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/config.h> 27 #include <linux/module.h> 28 #include <linux/init.h> 29 #include <linux/devfs_fs_kernel.h> 30 #include <linux/fs.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 <asm/uaccess.h> 49 #include <asm/div64.h> 50 #include <asm/pgtable.h> 51 52 /* This magic number is used in glibc for posix shared memory */ 53 #define TMPFS_MAGIC 0x01021994 54 55 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 56 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 57 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 58 59 #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 60 #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 61 62 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 63 64 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 65 #define SHMEM_PAGEIN VM_READ 66 #define SHMEM_TRUNCATE VM_WRITE 67 68 /* Definition to limit shmem_truncate's steps between cond_rescheds */ 69 #define LATENCY_LIMIT 64 70 71 /* Pretend that each entry is of this size in directory's i_size */ 72 #define BOGO_DIRENT_SIZE 20 73 74 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 75 enum sgp_type { 76 SGP_QUICK, /* don't try more than file page cache lookup */ 77 SGP_READ, /* don't exceed i_size, don't allocate page */ 78 SGP_CACHE, /* don't exceed i_size, may allocate page */ 79 SGP_WRITE, /* may exceed i_size, may allocate page */ 80 }; 81 82 static int shmem_getpage(struct inode *inode, unsigned long idx, 83 struct page **pagep, enum sgp_type sgp, int *type); 84 85 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 86 { 87 /* 88 * The above definition of ENTRIES_PER_PAGE, and the use of 89 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 90 * might be reconsidered if it ever diverges from PAGE_SIZE. 91 */ 92 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); 93 } 94 95 static inline void shmem_dir_free(struct page *page) 96 { 97 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 98 } 99 100 static struct page **shmem_dir_map(struct page *page) 101 { 102 return (struct page **)kmap_atomic(page, KM_USER0); 103 } 104 105 static inline void shmem_dir_unmap(struct page **dir) 106 { 107 kunmap_atomic(dir, KM_USER0); 108 } 109 110 static swp_entry_t *shmem_swp_map(struct page *page) 111 { 112 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 113 } 114 115 static inline void shmem_swp_balance_unmap(void) 116 { 117 /* 118 * When passing a pointer to an i_direct entry, to code which 119 * also handles indirect entries and so will shmem_swp_unmap, 120 * we must arrange for the preempt count to remain in balance. 121 * What kmap_atomic of a lowmem page does depends on config 122 * and architecture, so pretend to kmap_atomic some lowmem page. 123 */ 124 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 125 } 126 127 static inline void shmem_swp_unmap(swp_entry_t *entry) 128 { 129 kunmap_atomic(entry, KM_USER1); 130 } 131 132 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 133 { 134 return sb->s_fs_info; 135 } 136 137 /* 138 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 139 * for shared memory and for shared anonymous (/dev/zero) mappings 140 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 141 * consistent with the pre-accounting of private mappings ... 142 */ 143 static inline int shmem_acct_size(unsigned long flags, loff_t size) 144 { 145 return (flags & VM_ACCOUNT)? 146 security_vm_enough_memory(VM_ACCT(size)): 0; 147 } 148 149 static inline void shmem_unacct_size(unsigned long flags, loff_t size) 150 { 151 if (flags & VM_ACCOUNT) 152 vm_unacct_memory(VM_ACCT(size)); 153 } 154 155 /* 156 * ... whereas tmpfs objects are accounted incrementally as 157 * pages are allocated, in order to allow huge sparse files. 158 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 159 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 160 */ 161 static inline int shmem_acct_block(unsigned long flags) 162 { 163 return (flags & VM_ACCOUNT)? 164 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 165 } 166 167 static inline void shmem_unacct_blocks(unsigned long flags, long pages) 168 { 169 if (!(flags & VM_ACCOUNT)) 170 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 171 } 172 173 static struct super_operations shmem_ops; 174 static struct address_space_operations shmem_aops; 175 static struct file_operations shmem_file_operations; 176 static struct inode_operations shmem_inode_operations; 177 static struct inode_operations shmem_dir_inode_operations; 178 static struct vm_operations_struct shmem_vm_ops; 179 180 static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 181 .ra_pages = 0, /* No readahead */ 182 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 183 .unplug_io_fn = default_unplug_io_fn, 184 }; 185 186 static LIST_HEAD(shmem_swaplist); 187 static DEFINE_SPINLOCK(shmem_swaplist_lock); 188 189 static void shmem_free_blocks(struct inode *inode, long pages) 190 { 191 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 192 if (sbinfo->max_blocks) { 193 spin_lock(&sbinfo->stat_lock); 194 sbinfo->free_blocks += pages; 195 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 196 spin_unlock(&sbinfo->stat_lock); 197 } 198 } 199 200 /* 201 * shmem_recalc_inode - recalculate the size of an inode 202 * 203 * @inode: inode to recalc 204 * 205 * We have to calculate the free blocks since the mm can drop 206 * undirtied hole pages behind our back. 207 * 208 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 209 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 210 * 211 * It has to be called with the spinlock held. 212 */ 213 static void shmem_recalc_inode(struct inode *inode) 214 { 215 struct shmem_inode_info *info = SHMEM_I(inode); 216 long freed; 217 218 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 219 if (freed > 0) { 220 info->alloced -= freed; 221 shmem_unacct_blocks(info->flags, freed); 222 shmem_free_blocks(inode, freed); 223 } 224 } 225 226 /* 227 * shmem_swp_entry - find the swap vector position in the info structure 228 * 229 * @info: info structure for the inode 230 * @index: index of the page to find 231 * @page: optional page to add to the structure. Has to be preset to 232 * all zeros 233 * 234 * If there is no space allocated yet it will return NULL when 235 * page is NULL, else it will use the page for the needed block, 236 * setting it to NULL on return to indicate that it has been used. 237 * 238 * The swap vector is organized the following way: 239 * 240 * There are SHMEM_NR_DIRECT entries directly stored in the 241 * shmem_inode_info structure. So small files do not need an addional 242 * allocation. 243 * 244 * For pages with index > SHMEM_NR_DIRECT there is the pointer 245 * i_indirect which points to a page which holds in the first half 246 * doubly indirect blocks, in the second half triple indirect blocks: 247 * 248 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 249 * following layout (for SHMEM_NR_DIRECT == 16): 250 * 251 * i_indirect -> dir --> 16-19 252 * | +-> 20-23 253 * | 254 * +-->dir2 --> 24-27 255 * | +-> 28-31 256 * | +-> 32-35 257 * | +-> 36-39 258 * | 259 * +-->dir3 --> 40-43 260 * +-> 44-47 261 * +-> 48-51 262 * +-> 52-55 263 */ 264 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 265 { 266 unsigned long offset; 267 struct page **dir; 268 struct page *subdir; 269 270 if (index < SHMEM_NR_DIRECT) { 271 shmem_swp_balance_unmap(); 272 return info->i_direct+index; 273 } 274 if (!info->i_indirect) { 275 if (page) { 276 info->i_indirect = *page; 277 *page = NULL; 278 } 279 return NULL; /* need another page */ 280 } 281 282 index -= SHMEM_NR_DIRECT; 283 offset = index % ENTRIES_PER_PAGE; 284 index /= ENTRIES_PER_PAGE; 285 dir = shmem_dir_map(info->i_indirect); 286 287 if (index >= ENTRIES_PER_PAGE/2) { 288 index -= ENTRIES_PER_PAGE/2; 289 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 290 index %= ENTRIES_PER_PAGE; 291 subdir = *dir; 292 if (!subdir) { 293 if (page) { 294 *dir = *page; 295 *page = NULL; 296 } 297 shmem_dir_unmap(dir); 298 return NULL; /* need another page */ 299 } 300 shmem_dir_unmap(dir); 301 dir = shmem_dir_map(subdir); 302 } 303 304 dir += index; 305 subdir = *dir; 306 if (!subdir) { 307 if (!page || !(subdir = *page)) { 308 shmem_dir_unmap(dir); 309 return NULL; /* need a page */ 310 } 311 *dir = subdir; 312 *page = NULL; 313 } 314 shmem_dir_unmap(dir); 315 return shmem_swp_map(subdir) + offset; 316 } 317 318 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 319 { 320 long incdec = value? 1: -1; 321 322 entry->val = value; 323 info->swapped += incdec; 324 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 325 struct page *page = kmap_atomic_to_page(entry); 326 set_page_private(page, page_private(page) + incdec); 327 } 328 } 329 330 /* 331 * shmem_swp_alloc - get the position of the swap entry for the page. 332 * If it does not exist allocate the entry. 333 * 334 * @info: info structure for the inode 335 * @index: index of the page to find 336 * @sgp: check and recheck i_size? skip allocation? 337 */ 338 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 339 { 340 struct inode *inode = &info->vfs_inode; 341 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 342 struct page *page = NULL; 343 swp_entry_t *entry; 344 345 if (sgp != SGP_WRITE && 346 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 347 return ERR_PTR(-EINVAL); 348 349 while (!(entry = shmem_swp_entry(info, index, &page))) { 350 if (sgp == SGP_READ) 351 return shmem_swp_map(ZERO_PAGE(0)); 352 /* 353 * Test free_blocks against 1 not 0, since we have 1 data 354 * page (and perhaps indirect index pages) yet to allocate: 355 * a waste to allocate index if we cannot allocate data. 356 */ 357 if (sbinfo->max_blocks) { 358 spin_lock(&sbinfo->stat_lock); 359 if (sbinfo->free_blocks <= 1) { 360 spin_unlock(&sbinfo->stat_lock); 361 return ERR_PTR(-ENOSPC); 362 } 363 sbinfo->free_blocks--; 364 inode->i_blocks += BLOCKS_PER_PAGE; 365 spin_unlock(&sbinfo->stat_lock); 366 } 367 368 spin_unlock(&info->lock); 369 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); 370 if (page) 371 set_page_private(page, 0); 372 spin_lock(&info->lock); 373 374 if (!page) { 375 shmem_free_blocks(inode, 1); 376 return ERR_PTR(-ENOMEM); 377 } 378 if (sgp != SGP_WRITE && 379 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 380 entry = ERR_PTR(-EINVAL); 381 break; 382 } 383 if (info->next_index <= index) 384 info->next_index = index + 1; 385 } 386 if (page) { 387 /* another task gave its page, or truncated the file */ 388 shmem_free_blocks(inode, 1); 389 shmem_dir_free(page); 390 } 391 if (info->next_index <= index && !IS_ERR(entry)) 392 info->next_index = index + 1; 393 return entry; 394 } 395 396 /* 397 * shmem_free_swp - free some swap entries in a directory 398 * 399 * @dir: pointer to the directory 400 * @edir: pointer after last entry of the directory 401 */ 402 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) 403 { 404 swp_entry_t *ptr; 405 int freed = 0; 406 407 for (ptr = dir; ptr < edir; ptr++) { 408 if (ptr->val) { 409 free_swap_and_cache(*ptr); 410 *ptr = (swp_entry_t){0}; 411 freed++; 412 } 413 } 414 return freed; 415 } 416 417 static int shmem_map_and_free_swp(struct page *subdir, 418 int offset, int limit, struct page ***dir) 419 { 420 swp_entry_t *ptr; 421 int freed = 0; 422 423 ptr = shmem_swp_map(subdir); 424 for (; offset < limit; offset += LATENCY_LIMIT) { 425 int size = limit - offset; 426 if (size > LATENCY_LIMIT) 427 size = LATENCY_LIMIT; 428 freed += shmem_free_swp(ptr+offset, ptr+offset+size); 429 if (need_resched()) { 430 shmem_swp_unmap(ptr); 431 if (*dir) { 432 shmem_dir_unmap(*dir); 433 *dir = NULL; 434 } 435 cond_resched(); 436 ptr = shmem_swp_map(subdir); 437 } 438 } 439 shmem_swp_unmap(ptr); 440 return freed; 441 } 442 443 static void shmem_free_pages(struct list_head *next) 444 { 445 struct page *page; 446 int freed = 0; 447 448 do { 449 page = container_of(next, struct page, lru); 450 next = next->next; 451 shmem_dir_free(page); 452 freed++; 453 if (freed >= LATENCY_LIMIT) { 454 cond_resched(); 455 freed = 0; 456 } 457 } while (next); 458 } 459 460 static void shmem_truncate(struct inode *inode) 461 { 462 struct shmem_inode_info *info = SHMEM_I(inode); 463 unsigned long idx; 464 unsigned long size; 465 unsigned long limit; 466 unsigned long stage; 467 unsigned long diroff; 468 struct page **dir; 469 struct page *topdir; 470 struct page *middir; 471 struct page *subdir; 472 swp_entry_t *ptr; 473 LIST_HEAD(pages_to_free); 474 long nr_pages_to_free = 0; 475 long nr_swaps_freed = 0; 476 int offset; 477 int freed; 478 479 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 480 idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 481 if (idx >= info->next_index) 482 return; 483 484 spin_lock(&info->lock); 485 info->flags |= SHMEM_TRUNCATE; 486 limit = info->next_index; 487 info->next_index = idx; 488 topdir = info->i_indirect; 489 if (topdir && idx <= SHMEM_NR_DIRECT) { 490 info->i_indirect = NULL; 491 nr_pages_to_free++; 492 list_add(&topdir->lru, &pages_to_free); 493 } 494 spin_unlock(&info->lock); 495 496 if (info->swapped && idx < SHMEM_NR_DIRECT) { 497 ptr = info->i_direct; 498 size = limit; 499 if (size > SHMEM_NR_DIRECT) 500 size = SHMEM_NR_DIRECT; 501 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size); 502 } 503 if (!topdir) 504 goto done2; 505 506 BUG_ON(limit <= SHMEM_NR_DIRECT); 507 limit -= SHMEM_NR_DIRECT; 508 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 509 offset = idx % ENTRIES_PER_PAGE; 510 idx -= offset; 511 512 dir = shmem_dir_map(topdir); 513 stage = ENTRIES_PER_PAGEPAGE/2; 514 if (idx < ENTRIES_PER_PAGEPAGE/2) { 515 middir = topdir; 516 diroff = idx/ENTRIES_PER_PAGE; 517 } else { 518 dir += ENTRIES_PER_PAGE/2; 519 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 520 while (stage <= idx) 521 stage += ENTRIES_PER_PAGEPAGE; 522 middir = *dir; 523 if (*dir) { 524 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 525 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 526 if (!diroff && !offset) { 527 *dir = NULL; 528 nr_pages_to_free++; 529 list_add(&middir->lru, &pages_to_free); 530 } 531 shmem_dir_unmap(dir); 532 dir = shmem_dir_map(middir); 533 } else { 534 diroff = 0; 535 offset = 0; 536 idx = stage; 537 } 538 } 539 540 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 541 if (unlikely(idx == stage)) { 542 shmem_dir_unmap(dir); 543 dir = shmem_dir_map(topdir) + 544 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 545 while (!*dir) { 546 dir++; 547 idx += ENTRIES_PER_PAGEPAGE; 548 if (idx >= limit) 549 goto done1; 550 } 551 stage = idx + ENTRIES_PER_PAGEPAGE; 552 middir = *dir; 553 *dir = NULL; 554 nr_pages_to_free++; 555 list_add(&middir->lru, &pages_to_free); 556 shmem_dir_unmap(dir); 557 cond_resched(); 558 dir = shmem_dir_map(middir); 559 diroff = 0; 560 } 561 subdir = dir[diroff]; 562 if (subdir && page_private(subdir)) { 563 size = limit - idx; 564 if (size > ENTRIES_PER_PAGE) 565 size = ENTRIES_PER_PAGE; 566 freed = shmem_map_and_free_swp(subdir, 567 offset, size, &dir); 568 if (!dir) 569 dir = shmem_dir_map(middir); 570 nr_swaps_freed += freed; 571 if (offset) 572 spin_lock(&info->lock); 573 set_page_private(subdir, page_private(subdir) - freed); 574 if (offset) 575 spin_unlock(&info->lock); 576 BUG_ON(page_private(subdir) > offset); 577 } 578 if (offset) 579 offset = 0; 580 else if (subdir) { 581 dir[diroff] = NULL; 582 nr_pages_to_free++; 583 list_add(&subdir->lru, &pages_to_free); 584 } 585 } 586 done1: 587 shmem_dir_unmap(dir); 588 done2: 589 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 590 /* 591 * Call truncate_inode_pages again: racing shmem_unuse_inode 592 * may have swizzled a page in from swap since vmtruncate or 593 * generic_delete_inode did it, before we lowered next_index. 594 * Also, though shmem_getpage checks i_size before adding to 595 * cache, no recheck after: so fix the narrow window there too. 596 */ 597 truncate_inode_pages(inode->i_mapping, inode->i_size); 598 } 599 600 spin_lock(&info->lock); 601 info->flags &= ~SHMEM_TRUNCATE; 602 info->swapped -= nr_swaps_freed; 603 if (nr_pages_to_free) 604 shmem_free_blocks(inode, nr_pages_to_free); 605 shmem_recalc_inode(inode); 606 spin_unlock(&info->lock); 607 608 /* 609 * Empty swap vector directory pages to be freed? 610 */ 611 if (!list_empty(&pages_to_free)) { 612 pages_to_free.prev->next = NULL; 613 shmem_free_pages(pages_to_free.next); 614 } 615 } 616 617 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 618 { 619 struct inode *inode = dentry->d_inode; 620 struct page *page = NULL; 621 int error; 622 623 if (attr->ia_valid & ATTR_SIZE) { 624 if (attr->ia_size < inode->i_size) { 625 /* 626 * If truncating down to a partial page, then 627 * if that page is already allocated, hold it 628 * in memory until the truncation is over, so 629 * truncate_partial_page cannnot miss it were 630 * it assigned to swap. 631 */ 632 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 633 (void) shmem_getpage(inode, 634 attr->ia_size>>PAGE_CACHE_SHIFT, 635 &page, SGP_READ, NULL); 636 } 637 /* 638 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 639 * detect if any pages might have been added to cache 640 * after truncate_inode_pages. But we needn't bother 641 * if it's being fully truncated to zero-length: the 642 * nrpages check is efficient enough in that case. 643 */ 644 if (attr->ia_size) { 645 struct shmem_inode_info *info = SHMEM_I(inode); 646 spin_lock(&info->lock); 647 info->flags &= ~SHMEM_PAGEIN; 648 spin_unlock(&info->lock); 649 } 650 } 651 } 652 653 error = inode_change_ok(inode, attr); 654 if (!error) 655 error = inode_setattr(inode, attr); 656 if (page) 657 page_cache_release(page); 658 return error; 659 } 660 661 static void shmem_delete_inode(struct inode *inode) 662 { 663 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 664 struct shmem_inode_info *info = SHMEM_I(inode); 665 666 if (inode->i_op->truncate == shmem_truncate) { 667 truncate_inode_pages(inode->i_mapping, 0); 668 shmem_unacct_size(info->flags, inode->i_size); 669 inode->i_size = 0; 670 shmem_truncate(inode); 671 if (!list_empty(&info->swaplist)) { 672 spin_lock(&shmem_swaplist_lock); 673 list_del_init(&info->swaplist); 674 spin_unlock(&shmem_swaplist_lock); 675 } 676 } 677 BUG_ON(inode->i_blocks); 678 if (sbinfo->max_inodes) { 679 spin_lock(&sbinfo->stat_lock); 680 sbinfo->free_inodes++; 681 spin_unlock(&sbinfo->stat_lock); 682 } 683 clear_inode(inode); 684 } 685 686 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 687 { 688 swp_entry_t *ptr; 689 690 for (ptr = dir; ptr < edir; ptr++) { 691 if (ptr->val == entry.val) 692 return ptr - dir; 693 } 694 return -1; 695 } 696 697 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 698 { 699 struct inode *inode; 700 unsigned long idx; 701 unsigned long size; 702 unsigned long limit; 703 unsigned long stage; 704 struct page **dir; 705 struct page *subdir; 706 swp_entry_t *ptr; 707 int offset; 708 709 idx = 0; 710 ptr = info->i_direct; 711 spin_lock(&info->lock); 712 limit = info->next_index; 713 size = limit; 714 if (size > SHMEM_NR_DIRECT) 715 size = SHMEM_NR_DIRECT; 716 offset = shmem_find_swp(entry, ptr, ptr+size); 717 if (offset >= 0) { 718 shmem_swp_balance_unmap(); 719 goto found; 720 } 721 if (!info->i_indirect) 722 goto lost2; 723 724 dir = shmem_dir_map(info->i_indirect); 725 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 726 727 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 728 if (unlikely(idx == stage)) { 729 shmem_dir_unmap(dir-1); 730 dir = shmem_dir_map(info->i_indirect) + 731 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 732 while (!*dir) { 733 dir++; 734 idx += ENTRIES_PER_PAGEPAGE; 735 if (idx >= limit) 736 goto lost1; 737 } 738 stage = idx + ENTRIES_PER_PAGEPAGE; 739 subdir = *dir; 740 shmem_dir_unmap(dir); 741 dir = shmem_dir_map(subdir); 742 } 743 subdir = *dir; 744 if (subdir && page_private(subdir)) { 745 ptr = shmem_swp_map(subdir); 746 size = limit - idx; 747 if (size > ENTRIES_PER_PAGE) 748 size = ENTRIES_PER_PAGE; 749 offset = shmem_find_swp(entry, ptr, ptr+size); 750 if (offset >= 0) { 751 shmem_dir_unmap(dir); 752 goto found; 753 } 754 shmem_swp_unmap(ptr); 755 } 756 } 757 lost1: 758 shmem_dir_unmap(dir-1); 759 lost2: 760 spin_unlock(&info->lock); 761 return 0; 762 found: 763 idx += offset; 764 inode = &info->vfs_inode; 765 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 766 info->flags |= SHMEM_PAGEIN; 767 shmem_swp_set(info, ptr + offset, 0); 768 } 769 shmem_swp_unmap(ptr); 770 spin_unlock(&info->lock); 771 /* 772 * Decrement swap count even when the entry is left behind: 773 * try_to_unuse will skip over mms, then reincrement count. 774 */ 775 swap_free(entry); 776 return 1; 777 } 778 779 /* 780 * shmem_unuse() search for an eventually swapped out shmem page. 781 */ 782 int shmem_unuse(swp_entry_t entry, struct page *page) 783 { 784 struct list_head *p, *next; 785 struct shmem_inode_info *info; 786 int found = 0; 787 788 spin_lock(&shmem_swaplist_lock); 789 list_for_each_safe(p, next, &shmem_swaplist) { 790 info = list_entry(p, struct shmem_inode_info, swaplist); 791 if (!info->swapped) 792 list_del_init(&info->swaplist); 793 else if (shmem_unuse_inode(info, entry, page)) { 794 /* move head to start search for next from here */ 795 list_move_tail(&shmem_swaplist, &info->swaplist); 796 found = 1; 797 break; 798 } 799 } 800 spin_unlock(&shmem_swaplist_lock); 801 return found; 802 } 803 804 /* 805 * Move the page from the page cache to the swap cache. 806 */ 807 static int shmem_writepage(struct page *page, struct writeback_control *wbc) 808 { 809 struct shmem_inode_info *info; 810 swp_entry_t *entry, swap; 811 struct address_space *mapping; 812 unsigned long index; 813 struct inode *inode; 814 815 BUG_ON(!PageLocked(page)); 816 BUG_ON(page_mapped(page)); 817 818 mapping = page->mapping; 819 index = page->index; 820 inode = mapping->host; 821 info = SHMEM_I(inode); 822 if (info->flags & VM_LOCKED) 823 goto redirty; 824 swap = get_swap_page(); 825 if (!swap.val) 826 goto redirty; 827 828 spin_lock(&info->lock); 829 shmem_recalc_inode(inode); 830 if (index >= info->next_index) { 831 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 832 goto unlock; 833 } 834 entry = shmem_swp_entry(info, index, NULL); 835 BUG_ON(!entry); 836 BUG_ON(entry->val); 837 838 if (move_to_swap_cache(page, swap) == 0) { 839 shmem_swp_set(info, entry, swap.val); 840 shmem_swp_unmap(entry); 841 spin_unlock(&info->lock); 842 if (list_empty(&info->swaplist)) { 843 spin_lock(&shmem_swaplist_lock); 844 /* move instead of add in case we're racing */ 845 list_move_tail(&info->swaplist, &shmem_swaplist); 846 spin_unlock(&shmem_swaplist_lock); 847 } 848 unlock_page(page); 849 return 0; 850 } 851 852 shmem_swp_unmap(entry); 853 unlock: 854 spin_unlock(&info->lock); 855 swap_free(swap); 856 redirty: 857 set_page_dirty(page); 858 return WRITEPAGE_ACTIVATE; /* Return with the page locked */ 859 } 860 861 #ifdef CONFIG_NUMA 862 static struct page *shmem_swapin_async(struct shared_policy *p, 863 swp_entry_t entry, unsigned long idx) 864 { 865 struct page *page; 866 struct vm_area_struct pvma; 867 868 /* Create a pseudo vma that just contains the policy */ 869 memset(&pvma, 0, sizeof(struct vm_area_struct)); 870 pvma.vm_end = PAGE_SIZE; 871 pvma.vm_pgoff = idx; 872 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 873 page = read_swap_cache_async(entry, &pvma, 0); 874 mpol_free(pvma.vm_policy); 875 return page; 876 } 877 878 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 879 unsigned long idx) 880 { 881 struct shared_policy *p = &info->policy; 882 int i, num; 883 struct page *page; 884 unsigned long offset; 885 886 num = valid_swaphandles(entry, &offset); 887 for (i = 0; i < num; offset++, i++) { 888 page = shmem_swapin_async(p, 889 swp_entry(swp_type(entry), offset), idx); 890 if (!page) 891 break; 892 page_cache_release(page); 893 } 894 lru_add_drain(); /* Push any new pages onto the LRU now */ 895 return shmem_swapin_async(p, entry, idx); 896 } 897 898 static struct page * 899 shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, 900 unsigned long idx) 901 { 902 struct vm_area_struct pvma; 903 struct page *page; 904 905 memset(&pvma, 0, sizeof(struct vm_area_struct)); 906 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 907 pvma.vm_pgoff = idx; 908 pvma.vm_end = PAGE_SIZE; 909 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 910 mpol_free(pvma.vm_policy); 911 return page; 912 } 913 #else 914 static inline struct page * 915 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 916 { 917 swapin_readahead(entry, 0, NULL); 918 return read_swap_cache_async(entry, NULL, 0); 919 } 920 921 static inline struct page * 922 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) 923 { 924 return alloc_page(gfp | __GFP_ZERO); 925 } 926 #endif 927 928 /* 929 * shmem_getpage - either get the page from swap or allocate a new one 930 * 931 * If we allocate a new one we do not mark it dirty. That's up to the 932 * vm. If we swap it in we mark it dirty since we also free the swap 933 * entry since a page cannot live in both the swap and page cache 934 */ 935 static int shmem_getpage(struct inode *inode, unsigned long idx, 936 struct page **pagep, enum sgp_type sgp, int *type) 937 { 938 struct address_space *mapping = inode->i_mapping; 939 struct shmem_inode_info *info = SHMEM_I(inode); 940 struct shmem_sb_info *sbinfo; 941 struct page *filepage = *pagep; 942 struct page *swappage; 943 swp_entry_t *entry; 944 swp_entry_t swap; 945 int error; 946 947 if (idx >= SHMEM_MAX_INDEX) 948 return -EFBIG; 949 /* 950 * Normally, filepage is NULL on entry, and either found 951 * uptodate immediately, or allocated and zeroed, or read 952 * in under swappage, which is then assigned to filepage. 953 * But shmem_prepare_write passes in a locked filepage, 954 * which may be found not uptodate by other callers too, 955 * and may need to be copied from the swappage read in. 956 */ 957 repeat: 958 if (!filepage) 959 filepage = find_lock_page(mapping, idx); 960 if (filepage && PageUptodate(filepage)) 961 goto done; 962 error = 0; 963 if (sgp == SGP_QUICK) 964 goto failed; 965 966 spin_lock(&info->lock); 967 shmem_recalc_inode(inode); 968 entry = shmem_swp_alloc(info, idx, sgp); 969 if (IS_ERR(entry)) { 970 spin_unlock(&info->lock); 971 error = PTR_ERR(entry); 972 goto failed; 973 } 974 swap = *entry; 975 976 if (swap.val) { 977 /* Look it up and read it in.. */ 978 swappage = lookup_swap_cache(swap); 979 if (!swappage) { 980 shmem_swp_unmap(entry); 981 spin_unlock(&info->lock); 982 /* here we actually do the io */ 983 if (type && *type == VM_FAULT_MINOR) { 984 inc_page_state(pgmajfault); 985 *type = VM_FAULT_MAJOR; 986 } 987 swappage = shmem_swapin(info, swap, idx); 988 if (!swappage) { 989 spin_lock(&info->lock); 990 entry = shmem_swp_alloc(info, idx, sgp); 991 if (IS_ERR(entry)) 992 error = PTR_ERR(entry); 993 else { 994 if (entry->val == swap.val) 995 error = -ENOMEM; 996 shmem_swp_unmap(entry); 997 } 998 spin_unlock(&info->lock); 999 if (error) 1000 goto failed; 1001 goto repeat; 1002 } 1003 wait_on_page_locked(swappage); 1004 page_cache_release(swappage); 1005 goto repeat; 1006 } 1007 1008 /* We have to do this with page locked to prevent races */ 1009 if (TestSetPageLocked(swappage)) { 1010 shmem_swp_unmap(entry); 1011 spin_unlock(&info->lock); 1012 wait_on_page_locked(swappage); 1013 page_cache_release(swappage); 1014 goto repeat; 1015 } 1016 if (PageWriteback(swappage)) { 1017 shmem_swp_unmap(entry); 1018 spin_unlock(&info->lock); 1019 wait_on_page_writeback(swappage); 1020 unlock_page(swappage); 1021 page_cache_release(swappage); 1022 goto repeat; 1023 } 1024 if (!PageUptodate(swappage)) { 1025 shmem_swp_unmap(entry); 1026 spin_unlock(&info->lock); 1027 unlock_page(swappage); 1028 page_cache_release(swappage); 1029 error = -EIO; 1030 goto failed; 1031 } 1032 1033 if (filepage) { 1034 shmem_swp_set(info, entry, 0); 1035 shmem_swp_unmap(entry); 1036 delete_from_swap_cache(swappage); 1037 spin_unlock(&info->lock); 1038 copy_highpage(filepage, swappage); 1039 unlock_page(swappage); 1040 page_cache_release(swappage); 1041 flush_dcache_page(filepage); 1042 SetPageUptodate(filepage); 1043 set_page_dirty(filepage); 1044 swap_free(swap); 1045 } else if (!(error = move_from_swap_cache( 1046 swappage, idx, mapping))) { 1047 info->flags |= SHMEM_PAGEIN; 1048 shmem_swp_set(info, entry, 0); 1049 shmem_swp_unmap(entry); 1050 spin_unlock(&info->lock); 1051 filepage = swappage; 1052 swap_free(swap); 1053 } else { 1054 shmem_swp_unmap(entry); 1055 spin_unlock(&info->lock); 1056 unlock_page(swappage); 1057 page_cache_release(swappage); 1058 if (error == -ENOMEM) { 1059 /* let kswapd refresh zone for GFP_ATOMICs */ 1060 blk_congestion_wait(WRITE, HZ/50); 1061 } 1062 goto repeat; 1063 } 1064 } else if (sgp == SGP_READ && !filepage) { 1065 shmem_swp_unmap(entry); 1066 filepage = find_get_page(mapping, idx); 1067 if (filepage && 1068 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1069 spin_unlock(&info->lock); 1070 wait_on_page_locked(filepage); 1071 page_cache_release(filepage); 1072 filepage = NULL; 1073 goto repeat; 1074 } 1075 spin_unlock(&info->lock); 1076 } else { 1077 shmem_swp_unmap(entry); 1078 sbinfo = SHMEM_SB(inode->i_sb); 1079 if (sbinfo->max_blocks) { 1080 spin_lock(&sbinfo->stat_lock); 1081 if (sbinfo->free_blocks == 0 || 1082 shmem_acct_block(info->flags)) { 1083 spin_unlock(&sbinfo->stat_lock); 1084 spin_unlock(&info->lock); 1085 error = -ENOSPC; 1086 goto failed; 1087 } 1088 sbinfo->free_blocks--; 1089 inode->i_blocks += BLOCKS_PER_PAGE; 1090 spin_unlock(&sbinfo->stat_lock); 1091 } else if (shmem_acct_block(info->flags)) { 1092 spin_unlock(&info->lock); 1093 error = -ENOSPC; 1094 goto failed; 1095 } 1096 1097 if (!filepage) { 1098 spin_unlock(&info->lock); 1099 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1100 info, 1101 idx); 1102 if (!filepage) { 1103 shmem_unacct_blocks(info->flags, 1); 1104 shmem_free_blocks(inode, 1); 1105 error = -ENOMEM; 1106 goto failed; 1107 } 1108 1109 spin_lock(&info->lock); 1110 entry = shmem_swp_alloc(info, idx, sgp); 1111 if (IS_ERR(entry)) 1112 error = PTR_ERR(entry); 1113 else { 1114 swap = *entry; 1115 shmem_swp_unmap(entry); 1116 } 1117 if (error || swap.val || 0 != add_to_page_cache_lru( 1118 filepage, mapping, idx, GFP_ATOMIC)) { 1119 spin_unlock(&info->lock); 1120 page_cache_release(filepage); 1121 shmem_unacct_blocks(info->flags, 1); 1122 shmem_free_blocks(inode, 1); 1123 filepage = NULL; 1124 if (error) 1125 goto failed; 1126 goto repeat; 1127 } 1128 info->flags |= SHMEM_PAGEIN; 1129 } 1130 1131 info->alloced++; 1132 spin_unlock(&info->lock); 1133 flush_dcache_page(filepage); 1134 SetPageUptodate(filepage); 1135 } 1136 done: 1137 if (*pagep != filepage) { 1138 unlock_page(filepage); 1139 *pagep = filepage; 1140 } 1141 return 0; 1142 1143 failed: 1144 if (*pagep != filepage) { 1145 unlock_page(filepage); 1146 page_cache_release(filepage); 1147 } 1148 return error; 1149 } 1150 1151 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type) 1152 { 1153 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1154 struct page *page = NULL; 1155 unsigned long idx; 1156 int error; 1157 1158 idx = (address - vma->vm_start) >> PAGE_SHIFT; 1159 idx += vma->vm_pgoff; 1160 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; 1161 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1162 return NOPAGE_SIGBUS; 1163 1164 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); 1165 if (error) 1166 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; 1167 1168 mark_page_accessed(page); 1169 return page; 1170 } 1171 1172 static int shmem_populate(struct vm_area_struct *vma, 1173 unsigned long addr, unsigned long len, 1174 pgprot_t prot, unsigned long pgoff, int nonblock) 1175 { 1176 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1177 struct mm_struct *mm = vma->vm_mm; 1178 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; 1179 unsigned long size; 1180 1181 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; 1182 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) 1183 return -EINVAL; 1184 1185 while ((long) len > 0) { 1186 struct page *page = NULL; 1187 int err; 1188 /* 1189 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE 1190 */ 1191 err = shmem_getpage(inode, pgoff, &page, sgp, NULL); 1192 if (err) 1193 return err; 1194 /* Page may still be null, but only if nonblock was set. */ 1195 if (page) { 1196 mark_page_accessed(page); 1197 err = install_page(mm, vma, addr, page, prot); 1198 if (err) { 1199 page_cache_release(page); 1200 return err; 1201 } 1202 } else if (vma->vm_flags & VM_NONLINEAR) { 1203 /* No page was found just because we can't read it in 1204 * now (being here implies nonblock != 0), but the page 1205 * may exist, so set the PTE to fault it in later. */ 1206 err = install_file_pte(mm, vma, addr, pgoff, prot); 1207 if (err) 1208 return err; 1209 } 1210 1211 len -= PAGE_SIZE; 1212 addr += PAGE_SIZE; 1213 pgoff++; 1214 } 1215 return 0; 1216 } 1217 1218 #ifdef CONFIG_NUMA 1219 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1220 { 1221 struct inode *i = vma->vm_file->f_dentry->d_inode; 1222 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1223 } 1224 1225 struct mempolicy * 1226 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) 1227 { 1228 struct inode *i = vma->vm_file->f_dentry->d_inode; 1229 unsigned long idx; 1230 1231 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1232 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1233 } 1234 #endif 1235 1236 int shmem_lock(struct file *file, int lock, struct user_struct *user) 1237 { 1238 struct inode *inode = file->f_dentry->d_inode; 1239 struct shmem_inode_info *info = SHMEM_I(inode); 1240 int retval = -ENOMEM; 1241 1242 spin_lock(&info->lock); 1243 if (lock && !(info->flags & VM_LOCKED)) { 1244 if (!user_shm_lock(inode->i_size, user)) 1245 goto out_nomem; 1246 info->flags |= VM_LOCKED; 1247 } 1248 if (!lock && (info->flags & VM_LOCKED) && user) { 1249 user_shm_unlock(inode->i_size, user); 1250 info->flags &= ~VM_LOCKED; 1251 } 1252 retval = 0; 1253 out_nomem: 1254 spin_unlock(&info->lock); 1255 return retval; 1256 } 1257 1258 static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1259 { 1260 file_accessed(file); 1261 vma->vm_ops = &shmem_vm_ops; 1262 return 0; 1263 } 1264 1265 static struct inode * 1266 shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1267 { 1268 struct inode *inode; 1269 struct shmem_inode_info *info; 1270 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1271 1272 if (sbinfo->max_inodes) { 1273 spin_lock(&sbinfo->stat_lock); 1274 if (!sbinfo->free_inodes) { 1275 spin_unlock(&sbinfo->stat_lock); 1276 return NULL; 1277 } 1278 sbinfo->free_inodes--; 1279 spin_unlock(&sbinfo->stat_lock); 1280 } 1281 1282 inode = new_inode(sb); 1283 if (inode) { 1284 inode->i_mode = mode; 1285 inode->i_uid = current->fsuid; 1286 inode->i_gid = current->fsgid; 1287 inode->i_blksize = PAGE_CACHE_SIZE; 1288 inode->i_blocks = 0; 1289 inode->i_mapping->a_ops = &shmem_aops; 1290 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1291 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1292 info = SHMEM_I(inode); 1293 memset(info, 0, (char *)inode - (char *)info); 1294 spin_lock_init(&info->lock); 1295 INIT_LIST_HEAD(&info->swaplist); 1296 1297 switch (mode & S_IFMT) { 1298 default: 1299 init_special_inode(inode, mode, dev); 1300 break; 1301 case S_IFREG: 1302 inode->i_op = &shmem_inode_operations; 1303 inode->i_fop = &shmem_file_operations; 1304 mpol_shared_policy_init(&info->policy); 1305 break; 1306 case S_IFDIR: 1307 inode->i_nlink++; 1308 /* Some things misbehave if size == 0 on a directory */ 1309 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1310 inode->i_op = &shmem_dir_inode_operations; 1311 inode->i_fop = &simple_dir_operations; 1312 break; 1313 case S_IFLNK: 1314 /* 1315 * Must not load anything in the rbtree, 1316 * mpol_free_shared_policy will not be called. 1317 */ 1318 mpol_shared_policy_init(&info->policy); 1319 break; 1320 } 1321 } else if (sbinfo->max_inodes) { 1322 spin_lock(&sbinfo->stat_lock); 1323 sbinfo->free_inodes++; 1324 spin_unlock(&sbinfo->stat_lock); 1325 } 1326 return inode; 1327 } 1328 1329 #ifdef CONFIG_TMPFS 1330 static struct inode_operations shmem_symlink_inode_operations; 1331 static struct inode_operations shmem_symlink_inline_operations; 1332 1333 /* 1334 * Normally tmpfs makes no use of shmem_prepare_write, but it 1335 * lets a tmpfs file be used read-write below the loop driver. 1336 */ 1337 static int 1338 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) 1339 { 1340 struct inode *inode = page->mapping->host; 1341 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); 1342 } 1343 1344 static ssize_t 1345 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1346 { 1347 struct inode *inode = file->f_dentry->d_inode; 1348 loff_t pos; 1349 unsigned long written; 1350 ssize_t err; 1351 1352 if ((ssize_t) count < 0) 1353 return -EINVAL; 1354 1355 if (!access_ok(VERIFY_READ, buf, count)) 1356 return -EFAULT; 1357 1358 down(&inode->i_sem); 1359 1360 pos = *ppos; 1361 written = 0; 1362 1363 err = generic_write_checks(file, &pos, &count, 0); 1364 if (err || !count) 1365 goto out; 1366 1367 err = remove_suid(file->f_dentry); 1368 if (err) 1369 goto out; 1370 1371 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1372 1373 do { 1374 struct page *page = NULL; 1375 unsigned long bytes, index, offset; 1376 char *kaddr; 1377 int left; 1378 1379 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1380 index = pos >> PAGE_CACHE_SHIFT; 1381 bytes = PAGE_CACHE_SIZE - offset; 1382 if (bytes > count) 1383 bytes = count; 1384 1385 /* 1386 * We don't hold page lock across copy from user - 1387 * what would it guard against? - so no deadlock here. 1388 * But it still may be a good idea to prefault below. 1389 */ 1390 1391 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1392 if (err) 1393 break; 1394 1395 left = bytes; 1396 if (PageHighMem(page)) { 1397 volatile unsigned char dummy; 1398 __get_user(dummy, buf); 1399 __get_user(dummy, buf + bytes - 1); 1400 1401 kaddr = kmap_atomic(page, KM_USER0); 1402 left = __copy_from_user_inatomic(kaddr + offset, 1403 buf, bytes); 1404 kunmap_atomic(kaddr, KM_USER0); 1405 } 1406 if (left) { 1407 kaddr = kmap(page); 1408 left = __copy_from_user(kaddr + offset, buf, bytes); 1409 kunmap(page); 1410 } 1411 1412 written += bytes; 1413 count -= bytes; 1414 pos += bytes; 1415 buf += bytes; 1416 if (pos > inode->i_size) 1417 i_size_write(inode, pos); 1418 1419 flush_dcache_page(page); 1420 set_page_dirty(page); 1421 mark_page_accessed(page); 1422 page_cache_release(page); 1423 1424 if (left) { 1425 pos -= left; 1426 written -= left; 1427 err = -EFAULT; 1428 break; 1429 } 1430 1431 /* 1432 * Our dirty pages are not counted in nr_dirty, 1433 * and we do not attempt to balance dirty pages. 1434 */ 1435 1436 cond_resched(); 1437 } while (count); 1438 1439 *ppos = pos; 1440 if (written) 1441 err = written; 1442 out: 1443 up(&inode->i_sem); 1444 return err; 1445 } 1446 1447 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1448 { 1449 struct inode *inode = filp->f_dentry->d_inode; 1450 struct address_space *mapping = inode->i_mapping; 1451 unsigned long index, offset; 1452 1453 index = *ppos >> PAGE_CACHE_SHIFT; 1454 offset = *ppos & ~PAGE_CACHE_MASK; 1455 1456 for (;;) { 1457 struct page *page = NULL; 1458 unsigned long end_index, nr, ret; 1459 loff_t i_size = i_size_read(inode); 1460 1461 end_index = i_size >> PAGE_CACHE_SHIFT; 1462 if (index > end_index) 1463 break; 1464 if (index == end_index) { 1465 nr = i_size & ~PAGE_CACHE_MASK; 1466 if (nr <= offset) 1467 break; 1468 } 1469 1470 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1471 if (desc->error) { 1472 if (desc->error == -EINVAL) 1473 desc->error = 0; 1474 break; 1475 } 1476 1477 /* 1478 * We must evaluate after, since reads (unlike writes) 1479 * are called without i_sem protection against truncate 1480 */ 1481 nr = PAGE_CACHE_SIZE; 1482 i_size = i_size_read(inode); 1483 end_index = i_size >> PAGE_CACHE_SHIFT; 1484 if (index == end_index) { 1485 nr = i_size & ~PAGE_CACHE_MASK; 1486 if (nr <= offset) { 1487 if (page) 1488 page_cache_release(page); 1489 break; 1490 } 1491 } 1492 nr -= offset; 1493 1494 if (page) { 1495 /* 1496 * If users can be writing to this page using arbitrary 1497 * virtual addresses, take care about potential aliasing 1498 * before reading the page on the kernel side. 1499 */ 1500 if (mapping_writably_mapped(mapping)) 1501 flush_dcache_page(page); 1502 /* 1503 * Mark the page accessed if we read the beginning. 1504 */ 1505 if (!offset) 1506 mark_page_accessed(page); 1507 } else { 1508 page = ZERO_PAGE(0); 1509 page_cache_get(page); 1510 } 1511 1512 /* 1513 * Ok, we have the page, and it's up-to-date, so 1514 * now we can copy it to user space... 1515 * 1516 * The actor routine returns how many bytes were actually used.. 1517 * NOTE! This may not be the same as how much of a user buffer 1518 * we filled up (we may be padding etc), so we can only update 1519 * "pos" here (the actor routine has to update the user buffer 1520 * pointers and the remaining count). 1521 */ 1522 ret = actor(desc, page, offset, nr); 1523 offset += ret; 1524 index += offset >> PAGE_CACHE_SHIFT; 1525 offset &= ~PAGE_CACHE_MASK; 1526 1527 page_cache_release(page); 1528 if (ret != nr || !desc->count) 1529 break; 1530 1531 cond_resched(); 1532 } 1533 1534 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1535 file_accessed(filp); 1536 } 1537 1538 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1539 { 1540 read_descriptor_t desc; 1541 1542 if ((ssize_t) count < 0) 1543 return -EINVAL; 1544 if (!access_ok(VERIFY_WRITE, buf, count)) 1545 return -EFAULT; 1546 if (!count) 1547 return 0; 1548 1549 desc.written = 0; 1550 desc.count = count; 1551 desc.arg.buf = buf; 1552 desc.error = 0; 1553 1554 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1555 if (desc.written) 1556 return desc.written; 1557 return desc.error; 1558 } 1559 1560 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, 1561 size_t count, read_actor_t actor, void *target) 1562 { 1563 read_descriptor_t desc; 1564 1565 if (!count) 1566 return 0; 1567 1568 desc.written = 0; 1569 desc.count = count; 1570 desc.arg.data = target; 1571 desc.error = 0; 1572 1573 do_shmem_file_read(in_file, ppos, &desc, actor); 1574 if (desc.written) 1575 return desc.written; 1576 return desc.error; 1577 } 1578 1579 static int shmem_statfs(struct super_block *sb, struct kstatfs *buf) 1580 { 1581 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1582 1583 buf->f_type = TMPFS_MAGIC; 1584 buf->f_bsize = PAGE_CACHE_SIZE; 1585 buf->f_namelen = NAME_MAX; 1586 spin_lock(&sbinfo->stat_lock); 1587 if (sbinfo->max_blocks) { 1588 buf->f_blocks = sbinfo->max_blocks; 1589 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1590 } 1591 if (sbinfo->max_inodes) { 1592 buf->f_files = sbinfo->max_inodes; 1593 buf->f_ffree = sbinfo->free_inodes; 1594 } 1595 /* else leave those fields 0 like simple_statfs */ 1596 spin_unlock(&sbinfo->stat_lock); 1597 return 0; 1598 } 1599 1600 /* 1601 * File creation. Allocate an inode, and we're done.. 1602 */ 1603 static int 1604 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1605 { 1606 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1607 int error = -ENOSPC; 1608 1609 if (inode) { 1610 error = security_inode_init_security(inode, dir, NULL, NULL, 1611 NULL); 1612 if (error) { 1613 if (error != -EOPNOTSUPP) { 1614 iput(inode); 1615 return error; 1616 } 1617 error = 0; 1618 } 1619 if (dir->i_mode & S_ISGID) { 1620 inode->i_gid = dir->i_gid; 1621 if (S_ISDIR(mode)) 1622 inode->i_mode |= S_ISGID; 1623 } 1624 dir->i_size += BOGO_DIRENT_SIZE; 1625 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1626 d_instantiate(dentry, inode); 1627 dget(dentry); /* Extra count - pin the dentry in core */ 1628 } 1629 return error; 1630 } 1631 1632 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1633 { 1634 int error; 1635 1636 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1637 return error; 1638 dir->i_nlink++; 1639 return 0; 1640 } 1641 1642 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1643 struct nameidata *nd) 1644 { 1645 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1646 } 1647 1648 /* 1649 * Link a file.. 1650 */ 1651 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1652 { 1653 struct inode *inode = old_dentry->d_inode; 1654 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1655 1656 /* 1657 * No ordinary (disk based) filesystem counts links as inodes; 1658 * but each new link needs a new dentry, pinning lowmem, and 1659 * tmpfs dentries cannot be pruned until they are unlinked. 1660 */ 1661 if (sbinfo->max_inodes) { 1662 spin_lock(&sbinfo->stat_lock); 1663 if (!sbinfo->free_inodes) { 1664 spin_unlock(&sbinfo->stat_lock); 1665 return -ENOSPC; 1666 } 1667 sbinfo->free_inodes--; 1668 spin_unlock(&sbinfo->stat_lock); 1669 } 1670 1671 dir->i_size += BOGO_DIRENT_SIZE; 1672 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1673 inode->i_nlink++; 1674 atomic_inc(&inode->i_count); /* New dentry reference */ 1675 dget(dentry); /* Extra pinning count for the created dentry */ 1676 d_instantiate(dentry, inode); 1677 return 0; 1678 } 1679 1680 static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1681 { 1682 struct inode *inode = dentry->d_inode; 1683 1684 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1685 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1686 if (sbinfo->max_inodes) { 1687 spin_lock(&sbinfo->stat_lock); 1688 sbinfo->free_inodes++; 1689 spin_unlock(&sbinfo->stat_lock); 1690 } 1691 } 1692 1693 dir->i_size -= BOGO_DIRENT_SIZE; 1694 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1695 inode->i_nlink--; 1696 dput(dentry); /* Undo the count from "create" - this does all the work */ 1697 return 0; 1698 } 1699 1700 static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1701 { 1702 if (!simple_empty(dentry)) 1703 return -ENOTEMPTY; 1704 1705 dir->i_nlink--; 1706 return shmem_unlink(dir, dentry); 1707 } 1708 1709 /* 1710 * The VFS layer already does all the dentry stuff for rename, 1711 * we just have to decrement the usage count for the target if 1712 * it exists so that the VFS layer correctly free's it when it 1713 * gets overwritten. 1714 */ 1715 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1716 { 1717 struct inode *inode = old_dentry->d_inode; 1718 int they_are_dirs = S_ISDIR(inode->i_mode); 1719 1720 if (!simple_empty(new_dentry)) 1721 return -ENOTEMPTY; 1722 1723 if (new_dentry->d_inode) { 1724 (void) shmem_unlink(new_dir, new_dentry); 1725 if (they_are_dirs) 1726 old_dir->i_nlink--; 1727 } else if (they_are_dirs) { 1728 old_dir->i_nlink--; 1729 new_dir->i_nlink++; 1730 } 1731 1732 old_dir->i_size -= BOGO_DIRENT_SIZE; 1733 new_dir->i_size += BOGO_DIRENT_SIZE; 1734 old_dir->i_ctime = old_dir->i_mtime = 1735 new_dir->i_ctime = new_dir->i_mtime = 1736 inode->i_ctime = CURRENT_TIME; 1737 return 0; 1738 } 1739 1740 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1741 { 1742 int error; 1743 int len; 1744 struct inode *inode; 1745 struct page *page = NULL; 1746 char *kaddr; 1747 struct shmem_inode_info *info; 1748 1749 len = strlen(symname) + 1; 1750 if (len > PAGE_CACHE_SIZE) 1751 return -ENAMETOOLONG; 1752 1753 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1754 if (!inode) 1755 return -ENOSPC; 1756 1757 error = security_inode_init_security(inode, dir, NULL, NULL, 1758 NULL); 1759 if (error) { 1760 if (error != -EOPNOTSUPP) { 1761 iput(inode); 1762 return error; 1763 } 1764 error = 0; 1765 } 1766 1767 info = SHMEM_I(inode); 1768 inode->i_size = len-1; 1769 if (len <= (char *)inode - (char *)info) { 1770 /* do it inline */ 1771 memcpy(info, symname, len); 1772 inode->i_op = &shmem_symlink_inline_operations; 1773 } else { 1774 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1775 if (error) { 1776 iput(inode); 1777 return error; 1778 } 1779 inode->i_op = &shmem_symlink_inode_operations; 1780 kaddr = kmap_atomic(page, KM_USER0); 1781 memcpy(kaddr, symname, len); 1782 kunmap_atomic(kaddr, KM_USER0); 1783 set_page_dirty(page); 1784 page_cache_release(page); 1785 } 1786 if (dir->i_mode & S_ISGID) 1787 inode->i_gid = dir->i_gid; 1788 dir->i_size += BOGO_DIRENT_SIZE; 1789 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1790 d_instantiate(dentry, inode); 1791 dget(dentry); 1792 return 0; 1793 } 1794 1795 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1796 { 1797 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1798 return NULL; 1799 } 1800 1801 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1802 { 1803 struct page *page = NULL; 1804 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1805 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1806 return page; 1807 } 1808 1809 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1810 { 1811 if (!IS_ERR(nd_get_link(nd))) { 1812 struct page *page = cookie; 1813 kunmap(page); 1814 mark_page_accessed(page); 1815 page_cache_release(page); 1816 } 1817 } 1818 1819 static struct inode_operations shmem_symlink_inline_operations = { 1820 .readlink = generic_readlink, 1821 .follow_link = shmem_follow_link_inline, 1822 }; 1823 1824 static struct inode_operations shmem_symlink_inode_operations = { 1825 .truncate = shmem_truncate, 1826 .readlink = generic_readlink, 1827 .follow_link = shmem_follow_link, 1828 .put_link = shmem_put_link, 1829 }; 1830 1831 static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes) 1832 { 1833 char *this_char, *value, *rest; 1834 1835 while ((this_char = strsep(&options, ",")) != NULL) { 1836 if (!*this_char) 1837 continue; 1838 if ((value = strchr(this_char,'=')) != NULL) { 1839 *value++ = 0; 1840 } else { 1841 printk(KERN_ERR 1842 "tmpfs: No value for mount option '%s'\n", 1843 this_char); 1844 return 1; 1845 } 1846 1847 if (!strcmp(this_char,"size")) { 1848 unsigned long long size; 1849 size = memparse(value,&rest); 1850 if (*rest == '%') { 1851 size <<= PAGE_SHIFT; 1852 size *= totalram_pages; 1853 do_div(size, 100); 1854 rest++; 1855 } 1856 if (*rest) 1857 goto bad_val; 1858 *blocks = size >> PAGE_CACHE_SHIFT; 1859 } else if (!strcmp(this_char,"nr_blocks")) { 1860 *blocks = memparse(value,&rest); 1861 if (*rest) 1862 goto bad_val; 1863 } else if (!strcmp(this_char,"nr_inodes")) { 1864 *inodes = memparse(value,&rest); 1865 if (*rest) 1866 goto bad_val; 1867 } else if (!strcmp(this_char,"mode")) { 1868 if (!mode) 1869 continue; 1870 *mode = simple_strtoul(value,&rest,8); 1871 if (*rest) 1872 goto bad_val; 1873 } else if (!strcmp(this_char,"uid")) { 1874 if (!uid) 1875 continue; 1876 *uid = simple_strtoul(value,&rest,0); 1877 if (*rest) 1878 goto bad_val; 1879 } else if (!strcmp(this_char,"gid")) { 1880 if (!gid) 1881 continue; 1882 *gid = simple_strtoul(value,&rest,0); 1883 if (*rest) 1884 goto bad_val; 1885 } else { 1886 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 1887 this_char); 1888 return 1; 1889 } 1890 } 1891 return 0; 1892 1893 bad_val: 1894 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 1895 value, this_char); 1896 return 1; 1897 1898 } 1899 1900 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 1901 { 1902 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1903 unsigned long max_blocks = sbinfo->max_blocks; 1904 unsigned long max_inodes = sbinfo->max_inodes; 1905 unsigned long blocks; 1906 unsigned long inodes; 1907 int error = -EINVAL; 1908 1909 if (shmem_parse_options(data, NULL, NULL, NULL, 1910 &max_blocks, &max_inodes)) 1911 return error; 1912 1913 spin_lock(&sbinfo->stat_lock); 1914 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 1915 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 1916 if (max_blocks < blocks) 1917 goto out; 1918 if (max_inodes < inodes) 1919 goto out; 1920 /* 1921 * Those tests also disallow limited->unlimited while any are in 1922 * use, so i_blocks will always be zero when max_blocks is zero; 1923 * but we must separately disallow unlimited->limited, because 1924 * in that case we have no record of how much is already in use. 1925 */ 1926 if (max_blocks && !sbinfo->max_blocks) 1927 goto out; 1928 if (max_inodes && !sbinfo->max_inodes) 1929 goto out; 1930 1931 error = 0; 1932 sbinfo->max_blocks = max_blocks; 1933 sbinfo->free_blocks = max_blocks - blocks; 1934 sbinfo->max_inodes = max_inodes; 1935 sbinfo->free_inodes = max_inodes - inodes; 1936 out: 1937 spin_unlock(&sbinfo->stat_lock); 1938 return error; 1939 } 1940 #endif 1941 1942 static void shmem_put_super(struct super_block *sb) 1943 { 1944 kfree(sb->s_fs_info); 1945 sb->s_fs_info = NULL; 1946 } 1947 1948 static int shmem_fill_super(struct super_block *sb, 1949 void *data, int silent) 1950 { 1951 struct inode *inode; 1952 struct dentry *root; 1953 int mode = S_IRWXUGO | S_ISVTX; 1954 uid_t uid = current->fsuid; 1955 gid_t gid = current->fsgid; 1956 int err = -ENOMEM; 1957 struct shmem_sb_info *sbinfo; 1958 unsigned long blocks = 0; 1959 unsigned long inodes = 0; 1960 1961 #ifdef CONFIG_TMPFS 1962 /* 1963 * Per default we only allow half of the physical ram per 1964 * tmpfs instance, limiting inodes to one per page of lowmem; 1965 * but the internal instance is left unlimited. 1966 */ 1967 if (!(sb->s_flags & MS_NOUSER)) { 1968 blocks = totalram_pages / 2; 1969 inodes = totalram_pages - totalhigh_pages; 1970 if (inodes > blocks) 1971 inodes = blocks; 1972 if (shmem_parse_options(data, &mode, &uid, &gid, 1973 &blocks, &inodes)) 1974 return -EINVAL; 1975 } 1976 #else 1977 sb->s_flags |= MS_NOUSER; 1978 #endif 1979 1980 /* Round up to L1_CACHE_BYTES to resist false sharing */ 1981 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 1982 L1_CACHE_BYTES), GFP_KERNEL); 1983 if (!sbinfo) 1984 return -ENOMEM; 1985 1986 spin_lock_init(&sbinfo->stat_lock); 1987 sbinfo->max_blocks = blocks; 1988 sbinfo->free_blocks = blocks; 1989 sbinfo->max_inodes = inodes; 1990 sbinfo->free_inodes = inodes; 1991 1992 sb->s_fs_info = sbinfo; 1993 sb->s_maxbytes = SHMEM_MAX_BYTES; 1994 sb->s_blocksize = PAGE_CACHE_SIZE; 1995 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 1996 sb->s_magic = TMPFS_MAGIC; 1997 sb->s_op = &shmem_ops; 1998 1999 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2000 if (!inode) 2001 goto failed; 2002 inode->i_uid = uid; 2003 inode->i_gid = gid; 2004 root = d_alloc_root(inode); 2005 if (!root) 2006 goto failed_iput; 2007 sb->s_root = root; 2008 return 0; 2009 2010 failed_iput: 2011 iput(inode); 2012 failed: 2013 shmem_put_super(sb); 2014 return err; 2015 } 2016 2017 static kmem_cache_t *shmem_inode_cachep; 2018 2019 static struct inode *shmem_alloc_inode(struct super_block *sb) 2020 { 2021 struct shmem_inode_info *p; 2022 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL); 2023 if (!p) 2024 return NULL; 2025 return &p->vfs_inode; 2026 } 2027 2028 static void shmem_destroy_inode(struct inode *inode) 2029 { 2030 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2031 /* only struct inode is valid if it's an inline symlink */ 2032 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2033 } 2034 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2035 } 2036 2037 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags) 2038 { 2039 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2040 2041 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 2042 SLAB_CTOR_CONSTRUCTOR) { 2043 inode_init_once(&p->vfs_inode); 2044 } 2045 } 2046 2047 static int init_inodecache(void) 2048 { 2049 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2050 sizeof(struct shmem_inode_info), 2051 0, 0, init_once, NULL); 2052 if (shmem_inode_cachep == NULL) 2053 return -ENOMEM; 2054 return 0; 2055 } 2056 2057 static void destroy_inodecache(void) 2058 { 2059 if (kmem_cache_destroy(shmem_inode_cachep)) 2060 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n"); 2061 } 2062 2063 static struct address_space_operations shmem_aops = { 2064 .writepage = shmem_writepage, 2065 .set_page_dirty = __set_page_dirty_nobuffers, 2066 #ifdef CONFIG_TMPFS 2067 .prepare_write = shmem_prepare_write, 2068 .commit_write = simple_commit_write, 2069 #endif 2070 }; 2071 2072 static struct file_operations shmem_file_operations = { 2073 .mmap = shmem_mmap, 2074 #ifdef CONFIG_TMPFS 2075 .llseek = generic_file_llseek, 2076 .read = shmem_file_read, 2077 .write = shmem_file_write, 2078 .fsync = simple_sync_file, 2079 .sendfile = shmem_file_sendfile, 2080 #endif 2081 }; 2082 2083 static struct inode_operations shmem_inode_operations = { 2084 .truncate = shmem_truncate, 2085 .setattr = shmem_notify_change, 2086 }; 2087 2088 static struct inode_operations shmem_dir_inode_operations = { 2089 #ifdef CONFIG_TMPFS 2090 .create = shmem_create, 2091 .lookup = simple_lookup, 2092 .link = shmem_link, 2093 .unlink = shmem_unlink, 2094 .symlink = shmem_symlink, 2095 .mkdir = shmem_mkdir, 2096 .rmdir = shmem_rmdir, 2097 .mknod = shmem_mknod, 2098 .rename = shmem_rename, 2099 #endif 2100 }; 2101 2102 static struct super_operations shmem_ops = { 2103 .alloc_inode = shmem_alloc_inode, 2104 .destroy_inode = shmem_destroy_inode, 2105 #ifdef CONFIG_TMPFS 2106 .statfs = shmem_statfs, 2107 .remount_fs = shmem_remount_fs, 2108 #endif 2109 .delete_inode = shmem_delete_inode, 2110 .drop_inode = generic_delete_inode, 2111 .put_super = shmem_put_super, 2112 }; 2113 2114 static struct vm_operations_struct shmem_vm_ops = { 2115 .nopage = shmem_nopage, 2116 .populate = shmem_populate, 2117 #ifdef CONFIG_NUMA 2118 .set_policy = shmem_set_policy, 2119 .get_policy = shmem_get_policy, 2120 #endif 2121 }; 2122 2123 2124 static struct super_block *shmem_get_sb(struct file_system_type *fs_type, 2125 int flags, const char *dev_name, void *data) 2126 { 2127 return get_sb_nodev(fs_type, flags, data, shmem_fill_super); 2128 } 2129 2130 static struct file_system_type tmpfs_fs_type = { 2131 .owner = THIS_MODULE, 2132 .name = "tmpfs", 2133 .get_sb = shmem_get_sb, 2134 .kill_sb = kill_litter_super, 2135 }; 2136 static struct vfsmount *shm_mnt; 2137 2138 static int __init init_tmpfs(void) 2139 { 2140 int error; 2141 2142 error = init_inodecache(); 2143 if (error) 2144 goto out3; 2145 2146 error = register_filesystem(&tmpfs_fs_type); 2147 if (error) { 2148 printk(KERN_ERR "Could not register tmpfs\n"); 2149 goto out2; 2150 } 2151 #ifdef CONFIG_TMPFS 2152 devfs_mk_dir("shm"); 2153 #endif 2154 shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER, 2155 tmpfs_fs_type.name, NULL); 2156 if (IS_ERR(shm_mnt)) { 2157 error = PTR_ERR(shm_mnt); 2158 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2159 goto out1; 2160 } 2161 return 0; 2162 2163 out1: 2164 unregister_filesystem(&tmpfs_fs_type); 2165 out2: 2166 destroy_inodecache(); 2167 out3: 2168 shm_mnt = ERR_PTR(error); 2169 return error; 2170 } 2171 module_init(init_tmpfs) 2172 2173 /* 2174 * shmem_file_setup - get an unlinked file living in tmpfs 2175 * 2176 * @name: name for dentry (to be seen in /proc/<pid>/maps 2177 * @size: size to be set for the file 2178 * 2179 */ 2180 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2181 { 2182 int error; 2183 struct file *file; 2184 struct inode *inode; 2185 struct dentry *dentry, *root; 2186 struct qstr this; 2187 2188 if (IS_ERR(shm_mnt)) 2189 return (void *)shm_mnt; 2190 2191 if (size < 0 || size > SHMEM_MAX_BYTES) 2192 return ERR_PTR(-EINVAL); 2193 2194 if (shmem_acct_size(flags, size)) 2195 return ERR_PTR(-ENOMEM); 2196 2197 error = -ENOMEM; 2198 this.name = name; 2199 this.len = strlen(name); 2200 this.hash = 0; /* will go */ 2201 root = shm_mnt->mnt_root; 2202 dentry = d_alloc(root, &this); 2203 if (!dentry) 2204 goto put_memory; 2205 2206 error = -ENFILE; 2207 file = get_empty_filp(); 2208 if (!file) 2209 goto put_dentry; 2210 2211 error = -ENOSPC; 2212 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2213 if (!inode) 2214 goto close_file; 2215 2216 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2217 d_instantiate(dentry, inode); 2218 inode->i_size = size; 2219 inode->i_nlink = 0; /* It is unlinked */ 2220 file->f_vfsmnt = mntget(shm_mnt); 2221 file->f_dentry = dentry; 2222 file->f_mapping = inode->i_mapping; 2223 file->f_op = &shmem_file_operations; 2224 file->f_mode = FMODE_WRITE | FMODE_READ; 2225 return file; 2226 2227 close_file: 2228 put_filp(file); 2229 put_dentry: 2230 dput(dentry); 2231 put_memory: 2232 shmem_unacct_size(flags, size); 2233 return ERR_PTR(error); 2234 } 2235 2236 /* 2237 * shmem_zero_setup - setup a shared anonymous mapping 2238 * 2239 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2240 */ 2241 int shmem_zero_setup(struct vm_area_struct *vma) 2242 { 2243 struct file *file; 2244 loff_t size = vma->vm_end - vma->vm_start; 2245 2246 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2247 if (IS_ERR(file)) 2248 return PTR_ERR(file); 2249 2250 if (vma->vm_file) 2251 fput(vma->vm_file); 2252 vma->vm_file = file; 2253 vma->vm_ops = &shmem_vm_ops; 2254 return 0; 2255 } 2256