INDEX) 1102 return -EFBIG; 1103 1104 if (type) 1105 *type = 0; 1106 1107 /* 1108 * Normally, filepage is NULL on entry, and either found 1109 * uptodate immediately, or allocated and zeroed, or read 1110 * in under swappage, which is then assigned to filepage. 1111 * But shmem_readpage and shmem_write_begin pass in a locked 1112 * filepage, which may be found not uptodate by other callers 1113 * too, and may need to be copied from the swappage read in. 1114 */ 1115repeat: 1116 if (!filepage) 1117 filepage = find_lock_page(mapping, idx); 1118 if (filepage && PageUptodate(filepage)) 1119 goto done; 1120 error = 0; 1121 if (sgp == SGP_QUICK) 1122 goto failed; 1123 1124 spin_lock(&info->lock); 1125 shmem_recalc_inode(inode); 1126 entry = shmem_swp_alloc(info, idx, sgp); 1127 if (IS_ERR(entry)) { 1128 spin_unlock(&info->lock); 1129 error = PTR_ERR(entry); 1130 goto failed; 1131 } 1132 swap = *entry; 1133 1134 if (swap.val) { 1135 /* Look it up and read it in.. */ 1136 swappage = lookup_swap_cache(swap); 1137 if (!swappage) { 1138 shmem_swp_unmap(entry); 1139 /* here we actually do the io */ 1140 if (type && !(*type & VM_FAULT_MAJOR)) { 1141 __count_vm_event(PGMAJFAULT); 1142 *type |= VM_FAULT_MAJOR; 1143 } 1144 spin_unlock(&info->lock); 1145 swappage = shmem_swapin(info, swap, idx); 1146 if (!swappage) { 1147 spin_lock(&info->lock); 1148 entry = shmem_swp_alloc(info, idx, sgp); 1149 if (IS_ERR(entry)) 1150 error = PTR_ERR(entry); 1151 else { 1152 if (entry->val == swap.val) 1153 error = -ENOMEM; 1154 shmem_swp_unmap(entry); 1155 } 1156 spin_unlock(&info->lock); 1157 if (error) 1158 goto failed; 1159 goto repeat; 1160 } 1161 wait_on_page_locked(swappage); 1162 page_cache_release(swappage); 1163 goto repeat; 1164 } 1165 1166 /* We have to do this with page locked to prevent races */ 1167 if (TestSetPageLocked(swappage)) { 1168 shmem_swp_unmap(entry); 1169 spin_unlock(&info->lock); 1170 wait_on_page_locked(swappage); 1171 page_cache_release(swappage); 1172 goto repeat; 1173 } 1174 if (PageWriteback(swappage)) { 1175 shmem_swp_unmap(entry); 1176 spin_unlock(&info->lock); 1177 wait_on_page_writeback(swappage); 1178 unlock_page(swappage); 1179 page_cache_release(swappage); 1180 goto repeat; 1181 } 1182 if (!PageUptodate(swappage)) { 1183 shmem_swp_unmap(entry); 1184 spin_unlock(&info->lock); 1185 unlock_page(swappage); 1186 page_cache_release(swappage); 1187 error = -EIO; 1188 goto failed; 1189 } 1190 1191 if (filepage) { 1192 shmem_swp_set(info, entry, 0); 1193 shmem_swp_unmap(entry); 1194 delete_from_swap_cache(swappage); 1195 spin_unlock(&info->lock); 1196 copy_highpage(filepage, swappage); 1197 unlock_page(swappage); 1198 page_cache_release(swappage); 1199 flush_dcache_page(filepage); 1200 SetPageUptodate(filepage); 1201 set_page_dirty(filepage); 1202 swap_free(swap); 1203 } else if (!(error = move_from_swap_cache( 1204 swappage, idx, mapping))) { 1205 info->flags |= SHMEM_PAGEIN; 1206 shmem_swp_set(info, entry, 0); 1207 shmem_swp_unmap(entry); 1208 spin_unlock(&info->lock); 1209 filepage = swappage; 1210 swap_free(swap); 1211 } else { 1212 shmem_swp_unmap(entry); 1213 spin_unlock(&info->lock); 1214 unlock_page(swappage); 1215 page_cache_release(swappage); 1216 if (error == -ENOMEM) { 1217 /* let kswapd refresh zone for GFP_ATOMICs */ 1218 congestion_wait(WRITE, HZ/50); 1219 } 1220 goto repeat; 1221 } 1222 } else if (sgp == SGP_READ && !filepage) { 1223 shmem_swp_unmap(entry); 1224 filepage = find_get_page(mapping, idx); 1225 if (filepage && 1226 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1227 spin_unlock(&info->lock); 1228 wait_on_page_locked(filepage); 1229 page_cache_release(filepage); 1230 filepage = NULL; 1231 goto repeat; 1232 } 1233 spin_unlock(&info->lock); 1234 } else { 1235 shmem_swp_unmap(entry); 1236 sbinfo = SHMEM_SB(inode->i_sb); 1237 if (sbinfo->max_blocks) { 1238 spin_lock(&sbinfo->stat_lock); 1239 if (sbinfo->free_blocks == 0 || 1240 shmem_acct_block(info->flags)) { 1241 spin_unlock(&sbinfo->stat_lock); 1242 spin_unlock(&info->lock); 1243 error = -ENOSPC; 1244 goto failed; 1245 } 1246 sbinfo->free_blocks--; 1247 inode->i_blocks += BLOCKS_PER_PAGE; 1248 spin_unlock(&sbinfo->stat_lock); 1249 } else if (shmem_acct_block(info->flags)) { 1250 spin_unlock(&info->lock); 1251 error = -ENOSPC; 1252 goto failed; 1253 } 1254 1255 if (!filepage) { 1256 spin_unlock(&info->lock); 1257 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1258 info, 1259 idx); 1260 if (!filepage) { 1261 shmem_unacct_blocks(info->flags, 1); 1262 shmem_free_blocks(inode, 1); 1263 error = -ENOMEM; 1264 goto failed; 1265 } 1266 1267 spin_lock(&info->lock); 1268 entry = shmem_swp_alloc(info, idx, sgp); 1269 if (IS_ERR(entry)) 1270 error = PTR_ERR(entry); 1271 else { 1272 swap = *entry; 1273 shmem_swp_unmap(entry); 1274 } 1275 if (error || swap.val || 0 != add_to_page_cache_lru( 1276 filepage, mapping, idx, GFP_ATOMIC)) { 1277 spin_unlock(&info->lock); 1278 page_cache_release(filepage); 1279 shmem_unacct_blocks(info->flags, 1); 1280 shmem_free_blocks(inode, 1); 1281 filepage = NULL; 1282 if (error) 1283 goto failed; 1284 goto repeat; 1285 } 1286 info->flags |= SHMEM_PAGEIN; 1287 } 1288 1289 info->alloced++; 1290 spin_unlock(&info->lock); 1291 flush_dcache_page(filepage); 1292 SetPageUptodate(filepage); 1293 } 1294done: 1295 if (*pagep != filepage) { 1296 *pagep = filepage; 1297 if (sgp != SGP_FAULT) 1298 unlock_page(filepage); 1299 1300 } 1301 return 0; 1302 1303failed: 1304 if (*pagep != filepage) { 1305 unlock_page(filepage); 1306 page_cache_release(filepage); 1307 } 1308 return error; 1309} 1310 1311static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1312{ 1313 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1314 int error; 1315 int ret; 1316 1317 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1318 return VM_FAULT_SIGBUS; 1319 1320 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_FAULT, &ret); 1321 if (error) 1322 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1323 1324 mark_page_accessed(vmf->page); 1325 return ret | VM_FAULT_LOCKED; 1326} 1327 1328#ifdef CONFIG_NUMA 1329int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1330{ 1331 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1332 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1333} 1334 1335struct mempolicy * 1336shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) 1337{ 1338 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1339 unsigned long idx; 1340 1341 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1342 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1343} 1344#endif 1345 1346int shmem_lock(struct file *file, int lock, struct user_struct *user) 1347{ 1348 struct inode *inode = file->f_path.dentry->d_inode; 1349 struct shmem_inode_info *info = SHMEM_I(inode); 1350 int retval = -ENOMEM; 1351 1352 spin_lock(&info->lock); 1353 if (lock && !(info->flags & VM_LOCKED)) { 1354 if (!user_shm_lock(inode->i_size, user)) 1355 goto out_nomem; 1356 info->flags |= VM_LOCKED; 1357 } 1358 if (!lock && (info->flags & VM_LOCKED) && user) { 1359 user_shm_unlock(inode->i_size, user); 1360 info->flags &= ~VM_LOCKED; 1361 } 1362 retval = 0; 1363out_nomem: 1364 spin_unlock(&info->lock); 1365 return retval; 1366} 1367 1368static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1369{ 1370 file_accessed(file); 1371 vma->vm_ops = &shmem_vm_ops; 1372 vma->vm_flags |= VM_CAN_NONLINEAR; 1373 return 0; 1374} 1375 1376static struct inode * 1377shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1378{ 1379 struct inode *inode; 1380 struct shmem_inode_info *info; 1381 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1382 1383 if (sbinfo->max_inodes) { 1384 spin_lock(&sbinfo->stat_lock); 1385 if (!sbinfo->free_inodes) { 1386 spin_unlock(&sbinfo->stat_lock); 1387 return NULL; 1388 } 1389 sbinfo->free_inodes--; 1390 spin_unlock(&sbinfo->stat_lock); 1391 } 1392 1393 inode = new_inode(sb); 1394 if (inode) { 1395 inode->i_mode = mode; 1396 inode->i_uid = current->fsuid; 1397 inode->i_gid = current->fsgid; 1398 inode->i_blocks = 0; 1399 inode->i_mapping->a_ops = &shmem_aops; 1400 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1401 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1402 inode->i_generation = get_seconds(); 1403 info = SHMEM_I(inode); 1404 memset(info, 0, (char *)inode - (char *)info); 1405 spin_lock_init(&info->lock); 1406 INIT_LIST_HEAD(&info->swaplist); 1407 1408 switch (mode & S_IFMT) { 1409 default: 1410 inode->i_op = &shmem_special_inode_operations; 1411 init_special_inode(inode, mode, dev); 1412 break; 1413 case S_IFREG: 1414 inode->i_op = &shmem_inode_operations; 1415 inode->i_fop = &shmem_file_operations; 1416 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1417 &sbinfo->policy_nodes); 1418 break; 1419 case S_IFDIR: 1420 inc_nlink(inode); 1421 /* Some things misbehave if size == 0 on a directory */ 1422 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1423 inode->i_op = &shmem_dir_inode_operations; 1424 inode->i_fop = &simple_dir_operations; 1425 break; 1426 case S_IFLNK: 1427 /* 1428 * Must not load anything in the rbtree, 1429 * mpol_free_shared_policy will not be called. 1430 */ 1431 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1432 NULL); 1433 break; 1434 } 1435 } else if (sbinfo->max_inodes) { 1436 spin_lock(&sbinfo->stat_lock); 1437 sbinfo->free_inodes++; 1438 spin_unlock(&sbinfo->stat_lock); 1439 } 1440 return inode; 1441} 1442 1443#ifdef CONFIG_TMPFS 1444static const struct inode_operations shmem_symlink_inode_operations; 1445static const struct inode_operations shmem_symlink_inline_operations; 1446 1447/* 1448 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1449 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1450 * below the loop driver, in the generic fashion that many filesystems support. 1451 */ 1452static int shmem_readpage(struct file *file, struct page *page) 1453{ 1454 struct inode *inode = page->mapping->host; 1455 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1456 unlock_page(page); 1457 return error; 1458} 1459 1460static int 1461shmem_write_begin(struct file *file, struct address_space *mapping, 1462 loff_t pos, unsigned len, unsigned flags, 1463 struct page **pagep, void **fsdata) 1464{ 1465 struct inode *inode = mapping->host; 1466 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1467 *pagep = NULL; 1468 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1469} 1470 1471static int 1472shmem_write_end(struct file *file, struct address_space *mapping, 1473 loff_t pos, unsigned len, unsigned copied, 1474 struct page *page, void *fsdata) 1475{ 1476 struct inode *inode = mapping->host; 1477 1478 set_page_dirty(page); 1479 page_cache_release(page); 1480 1481 if (pos+copied > inode->i_size) 1482 i_size_write(inode, pos+copied); 1483 1484 return copied; 1485} 1486 1487static ssize_t 1488shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1489{ 1490 struct inode *inode = file->f_path.dentry->d_inode; 1491 loff_t pos; 1492 unsigned long written; 1493 ssize_t err; 1494 1495 if ((ssize_t) count < 0) 1496 return -EINVAL; 1497 1498 if (!access_ok(VERIFY_READ, buf, count)) 1499 return -EFAULT; 1500 1501 mutex_lock(&inode->i_mutex); 1502 1503 pos = *ppos; 1504 written = 0; 1505 1506 err = generic_write_checks(file, &pos, &count, 0); 1507 if (err || !count) 1508 goto out; 1509 1510 err = remove_suid(file->f_path.dentry); 1511 if (err) 1512 goto out; 1513 1514 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1515 1516 do { 1517 struct page *page = NULL; 1518 unsigned long bytes, index, offset; 1519 char *kaddr; 1520 int left; 1521 1522 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1523 index = pos >> PAGE_CACHE_SHIFT; 1524 bytes = PAGE_CACHE_SIZE - offset; 1525 if (bytes > count) 1526 bytes = count; 1527 1528 /* 1529 * We don't hold page lock across copy from user - 1530 * what would it guard against? - so no deadlock here. 1531 * But it still may be a good idea to prefault below. 1532 */ 1533 1534 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1535 if (err) 1536 break; 1537 1538 left = bytes; 1539 if (PageHighMem(page)) { 1540 volatile unsigned char dummy; 1541 __get_user(dummy, buf); 1542 __get_user(dummy, buf + bytes - 1); 1543 1544 kaddr = kmap_atomic(page, KM_USER0); 1545 left = __copy_from_user_inatomic(kaddr + offset, 1546 buf, bytes); 1547 kunmap_atomic(kaddr, KM_USER0); 1548 } 1549 if (left) { 1550 kaddr = kmap(page); 1551 left = __copy_from_user(kaddr + offset, buf, bytes); 1552 kunmap(page); 1553 } 1554 1555 written += bytes; 1556 count -= bytes; 1557 pos += bytes; 1558 buf += bytes; 1559 if (pos > inode->i_size) 1560 i_size_write(inode, pos); 1561 1562 flush_dcache_page(page); 1563 set_page_dirty(page); 1564 mark_page_accessed(page); 1565 page_cache_release(page); 1566 1567 if (left) { 1568 pos -= left; 1569 written -= left; 1570 err = -EFAULT; 1571 break; 1572 } 1573 1574 /* 1575 * Our dirty pages are not counted in nr_dirty, 1576 * and we do not attempt to balance dirty pages. 1577 */ 1578 1579 cond_resched(); 1580 } while (count); 1581 1582 *ppos = pos; 1583 if (written) 1584 err = written; 1585out: 1586 mutex_unlock(&inode->i_mutex); 1587 return err; 1588} 1589 1590static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1591{ 1592 struct inode *inode = filp->f_path.dentry->d_inode; 1593 struct address_space *mapping = inode->i_mapping; 1594 unsigned long index, offset; 1595 1596 index = *ppos >> PAGE_CACHE_SHIFT; 1597 offset = *ppos & ~PAGE_CACHE_MASK; 1598 1599 for (;;) { 1600 struct page *page = NULL; 1601 unsigned long end_index, nr, ret; 1602 loff_t i_size = i_size_read(inode); 1603 1604 end_index = i_size >> PAGE_CACHE_SHIFT; 1605 if (index > end_index) 1606 break; 1607 if (index == end_index) { 1608 nr = i_size & ~PAGE_CACHE_MASK; 1609 if (nr <= offset) 1610 break; 1611 } 1612 1613 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1614 if (desc->error) { 1615 if (desc->error == -EINVAL) 1616 desc->error = 0; 1617 break; 1618 } 1619 1620 /* 1621 * We must evaluate after, since reads (unlike writes) 1622 * are called without i_mutex protection against truncate 1623 */ 1624 nr = PAGE_CACHE_SIZE; 1625 i_size = i_size_read(inode); 1626 end_index = i_size >> PAGE_CACHE_SHIFT; 1627 if (index == end_index) { 1628 nr = i_size & ~PAGE_CACHE_MASK; 1629 if (nr <= offset) { 1630 if (page) 1631 page_cache_release(page); 1632 break; 1633 } 1634 } 1635 nr -= offset; 1636 1637 if (page) { 1638 /* 1639 * If users can be writing to this page using arbitrary 1640 * virtual addresses, take care about potential aliasing 1641 * before reading the page on the kernel side. 1642 */ 1643 if (mapping_writably_mapped(mapping)) 1644 flush_dcache_page(page); 1645 /* 1646 * Mark the page accessed if we read the beginning. 1647 */ 1648 if (!offset) 1649 mark_page_accessed(page); 1650 } else { 1651 page = ZERO_PAGE(0); 1652 page_cache_get(page); 1653 } 1654 1655 /* 1656 * Ok, we have the page, and it's up-to-date, so 1657 * now we can copy it to user space... 1658 * 1659 * The actor routine returns how many bytes were actually used.. 1660 * NOTE! This may not be the same as how much of a user buffer 1661 * we filled up (we may be padding etc), so we can only update 1662 * "pos" here (the actor routine has to update the user buffer 1663 * pointers and the remaining count). 1664 */ 1665 ret = actor(desc, page, offset, nr); 1666 offset += ret; 1667 index += offset >> PAGE_CACHE_SHIFT; 1668 offset &= ~PAGE_CACHE_MASK; 1669 1670 page_cache_release(page); 1671 if (ret != nr || !desc->count) 1672 break; 1673 1674 cond_resched(); 1675 } 1676 1677 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1678 file_accessed(filp); 1679} 1680 1681static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1682{ 1683 read_descriptor_t desc; 1684 1685 if ((ssize_t) count < 0) 1686 return -EINVAL; 1687 if (!access_ok(VERIFY_WRITE, buf, count)) 1688 return -EFAULT; 1689 if (!count) 1690 return 0; 1691 1692 desc.written = 0; 1693 desc.count = count; 1694 desc.arg.buf = buf; 1695 desc.error = 0; 1696 1697 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1698 if (desc.written) 1699 return desc.written; 1700 return desc.error; 1701} 1702 1703static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1704{ 1705 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1706 1707 buf->f_type = TMPFS_MAGIC; 1708 buf->f_bsize = PAGE_CACHE_SIZE; 1709 buf->f_namelen = NAME_MAX; 1710 spin_lock(&sbinfo->stat_lock); 1711 if (sbinfo->max_blocks) { 1712 buf->f_blocks = sbinfo->max_blocks; 1713 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1714 } 1715 if (sbinfo->max_inodes) { 1716 buf->f_files = sbinfo->max_inodes; 1717 buf->f_ffree = sbinfo->free_inodes; 1718 } 1719 /* else leave those fields 0 like simple_statfs */ 1720 spin_unlock(&sbinfo->stat_lock); 1721 return 0; 1722} 1723 1724/* 1725 * File creation. Allocate an inode, and we're done.. 1726 */ 1727static int 1728shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1729{ 1730 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1731 int error = -ENOSPC; 1732 1733 if (inode) { 1734 error = security_inode_init_security(inode, dir, NULL, NULL, 1735 NULL); 1736 if (error) { 1737 if (error != -EOPNOTSUPP) { 1738 iput(inode); 1739 return error; 1740 } 1741 } 1742 error = shmem_acl_init(inode, dir); 1743 if (error) { 1744 iput(inode); 1745 return error; 1746 } 1747 if (dir->i_mode & S_ISGID) { 1748 inode->i_gid = dir->i_gid; 1749 if (S_ISDIR(mode)) 1750 inode->i_mode |= S_ISGID; 1751 } 1752 dir->i_size += BOGO_DIRENT_SIZE; 1753 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1754 d_instantiate(dentry, inode); 1755 dget(dentry); /* Extra count - pin the dentry in core */ 1756 } 1757 return error; 1758} 1759 1760static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1761{ 1762 int error; 1763 1764 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1765 return error; 1766 inc_nlink(dir); 1767 return 0; 1768} 1769 1770static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1771 struct nameidata *nd) 1772{ 1773 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1774} 1775 1776/* 1777 * Link a file.. 1778 */ 1779static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1780{ 1781 struct inode *inode = old_dentry->d_inode; 1782 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1783 1784 /* 1785 * No ordinary (disk based) filesystem counts links as inodes; 1786 * but each new link needs a new dentry, pinning lowmem, and 1787 * tmpfs dentries cannot be pruned until they are unlinked. 1788 */ 1789 if (sbinfo->max_inodes) { 1790 spin_lock(&sbinfo->stat_lock); 1791 if (!sbinfo->free_inodes) { 1792 spin_unlock(&sbinfo->stat_lock); 1793 return -ENOSPC; 1794 } 1795 sbinfo->free_inodes--; 1796 spin_unlock(&sbinfo->stat_lock); 1797 } 1798 1799 dir->i_size += BOGO_DIRENT_SIZE; 1800 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1801 inc_nlink(inode); 1802 atomic_inc(&inode->i_count); /* New dentry reference */ 1803 dget(dentry); /* Extra pinning count for the created dentry */ 1804 d_instantiate(dentry, inode); 1805 return 0; 1806} 1807 1808static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1809{ 1810 struct inode *inode = dentry->d_inode; 1811 1812 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1813 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1814 if (sbinfo->max_inodes) { 1815 spin_lock(&sbinfo->stat_lock); 1816 sbinfo->free_inodes++; 1817 spin_unlock(&sbinfo->stat_lock); 1818 } 1819 } 1820 1821 dir->i_size -= BOGO_DIRENT_SIZE; 1822 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1823 drop_nlink(inode); 1824 dput(dentry); /* Undo the count from "create" - this does all the work */ 1825 return 0; 1826} 1827 1828static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1829{ 1830 if (!simple_empty(dentry)) 1831 return -ENOTEMPTY; 1832 1833 drop_nlink(dentry->d_inode); 1834 drop_nlink(dir); 1835 return shmem_unlink(dir, dentry); 1836} 1837 1838/* 1839 * The VFS layer already does all the dentry stuff for rename, 1840 * we just have to decrement the usage count for the target if 1841 * it exists so that the VFS layer correctly free's it when it 1842 * gets overwritten. 1843 */ 1844static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1845{ 1846 struct inode *inode = old_dentry->d_inode; 1847 int they_are_dirs = S_ISDIR(inode->i_mode); 1848 1849 if (!simple_empty(new_dentry)) 1850 return -ENOTEMPTY; 1851 1852 if (new_dentry->d_inode) { 1853 (void) shmem_unlink(new_dir, new_dentry); 1854 if (they_are_dirs) 1855 drop_nlink(old_dir); 1856 } else if (they_are_dirs) { 1857 drop_nlink(old_dir); 1858 inc_nlink(new_dir); 1859 } 1860 1861 old_dir->i_size -= BOGO_DIRENT_SIZE; 1862 new_dir->i_size += BOGO_DIRENT_SIZE; 1863 old_dir->i_ctime = old_dir->i_mtime = 1864 new_dir->i_ctime = new_dir->i_mtime = 1865 inode->i_ctime = CURRENT_TIME; 1866 return 0; 1867} 1868 1869static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1870{ 1871 int error; 1872 int len; 1873 struct inode *inode; 1874 struct page *page = NULL; 1875 char *kaddr; 1876 struct shmem_inode_info *info; 1877 1878 len = strlen(symname) + 1; 1879 if (len > PAGE_CACHE_SIZE) 1880 return -ENAMETOOLONG; 1881 1882 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1883 if (!inode) 1884 return -ENOSPC; 1885 1886 error = security_inode_init_security(inode, dir, NULL, NULL, 1887 NULL); 1888 if (error) { 1889 if (error != -EOPNOTSUPP) { 1890 iput(inode); 1891 return error; 1892 } 1893 error = 0; 1894 } 1895 1896 info = SHMEM_I(inode); 1897 inode->i_size = len-1; 1898 if (len <= (char *)inode - (char *)info) { 1899 /* do it inline */ 1900 memcpy(info, symname, len); 1901 inode->i_op = &shmem_symlink_inline_operations; 1902 } else { 1903 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1904 if (error) { 1905 iput(inode); 1906 return error; 1907 } 1908 inode->i_op = &shmem_symlink_inode_operations; 1909 kaddr = kmap_atomic(page, KM_USER0); 1910 memcpy(kaddr, symname, len); 1911 kunmap_atomic(kaddr, KM_USER0); 1912 set_page_dirty(page); 1913 page_cache_release(page); 1914 } 1915 if (dir->i_mode & S_ISGID) 1916 inode->i_gid = dir->i_gid; 1917 dir->i_size += BOGO_DIRENT_SIZE; 1918 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1919 d_instantiate(dentry, inode); 1920 dget(dentry); 1921 return 0; 1922} 1923 1924static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1925{ 1926 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1927 return NULL; 1928} 1929 1930static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1931{ 1932 struct page *page = NULL; 1933 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1934 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1935 return page; 1936} 1937 1938static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1939{ 1940 if (!IS_ERR(nd_get_link(nd))) { 1941 struct page *page = cookie; 1942 kunmap(page); 1943 mark_page_accessed(page); 1944 page_cache_release(page); 1945 } 1946} 1947 1948static const struct inode_operations shmem_symlink_inline_operations = { 1949 .readlink = generic_readlink, 1950 .follow_link = shmem_follow_link_inline, 1951}; 1952 1953static const struct inode_operations shmem_symlink_inode_operations = { 1954 .truncate = shmem_truncate, 1955 .readlink = generic_readlink, 1956 .follow_link = shmem_follow_link, 1957 .put_link = shmem_put_link, 1958}; 1959 1960#ifdef CONFIG_TMPFS_POSIX_ACL 1961/** 1962 * Superblocks without xattr inode operations will get security.* xattr 1963 * support from the VFS "for free". As soon as we have any other xattrs 1964 * like ACLs, we also need to implement the security.* handlers at 1965 * filesystem level, though. 1966 */ 1967 1968static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1969 size_t list_len, const char *name, 1970 size_t name_len) 1971{ 1972 return security_inode_listsecurity(inode, list, list_len); 1973} 1974 1975static int shmem_xattr_security_get(struct inode *inode, const char *name, 1976 void *buffer, size_t size) 1977{ 1978 if (strcmp(name, "") == 0) 1979 return -EINVAL; 1980 return security_inode_getsecurity(inode, name, buffer, size, 1981 -EOPNOTSUPP); 1982} 1983 1984static int shmem_xattr_security_set(struct inode *inode, const char *name, 1985 const void *value, size_t size, int flags) 1986{ 1987 if (strcmp(name, "") == 0) 1988 return -EINVAL; 1989 return security_inode_setsecurity(inode, name, value, size, flags); 1990} 1991 1992static struct xattr_handler shmem_xattr_security_handler = { 1993 .prefix = XATTR_SECURITY_PREFIX, 1994 .list = shmem_xattr_security_list, 1995 .get = shmem_xattr_security_get, 1996 .set = shmem_xattr_security_set, 1997}; 1998 1999static struct xattr_handler *shmem_xattr_handlers[] = { 2000 &shmem_xattr_acl_access_handler, 2001 &shmem_xattr_acl_default_handler, 2002 &shmem_xattr_security_handler, 2003 NULL 2004}; 2005#endif 2006 2007static struct dentry *shmem_get_parent(struct dentry *child) 2008{ 2009 return ERR_PTR(-ESTALE); 2010} 2011 2012static int shmem_match(struct inode *ino, void *vfh) 2013{ 2014 __u32 *fh = vfh; 2015 __u64 inum = fh[2]; 2016 inum = (inum << 32) | fh[1]; 2017 return ino->i_ino == inum && fh[0] == ino->i_generation; 2018} 2019 2020static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh) 2021{ 2022 struct dentry *de = NULL; 2023 struct inode *inode; 2024 __u32 *fh = vfh; 2025 __u64 inum = fh[2]; 2026 inum = (inum << 32) | fh[1]; 2027 2028 inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh); 2029 if (inode) { 2030 de = d_find_alias(inode); 2031 iput(inode); 2032 } 2033 2034 return de? de: ERR_PTR(-ESTALE); 2035} 2036 2037static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh, 2038 int len, int type, 2039 int (*acceptable)(void *context, struct dentry *de), 2040 void *context) 2041{ 2042 if (len < 3) 2043 return ERR_PTR(-ESTALE); 2044 2045 return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable, 2046 context); 2047} 2048 2049static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2050 int connectable) 2051{ 2052 struct inode *inode = dentry->d_inode; 2053 2054 if (*len < 3) 2055 return 255; 2056 2057 if (hlist_unhashed(&inode->i_hash)) { 2058 /* Unfortunately insert_inode_hash is not idempotent, 2059 * so as we hash inodes here rather than at creation 2060 * time, we need a lock to ensure we only try 2061 * to do it once 2062 */ 2063 static DEFINE_SPINLOCK(lock); 2064 spin_lock(&lock); 2065 if (hlist_unhashed(&inode->i_hash)) 2066 __insert_inode_hash(inode, 2067 inode->i_ino + inode->i_generation); 2068 spin_unlock(&lock); 2069 } 2070 2071 fh[0] = inode->i_generation; 2072 fh[1] = inode->i_ino; 2073 fh[2] = ((__u64)inode->i_ino) >> 32; 2074 2075 *len = 3; 2076 return 1; 2077} 2078 2079static struct export_operations shmem_export_ops = { 2080 .get_parent = shmem_get_parent, 2081 .get_dentry = shmem_get_dentry, 2082 .encode_fh = shmem_encode_fh, 2083 .decode_fh = shmem_decode_fh, 2084}; 2085 2086static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2087 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2088 int *policy, nodemask_t *policy_nodes) 2089{ 2090 char *this_char, *value, *rest; 2091 2092 while (options != NULL) { 2093 this_char = options; 2094 for (;;) { 2095 /* 2096 * NUL-terminate this option: unfortunately, 2097 * mount options form a comma-separated list, 2098 * but mpol's nodelist may also contain commas. 2099 */ 2100 options = strchr(options, ','); 2101 if (options == NULL) 2102 break; 2103 options++; 2104 if (!isdigit(*options)) { 2105 options[-1] = '\0'; 2106 break; 2107 } 2108 } 2109 if (!*this_char) 2110 continue; 2111 if ((value = strchr(this_char,'=')) != NULL) { 2112 *value++ = 0; 2113 } else { 2114 printk(KERN_ERR 2115 "tmpfs: No value for mount option '%s'\n", 2116 this_char); 2117 return 1; 2118 } 2119 2120 if (!strcmp(this_char,"size")) { 2121 unsigned long long size; 2122 size = memparse(value,&rest); 2123 if (*rest == '%') { 2124 size <<= PAGE_SHIFT; 2125 size *= totalram_pages; 2126 do_div(size, 100); 2127 rest++; 2128 } 2129 if (*rest) 2130 goto bad_val; 2131 *blocks = size >> PAGE_CACHE_SHIFT; 2132 } else if (!strcmp(this_char,"nr_blocks")) { 2133 *blocks = memparse(value,&rest); 2134 if (*rest) 2135 goto bad_val; 2136 } else if (!strcmp(this_char,"nr_inodes")) { 2137 *inodes = memparse(value,&rest); 2138 if (*rest) 2139 goto bad_val; 2140 } else if (!strcmp(this_char,"mode")) { 2141 if (!mode) 2142 continue; 2143 *mode = simple_strtoul(value,&rest,8); 2144 if (*rest) 2145 goto bad_val; 2146 } else if (!strcmp(this_char,"uid")) { 2147 if (!uid) 2148 continue; 2149 *uid = simple_strtoul(value,&rest,0); 2150 if (*rest) 2151 goto bad_val; 2152 } else if (!strcmp(this_char,"gid")) { 2153 if (!gid) 2154 continue; 2155 *gid = simple_strtoul(value,&rest,0); 2156 if (*rest) 2157 goto bad_val; 2158 } else if (!strcmp(this_char,"mpol")) { 2159 if (shmem_parse_mpol(value,policy,policy_nodes)) 2160 goto bad_val; 2161 } else { 2162 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2163 this_char); 2164 return 1; 2165 } 2166 } 2167 return 0; 2168 2169bad_val: 2170 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2171 value, this_char); 2172 return 1; 2173 2174} 2175 2176static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2177{ 2178 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2179 unsigned long max_blocks = sbinfo->max_blocks; 2180 unsigned long max_inodes = sbinfo->max_inodes; 2181 int policy = sbinfo->policy; 2182 nodemask_t policy_nodes = sbinfo->policy_nodes; 2183 unsigned long blocks; 2184 unsigned long inodes; 2185 int error = -EINVAL; 2186 2187 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2188 &max_inodes, &policy, &policy_nodes)) 2189 return error; 2190 2191 spin_lock(&sbinfo->stat_lock); 2192 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2193 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2194 if (max_blocks < blocks) 2195 goto out; 2196 if (max_inodes < inodes) 2197 goto out; 2198 /* 2199 * Those tests also disallow limited->unlimited while any are in 2200 * use, so i_blocks will always be zero when max_blocks is zero; 2201 * but we must separately disallow unlimited->limited, because 2202 * in that case we have no record of how much is already in use. 2203 */ 2204 if (max_blocks && !sbinfo->max_blocks) 2205 goto out; 2206 if (max_inodes && !sbinfo->max_inodes) 2207 goto out; 2208 2209 error = 0; 2210 sbinfo->max_blocks = max_blocks; 2211 sbinfo->free_blocks = max_blocks - blocks; 2212 sbinfo->max_inodes = max_inodes; 2213 sbinfo->free_inodes = max_inodes - inodes; 2214 sbinfo->policy = policy; 2215 sbinfo->policy_nodes = policy_nodes; 2216out: 2217 spin_unlock(&sbinfo->stat_lock); 2218 return error; 2219} 2220#endif 2221 2222static void shmem_put_super(struct super_block *sb) 2223{ 2224 kfree(sb->s_fs_info); 2225 sb->s_fs_info = NULL; 2226} 2227 2228static int shmem_fill_super(struct super_block *sb, 2229 void *data, int silent) 2230{ 2231 struct inode *inode; 2232 struct dentry *root; 2233 int mode = S_IRWXUGO | S_ISVTX; 2234 uid_t uid = current->fsuid; 2235 gid_t gid = current->fsgid; 2236 int err = -ENOMEM; 2237 struct shmem_sb_info *sbinfo; 2238 unsigned long blocks = 0; 2239 unsigned long inodes = 0; 2240 int policy = MPOL_DEFAULT; 2241 nodemask_t policy_nodes = node_online_map; 2242 2243#ifdef CONFIG_TMPFS 2244 /* 2245 * Per default we only allow half of the physical ram per 2246 * tmpfs instance, limiting inodes to one per page of lowmem; 2247 * but the internal instance is left unlimited. 2248 */ 2249 if (!(sb->s_flags & MS_NOUSER)) { 2250 blocks = totalram_pages / 2; 2251 inodes = totalram_pages - totalhigh_pages; 2252 if (inodes > blocks) 2253 inodes = blocks; 2254 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2255 &inodes, &policy, &policy_nodes)) 2256 return -EINVAL; 2257 } 2258 sb->s_export_op = &shmem_export_ops; 2259#else 2260 sb->s_flags |= MS_NOUSER; 2261#endif 2262 2263 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2264 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2265 L1_CACHE_BYTES), GFP_KERNEL); 2266 if (!sbinfo) 2267 return -ENOMEM; 2268 2269 spin_lock_init(&sbinfo->stat_lock); 2270 sbinfo->max_blocks = blocks; 2271 sbinfo->free_blocks = blocks; 2272 sbinfo->max_inodes = inodes; 2273 sbinfo->free_inodes = inodes; 2274 sbinfo->policy = policy; 2275 sbinfo->policy_nodes = policy_nodes; 2276 2277 sb->s_fs_info = sbinfo; 2278 sb->s_maxbytes = SHMEM_MAX_BYTES; 2279 sb->s_blocksize = PAGE_CACHE_SIZE; 2280 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2281 sb->s_magic = TMPFS_MAGIC; 2282 sb->s_op = &shmem_ops; 2283 sb->s_time_gran = 1; 2284#ifdef CONFIG_TMPFS_POSIX_ACL 2285 sb->s_xattr = shmem_xattr_handlers; 2286 sb->s_flags |= MS_POSIXACL; 2287#endif 2288 2289 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2290 if (!inode) 2291 goto failed; 2292 inode->i_uid = uid; 2293 inode->i_gid = gid; 2294 root = d_alloc_root(inode); 2295 if (!root) 2296 goto failed_iput; 2297 sb->s_root = root; 2298 return 0; 2299 2300failed_iput: 2301 iput(inode); 2302failed: 2303 shmem_put_super(sb); 2304 return err; 2305} 2306 2307static struct kmem_cache *shmem_inode_cachep; 2308 2309static struct inode *shmem_alloc_inode(struct super_block *sb) 2310{ 2311 struct shmem_inode_info *p; 2312 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2313 if (!p) 2314 return NULL; 2315 return &p->vfs_inode; 2316} 2317 2318static void shmem_destroy_inode(struct inode *inode) 2319{ 2320 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2321 /* only struct inode is valid if it's an inline symlink */ 2322 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2323 } 2324 shmem_acl_destroy_inode(inode); 2325 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2326} 2327 2328static void init_once(void *foo, struct kmem_cache *cachep, 2329 unsigned long flags) 2330{ 2331 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2332 2333 inode_init_once(&p->vfs_inode); 2334#ifdef CONFIG_TMPFS_POSIX_ACL 2335 p->i_acl = NULL; 2336 p->i_default_acl = NULL; 2337#endif 2338} 2339 2340static int init_inodecache(void) 2341{ 2342 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2343 sizeof(struct shmem_inode_info), 2344 0, 0, init_once); 2345 if (shmem_inode_cachep == NULL) 2346 return -ENOMEM; 2347 return 0; 2348} 2349 2350static void destroy_inodecache(void) 2351{ 2352 kmem_cache_destroy(shmem_inode_cachep); 2353} 2354 2355static const struct address_space_operations shmem_aops = { 2356 .writepage = shmem_writepage, 2357 .set_page_dirty = __set_page_dirty_no_writeback, 2358#ifdef CONFIG_TMPFS 2359 .readpage = shmem_readpage, 2360 .write_begin = shmem_write_begin, 2361 .write_end = shmem_write_end, 2362#endif 2363 .migratepage = migrate_page, 2364}; 2365 2366static const struct file_operations shmem_file_operations = { 2367 .mmap = shmem_mmap, 2368#ifdef CONFIG_TMPFS 2369 .llseek = generic_file_llseek, 2370 .read = shmem_file_read, 2371 .write = shmem_file_write, 2372 .fsync = simple_sync_file, 2373 .splice_read = generic_file_splice_read, 2374 .splice_write = generic_file_splice_write, 2375#endif 2376}; 2377 2378static const struct inode_operations shmem_inode_operations = { 2379 .truncate = shmem_truncate, 2380 .setattr = shmem_notify_change, 2381 .truncate_range = shmem_truncate_range, 2382#ifdef CONFIG_TMPFS_POSIX_ACL 2383 .setxattr = generic_setxattr, 2384 .getxattr = generic_getxattr, 2385 .listxattr = generic_listxattr, 2386 .removexattr = generic_removexattr, 2387 .permission = shmem_permission, 2388#endif 2389 2390}; 2391 2392static const struct inode_operations shmem_dir_inode_operations = { 2393#ifdef CONFIG_TMPFS 2394 .create = shmem_create, 2395 .lookup = simple_lookup, 2396 .link = shmem_link, 2397 .unlink = shmem_unlink, 2398 .symlink = shmem_symlink, 2399 .mkdir = shmem_mkdir, 2400 .rmdir = shmem_rmdir, 2401 .mknod = shmem_mknod, 2402 .rename = shmem_rename, 2403#endif 2404#ifdef CONFIG_TMPFS_POSIX_ACL 2405 .setattr = shmem_notify_change, 2406 .setxattr = generic_setxattr, 2407 .getxattr = generic_getxattr, 2408 .listxattr = generic_listxattr, 2409 .removexattr = generic_removexattr, 2410 .permission = shmem_permission, 2411#endif 2412}; 2413 2414static const struct inode_operations shmem_special_inode_operations = { 2415#ifdef CONFIG_TMPFS_POSIX_ACL 2416 .setattr = shmem_notify_change, 2417 .setxattr = generic_setxattr, 2418 .getxattr = generic_getxattr, 2419 .listxattr = generic_listxattr, 2420 .removexattr = generic_removexattr, 2421 .permission = shmem_permission, 2422#endif 2423}; 2424 2425static const struct super_operations shmem_ops = { 2426 .alloc_inode = shmem_alloc_inode, 2427 .destroy_inode = shmem_destroy_inode, 2428#ifdef CONFIG_TMPFS 2429 .statfs = shmem_statfs, 2430 .remount_fs = shmem_remount_fs, 2431#endif 2432 .delete_inode = shmem_delete_inode, 2433 .drop_inode = generic_delete_inode, 2434 .put_super = shmem_put_super, 2435}; 2436 2437static struct vm_operations_struct shmem_vm_ops = { 2438 .fault = shmem_fault, 2439#ifdef CONFIG_NUMA 2440 .set_policy = shmem_set_policy, 2441 .get_policy = shmem_get_policy, 2442#endif 2443}; 2444 2445 2446static int shmem_get_sb(struct file_system_type *fs_type, 2447 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2448{ 2449 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2450} 2451 2452static struct file_system_type tmpfs_fs_type = { 2453 .owner = THIS_MODULE, 2454 .name = "tmpfs", 2455 .get_sb = shmem_get_sb, 2456 .kill_sb = kill_litter_super, 2457}; 2458static struct vfsmount *shm_mnt; 2459 2460static int __init init_tmpfs(void) 2461{ 2462 int error; 2463 2464 error = init_inodecache(); 2465 if (error) 2466 goto out3; 2467 2468 error = register_filesystem(&tmpfs_fs_type); 2469 if (error) { 2470 printk(KERN_ERR "Could not register tmpfs\n"); 2471 goto out2; 2472 } 2473 2474 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2475 tmpfs_fs_type.name, NULL); 2476 if (IS_ERR(shm_mnt)) { 2477 error = PTR_ERR(shm_mnt); 2478 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2479 goto out1; 2480 } 2481 return 0; 2482 2483out1: 2484 unregister_filesystem(&tmpfs_fs_type); 2485out2: 2486 destroy_inodecache(); 2487out3: 2488 shm_mnt = ERR_PTR(error); 2489 return error; 2490} 2491module_init(init_tmpfs) 2492 2493/* 2494 * shmem_file_setup - get an unlinked file living in tmpfs 2495 * 2496 * @name: name for dentry (to be seen in /proc/<pid>/maps 2497 * @size: size to be set for the file 2498 * 2499 */ 2500struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2501{ 2502 int error; 2503 struct file *file; 2504 struct inode *inode; 2505 struct dentry *dentry, *root; 2506 struct qstr this; 2507 2508 if (IS_ERR(shm_mnt)) 2509 return (void *)shm_mnt; 2510 2511 if (size < 0 || size > SHMEM_MAX_BYTES) 2512 return ERR_PTR(-EINVAL); 2513 2514 if (shmem_acct_size(flags, size)) 2515 return ERR_PTR(-ENOMEM); 2516 2517 error = -ENOMEM; 2518 this.name = name; 2519 this.len = strlen(name); 2520 this.hash = 0; /* will go */ 2521 root = shm_mnt->mnt_root; 2522 dentry = d_alloc(root, &this); 2523 if (!dentry) 2524 goto put_memory; 2525 2526 error = -ENFILE; 2527 file = get_empty_filp(); 2528 if (!file) 2529 goto put_dentry; 2530 2531 error = -ENOSPC; 2532 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2533 if (!inode) 2534 goto close_file; 2535 2536 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2537 d_instantiate(dentry, inode); 2538 inode->i_size = size; 2539 inode->i_nlink = 0; /* It is unlinked */ 2540 file->f_path.mnt = mntget(shm_mnt); 2541 file->f_path.dentry = dentry; 2542 file->f_mapping = inode->i_mapping; 2543 file->f_op = &shmem_file_operations; 2544 file->f_mode = FMODE_WRITE | FMODE_READ; 2545 return file; 2546 2547close_file: 2548 put_filp(file); 2549put_dentry: 2550 dput(dentry); 2551put_memory: 2552 shmem_unacct_size(flags, size); 2553 return ERR_PTR(error); 2554} 2555 2556/* 2557 * shmem_zero_setup - setup a shared anonymous mapping 2558 * 2559 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2560 */ 2561int shmem_zero_setup(struct vm_area_struct *vma) 2562{ 2563 struct file *file; 2564 loff_t size = vma->vm_end - vma->vm_start; 2565 2566 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2567 if (IS_ERR(file)) 2568 return PTR_ERR(file); 2569 2570 if (vma->vm_file) 2571 fput(vma->vm_file); 2572 vma->vm_file = file; 2573 vma->vm_ops = &shmem_vm_ops; 2574 return 0; 2575} 2576