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/generic_acl.h> 31 #include <linux/mm.h> 32 #include <linux/mman.h> 33 #include <linux/file.h> 34 #include <linux/swap.h> 35 #include <linux/pagemap.h> 36 #include <linux/string.h> 37 #include <linux/slab.h> 38 #include <linux/backing-dev.h> 39 #include <linux/shmem_fs.h> 40 #include <linux/mount.h> 41 #include <linux/writeback.h> 42 #include <linux/vfs.h> 43 #include <linux/blkdev.h> 44 #include <linux/security.h> 45 #include <linux/swapops.h> 46 #include <linux/mempolicy.h> 47 #include <linux/namei.h> 48 #include <linux/ctype.h> 49 #include <linux/migrate.h> 50 #include <linux/highmem.h> 51 #include <linux/backing-dev.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 }; 86 87 static int shmem_getpage(struct inode *inode, unsigned long idx, 88 struct page **pagep, enum sgp_type sgp, int *type); 89 90 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 91 { 92 /* 93 * The above definition of ENTRIES_PER_PAGE, and the use of 94 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 95 * might be reconsidered if it ever diverges from PAGE_SIZE. 96 */ 97 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); 98 } 99 100 static inline void shmem_dir_free(struct page *page) 101 { 102 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 103 } 104 105 static struct page **shmem_dir_map(struct page *page) 106 { 107 return (struct page **)kmap_atomic(page, KM_USER0); 108 } 109 110 static inline void shmem_dir_unmap(struct page **dir) 111 { 112 kunmap_atomic(dir, KM_USER0); 113 } 114 115 static swp_entry_t *shmem_swp_map(struct page *page) 116 { 117 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 118 } 119 120 static inline void shmem_swp_balance_unmap(void) 121 { 122 /* 123 * When passing a pointer to an i_direct entry, to code which 124 * also handles indirect entries and so will shmem_swp_unmap, 125 * we must arrange for the preempt count to remain in balance. 126 * What kmap_atomic of a lowmem page does depends on config 127 * and architecture, so pretend to kmap_atomic some lowmem page. 128 */ 129 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 130 } 131 132 static inline void shmem_swp_unmap(swp_entry_t *entry) 133 { 134 kunmap_atomic(entry, KM_USER1); 135 } 136 137 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 138 { 139 return sb->s_fs_info; 140 } 141 142 /* 143 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 144 * for shared memory and for shared anonymous (/dev/zero) mappings 145 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 146 * consistent with the pre-accounting of private mappings ... 147 */ 148 static inline int shmem_acct_size(unsigned long flags, loff_t size) 149 { 150 return (flags & VM_ACCOUNT)? 151 security_vm_enough_memory(VM_ACCT(size)): 0; 152 } 153 154 static inline void shmem_unacct_size(unsigned long flags, loff_t size) 155 { 156 if (flags & VM_ACCOUNT) 157 vm_unacct_memory(VM_ACCT(size)); 158 } 159 160 /* 161 * ... whereas tmpfs objects are accounted incrementally as 162 * pages are allocated, in order to allow huge sparse files. 163 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 164 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 165 */ 166 static inline int shmem_acct_block(unsigned long flags) 167 { 168 return (flags & VM_ACCOUNT)? 169 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 170 } 171 172 static inline void shmem_unacct_blocks(unsigned long flags, long pages) 173 { 174 if (!(flags & VM_ACCOUNT)) 175 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 176 } 177 178 static const struct super_operations shmem_ops; 179 static const struct address_space_operations shmem_aops; 180 static const struct file_operations shmem_file_operations; 181 static const struct inode_operations shmem_inode_operations; 182 static const struct inode_operations shmem_dir_inode_operations; 183 static const struct inode_operations shmem_special_inode_operations; 184 static struct vm_operations_struct shmem_vm_ops; 185 186 static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 187 .ra_pages = 0, /* No readahead */ 188 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 189 .unplug_io_fn = default_unplug_io_fn, 190 }; 191 192 static LIST_HEAD(shmem_swaplist); 193 static DEFINE_SPINLOCK(shmem_swaplist_lock); 194 195 static void shmem_free_blocks(struct inode *inode, long pages) 196 { 197 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 198 if (sbinfo->max_blocks) { 199 spin_lock(&sbinfo->stat_lock); 200 sbinfo->free_blocks += pages; 201 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 202 spin_unlock(&sbinfo->stat_lock); 203 } 204 } 205 206 /* 207 * shmem_recalc_inode - recalculate the size of an inode 208 * 209 * @inode: inode to recalc 210 * 211 * We have to calculate the free blocks since the mm can drop 212 * undirtied hole pages behind our back. 213 * 214 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 215 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 216 * 217 * It has to be called with the spinlock held. 218 */ 219 static void shmem_recalc_inode(struct inode *inode) 220 { 221 struct shmem_inode_info *info = SHMEM_I(inode); 222 long freed; 223 224 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 225 if (freed > 0) { 226 info->alloced -= freed; 227 shmem_unacct_blocks(info->flags, freed); 228 shmem_free_blocks(inode, freed); 229 } 230 } 231 232 /* 233 * shmem_swp_entry - find the swap vector position in the info structure 234 * 235 * @info: info structure for the inode 236 * @index: index of the page to find 237 * @page: optional page to add to the structure. Has to be preset to 238 * all zeros 239 * 240 * If there is no space allocated yet it will return NULL when 241 * page is NULL, else it will use the page for the needed block, 242 * setting it to NULL on return to indicate that it has been used. 243 * 244 * The swap vector is organized the following way: 245 * 246 * There are SHMEM_NR_DIRECT entries directly stored in the 247 * shmem_inode_info structure. So small files do not need an addional 248 * allocation. 249 * 250 * For pages with index > SHMEM_NR_DIRECT there is the pointer 251 * i_indirect which points to a page which holds in the first half 252 * doubly indirect blocks, in the second half triple indirect blocks: 253 * 254 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 255 * following layout (for SHMEM_NR_DIRECT == 16): 256 * 257 * i_indirect -> dir --> 16-19 258 * | +-> 20-23 259 * | 260 * +-->dir2 --> 24-27 261 * | +-> 28-31 262 * | +-> 32-35 263 * | +-> 36-39 264 * | 265 * +-->dir3 --> 40-43 266 * +-> 44-47 267 * +-> 48-51 268 * +-> 52-55 269 */ 270 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 271 { 272 unsigned long offset; 273 struct page **dir; 274 struct page *subdir; 275 276 if (index < SHMEM_NR_DIRECT) { 277 shmem_swp_balance_unmap(); 278 return info->i_direct+index; 279 } 280 if (!info->i_indirect) { 281 if (page) { 282 info->i_indirect = *page; 283 *page = NULL; 284 } 285 return NULL; /* need another page */ 286 } 287 288 index -= SHMEM_NR_DIRECT; 289 offset = index % ENTRIES_PER_PAGE; 290 index /= ENTRIES_PER_PAGE; 291 dir = shmem_dir_map(info->i_indirect); 292 293 if (index >= ENTRIES_PER_PAGE/2) { 294 index -= ENTRIES_PER_PAGE/2; 295 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 296 index %= ENTRIES_PER_PAGE; 297 subdir = *dir; 298 if (!subdir) { 299 if (page) { 300 *dir = *page; 301 *page = NULL; 302 } 303 shmem_dir_unmap(dir); 304 return NULL; /* need another page */ 305 } 306 shmem_dir_unmap(dir); 307 dir = shmem_dir_map(subdir); 308 } 309 310 dir += index; 311 subdir = *dir; 312 if (!subdir) { 313 if (!page || !(subdir = *page)) { 314 shmem_dir_unmap(dir); 315 return NULL; /* need a page */ 316 } 317 *dir = subdir; 318 *page = NULL; 319 } 320 shmem_dir_unmap(dir); 321 return shmem_swp_map(subdir) + offset; 322 } 323 324 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 325 { 326 long incdec = value? 1: -1; 327 328 entry->val = value; 329 info->swapped += incdec; 330 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 331 struct page *page = kmap_atomic_to_page(entry); 332 set_page_private(page, page_private(page) + incdec); 333 } 334 } 335 336 /* 337 * shmem_swp_alloc - get the position of the swap entry for the page. 338 * If it does not exist allocate the entry. 339 * 340 * @info: info structure for the inode 341 * @index: index of the page to find 342 * @sgp: check and recheck i_size? skip allocation? 343 */ 344 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 345 { 346 struct inode *inode = &info->vfs_inode; 347 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 348 struct page *page = NULL; 349 swp_entry_t *entry; 350 351 if (sgp != SGP_WRITE && 352 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 353 return ERR_PTR(-EINVAL); 354 355 while (!(entry = shmem_swp_entry(info, index, &page))) { 356 if (sgp == SGP_READ) 357 return shmem_swp_map(ZERO_PAGE(0)); 358 /* 359 * Test free_blocks against 1 not 0, since we have 1 data 360 * page (and perhaps indirect index pages) yet to allocate: 361 * a waste to allocate index if we cannot allocate data. 362 */ 363 if (sbinfo->max_blocks) { 364 spin_lock(&sbinfo->stat_lock); 365 if (sbinfo->free_blocks <= 1) { 366 spin_unlock(&sbinfo->stat_lock); 367 return ERR_PTR(-ENOSPC); 368 } 369 sbinfo->free_blocks--; 370 inode->i_blocks += BLOCKS_PER_PAGE; 371 spin_unlock(&sbinfo->stat_lock); 372 } 373 374 spin_unlock(&info->lock); 375 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); 376 if (page) 377 set_page_private(page, 0); 378 spin_lock(&info->lock); 379 380 if (!page) { 381 shmem_free_blocks(inode, 1); 382 return ERR_PTR(-ENOMEM); 383 } 384 if (sgp != SGP_WRITE && 385 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 386 entry = ERR_PTR(-EINVAL); 387 break; 388 } 389 if (info->next_index <= index) 390 info->next_index = index + 1; 391 } 392 if (page) { 393 /* another task gave its page, or truncated the file */ 394 shmem_free_blocks(inode, 1); 395 shmem_dir_free(page); 396 } 397 if (info->next_index <= index && !IS_ERR(entry)) 398 info->next_index = index + 1; 399 return entry; 400 } 401 402 /* 403 * shmem_free_swp - free some swap entries in a directory 404 * 405 * @dir: pointer to the directory 406 * @edir: pointer after last entry of the directory 407 * @punch_lock: pointer to spinlock when needed for the holepunch case 408 */ 409 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, 410 spinlock_t *punch_lock) 411 { 412 spinlock_t *punch_unlock = NULL; 413 swp_entry_t *ptr; 414 int freed = 0; 415 416 for (ptr = dir; ptr < edir; ptr++) { 417 if (ptr->val) { 418 if (unlikely(punch_lock)) { 419 punch_unlock = punch_lock; 420 punch_lock = NULL; 421 spin_lock(punch_unlock); 422 if (!ptr->val) 423 continue; 424 } 425 free_swap_and_cache(*ptr); 426 *ptr = (swp_entry_t){0}; 427 freed++; 428 } 429 } 430 if (punch_unlock) 431 spin_unlock(punch_unlock); 432 return freed; 433 } 434 435 static int shmem_map_and_free_swp(struct page *subdir, int offset, 436 int limit, struct page ***dir, spinlock_t *punch_lock) 437 { 438 swp_entry_t *ptr; 439 int freed = 0; 440 441 ptr = shmem_swp_map(subdir); 442 for (; offset < limit; offset += LATENCY_LIMIT) { 443 int size = limit - offset; 444 if (size > LATENCY_LIMIT) 445 size = LATENCY_LIMIT; 446 freed += shmem_free_swp(ptr+offset, ptr+offset+size, 447 punch_lock); 448 if (need_resched()) { 449 shmem_swp_unmap(ptr); 450 if (*dir) { 451 shmem_dir_unmap(*dir); 452 *dir = NULL; 453 } 454 cond_resched(); 455 ptr = shmem_swp_map(subdir); 456 } 457 } 458 shmem_swp_unmap(ptr); 459 return freed; 460 } 461 462 static void shmem_free_pages(struct list_head *next) 463 { 464 struct page *page; 465 int freed = 0; 466 467 do { 468 page = container_of(next, struct page, lru); 469 next = next->next; 470 shmem_dir_free(page); 471 freed++; 472 if (freed >= LATENCY_LIMIT) { 473 cond_resched(); 474 freed = 0; 475 } 476 } while (next); 477 } 478 479 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 480 { 481 struct shmem_inode_info *info = SHMEM_I(inode); 482 unsigned long idx; 483 unsigned long size; 484 unsigned long limit; 485 unsigned long stage; 486 unsigned long diroff; 487 struct page **dir; 488 struct page *topdir; 489 struct page *middir; 490 struct page *subdir; 491 swp_entry_t *ptr; 492 LIST_HEAD(pages_to_free); 493 long nr_pages_to_free = 0; 494 long nr_swaps_freed = 0; 495 int offset; 496 int freed; 497 int punch_hole; 498 spinlock_t *needs_lock; 499 spinlock_t *punch_lock; 500 unsigned long upper_limit; 501 502 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 503 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 504 if (idx >= info->next_index) 505 return; 506 507 spin_lock(&info->lock); 508 info->flags |= SHMEM_TRUNCATE; 509 if (likely(end == (loff_t) -1)) { 510 limit = info->next_index; 511 upper_limit = SHMEM_MAX_INDEX; 512 info->next_index = idx; 513 needs_lock = NULL; 514 punch_hole = 0; 515 } else { 516 if (end + 1 >= inode->i_size) { /* we may free a little more */ 517 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> 518 PAGE_CACHE_SHIFT; 519 upper_limit = SHMEM_MAX_INDEX; 520 } else { 521 limit = (end + 1) >> PAGE_CACHE_SHIFT; 522 upper_limit = limit; 523 } 524 needs_lock = &info->lock; 525 punch_hole = 1; 526 } 527 528 topdir = info->i_indirect; 529 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 530 info->i_indirect = NULL; 531 nr_pages_to_free++; 532 list_add(&topdir->lru, &pages_to_free); 533 } 534 spin_unlock(&info->lock); 535 536 if (info->swapped && idx < SHMEM_NR_DIRECT) { 537 ptr = info->i_direct; 538 size = limit; 539 if (size > SHMEM_NR_DIRECT) 540 size = SHMEM_NR_DIRECT; 541 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); 542 } 543 544 /* 545 * If there are no indirect blocks or we are punching a hole 546 * below indirect blocks, nothing to be done. 547 */ 548 if (!topdir || limit <= SHMEM_NR_DIRECT) 549 goto done2; 550 551 /* 552 * The truncation case has already dropped info->lock, and we're safe 553 * because i_size and next_index have already been lowered, preventing 554 * access beyond. But in the punch_hole case, we still need to take 555 * the lock when updating the swap directory, because there might be 556 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or 557 * shmem_writepage. However, whenever we find we can remove a whole 558 * directory page (not at the misaligned start or end of the range), 559 * we first NULLify its pointer in the level above, and then have no 560 * need to take the lock when updating its contents: needs_lock and 561 * punch_lock (either pointing to info->lock or NULL) manage this. 562 */ 563 564 upper_limit -= SHMEM_NR_DIRECT; 565 limit -= SHMEM_NR_DIRECT; 566 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 567 offset = idx % ENTRIES_PER_PAGE; 568 idx -= offset; 569 570 dir = shmem_dir_map(topdir); 571 stage = ENTRIES_PER_PAGEPAGE/2; 572 if (idx < ENTRIES_PER_PAGEPAGE/2) { 573 middir = topdir; 574 diroff = idx/ENTRIES_PER_PAGE; 575 } else { 576 dir += ENTRIES_PER_PAGE/2; 577 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 578 while (stage <= idx) 579 stage += ENTRIES_PER_PAGEPAGE; 580 middir = *dir; 581 if (*dir) { 582 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 583 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 584 if (!diroff && !offset && upper_limit >= stage) { 585 if (needs_lock) { 586 spin_lock(needs_lock); 587 *dir = NULL; 588 spin_unlock(needs_lock); 589 needs_lock = NULL; 590 } else 591 *dir = NULL; 592 nr_pages_to_free++; 593 list_add(&middir->lru, &pages_to_free); 594 } 595 shmem_dir_unmap(dir); 596 dir = shmem_dir_map(middir); 597 } else { 598 diroff = 0; 599 offset = 0; 600 idx = stage; 601 } 602 } 603 604 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 605 if (unlikely(idx == stage)) { 606 shmem_dir_unmap(dir); 607 dir = shmem_dir_map(topdir) + 608 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 609 while (!*dir) { 610 dir++; 611 idx += ENTRIES_PER_PAGEPAGE; 612 if (idx >= limit) 613 goto done1; 614 } 615 stage = idx + ENTRIES_PER_PAGEPAGE; 616 middir = *dir; 617 if (punch_hole) 618 needs_lock = &info->lock; 619 if (upper_limit >= stage) { 620 if (needs_lock) { 621 spin_lock(needs_lock); 622 *dir = NULL; 623 spin_unlock(needs_lock); 624 needs_lock = NULL; 625 } else 626 *dir = NULL; 627 nr_pages_to_free++; 628 list_add(&middir->lru, &pages_to_free); 629 } 630 shmem_dir_unmap(dir); 631 cond_resched(); 632 dir = shmem_dir_map(middir); 633 diroff = 0; 634 } 635 punch_lock = needs_lock; 636 subdir = dir[diroff]; 637 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { 638 if (needs_lock) { 639 spin_lock(needs_lock); 640 dir[diroff] = NULL; 641 spin_unlock(needs_lock); 642 punch_lock = NULL; 643 } else 644 dir[diroff] = NULL; 645 nr_pages_to_free++; 646 list_add(&subdir->lru, &pages_to_free); 647 } 648 if (subdir && page_private(subdir) /* has swap entries */) { 649 size = limit - idx; 650 if (size > ENTRIES_PER_PAGE) 651 size = ENTRIES_PER_PAGE; 652 freed = shmem_map_and_free_swp(subdir, 653 offset, size, &dir, punch_lock); 654 if (!dir) 655 dir = shmem_dir_map(middir); 656 nr_swaps_freed += freed; 657 if (offset || punch_lock) { 658 spin_lock(&info->lock); 659 set_page_private(subdir, 660 page_private(subdir) - freed); 661 spin_unlock(&info->lock); 662 } else 663 BUG_ON(page_private(subdir) != freed); 664 } 665 offset = 0; 666 } 667 done1: 668 shmem_dir_unmap(dir); 669 done2: 670 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 671 /* 672 * Call truncate_inode_pages again: racing shmem_unuse_inode 673 * may have swizzled a page in from swap since vmtruncate or 674 * generic_delete_inode did it, before we lowered next_index. 675 * Also, though shmem_getpage checks i_size before adding to 676 * cache, no recheck after: so fix the narrow window there too. 677 * 678 * Recalling truncate_inode_pages_range and unmap_mapping_range 679 * every time for punch_hole (which never got a chance to clear 680 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 681 * yet hardly ever necessary: try to optimize them out later. 682 */ 683 truncate_inode_pages_range(inode->i_mapping, start, end); 684 if (punch_hole) 685 unmap_mapping_range(inode->i_mapping, start, 686 end - start, 1); 687 } 688 689 spin_lock(&info->lock); 690 info->flags &= ~SHMEM_TRUNCATE; 691 info->swapped -= nr_swaps_freed; 692 if (nr_pages_to_free) 693 shmem_free_blocks(inode, nr_pages_to_free); 694 shmem_recalc_inode(inode); 695 spin_unlock(&info->lock); 696 697 /* 698 * Empty swap vector directory pages to be freed? 699 */ 700 if (!list_empty(&pages_to_free)) { 701 pages_to_free.prev->next = NULL; 702 shmem_free_pages(pages_to_free.next); 703 } 704 } 705 706 static void shmem_truncate(struct inode *inode) 707 { 708 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 709 } 710 711 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 712 { 713 struct inode *inode = dentry->d_inode; 714 struct page *page = NULL; 715 int error; 716 717 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 718 if (attr->ia_size < inode->i_size) { 719 /* 720 * If truncating down to a partial page, then 721 * if that page is already allocated, hold it 722 * in memory until the truncation is over, so 723 * truncate_partial_page cannnot miss it were 724 * it assigned to swap. 725 */ 726 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 727 (void) shmem_getpage(inode, 728 attr->ia_size>>PAGE_CACHE_SHIFT, 729 &page, SGP_READ, NULL); 730 } 731 /* 732 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 733 * detect if any pages might have been added to cache 734 * after truncate_inode_pages. But we needn't bother 735 * if it's being fully truncated to zero-length: the 736 * nrpages check is efficient enough in that case. 737 */ 738 if (attr->ia_size) { 739 struct shmem_inode_info *info = SHMEM_I(inode); 740 spin_lock(&info->lock); 741 info->flags &= ~SHMEM_PAGEIN; 742 spin_unlock(&info->lock); 743 } 744 } 745 } 746 747 error = inode_change_ok(inode, attr); 748 if (!error) 749 error = inode_setattr(inode, attr); 750 #ifdef CONFIG_TMPFS_POSIX_ACL 751 if (!error && (attr->ia_valid & ATTR_MODE)) 752 error = generic_acl_chmod(inode, &shmem_acl_ops); 753 #endif 754 if (page) 755 page_cache_release(page); 756 return error; 757 } 758 759 static void shmem_delete_inode(struct inode *inode) 760 { 761 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 762 struct shmem_inode_info *info = SHMEM_I(inode); 763 764 if (inode->i_op->truncate == shmem_truncate) { 765 truncate_inode_pages(inode->i_mapping, 0); 766 shmem_unacct_size(info->flags, inode->i_size); 767 inode->i_size = 0; 768 shmem_truncate(inode); 769 if (!list_empty(&info->swaplist)) { 770 spin_lock(&shmem_swaplist_lock); 771 list_del_init(&info->swaplist); 772 spin_unlock(&shmem_swaplist_lock); 773 } 774 } 775 BUG_ON(inode->i_blocks); 776 if (sbinfo->max_inodes) { 777 spin_lock(&sbinfo->stat_lock); 778 sbinfo->free_inodes++; 779 spin_unlock(&sbinfo->stat_lock); 780 } 781 clear_inode(inode); 782 } 783 784 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 785 { 786 swp_entry_t *ptr; 787 788 for (ptr = dir; ptr < edir; ptr++) { 789 if (ptr->val == entry.val) 790 return ptr - dir; 791 } 792 return -1; 793 } 794 795 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 796 { 797 struct inode *inode; 798 unsigned long idx; 799 unsigned long size; 800 unsigned long limit; 801 unsigned long stage; 802 struct page **dir; 803 struct page *subdir; 804 swp_entry_t *ptr; 805 int offset; 806 807 idx = 0; 808 ptr = info->i_direct; 809 spin_lock(&info->lock); 810 limit = info->next_index; 811 size = limit; 812 if (size > SHMEM_NR_DIRECT) 813 size = SHMEM_NR_DIRECT; 814 offset = shmem_find_swp(entry, ptr, ptr+size); 815 if (offset >= 0) { 816 shmem_swp_balance_unmap(); 817 goto found; 818 } 819 if (!info->i_indirect) 820 goto lost2; 821 822 dir = shmem_dir_map(info->i_indirect); 823 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 824 825 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 826 if (unlikely(idx == stage)) { 827 shmem_dir_unmap(dir-1); 828 dir = shmem_dir_map(info->i_indirect) + 829 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 830 while (!*dir) { 831 dir++; 832 idx += ENTRIES_PER_PAGEPAGE; 833 if (idx >= limit) 834 goto lost1; 835 } 836 stage = idx + ENTRIES_PER_PAGEPAGE; 837 subdir = *dir; 838 shmem_dir_unmap(dir); 839 dir = shmem_dir_map(subdir); 840 } 841 subdir = *dir; 842 if (subdir && page_private(subdir)) { 843 ptr = shmem_swp_map(subdir); 844 size = limit - idx; 845 if (size > ENTRIES_PER_PAGE) 846 size = ENTRIES_PER_PAGE; 847 offset = shmem_find_swp(entry, ptr, ptr+size); 848 if (offset >= 0) { 849 shmem_dir_unmap(dir); 850 goto found; 851 } 852 shmem_swp_unmap(ptr); 853 } 854 } 855 lost1: 856 shmem_dir_unmap(dir-1); 857 lost2: 858 spin_unlock(&info->lock); 859 return 0; 860 found: 861 idx += offset; 862 inode = &info->vfs_inode; 863 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 864 info->flags |= SHMEM_PAGEIN; 865 shmem_swp_set(info, ptr + offset, 0); 866 } 867 shmem_swp_unmap(ptr); 868 spin_unlock(&info->lock); 869 /* 870 * Decrement swap count even when the entry is left behind: 871 * try_to_unuse will skip over mms, then reincrement count. 872 */ 873 swap_free(entry); 874 return 1; 875 } 876 877 /* 878 * shmem_unuse() search for an eventually swapped out shmem page. 879 */ 880 int shmem_unuse(swp_entry_t entry, struct page *page) 881 { 882 struct list_head *p, *next; 883 struct shmem_inode_info *info; 884 int found = 0; 885 886 spin_lock(&shmem_swaplist_lock); 887 list_for_each_safe(p, next, &shmem_swaplist) { 888 info = list_entry(p, struct shmem_inode_info, swaplist); 889 if (!info->swapped) 890 list_del_init(&info->swaplist); 891 else if (shmem_unuse_inode(info, entry, page)) { 892 /* move head to start search for next from here */ 893 list_move_tail(&shmem_swaplist, &info->swaplist); 894 found = 1; 895 break; 896 } 897 } 898 spin_unlock(&shmem_swaplist_lock); 899 return found; 900 } 901 902 /* 903 * Move the page from the page cache to the swap cache. 904 */ 905 static int shmem_writepage(struct page *page, struct writeback_control *wbc) 906 { 907 struct shmem_inode_info *info; 908 swp_entry_t *entry, swap; 909 struct address_space *mapping; 910 unsigned long index; 911 struct inode *inode; 912 913 BUG_ON(!PageLocked(page)); 914 BUG_ON(page_mapped(page)); 915 916 mapping = page->mapping; 917 index = page->index; 918 inode = mapping->host; 919 info = SHMEM_I(inode); 920 if (info->flags & VM_LOCKED) 921 goto redirty; 922 swap = get_swap_page(); 923 if (!swap.val) 924 goto redirty; 925 926 spin_lock(&info->lock); 927 shmem_recalc_inode(inode); 928 if (index >= info->next_index) { 929 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 930 goto unlock; 931 } 932 entry = shmem_swp_entry(info, index, NULL); 933 BUG_ON(!entry); 934 BUG_ON(entry->val); 935 936 if (move_to_swap_cache(page, swap) == 0) { 937 shmem_swp_set(info, entry, swap.val); 938 shmem_swp_unmap(entry); 939 spin_unlock(&info->lock); 940 if (list_empty(&info->swaplist)) { 941 spin_lock(&shmem_swaplist_lock); 942 /* move instead of add in case we're racing */ 943 list_move_tail(&info->swaplist, &shmem_swaplist); 944 spin_unlock(&shmem_swaplist_lock); 945 } 946 unlock_page(page); 947 return 0; 948 } 949 950 shmem_swp_unmap(entry); 951 unlock: 952 spin_unlock(&info->lock); 953 swap_free(swap); 954 redirty: 955 set_page_dirty(page); 956 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ 957 } 958 959 #ifdef CONFIG_NUMA 960 static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 961 { 962 char *nodelist = strchr(value, ':'); 963 int err = 1; 964 965 if (nodelist) { 966 /* NUL-terminate policy string */ 967 *nodelist++ = '\0'; 968 if (nodelist_parse(nodelist, *policy_nodes)) 969 goto out; 970 } 971 if (!strcmp(value, "default")) { 972 *policy = MPOL_DEFAULT; 973 /* Don't allow a nodelist */ 974 if (!nodelist) 975 err = 0; 976 } else if (!strcmp(value, "prefer")) { 977 *policy = MPOL_PREFERRED; 978 /* Insist on a nodelist of one node only */ 979 if (nodelist) { 980 char *rest = nodelist; 981 while (isdigit(*rest)) 982 rest++; 983 if (!*rest) 984 err = 0; 985 } 986 } else if (!strcmp(value, "bind")) { 987 *policy = MPOL_BIND; 988 /* Insist on a nodelist */ 989 if (nodelist) 990 err = 0; 991 } else if (!strcmp(value, "interleave")) { 992 *policy = MPOL_INTERLEAVE; 993 /* Default to nodes online if no nodelist */ 994 if (!nodelist) 995 *policy_nodes = node_online_map; 996 err = 0; 997 } 998 out: 999 /* Restore string for error message */ 1000 if (nodelist) 1001 *--nodelist = ':'; 1002 return err; 1003 } 1004 1005 static struct page *shmem_swapin_async(struct shared_policy *p, 1006 swp_entry_t entry, unsigned long idx) 1007 { 1008 struct page *page; 1009 struct vm_area_struct pvma; 1010 1011 /* Create a pseudo vma that just contains the policy */ 1012 memset(&pvma, 0, sizeof(struct vm_area_struct)); 1013 pvma.vm_end = PAGE_SIZE; 1014 pvma.vm_pgoff = idx; 1015 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 1016 page = read_swap_cache_async(entry, &pvma, 0); 1017 mpol_free(pvma.vm_policy); 1018 return page; 1019 } 1020 1021 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 1022 unsigned long idx) 1023 { 1024 struct shared_policy *p = &info->policy; 1025 int i, num; 1026 struct page *page; 1027 unsigned long offset; 1028 1029 num = valid_swaphandles(entry, &offset); 1030 for (i = 0; i < num; offset++, i++) { 1031 page = shmem_swapin_async(p, 1032 swp_entry(swp_type(entry), offset), idx); 1033 if (!page) 1034 break; 1035 page_cache_release(page); 1036 } 1037 lru_add_drain(); /* Push any new pages onto the LRU now */ 1038 return shmem_swapin_async(p, entry, idx); 1039 } 1040 1041 static struct page * 1042 shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, 1043 unsigned long idx) 1044 { 1045 struct vm_area_struct pvma; 1046 struct page *page; 1047 1048 memset(&pvma, 0, sizeof(struct vm_area_struct)); 1049 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1050 pvma.vm_pgoff = idx; 1051 pvma.vm_end = PAGE_SIZE; 1052 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 1053 mpol_free(pvma.vm_policy); 1054 return page; 1055 } 1056 #else 1057 static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 1058 { 1059 return 1; 1060 } 1061 1062 static inline struct page * 1063 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 1064 { 1065 swapin_readahead(entry, 0, NULL); 1066 return read_swap_cache_async(entry, NULL, 0); 1067 } 1068 1069 static inline struct page * 1070 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) 1071 { 1072 return alloc_page(gfp | __GFP_ZERO); 1073 } 1074 #endif 1075 1076 /* 1077 * shmem_getpage - either get the page from swap or allocate a new one 1078 * 1079 * If we allocate a new one we do not mark it dirty. That's up to the 1080 * vm. If we swap it in we mark it dirty since we also free the swap 1081 * entry since a page cannot live in both the swap and page cache 1082 */ 1083 static int shmem_getpage(struct inode *inode, unsigned long idx, 1084 struct page **pagep, enum sgp_type sgp, int *type) 1085 { 1086 struct address_space *mapping = inode->i_mapping; 1087 struct shmem_inode_info *info = SHMEM_I(inode); 1088 struct shmem_sb_info *sbinfo; 1089 struct page *filepage = *pagep; 1090 struct page *swappage; 1091 swp_entry_t *entry; 1092 swp_entry_t swap; 1093 int error; 1094 1095 if (idx >= SHMEM_MAX_INDEX) 1096 return -EFBIG; 1097 /* 1098 * Normally, filepage is NULL on entry, and either found 1099 * uptodate immediately, or allocated and zeroed, or read 1100 * in under swappage, which is then assigned to filepage. 1101 * But shmem_prepare_write passes in a locked filepage, 1102 * which may be found not uptodate by other callers too, 1103 * and may need to be copied from the swappage read in. 1104 */ 1105 repeat: 1106 if (!filepage) 1107 filepage = find_lock_page(mapping, idx); 1108 if (filepage && PageUptodate(filepage)) 1109 goto done; 1110 error = 0; 1111 if (sgp == SGP_QUICK) 1112 goto failed; 1113 1114 spin_lock(&info->lock); 1115 shmem_recalc_inode(inode); 1116 entry = shmem_swp_alloc(info, idx, sgp); 1117 if (IS_ERR(entry)) { 1118 spin_unlock(&info->lock); 1119 error = PTR_ERR(entry); 1120 goto failed; 1121 } 1122 swap = *entry; 1123 1124 if (swap.val) { 1125 /* Look it up and read it in.. */ 1126 swappage = lookup_swap_cache(swap); 1127 if (!swappage) { 1128 shmem_swp_unmap(entry); 1129 /* here we actually do the io */ 1130 if (type && *type == VM_FAULT_MINOR) { 1131 __count_vm_event(PGMAJFAULT); 1132 *type = VM_FAULT_MAJOR; 1133 } 1134 spin_unlock(&info->lock); 1135 swappage = shmem_swapin(info, swap, idx); 1136 if (!swappage) { 1137 spin_lock(&info->lock); 1138 entry = shmem_swp_alloc(info, idx, sgp); 1139 if (IS_ERR(entry)) 1140 error = PTR_ERR(entry); 1141 else { 1142 if (entry->val == swap.val) 1143 error = -ENOMEM; 1144 shmem_swp_unmap(entry); 1145 } 1146 spin_unlock(&info->lock); 1147 if (error) 1148 goto failed; 1149 goto repeat; 1150 } 1151 wait_on_page_locked(swappage); 1152 page_cache_release(swappage); 1153 goto repeat; 1154 } 1155 1156 /* We have to do this with page locked to prevent races */ 1157 if (TestSetPageLocked(swappage)) { 1158 shmem_swp_unmap(entry); 1159 spin_unlock(&info->lock); 1160 wait_on_page_locked(swappage); 1161 page_cache_release(swappage); 1162 goto repeat; 1163 } 1164 if (PageWriteback(swappage)) { 1165 shmem_swp_unmap(entry); 1166 spin_unlock(&info->lock); 1167 wait_on_page_writeback(swappage); 1168 unlock_page(swappage); 1169 page_cache_release(swappage); 1170 goto repeat; 1171 } 1172 if (!PageUptodate(swappage)) { 1173 shmem_swp_unmap(entry); 1174 spin_unlock(&info->lock); 1175 unlock_page(swappage); 1176 page_cache_release(swappage); 1177 error = -EIO; 1178 goto failed; 1179 } 1180 1181 if (filepage) { 1182 shmem_swp_set(info, entry, 0); 1183 shmem_swp_unmap(entry); 1184 delete_from_swap_cache(swappage); 1185 spin_unlock(&info->lock); 1186 copy_highpage(filepage, swappage); 1187 unlock_page(swappage); 1188 page_cache_release(swappage); 1189 flush_dcache_page(filepage); 1190 SetPageUptodate(filepage); 1191 set_page_dirty(filepage); 1192 swap_free(swap); 1193 } else if (!(error = move_from_swap_cache( 1194 swappage, idx, mapping))) { 1195 info->flags |= SHMEM_PAGEIN; 1196 shmem_swp_set(info, entry, 0); 1197 shmem_swp_unmap(entry); 1198 spin_unlock(&info->lock); 1199 filepage = swappage; 1200 swap_free(swap); 1201 } else { 1202 shmem_swp_unmap(entry); 1203 spin_unlock(&info->lock); 1204 unlock_page(swappage); 1205 page_cache_release(swappage); 1206 if (error == -ENOMEM) { 1207 /* let kswapd refresh zone for GFP_ATOMICs */ 1208 congestion_wait(WRITE, HZ/50); 1209 } 1210 goto repeat; 1211 } 1212 } else if (sgp == SGP_READ && !filepage) { 1213 shmem_swp_unmap(entry); 1214 filepage = find_get_page(mapping, idx); 1215 if (filepage && 1216 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1217 spin_unlock(&info->lock); 1218 wait_on_page_locked(filepage); 1219 page_cache_release(filepage); 1220 filepage = NULL; 1221 goto repeat; 1222 } 1223 spin_unlock(&info->lock); 1224 } else { 1225 shmem_swp_unmap(entry); 1226 sbinfo = SHMEM_SB(inode->i_sb); 1227 if (sbinfo->max_blocks) { 1228 spin_lock(&sbinfo->stat_lock); 1229 if (sbinfo->free_blocks == 0 || 1230 shmem_acct_block(info->flags)) { 1231 spin_unlock(&sbinfo->stat_lock); 1232 spin_unlock(&info->lock); 1233 error = -ENOSPC; 1234 goto failed; 1235 } 1236 sbinfo->free_blocks--; 1237 inode->i_blocks += BLOCKS_PER_PAGE; 1238 spin_unlock(&sbinfo->stat_lock); 1239 } else if (shmem_acct_block(info->flags)) { 1240 spin_unlock(&info->lock); 1241 error = -ENOSPC; 1242 goto failed; 1243 } 1244 1245 if (!filepage) { 1246 spin_unlock(&info->lock); 1247 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1248 info, 1249 idx); 1250 if (!filepage) { 1251 shmem_unacct_blocks(info->flags, 1); 1252 shmem_free_blocks(inode, 1); 1253 error = -ENOMEM; 1254 goto failed; 1255 } 1256 1257 spin_lock(&info->lock); 1258 entry = shmem_swp_alloc(info, idx, sgp); 1259 if (IS_ERR(entry)) 1260 error = PTR_ERR(entry); 1261 else { 1262 swap = *entry; 1263 shmem_swp_unmap(entry); 1264 } 1265 if (error || swap.val || 0 != add_to_page_cache_lru( 1266 filepage, mapping, idx, GFP_ATOMIC)) { 1267 spin_unlock(&info->lock); 1268 page_cache_release(filepage); 1269 shmem_unacct_blocks(info->flags, 1); 1270 shmem_free_blocks(inode, 1); 1271 filepage = NULL; 1272 if (error) 1273 goto failed; 1274 goto repeat; 1275 } 1276 info->flags |= SHMEM_PAGEIN; 1277 } 1278 1279 info->alloced++; 1280 spin_unlock(&info->lock); 1281 flush_dcache_page(filepage); 1282 SetPageUptodate(filepage); 1283 } 1284 done: 1285 if (*pagep != filepage) { 1286 unlock_page(filepage); 1287 *pagep = filepage; 1288 } 1289 return 0; 1290 1291 failed: 1292 if (*pagep != filepage) { 1293 unlock_page(filepage); 1294 page_cache_release(filepage); 1295 } 1296 return error; 1297 } 1298 1299 static struct page *shmem_nopage(struct vm_area_struct *vma, 1300 unsigned long address, int *type) 1301 { 1302 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1303 struct page *page = NULL; 1304 unsigned long idx; 1305 int error; 1306 1307 idx = (address - vma->vm_start) >> PAGE_SHIFT; 1308 idx += vma->vm_pgoff; 1309 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; 1310 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1311 return NOPAGE_SIGBUS; 1312 1313 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); 1314 if (error) 1315 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; 1316 1317 mark_page_accessed(page); 1318 return page; 1319 } 1320 1321 static int shmem_populate(struct vm_area_struct *vma, 1322 unsigned long addr, unsigned long len, 1323 pgprot_t prot, unsigned long pgoff, int nonblock) 1324 { 1325 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1326 struct mm_struct *mm = vma->vm_mm; 1327 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; 1328 unsigned long size; 1329 1330 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; 1331 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) 1332 return -EINVAL; 1333 1334 while ((long) len > 0) { 1335 struct page *page = NULL; 1336 int err; 1337 /* 1338 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE 1339 */ 1340 err = shmem_getpage(inode, pgoff, &page, sgp, NULL); 1341 if (err) 1342 return err; 1343 /* Page may still be null, but only if nonblock was set. */ 1344 if (page) { 1345 mark_page_accessed(page); 1346 err = install_page(mm, vma, addr, page, prot); 1347 if (err) { 1348 page_cache_release(page); 1349 return err; 1350 } 1351 } else if (vma->vm_flags & VM_NONLINEAR) { 1352 /* No page was found just because we can't read it in 1353 * now (being here implies nonblock != 0), but the page 1354 * may exist, so set the PTE to fault it in later. */ 1355 err = install_file_pte(mm, vma, addr, pgoff, prot); 1356 if (err) 1357 return err; 1358 } 1359 1360 len -= PAGE_SIZE; 1361 addr += PAGE_SIZE; 1362 pgoff++; 1363 } 1364 return 0; 1365 } 1366 1367 #ifdef CONFIG_NUMA 1368 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1369 { 1370 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1371 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1372 } 1373 1374 struct mempolicy * 1375 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) 1376 { 1377 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1378 unsigned long idx; 1379 1380 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1381 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1382 } 1383 #endif 1384 1385 int shmem_lock(struct file *file, int lock, struct user_struct *user) 1386 { 1387 struct inode *inode = file->f_path.dentry->d_inode; 1388 struct shmem_inode_info *info = SHMEM_I(inode); 1389 int retval = -ENOMEM; 1390 1391 spin_lock(&info->lock); 1392 if (lock && !(info->flags & VM_LOCKED)) { 1393 if (!user_shm_lock(inode->i_size, user)) 1394 goto out_nomem; 1395 info->flags |= VM_LOCKED; 1396 } 1397 if (!lock && (info->flags & VM_LOCKED) && user) { 1398 user_shm_unlock(inode->i_size, user); 1399 info->flags &= ~VM_LOCKED; 1400 } 1401 retval = 0; 1402 out_nomem: 1403 spin_unlock(&info->lock); 1404 return retval; 1405 } 1406 1407 static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1408 { 1409 file_accessed(file); 1410 vma->vm_ops = &shmem_vm_ops; 1411 return 0; 1412 } 1413 1414 static struct inode * 1415 shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1416 { 1417 struct inode *inode; 1418 struct shmem_inode_info *info; 1419 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1420 1421 if (sbinfo->max_inodes) { 1422 spin_lock(&sbinfo->stat_lock); 1423 if (!sbinfo->free_inodes) { 1424 spin_unlock(&sbinfo->stat_lock); 1425 return NULL; 1426 } 1427 sbinfo->free_inodes--; 1428 spin_unlock(&sbinfo->stat_lock); 1429 } 1430 1431 inode = new_inode(sb); 1432 if (inode) { 1433 inode->i_mode = mode; 1434 inode->i_uid = current->fsuid; 1435 inode->i_gid = current->fsgid; 1436 inode->i_blocks = 0; 1437 inode->i_mapping->a_ops = &shmem_aops; 1438 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1439 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1440 inode->i_generation = get_seconds(); 1441 info = SHMEM_I(inode); 1442 memset(info, 0, (char *)inode - (char *)info); 1443 spin_lock_init(&info->lock); 1444 INIT_LIST_HEAD(&info->swaplist); 1445 1446 switch (mode & S_IFMT) { 1447 default: 1448 inode->i_op = &shmem_special_inode_operations; 1449 init_special_inode(inode, mode, dev); 1450 break; 1451 case S_IFREG: 1452 inode->i_op = &shmem_inode_operations; 1453 inode->i_fop = &shmem_file_operations; 1454 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1455 &sbinfo->policy_nodes); 1456 break; 1457 case S_IFDIR: 1458 inc_nlink(inode); 1459 /* Some things misbehave if size == 0 on a directory */ 1460 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1461 inode->i_op = &shmem_dir_inode_operations; 1462 inode->i_fop = &simple_dir_operations; 1463 break; 1464 case S_IFLNK: 1465 /* 1466 * Must not load anything in the rbtree, 1467 * mpol_free_shared_policy will not be called. 1468 */ 1469 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1470 NULL); 1471 break; 1472 } 1473 } else if (sbinfo->max_inodes) { 1474 spin_lock(&sbinfo->stat_lock); 1475 sbinfo->free_inodes++; 1476 spin_unlock(&sbinfo->stat_lock); 1477 } 1478 return inode; 1479 } 1480 1481 #ifdef CONFIG_TMPFS 1482 static const struct inode_operations shmem_symlink_inode_operations; 1483 static const struct inode_operations shmem_symlink_inline_operations; 1484 1485 /* 1486 * Normally tmpfs makes no use of shmem_prepare_write, but it 1487 * lets a tmpfs file be used read-write below the loop driver. 1488 */ 1489 static int 1490 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) 1491 { 1492 struct inode *inode = page->mapping->host; 1493 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); 1494 } 1495 1496 static ssize_t 1497 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1498 { 1499 struct inode *inode = file->f_path.dentry->d_inode; 1500 loff_t pos; 1501 unsigned long written; 1502 ssize_t err; 1503 1504 if ((ssize_t) count < 0) 1505 return -EINVAL; 1506 1507 if (!access_ok(VERIFY_READ, buf, count)) 1508 return -EFAULT; 1509 1510 mutex_lock(&inode->i_mutex); 1511 1512 pos = *ppos; 1513 written = 0; 1514 1515 err = generic_write_checks(file, &pos, &count, 0); 1516 if (err || !count) 1517 goto out; 1518 1519 err = remove_suid(file->f_path.dentry); 1520 if (err) 1521 goto out; 1522 1523 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1524 1525 do { 1526 struct page *page = NULL; 1527 unsigned long bytes, index, offset; 1528 char *kaddr; 1529 int left; 1530 1531 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1532 index = pos >> PAGE_CACHE_SHIFT; 1533 bytes = PAGE_CACHE_SIZE - offset; 1534 if (bytes > count) 1535 bytes = count; 1536 1537 /* 1538 * We don't hold page lock across copy from user - 1539 * what would it guard against? - so no deadlock here. 1540 * But it still may be a good idea to prefault below. 1541 */ 1542 1543 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1544 if (err) 1545 break; 1546 1547 left = bytes; 1548 if (PageHighMem(page)) { 1549 volatile unsigned char dummy; 1550 __get_user(dummy, buf); 1551 __get_user(dummy, buf + bytes - 1); 1552 1553 kaddr = kmap_atomic(page, KM_USER0); 1554 left = __copy_from_user_inatomic(kaddr + offset, 1555 buf, bytes); 1556 kunmap_atomic(kaddr, KM_USER0); 1557 } 1558 if (left) { 1559 kaddr = kmap(page); 1560 left = __copy_from_user(kaddr + offset, buf, bytes); 1561 kunmap(page); 1562 } 1563 1564 written += bytes; 1565 count -= bytes; 1566 pos += bytes; 1567 buf += bytes; 1568 if (pos > inode->i_size) 1569 i_size_write(inode, pos); 1570 1571 flush_dcache_page(page); 1572 set_page_dirty(page); 1573 mark_page_accessed(page); 1574 page_cache_release(page); 1575 1576 if (left) { 1577 pos -= left; 1578 written -= left; 1579 err = -EFAULT; 1580 break; 1581 } 1582 1583 /* 1584 * Our dirty pages are not counted in nr_dirty, 1585 * and we do not attempt to balance dirty pages. 1586 */ 1587 1588 cond_resched(); 1589 } while (count); 1590 1591 *ppos = pos; 1592 if (written) 1593 err = written; 1594 out: 1595 mutex_unlock(&inode->i_mutex); 1596 return err; 1597 } 1598 1599 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1600 { 1601 struct inode *inode = filp->f_path.dentry->d_inode; 1602 struct address_space *mapping = inode->i_mapping; 1603 unsigned long index, offset; 1604 1605 index = *ppos >> PAGE_CACHE_SHIFT; 1606 offset = *ppos & ~PAGE_CACHE_MASK; 1607 1608 for (;;) { 1609 struct page *page = NULL; 1610 unsigned long end_index, nr, ret; 1611 loff_t i_size = i_size_read(inode); 1612 1613 end_index = i_size >> PAGE_CACHE_SHIFT; 1614 if (index > end_index) 1615 break; 1616 if (index == end_index) { 1617 nr = i_size & ~PAGE_CACHE_MASK; 1618 if (nr <= offset) 1619 break; 1620 } 1621 1622 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1623 if (desc->error) { 1624 if (desc->error == -EINVAL) 1625 desc->error = 0; 1626 break; 1627 } 1628 1629 /* 1630 * We must evaluate after, since reads (unlike writes) 1631 * are called without i_mutex protection against truncate 1632 */ 1633 nr = PAGE_CACHE_SIZE; 1634 i_size = i_size_read(inode); 1635 end_index = i_size >> PAGE_CACHE_SHIFT; 1636 if (index == end_index) { 1637 nr = i_size & ~PAGE_CACHE_MASK; 1638 if (nr <= offset) { 1639 if (page) 1640 page_cache_release(page); 1641 break; 1642 } 1643 } 1644 nr -= offset; 1645 1646 if (page) { 1647 /* 1648 * If users can be writing to this page using arbitrary 1649 * virtual addresses, take care about potential aliasing 1650 * before reading the page on the kernel side. 1651 */ 1652 if (mapping_writably_mapped(mapping)) 1653 flush_dcache_page(page); 1654 /* 1655 * Mark the page accessed if we read the beginning. 1656 */ 1657 if (!offset) 1658 mark_page_accessed(page); 1659 } else { 1660 page = ZERO_PAGE(0); 1661 page_cache_get(page); 1662 } 1663 1664 /* 1665 * Ok, we have the page, and it's up-to-date, so 1666 * now we can copy it to user space... 1667 * 1668 * The actor routine returns how many bytes were actually used.. 1669 * NOTE! This may not be the same as how much of a user buffer 1670 * we filled up (we may be padding etc), so we can only update 1671 * "pos" here (the actor routine has to update the user buffer 1672 * pointers and the remaining count). 1673 */ 1674 ret = actor(desc, page, offset, nr); 1675 offset += ret; 1676 index += offset >> PAGE_CACHE_SHIFT; 1677 offset &= ~PAGE_CACHE_MASK; 1678 1679 page_cache_release(page); 1680 if (ret != nr || !desc->count) 1681 break; 1682 1683 cond_resched(); 1684 } 1685 1686 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1687 file_accessed(filp); 1688 } 1689 1690 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1691 { 1692 read_descriptor_t desc; 1693 1694 if ((ssize_t) count < 0) 1695 return -EINVAL; 1696 if (!access_ok(VERIFY_WRITE, buf, count)) 1697 return -EFAULT; 1698 if (!count) 1699 return 0; 1700 1701 desc.written = 0; 1702 desc.count = count; 1703 desc.arg.buf = buf; 1704 desc.error = 0; 1705 1706 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1707 if (desc.written) 1708 return desc.written; 1709 return desc.error; 1710 } 1711 1712 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, 1713 size_t count, read_actor_t actor, void *target) 1714 { 1715 read_descriptor_t desc; 1716 1717 if (!count) 1718 return 0; 1719 1720 desc.written = 0; 1721 desc.count = count; 1722 desc.arg.data = target; 1723 desc.error = 0; 1724 1725 do_shmem_file_read(in_file, ppos, &desc, actor); 1726 if (desc.written) 1727 return desc.written; 1728 return desc.error; 1729 } 1730 1731 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1732 { 1733 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1734 1735 buf->f_type = TMPFS_MAGIC; 1736 buf->f_bsize = PAGE_CACHE_SIZE; 1737 buf->f_namelen = NAME_MAX; 1738 spin_lock(&sbinfo->stat_lock); 1739 if (sbinfo->max_blocks) { 1740 buf->f_blocks = sbinfo->max_blocks; 1741 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1742 } 1743 if (sbinfo->max_inodes) { 1744 buf->f_files = sbinfo->max_inodes; 1745 buf->f_ffree = sbinfo->free_inodes; 1746 } 1747 /* else leave those fields 0 like simple_statfs */ 1748 spin_unlock(&sbinfo->stat_lock); 1749 return 0; 1750 } 1751 1752 /* 1753 * File creation. Allocate an inode, and we're done.. 1754 */ 1755 static int 1756 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1757 { 1758 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1759 int error = -ENOSPC; 1760 1761 if (inode) { 1762 error = security_inode_init_security(inode, dir, NULL, NULL, 1763 NULL); 1764 if (error) { 1765 if (error != -EOPNOTSUPP) { 1766 iput(inode); 1767 return error; 1768 } 1769 } 1770 error = shmem_acl_init(inode, dir); 1771 if (error) { 1772 iput(inode); 1773 return error; 1774 } 1775 if (dir->i_mode & S_ISGID) { 1776 inode->i_gid = dir->i_gid; 1777 if (S_ISDIR(mode)) 1778 inode->i_mode |= S_ISGID; 1779 } 1780 dir->i_size += BOGO_DIRENT_SIZE; 1781 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1782 d_instantiate(dentry, inode); 1783 dget(dentry); /* Extra count - pin the dentry in core */ 1784 } 1785 return error; 1786 } 1787 1788 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1789 { 1790 int error; 1791 1792 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1793 return error; 1794 inc_nlink(dir); 1795 return 0; 1796 } 1797 1798 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1799 struct nameidata *nd) 1800 { 1801 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1802 } 1803 1804 /* 1805 * Link a file.. 1806 */ 1807 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1808 { 1809 struct inode *inode = old_dentry->d_inode; 1810 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1811 1812 /* 1813 * No ordinary (disk based) filesystem counts links as inodes; 1814 * but each new link needs a new dentry, pinning lowmem, and 1815 * tmpfs dentries cannot be pruned until they are unlinked. 1816 */ 1817 if (sbinfo->max_inodes) { 1818 spin_lock(&sbinfo->stat_lock); 1819 if (!sbinfo->free_inodes) { 1820 spin_unlock(&sbinfo->stat_lock); 1821 return -ENOSPC; 1822 } 1823 sbinfo->free_inodes--; 1824 spin_unlock(&sbinfo->stat_lock); 1825 } 1826 1827 dir->i_size += BOGO_DIRENT_SIZE; 1828 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1829 inc_nlink(inode); 1830 atomic_inc(&inode->i_count); /* New dentry reference */ 1831 dget(dentry); /* Extra pinning count for the created dentry */ 1832 d_instantiate(dentry, inode); 1833 return 0; 1834 } 1835 1836 static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1837 { 1838 struct inode *inode = dentry->d_inode; 1839 1840 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1841 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1842 if (sbinfo->max_inodes) { 1843 spin_lock(&sbinfo->stat_lock); 1844 sbinfo->free_inodes++; 1845 spin_unlock(&sbinfo->stat_lock); 1846 } 1847 } 1848 1849 dir->i_size -= BOGO_DIRENT_SIZE; 1850 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1851 drop_nlink(inode); 1852 dput(dentry); /* Undo the count from "create" - this does all the work */ 1853 return 0; 1854 } 1855 1856 static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1857 { 1858 if (!simple_empty(dentry)) 1859 return -ENOTEMPTY; 1860 1861 drop_nlink(dentry->d_inode); 1862 drop_nlink(dir); 1863 return shmem_unlink(dir, dentry); 1864 } 1865 1866 /* 1867 * The VFS layer already does all the dentry stuff for rename, 1868 * we just have to decrement the usage count for the target if 1869 * it exists so that the VFS layer correctly free's it when it 1870 * gets overwritten. 1871 */ 1872 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1873 { 1874 struct inode *inode = old_dentry->d_inode; 1875 int they_are_dirs = S_ISDIR(inode->i_mode); 1876 1877 if (!simple_empty(new_dentry)) 1878 return -ENOTEMPTY; 1879 1880 if (new_dentry->d_inode) { 1881 (void) shmem_unlink(new_dir, new_dentry); 1882 if (they_are_dirs) 1883 drop_nlink(old_dir); 1884 } else if (they_are_dirs) { 1885 drop_nlink(old_dir); 1886 inc_nlink(new_dir); 1887 } 1888 1889 old_dir->i_size -= BOGO_DIRENT_SIZE; 1890 new_dir->i_size += BOGO_DIRENT_SIZE; 1891 old_dir->i_ctime = old_dir->i_mtime = 1892 new_dir->i_ctime = new_dir->i_mtime = 1893 inode->i_ctime = CURRENT_TIME; 1894 return 0; 1895 } 1896 1897 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1898 { 1899 int error; 1900 int len; 1901 struct inode *inode; 1902 struct page *page = NULL; 1903 char *kaddr; 1904 struct shmem_inode_info *info; 1905 1906 len = strlen(symname) + 1; 1907 if (len > PAGE_CACHE_SIZE) 1908 return -ENAMETOOLONG; 1909 1910 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1911 if (!inode) 1912 return -ENOSPC; 1913 1914 error = security_inode_init_security(inode, dir, NULL, NULL, 1915 NULL); 1916 if (error) { 1917 if (error != -EOPNOTSUPP) { 1918 iput(inode); 1919 return error; 1920 } 1921 error = 0; 1922 } 1923 1924 info = SHMEM_I(inode); 1925 inode->i_size = len-1; 1926 if (len <= (char *)inode - (char *)info) { 1927 /* do it inline */ 1928 memcpy(info, symname, len); 1929 inode->i_op = &shmem_symlink_inline_operations; 1930 } else { 1931 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1932 if (error) { 1933 iput(inode); 1934 return error; 1935 } 1936 inode->i_op = &shmem_symlink_inode_operations; 1937 kaddr = kmap_atomic(page, KM_USER0); 1938 memcpy(kaddr, symname, len); 1939 kunmap_atomic(kaddr, KM_USER0); 1940 set_page_dirty(page); 1941 page_cache_release(page); 1942 } 1943 if (dir->i_mode & S_ISGID) 1944 inode->i_gid = dir->i_gid; 1945 dir->i_size += BOGO_DIRENT_SIZE; 1946 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1947 d_instantiate(dentry, inode); 1948 dget(dentry); 1949 return 0; 1950 } 1951 1952 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1953 { 1954 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1955 return NULL; 1956 } 1957 1958 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1959 { 1960 struct page *page = NULL; 1961 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1962 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1963 return page; 1964 } 1965 1966 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1967 { 1968 if (!IS_ERR(nd_get_link(nd))) { 1969 struct page *page = cookie; 1970 kunmap(page); 1971 mark_page_accessed(page); 1972 page_cache_release(page); 1973 } 1974 } 1975 1976 static const struct inode_operations shmem_symlink_inline_operations = { 1977 .readlink = generic_readlink, 1978 .follow_link = shmem_follow_link_inline, 1979 }; 1980 1981 static const struct inode_operations shmem_symlink_inode_operations = { 1982 .truncate = shmem_truncate, 1983 .readlink = generic_readlink, 1984 .follow_link = shmem_follow_link, 1985 .put_link = shmem_put_link, 1986 }; 1987 1988 #ifdef CONFIG_TMPFS_POSIX_ACL 1989 /** 1990 * Superblocks without xattr inode operations will get security.* xattr 1991 * support from the VFS "for free". As soon as we have any other xattrs 1992 * like ACLs, we also need to implement the security.* handlers at 1993 * filesystem level, though. 1994 */ 1995 1996 static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1997 size_t list_len, const char *name, 1998 size_t name_len) 1999 { 2000 return security_inode_listsecurity(inode, list, list_len); 2001 } 2002 2003 static int shmem_xattr_security_get(struct inode *inode, const char *name, 2004 void *buffer, size_t size) 2005 { 2006 if (strcmp(name, "") == 0) 2007 return -EINVAL; 2008 return security_inode_getsecurity(inode, name, buffer, size, 2009 -EOPNOTSUPP); 2010 } 2011 2012 static int shmem_xattr_security_set(struct inode *inode, const char *name, 2013 const void *value, size_t size, int flags) 2014 { 2015 if (strcmp(name, "") == 0) 2016 return -EINVAL; 2017 return security_inode_setsecurity(inode, name, value, size, flags); 2018 } 2019 2020 static struct xattr_handler shmem_xattr_security_handler = { 2021 .prefix = XATTR_SECURITY_PREFIX, 2022 .list = shmem_xattr_security_list, 2023 .get = shmem_xattr_security_get, 2024 .set = shmem_xattr_security_set, 2025 }; 2026 2027 static struct xattr_handler *shmem_xattr_handlers[] = { 2028 &shmem_xattr_acl_access_handler, 2029 &shmem_xattr_acl_default_handler, 2030 &shmem_xattr_security_handler, 2031 NULL 2032 }; 2033 #endif 2034 2035 static struct dentry *shmem_get_parent(struct dentry *child) 2036 { 2037 return ERR_PTR(-ESTALE); 2038 } 2039 2040 static int shmem_match(struct inode *ino, void *vfh) 2041 { 2042 __u32 *fh = vfh; 2043 __u64 inum = fh[2]; 2044 inum = (inum << 32) | fh[1]; 2045 return ino->i_ino == inum && fh[0] == ino->i_generation; 2046 } 2047 2048 static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh) 2049 { 2050 struct dentry *de = NULL; 2051 struct inode *inode; 2052 __u32 *fh = vfh; 2053 __u64 inum = fh[2]; 2054 inum = (inum << 32) | fh[1]; 2055 2056 inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh); 2057 if (inode) { 2058 de = d_find_alias(inode); 2059 iput(inode); 2060 } 2061 2062 return de? de: ERR_PTR(-ESTALE); 2063 } 2064 2065 static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh, 2066 int len, int type, 2067 int (*acceptable)(void *context, struct dentry *de), 2068 void *context) 2069 { 2070 if (len < 3) 2071 return ERR_PTR(-ESTALE); 2072 2073 return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable, 2074 context); 2075 } 2076 2077 static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2078 int connectable) 2079 { 2080 struct inode *inode = dentry->d_inode; 2081 2082 if (*len < 3) 2083 return 255; 2084 2085 if (hlist_unhashed(&inode->i_hash)) { 2086 /* Unfortunately insert_inode_hash is not idempotent, 2087 * so as we hash inodes here rather than at creation 2088 * time, we need a lock to ensure we only try 2089 * to do it once 2090 */ 2091 static DEFINE_SPINLOCK(lock); 2092 spin_lock(&lock); 2093 if (hlist_unhashed(&inode->i_hash)) 2094 __insert_inode_hash(inode, 2095 inode->i_ino + inode->i_generation); 2096 spin_unlock(&lock); 2097 } 2098 2099 fh[0] = inode->i_generation; 2100 fh[1] = inode->i_ino; 2101 fh[2] = ((__u64)inode->i_ino) >> 32; 2102 2103 *len = 3; 2104 return 1; 2105 } 2106 2107 static struct export_operations shmem_export_ops = { 2108 .get_parent = shmem_get_parent, 2109 .get_dentry = shmem_get_dentry, 2110 .encode_fh = shmem_encode_fh, 2111 .decode_fh = shmem_decode_fh, 2112 }; 2113 2114 static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2115 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2116 int *policy, nodemask_t *policy_nodes) 2117 { 2118 char *this_char, *value, *rest; 2119 2120 while (options != NULL) { 2121 this_char = options; 2122 for (;;) { 2123 /* 2124 * NUL-terminate this option: unfortunately, 2125 * mount options form a comma-separated list, 2126 * but mpol's nodelist may also contain commas. 2127 */ 2128 options = strchr(options, ','); 2129 if (options == NULL) 2130 break; 2131 options++; 2132 if (!isdigit(*options)) { 2133 options[-1] = '\0'; 2134 break; 2135 } 2136 } 2137 if (!*this_char) 2138 continue; 2139 if ((value = strchr(this_char,'=')) != NULL) { 2140 *value++ = 0; 2141 } else { 2142 printk(KERN_ERR 2143 "tmpfs: No value for mount option '%s'\n", 2144 this_char); 2145 return 1; 2146 } 2147 2148 if (!strcmp(this_char,"size")) { 2149 unsigned long long size; 2150 size = memparse(value,&rest); 2151 if (*rest == '%') { 2152 size <<= PAGE_SHIFT; 2153 size *= totalram_pages; 2154 do_div(size, 100); 2155 rest++; 2156 } 2157 if (*rest) 2158 goto bad_val; 2159 *blocks = size >> PAGE_CACHE_SHIFT; 2160 } else if (!strcmp(this_char,"nr_blocks")) { 2161 *blocks = memparse(value,&rest); 2162 if (*rest) 2163 goto bad_val; 2164 } else if (!strcmp(this_char,"nr_inodes")) { 2165 *inodes = memparse(value,&rest); 2166 if (*rest) 2167 goto bad_val; 2168 } else if (!strcmp(this_char,"mode")) { 2169 if (!mode) 2170 continue; 2171 *mode = simple_strtoul(value,&rest,8); 2172 if (*rest) 2173 goto bad_val; 2174 } else if (!strcmp(this_char,"uid")) { 2175 if (!uid) 2176 continue; 2177 *uid = simple_strtoul(value,&rest,0); 2178 if (*rest) 2179 goto bad_val; 2180 } else if (!strcmp(this_char,"gid")) { 2181 if (!gid) 2182 continue; 2183 *gid = simple_strtoul(value,&rest,0); 2184 if (*rest) 2185 goto bad_val; 2186 } else if (!strcmp(this_char,"mpol")) { 2187 if (shmem_parse_mpol(value,policy,policy_nodes)) 2188 goto bad_val; 2189 } else { 2190 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2191 this_char); 2192 return 1; 2193 } 2194 } 2195 return 0; 2196 2197 bad_val: 2198 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2199 value, this_char); 2200 return 1; 2201 2202 } 2203 2204 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2205 { 2206 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2207 unsigned long max_blocks = sbinfo->max_blocks; 2208 unsigned long max_inodes = sbinfo->max_inodes; 2209 int policy = sbinfo->policy; 2210 nodemask_t policy_nodes = sbinfo->policy_nodes; 2211 unsigned long blocks; 2212 unsigned long inodes; 2213 int error = -EINVAL; 2214 2215 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2216 &max_inodes, &policy, &policy_nodes)) 2217 return error; 2218 2219 spin_lock(&sbinfo->stat_lock); 2220 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2221 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2222 if (max_blocks < blocks) 2223 goto out; 2224 if (max_inodes < inodes) 2225 goto out; 2226 /* 2227 * Those tests also disallow limited->unlimited while any are in 2228 * use, so i_blocks will always be zero when max_blocks is zero; 2229 * but we must separately disallow unlimited->limited, because 2230 * in that case we have no record of how much is already in use. 2231 */ 2232 if (max_blocks && !sbinfo->max_blocks) 2233 goto out; 2234 if (max_inodes && !sbinfo->max_inodes) 2235 goto out; 2236 2237 error = 0; 2238 sbinfo->max_blocks = max_blocks; 2239 sbinfo->free_blocks = max_blocks - blocks; 2240 sbinfo->max_inodes = max_inodes; 2241 sbinfo->free_inodes = max_inodes - inodes; 2242 sbinfo->policy = policy; 2243 sbinfo->policy_nodes = policy_nodes; 2244 out: 2245 spin_unlock(&sbinfo->stat_lock); 2246 return error; 2247 } 2248 #endif 2249 2250 static void shmem_put_super(struct super_block *sb) 2251 { 2252 kfree(sb->s_fs_info); 2253 sb->s_fs_info = NULL; 2254 } 2255 2256 static int shmem_fill_super(struct super_block *sb, 2257 void *data, int silent) 2258 { 2259 struct inode *inode; 2260 struct dentry *root; 2261 int mode = S_IRWXUGO | S_ISVTX; 2262 uid_t uid = current->fsuid; 2263 gid_t gid = current->fsgid; 2264 int err = -ENOMEM; 2265 struct shmem_sb_info *sbinfo; 2266 unsigned long blocks = 0; 2267 unsigned long inodes = 0; 2268 int policy = MPOL_DEFAULT; 2269 nodemask_t policy_nodes = node_online_map; 2270 2271 #ifdef CONFIG_TMPFS 2272 /* 2273 * Per default we only allow half of the physical ram per 2274 * tmpfs instance, limiting inodes to one per page of lowmem; 2275 * but the internal instance is left unlimited. 2276 */ 2277 if (!(sb->s_flags & MS_NOUSER)) { 2278 blocks = totalram_pages / 2; 2279 inodes = totalram_pages - totalhigh_pages; 2280 if (inodes > blocks) 2281 inodes = blocks; 2282 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2283 &inodes, &policy, &policy_nodes)) 2284 return -EINVAL; 2285 } 2286 sb->s_export_op = &shmem_export_ops; 2287 #else 2288 sb->s_flags |= MS_NOUSER; 2289 #endif 2290 2291 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2292 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2293 L1_CACHE_BYTES), GFP_KERNEL); 2294 if (!sbinfo) 2295 return -ENOMEM; 2296 2297 spin_lock_init(&sbinfo->stat_lock); 2298 sbinfo->max_blocks = blocks; 2299 sbinfo->free_blocks = blocks; 2300 sbinfo->max_inodes = inodes; 2301 sbinfo->free_inodes = inodes; 2302 sbinfo->policy = policy; 2303 sbinfo->policy_nodes = policy_nodes; 2304 2305 sb->s_fs_info = sbinfo; 2306 sb->s_maxbytes = SHMEM_MAX_BYTES; 2307 sb->s_blocksize = PAGE_CACHE_SIZE; 2308 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2309 sb->s_magic = TMPFS_MAGIC; 2310 sb->s_op = &shmem_ops; 2311 sb->s_time_gran = 1; 2312 #ifdef CONFIG_TMPFS_POSIX_ACL 2313 sb->s_xattr = shmem_xattr_handlers; 2314 sb->s_flags |= MS_POSIXACL; 2315 #endif 2316 2317 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2318 if (!inode) 2319 goto failed; 2320 inode->i_uid = uid; 2321 inode->i_gid = gid; 2322 root = d_alloc_root(inode); 2323 if (!root) 2324 goto failed_iput; 2325 sb->s_root = root; 2326 return 0; 2327 2328 failed_iput: 2329 iput(inode); 2330 failed: 2331 shmem_put_super(sb); 2332 return err; 2333 } 2334 2335 static struct kmem_cache *shmem_inode_cachep; 2336 2337 static struct inode *shmem_alloc_inode(struct super_block *sb) 2338 { 2339 struct shmem_inode_info *p; 2340 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2341 if (!p) 2342 return NULL; 2343 return &p->vfs_inode; 2344 } 2345 2346 static void shmem_destroy_inode(struct inode *inode) 2347 { 2348 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2349 /* only struct inode is valid if it's an inline symlink */ 2350 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2351 } 2352 shmem_acl_destroy_inode(inode); 2353 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2354 } 2355 2356 static void init_once(void *foo, struct kmem_cache *cachep, 2357 unsigned long flags) 2358 { 2359 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2360 2361 if (flags & SLAB_CTOR_CONSTRUCTOR) { 2362 inode_init_once(&p->vfs_inode); 2363 #ifdef CONFIG_TMPFS_POSIX_ACL 2364 p->i_acl = NULL; 2365 p->i_default_acl = NULL; 2366 #endif 2367 } 2368 } 2369 2370 static int init_inodecache(void) 2371 { 2372 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2373 sizeof(struct shmem_inode_info), 2374 0, 0, init_once, NULL); 2375 if (shmem_inode_cachep == NULL) 2376 return -ENOMEM; 2377 return 0; 2378 } 2379 2380 static void destroy_inodecache(void) 2381 { 2382 kmem_cache_destroy(shmem_inode_cachep); 2383 } 2384 2385 static const struct address_space_operations shmem_aops = { 2386 .writepage = shmem_writepage, 2387 .set_page_dirty = __set_page_dirty_no_writeback, 2388 #ifdef CONFIG_TMPFS 2389 .prepare_write = shmem_prepare_write, 2390 .commit_write = simple_commit_write, 2391 #endif 2392 .migratepage = migrate_page, 2393 }; 2394 2395 static const struct file_operations shmem_file_operations = { 2396 .mmap = shmem_mmap, 2397 #ifdef CONFIG_TMPFS 2398 .llseek = generic_file_llseek, 2399 .read = shmem_file_read, 2400 .write = shmem_file_write, 2401 .fsync = simple_sync_file, 2402 .sendfile = shmem_file_sendfile, 2403 #endif 2404 }; 2405 2406 static const struct inode_operations shmem_inode_operations = { 2407 .truncate = shmem_truncate, 2408 .setattr = shmem_notify_change, 2409 .truncate_range = shmem_truncate_range, 2410 #ifdef CONFIG_TMPFS_POSIX_ACL 2411 .setxattr = generic_setxattr, 2412 .getxattr = generic_getxattr, 2413 .listxattr = generic_listxattr, 2414 .removexattr = generic_removexattr, 2415 .permission = shmem_permission, 2416 #endif 2417 2418 }; 2419 2420 static const struct inode_operations shmem_dir_inode_operations = { 2421 #ifdef CONFIG_TMPFS 2422 .create = shmem_create, 2423 .lookup = simple_lookup, 2424 .link = shmem_link, 2425 .unlink = shmem_unlink, 2426 .symlink = shmem_symlink, 2427 .mkdir = shmem_mkdir, 2428 .rmdir = shmem_rmdir, 2429 .mknod = shmem_mknod, 2430 .rename = shmem_rename, 2431 #endif 2432 #ifdef CONFIG_TMPFS_POSIX_ACL 2433 .setattr = shmem_notify_change, 2434 .setxattr = generic_setxattr, 2435 .getxattr = generic_getxattr, 2436 .listxattr = generic_listxattr, 2437 .removexattr = generic_removexattr, 2438 .permission = shmem_permission, 2439 #endif 2440 }; 2441 2442 static const struct inode_operations shmem_special_inode_operations = { 2443 #ifdef CONFIG_TMPFS_POSIX_ACL 2444 .setattr = shmem_notify_change, 2445 .setxattr = generic_setxattr, 2446 .getxattr = generic_getxattr, 2447 .listxattr = generic_listxattr, 2448 .removexattr = generic_removexattr, 2449 .permission = shmem_permission, 2450 #endif 2451 }; 2452 2453 static const struct super_operations shmem_ops = { 2454 .alloc_inode = shmem_alloc_inode, 2455 .destroy_inode = shmem_destroy_inode, 2456 #ifdef CONFIG_TMPFS 2457 .statfs = shmem_statfs, 2458 .remount_fs = shmem_remount_fs, 2459 #endif 2460 .delete_inode = shmem_delete_inode, 2461 .drop_inode = generic_delete_inode, 2462 .put_super = shmem_put_super, 2463 }; 2464 2465 static struct vm_operations_struct shmem_vm_ops = { 2466 .nopage = shmem_nopage, 2467 .populate = shmem_populate, 2468 #ifdef CONFIG_NUMA 2469 .set_policy = shmem_set_policy, 2470 .get_policy = shmem_get_policy, 2471 #endif 2472 }; 2473 2474 2475 static int shmem_get_sb(struct file_system_type *fs_type, 2476 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2477 { 2478 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2479 } 2480 2481 static struct file_system_type tmpfs_fs_type = { 2482 .owner = THIS_MODULE, 2483 .name = "tmpfs", 2484 .get_sb = shmem_get_sb, 2485 .kill_sb = kill_litter_super, 2486 }; 2487 static struct vfsmount *shm_mnt; 2488 2489 static int __init init_tmpfs(void) 2490 { 2491 int error; 2492 2493 error = init_inodecache(); 2494 if (error) 2495 goto out3; 2496 2497 error = register_filesystem(&tmpfs_fs_type); 2498 if (error) { 2499 printk(KERN_ERR "Could not register tmpfs\n"); 2500 goto out2; 2501 } 2502 2503 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2504 tmpfs_fs_type.name, NULL); 2505 if (IS_ERR(shm_mnt)) { 2506 error = PTR_ERR(shm_mnt); 2507 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2508 goto out1; 2509 } 2510 return 0; 2511 2512 out1: 2513 unregister_filesystem(&tmpfs_fs_type); 2514 out2: 2515 destroy_inodecache(); 2516 out3: 2517 shm_mnt = ERR_PTR(error); 2518 return error; 2519 } 2520 module_init(init_tmpfs) 2521 2522 /* 2523 * shmem_file_setup - get an unlinked file living in tmpfs 2524 * 2525 * @name: name for dentry (to be seen in /proc/<pid>/maps 2526 * @size: size to be set for the file 2527 * 2528 */ 2529 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2530 { 2531 int error; 2532 struct file *file; 2533 struct inode *inode; 2534 struct dentry *dentry, *root; 2535 struct qstr this; 2536 2537 if (IS_ERR(shm_mnt)) 2538 return (void *)shm_mnt; 2539 2540 if (size < 0 || size > SHMEM_MAX_BYTES) 2541 return ERR_PTR(-EINVAL); 2542 2543 if (shmem_acct_size(flags, size)) 2544 return ERR_PTR(-ENOMEM); 2545 2546 error = -ENOMEM; 2547 this.name = name; 2548 this.len = strlen(name); 2549 this.hash = 0; /* will go */ 2550 root = shm_mnt->mnt_root; 2551 dentry = d_alloc(root, &this); 2552 if (!dentry) 2553 goto put_memory; 2554 2555 error = -ENFILE; 2556 file = get_empty_filp(); 2557 if (!file) 2558 goto put_dentry; 2559 2560 error = -ENOSPC; 2561 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2562 if (!inode) 2563 goto close_file; 2564 2565 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2566 d_instantiate(dentry, inode); 2567 inode->i_size = size; 2568 inode->i_nlink = 0; /* It is unlinked */ 2569 file->f_path.mnt = mntget(shm_mnt); 2570 file->f_path.dentry = dentry; 2571 file->f_mapping = inode->i_mapping; 2572 file->f_op = &shmem_file_operations; 2573 file->f_mode = FMODE_WRITE | FMODE_READ; 2574 return file; 2575 2576 close_file: 2577 put_filp(file); 2578 put_dentry: 2579 dput(dentry); 2580 put_memory: 2581 shmem_unacct_size(flags, size); 2582 return ERR_PTR(error); 2583 } 2584 2585 /* 2586 * shmem_zero_setup - setup a shared anonymous mapping 2587 * 2588 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2589 */ 2590 int shmem_zero_setup(struct vm_area_struct *vma) 2591 { 2592 struct file *file; 2593 loff_t size = vma->vm_end - vma->vm_start; 2594 2595 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2596 if (IS_ERR(file)) 2597 return PTR_ERR(file); 2598 2599 if (vma->vm_file) 2600 fput(vma->vm_file); 2601 vma->vm_file = file; 2602 vma->vm_ops = &shmem_vm_ops; 2603 return 0; 2604 } 2605