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 */ 80 enum 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 88 static int shmem_getpage(struct inode *inode, unsigned long idx, 89 struct page **pagep, enum sgp_type sgp, int *type); 90 91 static 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 } 103 104 static inline void shmem_dir_free(struct page *page) 105 { 106 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 107 } 108 109 static struct page **shmem_dir_map(struct page *page) 110 { 111 return (struct page **)kmap_atomic(page, KM_USER0); 112 } 113 114 static inline void shmem_dir_unmap(struct page **dir) 115 { 116 kunmap_atomic(dir, KM_USER0); 117 } 118 119 static swp_entry_t *shmem_swp_map(struct page *page) 120 { 121 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 122 } 123 124 static 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 } 135 136 static inline void shmem_swp_unmap(swp_entry_t *entry) 137 { 138 kunmap_atomic(entry, KM_USER1); 139 } 140 141 static 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 */ 152 static 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 } 157 158 static 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 */ 170 static 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 } 175 176 static 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 } 181 182 static const struct super_operations shmem_ops; 183 static const struct address_space_operations shmem_aops; 184 static const struct file_operations shmem_file_operations; 185 static const struct inode_operations shmem_inode_operations; 186 static const struct inode_operations shmem_dir_inode_operations; 187 static const struct inode_operations shmem_special_inode_operations; 188 static struct vm_operations_struct shmem_vm_ops; 189 190 static 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 }; 195 196 static LIST_HEAD(shmem_swaplist); 197 static DEFINE_SPINLOCK(shmem_swaplist_lock); 198 199 static 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 */ 223 static 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 */ 274 static 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 } 327 328 static 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 */ 348 static 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 */ 413 static 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 } 438 439 static 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 } 465 466 static 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 } 482 483 static 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 } 671 done1: 672 shmem_dir_unmap(dir); 673 done2: 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 } 709 710 static void shmem_truncate(struct inode *inode) 711 { 712 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 713 } 714 715 static 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 } 762 763 static 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 } 787 788 static 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 } 798 799 static 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 } 859 lost1: 860 shmem_dir_unmap(dir-1); 861 lost2: 862 spin_unlock(&info->lock); 863 return 0; 864 found: 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 */ 884 int 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 */ 909 static 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); 970 unlock: 971 spin_unlock(&info->lock); 972 swap_free(swap); 973 redirty: 974 set_page_dirty(page); 975 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ 976 } 977 978 #ifdef CONFIG_NUMA 979 static 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 } 1021 out: 1022 /* Restore string for error message */ 1023 if (nodelist) 1024 *--nodelist = ':'; 1025 return err; 1026 } 1027 1028 static struct page *shmem_swapin_async(struct shared_policy *p, 1029 swp_entry_t entry, unsigned long idx) 1030 { 1031 struct page *page; 1032 struct vm_area_struct pvma; 1033 1034 /* Create a pseudo vma that just contains the policy */ 1035 memset(&pvma, 0, sizeof(struct vm_area_struct)); 1036 pvma.vm_end = PAGE_SIZE; 1037 pvma.vm_pgoff = idx; 1038 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 1039 page = read_swap_cache_async(entry, &pvma, 0); 1040 mpol_free(pvma.vm_policy); 1041 return page; 1042 } 1043 1044 static struct page *shmem_swapin(struct shmem_inode_info *info, 1045 swp_entry_t entry, unsigned long idx) 1046 { 1047 struct shared_policy *p = &info->policy; 1048 int i, num; 1049 struct page *page; 1050 unsigned long offset; 1051 1052 num = valid_swaphandles(entry, &offset); 1053 for (i = 0; i < num; offset++, i++) { 1054 page = shmem_swapin_async(p, 1055 swp_entry(swp_type(entry), offset), idx); 1056 if (!page) 1057 break; 1058 page_cache_release(page); 1059 } 1060 lru_add_drain(); /* Push any new pages onto the LRU now */ 1061 return shmem_swapin_async(p, entry, idx); 1062 } 1063 1064 static struct page * 1065 shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, 1066 unsigned long idx) 1067 { 1068 struct vm_area_struct pvma; 1069 struct page *page; 1070 1071 memset(&pvma, 0, sizeof(struct vm_area_struct)); 1072 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1073 pvma.vm_pgoff = idx; 1074 pvma.vm_end = PAGE_SIZE; 1075 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 1076 mpol_free(pvma.vm_policy); 1077 return page; 1078 } 1079 #else 1080 static inline int shmem_parse_mpol(char *value, int *policy, 1081 nodemask_t *policy_nodes) 1082 { 1083 return 1; 1084 } 1085 1086 static inline struct page * 1087 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 1088 { 1089 swapin_readahead(entry, 0, NULL); 1090 return read_swap_cache_async(entry, NULL, 0); 1091 } 1092 1093 static inline struct page * 1094 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) 1095 { 1096 return alloc_page(gfp | __GFP_ZERO); 1097 } 1098 #endif 1099 1100 /* 1101 * shmem_getpage - either get the page from swap or allocate a new one 1102 * 1103 * If we allocate a new one we do not mark it dirty. That's up to the 1104 * vm. If we swap it in we mark it dirty since we also free the swap 1105 * entry since a page cannot live in both the swap and page cache 1106 */ 1107 static int shmem_getpage(struct inode *inode, unsigned long idx, 1108 struct page **pagep, enum sgp_type sgp, int *type) 1109 { 1110 struct address_space *mapping = inode->i_mapping; 1111 struct shmem_inode_info *info = SHMEM_I(inode); 1112 struct shmem_sb_info *sbinfo; 1113 struct page *filepage = *pagep; 1114 struct page *swappage; 1115 swp_entry_t *entry; 1116 swp_entry_t swap; 1117 int error; 1118 1119 if (idx >= SHMEM_MAX_INDEX) 1120 return -EFBIG; 1121 1122 if (type) 1123 *type = 0; 1124 1125 /* 1126 * Normally, filepage is NULL on entry, and either found 1127 * uptodate immediately, or allocated and zeroed, or read 1128 * in under swappage, which is then assigned to filepage. 1129 * But shmem_readpage and shmem_write_begin pass in a locked 1130 * filepage, which may be found not uptodate by other callers 1131 * too, and may need to be copied from the swappage read in. 1132 */ 1133 repeat: 1134 if (!filepage) 1135 filepage = find_lock_page(mapping, idx); 1136 if (filepage && PageUptodate(filepage)) 1137 goto done; 1138 error = 0; 1139 if (sgp == SGP_QUICK) 1140 goto failed; 1141 1142 spin_lock(&info->lock); 1143 shmem_recalc_inode(inode); 1144 entry = shmem_swp_alloc(info, idx, sgp); 1145 if (IS_ERR(entry)) { 1146 spin_unlock(&info->lock); 1147 error = PTR_ERR(entry); 1148 goto failed; 1149 } 1150 swap = *entry; 1151 1152 if (swap.val) { 1153 /* Look it up and read it in.. */ 1154 swappage = lookup_swap_cache(swap); 1155 if (!swappage) { 1156 shmem_swp_unmap(entry); 1157 /* here we actually do the io */ 1158 if (type && !(*type & VM_FAULT_MAJOR)) { 1159 __count_vm_event(PGMAJFAULT); 1160 *type |= VM_FAULT_MAJOR; 1161 } 1162 spin_unlock(&info->lock); 1163 swappage = shmem_swapin(info, swap, idx); 1164 if (!swappage) { 1165 spin_lock(&info->lock); 1166 entry = shmem_swp_alloc(info, idx, sgp); 1167 if (IS_ERR(entry)) 1168 error = PTR_ERR(entry); 1169 else { 1170 if (entry->val == swap.val) 1171 error = -ENOMEM; 1172 shmem_swp_unmap(entry); 1173 } 1174 spin_unlock(&info->lock); 1175 if (error) 1176 goto failed; 1177 goto repeat; 1178 } 1179 wait_on_page_locked(swappage); 1180 page_cache_release(swappage); 1181 goto repeat; 1182 } 1183 1184 /* We have to do this with page locked to prevent races */ 1185 if (TestSetPageLocked(swappage)) { 1186 shmem_swp_unmap(entry); 1187 spin_unlock(&info->lock); 1188 wait_on_page_locked(swappage); 1189 page_cache_release(swappage); 1190 goto repeat; 1191 } 1192 if (PageWriteback(swappage)) { 1193 shmem_swp_unmap(entry); 1194 spin_unlock(&info->lock); 1195 wait_on_page_writeback(swappage); 1196 unlock_page(swappage); 1197 page_cache_release(swappage); 1198 goto repeat; 1199 } 1200 if (!PageUptodate(swappage)) { 1201 shmem_swp_unmap(entry); 1202 spin_unlock(&info->lock); 1203 unlock_page(swappage); 1204 page_cache_release(swappage); 1205 error = -EIO; 1206 goto failed; 1207 } 1208 1209 if (filepage) { 1210 shmem_swp_set(info, entry, 0); 1211 shmem_swp_unmap(entry); 1212 delete_from_swap_cache(swappage); 1213 spin_unlock(&info->lock); 1214 copy_highpage(filepage, swappage); 1215 unlock_page(swappage); 1216 page_cache_release(swappage); 1217 flush_dcache_page(filepage); 1218 SetPageUptodate(filepage); 1219 set_page_dirty(filepage); 1220 swap_free(swap); 1221 } else if (!(error = move_from_swap_cache( 1222 swappage, idx, mapping))) { 1223 info->flags |= SHMEM_PAGEIN; 1224 shmem_swp_set(info, entry, 0); 1225 shmem_swp_unmap(entry); 1226 spin_unlock(&info->lock); 1227 filepage = swappage; 1228 swap_free(swap); 1229 } else { 1230 shmem_swp_unmap(entry); 1231 spin_unlock(&info->lock); 1232 unlock_page(swappage); 1233 page_cache_release(swappage); 1234 if (error == -ENOMEM) { 1235 /* let kswapd refresh zone for GFP_ATOMICs */ 1236 congestion_wait(WRITE, HZ/50); 1237 } 1238 goto repeat; 1239 } 1240 } else if (sgp == SGP_READ && !filepage) { 1241 shmem_swp_unmap(entry); 1242 filepage = find_get_page(mapping, idx); 1243 if (filepage && 1244 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1245 spin_unlock(&info->lock); 1246 wait_on_page_locked(filepage); 1247 page_cache_release(filepage); 1248 filepage = NULL; 1249 goto repeat; 1250 } 1251 spin_unlock(&info->lock); 1252 } else { 1253 shmem_swp_unmap(entry); 1254 sbinfo = SHMEM_SB(inode->i_sb); 1255 if (sbinfo->max_blocks) { 1256 spin_lock(&sbinfo->stat_lock); 1257 if (sbinfo->free_blocks == 0 || 1258 shmem_acct_block(info->flags)) { 1259 spin_unlock(&sbinfo->stat_lock); 1260 spin_unlock(&info->lock); 1261 error = -ENOSPC; 1262 goto failed; 1263 } 1264 sbinfo->free_blocks--; 1265 inode->i_blocks += BLOCKS_PER_PAGE; 1266 spin_unlock(&sbinfo->stat_lock); 1267 } else if (shmem_acct_block(info->flags)) { 1268 spin_unlock(&info->lock); 1269 error = -ENOSPC; 1270 goto failed; 1271 } 1272 1273 if (!filepage) { 1274 spin_unlock(&info->lock); 1275 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1276 info, 1277 idx); 1278 if (!filepage) { 1279 shmem_unacct_blocks(info->flags, 1); 1280 shmem_free_blocks(inode, 1); 1281 error = -ENOMEM; 1282 goto failed; 1283 } 1284 1285 spin_lock(&info->lock); 1286 entry = shmem_swp_alloc(info, idx, sgp); 1287 if (IS_ERR(entry)) 1288 error = PTR_ERR(entry); 1289 else { 1290 swap = *entry; 1291 shmem_swp_unmap(entry); 1292 } 1293 if (error || swap.val || 0 != add_to_page_cache_lru( 1294 filepage, mapping, idx, GFP_ATOMIC)) { 1295 spin_unlock(&info->lock); 1296 page_cache_release(filepage); 1297 shmem_unacct_blocks(info->flags, 1); 1298 shmem_free_blocks(inode, 1); 1299 filepage = NULL; 1300 if (error) 1301 goto failed; 1302 goto repeat; 1303 } 1304 info->flags |= SHMEM_PAGEIN; 1305 } 1306 1307 info->alloced++; 1308 spin_unlock(&info->lock); 1309 flush_dcache_page(filepage); 1310 SetPageUptodate(filepage); 1311 } 1312 done: 1313 if (*pagep != filepage) { 1314 *pagep = filepage; 1315 if (sgp != SGP_FAULT) 1316 unlock_page(filepage); 1317 1318 } 1319 return 0; 1320 1321 failed: 1322 if (*pagep != filepage) { 1323 unlock_page(filepage); 1324 page_cache_release(filepage); 1325 } 1326 return error; 1327 } 1328 1329 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1330 { 1331 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1332 int error; 1333 int ret; 1334 1335 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1336 return VM_FAULT_SIGBUS; 1337 1338 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_FAULT, &ret); 1339 if (error) 1340 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1341 1342 mark_page_accessed(vmf->page); 1343 return ret | VM_FAULT_LOCKED; 1344 } 1345 1346 #ifdef CONFIG_NUMA 1347 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1348 { 1349 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1350 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1351 } 1352 1353 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1354 unsigned long addr) 1355 { 1356 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1357 unsigned long idx; 1358 1359 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1360 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1361 } 1362 #endif 1363 1364 int shmem_lock(struct file *file, int lock, struct user_struct *user) 1365 { 1366 struct inode *inode = file->f_path.dentry->d_inode; 1367 struct shmem_inode_info *info = SHMEM_I(inode); 1368 int retval = -ENOMEM; 1369 1370 spin_lock(&info->lock); 1371 if (lock && !(info->flags & VM_LOCKED)) { 1372 if (!user_shm_lock(inode->i_size, user)) 1373 goto out_nomem; 1374 info->flags |= VM_LOCKED; 1375 } 1376 if (!lock && (info->flags & VM_LOCKED) && user) { 1377 user_shm_unlock(inode->i_size, user); 1378 info->flags &= ~VM_LOCKED; 1379 } 1380 retval = 0; 1381 out_nomem: 1382 spin_unlock(&info->lock); 1383 return retval; 1384 } 1385 1386 static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1387 { 1388 file_accessed(file); 1389 vma->vm_ops = &shmem_vm_ops; 1390 vma->vm_flags |= VM_CAN_NONLINEAR; 1391 return 0; 1392 } 1393 1394 static struct inode * 1395 shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1396 { 1397 struct inode *inode; 1398 struct shmem_inode_info *info; 1399 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1400 1401 if (sbinfo->max_inodes) { 1402 spin_lock(&sbinfo->stat_lock); 1403 if (!sbinfo->free_inodes) { 1404 spin_unlock(&sbinfo->stat_lock); 1405 return NULL; 1406 } 1407 sbinfo->free_inodes--; 1408 spin_unlock(&sbinfo->stat_lock); 1409 } 1410 1411 inode = new_inode(sb); 1412 if (inode) { 1413 inode->i_mode = mode; 1414 inode->i_uid = current->fsuid; 1415 inode->i_gid = current->fsgid; 1416 inode->i_blocks = 0; 1417 inode->i_mapping->a_ops = &shmem_aops; 1418 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1419 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1420 inode->i_generation = get_seconds(); 1421 info = SHMEM_I(inode); 1422 memset(info, 0, (char *)inode - (char *)info); 1423 spin_lock_init(&info->lock); 1424 INIT_LIST_HEAD(&info->swaplist); 1425 1426 switch (mode & S_IFMT) { 1427 default: 1428 inode->i_op = &shmem_special_inode_operations; 1429 init_special_inode(inode, mode, dev); 1430 break; 1431 case S_IFREG: 1432 inode->i_op = &shmem_inode_operations; 1433 inode->i_fop = &shmem_file_operations; 1434 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1435 &sbinfo->policy_nodes); 1436 break; 1437 case S_IFDIR: 1438 inc_nlink(inode); 1439 /* Some things misbehave if size == 0 on a directory */ 1440 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1441 inode->i_op = &shmem_dir_inode_operations; 1442 inode->i_fop = &simple_dir_operations; 1443 break; 1444 case S_IFLNK: 1445 /* 1446 * Must not load anything in the rbtree, 1447 * mpol_free_shared_policy will not be called. 1448 */ 1449 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1450 NULL); 1451 break; 1452 } 1453 } else if (sbinfo->max_inodes) { 1454 spin_lock(&sbinfo->stat_lock); 1455 sbinfo->free_inodes++; 1456 spin_unlock(&sbinfo->stat_lock); 1457 } 1458 return inode; 1459 } 1460 1461 #ifdef CONFIG_TMPFS 1462 static const struct inode_operations shmem_symlink_inode_operations; 1463 static const struct inode_operations shmem_symlink_inline_operations; 1464 1465 /* 1466 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1467 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1468 * below the loop driver, in the generic fashion that many filesystems support. 1469 */ 1470 static int shmem_readpage(struct file *file, struct page *page) 1471 { 1472 struct inode *inode = page->mapping->host; 1473 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1474 unlock_page(page); 1475 return error; 1476 } 1477 1478 static int 1479 shmem_write_begin(struct file *file, struct address_space *mapping, 1480 loff_t pos, unsigned len, unsigned flags, 1481 struct page **pagep, void **fsdata) 1482 { 1483 struct inode *inode = mapping->host; 1484 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1485 *pagep = NULL; 1486 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1487 } 1488 1489 static int 1490 shmem_write_end(struct file *file, struct address_space *mapping, 1491 loff_t pos, unsigned len, unsigned copied, 1492 struct page *page, void *fsdata) 1493 { 1494 struct inode *inode = mapping->host; 1495 1496 set_page_dirty(page); 1497 page_cache_release(page); 1498 1499 if (pos+copied > inode->i_size) 1500 i_size_write(inode, pos+copied); 1501 1502 return copied; 1503 } 1504 1505 static ssize_t 1506 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1507 { 1508 struct inode *inode = file->f_path.dentry->d_inode; 1509 loff_t pos; 1510 unsigned long written; 1511 ssize_t err; 1512 1513 if ((ssize_t) count < 0) 1514 return -EINVAL; 1515 1516 if (!access_ok(VERIFY_READ, buf, count)) 1517 return -EFAULT; 1518 1519 mutex_lock(&inode->i_mutex); 1520 1521 pos = *ppos; 1522 written = 0; 1523 1524 err = generic_write_checks(file, &pos, &count, 0); 1525 if (err || !count) 1526 goto out; 1527 1528 err = remove_suid(file->f_path.dentry); 1529 if (err) 1530 goto out; 1531 1532 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1533 1534 do { 1535 struct page *page = NULL; 1536 unsigned long bytes, index, offset; 1537 char *kaddr; 1538 int left; 1539 1540 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1541 index = pos >> PAGE_CACHE_SHIFT; 1542 bytes = PAGE_CACHE_SIZE - offset; 1543 if (bytes > count) 1544 bytes = count; 1545 1546 /* 1547 * We don't hold page lock across copy from user - 1548 * what would it guard against? - so no deadlock here. 1549 * But it still may be a good idea to prefault below. 1550 */ 1551 1552 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1553 if (err) 1554 break; 1555 1556 left = bytes; 1557 if (PageHighMem(page)) { 1558 volatile unsigned char dummy; 1559 __get_user(dummy, buf); 1560 __get_user(dummy, buf + bytes - 1); 1561 1562 kaddr = kmap_atomic(page, KM_USER0); 1563 left = __copy_from_user_inatomic(kaddr + offset, 1564 buf, bytes); 1565 kunmap_atomic(kaddr, KM_USER0); 1566 } 1567 if (left) { 1568 kaddr = kmap(page); 1569 left = __copy_from_user(kaddr + offset, buf, bytes); 1570 kunmap(page); 1571 } 1572 1573 written += bytes; 1574 count -= bytes; 1575 pos += bytes; 1576 buf += bytes; 1577 if (pos > inode->i_size) 1578 i_size_write(inode, pos); 1579 1580 flush_dcache_page(page); 1581 set_page_dirty(page); 1582 mark_page_accessed(page); 1583 page_cache_release(page); 1584 1585 if (left) { 1586 pos -= left; 1587 written -= left; 1588 err = -EFAULT; 1589 break; 1590 } 1591 1592 /* 1593 * Our dirty pages are not counted in nr_dirty, 1594 * and we do not attempt to balance dirty pages. 1595 */ 1596 1597 cond_resched(); 1598 } while (count); 1599 1600 *ppos = pos; 1601 if (written) 1602 err = written; 1603 out: 1604 mutex_unlock(&inode->i_mutex); 1605 return err; 1606 } 1607 1608 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1609 { 1610 struct inode *inode = filp->f_path.dentry->d_inode; 1611 struct address_space *mapping = inode->i_mapping; 1612 unsigned long index, offset; 1613 1614 index = *ppos >> PAGE_CACHE_SHIFT; 1615 offset = *ppos & ~PAGE_CACHE_MASK; 1616 1617 for (;;) { 1618 struct page *page = NULL; 1619 unsigned long end_index, nr, ret; 1620 loff_t i_size = i_size_read(inode); 1621 1622 end_index = i_size >> PAGE_CACHE_SHIFT; 1623 if (index > end_index) 1624 break; 1625 if (index == end_index) { 1626 nr = i_size & ~PAGE_CACHE_MASK; 1627 if (nr <= offset) 1628 break; 1629 } 1630 1631 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1632 if (desc->error) { 1633 if (desc->error == -EINVAL) 1634 desc->error = 0; 1635 break; 1636 } 1637 1638 /* 1639 * We must evaluate after, since reads (unlike writes) 1640 * are called without i_mutex protection against truncate 1641 */ 1642 nr = PAGE_CACHE_SIZE; 1643 i_size = i_size_read(inode); 1644 end_index = i_size >> PAGE_CACHE_SHIFT; 1645 if (index == end_index) { 1646 nr = i_size & ~PAGE_CACHE_MASK; 1647 if (nr <= offset) { 1648 if (page) 1649 page_cache_release(page); 1650 break; 1651 } 1652 } 1653 nr -= offset; 1654 1655 if (page) { 1656 /* 1657 * If users can be writing to this page using arbitrary 1658 * virtual addresses, take care about potential aliasing 1659 * before reading the page on the kernel side. 1660 */ 1661 if (mapping_writably_mapped(mapping)) 1662 flush_dcache_page(page); 1663 /* 1664 * Mark the page accessed if we read the beginning. 1665 */ 1666 if (!offset) 1667 mark_page_accessed(page); 1668 } else { 1669 page = ZERO_PAGE(0); 1670 page_cache_get(page); 1671 } 1672 1673 /* 1674 * Ok, we have the page, and it's up-to-date, so 1675 * now we can copy it to user space... 1676 * 1677 * The actor routine returns how many bytes were actually used.. 1678 * NOTE! This may not be the same as how much of a user buffer 1679 * we filled up (we may be padding etc), so we can only update 1680 * "pos" here (the actor routine has to update the user buffer 1681 * pointers and the remaining count). 1682 */ 1683 ret = actor(desc, page, offset, nr); 1684 offset += ret; 1685 index += offset >> PAGE_CACHE_SHIFT; 1686 offset &= ~PAGE_CACHE_MASK; 1687 1688 page_cache_release(page); 1689 if (ret != nr || !desc->count) 1690 break; 1691 1692 cond_resched(); 1693 } 1694 1695 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1696 file_accessed(filp); 1697 } 1698 1699 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1700 { 1701 read_descriptor_t desc; 1702 1703 if ((ssize_t) count < 0) 1704 return -EINVAL; 1705 if (!access_ok(VERIFY_WRITE, buf, count)) 1706 return -EFAULT; 1707 if (!count) 1708 return 0; 1709 1710 desc.written = 0; 1711 desc.count = count; 1712 desc.arg.buf = buf; 1713 desc.error = 0; 1714 1715 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1716 if (desc.written) 1717 return desc.written; 1718 return desc.error; 1719 } 1720 1721 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1722 { 1723 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1724 1725 buf->f_type = TMPFS_MAGIC; 1726 buf->f_bsize = PAGE_CACHE_SIZE; 1727 buf->f_namelen = NAME_MAX; 1728 spin_lock(&sbinfo->stat_lock); 1729 if (sbinfo->max_blocks) { 1730 buf->f_blocks = sbinfo->max_blocks; 1731 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1732 } 1733 if (sbinfo->max_inodes) { 1734 buf->f_files = sbinfo->max_inodes; 1735 buf->f_ffree = sbinfo->free_inodes; 1736 } 1737 /* else leave those fields 0 like simple_statfs */ 1738 spin_unlock(&sbinfo->stat_lock); 1739 return 0; 1740 } 1741 1742 /* 1743 * File creation. Allocate an inode, and we're done.. 1744 */ 1745 static int 1746 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1747 { 1748 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1749 int error = -ENOSPC; 1750 1751 if (inode) { 1752 error = security_inode_init_security(inode, dir, NULL, NULL, 1753 NULL); 1754 if (error) { 1755 if (error != -EOPNOTSUPP) { 1756 iput(inode); 1757 return error; 1758 } 1759 } 1760 error = shmem_acl_init(inode, dir); 1761 if (error) { 1762 iput(inode); 1763 return error; 1764 } 1765 if (dir->i_mode & S_ISGID) { 1766 inode->i_gid = dir->i_gid; 1767 if (S_ISDIR(mode)) 1768 inode->i_mode |= S_ISGID; 1769 } 1770 dir->i_size += BOGO_DIRENT_SIZE; 1771 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1772 d_instantiate(dentry, inode); 1773 dget(dentry); /* Extra count - pin the dentry in core */ 1774 } 1775 return error; 1776 } 1777 1778 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1779 { 1780 int error; 1781 1782 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1783 return error; 1784 inc_nlink(dir); 1785 return 0; 1786 } 1787 1788 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1789 struct nameidata *nd) 1790 { 1791 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1792 } 1793 1794 /* 1795 * Link a file.. 1796 */ 1797 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1798 { 1799 struct inode *inode = old_dentry->d_inode; 1800 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1801 1802 /* 1803 * No ordinary (disk based) filesystem counts links as inodes; 1804 * but each new link needs a new dentry, pinning lowmem, and 1805 * tmpfs dentries cannot be pruned until they are unlinked. 1806 */ 1807 if (sbinfo->max_inodes) { 1808 spin_lock(&sbinfo->stat_lock); 1809 if (!sbinfo->free_inodes) { 1810 spin_unlock(&sbinfo->stat_lock); 1811 return -ENOSPC; 1812 } 1813 sbinfo->free_inodes--; 1814 spin_unlock(&sbinfo->stat_lock); 1815 } 1816 1817 dir->i_size += BOGO_DIRENT_SIZE; 1818 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1819 inc_nlink(inode); 1820 atomic_inc(&inode->i_count); /* New dentry reference */ 1821 dget(dentry); /* Extra pinning count for the created dentry */ 1822 d_instantiate(dentry, inode); 1823 return 0; 1824 } 1825 1826 static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1827 { 1828 struct inode *inode = dentry->d_inode; 1829 1830 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1831 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1832 if (sbinfo->max_inodes) { 1833 spin_lock(&sbinfo->stat_lock); 1834 sbinfo->free_inodes++; 1835 spin_unlock(&sbinfo->stat_lock); 1836 } 1837 } 1838 1839 dir->i_size -= BOGO_DIRENT_SIZE; 1840 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1841 drop_nlink(inode); 1842 dput(dentry); /* Undo the count from "create" - this does all the work */ 1843 return 0; 1844 } 1845 1846 static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1847 { 1848 if (!simple_empty(dentry)) 1849 return -ENOTEMPTY; 1850 1851 drop_nlink(dentry->d_inode); 1852 drop_nlink(dir); 1853 return shmem_unlink(dir, dentry); 1854 } 1855 1856 /* 1857 * The VFS layer already does all the dentry stuff for rename, 1858 * we just have to decrement the usage count for the target if 1859 * it exists so that the VFS layer correctly free's it when it 1860 * gets overwritten. 1861 */ 1862 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1863 { 1864 struct inode *inode = old_dentry->d_inode; 1865 int they_are_dirs = S_ISDIR(inode->i_mode); 1866 1867 if (!simple_empty(new_dentry)) 1868 return -ENOTEMPTY; 1869 1870 if (new_dentry->d_inode) { 1871 (void) shmem_unlink(new_dir, new_dentry); 1872 if (they_are_dirs) 1873 drop_nlink(old_dir); 1874 } else if (they_are_dirs) { 1875 drop_nlink(old_dir); 1876 inc_nlink(new_dir); 1877 } 1878 1879 old_dir->i_size -= BOGO_DIRENT_SIZE; 1880 new_dir->i_size += BOGO_DIRENT_SIZE; 1881 old_dir->i_ctime = old_dir->i_mtime = 1882 new_dir->i_ctime = new_dir->i_mtime = 1883 inode->i_ctime = CURRENT_TIME; 1884 return 0; 1885 } 1886 1887 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1888 { 1889 int error; 1890 int len; 1891 struct inode *inode; 1892 struct page *page = NULL; 1893 char *kaddr; 1894 struct shmem_inode_info *info; 1895 1896 len = strlen(symname) + 1; 1897 if (len > PAGE_CACHE_SIZE) 1898 return -ENAMETOOLONG; 1899 1900 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1901 if (!inode) 1902 return -ENOSPC; 1903 1904 error = security_inode_init_security(inode, dir, NULL, NULL, 1905 NULL); 1906 if (error) { 1907 if (error != -EOPNOTSUPP) { 1908 iput(inode); 1909 return error; 1910 } 1911 error = 0; 1912 } 1913 1914 info = SHMEM_I(inode); 1915 inode->i_size = len-1; 1916 if (len <= (char *)inode - (char *)info) { 1917 /* do it inline */ 1918 memcpy(info, symname, len); 1919 inode->i_op = &shmem_symlink_inline_operations; 1920 } else { 1921 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1922 if (error) { 1923 iput(inode); 1924 return error; 1925 } 1926 inode->i_op = &shmem_symlink_inode_operations; 1927 kaddr = kmap_atomic(page, KM_USER0); 1928 memcpy(kaddr, symname, len); 1929 kunmap_atomic(kaddr, KM_USER0); 1930 set_page_dirty(page); 1931 page_cache_release(page); 1932 } 1933 if (dir->i_mode & S_ISGID) 1934 inode->i_gid = dir->i_gid; 1935 dir->i_size += BOGO_DIRENT_SIZE; 1936 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1937 d_instantiate(dentry, inode); 1938 dget(dentry); 1939 return 0; 1940 } 1941 1942 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1943 { 1944 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1945 return NULL; 1946 } 1947 1948 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1949 { 1950 struct page *page = NULL; 1951 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1952 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1953 return page; 1954 } 1955 1956 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1957 { 1958 if (!IS_ERR(nd_get_link(nd))) { 1959 struct page *page = cookie; 1960 kunmap(page); 1961 mark_page_accessed(page); 1962 page_cache_release(page); 1963 } 1964 } 1965 1966 static const struct inode_operations shmem_symlink_inline_operations = { 1967 .readlink = generic_readlink, 1968 .follow_link = shmem_follow_link_inline, 1969 }; 1970 1971 static const struct inode_operations shmem_symlink_inode_operations = { 1972 .truncate = shmem_truncate, 1973 .readlink = generic_readlink, 1974 .follow_link = shmem_follow_link, 1975 .put_link = shmem_put_link, 1976 }; 1977 1978 #ifdef CONFIG_TMPFS_POSIX_ACL 1979 /** 1980 * Superblocks without xattr inode operations will get security.* xattr 1981 * support from the VFS "for free". As soon as we have any other xattrs 1982 * like ACLs, we also need to implement the security.* handlers at 1983 * filesystem level, though. 1984 */ 1985 1986 static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1987 size_t list_len, const char *name, 1988 size_t name_len) 1989 { 1990 return security_inode_listsecurity(inode, list, list_len); 1991 } 1992 1993 static int shmem_xattr_security_get(struct inode *inode, const char *name, 1994 void *buffer, size_t size) 1995 { 1996 if (strcmp(name, "") == 0) 1997 return -EINVAL; 1998 return security_inode_getsecurity(inode, name, buffer, size, 1999 -EOPNOTSUPP); 2000 } 2001 2002 static int shmem_xattr_security_set(struct inode *inode, const char *name, 2003 const void *value, size_t size, int flags) 2004 { 2005 if (strcmp(name, "") == 0) 2006 return -EINVAL; 2007 return security_inode_setsecurity(inode, name, value, size, flags); 2008 } 2009 2010 static struct xattr_handler shmem_xattr_security_handler = { 2011 .prefix = XATTR_SECURITY_PREFIX, 2012 .list = shmem_xattr_security_list, 2013 .get = shmem_xattr_security_get, 2014 .set = shmem_xattr_security_set, 2015 }; 2016 2017 static struct xattr_handler *shmem_xattr_handlers[] = { 2018 &shmem_xattr_acl_access_handler, 2019 &shmem_xattr_acl_default_handler, 2020 &shmem_xattr_security_handler, 2021 NULL 2022 }; 2023 #endif 2024 2025 static struct dentry *shmem_get_parent(struct dentry *child) 2026 { 2027 return ERR_PTR(-ESTALE); 2028 } 2029 2030 static int shmem_match(struct inode *ino, void *vfh) 2031 { 2032 __u32 *fh = vfh; 2033 __u64 inum = fh[2]; 2034 inum = (inum << 32) | fh[1]; 2035 return ino->i_ino == inum && fh[0] == ino->i_generation; 2036 } 2037 2038 static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2039 struct fid *fid, int fh_len, int fh_type) 2040 { 2041 struct inode *inode; 2042 struct dentry *dentry = NULL; 2043 u64 inum = fid->raw[2]; 2044 inum = (inum << 32) | fid->raw[1]; 2045 2046 if (fh_len < 3) 2047 return NULL; 2048 2049 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2050 shmem_match, fid->raw); 2051 if (inode) { 2052 dentry = d_find_alias(inode); 2053 iput(inode); 2054 } 2055 2056 return dentry; 2057 } 2058 2059 static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2060 int connectable) 2061 { 2062 struct inode *inode = dentry->d_inode; 2063 2064 if (*len < 3) 2065 return 255; 2066 2067 if (hlist_unhashed(&inode->i_hash)) { 2068 /* Unfortunately insert_inode_hash is not idempotent, 2069 * so as we hash inodes here rather than at creation 2070 * time, we need a lock to ensure we only try 2071 * to do it once 2072 */ 2073 static DEFINE_SPINLOCK(lock); 2074 spin_lock(&lock); 2075 if (hlist_unhashed(&inode->i_hash)) 2076 __insert_inode_hash(inode, 2077 inode->i_ino + inode->i_generation); 2078 spin_unlock(&lock); 2079 } 2080 2081 fh[0] = inode->i_generation; 2082 fh[1] = inode->i_ino; 2083 fh[2] = ((__u64)inode->i_ino) >> 32; 2084 2085 *len = 3; 2086 return 1; 2087 } 2088 2089 static const struct export_operations shmem_export_ops = { 2090 .get_parent = shmem_get_parent, 2091 .encode_fh = shmem_encode_fh, 2092 .fh_to_dentry = shmem_fh_to_dentry, 2093 }; 2094 2095 static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2096 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2097 int *policy, nodemask_t *policy_nodes) 2098 { 2099 char *this_char, *value, *rest; 2100 2101 while (options != NULL) { 2102 this_char = options; 2103 for (;;) { 2104 /* 2105 * NUL-terminate this option: unfortunately, 2106 * mount options form a comma-separated list, 2107 * but mpol's nodelist may also contain commas. 2108 */ 2109 options = strchr(options, ','); 2110 if (options == NULL) 2111 break; 2112 options++; 2113 if (!isdigit(*options)) { 2114 options[-1] = '\0'; 2115 break; 2116 } 2117 } 2118 if (!*this_char) 2119 continue; 2120 if ((value = strchr(this_char,'=')) != NULL) { 2121 *value++ = 0; 2122 } else { 2123 printk(KERN_ERR 2124 "tmpfs: No value for mount option '%s'\n", 2125 this_char); 2126 return 1; 2127 } 2128 2129 if (!strcmp(this_char,"size")) { 2130 unsigned long long size; 2131 size = memparse(value,&rest); 2132 if (*rest == '%') { 2133 size <<= PAGE_SHIFT; 2134 size *= totalram_pages; 2135 do_div(size, 100); 2136 rest++; 2137 } 2138 if (*rest) 2139 goto bad_val; 2140 *blocks = size >> PAGE_CACHE_SHIFT; 2141 } else if (!strcmp(this_char,"nr_blocks")) { 2142 *blocks = memparse(value,&rest); 2143 if (*rest) 2144 goto bad_val; 2145 } else if (!strcmp(this_char,"nr_inodes")) { 2146 *inodes = memparse(value,&rest); 2147 if (*rest) 2148 goto bad_val; 2149 } else if (!strcmp(this_char,"mode")) { 2150 if (!mode) 2151 continue; 2152 *mode = simple_strtoul(value,&rest,8); 2153 if (*rest) 2154 goto bad_val; 2155 } else if (!strcmp(this_char,"uid")) { 2156 if (!uid) 2157 continue; 2158 *uid = simple_strtoul(value,&rest,0); 2159 if (*rest) 2160 goto bad_val; 2161 } else if (!strcmp(this_char,"gid")) { 2162 if (!gid) 2163 continue; 2164 *gid = simple_strtoul(value,&rest,0); 2165 if (*rest) 2166 goto bad_val; 2167 } else if (!strcmp(this_char,"mpol")) { 2168 if (shmem_parse_mpol(value,policy,policy_nodes)) 2169 goto bad_val; 2170 } else { 2171 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2172 this_char); 2173 return 1; 2174 } 2175 } 2176 return 0; 2177 2178 bad_val: 2179 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2180 value, this_char); 2181 return 1; 2182 2183 } 2184 2185 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2186 { 2187 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2188 unsigned long max_blocks = sbinfo->max_blocks; 2189 unsigned long max_inodes = sbinfo->max_inodes; 2190 int policy = sbinfo->policy; 2191 nodemask_t policy_nodes = sbinfo->policy_nodes; 2192 unsigned long blocks; 2193 unsigned long inodes; 2194 int error = -EINVAL; 2195 2196 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2197 &max_inodes, &policy, &policy_nodes)) 2198 return error; 2199 2200 spin_lock(&sbinfo->stat_lock); 2201 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2202 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2203 if (max_blocks < blocks) 2204 goto out; 2205 if (max_inodes < inodes) 2206 goto out; 2207 /* 2208 * Those tests also disallow limited->unlimited while any are in 2209 * use, so i_blocks will always be zero when max_blocks is zero; 2210 * but we must separately disallow unlimited->limited, because 2211 * in that case we have no record of how much is already in use. 2212 */ 2213 if (max_blocks && !sbinfo->max_blocks) 2214 goto out; 2215 if (max_inodes && !sbinfo->max_inodes) 2216 goto out; 2217 2218 error = 0; 2219 sbinfo->max_blocks = max_blocks; 2220 sbinfo->free_blocks = max_blocks - blocks; 2221 sbinfo->max_inodes = max_inodes; 2222 sbinfo->free_inodes = max_inodes - inodes; 2223 sbinfo->policy = policy; 2224 sbinfo->policy_nodes = policy_nodes; 2225 out: 2226 spin_unlock(&sbinfo->stat_lock); 2227 return error; 2228 } 2229 #endif 2230 2231 static void shmem_put_super(struct super_block *sb) 2232 { 2233 kfree(sb->s_fs_info); 2234 sb->s_fs_info = NULL; 2235 } 2236 2237 static int shmem_fill_super(struct super_block *sb, 2238 void *data, int silent) 2239 { 2240 struct inode *inode; 2241 struct dentry *root; 2242 int mode = S_IRWXUGO | S_ISVTX; 2243 uid_t uid = current->fsuid; 2244 gid_t gid = current->fsgid; 2245 int err = -ENOMEM; 2246 struct shmem_sb_info *sbinfo; 2247 unsigned long blocks = 0; 2248 unsigned long inodes = 0; 2249 int policy = MPOL_DEFAULT; 2250 nodemask_t policy_nodes = node_states[N_HIGH_MEMORY]; 2251 2252 #ifdef CONFIG_TMPFS 2253 /* 2254 * Per default we only allow half of the physical ram per 2255 * tmpfs instance, limiting inodes to one per page of lowmem; 2256 * but the internal instance is left unlimited. 2257 */ 2258 if (!(sb->s_flags & MS_NOUSER)) { 2259 blocks = totalram_pages / 2; 2260 inodes = totalram_pages - totalhigh_pages; 2261 if (inodes > blocks) 2262 inodes = blocks; 2263 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2264 &inodes, &policy, &policy_nodes)) 2265 return -EINVAL; 2266 } 2267 sb->s_export_op = &shmem_export_ops; 2268 #else 2269 sb->s_flags |= MS_NOUSER; 2270 #endif 2271 2272 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2273 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2274 L1_CACHE_BYTES), GFP_KERNEL); 2275 if (!sbinfo) 2276 return -ENOMEM; 2277 2278 spin_lock_init(&sbinfo->stat_lock); 2279 sbinfo->max_blocks = blocks; 2280 sbinfo->free_blocks = blocks; 2281 sbinfo->max_inodes = inodes; 2282 sbinfo->free_inodes = inodes; 2283 sbinfo->policy = policy; 2284 sbinfo->policy_nodes = policy_nodes; 2285 2286 sb->s_fs_info = sbinfo; 2287 sb->s_maxbytes = SHMEM_MAX_BYTES; 2288 sb->s_blocksize = PAGE_CACHE_SIZE; 2289 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2290 sb->s_magic = TMPFS_MAGIC; 2291 sb->s_op = &shmem_ops; 2292 sb->s_time_gran = 1; 2293 #ifdef CONFIG_TMPFS_POSIX_ACL 2294 sb->s_xattr = shmem_xattr_handlers; 2295 sb->s_flags |= MS_POSIXACL; 2296 #endif 2297 2298 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2299 if (!inode) 2300 goto failed; 2301 inode->i_uid = uid; 2302 inode->i_gid = gid; 2303 root = d_alloc_root(inode); 2304 if (!root) 2305 goto failed_iput; 2306 sb->s_root = root; 2307 return 0; 2308 2309 failed_iput: 2310 iput(inode); 2311 failed: 2312 shmem_put_super(sb); 2313 return err; 2314 } 2315 2316 static struct kmem_cache *shmem_inode_cachep; 2317 2318 static struct inode *shmem_alloc_inode(struct super_block *sb) 2319 { 2320 struct shmem_inode_info *p; 2321 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2322 if (!p) 2323 return NULL; 2324 return &p->vfs_inode; 2325 } 2326 2327 static void shmem_destroy_inode(struct inode *inode) 2328 { 2329 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2330 /* only struct inode is valid if it's an inline symlink */ 2331 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2332 } 2333 shmem_acl_destroy_inode(inode); 2334 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2335 } 2336 2337 static void init_once(struct kmem_cache *cachep, void *foo) 2338 { 2339 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2340 2341 inode_init_once(&p->vfs_inode); 2342 #ifdef CONFIG_TMPFS_POSIX_ACL 2343 p->i_acl = NULL; 2344 p->i_default_acl = NULL; 2345 #endif 2346 } 2347 2348 static int init_inodecache(void) 2349 { 2350 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2351 sizeof(struct shmem_inode_info), 2352 0, SLAB_PANIC, init_once); 2353 return 0; 2354 } 2355 2356 static void destroy_inodecache(void) 2357 { 2358 kmem_cache_destroy(shmem_inode_cachep); 2359 } 2360 2361 static const struct address_space_operations shmem_aops = { 2362 .writepage = shmem_writepage, 2363 .set_page_dirty = __set_page_dirty_no_writeback, 2364 #ifdef CONFIG_TMPFS 2365 .readpage = shmem_readpage, 2366 .write_begin = shmem_write_begin, 2367 .write_end = shmem_write_end, 2368 #endif 2369 .migratepage = migrate_page, 2370 }; 2371 2372 static const struct file_operations shmem_file_operations = { 2373 .mmap = shmem_mmap, 2374 #ifdef CONFIG_TMPFS 2375 .llseek = generic_file_llseek, 2376 .read = shmem_file_read, 2377 .write = shmem_file_write, 2378 .fsync = simple_sync_file, 2379 .splice_read = generic_file_splice_read, 2380 .splice_write = generic_file_splice_write, 2381 #endif 2382 }; 2383 2384 static const struct inode_operations shmem_inode_operations = { 2385 .truncate = shmem_truncate, 2386 .setattr = shmem_notify_change, 2387 .truncate_range = shmem_truncate_range, 2388 #ifdef CONFIG_TMPFS_POSIX_ACL 2389 .setxattr = generic_setxattr, 2390 .getxattr = generic_getxattr, 2391 .listxattr = generic_listxattr, 2392 .removexattr = generic_removexattr, 2393 .permission = shmem_permission, 2394 #endif 2395 2396 }; 2397 2398 static const struct inode_operations shmem_dir_inode_operations = { 2399 #ifdef CONFIG_TMPFS 2400 .create = shmem_create, 2401 .lookup = simple_lookup, 2402 .link = shmem_link, 2403 .unlink = shmem_unlink, 2404 .symlink = shmem_symlink, 2405 .mkdir = shmem_mkdir, 2406 .rmdir = shmem_rmdir, 2407 .mknod = shmem_mknod, 2408 .rename = shmem_rename, 2409 #endif 2410 #ifdef CONFIG_TMPFS_POSIX_ACL 2411 .setattr = shmem_notify_change, 2412 .setxattr = generic_setxattr, 2413 .getxattr = generic_getxattr, 2414 .listxattr = generic_listxattr, 2415 .removexattr = generic_removexattr, 2416 .permission = shmem_permission, 2417 #endif 2418 }; 2419 2420 static const struct inode_operations shmem_special_inode_operations = { 2421 #ifdef CONFIG_TMPFS_POSIX_ACL 2422 .setattr = shmem_notify_change, 2423 .setxattr = generic_setxattr, 2424 .getxattr = generic_getxattr, 2425 .listxattr = generic_listxattr, 2426 .removexattr = generic_removexattr, 2427 .permission = shmem_permission, 2428 #endif 2429 }; 2430 2431 static const struct super_operations shmem_ops = { 2432 .alloc_inode = shmem_alloc_inode, 2433 .destroy_inode = shmem_destroy_inode, 2434 #ifdef CONFIG_TMPFS 2435 .statfs = shmem_statfs, 2436 .remount_fs = shmem_remount_fs, 2437 #endif 2438 .delete_inode = shmem_delete_inode, 2439 .drop_inode = generic_delete_inode, 2440 .put_super = shmem_put_super, 2441 }; 2442 2443 static struct vm_operations_struct shmem_vm_ops = { 2444 .fault = shmem_fault, 2445 #ifdef CONFIG_NUMA 2446 .set_policy = shmem_set_policy, 2447 .get_policy = shmem_get_policy, 2448 #endif 2449 }; 2450 2451 2452 static int shmem_get_sb(struct file_system_type *fs_type, 2453 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2454 { 2455 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2456 } 2457 2458 static struct file_system_type tmpfs_fs_type = { 2459 .owner = THIS_MODULE, 2460 .name = "tmpfs", 2461 .get_sb = shmem_get_sb, 2462 .kill_sb = kill_litter_super, 2463 }; 2464 static struct vfsmount *shm_mnt; 2465 2466 static int __init init_tmpfs(void) 2467 { 2468 int error; 2469 2470 error = bdi_init(&shmem_backing_dev_info); 2471 if (error) 2472 goto out4; 2473 2474 error = init_inodecache(); 2475 if (error) 2476 goto out3; 2477 2478 error = register_filesystem(&tmpfs_fs_type); 2479 if (error) { 2480 printk(KERN_ERR "Could not register tmpfs\n"); 2481 goto out2; 2482 } 2483 2484 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2485 tmpfs_fs_type.name, NULL); 2486 if (IS_ERR(shm_mnt)) { 2487 error = PTR_ERR(shm_mnt); 2488 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2489 goto out1; 2490 } 2491 return 0; 2492 2493 out1: 2494 unregister_filesystem(&tmpfs_fs_type); 2495 out2: 2496 destroy_inodecache(); 2497 out3: 2498 bdi_destroy(&shmem_backing_dev_info); 2499 out4: 2500 shm_mnt = ERR_PTR(error); 2501 return error; 2502 } 2503 module_init(init_tmpfs) 2504 2505 /* 2506 * shmem_file_setup - get an unlinked file living in tmpfs 2507 * 2508 * @name: name for dentry (to be seen in /proc/<pid>/maps 2509 * @size: size to be set for the file 2510 * 2511 */ 2512 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2513 { 2514 int error; 2515 struct file *file; 2516 struct inode *inode; 2517 struct dentry *dentry, *root; 2518 struct qstr this; 2519 2520 if (IS_ERR(shm_mnt)) 2521 return (void *)shm_mnt; 2522 2523 if (size < 0 || size > SHMEM_MAX_BYTES) 2524 return ERR_PTR(-EINVAL); 2525 2526 if (shmem_acct_size(flags, size)) 2527 return ERR_PTR(-ENOMEM); 2528 2529 error = -ENOMEM; 2530 this.name = name; 2531 this.len = strlen(name); 2532 this.hash = 0; /* will go */ 2533 root = shm_mnt->mnt_root; 2534 dentry = d_alloc(root, &this); 2535 if (!dentry) 2536 goto put_memory; 2537 2538 error = -ENFILE; 2539 file = get_empty_filp(); 2540 if (!file) 2541 goto put_dentry; 2542 2543 error = -ENOSPC; 2544 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2545 if (!inode) 2546 goto close_file; 2547 2548 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2549 d_instantiate(dentry, inode); 2550 inode->i_size = size; 2551 inode->i_nlink = 0; /* It is unlinked */ 2552 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ, 2553 &shmem_file_operations); 2554 return file; 2555 2556 close_file: 2557 put_filp(file); 2558 put_dentry: 2559 dput(dentry); 2560 put_memory: 2561 shmem_unacct_size(flags, size); 2562 return ERR_PTR(error); 2563 } 2564 2565 /* 2566 * shmem_zero_setup - setup a shared anonymous mapping 2567 * 2568 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2569 */ 2570 int shmem_zero_setup(struct vm_area_struct *vma) 2571 { 2572 struct file *file; 2573 loff_t size = vma->vm_end - vma->vm_start; 2574 2575 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2576 if (IS_ERR(file)) 2577 return PTR_ERR(file); 2578 2579 if (vma->vm_file) 2580 fput(vma->vm_file); 2581 vma->vm_file = file; 2582 vma->vm_ops = &shmem_vm_ops; 2583 return 0; 2584 } 2585